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The main goal of this workshop is to bring experimentalists and theorists together to reflect on the current and future opportunities in the field of particle physics. Subjects to be discussed include Higgs, QCD, flavor and BSM physics at the LHC. The target participants are researchers in Brazil and Argentina directly involved in this field, to stimulate close and profitable collaborations for the next decade. This would be the first workshop of this kind in the region, and we hope that indeed it could develop into a Workshop with a regular frequency.
Financial support for lodging expenses can be provided to a limited number of participants. Applications for financial support must be addressed to icas@unsam.edu.ar before March 10. (closed)
NEW
In order to stimulate collaborations, we invite you to propose a short presentation (12’+3 minutes for discussion, one talk per research line/group) describing the main line of your work.
Call for presentations is open! (click in Call for abstracts) Deadline APRIL 9
We will organize more topical working group encounters during the meeting according to the interests informed at the registration, with the main idea of encouraging further discussions.
Lodging and Venue Location
The easiest way to arrive at ICAS is by taking the train “Mitre line”, that runs from Retiro (terminal train station in Buenos Aires) towards Jose Leon Suarez (be aware that there are several branches of Mitre) and getting off at station Miguelete, which is almost inside the campus of the University (and then you have just a 5 minutes walk inside campus).
Concerning lodging, any hotel which is close to one the train stations of that line is very convenient. Buenos Aires is full of hotels of different qualities and prices, but for a few days we can recommend to stay in Palermo (where you find the train stations 3 de Febrero and Ministro Carranza), which offers many opportunities to enjoy the life of the city.
We have arranged a special tariff with hotel Cristóforo Colombo Palermo (http://www.hotelcc.com.ar/) U$85 single or double (per room), Taxes (21%) included . Please contact them at jmanfredi@hotelcc.com.ar stating that you are participating in an ICAS workshop (for the special offer).
We explore a simple extension of the Standard Model which incorporates a vector field in the fundamental representation of SU(2)L as the only non-standard degree of freedom. This kind of field may appear in models where a new strong sector produce the Higgs doublet as a composite state but does not break the chiral symmetry. We study the model in the presence of a discrete Z2 symmetry. As a consequence, the neutral CP-even component of the new vector field becomes a Dark Matter candidate. We constraint the values of the model parameters from unitarity bounds, h → γγ measurements, electroweak precision tests, cosmological observations and current dark matter searches.
Long-lived particles naturally appear in models where Dark Matter is produced through the freeze-in mechanism. We discuss how the LHC constraints on long-lived particles can be used to test these scenarios. In particular, using a simplified model, we illustrate how the CMS constraints on heavy stable charged particles can severely constrain the Dark Matter parameter space.
There has been a lot of activity about dark sectors in the recent years. Still, it seems like exciting ideas remain to be found and/or developed.
In this talk I will first review two recent ways of searching for a dark sector using virtual dark particles, which have been presented in arXiv:1609.01762/1705.10331/1710.00850.
Secondly, in the spirit of the workshop, I will discuss a new direction which seems certainly worth investigate: dark particle's "double fluxes" from nucleons or electrons. This might open a number of possibilities for dark sector searches at colliders.
Then I will outline a broad scenario, the "Conformal Dark Sector" (CDS), which seems to be a natural possibility to UV-complete a number of low-energy phenomenological scenarios, rendering them relatively immune to high-energy probes. The CDS scenario has characteristic predictions such as non-integer fifth forces, and deserves further investigations in many aspects including DM phenomenology, cosmology, and collider searches.
We explore the synchrotron signals generated by flavored Dark Matter candidate with mass region between 10-20 GeV annihilating into the leptonic channels $e^{+}e^{-}$ and $\mu^{+}\mu^{-}$. In these models, the interactions are skewed in flavor space, so that a dark matter particle never couples directly to the Standard Model matter fields of the same flavor, but only to the other two flavors. So, these models can bring interesting results when analyzed as an attempt to explain the Radio observations at multiple frequencies, especially in the region between 22 MHZ and 10 GHz, the well known ARCADE-2 Excess. We present the signal brightness temperature for a sort of frequencies considering the mass region of 10-20 GeV for the dark matter candidate and show that the analysed model can fit such excess.
The study of a heavy meson decaying to three lighter mesons can be described, in general, as quasi-two-body processes through the production of resonance intermediate states. To understand the dynamics of these processes, a full amplitude analysis of the corresponding Dalitz Plot (the two-dimensional representation of the decay phase space) is necessary. The most naïve way to describe it is to use the so-called Isobar Model where the total amplitude is written as a coherent sum of the individual resonance amplitudes, typically described as a product of the resonance propagator, angular functions and form factors. However, the Isobar Model turns out to be inadequate when dealing with broad scalar states and other approaches such as a model-independent partial wave analysis, K matrix, are interesting alternatives.
We show the current status of the amplitude analyses of the D decays into three mesons being pursued by the Rio Charm Group at the LHCb experiment.
Searches for CP violation in the decays of B hadrons without charmed particles in the final state offer rich opportunities to test the Standard Model. Charmless b-hadron decays are suppressed in the Standard Model by small CKM matrix elements which brings the tree amplitudes to levels comparable with loop amplitudes, and potentially New Physics amplitudes. CP violation measurements using Dalitz plot analyses in multi-body decays allow to disentangle these various contributions. We report the most recent measurements from LHCb on charmless B± meson three-body decays, considering final states containing only charged light mesons: π−π−π+, K−π−π+, K−π−K+ and K−K−K+. A study of the distribution of CP asymmetries in the B± meson decay phase space is presented.
A study of $B^+_c \rightarrow K^+K^−π^+$ decays was performed with data corresponding to 3.0$fb^{−1}$ collected by LHCb at 7 and 8 $TeV$ . Evidence for the decay $B^+_ c \rightarrow χ_{c0}(K^+K^−)π^+$ and indication of $\bar{b}c$ weak annihilation are reported. Prospects of studies of decays in other channels will be discussed.
We discuss how NP signals may show up in 3rd generation observables at the LHC.
The talk includes some of the current working areas of the La Plata group in the ATLAS experiment. The trigger is one of the essential pieces of the ATLAS detector. The e/gamma trigger performance studies to understand, improve and also provide the trigger efficiency to the precision analyses and searches for new physics are presented. Next step in the chain towards data analysis is the reconstruction of the physics objects. In particular, the electron and photon isolation are discussed. After the Higgs discovery, the interest of the group moved towards its characterisation. Spin, CP properties and cross-section studies in the Higgs decaying into photons analyses are summarised. Within the BSM theories, like NMSSM, the light Higgs boson could have different exotic decays that are being explored. Events containing photons and missing energy (plus jets or leptons) are distinctive signatures of SUSY models with gauge-mediated supersymmetry breaking. Several searches for SUSY with different final states are presented as well as prospects for discovery with the full Run 2 dataset.
Several years of LHC data taking has left us empty handed when it comes to SUSY search results. That means one of three things:
1) Nature is not supersymmetric
2) The cross-sections/masses involved are still outside the reach of the LHC.
3) Our search strategies aren't sensitive to the SUSY final states.
While the first two points will take a long time to prove, work is urgently needed to check the 3rd option. In this presentation we discuss the possibility of sensitivity gaps in our LHC analyses that might lead to fact that we have missed SUSY in our existing data set.
This talk includes some of the current working areas of the Buenos Aires group at the three levels of the ATLAS data processing chain: trigger, performance and physics analyses.
Within trigger development, the tuning of the b-jet trigger and improvement of jet trigger efficiency are discussed.
Next, the jet energy calibration and resolution are presented.
Finally, beyond Standard Model searches for extra dimensions, composite quarks, DM and FC Higgs couplings are shown.
We briefly present in this talk part of the work that the group of phenomenology at the IFLP (Conicet - Universidad de La Plata) has been carrying out over the last few years and some of the prospects for the near future. The studies to be addressed include topics in Higgs and top physics and a preliminar analysis on dark matter. In particular, we discuss lepton flavor violation in Higgs decays, pair production of heavy Higgs bosons at the LHC, CP-odd observables in the top-Higgs interaction and the building of a WIMP model that naturally evades the stringent constraints from dark matter direct detection.
I will present recent results on searching for two exotics signal at LHC: torsion and bileptons. Torsion models constitute a well known class of extended quantum gravity models. In this work, one investigates the phenomenological consequences of a torsion field interacting with top quarks at the LHC. A torsion field could appear as a new heavy state characterized by its mass and couplings to fermions. This new state would form a resonance decaying into a top anti-top pair. The latest ATLAS $t\bar t$ production results from LHC 13 TeV data are used to set limits on torsion parameters. Bileptons are bosons which have double electric charge and leptonic number. They are predicted in 331 models. We perform a study assuming different bilepton masses and calculate cross-section for different process mediated by bileptons. Combining these calculations with the latest ATLAS results at 8 TeV, we derive, for the first time, bounds on bilepton mass using LHC data. A detector simulation is also performed using the DELPHES package assuming a LHC center-of-mass energy of 13 TeV. The results of the simulation are used to obtain minimal integrated luminosities needed for discovering torsion and bileptons at LHC 13 TeV.
Supersymmetry is a very well motivated framework for physics beyond the standard model. Most of the analyses are carry out in R-parity conserving models, as for instance the Minimal Supersymmetric Standard Model (MSSM). In this context the lightest supersymmetric particle (LSP) is a good dark matter candidate. However, the fact that neutrino are massive, the absent of direct detection signals of dark matter, and the absent of missing energy signals at the LHC, motivates models without R-parity. In this context the expected signals at the LHC are more involved, for instance displaced-vertex analysis for LHC data are required.
We analyze possible detectable signals at the LHC for different LSP in R-parity breaking models, as also dark matter candidates detectable by indirect detection searches. We mainly work in the context of the mu-from-nu Supersymmetric Standard Model, or munuSSM. This model includes right-handed neutrinos in the spectrum, opening the possibility of very interesting interpretations including a relation between R-parity breaking and neutrino physics.
The São Paulo Research and Analysis Center (SPRACE) works on the analyses of the data collected by CMS. One of our main interest is the search for physics beyond standard model. In this talk I will present some of the physics studies that are being pursued at SPRACE, in particular our contribution to the search of dark matter.
In the present talk we will discuss the current status and recent advances in the calculation of the cross section for multiple Higgs production at the LHC, both in the SM as in EFT extensions of it.
We investigate the feasibility of constraining parton distribution functions in the proton through a comparison with data on semi-inclusive deep-inelastic lepton-nucleon scattering. Specifically, we reweight replicas of these distributions according to how well they reproduce recent charged kaon multiplicity measurements and analyze how this procedure optimizes the determination of the sea quark densities and improves their uncertainties. The results can help to shed new light on the long standing question on the size of the flavor and charge symmetry breaking among quarks of radiative origin. An iterative method is proposed and adopted to account for the correlation with what is assumed about the parton-to-hadron fragmentation functions in the reweighting procedure. It is shown how the fragmentation functions can be optimized simultaneously in each step of the iteration. As a first case study, we implement this method to analyze kaon production data.
We will discuss issues related to the use of perturbative QCD at relatively low energies. The theoretical problems that arise are often fundamental and touch, for instance, the very nature of the perturbative expansion. We have in mind applications to hadronic tau decays, which remains an important source of information about the strong coupling, $\alpha_s$. We will discuss renormalon singularities, scheme variations, and a novel approach to the violations of quark-hadron duality --- which go beyond perturbation theory. The impact on the precise extraction of $\alpha_s$ will be emphasised.
Inclusive jet and dijet cross-sections were measured in proton-proton collisions at a centre-of-mass energy of 13 TeV. The measurement uses a dataset with an integrated luminosity of 3.2 fb−1 with the ATLAS detector at the Large Hadron Collider. Jets are identified using the anti-kt algorithm with a radius parameter value of R=0.4. The inclusive jet cross-sections are measured double-differentially as a function of the jet transverse momentum, covering the range from 100 GeV to 3.5 TeV, and the absolute jet rapidity up to |y|=3. The double-differential dijet production cross-sections are presented as a function of the dijet mass, covering the range from 300 GeV to 9 TeV, and the half absolute rapidity separation between the two leading jets within |y|<3, y∗, up to y∗=3. Next-to-leading-order, and next-to-next-to-leading-order perturbative QCD calculations corrected for non-perturbative and electroweak effects are compared to the measured cross-sections.
We study the properties of hadrons and the structure of the QCD phase
diagram in the framework of quark models that include nonlocal interactions.
Effects of external magnetic fields are also analyzed. Model predictions are
compared with experimental data and with the results obtained through
lattice QCD calculations.
New results on the string theory dual description of deep inelastic scattering of charged leptons from hadrons are presented for strongly coupled gauge theories. These include: structure functions of glueballs, scalar and polarized vector mesons and polarized spin 1/2 hadrons. Also universal properties of string theory duals, extended Callan-Gross relations, properties of 1/Nc expansion, as well as comparison with lattice QCD results and phenomenology are discussed.
We study the behavior of strongly interacting matter under a uniform intense external magnetic field in the context of nonlocal extensions of the Polyakov–Nambu–Jona-Lasinio model. A description of the formalism is presented, considering the cases of zero and finite temperature. In particular, we analyze the effect of the magnetic field on the chiral restoration and deconfinement transitions, which are found to occur at approximately the same critical temperatures. Our results show that these models offer a natural framework to account for the phenomenon of inverse magnetic catalysis found in lattice QCD calculations.
We study the thermodynamic properties of finite systems at zero chemical potential and finite temperature, in the frame of the Polyakov loop Nambu-Jona-Lasinio model for two light and one heavy quarks. Finite size effects are considered whithin the Multiple Reflection Expansion formalism. We analyze some thermodynamic quantities including the equation of state, the interaction measure, the speed of sound, the surface tension, and the curvature energy for different system sizes, and compare our results with lattice QCD data. We find that the system undergoes a smooth crossover for all sizes. Most of the thermodynamic quantities analyzed are sensitive to finite volume effects, specially for systems with radii below $\sim 10$ fm, and for temperatures around the crossover one.
The behavior of charged pion masses in the presence of a static uniform magnetic field is studied in the framework of the two-flavor NJL model, using a magnetic field-independent regularization scheme. Analytical calculations are carried out employing the Ritus eigenfunction method, which allows us to properly take into account the presence of Schwinger phases in the quark propagators. Numerical results are obtained for definite model parameters, comparing the predictions of the model with present lattice QCD results.
The discovery of high mass Millisecond Pulsars such as J1946+3417 ($1.832
\pm 0.028 M_\odot$), J1614-2230 ($1.928 \pm 0.017 M_\odot$) and J0348+0432 ($2.01 \pm 0.04 M_\odot$) allows the
possible existence of deconfined quarks in the Neutron Stars inner core. In order to represent the matter under extremely high density conditions, we obtain a hadron-quark hybrid equation of state by considering the non linear relativistic mean-field approximation for the hadronic matter phase, and the three-flavor non-local Nambu$-$Jona-Lasinio (NJL) model,
with repulsive vector interactions, for the quark matter. The transition from hadronic to quark matter (mixed phase) is constructed by considering a soft phase transition and imposing global electric charge neutrality condition (Gibbs construction). Depending on the strength of quark vector repulsion, we find that an extended region made of a mixed phase of quarks and hadrons may exist in high-mass Neutron Stars with masses up to $2.1-2.4 M_{\odot}$. Our study also indicates that Neutron Stars with masses of around $1.4\, M_\odot$ would not contain deconfined quark matter. Recent developments and some preliminary results at finite temperature to study the stability of Proto-Neutron Stars will also be presented.
The study of neutron stars establishes a direct connection between astronomy and nuclear and particle physics, allowing a better understanding of the behavior of matter under conditions that are difficult to reach in the laboratory. Massive neutron stars provide very important constraints on high-density nuclear matter and its associated Equation of State (EoS), which is still essentially unknown. Depending on neutron star mass and rotational frequency, gravity may compress the matter in the core regions of such objects up to more than ten times the density of ordinary atomic nuclei, thus providing a high-pressure environment in which numerous subatomic particle processes are likely expected to compete with each other and phase transitions to new states of matter, foremost quark matter, may occur. In this talk, I will provide a general discussion of the properties of quark matter and explore its role for the core composition of neutron stars. Different lines of research carried out by the Astrophysics group at the FCAG will be introduced.
We study the dynamics of inhomogeneous scalar and pseudoscalar chiral order parameters within the framework of the time-dependent Ginzburg-Landau equations. We utilize a nonlocal chiral quark model to obtain the phase diagram of the model as function of temperature and baryon chemical potential and study the formation of metastable spatial domains of matter where the order parameters acquire a spatial modulation in the course their dynamical evolution. We found that, before reaching the expected equilibrium homogeneous state, both scalar and pseudoscalar chiral condensates go through long-lived metastable inhomogeneous structures.
We suggest a class of hybrid compact star equations of state which support the existence of a third family of compact stars composed of a core of two-flavor
quark matter and a shell of hadronic matter described within a relativistic meanfield model with excluded nucleon volume.
The quark matter equation of state is based on a nonlocal covariant chiral quark model with vector meson and diquark condensate.
A twofold interpolation method is realized which implements both, the density dependence of a confining bag pressure at the onset of the hadron-to-quark matter transitiona as well as the stiffening of quark matter at higher densities by a density dependent vector meson coupling.
For three parametrizations of this class of hybrid equation of state the properties of corresponding compact star sequances are presented, including mass twins of neutron and hybrid stars at 2.00, 1.39 and 1.20 $M_\odot$, respectively and the compact hybrid star (third) families. It is demonstrated that this advanced description of hybrid satr matter allows to interpret GW170817 as a merger not only of two neutron stars but also of a neutron star with a hybrid star or of two hybrid stars. The latter two scenarios are in accordance with the constraints on compactness from GW170817 when a binary neutron star merger with a too stiff hadronic equation of state would be ruled out.