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The aim of the SUSY conference is to review and discuss recent research related to supersymmetric theories and all other approaches to physics beyond the Standard Model in all aspects, including formal theory, phenomenology, experiment, astrophysics, cosmology, etc.
The Institute of Theoretical Physics (IFT, Madrid) is responsible for organising the 31st International Conference on Supersymmetry and Unification of Fundamental Interactions (SUSY 2024).
Registration will open on 15/02 and close on 31/05. Abstract submission is extended until the 13 of May.
WARNING: Please be wary of fraudulent/phishing emails offering to book accommodation for the conference. We have not organized central reservations/bookings nor partnered with any companies for this. Any email of this kind you receive is spam. And of course in case of any doubts, please contact us directly!
Please contact susy24madrid@gmail.com in case of questions.
The individual fermion generations of the Standard Model fit neatly into a representation of a simple Grand Unified Theory gauge algebra. If Grand Unification is not realised in nature, this would appear to be a coincidence. We attempt to quantify how frequent this coincidence is among theories with group structure and fermion content similar to the Standard Model. While not constituting evidence, this bottom-up theory-space investigation can be interpreted as a naturalness-like argument for what lies beyond the Standard Model.
I will discuss an agnostic, model-independent analysis of baryon number violation using the power of Effective Field Theory. In my presentation, I show the contribution of dimension six and seven effective operators to ∣Δ(B−L)∣=0, 2 nucleon decays taking into account the effects of Renormalisation Group Evolution and we will find lower limits on the energy scale of each operator and correlations between different decay modes. Furthermore, I will also discuss possible UV theories responsible for the phenomena of proton decay and/or (Majorana) neutrino masses and the implications on the masses of the particles in the UV.
I will start by explaining why it is interesting and how one can quantise from first principles field theories living on the background of a bubble wall in the planar limit, i.e. a domain wall, with a particular focus on the case of spontaneous breaking of gauge symmetry. Using the tools we introduced, we can compute the average momentum transfer from transition radiation, which denotes the soft emission of radiation by a high-energetic particle passing across the wall, with a particular focus on the longitudinal polarisation of vector bosons. We find this latter one to be comparable to transverse polarisations in symmetry-breaking transitions with mild super-cooling, and dominant in broken to broken transitions with thin walls. Our results have phenomenological applications for the expansion of bubbles during first-order phase transitions. Our general framework allows for the calculation of any particle processes of interest in such translation breaking backgrounds.
Quantum entanglement is a fundamental property of quantum mechanics. Recently, studies have explored entanglement in the top-anti-top system at the Large Hadron Collider (LHC) when both the top quark and anti-top quark decay leptonically. Entanglement is detected via correlations between the polarizations of the top and anti-top and these polarizations are measured through the angles of the decay products of the top and anti-top. In this talk, I propose searching for evidence of quantum entanglement in the semi-leptonic decay channel where the final state includes one lepton, one neutrino, two b-flavor tagged jets, and two light jets from the W decay. This channel is both easier to reconstruct and has a larger effective quantity of data than the fully leptonic channel. As a result, the semi-leptonic channel is 60% more sensitive to quantum entanglement and a factor of 3 more sensitive to Bell inequality violation, compared to the leptonic channel.
Many theories beyond the Standard Model predict new phenomena, such as heavy vectors or scalar, vector-like quarks, and leptoquarks in final states containing bottom or top quarks. Such final states offer great potential to reduce the Standard Model background, although with significant challenges in reconstructing and identifying the decay products and modelling the remaining background. The recent 13 TeV pp results, along with the associated improvements in identification techniques, will be reported.
The comparable abundances of dark matter and baryons imply that the dark sector should be related to the QCD sector. In this talk, I will present a solution based on the unification of the dark and visible gauge groups. The unification guarantees common interactions and the unified gauge coupling at a high scale, which can explain the similar number densities and masses among the two sectors naturally. The idea is realized by unifying $Sp(4)_D$ dark color with $SU(3)_C$ color into $SU(7)$ and ultimately into $SU(9)$ dark grand unification.
The origin of matter in the universe from a decaying inflaton field in the process of reheating is a basic feature of all realistic inflationary models.
In this work we study the evolution of Dark Matter as a freeze-out process during reheating assuming this occurs at a minimum of a scalar potential that is expanded as a quartic power of the inflaton field. We consider the simplest scenario at the perturbative (Boltzmann) level and also the scenario where inflaton fragmentation occurs. This fragmentation is a consequence of the self-interaction of the inflaton which replaces the oscillating inflaton condensate for free inflaton particles.
In this work, we compare two SUSY extensions of the Standard Model, the MSSM and the NMSSM. Through numerical simulations, as well as utilizing MicrOMEGA's we perform a parameter space scan for each model, aiming to obtain a heavy first neutralino $M_{\chi_{1}^{0}} \in [1, 10]$ TeV to be the LSP as well as the values for its Photon Flux and Relic Density. Our research aims to provide possible values for the free Parameters in these supersymmetric models, resulting in two viable candidates for Dark Matter containing a consistent Higgs Sector with the observations of the Higgs Boson mass $M_{h} \sim 125$ GeV done by ATLAS and CMS (2012), and heavy enough to be detected by the HAWC Gamma Ray Observatory.
We study the thermal freeze-out of two-component dark matter (DM). The freeze-out in a multicomponent dark sector can be more complex and richer than the canonical single-component WIMP DM. This is owing to the relevance of processes of conversions, co-annihilations, co-scatterings, decays and self-scatterings in addition to those of annihilations and elastic scatterings, which can affect the momentum distributions of the dark sector particles and thereby the DM relic abundance. Models with suppressed elastic scatterings are known to have DM freeze-out outside of kinetic equilibrium so that a precise calculation of relic abundance needs to take into account the effect of non-thermal phase space distributions. The pseudoscalar mediated (Coy) DM model is an example of such a model. We develop a numerical tool to calculate the DM abundance in such models with a multi-component dark sector, from a solution of the full momenutum-dependent Boltzmann equations and use it to study a pseudoscalar mediated two-component DM model.
Dark matter particles in the sub-GeV range are exciting candidates as they evade the strongest constraints from direct direction using nuclear recoils. On the other hand, they are strongly constrained by the relic abundance, indirect detection with X-rays, observations of the Bullet cluster as well as searches at beam-bump and electron-positron colliders. In this talk I will show the results from frequentist and Bayesian global studies on fermionic and scalar sub-GeV dark matter coupled to a dark photon, with and without a particl-antiparticle asymmetry, and present new optimised benchmark points that can be used in future searches.
We study the coscattering mechanism in a simple Higgs portal which adds two real singlet scalars to the Standard Model. In this scenario, the lighter scalar is stabilized by a single $\mathcal{Z}_2$ symmetry and acts as the dark matter relic, whose freeze-out is driven by conversion processes. The heavier scalar becomes an unstable state which participates actively in the coscattering. We find viable parameter regions fulfilling the measured relic abundance, while evading direct detection and big-bang nucleosynthesis bounds. In addition, we discuss collider prospects for the heavier scalar as a long-lived particle at present and future detectors.
Fermilab recent results on muon's anomalous magnetic moment, improves its precision measurement, resulting in a discrepancy from SM close to five sigma. This result tightens at least one corner of the Standard Model, which otherwise has also been stretched by allowing neutrino mixing. The above could represent a window where new physics can show its nature. The SM can be seen as an effective theory at low energies and the higher energy physics would manifest discreetly in processes as NLO corrections. In this work we present a specific flavor structure within the MSSM which allows mixing within second and third families of fermions through supersymmetric one-loop diagrams. We explore the consequences of this structure in flavor violation processes for the charged leptonic sector. We found scenarios that solves the $g-2$ muon discrepancy between theory and experiment, exploring also the consequences at NLO to $BR(\tau \to \mu \gamma)$ and $BR(h^0\to \tau \mu)$; we complete the analytical calculation without invoking the {\it Mass Insertion Approximation}.
It is known that the model based on U(1)$_{L_\mu-L_\tau}$ gauge symmetry can explain not only the discrepancy between the measured value of muon $g-2$ and the theoretical prediction, but also the structure of the neutrino mass and mixings. We revisit the analysis of the mass matrix structure in the minimal U(1)$_{L_\mu-L_\tau}$ models based on the latest experimental result, where the minimal stands for the symmetry breaking caused only by a single scalar field. We find that the model called type ${\bf 2}_{+1}$, where an SU(2)$_L$ doublet scalar $\Phi_{+1}$ with the U(1)$_{L_\mu - L_\tau}$ charge $+1$ and the hypercharge $+1/2$, predicts the $\bf B_3$ texture and is marginally acceptable under the current neutrino oscillation data and cosmological observation. When the U(1)$_{L_\mu - L_\tau}$ gauge symmetry is broken by the vacuum expectation value of the standard model non-singlet representation such as $\Phi_{+1}$, there are additional contributions to the flavor-changing meson decay process and atomic parity violation via the $Z-Z'$ mixing. We newly evaluate the model-dependent constraints on the model and conclude that the type ${\bf 2}_{+1}$ model is robustly ruled out. The model is extended to have an additional vacuum expectation value of a standard model singlet scalar in order to avoid the stringent constraint from the flavor-changing meson decay. Finally, we find the allowed range of the ratio of these vacuum expectation values.
We discuss the thermal leptogenesis mechanism within the minimal gauged U(1)$_{L_\mu-L_\tau}$ model to explain the observed baryon asymmetry of the Universe (BAU).
In such framework, the phases of the Pontecorvo–Maki–Nakagawa–Sakata neutrino mixing matrix and the sum of the Standard Model neutrino masses are predictable because of a restricted neutrino mass matrix structure. Additionally, in the context of thermal leptogenesis, the BAU can be computed in terms of the three remaining free variables that parameterise the right-handed neutrino masses and their Yukawa couplings to the Higgs and lepton doublets. We identify the ranges of such parameters for which the correct BAU can be reproduced. We adopt the formalism of the density matrix equations to fully account for flavour effects and consider the decays of all the three right-handed neutrinos. Our analysis reveals that thermal leptogenesis is feasible within a wide parameter space, specifically for Yukawa couplings ranging from approximate unity to $\mathcal{O}(0.03-0.05)$ and mass of the lightest right-handed neutrino $M_1\gtrsim 10^{11-12}\,\text{GeV}$, setting a leptogenesis scale in the considered model which is higher than that of the non-thermal scenario.
We perform a global analysis of a vector-like extension of the Standard Model, which also features additional doublet and singlet scalars. The usual Yukawa interactions are forbidden in this setup by an extra U(1) global symmetry and the masses of the second and third family quarks and leptons are generated via the mixing with the vector-like sector. We identify three best-fit benchmark scenarios which satisfy the constraints imposed by the stability of the scalar potential, the perturbativity of the coupling constants, the measurement of the muon anomalous magnetic moment and the non-observation of the flavor violating tau decays. We show that dominant contributions to the muon $(g-2)$ originate in this model from the charged Higgs/neutral lepton one-loop diagrams, thus correcting an inaccurate statement than can be found in the literature. We also perform a detailed LHC analysis of the benchmark scenarios. We investigate the experimental constraints stemming from direct searches for vector-like quarks, vector-like leptons and exotic scalars. While we show that the model is not currently tested by any collider experiment, we point out that decays of a heavy Higgs boson into two tau leptons may offer a smoking gun signature for the model verification in upcoming runs
at the LHC.
Flavor deconstruction refers to ultraviolet completions of the Standard Model where the gauge group is split into multiple factors under which fermions transform non-universally. We propose a mechanism for charging same-family fermions into different factors of a deconstructed gauge theory in a way that gauge anomalies are avoided. The mechanism relies in the inclusion of a strongly-coupled sector, responsible of both anomaly cancellation and the breaking of the non-universal gauge symmetry. As an application, we propose different flavor deconstructions of the Standard Model that, instead of complete families, uniquely identify specific third-family fermions. All these deconstructions allow for a new physics scale that can be as low as few TeV and provide an excellent starting point for the explanation of the Standard Model flavor hierarchies.
The discovery of the Higgs boson with the mass of about 125 GeV completed the particle content predicted by the Standard Model. Even though this model is well established and consistent with many measurements, it is not capable to solely explain some observations. Many extensions of the Standard Model addressing such shortcomings introduce additional Higgs bosons, beyond-the-Standard-Model couplings to the Higgs boson, or new particles decaying into Higgs bosons. In this talk, the latest searches in the Higgs sector by the ATLAS experiment are reported, with emphasis on the results obtained with the full LHC Run 2 dataset at 13 TeV.
We discuss the accumulating evidence for a new Higgs boson at $\sim 95$ GeV and how it could be realized in simple Higgs sector extensions. We discuss the physics implications for the LHC and future $e^+e^-$ colliders.
The direct production of electroweak SUSY particles, including sleptons, charginos, and neutralinos, is a particularly interesting area with connections to dark matter and the naturalness of the Higgs mass. The small production cross-sections and challenging experimental signatures lead to difficult searches. This talk will highlight the most recent results of searches performed by the ATLAS experiment for supersymmetric particles produced via electroweak processes, including analyses targeting small mass splittings between SUSY particles. Recent results involving the combination of searches and in the context of the pMSSM are also presented.
A wide variety of searches for Supersymmetry have been performed by experiments at the Large Hadron Collider. In this talk, we focus on searches for electroweak production of Supersymmetric particles as well as third generation Supersymmetric particles. Some analyses are optimized for Supersymmetric particles in compressed spectra. The results are obtained from the proton-proton collision data with luminosity up to 138 fb-1 at the center of mass energy of 13 TeV collected during the LHC Run 2.
Supersymmetry (SUSY) provides elegant solutions to several problems in the Standard Model, and searches for SUSY particles are an important component of the LHC physics program. Naturalness arguments favour supersymmetric partners of the gluons and third-generation quarks with masses light enough to be produced at the LHC. This talk will present the latest results of searches conducted by the ATLAS experiment which target gluino and squark production, including stop and sbottom, in a variety of decay modes within RPC SUSY.
We discuss the possibility that light new physics in the top quark sample at the LHC can be found by investigating with greater care well known kinematic distributions, such as the invariant mass mbℓ of the b-jet and the charged lepton in fully leptonic ttbar events. We demonstrate that new physics can be probed in the rising part of the already measured mbℓmbℓ distribution. To this end we analyze a concrete supersymmetric scenario with light right-handed stop quark, chargino and neutralino. The corresponding spectra are characterized by small mass differences, which make them not yet excluded by current LHC searches and give rise to a specific end-point in the shape of the mbℓ distribution. We argue that this sharp feature is general for models of light new physics that have so far escaped the LHC searches and can offer a precious handle for the implementation of robust searches that exploit, rather than suffer from, soft bottom quarks and leptons. Recasting public data on searches for new physics, we identify candidate models that are not yet excluded. For these models we study the mbℓ distribution and derive the expected signal yields, finding that there is untapped potential for discovery of new physics using the mbℓ distribution.
The search for weakly interacting particles is one of the main objectives of the high luminosity LHC. In the Minimal Supersymmetric Extension of the Standard Model (MSSM), these particles include the lightest neutralino, which is a good Dark Matter candidate and whose relic density may be fixed to realistic values through its co-annihilation with the second lightest neutralino and lightest chargino. Moreover, its direct Dark Matter detection rate is suppressed for the same region of parameters in which the radiative decay of the second lightest neutralino into a photon and the lightest neutralino is enhanced. This motivates the search for radiatively decaying neutralinos, which, however, suffers from strong backgrounds. In this work we provide an analysis of the reach of the LHC in the search for these radiatively decaying particles by means of cut-based and machine learning methods, defining the LHC discovery potential in this well motivated region of parameters in the high luminosity era.
Searches for anomalous neutral triple gauge boson couplings (NTGCs) provide important tests for the gauge structure of the standard model. In SMEFT NTGCs appear at the level of dimension-8 operators. We point out that the complete matching of UV models requires four different CP-conserving $d=8$ operators and that the single CPC $d=8$ operator, most commonly used by the experimental collaborations, does not cover all vertices. Despite stringent experimental constraints on NTGCs, limits on the scale of UV models are relatively weak, because their contributions are doubly suppressed, being $d=8$ and 1-loop. We suggest a series of benchmark UV scenarios suitable for interpreting searches for NTGCs in the upcoming LHC runs and discuss current and future limits.
We discuss heavy particles that can be used to pin down the faithful Standard Model (SM) gauge group and their patterns in the SM effective field theory (SMEFT). These heavy particles are not invariant under a specific Z6 subgroup of SU(3)c ×SU(2)L ×U(1)Y, which however acts trivially on all the SM particles, hence the faithful SM gauge group remains undetermined. Different realizations of the faithful SM gauge group correspond to different spectra of heavy particles, and they also correspond to distinct sets of line operators with one-form global symmetry acting on them. We show that the heavy particles not invariant under the Z6 group cannot appear in tree-level ultraviolet completions of SMEFT, this enforces us to consider one-loop UV completions of SMEFT to identify the Z6 non-invariant heavy particles. We demonstrate with examples that correlations between Wilson coefficients provide an efficient way to examine models with Z6 non-invariant heavy particles. Finally, we prove that all the scalars that can trigger electroweak symmetry breaking must be invariant under the Z6 group, hence they cannot be used to probe the faithful SM gauge group.
Composite Higgs models with a fermionic UV completion predict unusual top partners and an extended scalar sector. We present a particular model which predicts color octet and color neutral fermions as as a color triplet scalar. This model has an additional `baryon' number implying the stability of the lightest resonance which can serve as a dark matter candidate. We discuss the LHC phenomenology of this model and show that it might be confused with supersymmetric models at first glance.
Many different theories beyond the Standard Model (SM) predict that new physics will manifest itself by decaying into final states involving leptons. Leptoquarks are predicted by many new physics theories to describe the similarities between the lepton and quark sectors of the SM. Right-handed Ws and heavy-neutrinos are also predicted by many extensions of the SM in the gauge sector, and lepton flavour violation could manifest itself by decays of new gauge bosons into leptons of different flavours. This talk will present the most recent 13 TeV results on the searches for leptoquarks with the ATLAS detector, covering flavour-diagonal and cross-generational final states, as well as the latest searches for lepton-flavour violating Z' and heavy neutrinos arising from left-right symmetric models.
The presence of a non-baryonic Dark Matter (DM) component in the Universe is inferred from the observation of its gravitational interaction. If Dark Matter interacts weakly with the Standard Model (SM) it could be produced at the LHC. The ATLAS Collaboration has developed a broad search program for DM candidates in final states with large missing transverse momentum produced in association with other SM particles (light and heavy quarks, photons, Z and H bosons, as well as additional heavy scalar particles) and searches where the Higgs boson provides a portal to Dark Matter, leading to invisible Higgs decays. The results of recent searches on 13 TeV pp data from the LHC, their interplay and interpretation will be presented.
Determination of the nature of dark matter is one of the most fundamental problems of particle physics and cosmology. This talk presents recent searches for dark matter particles from the CMS experiment at the Large Hadron Collider. The results are based on proton-proton collisions recorded at sqrt(s) = 13 TeV with the CMS detector.
Dark Matter models that employ a vector portal to a dark sector are usually treated as an effective theory that incorporates kinetic mixing of the photon with a new U(1) gauge boson, with the Z boson integrated out. However, a more complete theory must employ the full SU(2)L×U(1)×U(1)' gauge group, in which kinetic mixing of the Z boson with the new U(1)' gauge boson is taken into account. The importance of the more complete analysis is demonstrated by an example where the parameter space of the effective theory that yields the observed dark matter relic density conflicts with a suitably defined electroweak ρ parameter that is deduced from a global fit to Z physics data.
We explore the Large Hadron Collider (LHC) constraints on dark matter models (DM) based on a new $\mathrm{U(1)}^{\prime}$ symmetry. Within this framework, DM production is mediated by a spin-1 or a scalar resonance. We focus on ATLAS and CMS experimental searches for spin-1 resonances with decays to jets, $b$-jets, top quarks, or DM, and the resonant production of a scalar that decays into a pair of DM particles. Our approach involves integrating these experimental results into the latest version (v3) of the SModelS tool, allowing us to quickly test the two-mediator DM (2MDM) parameter space. SModelS also provides the tools for combining approximately uncorrelated results, which we apply to enhance the LHC sensitivity to the 2MDM.
We reappraise the viability of asymmetric dark matter (ADM) realized as a Dirac fermion coupling dominantly to the Standard Model fermions. Treating the interactions of such a DM particle with quarks/leptons in an effective-interactions framework, we derive updated constraints using mono-jet searches from the Large Hadron Collider (LHC) and mono-photon searches at the Large Electron-Positron (LEP) collider. The constraint of efficient annihilation of the symmetric part of the ADM, as well as other observational constraints are synthesized to produce a global picture. Consistent with previous work, we find that ADM with mass in the range 1–100 GeV is strongly constrained, thus ruling out its best motivated mass range. However, we find that leptophilic ADM remains allowed for equal to more than 10 GeV DM, including bounds from colliders, direct detection, and stellar heating. We forecast that the Future Circular Collider for electron-positron collisions (FCC-ee) will improve sensitivity to DM-lepton
interactions by almost an order of magnitude.
Conventional methods for elucidating the behavior of Dark Matter (DM), such as effective field theory (EFT) and simplified models, have inherent limitations, including their limited applicability in LHC searches for DM and lack of generality, respectively. In this study, we propose a hybrid formulation aimed at reconciling these shortcomings by addressing both generality and applicability at colliders. To this end, we introduce an EFT that incorporates DM and two scalar mediators, thereby enabling a richer phenomenology. Moreover, we formulate the theory in a non-linear phase, thereby allowing for additional representations of the scalar mediators.
To demonstrate the efficacy of this framework, we will present a comparative analysis with well-known simplified models during the talk.
We present searches from the CMS experiment, performed with data collected during LHC Run 2 at a centre-of-mass energy of 13 TeV, for rare Higgs bosons decays into light pseudoscalars. A variety of final states are explored, probing both boosted and resolved topologies.
We study the interaction between the inert Higgs doublet (IDM) dark matter and a vector-like SU(2) triplet lepton (VLL), both of which are Z2-odd. The vector current of the VLL with the Z-boson rules out a fermionic or two-component dark matter scenario. However, a compressed mass spectrum and a sufficiently small Yukawa coupling allows co-annihilation and late decay of the VLL into the IDM sector, affecting the relic density of the pseudoscalar darkmatter. The same two factors enable displaced decay of the VLL states, providing novel signatures involving hadronically quiet displaced multi-lepton final states. Such signatures to probe the model are studied at the 14 and 27 TeV LHC, as well as the 100 TeV FCC-hh. In addition to being detectable at the CMS/ATLAS experiments, if the new particles have sub-100 GeV masses,
signals can also be seen at the proposed MATHUSLA detector
We analyze possible signatures of an ALP with masses above $\sim 400$ GeV at the (HL-)LHC in the $t \bar t$ decay channel. In particular, we demonstrate that such an ALP could be distinguished from a CP-even Higgs boson with the same mass and the same $t \bar t$ cross section with the help of $m_{tt}$ distributions. We obtain new limits on the effective ALP couplings to top quarks and gluons.
In this talk we investigate the capability of the new ATLAS searches for
$A \to ZH$ decays in $ell^+ \ell^- t \bar t$ and $\nu \nu b \bar b$
final states to probe the electroweak phase transition in the early
Universe. In the framework of the Two Higgs Doublet Model (2HDM), we
investigate the impact of the new searches on the 2HDM parameter space,
paying special attention to parameter space regions that predict a
strong first order electroweak phase transition. We discuss the
complementarity with other LHC searches, and we analyze the interplay of
collider searches and space based gravitational wave experiments. We
furthermore show that the $3\sigma$ excess observed at $m_A = 650$~GeV
and $m_H = 450$~GeV can be described in the 2HDM, where the preferred
parameter space falls within the region suitable for a realization of a
strong first-order phase transition. The GW signal produced during the
transition in the early universe might be in reach of LISA. Finally, we
present a python package for the exploration of the 2HDM parameter space
that can be used to confront the model with the most significant
theoretical and experimental constraints.
As in arXiv:2307.04255, we consider a radically modified form of supersymmetry (called susy here to avoid confusion), which initially combines standard Weyl fermion fields and primitive (unphysical) boson fields. A stable vacuum then requires that the initial boson fields, whose excitations would have negative energy, be transformed into three kinds of scalar-boson fields: the usual complex fields $\phi$, auxiliary fields $F$, and real fields $\varphi$ of a new kind (with degrees of freedom and gauge invariance preserved under the transformation). The requirement of a stable vacuum thus imposes Lorentz invariance, and also immediately breaks the initial susy -- whereas the breaking of conventional SUSY has long been a formidable difficulty. Even more importantly, for future experimental success, the present formulation may explain why no superpartners have yet been identified: Embedded in an $SO(10)$ grand-unified description, most of the conventional processes for production, decay, and detection of sfermions are excluded, and the same is true for many processes involving gauginos and higgsinos. This implies that superpartners with masses $\sim 1$ TeV may exist, but with reduced cross-sections and modified experimental signatures. For example, a top squark (as redefined here) will not decay at all, but can radiate pairs of gauge bosons and will also leave straight tracks through second-order (electromagnetic, weak, strong, and Higgs) interactions with detectors. The predictions of the present theory include (1) the dark matter candidate of our previous papers, (2) many new fermions with masses not far above 1 TeV, and (3) the full range of superpartners with a modified phenomenology.
Superstring flux compactifications can stabilize all moduli while
leading to an enormous number of vacua solutions,
each leading to different $4-d$ laws of physics.
While the string landscape provides at present the only plausible explanation
for the size of the cosmological constant, it may also predict the form of
weak scale supersymmetry which is expected to emerge.
Rather general arguments suggest a power-law draw to large soft terms,
but these are subject to an anthropic selection of not-too-large a
value for the weak scale. The combined selection allows to compute relative
probabilities for the emergence of supersymmetric models from the landscape.
Models with weak scale naturalness appear most likely to emerge since
they have the largest parameter space on the landscape.
For finetuned models such as high scale SUSY or split SUSY,
the required weak scale finetuning shrinks their parameter space to
tiny volumes, making them much less likely to appear compared to natural models.
Probability distributions for sparticle and Higgs masses from natural models
show a preference for Higgs mass $m_h\sim 125$ GeV with sparticles typically
beyond present LHC limits, in accord with data.
From these considerations, we briefly describe how natural SUSY is expected
to be revealed at future LHC upgrades.
In this talk, I will present recent results on precision calculations for the squark-(anti)squark production processes at the LHC with a center-of-mass energy of $\sqrt{S} = 13.6$ TeV in the framework of the Minimal R-symmetric Supersymmetric Standard Model (MRSSM). In contrast to the Minimal Supersymmetric Standard Model (MSSM), the MRSSM has a higher degree of symmetry, which affects, in particular, the production mechanisms. The known next-to-leading order (NLO) results are improved by threshold resummation, carried out using the direct QCD method, and reach next-to-next-to-leading logarithmic (NNLL) accuracy. New calculations required for the one-loop matching coefficients in the relevant production channels will be reported. The results show a significant suppression of the cross sections compared to the MSSM, effectively allowing lighter squark masses to be compatible with current LHC searches.
The split-supersymmetry method was proposed to address the naturalness (or hierarchy) problem in physics beyond the standard model without the need for a light supersymmetric spectrum. This talk will address this mechanism for supersymmetry breaking within a finite grand unification model, particularly in the $SU(3)^3$ model, motivated by a scenario of anomaly-mediated SUSY breaking. Additionally, it will analyze the combined effect of implementing this mechanism for supersymmetry breaking and the existence of an intermediate scale in the breaking of the unification group on the values of the masses of the third-family quarks.
Rather general considerations from the string landscape imply a statistical draw to large soft terms which must be tempered by a pocket-universe derived value of the weak scale within the ABDS window. The statistical approach realizes Douglas' notion of stringy naturalness leading to mh~125 GeV and sparticles somewhat or well beyond present LHC search limits. Light higgsinos ~100-350 GeV are expected and may emerge at LHC via soft dilepton signatures from higgsino pair production. As for dark matter, we expect mainly DFSZ SUSY axions along with a smattering of higgsino-like WIMPs.
In the context of the Swampland program, the Distance Conjecture predicts an infinite tower of states becoming massless at infinite distance in moduli spaces of string compactifications. This is widely believed to be a general feature of quantum gravity, but it is difficult to prove in full generality. On the other hand, the moduli spaces of maximally and half-maximally supersymmetric theory are coset spaces of the globally symmetric type, which are mathematically fairly well understood. In this work, we provide a framework to study systematically the infinite distance limits in these simple cases, and use this knowledge to argue for the Distance Conjecture in this subset of theories.
Since their discovery in the 90’s, multiple string dualities have been discovered, relating seemingly different perturbative and non-perturbative regimes of the space of parameters (or moduli space), in such a way that in its asymptotic regions one is usually able to work in some duality frame with perturbative control (e.g. large volume and small string coupling). On the other hand, over the recent years, the Swampland Program has tried to state various criteria (or conjectures) that EFT consistent with QG must satisfy. The Swampland Distance Conjecture states that moving towards an asymptotic limit of moduli space is accompanied by the existence of a tower of states becoming light. At the same time, the Emergent String Conjecture constrains the possible types of these light towers. We use this to restrict the possible moduli-dependences of the different towers and QG cut-off (or Species Scale) of the different asymptotic regimes. Under certain assumptions, this enables a classification in terms of a finite list of polytopes, which in turn allows us to understand how the different duality frames are globally “glued” together in the moduli space, as well as their ranges of validity. We illustrate this for 9d theories with different amounts of supersymmetry.
We study limits of vanishing Yukawa couplings in Quantum Gravity, using as a laboratory type IIA orientifolds. We show that in the limit Y → 0 there are some towers (dubbed gonions) that become asymptotically massless, while at the same time, the kinetic term of some chiral fields becomes singular. For limits parametrised by a large complex structure saxion u, Yukawa couplings have a behavior of the form Y ∼ 1/u^r. Moreover, some of the gauge couplings associated with the Yukawa vanish in this limit. The lightest gonion scales are of order mgon ∼ g^s with s > 1, verifying the magnetic WGC with room to spare and with no need of its tower/sublattice versions. All these results may be very relevant for phenomenology, given that some of the Yukawa couplings in the Standard Model are very small.
I will discuss supersymmetric AdS_3 flux vacua of massive type-IIA supergravity on G2 orientifolds, focusing on (non) scale separated configurations at large volume and weak-coupling, even highly anisotropic. In addition, inspired by the desire of finding all possible flux choices which give rise to the aforementioned AdS_3 scale-separated configurations, I will discuss some recent developments concerning a systematic study of M-theory and type-II flux vacua in three dimensions, including gauge and metric fluxes and admitting a description in terms of three-dimensional gauged supergravitites with half-maximal supersymmetry.
This study investigates the decay of the Kaluza-Klein vacuum mediated by instanton solutions with singularities. For the Kaluza-Klein vacuum, there exists a non-perturbative decay channel where spacetime is overwhelmed by the bubble of nothing (BoN), which has no degrees of freedom therein. The instanton solution mediating this decay is the BoN instanton, which is the Euclideanized 5D Schwarzschild black hole solution. In general discussions, the periodicity of imaginary time is fixed to appropriate values at the position of the event horizon to avoid singularities. However, we relax this smoothness condition and calculate the contribution of the conical singularity to the Euclidean action based on the conical deficit regularization. These contributions are always negative and tend to decrease the Euclidean action. Thus, if correct, decay via singular instanton solutions may be a more dominant process. Additionally, we reconstruct the bounce action using thermodynamic functions and attempt a thermodynamic interpretation of the catalytic effect mentioned above.
Long-range angular correlations among particles may uncover physics
beyond the Standard Model, such as Hidden Valley (HV) scenarios. We particularly investigate a QCD-like sector, where HV matter coupled with QCD partonic cascades, may enhance azimuthal correlations among final-state particles. Our examination at the detector level concentrates on discerning these signals at future e+e- colliders, which provide a cleaner experimental setting than the Large Hadron Collider (LHC). Particularly, the detection of ridge formations in the two-particle correlation function could suggest the existence of new physics phenomena.
We discuss the experimental prospects for measuring differential observables in b-quark and c-quark pair production at the International Linear Collider (ILC) baseline energies, 250 and 500 GeV. The study is based on full simulation and reconstruction of the International Large Detector (ILD) concept. Two gauge-Higgs unification models predicting new high-mass resonances beyond the Standard Model are discussed. These models predict sizable deviations of the forward-backward observables at the ILC running above the mass and with longitudinally polarized electron and positron beams. The capability of the ILC to probe these models via high-precision measurements of the forward-backward asymmetry is discussed.
Alternative scenarios at other energies and beam polarization schemes are also discussed, extrapolating the estimated uncertainties from the two baseline scenarios.
We examine the detection prospects of new Standard Model (SM)-neutral vector bosons (Z′) that couple exclusively to leptons at the Future Circular Collider (FCC-ee), by performing parton level and detector level analyses. We show that FCC-ee can significantly extend the unprobed parameter space in the kinematically allowed mass range, and competes with other proposed lepton collider options (MuC3 and CLIC) in the mass range between 1-365 GeV.
FlexibleSUSY is a framework for automating computations of physical quantities in BSM theories. We show an extension of FlexibleSUSY which allows us to define and add new observables. The extension has already been used to include Charged Lepton Flavor Violation (CLFV) observables and now further observables can be added straightforwardly.
The talk is split into two parts. We explain how to define new observables such that their automatic computation in any applicable BSM model becomes possible via the new NPointFunctions extension. In addition, we discuss the studies where this package was already applied. This illustrates the features and provides code snippets that may be used as a starting point for implementing further observables.
We develop a numerical technique for the optimal extraction of the new physics (NP) couplings applicable to any collider process, without any simplifying assumption. This approach also provides a way to compare with the NP estimates derived using standard $\chi^2$ analysis and can be used to gauge the advantages of various modalities of collider design, such as centre of mass energy, beam polarization as well as kinematical cuts. We illustrate the techniques and arguments by considering the pair production of heavy charged fermions at an $e^+e^-$ collider in presence of SM background.
The particles composing the dark matter are thought to be distributed in haloes around the galaxies and then, they can be detected on Earth-based very sensitive instruments if they couple to normal matter other than gravitationally. However, the many unknowns and uncertainties in the properties of the particles and their distribution in the galaxy affect these direct searches of the dark matter. Sensitivities have been steadily improving for about forty years, profiting from the development of new detection strategies, application of a variety of target nuclei, and improving the ultra-low-radioactive background techniques. I will make a personal selection of detection techniques and experimental results to review the status and prospects of these searches with the focus on WIMP (Weakly Interacting Massive Particles) dark matter candidates.
One of those detection techniques is particularly interesting because of the long-standing puzzling result of DAMA/LIBRA experiment, which has observed for more than twenty years an annual modulation in the detection rate of their NaI(Tl) detectors. The observed modulation shares all the features expected for the galactic dark matter signal. However, no other experiment has observed any hint supporting this interpretation of the DAMA/LIBRA result, and it seems very difficult to reconcile the plethora of negative results from different experiments (using different targets and techniques) with the DAMA/LIBRA signal. However, most sensitive experiments cannot be compared with DAMA/LIBRA result in a model-independent way because of the unknowns and uncertainties in the model parameters involved in such a comparison. Only recently, three-sigma sensitivity to DAMA/LIBRA result is at hand using the same target material, NaI, which allows to cancel all the signal dependences on the particle dark matter model and the dark halo model, and then, it enables a model independent testing. The status of the testing of the DAMA/LIBRA result at present, as well as a revision of the possible systematics involved and the sensitivity prospects for the near future will be presented with the focus on the ANAIS experiment, taking data at the Canfranc Underground Laboratory.
DAMA/LIBRA observation of an annual modulation in the low energy detection rate compatible with that expected for dark matter has accumulated evidence for more than twenty years. It is the only hint about a positive identification of the dark matter, but it is in strong tension with the negative results of other experiments. However, this comparison depends on the models assumed for the dark matter particle and its velocity distribution in the galactic halo. ANAIS-112, using the same target material than DAMA/LIBRA, NaI(Tl), can perform a model independent test. ANAIS-112 is taking data smoothly with excellent performance since August 2017, and is leading the efforts within the international dark matter community with this goal, according to the last released results. We will present the results of a reanalysis of the first 3 years data using new filtering protocols based on machine-learning techniques, which are compatible with the absence of modulation and incompatible with DAMA/LIBRA for a sensitivity of almost 3σ C.L., with the potential to reach a 5σ level by the end of 2025. The main systematics in the comparison between DAMA/LIBRA result and other experiments using NaI(Tl) is the scintillation quenching factor. The impact of different scintillation quenching factors in the comparison between ANAIS-112 and DAMA/LIBRA will also be addressed in the talk. Finally, the present status and prospects of the experiment will be discussed.
As nuclear recoil direct detection experiments carve out more and more dark matter parameter space in the WIMP mass range, the need for searches probing lower masses has become evident. Since lower dark matter masses lead to smaller momentum transfers, we can look to the low momentum limit of nuclear recoils: phonon excitations in crystals. Single phonon experiments promise to eventually probe dark matter masses lower than 1 MeV. However the slightly higher mass range of 10-100 MeV can be probed via multiphonon interactions and importantly, do not require as low of experimental thresholds to make a detection. In this work, we analyze dark matter interacting via a pseudoscalar mediator, which leads to spin-dependent scattering into multiphonon excitations. We consider several likely EFT operators and describe the future prospects of experimentation for finding dark matter via this method. Our results are implemented in the python package DarkELF and can be straightforwardly generalized to other spin dependent EFT operators.
Direct-detection experiments seek signals generated by dark matter particles interacting with the microscopic constituents of detector materials.
In our work, we combine a non-relativistic effective theory for DM-electron interactions with the linear response theory to describe the scattering of sub-GeV DM particles in Si, Ge, Xe and Ar detectors.
Within this formalism, the detector response to an arbitrary DM-electron interaction is described in terms of generalised susceptibilities, which extend the notion of dielectric function to general DM-detector couplings.
It can be shown that due to the requirement of analyticity and causality, some of those generalised susceptibilities, and thus the associated scattering rates, are bounded from above.
We compare the expected scattering rates in currently used detector materials with our predicted theoretical upper bound and explore the properties an optimal material should have in order to saturate this bound and thus maximize the possible detector response.
In this work we present a modular procedure for estimating the dark matter (DM) parameters from DM direct detection experiments. We use machine learning techniques to perform a Bayesian analysis to determine the discovery potential and to estimate the model parameters without the need of assuming a likelihood functional form. Since each dataset can be trained individually, one of the main advantages of the method is that the inclusion of new experimental data is simple and fast. This allows to include, combine, or remove datasets, either data representations or results from different detectors, using already trained algorithms in a modular fashion. In order to illustrate this method we consider the case of WIMP DM within the framework of effective field theory (EFT) to describe the DM-nucleus scattering cross section in a XENON-like experiment. We show the results in the DM mass, coupling-coefficient amplitude and phase space of the EFT operators.
We present a new global analysis of the charged lepton flavor violating sector of low-energy and SM effective field theories, performing a global fit beyond the most common consideration of one operator at a time. We investigate how much present data is able to constrain the full parameter space, inspecting the potential flat directions that hinder this task, and discuss how the bounds dramatically change when considering a global picture.
The search for lepton flavour violation is regarded as one of the main roads in the quest for New Physics beyond the Standard Model. The MEG II experiment searches for the decay $\mu ^+ \rightarrow \textrm{e}^+ \gamma$ with the world's most intense continuous muon beam at the Paul Scherrer Institute and high-performance detectors, aiming at ten times higher sensitivity than the previous MEG experiment. The result with the first dataset (taken in 2021) was published and the combination of this result and the limit obtained by MEG gives $\mathcal {B} (\mu ^+ \rightarrow {\textrm{e}}^+ \gamma )$ $<$ $3.1 \times 10^{-13}$ (90$\%$ CL), which is the most stringent limit to date. The MEG II experiment took data in 2022 and 2023 collecting a ten times larger data statistics than in 2021 and a more than twenty-fold increase in data statistics is anticipated by 2026 to reach the sensitivity goal. The latest results from the MEG II experiment will be presented.
We propose a method to explore the flavor structure of quarks and leptons with reinforcement learning, which is a type of machine learning. As a concrete model, we focus on the Froggatt-Nielsen model with $U(1)$ flavor symmetry. By training neural networks on the $U(1)$ charges of quarks and leptons, the agent finds 21 models to be consistent with experimentally measured masses and mixing angles of quarks and leptons. In particular, The normal ordering of neutrino masses is well fitted with the current experimental data in contrast to the inverted ordering. Moreover, a specific value of effective mass for the neutrinoless double beta decay and a sizable leptonic CP violation. Our finding results indicate that the reinforcement learning can be a new method for understanding the flavor structure. The reference is JHEP12(2023)021 (arXiv:2304.14176 [hep-ph]).
We compute the one-loop contribution to the $\bar{\theta}$-parameter of an axion-like particle (ALP) with CP-odd derivative couplings. Its contribution to the neutron electric dipole moment is shown to be orders of magnitude larger than that stemming from the one-loop ALP contributions to the up- and down-quark electric and chromoelectric dipole moments. This strongly improves existing bounds on ALP-fermion CP-odd interactions, and also sets limits on previously unconstrained couplings. The case of a general singlet scalar is analyzed as well. In addition, we explore how the bounds are modified in the presence of a Peccei-Quinn symmetry.
This talk will present a one-loop UV/IR dictionary providing a mapping between the B-conserving dimension-6 SMEFT and the linear SM extensions. These are exotic multiplets that couple linearly to the SM through renormalisable interactions. Our work leverages recent progress in computational tools which automate the one-loop matching procedure. The utility of our map in assessing the implications of dimension-6 operator measurements on simplified models and vice versa is illustrated with an example model interpretation of a fit to electroweak precision data.
The event rates and kinematics of Higgs boson production and decay processes at the LHC are sensitive probes of possible new phenomena beyond the Standard Model (BSM). This talk presents precise measurements of Higgs boson production and decay rates, obtained using the full Run 2 and partial Run 3 pp collision dataset collected by the ATLAS experiment at 13 TeV and 13.6 TeV. These include total and fiducial cross-sections for the main Higgs boson processes as well as branching ratios into final states with bosons and fermions. Differential cross-sections in a variety of observables are also reported, as well as a fine-grained description of the Higgs boson production kinematics within the Simplified Template Cross-section (STXS) framework.
FlexibleSUSY is a framework for an automated computation of physical quantities in non-supersymmetric and supersymmetric models starting from the most basic building blocks, namely the particle content and the Lagrangian. Among a plethora of observables that it supports it is also capable of computing decay widths of Higgs sector particles with precision comparable to experimental measurements. In this talk I will discuss the recently created interface between FlexibleSUSY and HiggsTools/Lilith that allows to asses the global agreement of a BSM model Higgs sector with experimental data. This provides a fully automatized chain leading directly from a user defined BSM model to the quantified (in terms of p-value) viability of that model.
In a supersymmetric theory, large mass hierarchies can lead to large uncertainties in fixed-order calculations of the SM-like Higgs mass. A reliable prediction is then obtained by performing the calculation in an effective field theory (EFT) framework, involving the matching to the full supersymmetric theory at the high scale to include contributions from the heavy particles, and a subsequent renormalization-group running down to the low scale.
In my talk, I report on the prediction of the SM-like Higgs mass within the CP-violating Next-to-Minimal Supersymmetric extension of the SM (NMSSM) in a scenario where all non-SM particles feature TeV-scale masses. The matching conditions are calculated at full one-loop order using two approaches. These are the matching of the quartic Higgs couplings as well as of the SM-like Higgs pole masses of the low- and high-scale theory. A comparison between the two methods allows for an estimate of the size of terms suppressed by the heavy mass scale that are neglected in a pure EFT calculation as given by the quartic-coupling matching. Furthermore, I will discuss the different sources of uncertainty which enter the calculation as well as the effect of CP-violating phases on the Higgs mass prediction. The matching calculation is implemented in a new version of the public program package NMSSMCALC.
This talk presents precise measurement of the properties of the Higgs boson, including its mass, total width, spin, and CP quantum number. The measurements are performed in various Higgs boson production and decay modes, as well as their combinations. Observation of deviations between these measurements and Standard Model (SM) predictions would be a sign of possible new phenomena beyond the SM
In this talk I will present results from two new GAMBIT studies of LHC searches for supersymmetry, the largest such GAMBIT studies to date. We focus on LHC searches for charginos and neutralinos, and consider both scenarios with and without a gravitino as the lightest supersymmetric particle. By running full event simulations at each sampled MSSM parameter point, we carry out detailed and computationally expensive fits that combine 40 different ATLAS and CMS searches. Our results provide a global picture of the impact current LHC results have on the space of non-simplified scenarios with light neutralinos and charginos.
The most recent searches by the ATLAS and CMS Collaborations in final states with soft leptons and missing transverse energy show mild excesses predominantly associated with dilepton invariant masses of about 10-20 GeV, which can result from decays of electroweakinos that are heavier than the lightest neutralino by $\mathcal{O}(10)$ GeV. On the other hand, these analyses are insensitive to electroweakino mass splittings smaller than about 5 GeV. In previous work, we demonstrated that while recent searches in the monojet channel can exclude some of the smallest $\mathcal{O}(1)$ GeV mass splitting configurations for electroweakinos, they also exhibit excesses that can overlap with the soft-lepton excesses in certain models, including a simplified scenario with pure higgsinos. In this work we dive deeper into these excesses, studying the analyses in detail and exploring an array of models that go beyond the simplified scenarios considered by the experimental collaborations. We show that, in the Minimal Supersymmetric Standard Model, the overlapping excesses are not unique to the pure-higgsino limit, instead persisting in realistic parameter space featuring a bino-like lightest supersymmetric particle with some wino admixture. On the other hand, for the Next-to-Minimal Supersymmetric Standard Model with a singlino-like lightest supersymmetric particle and higgsino-like next-to-lightest supersymmetric particle(s), the excess in the two-lepton channel fits rather well with the parameter space predicting the correct relic abundance through freeze out, but the monojet fit is much poorer. Interestingly, the excesses either do not overlap or do not exist at all for two non-supersymmetric models seemingly capable of producing the correct final states.
We discuss the various excesses observed consistently between ATLAS and CMS in the search for $pp \to \tilde\chi_2^0 \tilde\chi_1^\pm$. We analyze the MSSM scenarios that can accommodate these excesses, as well as their phenomenological implications for current and future colliders.
We unveil blind spot regions in dark matter (DM) direct detection (DMDD), for weakly interacting massive particles with a mass around a few hundred~GeV that may reveal interesting photon signals at the LHC. We explore a scenario where the DM primarily originates from the singlet sector within the $Z_3$-symmetric Next-to-Minimal Supersymmetric Standard Model (NMSSM). A novel DMDD spin-independent blind spot condition is revealed for singlino-dominated DM, in cases where the mass parameters of the higgsino and the singlino-dominated lightest supersymmetric particle (LSP) exhibit opposite relative signs (i.e., $\kappa < 0$), emphasizing the role of nearby bino and higgsino-like states in tempering the singlino-dominated LSP. Additionally, proximate bino and/or higgsino states can act as co-annihilation partner(s) for singlino-dominated DM, ensuring agreement with the observed relic abundance of DM. Remarkably, in scenarios involving singlino-higgsino co-annihilation, higgsino-like neutralinos can distinctly favor radiative decay modes into the singlino-dominated LSP and a photon, as opposed to decays into leptons/hadrons. In exploring this region of parameter space within the singlino-higgsino compressed scenario, we study the signal associated with at least one relatively soft photon alongside a lepton, accompanied by substantial missing transverse energy and a hard initial state radiation jet at the LHC. In the context of singlino-bino co-annihilation, the bino state, as the next-to-LSP, exhibits significant radiative decay into a soft photon and the LSP, enabling the possible exploration at the LHC through the triggering of this soft photon alongside large missing transverse energy and relatively hard leptons/jets resulting from the decay of heavier higgsino-like states.
To maximise the information obtained from various independent new physics searches conducted at the LHC, it is imperative to contemplate the combination of multiple analyses. We consider a simplified SUSY scenario with all particles but one squark flavor and a bino-like neutralino decoupled to showcase the exclusion power gained by combining uncorrelated signal regions from different searches. This study includes strong squark pair production, associated squark-neutralino production, as well as weak neutralino pair production. We find that considering associated and strong production mwchanisms together significantly impacts the mass limit, while contributions from the weak production are insignificant in the context of current exclusion limits. In addition, we demonstrate that the combination of uncorrelated signal regions as assessed from the recent TACO approach substantially pushes exclusion limits towards higher masses, relative to the bounds derived from the most sensitive individual analyses.
Carlos Wagner (Argonne National Laboratory)
Jenny List (DESY)
Karl Jakobs (Freiburg)
Greg Landsberg (Brown Univ.)
Antonio Delgado (Notre Dame)
Dark sectors, ALPs, Long Lived
Self-organized free afternoon
Various theories beyond the Standard Model predict new, long-lived particles with unique signatures which are difficult to reconstruct and for which estimating the background rates is also a challenge. Signatures from displaced and/or delayed decays anywhere from the inner detector to the muon spectrometer, as well as those of new particles with fractional or multiple values of the charge of the electron or high mass stable charged particles are all examples of experimentally demanding signatures. The talk will focus on the most recent results using 13 TeV pp collision data collected by the ATLAS detector.
Many models beyond the standard model predict new particles with long lifetimes. These long-lived particles (LLPs) decay significantly displaced from their initial production vertex thus giving rise to non-conventional signatures in the detector. Dedicated data streams and innovative usage of the CMS detector boost are exploited in this context to significantly boost the sensitivity of such searches at CMS. We present recent results of searches for long-lived particles and other non-conventional signatures obtained using data recorded by the CMS experiment during the completed Run-II and the ongoing Run-III of the LHC.
The MoEDAL-MAPP experiment at the LHC is designed to search for Highly Ionizing Particle (HIPs) such as magnetic monopoles and massive (meta)stable electrically charged particles. The main passive elements of the MoEDAL detector do not require a trigger system, electronic readout, or online computerized DAQ. Also, the detector is immune to standard model backgrounds that can mimic signal events. MoEDAL is sensitive to a number of scenarios where physics from beyond the Standard Model is signified by HIP avatars of new physics. These include magnetic monopoles, dyons, Q-balls, black hole remnants as well as heavy stable singly and multiply charged messengers of new physics, involving non-SUSY and SUSY scenarios.
High-Electric-Charge Objects (HECOs) are featured in numerous theoretical particle physics models extending beyond the Standard Model.
HECOs are actively pursued in contemporary collider experiments like the LHC. In these searches, the determination of mass limits for HECOs has relied on Drell-Yan and Photon-Fusion processes at the tree level thus far. However, these approximations lack reliability due to the breakdown of perturbative QED calculations caused by the large electric charge of HECOs. To address this issue, we introduce a Dyson-Schwinger resummation scheme, enabling computations of HECO-production cross sections. Consequently, we achieve more accurate mass constraints from ATLAS and MoEDAL investigations.
Many theories beyond the Standard Model predict new phenomena giving rise to multijet final states. These jets could originate from the decay of a heavy resonance into SM quarks or gluons, or from more complicated decay chains involving additional resonances that decay e.g. into leptons. Also of interest are resonant and non-resonant hadronic final states with jets originating from a dark sector, giving rise to a diverse phenomenology depending on the interactions between the dark sector and SM particles. This talk presents the latest 13 TeV ATLAS results.
Motivated by the recent release of new results from five different pulsar timing array (PTA) experiments claiming to have found compelling evidence for primordial gravitational waves (GW) at nano-Hz frequencies, we consider the prospects of generating such a signal from inflationary blue-tilted tensor power spectrum in a specific dark matter (DM) scenario dubbed as Miracle-less WIMP. While Miracle-less WIMP, due to insufficient interaction rate with the Standard Model (SM) bath gets thermally overproduced, inflationary blue-tilted gravitational waves (BGW) in compliance with PTA data, conflict cosmological observations if reheat temperature after inflation is sufficiently high. Both these issues are circumvented with late entropy dilution, bringing DM abundance within observational limits and creating a doubly-peaked feature in the BGW spectrum consistent with cosmological observations. The blue-tilted tail of the low-frequency peak can fit NANOGrav 15 yr data, while other parts of the spectrum are within reach of present and future GW experiments.
An ultra slow roll phase during inflation could potentially produce large numbers of primordial black holes which are dark matter candidates. This scenario is considered with transitions from and to slow roll inflation. $\delta N$ analysis shows this model can only possess at most $f_{\text{NL}} = \mathcal{O}{(1)}$ non-Gaussianity. To compute the primordial black hole abundance, we keep the full non-linear relation between curvature perturbation and density contrast. It is found that even with $\mathcal{O}{(1)}$ non-Gaussianity, PBH abundance can be enhanced by orders of magnitudes. As gravitational waves are necessarily generated by black hole formation, the implications for future gravitational waves detectors are discussed.
Metastable cosmic strings are gathering attention as potential progenitors of stochastic gravitatioanl wave background. They result from a two-step symmetry breaking $G\to H\to 1$ with $\pi_1(H)\ne 0$ and $\pi_1(G)=0$, and decay via internal monopole-antimonopole pair creation.
Conventionally, the breaking rate has been estimated by an infinitely thin string approximation, which requires a large hierarchy between the symmetry breaking scales.
We numerically constructed a tunneling path and thus obtained a robust lower limit on the tunneling factor $e^{-S}$ even for mild scale hierarchy. In particular, it is relevant to the cosmic string interpretation of the gravitational wave signals recently reported by pulsar timing array experiments.
Under the assumption that the recent pulsar timing array evidence for a stochastic gravitational wave (GW) background at nanohertz frequencies is generated by metastable cosmic strings, we analyze the potential of present and future GW observatories for probing the change of particle degrees of freedom caused, e.g., by a supersymmetric (SUSY) extension of the Standard Model (SM). We find that signs of the characteristic doubling of degrees of freedom predicted by SUSY could be detected at Einstein Telescope and Cosmic Explorer even if the masses of the SUSY partner particles are as high as about $10^4$ TeV, far above the reach of any currently envisioned particle collider. We also discuss the detection prospects for the case that some entropy production, e.g. from a late decaying modulus field inducing a temporary matter domination phase in the evolution of the universe, somewhat dilutes the GW spectrum, delaying discovery of the stochastic GW background at LIGO-Virgo-KAGRA. In our analysis we focus on SUSY, but any theory beyond the SM predicting a significant increase of particle degrees of freedom could be probed this way.
Several Pulsar Timing Array collaborations have recently found evidence for the presence of a Gravitational Wave Background (GWB) at nHz frequencies. This background could either be sourced by the overlapping GW emission of a population of supermassive black hole binaries or by cosmological sources generating GW in the early Universe. In this talk, I will discuss the prospects of discriminating between these two possibilities by looking for GWB anisotropies.
The trilinear Higgs coupling offers a unique opportunity to probe the structure of the Higgs sector and study the nature of the electroweak phase transition. Recently, it was also shown that confronting the prediction for the trilinear Higgs coupling with the latest experimental bounds opens a powerful new way to probe possible effects of BSM Physics arising from extended Higgs sectors, going beyond existing experimental and theoretical constraints.
In this talk, I will present the new public tool anyH3, which provides predictions for the trilinear Higgs coupling to full one-loop order within arbitrary renormalisable theories. This program allows computing one-, two-, and three-point functions at one loop in an automated way, and furthermore offers a high level of flexibility in the choice of renormalisation conditions. I will review the main elements of the calculation and illustrate applications of anyH3. Finally, I will discuss ongoing extensions of the program.
We present searches from the CMS experiment, performed with data collected during LHC Run 2 at a centre-of-mass energy of 13 TeV, for resonant and nonresonant di-Higgs production. A variety of final states are explored, probing both boosted and resolved topologies.
In the Standard Model, the ground state of the Higgs field is not found at zero but instead corresponds to one of the degenerate solutions minimising the Higgs potential. In turn, this spontaneous electroweak symmetry breaking provides a mechanism for the mass generation of nearly all fundamental particles. The Standard Model makes a definite prediction for the Higgs boson self-coupling and thereby the shape of the Higgs potential. Experimentally, both can be probed through the production of Higgs boson pairs (HH), a rare process that presently receives a lot of attention at the LHC. In this talk, the latest HH searches by the ATLAS experiment are reported, with emphasis on the results obtained with the full LHC Run 2 dataset at 13 TeV. Non-resonant HH search results are interpreted both in terms of sensitivity to the Standard Model and as limits on the Higgs boson self-coupling and the quartic VVHH coupling. The Higgs boson self-coupling can be also constrained by exploiting higher-order electroweak corrections to single Higgs boson production. A combined measurement of both results yields the overall highest precision, and reduces model dependence by allowing for the simultaneous determination of the single Higgs boson couplings. Results for this combined measurement are also presented. Finally, extrapolations of recent HH results towards the High Luminosity LHC upgrade are also discussed.
We analyze the impact of one-loop corrections to triple Higgs bosons on the di-Higgs production cross section at $e^+e^-$ colliders within the two Higgs doublet model (2HDM). In particular, we study the production cross section of two SM-like Higgs bosons together with a $Z$ boson at the ILC. The one-loop triple Higgs couplings are calculated using the one-loop effective potential, and in the case of the SM-like Higgs boson self-coupling $\lambda_{hhh}$, a full one-loop diagrammatic calculation is also considered. We show that one-loop corrections to the Higgs self-coupling can enhance the di-Higgs production cross section by up to a factor of about five with respect to the SM prediction at the ILC, for a center-of-mass energy of 500 GeV and 1 TeV. These large corrections, originating in the one-loop corrections to $\lambda_{hhh}$, arise from the large couplings of the SM-like Higgs boson with other heavy BSM Higgs bosons, while being in agreement with the main theoretical and current experimental constraints. In addition, we discuss the momentum effects from the full one-loop self-coupling prediction, and we show that they are small compared to the results obtained with the effective potential. We also analyze some scenarios where the one-loop corrections to the triple Higgs couplings can affect the resonant production of a heavy neutral Higgs boson, and discuss the implications for the structure of the resonance peak, as well as the accessibility of the BSM triple Higgs coupling at the ILC
The MicroBooNE detector, an 85-tonne active mass liquid argon time projection chamber (LArTPC) at Fermilab, is ideally suited to search for physics beyond the standard model due to its excellent calorimetric, spatial, and energy resolution. We will present several recent results using data recorded with Fermilab’s two neutrino beams: a first search for dark-trident scattering in a neutrino beam, world-leading limits on heavy neutral lepton production, including the first limits in neutrino-neutral pion final states, and new constraints on Higgs portal scalar models. We also use off-beam data to develop tools for a neutron-antineutron oscillation search in preparation for the DUNE experiment. The talk will also discuss the opportunities for future searches using MicroBooNE data.
The Short-Baseline Near Detector (SBND) is one of three Liquid Argon Time Projection Chamber (LArTPC) neutrino detectors positioned along the axis of the Booster Neutrino Beam (BNB) at Fermilab, as part of the Short-Baseline Neutrino (SBN) Program. The detector is currently being commissioned and is expected to take neutrino data this year. SBND is characterized by superb imaging capabilities and will record over a million neutrino interactions per year. Thanks to its unique combination of measurement resolution and statistics, SBND will carry out a rich program of neutrino interaction measurements and novel searches for physics beyond the Standard Model (BSM). It will enable the potential of the overall SBN sterile neutrino program by performing a precise characterization of the unoscillated event rate, and constraining BNB flux and neutrino-argon cross-section systematic uncertainties. In this talk, the physics reach, current status, and future prospects of SBND are discussed.
FASER, the ForwArd Search ExpeRiment, has successfully taken data at the LHC since the start of Run 3 in 2022. From its unique location along the beam collision axis 480 m from the ATLAS IP, FASER has set leading bounds on dark photon parameter space in the thermal target region and has world-leading sensitivity to many other models of long-lived particles. In this talk, we will give a full status update of the FASER experiment and its latest results, with a particular focus on our very first search for axion-like particles and other multi-photon signatures.
NA64 is a fixed target experiment at the CERN SPS searching for dark sectors employing high energy ($\sim$ 100 GeV) electron, positron and muon beams. In this talk, we report its latest results on sub-GeV Dark Matter searches with the 2016-2022 statistics (Phys. Rev. Lett. 131 (2023) no.16, 161801). With the new data, NA64 is starting to probe for the first time the very interesting region of parameter space motivated by benchmark light dark matter models. The experiment can also probe a variety of well-motivated New Physics scenarios that will be briefly covered in this talk such as: ALPs (Phys. Rev. Lett. 125 (2020) no.8, 081801), inelastic DM (Eur. Phys. J. C 83 (2023) no.5, 391), $B-L$ (Phys. Rev. Lett. 129 (2022) no.16, 161801) and $L\mu-L\tau$ $Z’$ boson searches (arXiv:2404.06982). Moreover, we will also present the first results of NA64 running in positron (Phys. Rev. D 109 (2024) no.3, L031103) and muon modes (arXiv:2401.01708).
This talk presents the results from the BaBar experiment on the search for dark matter candidates produced from $B$ mesons decays in $e^+e^−$ annihilations at 10.58 GeV .
We focus on two searches:
The search for exotic B meson decays into a baryon and
a dark sector anti-baryon; $B^+ \rightarrow \psi_D + p$ and $B
\rightarrow \psi_D + \Lambda$. These decays could simultaneously explain the presence of dark matter and the asymmetry between matter-antimatter in the universe. No significant signal is observed, and upper limits on the Branching fractions are placed.
The model independent search for an additional, mostly sterile, Heavy Neutral Lepton (HNL), that mixes with the Standard Model $\tau$ neutrino. The mixing strength is denoted by $|U_{\tau4}|^2$. No significant signal is observed and limits on $|U_{\tau4}|^2$ strength versus the mass hypothesis are presented.
The results are also reinterpreted to provide limits on a super-symmetric model with R-parity violation and a light neutralino.
Since the classic searches for supersymmetry under R-parity conserving scenarios have not given any strong indication for new physics yet, more and more supersymmetry searches are carried out on a wider range of supersymmetric scenarios. This talk focuses on searches looking for signatures of stealth and R-parity-violating supersymmetry. The results are based on proton-proton collisions recorded at sqrt(s) = 13 TeV with the CMS detector.
Various theories beyond the Standard Model predict new, long-lived particles decaying at a significant distance from the collision point. These unique signatures are difficult to reconstruct and face unusual and challenging backgrounds. Signatures from displaced and/or delayed decays anywhere from the inner detector to the muon spectrometer are examples of experimentally demanding signatures. The talk will focus on the most recent results using pp collision data collected by the ATLAS detector.
Supersymmetry (SUSY) provides elegant solutions to several problems in the Standard Model, and searches for SUSY particles are an important component of the LHC physics program. With increasing mass bounds on MSSM scenarios other non-minimal variations of supersymmetry become increasingly interesting. This talk will present the latest results of searches conducted by the ATLAS experiment targeting strong and electroweak production in R-parity-violating models, as well as non-minimal-flavour-violating models.
A wide variety of searches for Supersymmetry have been performed by experiments at the Large Hadron Collider. In this talk, we focus on searches for electroweak production of Supersymmetric particles as well as third generation Supersymmetric particles. Some analyses are optimized for Supersymmetric particles in compressed spectra. The results are obtained from the proton-proton collision data with luminosity up to 138 fb-1 at the center of mass energy of 13 TeV collected during the LHC Run 2.
Supersymmetry (SUSY) models with featuring small mass splittings between one or more particles and the lightest neutralino could solve the hierarchy problem as well as offer a suitable dark matter candidate consistent with the observed thermal-relic dark matter density. However, the detection of SUSY higgsinos at the LHC remains challenging especially if their mass-splitting is O(1 GeV) or lower. Searches are developed using 140 fb^{-1} of proton-proton collision data collected by the ATLAS Detector at a center-of-mass energy \sqrt{s}=13 TeV to overcome the challenge. Novel techniques are developed exploiting machine-learning techniques, low-momentum tracks with large transverse impact parameters, or topologies consistent with VBF production of the supersymmetric particles. Results are interpreted in terms of SUSY simplified models and, for the first time since the LEP era, several gaps in different ranges of mass-splittings are excluded.
There have been numerous recent attempts to elucidate the precise role that the Species Scale plays within quantum gravity, and more generally when trying to characterize the universality class of IR effective field theories (EFT) that descend from a consistent gravitational framework. In this talk we discuss some progress towards the understanding of the Species Scale as the UV cut-off controlling the gravitational EFT expansion, by a careful inspection of several supersymmetric String Theory constructions. The behaviour found is tightly related with the duality web of the theory, and it can even provide interesting insights about the moduli dependence of generalized Wilson coefficients which are not protected by supersymmetry. If time allows, we will also report on an intriguing pattern that such gravitational energy scale seems to fulfil in all known infinite distance/weak coupling corners of the theory.
We study infinite-distance limits in the moduli space of perturbative string vacua. The remarkable interplay of string dualities seems to determine a highly non-trivial dichotomy, summarized by the emergent string conjecture, by which in some duality frame either internal dimensions decompactify or a unique critical string becomes tensionless. Assuming the existence of light states, we investigate whether this pattern persists in potentially non-geometric settings, showing that (a proxy for) the cutoff of the gravitational effective field theory in perturbative type II vacua scales with the spectral gap of the internal conformal field theory in the same manner as in decompactification or emergent string limits, regardless of supersymmetry or whether the internal sector is geometric. As a byproduct, we elucidate the role of the species scale in (de)compactifications and show compatibility between effective field theory and worldsheet approaches in the presence of curvature deformations in geometric settings.
Using flat space string amplitudes and recently computed equilibration rates for a thermal gas of highly excited strings, we argue that a Hagedorn phase could have occured in the early Universe with a bath of open strings dominating the energy density. These strings would predominantly decay in Standard Model fields, providing a successful reheating, and would release a gravitational wave spectrum whose amplitude peaks at a frequency similar to the Cosmic Gravitational Wave Background predicted by the Standard Model, but with a generically larger amplitude.
I will discuss stringy, moduli-driven cosmologies between the end of inflation and the commencement of the Hot Big Bang,a period that can cover half the lifetime of the universe on a logarithmic scale. Compared to the standard cosmology, stringy cosmologies motivate extended kination, tracker and moduli-dominated epochs involving significantly trans-Planckian field excursions. The transPlanckian field evolution may result in radical changes to Standard Model couplings during this history, such as a time-dependent string scale. We will highlight how this can naturally explain a population of cosmic superstrings compatible with existing bounds, and provide predictions for their gravitational wave signatures.
Among various predictions of string compactifications, axions hold a pivotal role, as they provide a unique avenue to tie UV physics to experiments.
Most experimental setups aim to detect a signal using the direct coupling between the axion and the Standard Model. However, string axions do not necessarily need to couple to the Standard Model directly. In this talk I will describe how inflationary models with multiple "spectator" axions coupled to dark gauge sectors via Chern-Simons coupling could source observable gravitational waves.
If string axions coupled to gauge fields undergo slow-roll during inflation, they produce a multi-peak GW signal whose magnitude depends on the details of the compactifications. I will discuss how to embed spectator axions models into type IIB orientifold compactifictions and the restrictions imposed on such models from consistency and control requirements, thereby motivating model that may live in the landscape as opposed to the swampland.
I examine one-loop corrections from small-scale curvature perturbations to the superhorizon-limit ones in single-field inflation models, which have recently caused controversy. I consider the case where the Universe experiences transitions of slow-roll (SR) → intermediate period → SR. The intermediate period can be an ultra-slow-roll period or a resonant amplification period, either of which enhances small-scale curvature perturbations. I assume that the superhorizon curvature perturbations are conserved at least during each of the SR periods. Within this framework, I show that the superhorizon curvature perturbations during the first and the second SR periods coincide at one-loop level in the slow-roll limit.
At high energies, such as during inflation, the quartic coupling of the Standard Model (SM) Higgs potential runs negative, according to current measurements. This can lead the potential into a tachyonic regime, where the square of the mass of the SM Higgs becomes negative. This tachyonic instability can exponentially enhance Higgs particle production via Hubble-induced effects and via the dynamics of the Higgs field itself. Furthermore the enhanced Higgs particle production can draw energy out of the Higgs field and produce stabilizing thermal corrections.
The early produced Higgs particles would then modify the curvature perturbations of the early universe which in turn can cause hot or cold spots on the cosmic microwave background (CMB).
The aim of our work is to look into this enhanced Higgs particle production and calculate the temperature of the CMB hotspots, as well as looking into CMB hotspots from other sources such as primordial black holes.
We propose a new classes of inflation models based on the modular symmetry, where modulus field $\tau$ serves as the inflaton. We make a connection between modular inflation and modular stabilization, and the modulus field rolls towards fixed point after inflation. We find the modular symmetry strongly constraints the possible shape of the potential and find some parameter space where the inflation predictions agree with cosmic microwave background observations. The tensor to scalar ratio is predicted to be smaller than $10^{-6}$ in our models, while the running of spectral index is in order of $10^{-4}$.
In this study, we explore the evolution of a system composed of an unstable scalar field ($\phi$), and radiation in the context of non-standard cosmology where initially the Universe is dominated by the energy density of $\phi$. Later, the unstable $\phi$ with decay width $\Gamma_\phi$ decays into radiation and we focus on two relevant quantities: the maximum radiation temperature $T_{max}$ and the temperature when the universe is dominated by the radiation (reheating temperature) $T_{RH}$. For a given universe's initial Hubble scale ($H_I$) we compare our numerical results from the Boltzmann equations with approximate results in two regimes: $H_I > \Gamma_\phi$ and $H_I < \Gamma_\phi$. Building upon our understanding of the system’s evolution during reheating, we further discuss the viability of Baryogenesis in this scenario.
We make use of Borel resummation to extract the exact time dependence from the divergent series found in the context of stochastic inflation. Correlation functions of self-interacting scalar fields in de Sitter spacetime are known to develop secular IR divergences via loops, and the first terms of the divergent series have been consistently computed both with standard techniques for curved spacetime quantum field theory and within the framework of stochastic inflation. We show that Borel resummation can be used to interpret the divergent series and to correctly infer the time evolution of the correlation functions. In practice, we adopt a method called Borel-Padé resummation where we approximate the Borel transformation by a Padé approximant. We also discuss the singularity structures of Borel transformations and mention possible applications to cosmology.
We explore the real-singlet extension of the Standard Model without a Z2 symmetry (RxSM), as a model to reconstruct the Higgs potental and explain the baryon asymmetry of the Universe. First, we determine regions of parameter space that allow a Strong First-Order Electroweak Phase Transition (SFOEWPT) using the public tools CosmoTransitions and TransitionListener, including also relevant theoretical constraints as well as experimental constraints using HiggsTools. Then, we compute the one-loop corrections to the trilinear Higgs couplings that enter di-Higgs production (hhh and hhH) using the public code anyH3. Finally, we compute the di-Higgs production cross section at the (HL-)LHC in the regions of the RxSM parameter space allowing a SFOEWPT, taking into account the one-loop corrections to the trilinear Higgs couplings. We compare this new result with the results in the SM and in the RxSM at tree level, highlighting the impact of the loop corrections to the trilinear couplings.
The trilinear Higgs coupling is a crucial tool to investigate the structure of the Higgs sector and the nature of the electroweak phase transition, and to probe the parameter space of Beyond-the-Standard-Model (BSM) theories. The vast number of BSM models for which it is relevant to compute the trilinear coupling motivates the automation of its calculation. While calculations are possible at one loop for arbitrary theories using the public code anyH3, at two loops only a handful of model-specific results are available – but in these cases, their inclusion is known to be important.
In this talk, I will present new two-loop results for the trilinear Higgs coupling in generic renormalisable theories. After explaining the setup of our calculation, I will show how we can map our generic expressions onto arbitrary theories. I will review the different checks performed on the new expressions, as well as examples of new results. I will end with some words on possible further steps.
We investigate the reliability of a comparison between the experimental results and the theoretical predictions for the pair production of the 125 GeV Higgs boson at the LHC. Recent experimental results for di-Higgs production provide already sensitivity to triple Higgs couplings (THCs) in models beyond the Standard Model (BSM). In our analysis within the Two Higgs Doublet Model (2HDM) we find that potentially large higher-order corrections to the trilinear couplings and the interference effects arising from additional heavy states have a strong impact on the expected shape of the differential cross section and the value of the total cross section. Both effects have to be taken into account for a correct interpretation of the experimental results. In particular, we demonstrate that neglecting the interference of the contributions of heavy Higgs resonances with non-resonant (background) diagrams, as done by the experimental collaborations, can lead to unreliable exclusion limits.
Understanding the shape of the Higgs potential and the nature of the electroweak phase transition in theories beyond the Standard Model requires experimental information on the trilinear Higgs boson self-coupling $\kappa_3$ and the quartic self-coupling $\kappa_4$. Although triple Higgs production suffers from small cross-section rates, it can establish the first experimental bounds on $\kappa_4$ and provide insights on $\kappa_3$, complementing di-Higgs production analyses. In this work, we consider the $6b$ and $4b2\tau$ decay modes of triple Higgs production at the HL-LHC, utilising efficient Graph Neural Network methodologies to maximise the statistical yield. We demonstrate the potential to impose constraints on both couplings beyond limits from perturbative unitarity. Furthermore, we discuss the prospects from triple Higgs production at upcoming high-energy lepton colliders operating at the TeV scale.
Rare kaon decays are among the most sensitive probes of both heavy and light new physics beyond the Standard Model description thanks to high precision of the Standard Model predictions, availability of very large datasets, and the relatively simple decay topologies. The NA62 experiment at CERN is a multi-purpose high-intensity kaon decay experiment, and carries out a broad rare-decay and hidden-sector physics programme. Recent NA62 results on searches for violation of lepton flavour and lepton number in kaon decays, and searches for production in hidden-sector mediators in kaon decays, are presented. Future prospects of these searches are discussed.
The NA62 experiment at CERN took data in 2016–2018 with the main goal of measuring the $K^+ \rightarrow \pi^+ \nu \bar\nu$ decay.
In this talk we report on the search for visible decays of exotic mediators from data taken in "beam-dump" mode with the NA62 experiment. NA62 can be run as a "beam-dump" experiment by removing the kaon production target and moving the upstream collimators into a ``closed" position. In this configuration 400~GeV protons are dumped on an absorber and New Physics (NP) particles, including dark photons, dark scalars and axion-like particles, may be produced and reach a decay volume beginning 80~m downstream of the absorber. More than $10^{17}$ protons on target have been collected in "beam-dump" mode by NA62 in 2021. Recent results from analysis of this data, with a particular emphasis on Dark Photon and Axion-like particle Models, are presented. We also report new results on the first NA62 search for long-lived NP particles decaying in flight to hadronic final states based on a blind analysis of a sample of $1.4 \times 10^{17}$ protons on dump collected in 2021.
I will discuss our recent paper Phys.Lett.B 843 (2023) 138012 where we propose a minimal model where a dark sector, odd under a Z2 discrete symmetry, is the seed of lepton number violation in the neutrino sector at the loop level, in the context of the linear seesaw mechanism. We study the dark-matter phenomenology of the model, focusing on the case in which the stable particle is the lightest neutral scalar arising from the dark scalar sector. Prospects for testing our framework with the results of current and future lepton flavour violation searches are also discussed.
In this work, we explore a well motivated beyond the Standard Model
scenario, namely, R-parity violating Supersymmetry, in the context of light neutrino
masses and mixing. We assume that the R-parity is only broken by the lepton
number violating bilinear term. We try to fit two non-zero neutrino mass square
differences and three mixing angle values obtained from the global χ 2 analysis of
neutrino oscillation data. We have also taken into account the updated data of the
standard model (SM) Higgs mass and its coupling strengths with other SM particles
from LHC Run-II along with low energy flavor violating constraints like rare b-
hadron decays. We have used a Markov Chain Monte Carlo (MCMC) analysis to
constrain the new physics parameter space. While doing so, we ensure that all the
existing collider constraints are duly taken into account. Through our analysis, we
have derived the most stringent constraints possible to date with existing data on the
9 bilinear R-parity violating parameters along with µ and tan β. We further explore
the possibility of explaining the anomalous muon (g - 2) measurement staying within
the parameter space allowed by neutrino, Higgs and flavor data while satisfying
the collider constraints as well. We find that there still remains a small sub-TeV
parameter space where the required excess can be obtained.
Proton decay, although unobserved so far, is a natural expectation when attempting to explain the baryon asymmetry of the universe. p→K+ν¯ or p→K+χ̃ 01, with χ̃ 01 a light exotic neutral particle, represent possible decay channels achievable in models of physics beyond the Standard Model, such as the MSSM with trilinear R-parity violating terms, or the Standard Model extended by a heavy neutral lepton. Among the decay products of these modes, the neutral fermions would typically appear as missing energy in collider searches. The present study considers how such decay modes could be differentiated in experimental settings, as the exotic χ̃ 01 may further decay if it is not protected by a symmetry (such as R-parity in the MSSM). We assess the detection prospects of the proposed experiments DUNE, JUNO and Hyper-K in this context.
We conduct a model-independent analysis for exotic colored scalars, such as leptoquarks and diquarks, naturally predicted by the E$_{6}$SSM at the LHC with a center-of-mass energy of 13TeV. This analysis focuses on their pair production and subsequent decay into $t \bar{t}\tau \bar{\tau}$ (for leptoquarks) and $t \bar{t} b \bar{b}$ (for diquarks) intermediate states. In the case of leptoquarks, we demonstrate that with the assumption of utilizing the entire luminosity of Run 2, a fully hadronic signal originating from this intermediate state can exhibit greater sensitivity compared to the established searches that rely on leptons in the final state. Furthermore, we illustrate that diquarks can be reconstructed by applying on-shell conditions when the $t \bar{t}$ pair decays semi-leptonically.
Even though the light Higgs bosons receive a strong negative impact from the experimental analyses, the extensions of MSSM can consistently place such light scalars in the low scale spectrum. These light scalar can be tested in near future analyses through their decays into SM gauge bosons and/or fermions. Even though the current results rather provide strong exclusions, these scalars can indirectly mimic through their productions associated with some SM particles. In our work, the SUSY GUT models will be discussed which extend the MSSM gauge group by a U(1) symmetry under which the MSSM fields are nontrivially charged. After summarizing the impact from the current experiments, it will be discussed some possible detection/exclusion processes through their production associated with a photon.
Euclidean wormholes provide concrete examples of non-perturbative gravitational effects leading to a violation of global symmetries. In this talk I will present and analyze a new class of wormhole solutions universally realised in a large set of four-dimensional $\mathcal{N}=1$ axiverse scenarios, and study their low-energy physical implications.
I will present some multi-parametric families of non-supersymmetric EAdS4 flows as well as asymptotically EAdS4 solitons and wormholes, which are constructed within the four-dimensional SO(8) gauged supergravity that describes the compactification of M-theory on S7.
I will also comment on the computation of the on-shell action and gravitational free energy for the regular solutions, the latter being zero for the wormholes.
Lastly, I will discuss the presence of special loci in parameter space yielding solutions with enhanced (super)symmetry, and describe the uplift of these examples to Euclidean solutions of eleven-dimensional supergravity.
In six dimensions, there is an exotic N = (4, 0) supermultiplet that contains only fields of spin ≤ 2, but no graviton, and that on a circle reduces to 5D N = 4 supergravity. It has been proposed that, if suitable interactions exist, the (4, 0) theory might provide a consistent alternative UV completion for N = 4 5D supergravity, realizing a supersymmetric version of asymptotic safety. In this note we argue that any Lorentz-invariant (4, 0) theory (interacting or not) carries an exact global symmetry when compactified on S^1, and is therefore incompatible with the Swampland no global symmetries conjecture. Another example of
exotic supergravity, the 6D (3, 1) theory, does not have this problem. We study the general case and find that the only exotic spin-2 field that reduces to Einsteinian gravity and has no global symmetries when compactified on a high-dimensional torus is that of the (3, 1) theory.
All other possibilities either yield several gravitons or have global symmetries.
The 11-dimensional supergravity is famously the unique maximal supergravity in the maximal possible number of spacetime dimensions. I will discuss the construction of a novel non-relativistic supergravity in 11-d, by taking a limit of the 11-dimensional supergravity. This limit breaks the local Lorentz symmetry from SO(1,10) to SO(1,2) x SO(8) and so is linked to the appearance of membranes in 11 dimensions. As well as providing access to a non-relativistic corner of quantum gravity, this limit is U-dual to the Matrix Theory description of M-theory. Based on work in progress with E. Bergshoeff, J. Lahnsteiner and J. Rosseel.
Peccei-Quinn (PQ) mechanism is a prominent solution to the strong CP problem. In this mechanism, spontaneous breaking of an anomalous global symmetry (PQ symmetry) generates a pseudo-Nambu-Goldstone boson called axion, which is also a dark matter candidate. From observational reasons, the energy scale of the symmetry breaking is constrained to be greater than about 10^9 GeV, or even more to explain all the dark matter. With this constraint, a theoretical problem for PQ mechanism arises. The problem is that Planck-suppressed operators which explicitly violate PQ symmetry can easily generate non-zero effective theta angle exceeding the experimental limit. To avoid this problem, several models with higher-energy dynamics are proposed. Among them are composite axion models, in which PQ symmetry is spontaneously broken by strong dynamics in high-energy, resulting in the axion emerging as a composite state. In models with such high-energy dynamics, calculation of the axion mass only in QCD is not necessarily sufficient, and small instantons in higher-energy dynamics, absent in QCD, may enhance the axion mass. In my presentation, I will explain that small instantons do not enhance the axion mass in some specific composite axion models, although the enhancement seems possible at first sight.
We study the dynamics of axions at first-order phase transitions in non-Abelian gauge theories. When the duration of the phase transition is short compared to the timescale of the axion oscillations, the axion dynamics is similar to the trapped misalignment mechanism. On the other hand, if this is not the case, the axions are initially expelled from the inside of the bubbles, generating axion waves on the outside. Analogous to the Fermi acceleration, these axions gain energy by repeatedly scattering off the bubble walls. Once they acquire enough energy, they can enter the bubbles. If the axion oscillations are relevant only inside the bubbles during the phase transition, the axion abundance is significantly enhanced compared to models where the axion mass is either constant or varies continuously as a function of temperature. The increase in axion abundance depends on the axion mass, the duration of the phase transition, and the bubble wall velocity. This mechanism results in a spatially inhomogeneous distribution of axions, which could lead to the formation of axion miniclusters. It has potential implications for the formation of oscillons/I-balls, axion warm dark matter, cosmic birefringence, and the production of dark photons.
We present a new mechanism to generate a coherently oscillating dark vector field from axion-SU(2) gauge field dynamics during inflation. The SU(2) gauge field acquires a nonzero background sourced by an axion during inflation, and it acquires a mass through spontaneous symmetry breaking after inflation. We find that the coherent oscillation of the dark vector field can account for dark matter in the mass range of $10^{−13}$ – 1 eV in a minimal setup. One of the dark vector fields can be identified as the dark photon, in which case this mechanism evades the notorious constraints for isocurvature perturbation, statistical anisotropy, and the absence of ghosts that exist in the usual misalignment production scenarios. Phenomenological implications are also discussed.
After several decades of intense experimental effort to find them, SUSY Neutralinos remain elusive and much of the attention has shifted to alternative Dark Matter (DM) candidates in the past few years. There still remain, nevertheless, large unexplored parameter regions inaccessible by direct (collider) detection experiments.
Indirect detection using current and next-generation air Cherenkov telescopes, on the other hand, offers a promising avenue to test otherwise undetectable Neutralino DM hypotheses. These instruments are e.g. capable to search for above-TeV scale neutralinos, which are ubiquitous in e.g. (mini)split SUSY scenarios.
The several-TeV (neutralino mass) to a few hundred GeV (electroweak symmetry breaking scale) hierarchy that is present in these models induces non-negligible quantum effects that are not accounted-for in standard (automated) computations. The most prominent one is the so-called Sommerfeld effect, which can give rise to huge enhancements of several orders of magnitude to the predicted gamma-ray spectra.
This effect features sizeable (in some cases dominant) contributions of virtual chargino-antichargino pairs to the annihilation cross sections that had not been computed before. By including these and the corresponding Sommerfeld factors in the context of the Minimal Supersymmetric Standard Model, one can obtain the to-date most robust prediction for the gamma-ray spectra associated to Neutralino annihilation.
In this talk I will mostly focus on discussing the key aspects of these challenging computations and their numerical impact.
These results are accessible at this https URL
The nature of dark matter (DM) and its interaction with the Standard Model (SM) is one of the biggest open questions in physics nowadays. The vast majority of theoretically-motivated Ultralight-DM (ULDM) models predict that ULDM couples dominantly to the SM strong/nuclear sector. This coupling leads to oscillations of nuclear parameters that are detectable by comparing clocks with different sensitivities to these nature's constants. Vibrational transitions of molecular clocks are more sensitive to a change in the nuclear parameters than the electronic transitions of atomic clocks. Here, we propose the iodine molecular ion, I$_2^+$, as a sensitive detector for such a class of ULDM models. The iodine's dense spectrum allows us to match its transition frequency to that of an optical atomic clock (Ca$^+$) and perform correlation spectroscopy between the two clock species. With this technique, we project a few-orders-of-magnitude improvement over the most sensitive clock comparisons performed to date. We also briefly consider the robustness of the corresponding "Earth-bound" under modifications of the $Z_N$-QCD axion model.
Constraints on dark sector particles decaying into neutrinos typically focus on their impact on the effective number of relativistic species, $N_{eff}$, in the early Universe. However, for heavy relics with longer lifetimes, constraints mainly arise from the photo-disintegration of primordial abundances. The high-energy neutrinos injected by the decay can interact with both the thermal neutrinos and other high-energy neutrinos. Among these interactions, annihilations into electromagnetic particles will induce an electromagnetic cascade that affects the abundances of the already formed light elements via photo-disintegration. In this work, we present constraints on these dark sector particles. Specifically, we implement a Monte Carlo code to simulate the electromagnetic cascade, instead of solving the full set of Boltzmann equations. We find improved bounds on the particle's lifetime, abundance, and mass.
We derive the complete set of one-loop renormalization-group equations (RGEs) for the operators up to dimension-six (dim-6) in the seesaw effective field theories (SEFTs). Two kinds of contributions to those RGEs are identified, one from double insertions of the dimension-five (dim-5) Weinberg operator and the other from single insertions of the tree-level dim-6 operators in the SEFTs. A number of new results are presented. First, as the dim-5 Weinberg operator is unique in the standard model effective field theory (SMEFT), its contributions to the RGEs for the SEFTs are equally applicable to the SMEFT. We find the full contributions from the Weinberg operator to one-loop RGEs in the SMEFT, correcting the results existing in previous works, and confirm that those from dim-6 operators are consistent with the results in the literature. Second, in the type-I SEFT, we give the explicit expressions of the RGEs of all the physical parameters involved in the charged- and neutralcurrent interactions of leptons. Third, the RGEs are numerically solved to illustrate the running behaviors of the non-unitary parameters, mixing angles and CP-violating phases in the non-unitary leptonic flavor mixing matrix. Together with the one-loop matching results of the dim-5 and dim-6 operators and their Wilson coefficients, the present work has established a self-consistent framework up to dim-6 to investigate low-energy phenomena of three types of seesaw models at the one-loop level.
After a brief introduction to neutrino electromagnetic properties, I will focus on the correlation between neutrino magnetic moment and neutrino mass mechanism. Then, I will discuss that the models that induce large neutrino magnetic moments while maintaining their small masses naturally also predict observable shifts in the charged lepton anomalous magnetic moment by showing that the measurement of muon g−2 by the Fermilab experiment can be an in-direct and novel test of the neutrino magnetic-moment hypothesis, which can be as sensitive as other ongoing-neutrino/dark matter experiments. The promising new possibilities for probing neutrino electromagnetic properties in future experiments from terrestrial experiments and astrophysical considerations will also be discussed. This talk will be based on results obtained in hep-ph 2303.13572, 2203.01950, 2104.03291, and 2007.04291.
Extensions of the Standard Model (SM) scalar sector featured in radiative neutrino mass models possess the ingredients for exotic thermal histories and rich possibilities for beyond SM physics. In this talk, we will explore the possibility of early Universe non-restoration of the $U(1)_Y$ gauge symmetry in the Zee-Babu neutrino mass generation model and the ways in which this phenomenology can be harnessed in mechanisms of baryo- and leptogenesis. We will find that subtleties in the treatment of finite-temperature perturbation theory play a decisive role in mapping out the parameter space of phenomenological interest. The highlight of the talk will be a novel baryon asymmetry generating mechanism which crucially relies on the high-temperature $U(1)_Y$ breaking phase and the exotic phenomenology of charge-breaking SM lepton masses therein.
The unique dimension-$5$ effective operator, $LLHH$, known as the Weinberg operator, generates tiny Majorana masses for neutrinos after electroweak spontaneous symmetry breaking. If there are new scalar multiplets that take vacuum expectation values (VEVs), they should not be far from the electroweak scale. Consequently, they may generate new dimension-$5$ Weinberg-like operators which in turn also contribute to Majorana neutrino masses. In this study, we consider scenarios with one or two new scalars up to quintuplet $SU(2)$ representations. We analyse the scalar potentials, studying whether the new VEVs can be induced and therefore are naturally suppressed, as well as the potential existence of pseudo-Nambu-Goldstone bosons. Additionally, we also obtain general limits on the new scalar multiplets from direct searches at colliders, loop corrections to electroweak precision tests and the $W$-boson mass.
Domain walls are a type of topological defects that can arise in the
early universe after the spontaneous breaking of a discrete symmetry. This occurs in several beyond Standard Model theories with an
extended Higgs sector such as the Next-to-Two-Higgs-Doublet model
(N2HDM). In this talk I will discuss the domain wall solution related
to the singlet scalar of the N2HDM as well as demonstrate the possibility of restoring the electroweak symmetry in the vicinity of the
domain wall. Such symmetry restoration can have profound implications on the early universe cosmology as the sphaleron rate inside the
domain wall would, in principle, be unsuppressed compared with the
rate outside the wall.
We present a detailed study of the precision calculations of higher-order contributions to effective potential with the application of three-dimensional effective field theories (3D EFTs). Our work focuses on the thermodynamic quantification and description of electroweak phase transitions in the early Universe for the complex singlet extended Standard Model (cxSM). In particular, we address the issue of gauge and scale dependences associated with the effective potential, which can lead to ambiguities when calculating thermodynamical quantities from the effective potential. To overcome this issue, we employ the high temperature 3D EFT framework, which provides a robust approach for consistently taking into account the relevant contributions in physical predictions. In addition, we study the ambiguities in commonly used renormalization schemes of the effective potential. The phenomenological implications of our results are discussed
Computing the decay rate of a meta-stable state is a well-known problem with relevance in various areas of physics. The decay rate is dominated by an exponential factor called the bounce action. Determining the bounce action for a given potential and meta-stable vacuum involves solving a set of partial differential equations with intricate boundary conditions. There are several dedicated solvers available for this problem, however finding bounce actions in potentials of many variables still remains a challenge. We use a neural network to solve the partial differential equation for finding the tunneling path. We apply this approach to analyze vacuum stability in both the Minimal Supersymmetric extension of the Standard Model (MSSM) and the Next-to-MSSM (NMSSM), where we determine bounce actions for the tree-level potential including all Higgs fields and 3rd generation sfermions. We compare the resulting constraints on the parameter space of the (N)MSSM to the ones from LHC Higgs measurements.
The evolution of the early Universe around the electroweak epoch is an ideal testbed for physics beyond the Standard Model and in particular extended scalar sectors. The Universe may have experienced a sequence of phases of exotic nature, one of these being an intermediate phase where the electromagnetic charge is not conserved.
In my talk, intermediate $U(1)_\mathrm{em}$ charge-breaking (CB) phases in the CP-conserving 2-Higgs Doublet Model will be investigated. While previously studied only in the approximation of high temperatures, the possibility for their existence in the one-loop effective potential including thermal corrections is confirmed. I will discuss the relation of CB phases with the (non-)restoration of the electroweak $SU(2)\times U(1)$ symmetry at high temperatures, and the consistency with current collider data. For certain selected benchmark scenarios, the features of a CB phase in the evolution of the vacuum will be examined, such as the occurrence of a first-order phase transition to the CB phase from the neutral one.
Supersymmetric models with low electroweak finetuning are expected to be more prevalent on the string landscape than finetuned models. We assume a fertile patch of landscape vacua containing the minimal supersymmetric standard model (MSSM) as low energy/weak scale effective field theory (LE-EFT). Then, a statistical pull by the landscape to large soft terms is balanced by the requirement of a derived value of the weak scale which is not too far from its measured value in our universe. Such models are characterized by light higgsinos in the few hundred GeV range whilst top squarks are in the 1-2.5 TeV range with large trilinear soft terms which helps to push $m_h\sim 125$ GeV. Other sparticles are generally beyond current LHC reach and the $BR(b\to s\gamma )$ branching fraction is nearly equal to its SM value. The light top-squarks decay comparably via $\tilde{t}_1\to b\tilde\chi_1^+$ and $\tilde t_1\to t\tilde\chi_{1,2}^0$ yielding mixed final states of $b\bar{b}+\not\!\!\!{E_T}$, $t\bar{b}/\ \bar{t}b +\not\!\!\!{E_T}$ and $t\bar{t}+\not\!\!\!{E_T}$. We evaluate prospects for top squark discovery at high-luminosity (HL) LHC for the well-motivated case of natural SUSY from the landscape. We find for HL-LHC a $5\sigma$ reach out to $m_{\tilde t_1}\sim 1.65$ TeV and a 95% CL exclusion reach to $m_{\tilde t_1}\sim 1.95$ TeV. These reaches cover most (but not all) of the allowed stringy natural parameter space!
We present the production rates of colored states at a multi-TeV muon collider. We include the cases of a color-triplet scalar, color-triplet fermion, color-octet scalar, and color-octet fermion.
Recently, a novel collider, called $\mu$TRISTAN, has been proposed, offering the capability to achieve high-energy collisions of anti-muons.
This high-energy collider presents an exceptional opportunity for the discovery of electroweak-interacting massive particles (EWIMPs), which are predicted by various new physics models.
In a lepton collider like $\mu$TRISTAN, the potential for discovering EWIMPs extends beyond their direct production. Quantum corrections arising from EWIMP loops can significantly enhance our prospects for discovery by precise measurement of Standard Model processes.
This study focuses on the indirect detection method within the $\mu$TRISTAN experiment, with a specific emphasis on TeV-scale EWIMP dark matter scenarios that yield the correct thermal relic density. At collision energies for $ \sqrt{s} = O(1-10)$ TeV, these EWIMPs introduce noticeable effects, typically in the range of $O(0.1-1)$%.
Our findings indicate that at $\sqrt{s} = 2\, (10)$ TeV, with an integrated luminosity of 10 ab$^{-1}$, the $\mu$TRISTAN can detect Higgsino at a mass of 1.3 (2.5) TeV and Wino at a mass of 1.9 (3.8) TeV, assuming an optimistic level of systematic uncertainty in the observation of the Standard Model processes.
The three ten dimensional, non-supersymmetric and non-tachyonic string theories are a great arena for understanding quantum gravity away from the supersymmetric lamppost. However, their full consistency remains unestablished; despite the cancellation of local anomalies, the presence of potential global anomalies poses a threat of becoming fatal pathologies.
After briefly introducing these theories, I will discuss the cancellation of their global gauge/gravitational anomalies through the computation of bordism groups. This serves as a great consistency check for these theories and allows us to shine light on this non-supersymmetric corner of string theory.
Based on arXiv:2310.06895.
We investigate the four-dimensional WZW terms within the framework of Sp QCD using invertible field theory through bordism theory. We present a novel approach aimed at circumventing both perturbative and non-perturbative gauge anomalies on spacetime manifolds endowed with spin structures. We study both ungauged and gauged WZW terms including the problems of the topological consistency of gauged WZW terms.
The cobordism conjecture implies that consistent theories of Quantum Gravity must admit the introduction of boundaries. We study the dynamical realization of the cobordism conjecture in type IIB in $AdS_5\times S^5$, using the existing gravity duals of 4d $\mathcal{N} = 4$ SYM with Gaiotto-Witten superconformal boundary conditions (near-horizon limits of D3-branes ending on NS5- and D5-branes). We show that these configurations are, from the 5d perspective, dynamical cobordism solutions which start from an asymptotic $AdS_5$ vacuum and evolve until they hit an end of the world (ETW) brane with $AdS_4$ worldvolume. We extend the picture to $AdS_5$ theories with less (super)symmetry, via orbifolds and S-folds, leading to dynamical cobordisms for gravity duals of 4d theories with $N = 2$ and $N = 3$ supersymmetry.
In this talk we will present an innovative and alternative way to realise a four-dimensional accelerated expanding cosmology from string theory. This construction is known as the Dark Bubble model and it suggests that an induced four-dimensional universe rides on the boundary (i.e. an expanding $D_{3}$-brane) of a five-dimensional true Anti-de Sitter vacuum that has nucleated within a false AdS vacuum.
The stringy top-down construction of this model comes equipped with a precise and novel scale of hierarchies. This new hierarchy suggests new phenomenology just around the corner of our current observations. Furthermore, we will discuss the unexplored potential of the Dark Bubble model to accommodate higher-dimensional interpretations of four-dimensional fundamental forces induced on the expanding $D_{3}$-brane.
The tadpole conjecture constrains the number of moduli that can be stabilized with fluxes in F-theory and type IIB flux compactifications. In this talk, I will discuss ongoing work that tests this assertion in non-geometric type IIB flux compactifications with no K\"ahler moduli. In particular, I will restrict to supersymmetric Minkowski vacua in orbifolds of the 1^9 and 2^6 Gepner models. Generically these Minkowski critical points have many massless directions. In principle, we are able to expand the flux superpotential around these Minkowski critical points upto arbitrary order. This allows us to ask if these massless directions are truly flat or if they get stabilized by some higher-than-quadratic order term in the superpotential.
Axion-like particles (ALPs) are expected to arise in a wide variety of models, whenever a global symmetry is spontaneously broken. Although they can produce a rich phenomenology, they typically need to be supplemented by extra new physics in order to explain neutrino masses. In this talk, we will discuss the interplay of axion-like particles and heavy neutral leptons in a collider setting, considering various ALP couplings and type-I see-saw realisations. We will show that the unique processes that arise in the presence of both particles can lead to strong joint constraints at the LHC and a future muon collider.
The MoEDAL-MAPP experiment is currently installing the MAPP-1 (MoEDAL Apparatus for Penetrating Particles, Phase-1) in the UA83 tunnel on the LHC ring to search for evidence of Weakly Ionizing Particles (WIPs) , such as millicharged particles. MAPP-2 will be deployed in during the LHC’s next long shutdown to take data along with MoEDAL and MAPP-1 at the High Luminosity LHC. MAPP-2 is designed to search for very Long-Lived neutral Particles (LLPs) that decay to charged and photonic states from, for example, dark sector, heavy neutrino, mirror-world and supersymmetric scenarios. We will briefly describe the MAPP-1 and MAPP-2 detectors and illustrate their sensitivity by considering several new physics benchmark scenarios.
The proposed LUXE experiment (LASER Und XFEL Experiment) at DESY, Hamburg, using the electron beam from the European XFEL, aims to probe QED in the non-perturbative regime created in collisions between high-intensity laser pulses and high-energy electron or photon beams. This setup also provides a unique opportunity to probe physics beyond the standard model. In this talk we show that by leveraging the large photon flux generated at LUXE, one can probe axion-like-particles (ALPs) up to a mass of 350 MeV and with photon coupling of 3×10−6 GeV−1. This reach is comparable to the background-free projection from NA62. In addition, we will discuss the ongoing optimisation of the experimental setup for the ALP search.
Cosmological first order phase transitions are typically associated with physics beyond the Standard Model, and thus of great theoretical and observational interest. Models of phase transitions where the energy is mostly converted to dark radiation can be constrained through limits on the dark radiation energy density (parameterized by $\Delta N_{\rm eff}$). However, the current constraint ($\Delta N_{\rm eff} < 0.3$) assumes the perturbations are adiabatic. We point out that a broad class of non-thermal first order phase transitions that start during inflation but do not complete until after reheating leave a distinct imprint in the scalar field from bubble nucleation. Dark radiation inherits the perturbation from the scalar field when the phase transition completes, leading to large-scale isocurvature that would be observable in the CMB. We perform a detailed calculation of the isocurvature power spectrum and derive constraints on $\Delta N_{\rm eff}$ based on CMB+BAO data. For a reheating temperature of $T_{\rm rh}$ and a nucleation temperature $T_*$, the constraint is approximately $\Delta N_{\rm eff}\lesssim 10^{-5} (T_*/T_{\rm rh})^{-4}$, which can be much stronger than the adiabatic result. We also point out that since perturbations of dark radiation have a non-Gaussian origin, searches for non-Gaussianity in the CMB could place a stringent bound on $\Delta N_{\rm eff}$ as well.
A new theory is presented to estimate the mass, size, lifetime, and other properties of cold dark matter particles (CDM) within the ΛCDM cosmology. Using Illustris simulations, we demonstrate the existence of mass and energy cascade that facilitates the formation of hierarchical structures. A scale-independent rate of cascade $\varepsilon_u\approx 10^{-7}m^2/s^3$ can be identified. The energy cascade leads to universal scaling laws on relevant scales r, i.e. a two-thirds law for kinetic energy ($v_r^2\propto \varepsilon_u^{2/3} r^{2/3}$) and a four-thirds law for DM halo density ($\rho_r\propto \varepsilon_u^{2/3}G^{-1}r^{-4/3}$), where G is the gravitational constant. For cold and collisionless dark matter that interacts via gravity only, these scaling laws can be extended down to the smallest scale, that is, a free streaming scale. For standard WIMPs, that scale is about Earth's mass. For superheavy dark matter particles of mass $10^{12}$GeV, the free streaming mass can be comparable to the particle mass such that quantum effects can be important on that scale. Combined with the uncertainty principle and virial theorem, three constants ($\varepsilon_u$, $\hbar$, and G) dominate the physics on that scale, so that the properties of CDM can be estimated. We estimate a mass $m_X=(\varepsilon_u\hbar^5G^{-4})^{1/9}=10^{12}$GeV, a size $l_X=(\varepsilon_u^{-1}\hbar G)^{1/3}=10^{-13}$m, and a lifetime $\tau_X=c^2/\varepsilon_u=10^{16}$ years for CDM particles. Here, $\hbar$ is the Planck constant and c is the speed of light. The typical energy on that scale $E_X=(\varepsilon_u^5\hbar^7G^{-2})^{1/9}=10^{-9}$eV suggests a “dark radiation” field to provide a viable mechanism for the energy dissipation during gravitational collapsing of CDM. If existing, the “dark radiation" should be produced around $t_X=(\varepsilon_u^{-5}\hbar^2G^2)^{1/9}=10^{-6}$s (quark epoch) with mass of $10^{-9}$eV, a GUT scale decay constant $10^{16}$GeV, or an effective axion-photon coupling $10^{-18}$GeV$^{-1}$, such that the axion particle can be a very promising candidate for “dark radiation". The energy density of “dark radiation” is estimated to be about 1% of the cosmic microwave background (CMB). This work suggests a heavy dark matter scenario created during inflationary epoch along with a light axion-like dark radiation field. Potential extension to self-interacting dark matter is also presented. More details can be found at arXiv:2202.07240.
The main limitation for pre-inflationary breaking of Peccei-Quinn (PQ) symmetry is the upper bound on the Hubble rate during inflation from axion isocurvature fluctuations. This leads to a tension between high scale inflation and QCD axions with Grand Unified Theory (GUT) scale decay constants, which reduces the potential for a detection of tensor modes at next generation CMB experiments. We propose a mechanism that excplicitly breaks PQ symmetry via non-minimal coupling to gravity, that lifts the axion mass above the Hubble scale during inflation and has negligible impact on today's axion potential. The initially heavy axion gets trapped at an intermediate minimum during inflation given by the phase of the non-minimal coupling, before it moves to its true CP-conserving minimum after inflation. During this stage it undergoes coherent oscillations around an adiabatically decreasing minimum, which slightly dilutes the axion energy density, while still being able to explain the observed dark matter relic abundance. This scenario can be tested by the combination of next generation CMB surveys like CMB-S4 and LiteBIRD with haloscopes such as ABRACADABRA or CASPEr-Electric.
When the inflaton is coupled to the gluon Chern-Simons term for successful reheating, mixing between the inflaton and the QCD axion is generally expected given the solution of the strong CP problem by the QCD axion. This is particularly natural if the inflaton is a different, heavier axion. We propose a scenario in which the QCD axion plays the role of the inflaton by mixing with heavy axions. In particular, if the energy scale of inflation is lower than the QCD scale, a hybrid inflation is realized where the QCD axion plays the role of the inflaton in early stages. We perform detailed numerical calculations to take account of the mixing effects. Interestingly, the initial misalignment angle of the QCD axion, which is usually a free parameter, is determined by the inflaton dynamics. It is found to be close to \pi in simple models. This is the realization of the pi-shift inflation proposed in previous literature, and it shows that QCD axion dark matter and inflation can be closely related. The heavy axion may be probed by future accelerator experiments.
Very detailed measurements of Higgs boson coupling and kinematical properties can be performed using the data collected with the ATLAS experiment, exploiting a variety of final states and production modes, and probing different regions of the phase space with increasing precision. These measurements can then be combined to exploit the specific strength of each channel, thus providing the most stringent global measurement of the Higgs properties. This talk presents the latest combination of Higgs boson measurements by the ATLAS experiment, with results presented in terms of production modes, branching fractions, Simplified Template Cross Sections and coupling modifiers. These combined measurements are interpreted in various ways: specific scenarios of physics beyond the Standard Model are tested, as well as a generic extension in the framework of the Standard Model Effective Field Theory. The results are based on pp collision data collected at 13 during Run 2 of the LHC.
In this work we explore the phenomenological implications at future e+e− colliders of assuming anomalous couplings of the Higgs boson to gauge bosons HVV and HHVV (V = W, Z) given by the κ-modifiers with respect to the Standard Model couplings, κV and κ2V, respectively. For this study we use the Higgs Effective Field Theory (HEFT) where these two κ parameters are identified with the two most relevant effective couplings at leading order, concretely a = κV and b = κ2V . Our focus is put on these two couplings and their potential correlations which we believe carry interesting information on the underlying ultraviolet theory. The particular studied process is e+e− → HHν¯ν, where the vector boson scattering subprocess WW → HH plays a central role, specially at the largest planned energy colliders. Our detailed study of this process as a function of the energy and the angular variables indicates that the produced Higgs bosons in the BSM scenarios will have in general a high transversality as compared to the SM case if κV^2 is different from κ2V. In order to enhance the sensitivity to these HEFT parameters κV and κ2V and their potential correlations we propose here some selected differential cross sections for the e+e− → HHν¯ν process where different kinematic properties of the BSM case with respect to the SM are manifested. Finally, we will focus on the dominant Higgs decays to b¯b pairs leading to final events with 4 b-jets and missing transverse energy
from the undetected neutrinos and will provide the expected accessibility to the (κV , κ2V) effective couplings and their potential correlations. In our study we will consider the three projected energies for e+e− colliders of 500 GeV, 1000 GeV and 3000 GeV.
Various extensions of the Standard Model predict the existence of additional Higgs bosons. If these additional Higgs bosons are sufficiently heavy, an important search channel is the di-top final state. In this channel, interference effects between the signal and the corresponding QCD background process are important. If more than one heavy scalar is present, besides the signal-background interference effects associated with each Higgs boson also important signal-signal interference effects are possible. We perform a model-independent analysis of various interference contributions within a simplified model framework considering two heavy scalars that can mix with each other, taking into account large resonance-type effects arising from loop-level mixing between the scalars. The interference effects are studied with Monte Carlo simulations for the di-top production at the LHC. We demonstrate that signatures can emerge from these searches that may be unexpected or difficult to interpret.
I will discuss our recent paper Phys.Rev.Lett. 132 (2024) 5, 051801, where we propose a generalized KSVZ-type axion framework in which coloured fermions and scalars act as two-loop Majorana neutrino-mass mediators. The global Peccei-Quinn symmetry under which exotic fermions are charged solves the strong CP problem. Within our general proposal, various setups can be distinguished by probing the axion-to-photon coupling at helioscopes and haloscopes. We also comment on axion dark-matter production in the early Universe.
Scotogenic models are phenomenologically very interesting as they generate neutrino masses through the mediation of $Z_2$-odd particles (which can serve as dark matter candidate) in loops. We have analysed singlet-triplet scotogenic model in the connection of direct detection possibility of the fermionic dark matter. This model appears compelling as it shows some SUSY-like behaviour without the introduction of SUSY. We consider several theoretical and experimental bounds on this model and study the effects of co-annihilation too. The mass of $Z_2$-even scalar (neutral and charged) plays an important role in the estimation of the dark matter relic density. We perform the analysis considering very heavy $Z_2$-even scalars relative to the Standard Model Higgs. Fermionic dark matter of mass below 60 GeV seems disfavoured in this model due to incompatibility of neutrino oscillation data with collider studies and bounds from charged lepton flavor violation. Fermion-fermion and fermion-scalar co-annihilations play complementary roles in terms of the direct detection possibility in different regions of the parameter-space.
Sterile neutrinos are well-motivated and simple dark matter (DM) candidates. However, sterile neutrino DM produced through oscillations by the Dodelson-Widrow mechanism is excluded by current X-ray observations and bounds from structure formation. One minimal extension, that preserves the attractive features of this scenario, is self-interactions among sterile neutrinos. In this work, we analyze how sterile neutrino self-interactions mediated by a scalar affect the production of keV sterile neutrinos for a wide range of mediator masses. We find four distinct regimes of production characterized by different phenomena, including partial thermalization for low and intermediate masses and resonant production for heavier mediators. We show that significant new regions of parameter space become available which provide a target for future observations.