With the measurement of double Higgs production within reach, it is justified to expand our interest to more exotic processes, such as three Higgs boson production. This rare process is crucial for advancing our understanding of the Higgs boson, its interactions (including self-coupling), the Higgs potential, and the mechanism of electroweak symmetry breaking (EWSB). This talk explores the...
Exploring the Higgs sector via multi-Higgs production searches is a main goal for run-3 and high-lumi LHC. Can these searches inform us about the electroweak phase transition and matter-antimatter asymmetry?
We address this question in the context of the TRSM (Two-Real-Singlet Model), which has known benchmark points enhancing multi-Higgs production.
We update the triple-Higgs production...
The most general CP-violating two-Higgs-doublet model (2HDM) in the Yukawa alignment limit can produce significant di-photon branching ratios for the neutral scalars of the model. In the Higgs basis, where the two scalar doublets are identified as $H_1$ and $H_2$, the lagrangian term $Z_7 H_1^\dagger H_2 H_2^\dagger H_2 + {\rm h.c.}$ enters the branching ratios to di-photon of the new physics...
The precise determination of the Higgs boson self-couplings is essential for understanding the mechanism behind electroweak symmetry breaking. However, due to the limited number of Higgs boson pair events at the LHC, only loose constraints have been established so far. Current constraints are based on the assumption that the cross section is a quadratic function of the trilinear Higgs...
We present a new simulation for Higgs boson production in association with bottom quarks ($bbH$) at next-to-leading order (NLO) matched to parton showers. The contributions proportional to the bottom-quark Yukawa coupling and top-quark Yukawa coupling (from gluon fusion) are both taken into account in a scheme with massive bottom quarks. The $bbH$ process constitutes a crucial background to...
A calibratable experimental strategy is proposed to enhance the $HH(4b)$ search sensitivity via full-particle classification. Inspired by the competitive performance from the boosted-topology $HH$ analysis, which uses state-of-the-art jet neural networks to analyze $o(100)$ particles within large-$R$ jets, this approach aims to extend its strong signal-to-background discrimination power beyond...
The Circular Electron Positron Collider (CEPC) was proposed shortly after the discovery of the Higgs boson at the LHC, as a Higgs factory, with the possibility of being upgraded to a proton-proton collider in the future. The CEPC Study Group has been continuously working on the design of the accelerator, the R&D of critical technologies and components for both the collider and the...
One of the LHC's priorities, following the discovery of the Higgs boson, is to observe the production of Higgs pairs and to measure the Higgs tri-linear coupling $\lambda_{3H}$.
Due to the rarity of di-Higgs production, measuring $\lambda_{3H}$ has proven to be highly challenging. Exclusion limits have been observed using a variety of approaches, including cut-based methods and boosted...
The CMS Level-1 Trigger will be upgraded for the HL-LHC in order to cope with the increased pileup and upgraded detectors. In particular, the inclusion of the tracker will enable offline-like Particle Flow reconstruction at L1, which will allow preserving and even potentially extending the trigger acceptance. This talk will give a brief overview of the upgraded L1 Trigger, the expected...
The identification of Lorentz-boosted Higgs boson is a critical challenge in advancing Higgs pair production studies. This talk provides a comprehensive overview of recent developments on techniques to identify boosted Higgs bosons decaying into tau lepton pairs ($H \to \tau\tau$), on offline reconstruction. Both hadronic ($H \to \tau_{\mathrm{had}}\tau_{\mathrm{had}}$) and leptonic ($H \to...
The Standard Model (SM) is currently the most predictive framework for describing interactions among the fundamental constituents of matter. It includes 19 free parameters, which are measured experimentally, notably with the ATLAS detector at the Large Hadron Collider (LHC) at CERN. These parameters encompass particle masses, phases, and coupling values. One of these couplings, the Higgs boson...
The HH searches are fundamentally constrained by statistical limitations. Enhancing the sensitivity to the HH → bbττ decay channel, the most sensitive process for Higgs pair production in ATLAS, necessitates innovative trigger strategies. Conventional trigger approaches adopted for the HH → bbττ channel in Run 2, focusing solely on di-τ triggers have faced challenges in capturing the full...
After the discovery of the Higgs boson in 2012, the measurements of the Higgs self coupling is still a challenge for current and future experiments in particle physics.
Higgs-boson pair production via gluon fusion is a loop-induced process. In order to increase the accuracy of the theoretical predictions for this process, higher-order corrections are necessary to reduce theoretical...
Jet flavour-tagging algorithms to identify hadronic jets containing b-hadrons are crucial tools for searches of Higgs boson pair production in the ATLAS experiment at the LHC, due to the large branching ratio of the H-->bb process. GN2, the state-of-the-art jet flavour-tagging algorithm developed by ATLAS, delivers a performance that significantly surpasses its predecessors and is expected to...
A precise determination of the Higgs boson self-coupling is a central objective in high-energy physics, offering critical insight into the structure of the Higgs potential and electroweak symmetry breaking. As the Hi-Lumi phase at the LHC aims to tighten constraints on this coupling, next-to-leading order (NLO) electroweak corrections to double Higgs production become a critical component of...
We present searches for nonresonant Higgs boson (H) pair production in the highly Lorentz-boosted phase space with the CMS experiment at the LHC. The analyses are performed in the all-hadronic 4b and bbVV final states, with boosted H pairs identified using novel graph neural network and transformer algorithms for wide-radius jets. Constraints are placed on the strengths relative to the...
This presentation will cover the searches for BSM resonances decaying to a scalar particle H and a standard model (SM) Z boson at the CMS experiment. These searches are one the most powerful probes of the two-Higgs-doublet models at the LHC, and are complementary to the searches for scalars decaying to SM Higgs bosons (h). One of the major differences with respect to the resonant hh/Sh...
REMOTE PRESENTATION
The electron positron Higgs factory is regarded as the highest priority future collider facility, as it could bring decisive data from the Higgs portal to address the long standing Known Unknowns such as the origin of matter, the nature of Dark matter, the naturalness problem, etc. Meanwhile, these facilities, especially the circular ones like CEPC or FCC, could produce...
A precise determination of the Higgs self-coupling represents a cornerstone of the physics program of future colliders because it gives important insights into the shape of the Higgs potential and thus into the evolution of the early universe. This contribution will present an update of the analysis of di-Higgs production in $e^+e^-$ collisions at \mbox{500 GeV} using detailed simulations of...
The HH/SH resonant searches in the bbWW and bbZZ decay channels are presented in this talk. This channel is particularly important for beyond standard model searches because for certain values of the S mass, i.e. below the HH threshold and above the ZZ (or WW) threshold, this could be the SH decay channel with the largest branching ratio. Dedicated searches are carried out at the CMS...
We consider the renormalization group equations within the Standard Model Effective Field Theory and compute two-loop contributions proportional to the top quark Yukawa coupling for the operator generating an effective Higgs-gluon coupling, focusing on the Yukawa-like operator.
These two-loop running effects
are relevant for processes where the effective Higgs-gluon coupling contributes ata...
We present a calculation of the NLO QCD corrections to Higgs boson pair production in vector boson fusion including anomalous couplings. Those couplings are generated by the relevant leading operators of the non-linear Higgs Effective Field Theory (HEFT). We use the Monte Carlo program Whizard interfaced with the amplitude provider GoSam to investigate EFT effects at the level of the total...
A search for a new massive particle X decaying into a Higgs boson H and a second particle, Y using an anomaly detection algorithm is presented. The dataset collected by the CMS experiment in proton-proton collisions at 13 TeV center-of-mass energy is analyzed. The final states with Higgs bosons decaying to a bb quark pair and reconstructed a single large-radius jets are considered. This search...
The ongoing Standard Model Effective Field Theory (EFT) program at the LHC and elsewhere aims at charting the parameter space allowed for deviations from the SM coming from heavy Beyond Standard Model (BSM) physics. Possible hints of New Physics could appear as subtle correlated deviations in several observables but parameterized by a single parameter. Hence, the community has invested great...
We explore the real-singlet extension of the Standard Model without a Z2 symmetry (RxSM) as a framework to address the baryon asymmetry of the Universe and investigate modifications to the Higgs potential. First, we identify regions of parameter space that allow a Strong First-Order Electroweak Phase Transition (SFOEWPT) using the public tools BSMPT, CosmoTransitions, and TransitionListener,...
In my talk, I will show that potentially large higher-order corrections to the trilinear Higgs coupling in Beyond the Standard Model (BSM) scenarios could enhance the interference effects between the non-resonant contribution to Higgs pair production and a resonantly produced heavy scalar. These interference effects have a significant impact on the expected shape of the differential cross...
We study the impact of RGE running and mixing of SMEFT operators on differential observables in $Hj$,$t \bar{t} H$ and $HH$ production at the LHC. We focus on a subset of operators closed under the QCD-induced anomalous dimension matrix and explore the impact of employing a fixed or dynamical scale on the EFT predictions for the Higgs transverse momentum and Higgs pair invariant mass spectra....
REMOTE PRESENTATION
Higgs-boson pairs are dominantly produced via gluon fusion at hadron colliders, i.e. via a loop-induced process. This process will constitute the first direct access to the trilinear Higgs self-interaction. In recent years the NLO QCD corrections involving the full top-mass dependence became available by means of numerical integrations, since analytical methods available so far are not capable...
This poster presents the latest result on ATLAS Run 3 electron and photon in situ energy scale and resolution calibration
We study the prospects for observing exotic decays of the Standard Model (SM) Higgs boson $h$ into light beyond the Standard Model (BSM) scalars $a$ with mass $m_{a} \lesssim m_{h}/2$ in the single Higgs and Higgs pair production channels at the High Luminosity run of the Large Hadron Collider (HL-LHC). Discovery prospects for single Higgs production in the gluon-gluon fusion and vector boson...
A search is presented for non-resonant Higgs boson pair production decaying to multi-lepton final states using 140 fb-1 of proton-proton collision data at centre-of-mass energy 13 TeV, recorded with the ATLAS detector during Run 2 of the LHC. Nine search channels with varying multiplicities of electrons, muons, taus, and photons are combined to determine the observed (expected) limit on the...
The search for Higgs bosons pairs, produced at the LHC, is a fundamental step for the study and understanding of the Higgs field potential, responsible for the spontaneous breaking of the electro-weak symmetry. In fact, the observation of this rare phenomenon would allow us to have an estimate of the cubic term of the potential. However, due to the low number of expected events, many efforts...
We present an updated prospect study on di-Higgs production in the HH→bbγγ decay channel with the ATLAS experiment at the High Luminosity LHC (HL-LHC). The latest projections are based on extrapolating the recent legacy Run 2 ATLAS search and therefore improve over the previous results shown
In this poster, we present a study of di-Higgs production in the HH→bbγγ decay channel using data from the ATLAS experiment. This channel is considered one of the "golden channels" for constraining the Higgs self-coupling, benefiting from the high branching ratio of the H→bb decay and the excellent ATLAS photon triggers. The analysis employs Boosted Decision Trees (BDTs) to define event...
