Description
Posters session LHCP2019
The present approach relies on the SM chiral symmetry breaking pattern $SU(2)_L \otimes SU(2)_R \to SU(2)_{L+R}$, with the EW Goldstone bosons given in a non-linear realization and the Higgs boson described by an EW singlet field. In addition, we assume the presence of new physics heavy states around the TeV scale that do not couple to the SM fermions, only to the SM bosonic sector. However,...
The purpose of the ATLAS Roman Pot (ARP) detector is to measure protons scattered at very small angles. ARP aims to study elastic and diffractive events, exclusive production and photon induced interactions. In LHC Run 2, ARP participated in the ATLAS high-luminosity data taking. In addition, several special runs with reduced luminosity were taken. Any cross section measurement requires good...
We present the results obtained in the extraction of the main parameters of the QCD inspired approach towards the high density phase transition. Using the percolation model to define the main parameters we have extracted them for all the LHC experimental results from pp to PbPb collisions.
In ultra-relativistic heavy-ion collisions at LHC energies, a strongly interacting Quark-Gluon-Plasma (sQGP) is produced. This sQGP behaves like a perfect liquid and its hydrodynamic expansion gives rise to radial flow in heavy-ion collisions. However, similar phenomena have recently also been observed in small collision systems (pp and p$-$A). Current research therefore tries to identify the...
Precise knowledge of what a system requires is a principle that unquestionably marks the success or failure of a software development. Establishing and managing the requirements for the design of a system are fundamental aspects of software engineering. One of the main software systems in a High Energy Physics (HEP) experiment is the Detector Control System (DCS). The DCS allows the control,...
Events containing muons in the final state are an important signature for many analyses being carried out at the Large Hadron Collider (LHC), including both standard model measurements and searches for new physics. To be able to study such events, it is required to have an efficient and well-understood muon trigger. The ATLAS muon trigger consists of a hardware based system (Level 1), as well...
The members of large High Energy Physics (HEP) collaborations come from all over the world. They understand that one significant challenge in teaching experimental HEP is the current location of many potential and valuable students and young researchers. In the case of ATLAS, many of its members come from Latin-American, Middle Eastern and Sub-Saharan countries. Also, they recognise the...
The high energy and luminosity of the LHC allows to study jets and hadronically decaying tau leptons at extreme energies with the ATLAS tracking detector. These topologies lead to charged particles with an angular separation smaller than the size of the ATLAS Inner Detector sensitive elements and consequently to a reduced track reconstruction efficiency. In order to regain part of the track...
The Compact Muon Solenoid (CMS) is one of two general-purpose detectors that reconstruct the products of high energy particle interactions at the Large Hadron Collider at CERN. The silicon pixel detector is the innermost component of the CMS tracking system. It determines the trajectories of charged particles originating from the interaction region with high resolution enabling precise...
Maximally precise calibration of the CMS luminosity measurement is critical for many physics measurements. To guarantee high quality absolute calibration, a complete van der Meer scan program was carried out at the CMS experiment in 2018. The systematic uncertainty on the absolute calibration from the van der Meer scans is derived with a precision of 2.1%. The performance and stability of the...
We analyse new signals of Dark Matter (DM) at the Large Hadron Collider (LHC) in a 3-Higgs Doublet Model (3HDM) where only one doublet acquires a Vacuum Expectation Value (VEV), preserving a parity Z2. The other two doublets are inert and do not develop a VEV, leading to a dark scalar sector controlled by Z2, with the lightest CP-even dark scalar H1 being the DM candidate. This leads to the...
We discuss $Z$-production in Deep Inelastic Scattering $e + p \to e + Z + X$ using the Parton Model, in the context of the Standard Model. In contrast to the deep inelastic $ep$-scattering ($e + p \to e + X$), where $\tilde{Q}^{2}$ the transferred momentum square is unique in the case of boson production it depends upon the mechanism involved, that it is related to the EW interaction. We...
A search for the production of three massive vector bosons in $pp$ collisions
is performed using data at $\sqrt{s} = 13$ TeV recorded with the ATLAS detector
at the Large Hadron Collider in the years 2015--2017, corresponding to an
integrated luminosity of $79.8$ fb$^{-1}$. Events with two same-sign leptons
$\ell$ (electrons or muons) and at least two reconstructed jets are selected to
search...
The observation of neutral long-lived particles at the LHC would reveal physics beyond the Standard Model and could account for the many open issues in our understanding of our universe. Long-lived particle signatures are well motivated and can appear in many theoretical constructs that address the Hierarchy Problem, Dark Matter, Neutrino Masses and the Baryon Asymmetry of the Universe.
With...
Some extended models predict the existence of a new neutral massive gauge boson, identified as the $Z^\prime$ boson, together with flavor-changing neutral currents. In this theoretical framework, we estimate the intensity of couplings regarding the interaction between the $Z^\prime$ boson with the bottom and the strange quarks through the $B^0_s \rightarrow \mu^{+}\mu^{-}$ transition, which...
I will present the calculation of the h->2 gamma and h->Z gamma decays in the SM EFT at the 1-loop level. I will discuss the calculational setup including derivation of interaction vertices in physical field basis, choice of gauge fixing conditions and choice of the renormalization scheme. The final results for the Br(h->2 gamma) and Br(h->Z gamma) are given as compact semi-analytical...
We study the particle production at high transverse momentum (pT>8 GeV/c) in pp and Pb-Pb collisions at LHC energies. The characterization of the spectra is done using a power-law function and the resulting power-law exponent (n) is studied as a function ofxTfor minimum-biasppcollisions at different√s. The functional form of n as a function of xT exhibits an approximate universal behavior. ...
During the ongoing Long Shutdown 2 the accelerator complex at CERN will significantly improve
the performance of the collider by boosting the heavy-ion collision parameters of Run 3 and 4 to well beyond the specifications of the current ALICE setup. For instance, the Pb-Pb instantaneous luminosity during Run 3 will increase by a factor of 5 to 6 and the minimum-bias (MB) Pb-Pb interaction...
We perform an effective field theory analysis of the τ−→π−π0ντ decays, that includes the most general interactions between Standard Model fields up to dimension six, assuming left-handed neutrinos. We constrain as much as possible the necessary Standard Model hadronic input using chiral symmetry, dispersion relations, data and asymptotic QCD properties. As a result, we set precise (competitive...
We analyze the τ−→(Kπ)−ντ decays within an effective field theory description of heavy new physics (NP) modifying the SM left-handed weak charged current and include refined SM input (with controlled uncertainties) for the participant meson form factors exploiting chiral symmetry, dispersion relations and data. We include the leading dimension six operators and work at linear order in the...
MoEDAL (Monopole and Exotics Detector at the LHC) is the 7th experi-
ment, specifically dedicated to investigating beyond the Standard Model sce-
narios by searching for highly ionizing particles, such as magnetic monopoles
or massive pseudo-stable charged particles and multiply electrically charged
particles as messengers of new physics. Sharing the same interaction point as
the LHCb...
After the discovery of a light Higgs boson, the scattering of electroweak vector bosons (VBS) is even more an eminent search channel for new physics due to the intricate cancellations between gauge and Higgs amplitudes. We will discuss the most general model-independent parameterization for new physics in terms of Standard Model Effective Field Theory (SMEFT), and detail the limitations of...
Since 2014 several outreach activities have been performed together with IPPOG, Quarknet and DESY programs. We started in Mexico city in 2014 with a workshop with high school teachers and later working with their students. This year the activities have reached five cities in five different Mexican states and are continuing to grow. In 2018 a collaboration with the University of Notre Dame...
The ATLAS experiment has a rich physics program of Standard Model measurements and searches for physics Beyond the Standard Model involving tau leptons. Most of these analyses depend on an efficient tau-lepton trigger that can cope with the overwhelming background from multi-jet events produced in proton-proton collisions at the Large Hadron Collider. The ATLAS trigger system is composed of...
We will present the first results and the physics prospects from the CMS Precision Proton Spectrometers namely the observation of exclusive dileptons at high mass, and the search for quartic anomalous couplings and axion like particles at high masses at the LHC in the CMS collaboration.
Several High Energy Physics experiments are adopting Gaseous Electron Multipliers (GEMs) in substitution for the Multi-Wire Proportional Counters (MWPC) either in upgrade plans or in the design stage. The ALICE experiment, for instance, is passing through upgrades that, among other goals, aim the replacement of the MWPC at the readout planes of its Time Projection Chamber (TPC) by a stack of...
Poster abstract: Precision measurements of electroweak boson production in $pp$ collisions are considered benchmark tests of the Standard Model. In particular, they provide
verification for predictions of the electroweak theory and quantum chromodynamics (QCD). The rapidity of electroweak bosons produced in $pp$ collisions is strongly
correlated with the initial quark dynamics. Therefore,...
Prospects for the study of Higgs boson pair (HH) production in the HH→bb4l (l = e, µ) channel are studied in the context of the High-Luminosity LHC. The analysis is performed using a parametric simulation of the Phase-2 CMS detector response provided by the Delphes software and assuming an average of 200 proton-proton collisions per bunch crossing at a center-of-mass energy of 14 TeV. Assuming...
We investigate the energy dependence of the photo-production cross-section of vector mesons $J/\Psi$ and $\Upsilon$, which has been measured by both HERA experiments H1 and ZEUS in electron-proton collisions and by LHC experiments ALICE, CMS and LHCb in ultra-peripheral proton-proton and ultra-peripheral proton-lead collisions. Our study uses 2 particular fits of inclusive unintegrated gluon...
The Phase-II upgrade plan for the ATLAS Tile Calorimeter facing the High Luminosity LHC (HL-LHC) era includes approximately 1024 radiation-tolerant readout link and control boards (Daughterboards) that will provide full granularity digital data to a fully-digital trigger system off-detector through multi-Gbps optic fibers. The Daughterboard design minimises radiation-induced errors and...
In this poster we will present the recent results from the NA62 experiment at CERN.
NA62 is an experiment dedicated to the study of rare kaon decays. Important results such as the Brnching Ratio of $K^+ \to \pi^+ \nu \bar{\nu}$, the search for heavy neutral leptons and the serach for lepton number violating kaon decays will be shown.
The ability to reconstruct almost-straight tracks with good momentum resolution is closely tided to maintaining a good understanding of the ATLAS tracking detectors' alignment and the related uncertainties. Moreover, an optimal selection of muon candidates with TeV-scale transverse momentum (pT) is a critical factor in determining the sensitivity of analyses looking for new high-mass...
For precise calibration of luminosity measurements, it is necessary to understand nonlinear effects which affect the single bunch instantaneous luminosity (SBIL) measured by a luminometer. The CMS BRIL group uses data from the hadronic forward (HF) calorimeter, the Pixel Luminosity Telescope (PLT), and the Fast Beam Conditions Monitor (BCM1F) to measure the luminosity. A "mu scan" is a beam...
After data taking in p-p collisions at $\sqrt{s}$ = 13 TeV, the LHCf collaboration sustained a strong analysis effort in order to precisely measure neutral particle production in the very forward region at high energy. These results are expected to have a strong impact on the tuning of phenomenological models used to describe soft hadronic processes. In this contribution, we report about the...
One of the key signatures of collectivity in heavy-ion collisions is the appearance of a ridge structure over wide pseudorapidity interval. In this work we explore the contributions from the geometry fluctuations in the initial-state in pp collisions to the ridge structure, estimated from low to high density. Effects show to be relevant for small collision systems unlike in heavy-ion...
Several new physics models predict the existence of neutral particles with macroscopic life-times that decay to pairs of leptons and light hadrons with a jet-like structure (lepton-jets). These particles, decaying outside of the interaction region, will give rise to striking signatures in the detectors at the LHC. These can be detected through numerous unconventional signatures: long...
Supersymmetry is one of the most promising theories which extend the Standard Model in order to solve the dark matter and the hierarchy problem. The squark and gluinos are one of primary targets in supersymmetry searches, as the pair production has large cross section at the LHC via the strong interaction. This poster presents recent ATLAS results from searches for gluinos and squarks in final...
The existence of pseudoscalars weakly coupled to particles from the Standard Model of particle physics, known as axion-like particles (ALP), would induce anomalous scattering of light-by-light. Searching for these particles relying only on their coupling to the electromagnetic field is challenging. This process can be probed at the Large Hadron Collider (LHC) in production of photon pairs in...
The High-Luminosity Large Hadron Collider (HL-LHC) upgrade aims to increase its luminosity by a factor of 5 beyond the
LHC's design value and the integrated luminosity by a factor of 10, increasing the potential for discoveries after 2025.
The increased collision rate of particles will be a challenge for the CMS systems as higher levels of radiation could
degrade them and affect their...
By using the string percolation framework we study the shear and bulk viscosity over entropy ratio in addition to studying the mixed effect of the two viscosities in high multiplicity events in $pPb$ and $pp$ collisions at the current LHC energies, where evidence on collective like effects has been found recently on data. Evidence of the formation of a strongly interacting medium similar to...
Fluctuations may arise from initial state fluctuations and thermodynamical fluctuations, as temperature fluctuations which is an important quantity that allows to probe the fluctuations at early stages of the reaction and to understand QCD transition order for small collision systems. A large number of particles produced at high multiplicity events on pp collisions where signals of...
The behavior of the underlying event density dependence on the leading particle transverse momentum has been widely reported and used to tune MC generators to the data of pp collisions. However to our knowledge all the studies have been done, both in data and generators for minimum bias data. We present a work that investigates the behavior of the underlying event in function of the...
ATLAS electron and photon triggers covering transverse energies from 5 GeV to several TeV are essential to record signals for a wide variety of physics: from Standard Model processes to searches for new phenomena in both proton-proton and heavy ion collisions. To cope with ever-increasing luminosity and more challenging pile-up conditions at the LHC, the trigger selections needed to be...
We revisit the rare decay of the Higgs boson into two different quarks at the one-loop level in the Standard Model. We implement the GIM mechanism in a strict manner, by performing meticulous Taylor expansions of the amplitude's form factors, in order to get rid of spurious terms. We predict Br$(H\to uc)$=$1.63\times10^{-18}$, Br$(H\to ds)$=$9.07\times10^{-15}$, Br$(H\to...
We study the ratio of the pion, kaon and proton particle production on high multiplicity pp collisions at LHC energies, over the transverse momentum spectra corresponding to the energy density of a dilute system in the framework of clustering of color sources to describe the suppression due to initial state effects. Results show suppression for all the multiplicity classes with the strongest...
The so called rho-pi puzzle has defied every theoretical approach, and it consists in understanding why higher-mass intermediate states are suppressed in favor of rho-pi dynamics. The study of known decays of the psi meson can shed light in solving this puzzle. In several sources it has been introduced the use of a form factor for the meson meson meson vertices due to the internal...
ALFA detector is part of the ATLAS Roman Pot detector dedicated to measure protons scattered at very small angles. ALFA aims to study elastic and diffractive events in special runs with reduced luminosity and optimized beam optics. Precision of the measurement depends on the correct positioning of the ALFA detector with respect to the actual beam position. For this purpose track-based...
The performance of several trigger counters based on plastic scintillators with silicon photomultiplier readout is investigated with cosmic rays. Efficiency and time resolution are measured using digital waveform analysis. The obtained results are relevant for trigger subsystems of Baryonic Matter at the Nuclotron (BM@N) and Multi-Purpose Detector (MPD) at the NICA heavy-ion collider. The...
At the LHC, the number of inelastic proton-proton collisions per second is related to the luminosity. Track counting is one of the methods for luminosity measurement in the ATLAS experiment. It is done by counting the number of charged-particle tracks reconstructed in the inner detector in unbiased triggers, where the number of tracks scales with the number of interactions. Therefore, as long...
The High Luminosity LHC (HL-LHC) aims to increase the LHC data-set by an order of magnitude in order to increase its potential for discoveries. The high pileup at the HL-LHC presents a highly challenging environment to particle detectors. To cope with this, the current Inner Detector of the ATLAS experiment will be replaced with a new all-silicon Inner Tracker (ITk). In this poster the...
The High-Luminosity LHC (HL-LHC) is planned to start the operation in 2026 with an instantaneous luminosity of 7.5 x 1034 cm-2s-1. In order to cope with the event rate higher than that of LHC, the trigger and readout electronics of ATLAS Thin Gap Chamber (TGC) will need to be replaced. All hit data will be transferred from the frontend to the backend boards and exploited by an advanced...
