Recent measurements of charm-baryon production at midrapidity by the ALICE collaboration in pp collisions show baryon-over-meson ratios significantly higher than those in $\rm e^+e^-$ collisions for different charm-hadron species. The charmed baryon-to-meson and charmed baryon-to-baryon ratios provide unique information on hadronisation mechanisms. In this poster, the first measurement of...
The production cross sections of open heavy-flavour hadrons are typically described within the factorisation approach as the convolution of the parton distribution functions of the incoming protons, the perturbative QCD partonic cross section, and the fragmentation functions. These last are typically parametrised from measurements in ${\rm e^+e^-}$ collisions. Measurements of charm-baryon...
The increase of the particle flux (pile-up) at the HL-LHC with instantaneous luminosities up to
L ~ 7.5 × 10$^{34}$ cm$^{-2}$s$^{-1}$ will have a severe impact on the ATLAS detector reconstruction and trigger performance. The end-cap and forward region where the liquid Argon calorimeter has coarser granularity and the inner tracker has poorer momentum resolution will be particularly...
In the Standard Model (SM), lepton flavour is conserved in all interactions.
Hence, any observation of lepton flavour violation (LFV) would be an
unambiguous sign of physics beyond the SM (BSM), and LFV processes are
predicted by numerous BSM models.
One way to search for LFV is in the decay of gauge bosons.
In the search presented here, the decay of the Z boson to an electron-tau...
Since 2016 ATLAS detector is equipped with new devices - ATLAS Forward Proton (AFP) detectors. AFP aims to measure protons scattered at very small angles, which are a natural signature of so-called diffractive events. Measurement of properties of diffractive events usually require low pile-up data-taking conditions. AFP performance in such special, low pile-up runs, including evaluation of...
Production of beauty quarks takes place mostly in initial hard scattering processes and can be calculated using perturbative quantum chromodynamics (pQCD). Thanks to excellent particle tracking capabilities, the ALICE experiment at the LHC is able to reconstruct beauty-hadron decay vertices, displaced hundreds of micrometers from the primary interaction vertex. The poster will present...
Heavy quarks (charm, beauty), due to the large masses, mainly originate via hard partonic scattering processes in high-energy hadronic collisions. They evolve as parton showers and hadronize as back-to-back jet events.
Two particles azimuthal angular correlations triggered by electrons from heavy-flavour hadron decays can be used for heavy-flavor jet studies. Such correlation...
In this work we present the production of charged particles associated with high-$p_{\rm T}$ trigger particles ($8<\textit{p}_{\rm T}^{\rm trig.}<15$ GeV/$c$) at midrapidity in proton-proton collisions at $\sqrt{s}=5.02$,TeV simulated with the PYTHIA 8 Monte Carlo model [1]. The study is performed as a function of the relative transverse activity classifier, $R_{\rm T}$, which is the relative...
Liquid argon (LAr) sampling 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. In the first LHC run a total luminosity of 27 fb$^{−1}$ has been collected at center-of-mass energies of 7-8 TeV. After detector consolidation during a long shutdown, Run-2...
This poster summarises the extra dimensional models being searched for using the ATLAS detector at the Large Hadron Collider, in the full Run 2 dielectron and dimuon datasets. This data was produced in proton-proton collisions at a centre-of-mass energy of 13 TeV. In particular, the limits on the ADD model are presented, from a reinterpretation of the ATLAS Run 2 dilepton non-resonant...
Eight years ago, the discovery of a new fundamental particle, the Higgs boson (H), was announced by the ATLAS and CMS collaborations at CERN. While elementary particles acquire their mass through their interaction with the Higgs field, the large differences in their masses as well as the origin of the three generations of fermions remain unexplained to this day and constitute the Standard...
The second LHC long shutdown period (LS2) was a crucial opportunity for the CMS Resistive Plate Chambers (RPC) to complete their consolidation and upgrade projects. The consolidation includes detector maintenance for gas tightness, HV (high voltage), LV (low voltage) and slow control operation. Dedicated studies were performed to understand the behaviour of RPC currents with comparison to...
Standard dipole parton showers are known to yield incorrect subleading-colour contributions to the leading (double) logarithmic terms for a variety of observables. In this work, concentrating on final-state showers, we present two simple, computationally efficient prescriptions to correct this problem, exploiting a Lund-diagram type classification of emission regions. We study the resulting...
Several Dark Sector models predict the existence of particles with macroscopic life-times and semi-visible jets (QCD-like jets which include stable Dark Sector particles). These can lead to final states with large missing transverse momentum recoiling against at least one highly energetic jet, a signature that is often referred to as a mono-jet.
The RECAST framework is used to re-interpret...
In this study, a new technique for event classification using Convolutional Neural Networks (CNN) is presented. Results obtained using this technique are shown and compared to more traditional Machine Learning approaches for two different physics cases.
The new technique explores the power of visual recognition, which is one of the fastest-growing areas in Artificial Intelligence, as a...
The momentum anisotropy ($v_{n}$) of the produced particles in relativistic nuclear collisions is considered to be a response of the initial geometry or the spatial anisotropy ($\varepsilon_{n}$) of the system formed in these collisions. The linear correlation between $\varepsilon_{n}$ and $v_{n}$ measures the efficiency at which the initial spatial eccentricity is converted to final momentum...
The ATLAS Muon Upgrade project is a part of the Large Hadron Collider (LHC) - High Luminosity (HL) upgrade project which aims to increase its instantaneous luminosity up to 7.5X10$^{34}$ cm$^{−2}$s$^{−1}$. The present first muon station in the forward regions of ATLAS is being replace by the so-called New Small Wheels (NSWs). The NSWs consist of resistive-strip MicroMegas (MM) detectors and...
We study new physics contributions to CP-violating anomalous couplings of top-quark in the context of top-pair production and their consequent decays into a pair of dilepton and b-jets at the Large Hadron Collider. An estimate of sensitivities to such CP-violating interactions would also be discussed for the pre-existing 13 TeV LHC data and its projections for the proposed LHC run at 14 TeV.
Next-generation collider experiments will have to cope with extremely high collision rates, making it necessary to implement real-time event processing capabilities. Among the standard pattern recognition algorithms thought to be run on Look-Up Tables, Machine Learning methods, and in particular Deep Neural Networks, are spreading very fast and there is growing interest in executing such...
The High-Luminosity LHC will open an unprecedented window on the weak-scale nature of the universe, providing high-precision measurements of the Standard Model (SM) as well as searches for new physics beyond the SM. The CMS Collaboration is planning to replace entirely its trigger and data acquisition systems to match this ambitious physics program. Efficiently collecting datasets in Phase 2...
The increase of luminosity foreseen for the High-Luminosity LHC phase requires the substitution of the ATLAS Inner Detector with a new tracking detector, called Inner Tracker. It will be an all-silicon system consisting of a pixel and a strip subdetector. The ATLAS wide FELIX system will be the off-detector interface to the Inner Tracker.
In order to efficiently bring the Inner Tracker into...
To meet new TDAQ buffering requirements and withstand the high expected radiation doses at the high-luminosity LHC, the ATLAS Liquid Argon Calorimeter readout electronics will be upgraded. The triangular calorimeter signals are amplified and shaped by analogue electronics over a dynamic range of 16 bits, with low noise and excellent linearity. Developments of low-power preamplifiers and...
A series of upgrades are planned for the LHC accelerator to increase it's instantaneous luminosity to 7.5×10$^{34}$ cm$^{-2}$s$^{-1}$. The luminosity increase drastically impacts the ATLAS trigger and readout data rates. The present ATLAS Small Wheel Muon detector will be replaced with a New Small Wheel (NSW) detector which is expected to be installed in the ATLAS underground cavern by the end...
Single top quark production is the subleading production process of top quarks at the LHC after the top quark pair production. The latest differential measurements of single top quark production (tW) cross sections are presented using data collected by the CMS detector at a center-of-mass energy of 13 TeV. The cross sections are measured as a function of various kinematic observables of the...
Although most of Beyond Standard Model (BSM) searches are targeting specific theory models, there has always been a keen interest in the development of model-independent methods amongst the High Energy Physics(HEP) community. Machine Learning (ML) based anomaly detection stands among the latest up-and-coming avenues for creating model-agnostic BSM searches. The focus of this research is the...
A search is presented for four-top-quark production using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the Large Hadron Collider with an integrated luminosity of 139/fb. Events are selected if they contain a same-sign lepton pair or at least three leptons (electrons or muons). Jet multiplicity, jet flavour and event kinematics are used to...
The formation of partonic medium in the relativistics heavy-ion collisions is always marked by the values of the ratio of certain observables assuming $p+p$ collisions as a reference. But recent studies of small systems formed in $p+p$ collisions at the LHC energies hint towards the possibility of production of medium with collective behaviour. Results from $p+p$ collisions have routinely been...
Over the last years, Machine Learning (ML) tools have been successfully applied to a wealth of problems in high-energy physics. In this talk, we will discuss the extraction of the average number of Multiparton Interactions ($〈N_{mpi}〉$) from minimum-bias pp data at LHC energies using ML methods. Using the available ALICE data on transverse momentum spectra as a function of multiplicity we...
To achieve the challenging target of 1% precision on luminosity determination at the high-luminosity LHC (HL-LHC) with instantaneous luminosity up to $7.5 × 10^{34} cm^{−2} s^{−1}$, the CMS experiment will employ multiple luminometers with orthogonal systematics. A key component of the proposed system is a stand-alone luminometer, the Fast Beam Condition Monitor (FBCM), which is fully...
The ATLAS Forward Proton physics program at CERN aims at studying soft and hard diffractive events from ATLAS proton collisions. Time-of-Flight (ToF) system is used to reduce the background from multiple proton-proton collisions. In this presentation, we describe technical details of the Fast Cherenkov model of photons generation and transportation through the optical part of the ToF detector....
The New Small Wheel (NSW) upgrade is now in its commissioning phase. The future ATLAS detector sub-system will be one of the first to employ the Front-End Link eXchange (FELIX) as its Data Acquisition (DAQ) scheme. Currently, one of the main focus points of the community is to ensure proper acquiring of data from the detector media, besides validating the performance of the detectors...
The precise knowledge of the strong interaction between kaons and nucleons
is a key element to describe the interaction between hadrons in the non-perturbative regime of QCD.
Moreover, the knowledge of this interaction plays an important role in the study of the equation
of state of dense baryonic matter, and hence has important implications for the
modeling of neutron stars.
We...
The design and the status of the development of the Level-0 endcap muon trigger firmware for the ATLAS experiment at the HL-LHC are presented. The firmware reconstructs muon candidates with an improved momentum resolution by exploiting all hit data from Thin Gap Chambers (TGCs) to be available at XCVU13P FPGA mounted on the trigger and readout boards. The track segment is reconstructed by a...
FASER (ForwArd Search ExpeRiment) fills the axial blindspot of other, radially arranged LHC experiments. It is installed 480 meters from the ATLAS interaction point, along the collision axis. FASER will search for dark matter and other new, long-lived particles that may be hidden in the collimated reaction products exiting ATLAS. FASER comprises: a magnetic spectrometer built with ATLAS...
ALICE analysis mostly deals with large datasets using the distributed Grid infrastructure. In Run 1 and 2, ALICE developed a system of analysis trains (so-called “LEGO trains”) that allowed the user to configure analysis tasks (or wagons) that are expected to be run on the same data. The LEGO train system builds upon existing tools: the ALICE analysis framework as well as the Grid submission...
Machine learning techniques have been quite popular recently in the high-energy physics community and have led to numerous developments in this field. In heavy-ion collisions, one of the crucial observables, the impact parameter, plays an important role in the final-state particle production. This being extremely small (i.e. of the order of a few fermi), it is almost impossible to measure...
The top quark pair production cross section is measured in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data collected in 2017 by the CMS experiment at the LHC corresponding to an integrated luminosity of 304 1/pb are analyzed. The measurement is performed using events with one electron and one muon of opposite sign, and at least two jets. The measured cross section is...
Hadronic resonances are short-lived particles whose lifetimes are comparable to the hadronic phase lifetime of the system produced in ultrarelativistic nucleon-nucleon or nuclear collisions. These 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. In...
The non-perturbative QCD effects involved in radiative tau decay $(\tau^- \rightarrow \pi^- \nu_\tau \gamma)$ are encoded in two form factors; the vector ($F_V$) and the axial vector ($F_A$) form factors. We present the computation of these form factors using light cone sum rules. The form factors involved in this decay are same as involved in radiative pion decay with the crucial difference...
The High Luminosity upgrade of the LHC (HL-LHC) places unprecedented requirements for background monitoring and luminosity measurements. The CMS Tracker Endcap Pixel Detector (TEPX) will be adapted to provide high-precision online measurements of bunch-by-bunch luminosity and beam-induced background. The implementation of dedicated triggering and readout systems, the real-time clustering...
The precise determination of the luminosity in a collider is of crucial importance for any physics cross sections measurement since it directly translates to the precision of the cross section determination.
In a muon collider dense muon beams are necessary to achieve the target luminosity, these beams generate very high fluxes of particles coming from the muons decay along the beam...
The LUXE experiment (LASER Und XFEL Experiment) is a new experiment in planning at DESY Hamburg using the electron beam of the European XFEL. LUXE is intended to study collisions between a high-intensity optical LASER and 16.5 GeV electrons from the XFEL electron beam, as well as collisions between the optical LASER and high-energy secondary photons. The physics objective of LUXE are processes...
Jet identification tools are crucial for new physics searches at the LHC and at future colliders. We introduce the concept of Mass Unspecific Supervised Tagging (MUST) which relies on considering both jet mass and transverse momentum varying over wide ranges as input variables - together with jet substructure observables - of a multivariate tool. This approach not only provides a single...
Heavy quarks (charm and beauty) are produced at the initial stages of the relativistic hadronic collisions in hard scattering processes, and the study of their production in proton-proton (pp) collisions is an important test for calculations based on perturbative Quantum Chromodynamics (pQCD). Analysis of heavy flavor production as a function of charged-particle multiplicity provides insight...
The ratios of the Bc(2S) to Bc, Bc(2S) to Bc, and Bc(2S) to Bc(2S) production cross sections are measured in proton-proton collisions at 13 TeV, using a data sample collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 143 fb−1. The three measurements are made in the Bc meson phase space region defined by the transverse momentum pT > 15 GeV and absolute...
Recent measurements of the Higgs boson production cross section in the H->WW decay channel using proton-proton collision data with CMS experiment at 13 TeV will be presented. In particular the Higgs boson production in association with leptonically decaying vector bosons is targeted, and the H->WW decays in which at least one W boson decays to leptons are considered. Results for both the...
The discovery of the Higgs boson in 2012 by the CMS and ATLAS collaborations marked the start of the exploration of the Higgs sector of particle physics. The properties of the Higgs sector under CP symmetry have been investigated mostly in its couplings to gauge bosons. With the full Run 2 data-taking period it became possible to study the CP properties of the Yukawa coupling of the Higgs to...
A measurement of four-top-quark production using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the Large Hadron Collider with an integrated luminosity of 139/fb is presented. A new result uses events with a single lepton (electron or muon) or an opposite-sign lepton pair, in association with multiple jets. The measured four-top-quark...
A measurement of the associated production of a single top quark and a W boson in the final states with an electron or muon and jets using pp collisions with $\sqrt{s} = 13$ TeV collected by the CMS detector at the CERN LHC is presented. The data used correspond to an integrated luminosity of 36 fb$^{-1}$ . This result is the first observation of the tW process in the final states containing a...
After the discovery of the Higgs boson and its characterisation, we are entering in the precision era of the Higgs physics where we need robust measurements to spot any sign of BSM physics. Among the many available tools, fiducial measurements are one of the most used in HEP due to their model independence, longevity, and easy comparison with theoretical predictions. The production cross...
At high energy collisions, such as those achieved at the LHC, particle production is dominated by soft-QCD processes. The soft production is described by non-perturbative QCD and challenges existing phenomenological models. Global observables such as multiplicity and rapidity dependence of particle production are some of the most fundamental measurements for improving and constraining these...
An increasing center-of-mass energy of proton-proton collisions and higher luminosities at the CERN Large Hadron Collider make it possible to study rare processes of the Standard Model (SM). In this poster, the measurements of both the inclusive and differential cross sections of top-quark–antiquark production in association with a Z boson (ttZ) are presented. Collision data corresponding to a...
We explore a new center-of-mass energy at 5 TeV, to study diboson production in proton-proton collisions using data collected with the CMS detector. The WW, WZ, and ZZ cross sections are measured analyzing events with two, three, or four charged leptons in the final state. These measurements are compared with the best available theoretical predictions and across other experiments.
Explaining the tiny neutrino masses and non-zero mixings have been one of the key motivations for going beyond the framework of the Standard Model (SM). We discuss a collider testable model for generating neutrino masses and mixings via radiative seesaw mechanism. That the model does not require any additional symmetry to forbid tree-level seesaws makes its collider ...
The ATLAS Muon Spectrometer is going through an extensive Phase I upgrade to cope up with the future LHC runs of high luminosity of up to 7.5×10$^{34}$ cm$^{-2}$s$^{-1}$. The innermost and first station of the Muon end cap system, the Small Wheel, will be replaced by the New Small Wheel, which has high trigger and precision tracking capabilities. This is achieved by a combination of two...
Longitudinal polarisation of the weak bosons is a direct consequence of Electroweak symmetry breaking mechanism providing an insight into its nature, and is instrumental in searches for physics beyond the Standard Model. We perform a polarisation study of the diboson production in the $pp \to e^+ \nu_e \mu^- \bar\nu_\mu$ process at NNLO QCD in the fiducial setup inspired by experimental...
The measurement of azimuthal correlations between two particles is a powerful tool to investigate the properties of strongly-interacting nuclear matter created in ultra-relativistic heavy-ion collisions. In particular, studying the near-side and away-side hadron yields associated with trigger particles can provide important information to understand both the jet -medium interaction and hadron...
The muon system of the CMS experiment has been instrumented with two wheels of triple-GEM detectors in order to ensure redundancy in the pseudo-rapidity region 1.55-2.2 so keeping the trigger rate at an acceptable level while not compromising the CMS physics potential in Run 3 of the LHC. The station, named GE1/1, provides two additional muon hit measurements which will improve the muon...
The High Luminosity Large Hadron Collider (HL-LHC) will deliver five times the LHC nominal instantaneous luminosity, after a series of upgrades that will take place during the shutdown of 2024 –2026. The ATLAS Hadronic Calorimeter (TileCal) will require the complete replacement of the readout electronics in order to accommodate its acquisition system to the increased radiation levels, trigger...
With the end of RUN-II, the LHC has delivered only 4% of the collision data expected to be available during its lifetime. The next data-taking campaign - RUN-III - will double the integrated luminosity the LHC accumulated in 10 years of operation. The Run-III will be the herald of the HL-LHC era, an era when 90% of total LHC integrated luminosity (4 ab$^{-1}$) will be accumulated allowing...
FASER (ForwArd Search ExpeRiment) is a new, small and inexpensive experiment designed to search for light, weakly interacting particles during Run 3 of the LHC. Such particles may be produced in large quantities in proton-proton collisions, travel for hundreds of meters along the beam axis, and can decay in two charged Standard Model particles. To reach its physics goals, a good hit...
A novel outreach project is presented that makes use of playing cards – one of the most ubiquitous toys around the world – to communicate physics in a fun, engaging manner. A custom deck of cards has been designed to inspire an interest in physics while being widely appealing to the general public and useful for gameplay, magic and cardistry. In the course of bringing this project to...
Total Ionizing Dose Effects tests and measurements are crucial requirements for solid state particle sensors and electronic control systems qualification in all the LHC present experiments and future upgrades.
These measurements can be performed not only in facilities explicitly built for this mission, but with some wisdom, also in medical or biological research facilities when some minimum...
Thanks to its high luminosity and center of mass energy, the future FCC-hh collider will allow us to probe processes with clean but rare final states that are unaccessible at the LHC. The study of diboson production processes poses a promising way of indirectly constraining New Physics in the context of the Higgs Boson. Specifically, the diphoton leptonic decay channels of the Wh and Zh...
The high-luminosity upgrade of the LHC (HL-LHC) is foreseen to reach an instantaneous luminosity a factor of five to seven times the nominal LHC design value. The resulting, unprecedented requirements for background monitoring and luminosity measurement create the need for new high-precision instrumentation at CMS, using radiation-hard detector technologies. This contribution presents the...
The Compact Muon Solenoid (CMS) detector at the CERN Large Hadron Collider (LHC) is undergoing an extensive Phase II upgrade program to prepare for the challenging conditions of the High-Luminosity LHC (HL-LHC). A new timing detector in CMS will measure minimum ionizing particles (MIPs) with a time resolution of 30-40 ps for MIP signals at a rate of 2.5 Mhit/s per channel at the beginning of...
High-multiplicity events in small collision systems (pp, p-Pb) at LHC energies exhibit soft-physics phenomena that are associated with collective dynamics of the quark-gluon plasma (QGP) in large collision systems, e.g. azimuthal correlation between soft particles having large pseudo-rapidity separation. Jet quenching is likewise a necessary consequence of the formation of a QGP. However,...
This talk discusses the prospects under various scenarios of the amount of data collected and assumptions on systematic uncertainties to explore the top squark and neutralino mass degenerate corridor. The analysis technique employs a deep neural network fed with variables sensitive to top quark spin correlation and polarization in top quark pair production. In particular, different...
Explicit expressions for quantum fluctuations of energy in subsystems of a hot relativistic gas of spin-1/21/2 particles are derived. The results depend on the form of the energy-momentum tensor used in the calculations, which is a feature described as pseudo-gauge dependence. However, for sufficiently large subsystems the results obtained in different pseudo-gauges converge and agree with the...
In high-energy physics experiments, online selection is crucial to select interesting collisions from the large data volume. ATLAS b-jet triggers are designed to identify heavy-flavour content in real-time and provide the only option to efficiently record events with fully hadronic final states containing b-jets. In doing so, two different, but related, challenges are faced. The physics goal...
This poster presents a search for charged Higgs bosons decaying into 𝑊𝑊 or 𝑊𝑍 bosons, involving experimental signatures with two leptons of the same charge, or three or four leptons with a variety of charge combinations, missing transverse momentum and jets. Some focus will be given on the four leptons channel signature. A data sample of proton–proton collisions at a centre-of-mass energy of...
Many extensions of the Standard Model predict the production of Dark Matter in association with Higgs bosons.
This search examines the final state of missing transverse momentum
accompanied by a bb pair coming from a Higgs boson decay. For this purpose proton-proton
collision data is used which is produced at 13 TeV centre-of-mass energy and recorded by the
ATLAS experiment at the LHC,...
This poster presents a search for electroweak production of mass degenerate chargino-neutralino pairs in the context of R-parity conserving supersymmetric simplified models in which the chargino decays into W boson and the lightest neutralino, while the next-to-lightest neutralino decays into either Higgs or Z boson, in addition to the lightest neutralino. This search concentrates on final...
A novel search for exotic decays of the Higgs boson to pairs of long-lived
neutral particles, each decaying to a bottom quark pair, is performed
using 139 fb$^{-1}$ of $\sqrt{s} = 13$ TeV proton-proton collision data
collected with the ATLAS detector at the LHC. Events consistent with the
production of a Higgs boson in association with a $Z$ boson are analyzed,
with the leptonic decay of...
This poster presents the search for new resonances decaying into a W boson and a 125GeV Higgs boson in the lvbb final state, where l=e+- or mu+-, in pp collisions at root(s)=13TeV. The search includes a channel requiring one lepton and missing transverse energy, as well as a channel with only missing transverse energy for the case where the lepton is not reconstructed. The data used correspond...
A Multi-TeV (√s=1.5-10TeV) muon collider providing O(1/ab)integrated luminosity will be a great opportunity to probe the most intimate nature of the Standard Model (SM) and the Electroweak Symmetry Breaking mechanism, allowing the precise measurement of the Higgs couplings to several SM particles. The study of the Higgs boson couplings to the second generations of fermions is of particular...
A muon collider represents the ideal machine to reach very high center-of-mass energies (√s=1.5-10TeV) and luminosities O(0.5-10/ab). A large number of Higgs bosons will be produced mainly through the Vector Boson Fusion (VBF) processes. The VBF through Z bosons (ZZH) production process could be difficult to disentangle to the dominant WWZ, since the final state VBF muons, produced in the very...
Small collision systems, such as pp or p-Pb, exhibit signatures of collective effects that are thought to be associated with quark-gluon plasma formation. The absence to date of jet quenching signals raises a question about the origin of the observed collectivity and calls for more accurate jet quenching measurements in small collision systems. In this poster, the ALICE Collaboration reports...
To address the incompleteness of the Standard Model (SM), many models introduce new gauge fields and interactions, which manifest as new particles with TeV scale masses. Thus, it is imperative to understand particles and interactions at the TeV scale. An example of one such particle is the $Z^\prime$ boson, a heavy, neutral spin-1 gauge boson. Numerous ideas exist to probe the TeV scale,...
Several theoretical models of Beyond the Standard Model (BSM) physics predicts the production of new resonances at hadron collider experiments. This study, in particular, is focused on the search for Quantum Black hole (QBH) and existence of substructure of light and heavy flavor quarks in the photon + jet final state in the proton-proton collisions at a centre of mass energy of 13 TeV using...
We present a search for non-resonant di-Higgs production in the HH->bbyy decay channel. The measurement uses 139ifb of pp collisions recorded by the ATLAS experiment at a center-of-mass energy of 13 TeV. Selected events are separated into multiple regions, targeting both the SM signal and BSM signals with modified Higgs self-couplings. No excess with respect to background expectations are...
The trilninear self-coupling of Higgs can directly be accessed at the LHC by inclusive production of Higgs pair. A search for the non-resonant Higgs pair production via gluon-gluon fusion (ggF) and as well as Vector Boson Fusion (VBF) processes has been performed recently by CMS collaboration with the complete LHC Run-2 proton-proton collision data at center of mass energy of $\sqrt{s}$=13...
A search for scalar top quark pair production at the LHC with the CMS experiment is presented. This search targets a region of parameter space where the kinematics of top squark pair production and top quark pair production are very similar because of the mass difference between the top squark and the neutralino being close to the top quark mass. The search is performed with the full run 2...
A study of long-lived dark Z boson that either couples directly to quarks or mixes kinetically with the standard model Z boson is performed. Production via a vector portal and the Higgs portal are considered. The impact of additionally mixing the standard model Higgs boson with a dark Higgs boson on the production and decays of the dark Z is evaluated. Specifically, decays with a final state...
A search is performed for W' bosons decaying to a top and a bottom quark in the all-hadronic final state, in proton-proton collisions at a center-of-mass energy of 13 TeV using the data collected by the CMS experiment between 2016 and 2018, corresponding to an integrated luminosity of 137 fb$^{-1}$. Deep neural network algorithms are used to identify the jet initiated by the bottom quark and...
The Strongly Interacting Massive Particle (SIMP) paradigm has recently been increasingly studied. It provides dark matter candidates as pseudo-Goldstone bound states of dark fermions under a new gauge group. In this scenario freezeout occurs through $3\to 2$ dark matter self-annihilation and points to DM particles with masses of $\mathcal O(100 ~\text{MeV})$. We study the spectrum of the...
As known, nuclear periphery in heavy nuclei is enriched by neutrons. Neutron-to-proton ratio is especially high in a very thin (<0.5 fm) surface layer of such nuclei termed neutron skin (NS). The difference between RMS radii of neutron and proton density distributions is also subtle and difficult to measure. The results obtained with different theoretical and experimental methods are...
Machine learning (ML) is pushing through boundaries in computational physics.
Jet physics, with it's large and detailed dataset, is particularly well suited.
In this poster I will present work done in https://arxiv.org/abs/2104.01972 on
the application of an unusual ML technique, Spectral Clustering, to jet formation.
Spectral clustering differs from much of ML as it has no "black-box"...
The production of strange and multi-strange hadrons in heavy-ion collisions is enhanced with respect to minimum bias pp collisions. This feature has been further investigated by studying pp collisions as a function of the produced charged particle multiplicity. In pp collisions, the strange hadron yields normalised to the pion yield show an increase with the multiplicity of produced particles....
ATLAS New Small Wheels upgrade project plans to replace the inner parts of the end-caps of ATLAS Muon Spectrometer with new mechanical structures equipped by a combination of small Thin Gap Chambers (sTGC) and resistive MicroMegas (MM) detectors. During the integration of detectors, the sTGC and MM are separately tested before to be assembled. On MM detectors, tests on the noise are performed...
Sophisticated machine learning techniques have promising potential in search for physics beyond Standard Model (BSM) in Large Hadron Collider (LHC). Convolutional neural networks (CNN) can provide powerful tools for differentiating between patterns of calorimeter energy deposits by prompt particles of Standard Model and long-lived particles predicted in various models beyond the Standard...
Jets are collimated emission of multitude of hadrons which originate from the hard partonic scatterings. They play an important role as hard probes of Quark-gluon plasma (QGP). These hard jets lose their energy through medium-induced gluon radiation and collisonal energy loss. This suppression of final state hadrons at high $p_{\rm T}$ is referred to as jet quenching. Jet quenching is an...
Angularity definition
Angularities are a class of observables of interest for jet phenomenology at the LHC. They are defined by
\begin{equation}
\lambda_\alpha^\kappa=\sum_{i\in\text{jet}}\left(\frac{p_{T, i}}{\sum_{j\in\text{jet}}p_{T, j}}\right)^\kappa \left(\frac{\Delta_i}{R_0}\right)^\alpha
\end{equation}
where $R_0$ is the jet radius...
In conjunction with the High Luminosity upgrade of the LHC, the ATLAS detector is also undergoing an upgrade to handle the significantly higher data rates. The muon end-cap system upgrade in ATLAS, lies with the replacement of Small Wheel. The New Small Wheel is expected to combine high tracking precision with upgraded information for the Level-1 trigger. To accomplish this, sTGC (small Thin...
We describe the performance of the ATLAS Forward Proton Time-of-Flight detector (ToF) in Run2 and the upgrades made to the ToF for operation in Run3. We describe picosecond laser laboratory test results, previous test beam results, and the expected operational parameters and performance of the new ToF in Run3.
During Run-2 the Large Hadron Collider (LHC) has provided, at the World's energy frontier, proton-proton collisions to the ATLAS experiment with high instantaneous luminosity of up to 2.1x10$^{34}$ cm$^{-2}$s$^{-1}$, placing stringent operational and physical requirements on the ATLAS trigger system in order to reduce the 40 MHz collision rate to a manageable event storage rate of 1 kHz, while...
Muon triggers are essential for studying a variety of physics processes in the ATLAS experiment, including both standard model measurements and searches for new physics. The ATLAS muon trigger consists of a hardware based system (Level 1), as well as a software based reconstruction (High Level Trigger). The muon triggers have been optimised during Run 2 to provide a high efficiency while...
Four years after the deployment of the ATLAS public website using the Drupal 7 content management system, the ATLAS Education & Outreach group has completed its migration to the new CERN Drupal 8 infrastructure. We present lessons learned from the development, usage and evolution of the original web site, and how the choice of technology helped to shape and reinforce our communication...
Understanding events from proton interactions with residual gas in the beam pipe, with collimators or from cosmic rays, is of primary importance to identify potential risk of damage to the accelerator and experiments.
In addition, these events represent one of the main background of non-conventional physics signatures based on tracks not pointing to the interaction point, out-of-time energy...
Scattering amplitudes are often split up into their gauge (su(N)) and kinematic (two copies of complexified su(2)) components. Since the su(N) gauge part is often calculated using flows of colour, it should similarly be possible to describe the su(2) $\oplus$ su(2) kinematics of an amplitude in terms of flows of chirality. In two recent papers (hep-ph:2003.05877 & hep-ph:2011.10075) we showed...
The MIP Timing Detector (MTD) of the Compact Muon Solenoid (CMS) will provide precision timestamps with 40 ps resolution for all charged particles up to a pseudo-rapidity of |η|=3. This upgrade will mitigate the effects of pile-up expected under the High-Luminosity LHC running conditions and bring new and unique capabilities to the CMS detector. The endcap region of the MTD, called the Endcap...
Ever since the start of the LHC operations in 2009, the mission of processing, management and storage of data collected by the LHC experiments has been executed by the Worldwide LHC Computing Grid (WLCG). When the building of the infrastructure for LHC computing started (~2001) the distributed or cloud computing was non-existent and the WLCG team had to invent all of the tools from scratch....
A series of upgrades are planned for the LHC accelerator to increase it's instantaneous luminosity to 7.5×10$^{34}$ cm$^{-2}$s$^{-1}$. The luminosity increase drastically impacts the ATLAS trigger and readout data rates. The present ATLAS Small Wheel Muon detector will be replaced with a New Small Wheel (NSW) detector which is expected to be installed in the ATLAS underground cavern by the end...
The International Particle Physics Outreach Group (IPPOG) is a network of scientists, science educators and communication specialists working across the globe in informal science education and outreach for particle physics. The primary methodology adopted by IPPOG requires the direct involvement of scientists active in current research with education and communication specialists, in order to...
The LHCb experiment is a b-physics dedicated experiment at the LHC collider. It has a wide physics program, covering different fields of interest: among others, precise measurements of the CKM matrix elements and the search for lepton flavour violation and beyond Standard Model physics.
The LHCb detector has successfully performed during the Run 1 and Run 2 of the LHC, leading to important...
A direct measurement of the Higgs self coupling is very crucial to understand the nature of electroweak symmetry breaking. This requires an observation of production of Higgs boson pair, which suffers from very low event rate even at the current LHC run. In our work, we study the prospects of observing the non-resonant Higgs pair production at the high luminosity run of the 14 TeV LHC...
The ATLAS level-1 calorimeter trigger (L1Calo) is a hardware-based system that identifies events containing calorimeter-based physics objects, including electrons, photons, taus, jets, and missing transverse energy. In preparation for Run 3, when the LHC will run at higher energy and instantaneous luminosity, L1Calo is currently implementing a significant programme of planned upgrades. The...
The ridge-like structure found in two-particle correlation from the proton-proton collision is one of the hot topics in high-energy heavy-ion physics. Since the medium produced from pp collision is not large enough to generate a high-temperature and high-density medium, called QGP, and therefore this phenomenon can not be suitablely understood through hydrodynamics, unlike in nucleus-nucleus...
Being the heaviest particle of the model, with a mass close to the electroweak scale, the top quark is an interesting candidate for searching for new physics. The electroweak couplings of the top quarks are specially relevant in many extension of the Standard Model. Indeed, as the top-quark was not produced in the previous generation of electron-positron colliders most of its electro-weak...
Since 2013, the University of Michigan has hosted a semester-long research program for undergraduate students at CERN. The students are selected from a diverse mix of small and large universities across the USA and are embedded as CERN Users in active research programs on experiments at the laboratory. The program is modelled on the highly successful NSF-funded Research Experience for...
One of the event shape observables, the transverse spherocity ($S_{0}$), has been studied successfully in small collision systems such as proton-proton collisions at the LHC as a tool to separate jetty and isotropic events. It has unique capability to distinguish events based on their geometrical shapes. In our work, we report the first implementation of transverse spherocity in heavy-ion...
The ATLAS experiment at the LHC can record about 1 kHz of physics collisions, out of an LHC design bunch crossing rate of 40 MHz. To achieve a high selection efficiency for rare physics events while reducing the significant background rate, a two-level trigger system is used.
The event selection is based on physics signatures, such as the presence of energetic leptons, photons, jets or...
Triggering long-lived particles (LLPs) at the first stage of the trigger system is very crucial in LLP searches to ensure that we do not miss them at the very beginning. The future High Luminosity runs of the Large Hadron Collider will have an increased number of pile-up events per bunch crossing. There will be major upgrades in hardware, firmware and software sides, like tracking at level-1...
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 2028. TileCal will require new electronics to meet the requirements of a 1 MHz trigger,...
After the luminosity upgrade of the Large Hadron Collider (HL-LHC), the rate capability of the muon drift tube detectors of the ATLAS experiment will be exceeded due to the higher particle background rates. In the regions between the inner barrel and endcap of the muon spectrometer the trigger selectivity is limited. Therefore 8 new small diameter (15 mm) Muon Drift Tube chambers (so-called...
The use of Effective Field Theories (EFTs) in the search of NP is becoming more and more important given the lack of clear experimental signs of BSM physics. In particular, the Standard Model EFT (SMEFT) has become one of the most popular choices. Hence, the interest in revisiting EFTs is widespread in the community. The importance of chiral anomalies, either in gauge or global symmetries, can...
Committee: Johannes Albrecht, Maria Cepeda Hermida, Tristan du Pree, Elisabetta Gallo (chair), Stefania Gori, Heather Gray, Yvonne Pachmeyer, Marek Schoenherr, José Francisco Zurita
In 2018, Dubna team assembled the first LM2 module for ATLAS New Small Wheel upgrade, replacing the innermost and first station of the Muon end cap system.
Assembled modules have to pass quality and performance tests on-site including gas leaking, high voltage and MIP efficiency measurement on cosmic stand. The latter is important also as an extention of the HV test and a check of mere...
