Conveners
Hot and dense matter physics - QGP and heavy ion collisions
- Dennis Perepelitsa (University of Colorado Boulder)
- Guilherme Milhano (LIP)
- Leticia Cunqueiro (ORNL)
Hot and dense matter physics - QGP and heavy ion collisions
- Leticia Cunqueiro (ORNL)
- Dennis Perepelitsa (University of Colorado Boulder)
- Guilherme Milhano (LIP)
Jets emerging from heavy-flavour quark fragmentation represent convenient benchmark probes for perturbative quantum chromodynamics and heavy-flavour fragmentation models. In contrast to light-flavour jets, heavy-flavour jet substructure should be affected by the dead cone effect which suppresses collinear gluon emission off a heavy-flavour quark radiator. This phenomenon may affect also cold...
Ultra-relativistic heavy-ion collisions have unlocked the study of a hot, dense state of QCD matter, the Quark-Gluon Plasma (QGP). However, due to its short lifetime, on the yoctosecond scale, the QGP must be studied with recourse to external probes, such as jets, collimated sprays of particles originated from the hard scattering.
Since jets are multi-scale probes, we can use jet quenching,...
Interactions of high-$p_{\rm{T}}$ partons with quark-gluon plasma (QGP) result in jet quenching, which is manifest by the suppression of high-$p_{\rm{T}}$ jet yields and the modification of jet substructure and di-jet acoplanarity distributions. Several jet quenching phenomena can be measured precisely over a wide range of jet $p_{\rm{T}}$ using semi-inclusive distributions of charged jets...
Over the last decades, analytical calculations of jet quenching observables were force to always make a distinction between jet evolution in dense or dilute mediums. Although there are different theoretical formalisms suited for each one of these scenarios, taking into account multiple soft and single hard interactions between the probe and the background under a single approach has proven to...
An important aspect of the study of Quark-Gluon Plasma (QGP) in ultra-relativistic collisions of heavy ions is the ability to identify a subset of jets that were strongly modified by the interaction with the QGP. In this talk, we will show how deep learning techniques can be applied for this purpose. Samples of $Z+$jet events were simulated in vacuum and medium and used to train deep neural...
This talk gives an overview of the latest hard process measurements in heavy ion collision systems with the ATLAS detector at the LHC, utilizing the high statistics 5.02 TeV Pb+Pb data collected in 2018. These include multiple measurements of jet production and structure, which probe the dynamics of the hot, dense Quark-Gluon Plasma formed in relativistic nucleus-nucleus collisions;...
Jet interactions in a hot QCD medium created in heavy-ion collisions are conventionally assessed by measuring the modification of the distributions of jet observables with respect to the proton-proton baseline. However, the steeply falling production spectrum introduces a strong bias toward small energy losses that obfuscates a direct interpretation of the impact of medium effects in the...
Medium-induced gluon radiation is known to be an important tool to extract the properties of the QGP created in heavy-ion collisions. I will use a recent approach to evaluate the full in-medium gluon emission spectrum, including the resummation of all multiple scatterings, to analyze the validity of the usually employed analytical approximations. More specifically, by using this all-order...
We calculate the resummed perturbative free energy of ${\cal N}=4$ supersymmetric Yang-Mills in four spacetime dimensions through second order in the 't Hooft coupling $\lambda$ at finite temperature and zero chemical potential. Our final result is ultraviolet finite and all infrared divergences generated at three-loop level are canceled by summing over ${\cal N}=4$ supersymmetric Yang-Mills...
The phase transition from hadronic material to quark-gluon plasma (QGP) is a phenomenon that occurs under extreme conditions of high temperature and high density. The QGP causes energy loss of high momentum particles which is observed as a suppression of high momentum hadron production in A+A collisions relative to p+p collisions. PHENIX, one of the relativistic heavy ion collider (RHIC)...
The High Acceptance DiElectron Spectrometer (HADES) is dedicated to the measurement of electromagnetic probes from heavy ion collisions and to study the in-medium behaviour of dileptons in the moderate temperature and high density regime of the QCD phase diagram. The spectral distributions of dileptons reveal the thermal properties of the medium. With the recent upgrade of the HADES RICH...
NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) is a fixed target experiment located at the CERN SPS. Its strong interactions programme is devoted to study properties of the phase diagram of strongly interacting matter. For this goal the two-dimensional scan is performed by measurements of hadron production properties as a function of collision energy (13A - 158A GeV/c) and system size...
Finite magnetic field is relevant for both systems where QCD matter can be studied in practice - heavy ion collisions and neutron stars. It was shown recently, that in sufficiently strong magnetic fields and at moderate baryon densities a new phase of QCD matter appears: a crystalline condensate of neutral pions named the chiral soliton lattice. This phase might be relevant for magnetars;...
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Despite being the overwhelming majority of events produced in hadron or heavy ion collisions, minimum bias events do not enjoy a robust first-principles theoretical description as their dynamics are dominated by low-energy quantum chromodynamics. In this talk I will present a novel expansion scheme of the cross section for minimum bias events that exploits an ergodic hypothesis for particles...
Electroweak-boson production in hadronic processes is a clean tool for the investigation of the parton distribution functions (PDFs). This is especially true in heavy-ion collisions at the LHC, where the initial state is still poorly constrained by measurements and important for the interpretation of the system evolution. The ALICE experiment can measure W and Z bosons via their leptonic...
This talk gives an overview of the latest ultra-peripheral physics measurements performed with the ATLAS detector at the LHC. These include differential measurements of the exclusive di-muon production cross-section, which are crucial for setting constraints on the initial photon spectrum for all UPC measurements at the LHC; measurements of light-by-light scattering, which result in an...
Produced only in hard-scattering processes occurring in the initial stage of the collisions, heavy quarks offer a unique perspective to study the transition from quarks to hadrons in all collision systems. Recently, the ALICE experiment at the LHC measured the $\Lambda_{\rm c}^{+}$, $\Xi_{\rm c}^{0}$, $\Xi_{\rm c}^{+}$, and $\Sigma_{\rm c}^{0,++}$ charmed-baryon $p_{\rm T}$-differential cross...
Waiting for abstract.
The study of heavy quarkonium suppression in heavy-ion collisions represents an important source of information about the properties of the quark-gluon plasma produced in such collisions. The evolution of the reduced density matrix of heavy quarks inside a quark-gluon plasma is described by a master equation. In a previous work, we found that this master equation needs to take into account the...
One of main goals of the STAR experiment is to study the Quark-Gluon Plasma (QGP) produced in ultra-relativistic heavy-ion collisions. Charm quarks are an ideal probe of the QGP, as they are created primarily in hard partonic scatterings at early stage of Au+Au collisions. In this talk, we present the measurements of $D^{\pm}$ meson production in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200...
Resonances with very short lifetimes can be used to probe the rescattering and regeneration ~ processes in the hadronic phase of the system produced after a high-energy collisions. These processes are studied by measuring resonance yields as a function of the system size and collision energy and comparing them to model calculations with and without the hadronic cascades. We present...
Exclusive photoproduction of Ï0(770) mesons is studied using the H1 detector at the ep collider HERA. A sample of about 900000 events is used to measure single- and double-differential cross sections for the reaction $\gamma p\to\pi^{+}\pi^{-}Y$. Reactions where the proton
stays intact ($m_Y=m_p$) are statistically separated from those where the proton dissociates to a low-mass hadronic...
This talk gives an overview of the latest measurements of collective behavior in a variety of collision systems with the ATLAS detector at the LHC, including pp collisions at 13 TeV, Xe+Xe collisions at 5.44 TeV, and Pb+Pb collisions at 5.02 TeV. These include measurements of vn-[pT] correlations in Xe+Xe and Pb+Pb, which carry important information about the initial-state geometry of the...
Measurements of two- and multiparticle azimuthal correlations provide valuable information on the properties of the quark--gluon plasma. In this talk, the latest results for inclusive and identified charged particle azimuthal correlations are reported in Pb--Pb and Xe--Xe collisions recorded by the ALICE detector. These results provide strong constraints on the initial conditions of a...
