Jets and Heavy Flavour as QGP Probes: Experimental overview
Jets and heavy-flavour particles are powerful probes of the quark-gluon plasma (QGP) created in heavy-ion collisions at the LHC.Their production rates, angular anisotropies, and internal structure provide insights into parton energy loss, medium-induced modifications of parton showers, heavy-quark transport, and hadronization in...
The next decade of heavy-ion phenomenology will be significantly shaped by the expansion of experimental reach into far forward kinematics. Upcoming detector upgrades, such as the ALICE FoCal programme and STAR forward calorimetry, require robust theoretical baselines to interpret baryon stopping in regions where standard boost-invariant models fail. We present a fully 3+1D classical transport...
The Inner Detector of the ATLAS experiment will be completely replaced by the Inner Tracker (ITk) in preparation for the High-Luminosity upgrade of the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland. The ITk will target an operational dew point of −60 °C, requiring precise environmental monitoring to ensure reliable detector performance. With normal operation at −20 °C, and fault...
Radiation monitoring is critical for evaluating the performance and lifetime of detector components in high-energy physics (HEP) experiments. Fibre Bragg grating (FBG) sensors are particularly attractive for such environments due to their small size, electromagnetic immunity, multiplexing capability, and potential radiation tolerance. Beyond conventional temperature and strain monitoring,...
ATLAS, together with the Physics Without Frontier Program, would like to organize a full afternoon program of an open-data session to train students or delegates on accessing ATLAS open data and how to use it. This is an Outreach activity of the conference besides the Outreach that will be done at different historically disadvantaged universities before the conference. The trainees once...
Rare flavor-changing processes such as B→Ka decay offer sensitive probes of axion-like particles (ALPs) for masses below a few GeV. We study this process in the framework of QCD factorization and ALP effective theory, in which the ALP couples to the Standard Model fermions through shift-invariant derivative interactions. In contrast to previous studies, where flavor violation arises solely...
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pdftitle={Beyond the Standard Model Searches for Dark Vector Bosons: A Comparison of BDT and Parametric Neural Networks},
...
In recent years, it has been understood that collinear factorization and QCD color coherence are violated at hadron colliders in higher orders of perturbation theory. In this talk, I will review the physical origin of these phenomena, their implications (such as super-leading logarithms and coherence-violating logarithms), and the role they play with regards to PDF factorization, which is the...
The gap and crack scintillator cells (E1–E4) of the ATLAS Tile Calorimeter provide essential energy measurements in the transition region between the barrel and extended barrels, where accurate calibration is important for maintaining the calorimeter energy scale and overall detector performance. This contribution presents a measurement of the energy response of these cells using isolated...
The CMS Muon system is undergoing a comprehensive upgrade to prepare for the High Luminosity LHC (HL-LHC), ensuring optimal performance under increased particle rates and luminosity. Key upgrades include enhancements to existing detectors and electronics, as well as the addition of new muon stations to expand coverage and improve resolution. The upgrades include enhancements to both the...
Oxygen–-Oxygen (OO) collisions provide an important intermediate system between proton–proton and light-ion collisions, offering a unique opportunity to investigate particle production and collective effects in a relatively light-ion collision system.
In this contribution, OO collisions at $\sqrt{s_{\mathrm{NN}}}=5.36$ TeV were simulated using the EPOS4[1] event generator. The nuclear...
Dark matter is one of the greatest mysteries that cannot be explained by the Standard Model. Many new physics models beyond the Standard Model have been proposed to explain dark matter, and various experimental approaches, including direct, indirect, and collider searches, are being pursued. This talk provides an overview of recent dark matter searches, focusing in particular on the...
Fibre-optic sensors (FOS) are attractive for environmental monitoring in high-energy physics (HEP) experiments due to their small size, multiplexing capability, immunity to electromagnetic interference, and potential radiation tolerance. However, the development of radiation-hard fibre sensors capable of monitoring parameters such as humidity remains challenging for future detector...
Authors: Adrian William Romero Jorge, Taesoo Song, Gaia Ingrosso, Jiaxing Zhao, Elena Bratkovskaya
Dileptons are penetrating electromagnetic probes of strongly interacting matter and provide direct access to thermal radiation emitted throughout the evolution of relativistic nuclear collisions. We investigate dilepton production from SIS to LHC energies within the off-shell...
The High-Luminosity Large Hadron Collider (HL-LHC) will significantly increase the instantaneous luminosity of the Large Hadron Collider (LHC), requiring major upgrades to the ATLAS detector electronics to ensure reliable data acquisition, detector control, and long-term operational stability. As part of the ATLAS Tile Calorimeter (TileCal) Phase-II upgrade. This contribution presents two...
Technologies developed for high-energy physics (HEP) experiments frequently operate under demanding constraints on sensor size, reliability, cabling, electromagnetic compatibility and remote accessibility. These requirements have driven the development of fibre-optic sensor (FOS) systems for environmental monitoring within the ATLAS experiment at CERN. Many of the same characteristics are...
Trajectum is a relativistic hydrodynamics code, designed to simulate the behaviour of the Quark-Gluon Plasma (QGP) produced during heavy-ion collisions using a hydrodynamic model. Given that the QGP undergoes hadronization as the temperature decreases, a hybrid equation of state (EoS) is required, combining one that is calculated from lattice QCD (LQCD) with one that describes a hadron...
We present a detailed study of transverse momentum broadening for high-energy partons traversing the quark--gluon plasma (QGP), extending the Gyulassy--Levai--Vitev (GLV) formalism to include both all-path-length (APL) corrections and improved sub-Regge kinematics. The standard GLV framework relies on the large separation distance and large formation time approximations, which are well...
High-energy particles are suppressed as they traverse the quark-gluon plasma, but the initial-state contribution to this suppression—or lack thereof—in small systems remains largely unconstrained. We use the saturation-physics-based framework IP-Glasma to predict the nuclear modification factor as a function of centrality in p+Pb, O+O, and Pb+Pb collisions due only to initial-state effects....
Photomultiplier tubes (PMTs) play a critical role in the readout systems of the ATLAS TileCal. They rely on dynode materials with high secondary electron emission (SEE) and radiation tolerance. Secondary electron yields corelate with the electrical conductivity of these dynode materials which are usually extremely high band gap insulators. The conductivity in its turn is dramatically affected...
Identifying rare events with enhanced sensitivity to deconfined quantum chromodynamics (QCD) matter in high-rate heavy-ion experiments requires fast event-selection methods that are robust against detector effects and theoretical model uncertainties. We present a convolutional neural network (CNN) based approach for event-by-event identification of QGP-sensitive collision patterns using...
The multiplicity dependence of heavy-flavour production provides insight into the interplay between soft and hard processes in proton-proton collisions. By studying the relative yield of J/𝜓 as a function of charged-particle multiplicity, the mechanisms governing quarkonium production in events with different levels of activity can be investigated.
This work uses the EPOS4[1] event...
The initial geometry of a heavy-ion collision is determined by the spatial distribution and fluctuations of the participating nucleons. In small collision systems, such as p+Pb, O+O and Ne+Ne, these spatial distributions can have a pronounced influence on the geometry of the produced matter and its subsequent hydrodynamic evolution. While hydrodynamic models have successfully described a wide...
The Tile Calorimeter, a central hadronic calorimeter of the ATLAS experiment at the Large Hadron Collider, is undergoing a major upgrade to meet the requirements of the High-Luminosity LHC (HL-LHC). The Phase-II upgrade aims to address the challenges posed by increased trigger rates of up to 1 MHz, higher radiation levels, and enhanced pile-up conditions through a complete redesign of the...
The path-length dependence of energy loss in the quark-gluon plasma (QGP) has been extensively studied through perturbative quantum chromodynamics (pQCD), where energy is lost through both radiative and collisional processes. Collisional energy loss is expected to scale linearly with the path-length $L$, while radiative energy loss scales as $L^2$, and is known to be the dominant mechanism....
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...
In this talk we shall go through the derivation of the two-loop renormalisation group equations of the five-dimensional MSSM and demonstrate that the power-law mechanism responsible for generating a realistic Higgs mass remains perturbatively consistent once higher-order corrections, KK-resummed contributions, and electroweak precision constraints are taken into account.
We investigate Higgs boson pair production at a future high-energy muon--proton ($\mu^+p$) collider through the charged-current vector-boson-fusion process $\mu^+ p \to \bar{\nu}_\mu\, hh\, j$. Focusing on the $hh\to b\bar{b}b\bar{b}$ decay channel, we consider the characteristic final-state topology comprising four $b$-jets, a forward jet, and missing transverse momentum. The analysis is...
The ALICE experiment investigates the properties of the quark--gluon plasma (QGP) created in ultrarelativistic heavy-ion collisions. Two of the most prominent signatures of QGP formation are the collective hydrodynamic expansion of the produced medium and the energy loss of high-energy partons traversing the medium, known as jet quenching. Measurements performed in high-multiplicity p--Pb and...
Reliable temperature sensing in intense radiation fields remains an important instrumentation challenge across high-energy physics (HEP), accelerator facilities and nuclear systems. In these environments, radiation may not only produce an instantaneous perturbation to an optical sensor, but also alter its underlying calibration and therefore its ability to provide reliable measurements after...
This talk will discuss the recent progress in describing perturbative QCD in event generators.
Many theoretical models predict that Dark Matter (DM) could interact weakly with the Standard Model (SM), thus be produced at the LHC. Many searches have been conducted by the ATLAS experiment to look for DM candidates in the final states with large missing transverse momentum produced in association with other SM particles (light and heavy quarks, leptons, photons, as well as additional heavy...
Muons produced in W-boson and heavy-flavour (HF) hadron decays provide useful information on particle production in proton-proton (pp) collisions. Both mother particles have large masses and are produced in hard-parton scattering in the initial stages of the collision. W-boson studies can probe light-quark parton distribution functions and serve as a baseline for the study of initial-state...
Test submission/acceptance
The ATLAS experiment in the LHC Run 3 uses a two-level trigger system to select events of interest to reduce the 40 MHz bunch crossing rate to a recorded rate of up to 3 kHz of fully-built physics events. The trigger system is composed of a hardware based Level-1 trigger and a software based High Level Trigger. The selection of events by the High Level Trigger is based on a wide variety of...
In this talk, I will briefly review the current status of the world average of the strong coupling constant, as reported by the Particle Data Group. I will then focus on determinations from event shapes and jet rates measured at lepton colliders, highlighting the key outstanding challenges in these measurements and recent developments aimed at resolving them.
The ATLAS experiment at CERN is constructing upgraded system for the "High Luminosity LHC", with collisions due to start in 2030. In order to deliver an order of magnitude more data than previous LHC runs, 14 TeV protons will collide with an instantaneous luminosity of up to 7.5x10e34 cm-2s-1, resulting in much higher pileup and data rates than the current experiment was designed to handle....
Despite the successful structural completion of the Standard Model (SM)
of particle physics through the discovery of the Higgs boson, questions
remain open that cannot be answered within the SM. Among these, two of
the most prominent ones are those for the nature of Dark Matter (DM) and
why there is more matter than antimatter in the universe. The answers to
these (and also other)...
We will present the latest measurements in multiboson and top-quark physics performed by the ATLAS, CMS, and LHCb experiments at the LHC. These measurements cover a broad range of production processes and provide complementary probes of the Standard Model, testing its predictions across different energy scales and interaction regimes. We will review recent experimental results, highlighting...
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 up to 7.5 times the LHC nominal instantaneous luminosity, is expected to begin in 2030. TileCal will require new electronics to meet the requirements of a 1 MHz...
