The Latin American Symposium of High Energy Physics (SILAFAE) congregates the Latin American particle physics community, with the aim of discussing our current knowledge and the future perspectives in particle and astroparticle physics, including topics such as gravitation and cosmology. This is achieved mainly through theoretical and experimental plenary talks, as well as parallel oral contributions and poster presentations.
In this way, the SILAFAE not only keeps the Latin American particle physics community updated in cutting edge knowledge, it also consolidates ties between researchers within and outside the region. In addition, the SILAFAE has the important role of allowing junior scientists within the continent to present their work.
The SILAFAE is now a well established series of international conferences on Particle Physics, currently on its 12th edition. The first SILAFAE started in 1996 in Mérida, Mexico, then in San Juan - Puerto Rico (1998), Cartagena de Indias - Colombia (2000), Aguas de Lindoia - Brazil (2002). In 2004 the V SILAFAE was also organized in Lima - Peru by the National Engineering University (UNI). Then followed Puerto Vallarta - Mexico (2006), San Carlos de Bariloche - Argentina (2009), Valparaíso - Chile (2010), São Paulo - Brazil (2012), Medellin, Colombia (2014) and Antigua - Guatemala (2016).
This year, the XII SILAFAE shall be carried out at the Pontificia Universidad Católica del Perú (PUCP), in Lima, Peru.
The conference fee is:
Early registration is available until 05/10/2018. Please notice that the conference fee is to be paid on a different platform (follow link on the menu).
The following organizations are sponsors of the XII SILAFAE:
I will review Lepton Flavour Universality (LFU), its meaning in the context of the Standard Model, its relation to Lepton Flavour Violation and the implication of its possible failure.
LFU applies to a wide range of processes, at different energy scales, and to a high degree of accuracy. B meson decays mediated by both charged currents and neutral currents have provided hints of violation of LFU. After discussing data and the main theoretical uncertainties involved in the SM
interpretation, I will summarize the results of global fits when new physics is invoked. Effective field theories offer a plausible parametrization of these anomalies and allow for a
consistent discussion of the related constraints. As explained in this talk, these include both high-energy collider physics and low-energy processes arising from purely radiative effects.
A review of recent results of the LHCb experiment will be made, tentatively covering the current status of the so-called weak anomalies in lepton flavor universality and angular analysis of b--> s ll decays, of CP-violation and b- and c-quark spectroscopy, and of low-mass new particle searches. Future perspectives shall also be outlined
ALICE is an experiment designed to study the physics of strongly interacting matter and the quark-gluon plasma (QGP) in nucleus-nucleus collisions at the CERN’s LHC. During the Run1 and Run 2 data taking (2010-2018), ALICE has collected valuable data for proton-proton, proton-lead, lead-lead and Xenon-Xenon collisions at different energies. In the presentation, we will summarize the main results towards understanding the high temperature and high energy density matter formed in these collisions, covering observables from the soft sector (bulk particle production and correlations), hard probes (charmed hadrons and jets) and signatures of possible collective effects in pp and p-Pb collisions with high multiplicity. The ALICE collaboration is currently preparing the upgrade of the experiment for Run 3, we will present the planned upgrades together with the future physics outlook.
New and recent results from the ATLAS programme of studies in EW physics with open beauty are presented. Particular attention will be given to measurements involving FCNC processes in Bs and Bd mesons decays ( that are sensitive to New Physics contributions through corrections to the EW loop amplitudes) and to studies of CP violation in the Bs sector.
The most recent results from ATLAS are presented, including prospects for HL-HLC.
The Nambu--Jona-Lasinio model is the classic model of nonperturbative physics generating an effective Higgs field as dynamical composite giving symmetry breaking and mass generation. We discuss the line of supersymmetric versions of NJL type models we studied in the recent years and their possible phenomenological applications in the setting of the supersymmetric standard model. The nontrivial nature of the notion of supersymmetrization for both the case of spin zero and spin one composites will also be illustrated.
We study a scenario inspired by natural supersymmetry, where neutrino data is explained within a low-scale seesaw scenario. We extend the MSSM by adding light right-handed neutrinos and their superpartners, the R-sneutrinos, and consider the lightest neutralinos to be higgsino-like.
We consider the possibility of having an R-sneutrino as lightest supersymmetric particle. Assuming that some squarks and gauginos are heavy, we systematically evaluate the bounds on slepton and squark masses due to existing LHC data.
Despite the absence of experimental evidence, weak-scale supersymmetry remains one of the best motivated and studied Standard Model extensions. This talk summarises recent ATLAS results on searches for SUSY, including strong production and electroweak production. Strong limits can be set on gluino and squark (including stop) production with recent data. Several searches explore long-lived scenarios that may be detected through abnormal specific energy loss, appearing or disappearing tracks, displaced vertices, long time-of-flight or late calorimetric energy deposits.
Positrons beam dump experiments have unique features to search for very narrow resonances coupled superweakly to $e^+ e^-$ pairs. Due to the continue loss of energy from soft photon bremsstrahlung, in the first few radiation lengths of the dump a positron beam can continuously scan for resonant production of new resonances via $e^+$ annihilation off an atomic $e^-$ in the target. We explore the foreseeable sensitivity of the Frascati PADME experiment to searching, with this resonance annihilation technique, the $17$ MeV dark photon invoked to explain the $^8$Be anomaly in nuclear transitions.
Many theories beyond the Standard Model predict new phenomena accessible by the LHC. Searches for new physics models are performed using the ATLAS experiment at the LHC. The non-Dark Matter related results reported here use the pp collision data sample collected in 2015 through 2018 by the ATLAS detector at the LHC with a center-of-mass energy of 13 TeV.
In this work we present a simple extensions of the Standard Model
that contain, as the only new physics component, a massive spin-one matter field in a non-trivial representation of SU(2)_L. In the first case, we consider a vector field in the adjoint representation. In order
to be consistent with perturbative unitarity, the vector field
must be odd under a Z_2 symmetry. Radiative corrections make
the neutral component of the triplet (V^{0}) slightly lighter than
the charged ones. We show that V^{0} can be the dark matter particle while satisfying all current bounds if it has a mass between 2.8 and 3.8 TeV.
We present the current limit on the model parameter space from highly
complementary experimental constraints including dark matter relic density measurement, dark matter direct and indirect detection searches, LHC data on Higgs couplings to photons and LHC data on disappearing track searches. We also show that the two-dimensional parameter space can be fully covered by disappearing track searches at a future 100 TeV hadron collider, which will probe, in particular, the whole mass range relevant for dark matter, thus giving an opportunity to discover or exclude the model.
In a second mode, we consider a vector field in the fundamental representation of SU(2)_L. In this case we found that the model is more severely constrained.
We propose a new extension of the Standard Model by a U(1)B−L gauge symmetry in which the anomalies are canceled by two right-handed neutrinos plus four chiral fermions with fractional B-L charges. Two scalar fields that break the B-L symmetry and give masses to the new fermions are also required. After symmetry breaking, two neutrinos acquire Majorana masses via the seesaw mechanism leaving a massless neutrino in the spectrum. Additionally, the other new fermions arrange themselves into two Dirac particles, both of which are automatically stable and contribute to the observed dark matter density. This model thus realizes in a natural way, without ad hoc discrete symmetries, a two-component dark matter scenario. We analyze in some detail the dark matter phenomenology of this model. The dependence of the relic densities with the parameters of the model is illustrated and the regions consistent with the observed dark matter abundance are identified. Finally, we impose the current limits from LHC and direct detection experiments, and show that the high mass region of this model remains unconstrained.
The dipole approach provides all the necessary means for a universal treatment of both inclusive and diffractive reactions. In this presentation, I will classify various sources of diffractive factorisation breakingin hadronic collisions in both diffractive Abelian and non-Abelian radiation as apparent in the dipole picture, as well as give a short overview of the recent advances in treatment of such diffractive production processes as diffractive Drell-Yan and di-jet production.
In this work we test a multivariate method to differentiate between particle showers produced by cosmic rays and by gamma rays at TeV energies, using CORSIKA simulations. The aim is to solve the dominant hadron flux background problem when looking for gamma-ray signals measured by different experiments. The results of this work can be applied to the study of Gamma-Ray Bursts (GRBs). GRBs emit very energetic photons, which after interacting in the Earth's atmosphere, produce a large detectable electromagnetic cascade of secondary particles.
We simulate events produced by photons, the signal, and protons, the most abundant cosmic-ray background. We extract several parameters from fitting particle air-shower longitudinal profiles, characterizing the simulated showers. Some of the most important fit parameters are the shower maximum (Xmax), the width of the shower (FWHM), the asymmetry parameter, the maximum number of particles and the shower start. Experiments using fluorescence detectors can measure this longitudinal profile of the shower.
The method to differentiate showers is based on a multivariate analysis using the TMVA package, which improves individual cuts. We use a sample that covers an energy range from 100 GeV to 10 TeV with different spectra to train and test different multivariate methods. We find that the Boosted Decision Trees (BDT) method was the best for distinguishing signal from background. Using tight cuts on the BDT we obtain a 1000 background rejection capability.
The aim of the present work is to correlate highly energetic, short lived events in the radio
wave spectrum, known as Fast Radio Bursts (FRB), and compact radio sources known as
Faranoff-Riley 0 (FR-0) with gamma rays using data from the Fermi satellite.
FRB's origin is still unknown, although, given their spatial distribution, an extragalactic origin is
suspected. Up to date, only one FRB (FRB121102) has been identified due to its repeating
nature.
The identification of a gamma ray counterpart for these events would put them as candidates
to most energetic observed event, while providing important clues as to their origin.
The Faranoff-Riley classification divides radio sources in Class I (luminosity decreases with
distance to the center), Class II (luminosity increases in the lobes) and Class 0 (similar to Class I
but with a large deficit of extended radio emission). The study of FR-0s in other wavelengths is
crucial to better understand the source's engine.
In this work, we model gamma ray fluxes of both FRBs and FR-0s to find a significant
correlation. This analysis is made by varying the time windows (in the case of FRBs), the
various models used (e.g: power law, log parabola, cutoff, etc) and searching for an optimal set
of parameters to maximize the test statistics for the excess flux in gamma rays.
The Latin American Giant Observatory (LAGO) consists of a network of water Cherenkov detectors (WCDs) with the aim of measuring the secondary cosmic rays flux at ground level. It is distributed across 10 countries in Latin America, from Mexico to Antarctica, at several altitudes, from sea level to 5200 m.a.s.l. The decentralized nature of this network has forced the development of a simple and robust detector, as well as an autonomous, synchronized acquisition system, with the capacity to perform on-site analysis.
In this talk we will discuss LAGO's scientific programs: high energy astrophysics, space weather and ground level radiation; also, the LAGO training program, which includes the design, operation and simulation of the detectors. Finally, we present the current state of the detectors network, some results and future prospects.
We built desktop particle detectors based on a design from MIT. We use them for measuring two characteristics of atmospheric muons: their angular distribution at sea level and their attenuation for lead and concrete layers. We also made a comparison between the actual measurements and the expected results from simulations based on Geant4. Finally, we explored the application of the detectors to the measurement of pure beta-sources’ activity, allowing for an effective, simple dosimetry and radioactive source recognition method.
The influence of the extra dimension on the static equilibrium configurations and the stability against radial perturbations are analyzed. These studies are investigated by using the stellar structure equations and the radial perturbation equations, both modified for a $d$-dimensional spacetime. We obtain that the spacetime dimension influences in both structure and stability of an object, whose fluid contained in it follows a linear equation of state, in this case the MIT bag model equation of state is considered. For an interval of central energy densities $\rho_c\,G_d$ and total masses $MG_d/(d-3)$, when the dimension is increased the stars gain more stability. We also show that the value of $\rho_c\,G_d$ used to obtain the maximum value of $M{G_d}/(d-3)$ is the same used to obtain the zero eigenfrecuency of oscillation, i.e., the peak value of $M{G_d}/(d-3)$ marks the onset of instability. This indicates that the necessary and sufficient conditions to recognize regions constructed by stable and unstable equilibrium configurations against radial perturbations are respectively $dM/d\rho_c>0$ and $dM/d\rho_c<0$.
We analyze in detail a previous proposal by Dvali and Gómez that black holes could be treated as consisting
of a Bose-Einstein condensate of gravitons. In order to do so we extend the Einstein-Hilbert action with a
chemical potential-like term, thus placing ourselves in a grand-canonical ensemble. The form and characteristics
of this chemical potential-like piece are discussed in some detail. We argue that the resulting equations of motion
derived from the action could be interpreted as the Gross-Pitaevskii equation describing a graviton Bose-Einstein
condensate trapped by the black hole gravitational field. After this, we proceed to expand the ensuring equations
of motion up to second order around the classical Schwarzschild metric so that some non-linear terms in the metric
fluctuation are kept. Next we search for solutions and, modulo some very plausible assumptions, we find out that
the condensate vanishes outside the horizon but is non-zero in its interior. Inspired by a linearized approximation
around the horizon we are able to find an exact solution for the mean-field wave function describing the graviton
Bose-Einstein condensate in the black hole interior. After this, we can rederive some of the relations involving
the number of gravitons N and the black hole characteristics along the lines suggested by Dvali and Gómez.
We analyze the gravity-electromagnetic interaction in a pure Ho\v{r}ava-Lifshitz framework. To do so we formulate the Ho\v{r}ava-Lifshitz gravity in $4+1$ dimensions and perform a Kaluza-Klein reduction to $3+1$ dimensions. We use this reduction as a mathematical procedure to obtain the $3+1$ coupled theory, which at the end is considered as a fundamental, self-consistent, theory. The critical value of the dimensionless coupling constant in the kinetic term of the action is $\lambda=1/4$. It is the kinetic conformal point for the non-relativistic electromagnetic-gravity interaction. In distinction, the corresponding kinetic conformal value for pure Ho\v{r}ava-Lifshitz gravity in $3+1$ dimensions is $\lambda=1/3$. We analyze the geometrical structure of the critical and noncritical cases, they correspond to different theories. The physical degrees of freedom propagated by the noncritical theory are the transverse traceless graviton, the transverse gauge vector and two scalar fields. In the critical theory one of the scalars is absent, only the dilaton scalar field is present. The gravity and vector excitations propagate with the same speed, which at low energy can be taken to be the speed of light. The field equations for the gauge vector in the non-relativistic theory have exactly the same form as the relativistic electromagnetic field equations arising from the Kaluza-Klein reduction of General Relativity, and are equal to them for a particular value of one of the coupling constants. The potential in the Hamiltonian is a polynomial of finite degree in the gauge vector and its covariant derivatives.
We find a large class of scalar field theories in curved spacetime which admit massive configurations with vanishing energy momentum tensor (stealth fields), therefore they do not feedback the gravitational background. We show also that other massive modes contained in these theories possess rescaled energy momentum tensors with respect to the standard (Klein-Gordon) theory, i.e. whose strenght can be smoothed or magnified accoding to the value of a single parameter, equivalent to the mass of the stealth configuration. Our result demonstrates that matter fields may produce non-standard effects in their gravity backgrounds, i.e. different of those expected from general relativity. Talk based in https://arxiv.org/abs/1805.04621
The breakdown of Lorentz symmetry has been pointed out as a candidate to account for quantum gravity effects. The strong suppression at low energies, has lead to consider the interlink between effective field theory and ultra high precision experiments. To begin with, we motivate such violations within effective field theory and describe how these effective terms are implemented. Recently, higher-order operators have attracted a lot of interest, since one can consider higher energies in the search. We explain why and how these terms can lead to issues on unitarity and renormalization. We show the main ingredients in the formulations to deal with these issues.
We show that in the presence of the torsion tensor $S^k_{\phantom{k}ij}$, whose existence is required by the consistency of the conservation law for the total angular momentum of a Dirac particle in curved spacetime with relativistic quantum mechanics, the quantum commutation relation for the four-momentum is given by $[p_i,p_j]=2i\hbar S^k_{\phantom{k}ij}p_k$.
We propose that this relation replaces the integration in the momentum space in Feynman diagrams with the summation over the discrete momentum eigenvalues.
We derive a prescription for this summation that agrees with convergent integrals:
$\int\frac{d^4p}{(p^2+\Delta)^s}\rightarrow 4\pi U^{s-2}\sum_{l=1}^\infty \int_0^{\pi/2} d\phi \frac{\sin^4\phi\,n^{s-3}}{[\sin\phi+U\Delta n]^s}$,
where $n=\sqrt{l(l+1)}$ and $1/\sqrt{U}$ is a constant on the order of the Planck mass, determined by the Einstein-Cartan theory of gravity.
We show that this prescription regularizes ultraviolet-divergent integrals in loop diagrams.
We extend this prescription to tensor integrals and apply it to vacuum polarization.
We derive a finite, gauge-invariant vacuum polarization tensor and a finite running coupling that agrees with the low-energy limit of the standard quantum electrodynamics.
Including loops from all charged fermions, we find a finite value for the bare electric charge of an electron: $\approx -1.22\,e$.
Torsional regularization, originating from the noncommutativity of the momentum and spin-torsion coupling, therefore provides a realistic, physical mechanism for eliminating infinities in quantum field theory: quantum electrodynamics with torsion is ultraviolet complete.
We will provide a short introduction to the current status of neutrino knowledge with emphasis on the long-baseline experiments. An extended introduction to the DUNE experiment will follow, addressing the current status of the project, including recent results for its several R&D setups. We will end discussing the overwhelming results DUNE could achieve in general for the neutrino physics.
After the discovery of the Higgs boson in summer 2012, the understanding its properties has been a high priority of the ATLAS physics program. Measurements of Higgs boson properties sensitive to its production processes, decay modes, kinematics, mass, and spin/CP properties based on pp collision data recorded at 13 TeV are presented. The analyses in several decay channels will be described and the results of the combination of different decay channels will be shown.
In this work we study the effects of new physics in double Higgs production at future $e^+ e^-$ colliders. In particular, we consider the possibility of an enhancement due to the contribution of SM dimension-six effective operators. We perform this study for several benchmarks of energy and integrated luminosity related to several proposed linear colliders such as CLIC, ILC and FCC-ee. We derive expected bounds on the effective field theory coefficients for these different scenarios.
Several theories beyond the Standard Model predict the existence of additional neutral or charged Higgs particles, as well as decays of the Higgs boson that are either forbidden or strongly suppressed in the SM.
Results from selected recent searches for additional Higgs bosons in different production processes and decay modes, and for BSM decays of the 125 GeV-Higgs boson will be presented.
In this work, we categorize and discuss the maximum contributions to the muon magnetic moment $a_{\mu}$ as well as to the Yukawa and triple Higgs couplings in the flavour-aligned two-Higgs doublet model (2HDM). We focus on the most promising case of a light pseudoscalar Higgs A with large Yukawa couplings to leptons and quarks. By taking into account experimental constraints from LHC, Higgs and flavour physics, we find maximum possible Yukawa couplings of a light A of around $50\cdots 100$ (leptons) and $O(0.5)$ (quarks). An overall maximum for $a_{\mu}$ of more than $45\times 10^{−10}$ is possible in a very small parameter region around $M_{A} = 20 \,GeV$. For $M_{A}$ up to $100\, GeV$, the maximum possible value of $a_{\mu}$ is compatible with the currently observed deviation if the A couplings to quarks and leptons are both large, making this scenario promising for LHC searches. We also analyse the subleading bosonic two-loop contributions to $a_{\mu}$ , finding values up to $3\times 10^{−10}$.
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The chromomagnetic dipole moment (CMDM) and chromoelectric dipole moment (CEDM) of the top quark are calculated at the one-loop level in the framework of the two-Higgs doublet model with four fermion generations (4GTHDM), which is still consistent with experimental data and apart from new scalar bosons ($H^0$, $A^0$, and $H^\pm$) and quarks ($b'$ and $t'$) predicts new sources of $CP$ violation via the extended $4\times 4$ CKM matrix. Analytical expressions for the CMDM and CEDM of a quark are presented both in terms of Feynman parameter integrals, which are explicitly integrated, and Passarino-Veltman scalar functions, with the main contributions arising from loops carrying the scalar bosons accompanied by the third- and fourth-generation quarks. The current bounds on the parameter space of the 4GTHDM are discussed and a region still consistent with the LHC data on the 125 GeV Higgs boson and the oblique parameters is identified. It is found that the top quark CMDM, which is induced by all the scalar bosons, can reach values of the order of $10^{-2}$--$10^{-1}$. As for the top quark CEDM, it only receives contributions from the charged scalar boson and can reach values of the order of $10^{-20}$--$10^{-19}$ ecm for relatively light $m_{H^\pm}$ and heavy $m_{b'}$, with the dominant contribution arising from the $b$ quark. The CEDM would be the most interesting prediction of this model as it can be larger than the value predicted by the usual THDMs by one order of magnitude.
Standard-model elds and their associated electroweak Lagrangian are equivalently expressed in a shared spin basis. The scalar-vector terms are written with scalar-operator components acting on quark-doublet elements, and shown to be parametrization-invariant. Such terms, and the t- and b-quark Yukawa terms are linked by the identification of the common mass-generating Higgs operating upon the other fields. Thus, the customary vector masses are related to the fermions', fixing the t-quark mass mt with the relation mt^2+mb^2= v^2/2 either for maximal hierarchy, or given the b-quark mass mb. A sum rule is derived for all quark masses that generalizes this restriction. An interpretation follows that electroweak bosons and heavy quarks belong in a multiplet.
arXiv:1701.01191
To be published, Phys. Rev. D. (2018)
we present a study of forward backward multiplicity correlations in proton-proton collisions using PYTHIA event generator, at LHC energies. Detailed analysis is presented splitting data samples into soft and hard QCD processes, as well as, their comparisons of the correlation computed for short and long range pseudorapidity regions. Each region is analyzed taking into account effects on the color reconnection and independently multiple parton interactions. We show that a combination of those effects is required to explain last measurements
on proton-proton data, furthermore, the extraction of the strength of color reconnection and taking events with ranges of the number of multiple partons interactions brings us also the possibility to predict the results to energies not reached in the experiment.
ALICE is unique among experiments at the LHC because of its excellent particle identification capabilities, unmatched tracking performance, low transverse momentum threshold and an extended coverage of twelve units of pseudorapidity to detect the presence of particles produced in the collisions. In particular, the ALICE pseudorapidity range has been updated in the second run of the LHC, due to the addition of two new scintillation stations (AD). The new pseudorapidity regions are: [-7.0, -4.9] and [+5.1, +6.3]. The inclusion of these regions allows ALICE to achieve better sensitivities for studying low mass diffractive processes, in comparison with its previous capabilities. In this talk we review the ALICE diffractive cross section measurements for pp at 7 TeV with data from the first LHC run and the potential for improving these measurements in the second run, taking into account the new AD scintillation stations.
There are several different predictions for the behaviour of the gluon distribution in nuclei at small Bjorken x and experimental data are needed to choose among them. This is achieved by measuring the cross section of processes specially sensitive to this parton distribution.
The high flux of photons from lead ions at the LHC allows us to study photon-induced reactions in ultra-peripheral collisions (UPC) of Pb-Pb nuclei, in particular of those producing a J/ψ meson exclusively. The study of these collisions, where projectiles do not overlap, provides information about the initial state of nuclei.
The newest ALICE results on vector meson photoproduction are presented. The increased statistics and higher collision energy of $\sqrt{s}$=5.02 TeV in Run 2 allow us to put new constraints on available models.
The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, it gives us the unique opportunity to probe the properties of bare quarks at the Large Hadron Collider. This talk will present highlights of a few recent precision measurements of the top quark using 13 TeV collision data: top-quark pair and single top production cross sections, including differential distributions and production in association with bosons, will be presented alongside top quark properties measurements. These measurements, including results using boosted top quarks, probe our understanding of top quark production in the TeV regime. Measurements of the top quark mass are also presented.
I will discuss some of the ongoing experiments for dark matter direct detection, which have a big emphasis on WIMPS. I will also discuss the newly developed experimental techniques that are now making possible the search for dark matter candidates beyond the wimp, providing a new window into the dark sector.
The first years of running of the CERN LHC marked a real milestone in particle physics with the discovery of the long sought Higgs boson. The LHC is delivering a wealth of high-quality data at an increased centre-of-mass energy, which, so far, shows and impressive agreement with the expectation from the Standard Model (SM) without clear evidence for new physics signals.
In general, the key word for indirect physics searches for the next years will be precision, since new physics could manifest itself through small deviations from SM behavior. In this talk I will present the state of the art theoretical (QCD and SM) toolkit for precision physics at the LHC.
Reliable estimates of the allowed range for axion couplings to photons, nucleons and electrons are of major importance for determining the viable axion mass window as well as to focus experimental axion searches.
We show that in a class of generalized DFSZ axion models with generation dependent Peccei-Quinn charges the axion couplings to nucleons and electrons can be simultaneously suppressed. Astrophysical limits from the SN1987A burst duration and from white dwarf cooling can therefore be relaxed, and as a consequence for such an astrophobic axion a mass window up to O(0.1) eV remains open. Since the axion-photon coupling remains sizeable, the proposed IAXO helioscope will become crucial to search for axions of this type.
An unavoidable consequence of astrophobia are flavor off-diagonal axion couplings at tree-level, so that experimental limits on flavor-violating processes can also provide a powerful tool to constrain this scenario. The astrophobic axion can be a viable dark matter candidate in the heavy mass window, and can also account for anomalous energy loss in stars.
We seek to study how the observed spectrum of cosmological photons is modified if a theory that considers new particles is incorporated,
analogues to the usual photons, called Hidden Photons and axion-like particles.
To study these possible modifications, we introduce a model that contains parameters that correspond to the masses and couplings for both new particles. These being free parameters, we seek to find the best adjustment of the spectrum observed with the modifications to the usual black body spectrum and thus obtain regions of exclusion, in which we can observe the possible validity of the extended theory.
Then we need to improve these regions of exclusion, incorporating new interactions in the process of photon oscillation to Hidden Photon and axions, in addition to improving our understanding of the cosmological processes occurring in the evolution of the universe, such as recombination and reionization. [1-2]
As an experimental test, the model is studied from a point of view where the oscillation between particles occurs in an empty environment.
These experiments are of the Aharonov-Bohm type where they study the existence of electric and magnetic fields in the different regions of space, where it can be inferred if there is a presence of new particles. [3]
The dark matter problem is one of the major subjects of physics these days. The search for hints in the high and low mass range are intense. A quite popular candidate is the axion, a very light hypothetical particle that can only account for the whole dark matter in a window of mass around the $\mu$eV. Recently has been found that one way to open up this window is if the axion is coupled to a massless dark photon. In this talk, we would like to review the mechanisms in which axions and dark photons can be independently very good cold dark matter candidates, and also show a model where they can both be produced in the early universe, and therefore have them both as the dark matter.
The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as their signature. The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC collisions. The results of these searches on the 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.
Searches in CMS for dark matter in final states with invisible particles recoiling against visible states are presented. Various topologies and kinematic variables are explored, including jet substructure as a mean of tagging heavy bosons. The focus of the talk is the recent results obtained using data collected at Run-II of the LHC.
Static coordinates can be convenient to solve the vacuum Einstein's equations in presence of spherical symmetry, but for cosmological applications comoving coordinates are more suitable to describe an expanding Universe, especially in the framework of cosmological perturbation theory (CPT).
Using CPT we develop a method to transform static spherically symmetric (SSS) modifications of the de Sitter solution from static coordinates to the Newton gauge.
We test the method with the Schwarzschild de Sitter (SDS) metric and then derive general expressions for the Bardeen's potentials for a class of SSS metrics obtained by adding to the de Sitter metric a term linear in the mass and proportional to a general function of the radius. Using the gauge invariance of the Bardeen's potentials we then obtain a gauge invariant definition of the turn around radius.
We apply the method to an SSS solution of the Brans-Dicke theory, confirming the results obtained independently by solving the perturbation equations in the Newton gauge. The Bardeen's potentials are then derived for new SSS metrics involving logarithmic, power law and exponential modifications of the de Sitter metric. We also apply the method to SSS metrics which give flat rotation curves, computing the radial energy density profile in comoving coordinates in presence of a cosmological constant.
Wilson loops have played a central role in the development of gauge/gravity dualities. We consider the vacuum expectation values of 1/2-BPS circular Wilson loops in N=4 super Yang-Mills theory in the totally antisymmetric representation of the gauge group U(N) or SU(N). Localization and matrix model techniques provide exact, but rather formal, expressions for these expectation values. We extract the leading and sub-leading behavior in a 1/N expansion with fixed 't Hooft coupling starting from these exact results. This is done by exploiting the relation between the generating function of antisymmetric Wilson loops and a finite-dimensional quantum system known as the truncated harmonic oscillator.
We extend a holographic bottom-up model to reproduce in-medium scaling law for hadron masses, and we use it to study electromagnetic form factors and another hadron properties in nucleus. As an example, we consider properties for protons.
In this work, we discuss how to develop a model for the drag force using the so-called AdS/QCD soft wall model. The strong medium will be modeled holographically by and AdS-Black hole metric (Schwartzchild and Reissner Nordstrom) in the presence of a static quadratic dilaton. The parton in this approach is given by Chan-Paton charge at the end of an open string living in the background space. Kinematical and dynamical properties of the string will give rise to the dynamic properties of the parton in the strong media.
In this talk we will present how to use the AdS/CFT correspondence to compute analytically the masses of the scalar and higher even spin glueball with P=C=+1 using a single mass equation.
The approach considered here is based on a modified dynamic version of the Softwall Model with anomalous dimension contribution.
Furthermore, from the even glueball masses, we also achieved the Regge trajectory related the pomeron in agreement with other approaches.
The fundamental description of nature, beyond the Standard Model (SM), may include heavy neutrinos that mix and thus allow processes in which lepton flavor is not preserved. We investigate the impact of charged currents that couple heavy gauge bosons to heavy neutrinos and SM leptons on neutrinoless lepton-flavor-violating decays of SM leptons into three charged leptons. We implement our expressions for the leading contributions to Br(lα → lβ lσ lσ), which hold for either Dirac or Majorana neutrinos, to neutrinoless trilepton decays of the muon and so determine sets of masses of heavy neutrinos and the heavy gauge boson, within GeVs to few TeVs, that are consistent with the upper bounds provided by the SINDRUM Collaboration.
One of the open questions in particle physics is to know the nature of neutrinos, that is, to know if they are Dirac or Majorana particles. One of the most accepted models for the generation of neutrino mass is the Seesaw model, if we also consider an approximate lepton number symmetry, these can be tested in colliders. Here we consider an extension of the standard model, where we add two heavy neutrinos. These Majorana fermions will be considered highly degenerate, this is what we will call Pseudo-Dirac neutrinos. We consider the production of heavy neutrinos at the ILC, where its displaced vertex can be a golden signal. We will connect the splitting of the masses of heavy neutrinos with a forward-backward charge asymmetry and we will show that the constraints in these splittings can be lower than the known bounds.
We study the capability of angular and polarization observables to disentangle different new physics contributions to the production of heavy sterile Majorana neutrinos in the lepton number violating channels $e^{-}p\rightarrow l_{j}^{+} + 3 jets$ ($l_j\equiv e ,\mu $) and $e^{+}e^{-}\rightarrow \tau^{+} \tau^{+}+ 4 jets$ in electron-proton and electron-positron colliders. This is done investigating the angular and polarization trails of effective operators with distinct Dirac-Lorentz structure contributing to the Majorana neutrino production, which parameterize new physics from a higher energy scale.
We study the feasibility of observing deviations from the CPT symmetry owing to quantum decoherence and in the framework of the neutrino oscillations. Taking into account the open system approach, and considering non-diagonal decoherence matrizes, we study all the cases in which CPT violation (CPTV) terms that could be arising in the neutrino oscillation probabilities. Moreover, and based on the information from the muon neutrino/antineutrino channels, we put on trial all the CPTV cases using the DUNE experiment. For the optimal case, we find 5 $\sigma$ of confidence for $\Gamma (E / \mathrm{GeV})^{n} \sim 13.1 \times 10 ^{-23} \mathrm{GeV}$, $4.6 \times 10 ^{-23} \mathrm{GeV}$ $2.1 \times 10 ^{-23} \mathrm{GeV}$ y $0.8 \times 10 ^{-23} \mathrm{GeV}$ for $n = -1$, 0, 1 and 2 respectively.
In this talk I will discuss the impact of recent COHERENT data on neutrino generalized interactions. I will show that scalar nuclear currents are the most constrained, while vector and tensor still allow for sizable effective couplings. I will discuss as well some implications of vector generalized interactions and will comment on the impact they have in the data fit.
The consequences of introducing matter effects into the neutrino visible decay scheme are studied. To this end, we select two
baselines for which matter effects have to be considered:1300 km (DUNE) and 7650 km(considering an hypothetical
beam aimed towards ANDES). The matter effects are almost unnoticeable for the visible decay contribution DUNE, being sizable at ANDES. We also carry out a realistic analysis taking DUNE as a context, considering $\nu_\mu$ disappearance and $\nu_e$ appearance channels, for both FHC and RHC modes. The sensitivity to the decay constant $\alpha_3$ can be as low as $2 \times 10^{-6}$ eV$^2$ at $90 \%$ C.L., depending on the neutrino masses and type of coupling (scalar, pseudo-scalar or both). Lastly, we asses the impact of neutrino decay in the determination of $\theta_{23}$ and $\delta_{CP}$, and find that the best-fit value of $\theta_{23}$ can move from a true value at the lower octant towards the higher octant.
In this talk we review the BTZ type wormhole, the Thermofield
Double State (TFD) and the Averaged Null Energy Condition (ANEC) violation which is a prerequisite for all traversable wormholes. Finally we comment on traversable charged rotating wormholes in AdS space.
From a modified General Relativity model named Delta Gravity (DG), that is based on a new Einstein-Hilbert action based on a new symmetry symbolized as $\tilde{\delta}$, we found two equations with the same structure as the Friedmann Equations. These equations let us establish a relation between the two free parameters of the DG theory, and the ``Dark Energy'' density, and we can conclude that one of these parameters, $L_2$, is strictly causing the Accelerating Expansion of the Universe.
These equivalent Friedmann Equations are obtained with a rearrangement of the (DG) motion equations. In this way, a new energy density appears naturally and it can be associated to Dark Energy in the $\Lambda$CDM model.
Introduction
We have been computing the scalar modes of the temperature fluctuations of the CMB in the context of Delta Gravity (DG) [1,2]. For this purpose we developed the perturbation theory of the equations of motions of this theory and studied the propagation of photons in the extended FRWL background using the hidrodynamical approximation and the sharp transition approximation at the time of last scattering [3].
As in General Relativity (GR), we could split the temperature fluctuation in an early'',
late'' and ``ISW'' term, which we have probed they are gauge invariant. Then we assumed that all scalar contributions to the fluctuations were dominated by a single mode and we can study the temperature multipole coefficients.
Final calculations are in progress.
The Model
In DG photons follow null geodesics in an effective metric, if we consider a light ray travelling toward the center of this coordinate system from the direction $\hat{n}$, this ray will have a co-moving radial coordinate $r$ related to $t$ by:
\begin{equation}
0={\bf g}{\mu\nu}dx^{\mu}dx^{\nu}=-(1+\kappa_2 F(t)+E(r\hat{n},t)+\kappa_2 \tilde{E}(r\hat{n},t))dt^2\+(R^2(t)(1+\kappa_2 F(t))+h{rr}(r\hat{n},t)\kappa_2\tilde{h}_{rr}(r\hat{n},t))dr^2\,,
\end{equation}
where $E,\;\tilde{E},\;h_{rr}$ and $\tilde{h}_{rr}$ are perturbations. $\kappa_2$ is just a parameter which can be $0$ (GR case) or $1$ (DG case), and it has no physical meaning because we can always re-scale the fields in the Delta sector.
If we make the approximation of a sharp transition from thermal equilibrium to complete transparency at a moment $t_L$ of last scattering then we get
\begin{equation}
\left(\frac{\Delta T(\hat{n})}{T_0}\right)^S=\left(\frac{\Delta T(\hat{n})}{T_0}\right)^S_{\text{early}}+\left(\frac{\Delta T(\hat{n})}{T_0}\right)^S_{\text{late}}+\left(\frac{\Delta T(\hat{n})}{T_0}\right)^S_{\text{ISW}}\,.
\end{equation}
Each term is gauge invariant under transformations that leave ${\bf g}_{i0}$ equal to zero.
The ``late'' term only affects terms in the multipole expansion of the temperature correlation function with $l=0$ and $l=1$, so it can be ignored if from now on we consider only multipole orders $l\geq 2$. Besides, the integrate Sachs-Wolfe effect can also be neglected, because this effect is important only for relatively small values of $l$, say $l<20$, where cosmic variance intrudes on measurementes of $C_{TT,l}^S$.
Finally, we are now calculating higher orders of the temperature multipole coefficients for the scalar modes.
In the present work, we investigate the scale-dependence of the FLRW cosmology at the level of the effective action in the presence of a cosmological constant. We promote the classical parameters of the theory, $\{G_0, (\cdots)_0 \}$, to scale-dependent couplings, $\{G_k, (\cdots)_k\}$, and then we solve the corresponding effective Einstein's field equations. To close the system of equations we impose the "null energy condition". Furthermore, perfect-fluid like parameters are induced via the scale-dependent gravitational coupling. Finally, to exemplify the effect of the running of the couplings on the properties of the scale-dependent FLRW solution in the underlying theory, we present a few concrete examples.
The Cohen and Glashow proposal, Very Special Relativity (VSR), explain the existence of a neutrino mass without introducing new particles and leptonic number violation, only reducing the symmetry from Lorentz to a subgroup, SIM(2). The main feature of this model is the existence of a privileged direction, given by a null vector. In this framework we have explored Quantum Electrodynamics in order to find an observable which we could test the feasibility of this model. We have computed self-energies of photon and electron with new Feynman rules. A calculation in the Coulomb Scattering is presented and we have the same features found in the standard model. In addition, the Photon-Photon Scattering is presented. In the latter case, we have new signals of this null vector, but some problems with the choice of a prescription in the integration are discussed.
I will review two recent developments in astroparticle theory and phenomenology that are not meant to be exhaustive in any way, but are connected to some of the particle physics covered in this conference.
First, cosmic rays have been observed up to macroscopic energies of about 50 Joules, presumably in one elementary particle. The existence of such particles pose formidable challenges and exciting prospects at the same time: Their origin and sources have not been identified yet, but they already allow to test physics at center of mass energies unattained in the laboratory, albeit in a rather indirect way. We will give an overview over possible sources and
acceleration mechanisms, issues related to cosmic ray mass composition and hadronic interaction models, and the role of secondary gamma-rays and neutrinos produced in primary cosmic ray interactions.
Second, axion-like particles, partly motivated by the strong CP problem, have recently gained attention as dark matter candidates and are searched for by shining light through a wall experiments and so called haloscopes and helioscopes based
on their two-photon couplings. They also provide interesting open theoretical problems ranging from their production in the early Universe to the large scale dark matter distribution, down to "axion stars", they would give rise to. Some of these aspects
will be reviewed.