Particle physics is a field which is full of striking visuals: from Feynman diagrams to event displays, there is no shortage of colourful high-contrast shapes and designs to capture the imagination. Can these visuals be used to reach out to budding scientists from their very earliest days? This talk will describe the development of the "Particle Physics for Babies" children's book, a concept...
Deep Learning (DL) is one of the most popular Machine Learning models in the High Energy Physics (HEP) community and has been applied to solve numerous problems for decades. The ability of the DL model to learn unique patterns and correlations from data to map highly complex non-linear functions is a matter of interest. Such features of the DL model could be used to explore the hidden physics...
The ATLAS Visitor Centre at CERN is a guided exhibition space that has been welcoming visitors from around the world since 2009. In a recent effort, ATLAS has reinvented the whole exhibition, replacing the original installation with a completely new exhibition. This contribution will highlight the basic concept behind the new exhibition, introduce its main components along with details on...
SND@LHC is a compact and stand-alone experiment to perform measurements with neutrinos produced at the LHC in a hitherto unexplored pseudo-rapidity region of 7.2 < 𝜂 < 8.6, complementary to all the other experiments at the LHC. The experiment is located 480 m downstream of IP1 in the unused TI18 tunnel. The detector is composed of a hybrid system based on an 800 kg target mass of tungsten...
We present a reinterpretation study of existing results from the CMS Collaboration, specifically, searches for light BSM Higgs pairs produced in the chain decay $pp\to H_{\rm SM}\to hh(AA)$ into a variety of final states, in the context of the CP-conserving 2-Higgs Doublet Model (2HDM) Type-I. Through this, we test the LHC sensitivity to a possible new signature, $pp\to H_{SM}\to ZA\to ZZ h$,...
The simulation is being used to produce artificial events for physics analyses. In the ATLAS experiment at LHC CERN, Geneva, Switzerland, simulation is carried out on the GEANT4 platform. The GEANT4 uses geometry descriptions as an input for the modelling of the propagation of the particles in the material. Adding CATIA (Computer-Aided Three-dimensional Interactive Application) CAD application...
The Liquid Argon Calorimeters are employed by ATLAS for all electromagnetic calorimetry in the pseudo-rapidity region |η| < 3.2, and for hadronic and forward calorimetry in the region from |η| = 1.5 to |η| = 4.9. They also provide inputs to the first level of the ATLAS trigger. After successful period of data taking during the LHC Run-2 between 2015 and 2018 the ATLAS detector entered into the...
The ATLAS Open Data project aims to deliver open-access resources for education and outreach in High Energy Physics using real data recorded by the ATLAS detector. The Open Data release so far has resulted in the release of a substantial amount of data from 8 TeV and 13 TeV collisions in an easily-accessible format and supported by dedicated software and documentation to allow its fruitful use...
ALFA and AFP detectors are being prepared to take data during Run 3. ALFA underwent refurbishment whereas AFP, among other upgrades, was equipped with new solution for Time-of-Flight system, so-called Out-of-Vacuum solution. AFP Silicon Tracker is equipped with new modules and ToF, after various testbeams, seems to achieved desired resolution with high efficiency.
The ATLAS Trigger in Run 3 is expected to record on average around 1.7 kHz of primary 13.6 TeV physics data, along with a substantial additional rate of delayed data (to be reconstructed at a later date) and trigger-level-analysis data, surpassing the instantaneous data volumes collected during Run 2.
Events will be selected based on physics signatures such as the presence of energetic...
The Virtual Visit service run by the ATLAS Collaboration has been active since 2010. The ATLAS Collaboration has used this popular and effective method to bring the excitement of scientific exploration and discovery into classrooms and other public places around the world. The programme, which uses a combination of video conferencing, webcasts, and video recording to communicate with remote...
We have explored the effect of weak magnetic field on the transport of charge and heat in hot and dense QCD matter by calculating their response functions, such as electrical conductivity ($\sigma_{\rm el}$), Hall conductivity ($\sigma_{\rm H}$), thermal conductivity ($\kappa_0$) and Hall-type thermal conductivity ($\kappa_1$) in kinetic theory approach. The interactions among partons have...
In this work, we derive lower mass bounds on the $Z^\prime$ gauge boson based on the dilepton data from LHC with 13 TeV of center-of-mass energy, and forecast the sensitivity of the High-Luminosity-LHC with $L=3000 fb^{-1}$, the High-Energy LHC with $\sqrt{s}=27$~TeV, and also at the Future Circular Collider with $\sqrt{s}=100$~TeV. We take into account the presence of exotic and invisible...
In current and future high-energy physics experiments, the sensitivity of selection-based analysis will increasingly depend on the choice of the set of high-level features determined for each collision. The complexity of event reconstruction algorithms has escalated in the last decade, and thousands of parameters are available for analysts. Deep Learning approaches are widely used to improve...
In this study, we explore the effects of CP-violating anomalous interactions of the top-quark through the semileptonic decay modes of the top-quark arising due to pair-production of tt̄ at the Large Hadron Collider. Predictions on the LHC sensitivities of the coupling strength to such CP-violating interactions would be discussed for the 13 TeV LHC data and for the future hadron collider with...
In the Standard Model, CP violation in the Electroweak sector is parametrized by the Jarlskog Invariant. This is the order parameter of CP-violation, in the sense that it vanishes iff CP is conserved. When higher dimensional operators are allowed, and the Standard Model Effective Field Theory is constructed, numerous new sources for CP violation can appear. However, the description of CP...
In recent years, crowdfunding platforms have gained popularity as a way to raise funds for various endeavors. This poster discusses the use of crowdfunding as a non-traditional way to finance physics outreach projects. Such tools can provide much needed flexibility to projects and serve as a platform to spread the word about your project. The poster is based on first-hand experience using...
In this paper, we study the prospect of ECAL barrel timing to develop triggers dedicated to long-lived particles decaying to jets at the level-1 of HL-LHC. We construct over 20 timing-based variables, and identify three of them which have better performances and are robust against increasing PU. We estimate the QCD prompt jet background rates accurately using the ``stitching'' procedure for...
The strong force is the least known fundamental force of nature, and the effort of precisely measuring its coupling constant has a long history of at least 30 years. This contribution presents a new experimental method for determining the strong-coupling constant from the Sudakov region of the transverse-momentum distribution of Z bosons produced in hadron collisions through the Drell-Yan...
The increase of the particle flux (pile-up) with luminosities of L ≃ 7.5 × 10^34cm^−2s^−1 is one of the main experimental challenges for the HL-LHC physics program. A powerful new way to mitigate the effects of pileup is to use high-precision timing information to distinguish between collisions occurring close in space but well-separated in time. A High-Granularity Timing Detector, based on...
A new era of hadron collisions will start around 2028 with the High-Luminosity LHC, that will allow to collect ten times more data that what has been collected so far at the LHC. This is possible thanks to a higher instantaneous luminosity and higher number of collisions per bunch crossing.
To meet the new trigger and data acquisition requirements and withstand the high expected radiation...
The Low Gain Avalanche Detector (LGAD) technology is proposed for the ATLAS High Granularity Timing Detector (HGTD) towards the High-Luminosity Large Hadron Collider (HL-LHC). The USTC-IME v2.0 and v2.1 LGAD sensors are designed by the University of Science and Technology of China (USTC) and fabricated by the Institute of Microelectronics of the Chinese Academy of Science (IME, CAS). Various...
We explore the ability of a recently proposed jet substructure technique, Dynamical Grooming, to pin down the properties of the Quark-Gluon Plasma formed in ultra-relativistic heavy-ion collisions. In particular, we compute, both analytically and via Monte-Carlo simulations, the opening angle $\theta_g$ of the hardest splitting in the jet as defined by Dynamical Grooming. Our calculation,...
The ATLAS Collaboration has developed a variety of printables for education and outreach activities. We present two ATLAS Colouring Books, the ATLAS Fact Sheets, the ATLAS Physics Cheat Sheets, and ATLAS Activity Sheets. These materials are intended to cover key topics of the work done by the ATLAS Collaboration and the physics behind the experiment for a broad audience of all ages and levels...
Color-reconnection (CR) mechanism used in PYTHIA8 has been reported to describe collective-like effects in small systems, such as mass-dependent growth in $\langle {\textit{p}_{\rm T}} \rangle$ as a function of multiplicity, enhanced baryon production over meson at intermediate ${\textit{p}_{\rm T}}$, etc., similar to those observed in heavy-ion collisions. Color-reconnection (CR) and...
This submission describes revised plans for Event Filter Tracking in the upgrade of the ATLAS Trigger and Data Acquisition system for the high pileup environment of the High-Luminosity Large Hadron Collider (HL-LHC). The new Event Filter Tracking system is a flexible, heterogeneous commercial system consisting of CPU cores and possibly accelerators (e.g., FPGAs or GPUs) to perform the...
Short-lived resonances can probe strongly interacting matter produced in high-energy heavy-ion collisions. In particular, K*(892)$^{\mathbf{\pm}}$ is important because of its very short lifetime (around 4 fm/c), comparable to the partonic plasma phase. Also, its short lifetime can be used to study the rescattering and regeneration effects in the hadronic phase. An event shape observable like...
The ATLAS Collaboration consists of more than 5000 members, from over 100 different countries. Regional, age and gender demographics of the collaboration are presented, including the time evolution over the lifetime of the experiment. In particular, the relative fraction of women is discussed, including their share of contributions, recognition and positions of responsibility, including...
Relativistic heavy-ion beams at the LHC are accompanied by a large flux of equivalent photons, leading to multiple photon-induced processes. One of the most basic processes, originating from the photon-photon interactions, is the exclusive production of lepton pairs. This poster presents new measurements of exclusive dielectron and dimuon production performed by the ATLAS Collaboration, using...
Development of a new framework for the derivation of order-by-order hydrodynamics from the Boltzmann equation is necessary as the widely used Anderson-Witting formalism leads to violation of fundamental conservation laws when the relaxation-time depends on particle energy, or in a hydrodynamic frame other than the Landau frame. We generalize an existing framework for the consistent derivation...
Heavy-quark symmetry (HQS), despite being approximate, allows to relate dynamically many hadron systems. In the HQS-limit heavy mesons and doubly-heavy baryons are very similar as their dynamics is determined by a light quark moving in a color field of a static source. As in the meson case, matrix elements of non-local interpolation currents between the baryon state and vacuum are determined...
The applicability of hydrodynamics to study the space-time evolution of hadronic matter produced in relativistic heavy-ion collisions is one of the outstanding issues. The hadronic matter may be produced initially in the hadronic phase or may appear after a quark-gluon plasma phase produced initially revert to hadronic matter through a phase transition. The Knudsen number ($Kn$) can be used...
The rich physics program at the high luminosity LHC (HL-LHC) requires all final state particles to be reconstructed with good accuracy. However, it also poses formidable challenge of dealing with very high pile up. Different identification algorithms need to be upgraded along with the detectors to improve the overall event reconstruction in such a hostile collision environment. The new timing...
A study is performed on the possible Bose-Einstein Condensation (BEC) of pions in proton-proton (pp) collisions at √s = 7 TeV at the Large Hadron Collider. To have a better and clear understanding, the results of pp systems have been contrasted with the systems produced in Pb-Pb collisions. We studied the temperature and final state multiplicity dependence of the number of particles in the...
Femtoscopy is a technique that can be used to measure the space-time characteristics of the particle-emitting source created in heavy-ion collisions using momentum correlations between two particles. In this report, the two-pion and two-kaon femtoscopic correlations for Pb$--$Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV within the framework of (3+1)D viscous hydrodynamics combined with...
The implementation of a web portal dedicated to Higgs boson research is presented. A database is created with more than 1000 relevant articles using CERN Document Server API and web scraping methods. The database is automatically updated when new results on the Higgs boson become available. Using natural language processing, the articles are categorised according to properties of the Higgs...
In preparation for LHC Run 3, ATLAS completed a major effort to improve the track reconstruction performance for prompt and long-lived particles. Resource consumption was halved while expanding the charged-particle reconstruction capacity. Large-radius track (LRT) reconstruction, targeting long-lived particles (LLP), was optimized to run in all events expanding the potential phase-space of LLP...
We estimate in medium properties of axion i.e., its mass and self-coupling within a three flavor Polyakov loop extended Nambu–Jona-Lasinio (PNJL) model with Kobayashi-Maskawa-t’Hooft determinant interaction. We also estimate the topological susceptibility of strong interaction within the same model. It is observed that (statistical) confinement effects simulated by Polyakov loop potential play...
Despite modern particle physics being an international endeavour, the vast majority of its educational material is only published in English. By making material available in other languages, physicists can make in-roads with new audiences – especially those very young or very old – in their home countries. The ATLAS Collaboration has published colouring books, a teaching guide, activity...
Non-central heavy-ion collisions at ultra-relativistic energies are unique in generating magnetic fields of the most significant strength in the laboratory. The fields produced at the early stages of the collision could affect the properties of Quantum Chromodynamics (QCD) matter formed in the heavy-ion collisions. Moreover, this transient magnetic field can also affect the thermodynamic and...
The search for the QCD critical point (CP), and the study of quark-hadron phase transition (and vice-versa), at finite baryon density and high temperature, is the main task in contemporary relativistic heavy-ion collision experiments. Fluctuation analysis with global and local measures is the basic tool to achieve this goal. Local density fluctuations are directly related to the critical...
I introduce quantum mechanics on an intrinsic configuration space for baryons, the Lie group U(3), which carries the three gauge groups of the standard model of particle physics as subgroups SU(3), SU(2) and U(1). The strong and electroweak interactions become related via the Higgs mechanism. I namely settle the electroweak energy scale by the neutron to proton decay where both sectors are...
We investigate the prospect of searching for new physics via the novel signature of same-sign diboson + ${E\!\!/}_{T}$ at current and future LHC. We study three new physics models: (i) natural SUSY models, (ii) type-III seesaw model and (iii) type-II seesaw/Georgi-Machacek model. In the first two class of models, this signature arises due to the presence of a singly-charged particle which has...
We perform a sensitivity study of an unbinned angular analysis of the $B\to D^*(D\pi)\ell\nu_\ell$ decay, including the contributions from the right-handed vector current. We show that the angular observable can constrain very strongly the right-handed vector current without the intervention of the yet unsolved $V_{cb}$ puzzle.
In this work, we have modified a scenario, originally proposed by Grimus and
Lavoura, in order to obtain maximal values for atmospheric mixing angle and $CP$ violating Dirac phase of the lepton sector. To achieve this, we have employed $CP$ and some discrete symmetries in a type II seesaw model. In order to make predictions about neutrino mass ordering and the smallness of the reactor angle,...
A significant challenge in the tagging of boosted objects via machine-learning technology is the prohibitive computational cost associated with training sophisticated models. Nevertheless, the universality of QCD suggests that a large amount of the information learnt in the training is common to different physical signals and experimental setups. In this article, we explore the use of transfer...
Light nuclei production is a hot research topic in heavy-ion collision at RHIC-BES. The observed non-monotonic behavior with the colliding energies[1,2] was declared to be related to the critical point of the QCD phase diagram[3,4]. In this talk, we focus on investigating the light nuclei production with and without critical fluctuations within the framework of the coalescence model.
In the...
We analyze NMSSM scenarios containing a singlino LSP dark matter. By systematically considering several NLSP compositions, we identify and classify regions of parameter space where NLSP exhibits a long lifetime due to suppressed couplings and leads to a displaced vertex signature at the colliders. We furthermore construct viable production and decay processes at the HL-LHC to search for such...
Long-lived particles represent a well motivated approach for beyond-Standard Model (SM) physics searches. An interesting scenario is the one in which light vector mediators (dark photons), weakly coupled to the SM photon, can be produced by an exotic decay of the SM Higgs boson and decay back to SM particles after travelling a macroscopic distance. This study presents a search for light,...
We study the pair production of the long-lived mediator particles from the decay of the SM Higgs boson and their subsequent decay into standard model particles. We compute the projected sensitivity, both model-independently and with a minimal model, of using the muon spectrometer of the CMS detector at the HL-LHC experiment for ggF, VBF, and Vh production modes of the Higgs boson and various...
The CMS experiment is a general-purpose detector installed in Large Hadron collider. During the High Luminosity LHC (HL-LHC) phase, it expects 10 times higher luminosity than actual LHC operation regime. Forward region of Muon system of CMS will be equipped with 3 additional triple GEM based muon stations. ME0 is the innermost layer of this tree stations which will be installed right behind...
A measurement of the inclusive jet production in proton-proton collisions at the LHC at $\sqrt{s}=13$ TeV is presented. The double-differential cross sections are measured as a function of the jet transverse momentum $p_\mathrm{T}$ and the absolute jet rapidity $\|y|$. The anti-$k_\mathrm{T}$ clustering algorithm is used with distance parameter of 0.4 (0.7) in a phase space region with jet...
Two-particle normalized cumulants of particle number correlations ($R_{2}$) and transverse momentum correlations ($P_{2}$) measured as a function of relative pseudorapidity and azimuthal angle difference $(\Delta\eta, \Delta\varphi)$ provide key information about particle production mechanism, diffusivity, charge and momentum conservation in high-energy collisions. To complement the recent...
Differential cross sections for top quark pair ($t\bar{t}$) production are measured in proton-proton collisions at a centre-of-mass energy of 13 TeV using a sample of events containing two oppositely charged leptons. The data were recorded with the CMS detector at the LHC and correspond to an integrated luminosity of 138 fb^{−1}. Differential cross sections are measured as functions of...
Heavy-quark production in nuclear collisions is an important tool to access the properties and evolution of a deconfined state of nuclear matter known as quark-gluon plasma. Studies of these probes in pp collisions, besides serving as a reference process, represent a powerful tool for testing various aspects of QCD. An analysis technique that was little explored until now at LHC energies is...
lectrons constitute an essential component of final states from the leptonic decay channels of W and Z bosons. Their reconstruction and identification are especially challenging in heavy-ion collisions due to high detector occupancy. Therefore, the evaluation of electron performance is crucial for precision measurements of properties of quark-gluon plasma produced in heavy-ion collisions at...
The identification of jets containing b-hadrons, b-tagging, plays an important role in many physics analyses in ATLAS. Several different machine learning algorithms have been deployed for the purpose of b-tagging. These tagging algorithms are trained using Monte-Carlo simulation samples, as such their performance in data must be measured. The b-tagging efficiencies (epsilon_b) have been...
The LHC forward (LHCf) is a unique experiment designed on purpose to measure neutral particle production spectra in the forward region to provide high energy data for the tuning of the hadronic interaction models used by ground-based cosmic rays experiments, thanks to the excellent performance of this experimental apparatus, composed by two sampling calorimeters, called Arm1 and Arm2, located...
A measurement of the top quark pole mass in events where the top quark-antiquark pair is produced in association with one additional jet is presented. This analysis is performed using proton-proton collision data at 13 TeV collected by the CMS experiment at the CERN LHC in 2016, corresponding to a total integrated luminosity of 36.3 fb${-1}$. Events with two opposite charge leptons in the...
Quarkonia are bound states of heavy quark--antiquark pairs. Due to their large mass, heavy quarks production mechanism takes place at hard scales of QCD, while the formation of the bound states involves soft QCD scales. Quarkonia are therefore sensitive to both perturbative and non-perturbative aspects of QCD.
In addition, their measurement in p--Pb collisions provides information on cold...
We present a prospect study on di-Higgs production in the HH to bbyy decay channel with the ATLAS experiment at the High Luminosity LHC (HL-LHC). The results are obtained by extrapolating the results from the Run 2 measurement, with 139/fb of data at a center-of-mass energy of 13 TeV, to the conditions expected at the HL-LHC. While there is no sign of di-Higgs production with the current LHC...
Quantum Chromodynamics predicts the existence of dense and hot nuclear matter which is described in terms of a deconfined medium of quarks and gluons, known as quark-gluon plasma (QGP). High energy density and temperature can be reached by colliding heavy-ions at ultra-relativistic energies, enabling the study of the QGP in the laboratory. The ALICE detector at the LHC was designed to study...
In this work, we introduce both gluon and quark degrees of freedom for describing the partonic cascades inside the medium. We present numerical solutions for the set of coupled evolution equations with splitting kernels calculated for the static, exponential and Bjorken expanding media to arrive at medium-modified parton spectra for quark and gluon initiated jets respectively. We discuss novel...
Measurements of jet fragmentation and jet properties in pp collisions provide a test of perturbative quantum chromodynamics (pQCD) and form a baseline for similar measurements in heavy ion (A-A) collisions. In addition, jet measurements in p-A collisions are sensitive to cold nuclear matter effects. Recent studies of high-multiplicity final states of small collision systems exhibit signatures...
Hadronic resonances are effective tools for studying the hadronic phase in ultra-relativistic heavy-ion collisions. In fact, their lifetime is comparable to the hadronic phase and resonances are sensitive to the hadronic phase effects such as rescattering and regeneration processes which might affect the resonance yields and shape of the transverse momentum spectra. $\Lambda(1520)$ has a...
The ATLAS and CMS experiments have an ambitious search program for charged Higgs bosons. The two main searches for $H^\pm$ at the LHC have traditionally been performed in the $\tau \nu$ and $t b$ decay channels, as they provide the opportunity to probe complementary regions of the Minimal SuperSymmetric Model (MSSM) parameter space. Charged Higgs bosons may decay also to light quarks, $H^\pm...
The identification of jets containing b-hadrons (b-jets) is essential to many aspects of the ATLAS physics programme. Multivariate algorithms responsible for establishing the jet's flavour are developed by the ATLAS Collaboration, exploiting the distinct properties and correlations of charged particle tracks within the jet and reconstructed secondary vertices. The higher pileup conditions and...
PYTHIA8 simulates a number of physics aspects by implementing several models along with theory, these models have many free parameters that need to be tweaked for the best description of data. In this study, we use PYTHIS8.2 for the simulation of Multiparton Interactions using different PDF sets from LAHPDF6. Altogether five parameters were selected for the final tune depending on their...
No analysis in ATLAS or CMS has so far searched for FCNC decays of top quarks into a new scalar (X) in a broad mass range probing branching ratios below $10^{-3}$. In the case of the Higgs boson, branching ratios $t\to Hu/c$ are predicted within the SM to be of about $O(10^{-17})/O(10^{-15})$. Several beyond-SM theoretical models predict new particles and enhanced branching ratios. In...
Heavy quarks are considered excellent probes to study the properties of the state of matter where quarks and gluons are deconfined, known as quark-gluon plasma (QGP). The QGP is expected to be formed in ultrarelativistic nuclear collisions. Non-prompt J/$\psi$ measurements are important to investigate the parton energy loss in the hot medium and its quark mass dependence, as they provide...
We present two modules as part of the Czech Particle Physics Project (CPPP). These are intended as learning tools in masterclasses aimed at high-school students (aged 15 to 18). The first module is dedicated to the detection of an Axion-Like-Particle (ALP) using the ATLAS Forward Proton (AFP) detector. The second module focuses on the reconstruction of the Higgs boson mass using the Higgs...
Proton decay is a baryon number violating process and hence is forbidden in the Standard Model (SM). Baryon number violation is expected to be an important criteria to explain the matter anti-matter asymmetry of the universe. Any detection of the proton decay will serve as a direct evidence of physics beyond the SM. In SMEFT, proton decay is possible via baryon number violating dimension six...
We investigate the full electro-weak one-loop radiative correction to the $e^+e^- \to H^+H^-$ within the Inert Higgs Doublet Model (IHDM), at the future Higgs factory such as the ILC, CLIC, CEPC. After taken account of the theoretical and experimental constraints such as LEP, LHC and Dark matter constraints. The calculations are performed using FeynArts/FormCalc to compute the one-loop weak...
The Tile Calorimeter (TileCal) is a sampling hadronic calorimeter covering the central region of the ATLAS experiment, with steel as absorber and plastic scintillators as active medium. The scintillators are read-out by the wavelength shifting fibres coupled to the photomultiplier tubes (PMTs). The analogue signals from the PMTs are amplified, shaped, digitized by sampling the signal every 25...
Since its installation in 2016, AFP took data during standard (low-beta, high-µ) and special (low-beta, low-µ) LHC fills. Performance of tracking and time-of-flight systems as well as studies of trigger performance and detector alignment will be discussed.
The expected increase in particle flux in the high-luminosity phase of the LHC (HL-LHC), with an instantaneous luminosity that can reach L ≈ 7.5 × 10^34cm^−2s^−1, will have a significant impact on the pile-upwith potentially 200 interactions per bunch crossing. The performances of electrons and photons, as well as those of jets and missing transverse energy, will be strongly degraded in the...
Reconstructing the type and energy of isolated pions from the ATLAS calorimeters is a key step in the hadronic reconstruction. The baseline methods for local hadronic calibration were optimized early in the lifetime of the ATLAS experiment. Recently, image-based deep learning techniques demonstrated significant improvements over the performance over these traditional techniques. We present an...
The MIP Timing Detector (MTD) is a new sub-detector planned for the Compact Muon Solenoid (CMS) experiment at CERN, aimed at maintaining the excellent particle identification and reconstruction efficiency of the CMS detector during the High Luminosity LHC (HL-LHC) era. The MTD will provide new and unique capabilities to CMS by measuring the time-of-arrival of minimum ionizing particles with a...
Extensive studies at the Large Hadron Collider (LHC), CERN and Relativistic Heavy Ion Collider (RHIC), Brookhaven National Laboratory (BNL) on heavy-ion collisions such as Pb+Pb and Au+Au collisions have helped us understand the existence of Quark-Gluon Plasma (QGP) and study its properties in detail. Recent QGP-like signatures were observed in high-multiplicity proton+proton (pp) collisions....
PYTHIA is a highly successful and well-established Monte Carlo event generator, different options of selected physics models offered by PYTHIA8 are investigated using best fit to the Minimum Bias published data by ATLAS. These models include a new scenario for Multiparton Interactions (MPI), impact parameter dependence, and color reconnection choices. MPI should be switched on to get...
Within the Standard Model (SM) the Higgs boson is predicted to be a scalar particle ($J^{CP}=0^{++})$. However, simple extensions to the SM, such as the Higgs characterisation model, allow for CP-odd couplings of the Higgs to other particles. Such modifications to the coupling can be probed by studying the Yukawa interaction of the Higgs with fermions. The modification the Lagrangian for the...
The measurement of hadronic resonance production in heavy-ion collisions at the LHC has led to the observation of a prolonged hadronic phase after hadronisation. Due to their short lifetimes, resonances experience the competing effects of regeneration and rescattering of the decay products in the hadronic medium. Studying how the experimentally measured yields are affected by these processes...
A combination of projection studies of non-resonant Higgs boson pair production is performed in the $bb\gamma\gamma$ and $bb\tau\tau$ decay channels with the ATLAS detector, assuming 3000/fb of proton-proton collision data at a center-of-mass energy of $\sqrt{s} = 14~\rm TeV$ at the HL-LHC. The projected results are based on extrapolations of the Run 2 analyses conducted with 139/fb data at...
We investigate the potential reach of a search for a long-lived dark vector boson, a dark $Z$ or $Z_D$, through exotic decays of the standard model (SM) Higgs boson $h$ into either $Z_DZ_D$ or $ZZ_D$. In addition, we study a decay of $h$ into two dark Higgs bosons $h_Dh_D$. We consider the production of the SM Higgs boson at the large hadron collider (LHC) via gluon-gluon fusion and use...
LHC forward (LHCf) experiment measures forward neutral particles to improve hadronic interaction models adopted in cosmic-ray air shower simulations. This summer, we plan to have a data taking in proton-proton collisions. We expect ten times larger statistics than the previous operation in 2015 which allows us to measure pi0 and eta mesons more precisely. Moreover, we plan to have a joint...
Precise knowledge of proton parton distribution functions is a crucial element of accurate predictions of both Standard Model and Beyond Standard Model physics at hadron colliders such as the LHC. We present a PDF fit at next-to-next-to-leading order in QCD demonstrating the constraining power of a diverse range of ATLAS measurements, in combination with deep-inelastic scattering data from...
QuarkNet is a U.S. program for professional development of high school teachers. In QuarkNet, teachers deepen their understanding of physics, pedagogy, and how to engage students through the use of authentic data from a diverse set of contemporary particle physics experiments. The LHC figures prominently in these efforts. QuarkNet promotes and manages International Particle Physics...
Discriminating quark and gluon jets is a long-standing topic in collider phenomenology. In this paper, we address this question using the Lund jet plane substructure technique introduced in recent years. We present two complementary approaches: one where the quark/gluon likelihood ratio is computed analytically, to single-logarithmic accuracy, in perturbative QCD, and one where the Lund...
After the discovery of Higgs boson by the ATLAS and CMS Collaborations, a new era of the precise determination of the properties of this new particle has begun. In recent years, experimental searches for rare Higgs decays, like $h\to V\gamma$ ($V$ denotes vector mesons $\rho$, $\phi$, $J/\psi$ and $\Upsilon$ etc.) and $h\to VV (V=J/\Psi, \Upsilon$) have been performed at the LHC.
Motivated...
The Phase 2 upgrade of the CMS muon spectrometer will include the installation of three new muon stations based on Gas Electron Multiplier (GEM) technology. One of the three stations, ME0, will increase the acceptance for muon detection in the region 2.03 < |η| < 2.82 where there is a high radiation background. When triple-GEM detectors, including ME0, operate at high gain, there are...
At critical point a system undergoing phase transition is characterized by large fluctuations in the observables. Fluctuation study is thus one of the important techniques to explore phases of the QCD matter and to search for the critical end point of hadron-quark or quark-hadron phase boundary. Scaling properties of the multiplicity fluctuations of hadrons produced in the high energy heavy...
This poster presents a search for Dark Matter produced in association with a Higgs boson decaying to b-quarks using the data corresponding to an integrated luminosity of 139/fb collected with the ATLAS detector in pp collisions at $\sqrt{s}=13\rm~TeV$ at the Large Hadron Collider. The targeted Events typically contain large missing transverse momentum and either two b-tagged small-radius jets...
A new search for the electroweak production of supersymmetric particles decaying into two leptons with missing transverse momentum is presented. Assuming R-parity conservation, two simplified models are considered: direct pair production of sleptons decaying into the lightest neutralinos through leptons of the Standard Model (SM) and direct pair production of the lightest charginos decaying...
Four top-quark production, a rare process in the Standard Model (SM) with a cross-section around 12 fb, is one of the heaviest final states produced at the LHC, and it is naturally sensitive to physics beyond the Standard Model (BSM). A data excess is observed with twice of the expectation. A follow-up analysis is the search for Heavy (pseudo)Higgs boson A/H produced in association with a...
New long-lived particles are a feature of many extensions to the Standard Model, and their unique detector signatures may elude searches for promptly decaying particles. An analysis of data collected in pp collisions at √s = 13 TeV with the ATLAS detector at the Large Hadron Collider is described, focusing on identifying jets produced by neutral long-lived particles decaying to Standard Model...
A search for resonant Higgs boson pair production in the 4b final state is presented. The analysis uses up to 139/fb of pp collision data at $\sqrt(s) = 13~\rm TeV$ collected with the ATLAS detector. The analysis is divided into two categories, targeting Higgs boson decays which are reconstructed as pairs of jets or as single large-radius jets. Two benchmark signal models are considered: a...
A search is made for a vector-like $T$ quark decaying into a Higgs boson and a top quark in 13 TeV proton-proton collisions using the ATLAS detector at the Large Hadron Collider with a data sample corresponding to an integrated luminosity of $139\rm~^{-1}$. The all-hadronic decay modes $H\to b\bar{b}$ and $t\to bW\to bq\bar{q'}$ are reconstructed as large-radius jets and identified using...
The dimuon decay of the Higgs boson is the most promising process for probing the Yukawa couplings to the second generation fermions at the Large Hadron Collider (LHC). In this poster, we present a search for this important process using the data corresponding to an integrated luminosity of $139 fb^{−1}$ collected with the ATLAS detector in pp collisions at $\sqrt{s}=13\rm ~TeV$ at the LHC....
Results from the CMS experiment are presented for searches for supersymmetric particles with decays to hadronic final states. The searches use proton-proton collision data with luminosity up to 137 fb-1 recorded by the CMS detector at center of mass energy 13 TeV during the LHC Run 2.
Resistive Plate Chambers (RPCs) are gaseous detectors with parallel plate geometry and resistive electrodes, widely employed at the LHC. In ALICE (A Large Hadron Collider Experiment) 72 RPCs are installed in the forward muon spectrometer and provide muon identification.
The ALICE RPCs are operated with a mixture of 89.7% $C_{2}H_{2}F_{4}$, 10% i-$C_{4}H_{10}$ and 0.3% $SF_{6}$....
Communicating the science and achievements of the ATLAS Experiment is a core objective of the ATLAS Collaboration. This talk will explore the range of communication strategies adopted in ATLAS communications, with particular focus on how these have been impacted by the COVID-19 pandemic. In particular, an overview of ATLAS’ digital communication platforms will be given – with focus on social...
We extend the classical phase-space distribution function to include the spin and electromagnetic fields coupling and derive the modified constitutive relations for charge current, energy-momentum tensor, and spin tensor. Because of the coupling, the new tensors receive corrections to their perfect-fluid counterparts and make the background and spin fluid equations of motion communicate with...
The increased radiation environment and data rate for the High Luminosity Large Hadron Collider (HL-LHC) require upgrades to the readout electronics for the Muon Spectrometer ( MS ) electronics. In this talk, I will present the status of the irradiation studies for the chamber service module (CSM). The CSM is a custom-built front-end electronics board and is responsible for multiplexing data...
A precise measurement of the luminosity is an essential part of the ATLAS physics program and is of particular importance to cross-section measurements, where it can be one of the largest systematic uncertainties. The track-counting method is one of several approaches used within ATLAS to compute the luminosity and involves counting the number of charged-particle tracks reconstructed in the...
Hadronic resonances can act as useful probes to examine the hadronic phase in ultra-relativistic heavy-ion collisions. In addition, high $p_{T}$ resonances could probe not only the hadronic phase but also the partonic phase if they are created very early in jet fragmentation. Hadron-resonance angular correlations could help to preferentially select high transverse momentum resonances coming...
The ATLAS experiment is being upgraded to take advantage of the improved running conditions foreseen for the Run 3 and High Luminosity LHC operation phase. Part of this upgrade consists in removing the original Small Wheels located in the Muon Spectrometer, and replacing them with two New Small Wheels (NSWs). The exploited technologies for the upgrade are Small-Strips Thin Gap Chambers (sTGC)...
After successfully completing the phase-I upgrades during the long-shutdown 2 of LHC, the ATLAS detector is now ready to take Run3 collision data, with several upgrades implemented. The most important and challenging being in the Muon Spectrometer, where the two forward inner muon stations have been replaced with the New Small Wheels (NSW) equipped with two completely new detector...
The present ATLAS Small Wheel Muon detector will be replaced with a New Small Wheel(NSW) detector in order to cope up with the future LHC runs of high luminosity.One crucial part of the integration procedure concerns the validation of the electronics for a system with more than 2.1 M electronic channels.The readout chain is based on optical link technology connecting the backend to the...
The High-Luminosity LHC (HL-LHC) will usher a new era in high-energy physics. The HL-LHC experimental conditions entail an instantaneous luminosity of up to 75 Hz/nb and up to 200 simultaneous collisions per bunch crossing (pileup). To cope with those conditions, the CMS detector will undergo a series of improvements, in what is known as the Phase-2 upgrade. In particular, the upgrade of the...
Events with muons in the final state are fundamental for detecting a large variety of physics processes in the ATLAS Experiment, including both high precision Standard Model measurements and new physics searches. For this purpose, the ATLAS Muon Trigger has been designed and developed into two levels: a hardware based system (Level-1) and a software based reconstruction (High Level Trigger)....
The Large Hadron Collider (LHC) is the world’s highest energy particle accelerator, providing ultimately unique opportunities of directly searching for new physics Beyond the Standard Model (BSM). Massive long-lived particles (LLPs), which are absent in the Standard Model, can occur in many well-motivated theories of physics BSM. These new massive LLPs can decay into other particles away from...
The performance of the Inner Detector tracking trigger of the ATLAS experiment at the LHC is evaluated for the data taking period of Run-2 (2015-2018). The Inner Detector tracking was used for the muon, electron, tau and b-jet triggers, and its high performance is essential for a wide variety of ATLAS physics programs such as many precision measurements of the Standard Model and searches for...
In the Standard Model (SM), the $b \to s$ and $b \to d$ flavor-changing neutral currents (FCNC), being loop-induced, are standard experimental channels for testing the SM precisely and searching for possible physics beyond the SM. Purely annihilation decays of $B$-mesons are of significant interest as in the SM they are extremely suppressed and New Physics effects can increase substantially...
Event shape observables such as transverse spherocity($S_{0}$) have evolved as a
powerful tool to separate soft and hard contributions in an event in small collision
systems. To understand this phenomenon, we used two-particle differential-number
correlation functions, $R_{2}$, and transverse momentum correlation functions, $P_{2}$, of
charged particles produced in pp collisions at the LHC...
The event-by-event fluctuations of the average transverse momentum, $\langle p_{\rm{T} }\rangle$, are studied as a function of transverse spherocity and average multiplicity in p$-$p collisions using PYTHIA8 event generator at $\sqrt{s}= 7$ TeV and 13 TeV. We compared the results for different spherocity classes to understand the contribution from the underlying events. Also, the energy...
Transverse spherocity is a tool that separates events based on geometrical shapes, i.e., jetty and isotropic events. Transverse spherocity based studies are widely understood in small systems like proton-proton (pp) collisions in simulations and experiments, but it is yet to be explored in heavy-ion collisions. In this work, we attempt to study different global observables in heavy-ion...
The identification of jets containing b-hadrons, b-tagging, is critical for many ATLAS physics analyses. Its performance is measured in data and the simulation is corrected through simulation-to-data scale factors. However, such measurement only covers a certain jet $p_T$ range, so the b-tagging performance at higher $p_T$ must be evaluated via a simulation-based extrapolation method. This...
The Tile Calorimeter (TileCal) is a sampling hadronic calorimeter covering the central region of the ATLAS experiment, with steel as absorber and plastic scintillators as active medium. The High-Luminosity phase of LHC, delivering five times the LHC nominal instantaneous luminosity, is expected to begin in 2029. TileCal will require new electronics to meet the requirements of a 1 MHz trigger,...
The ATLAS physics program for HL-LHC assumes that luminosity will be measured with a precision of at least 1%, the proton-proton collision rate being as large as 200 interactions per bunch crossing. In order to reach this goal, ATLAS will have several luminosity monitors. Among them, LUCID-3 will be one of the few with enough acceptance to measure absolute luminosity during van der Meer scans,...
The associated production of a Higgs and a Z boson at the LHC receives an important contribution from the gluon-initiated channel $gg \rightarrow ZH$. Currently, exact analytic results for the NLO QCD corrections to this partonic process are not known, due to the presence of top-quark-mediated two-loop box diagrams in the virtual contribution. The inclusion of the gluon-initiated component at...
The spin structure of the weak gauge bosons produced at non-zero transverse momentum at proton-proton colliders leads to a parametrization of the cross section of the Drell-Yan process by a set of eight angular coefficients. These coefficients have been measured for the Z-boson by various experiments. The W-boson mass measurement at the LHC relies in part on precise knowledge of the W-boson...
