This talk presents a new measurement studying the relationship between the production of hard and soft particles through the correlation of Upsilon meson states with the inclusive-charged particle yields in 13 TeV pp collisions. Measurements are made differentially for Upsilon momentum and for different Upsilon states. The analysis is performed using the full-luminosity ATLAS Run-2 13 TeV pp...
The Multiplicity fluctuations are sensitive to QCD phase transition and to the presence of of critical point in QCD phase diagram. 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 ...
The interpretation of measurements from high energy collisions at experiments like the Large Hadron Collider (LHC) relies heavily on the performance of full event generators, specifically their accuracy and speed in simulating complex multi-particle final states. With the rapid and continuous improvement in quantum computers, these devices present an exciting opportunity for high energy...
The elastic scattering of protons at 13 TeV is measured in the range of protons transverse momenta allowing the access to the Coulomb-Nuclear-Interference region. The data were collected thanks to dedicated special LHC beta* = 2.5km optics. The total cross section as well as rho-parameter, the ratio of the real to imaginary part of the forward elastic scattering amplitude, are measured and...
The factorization hypothesis states that the production cross-section of heavy-flavor hadrons can be calculated as the convolution of three independent terms: the parton distribution function of the colliding hadrons, the production cross sections of the heavy-quarks in the hard partonic process, and finally the fragmentation functions of the heavy-flavor quarks into the given heavy-flavor...
Mass ordering is expected for energy loss of quarks traversing the quark gluon plasma (QGP). Gluon bremsstrahlung is the dominant mechanism for light quark energy loss; however, both radiative and collisional energy loss must be considered for heavy quarks. At low transverse momentum these mechanisms have significant quark mass dependence. Therefore, separated charm and beauty measurements are...
Cross-section measurements for a Z boson produced in association with high-transverse-momentum jets (pT > 100 GeV) and decaying into a charged-lepton pair are presented. The measurements are performed using proton-proton collisions at sort(s) = 13 TeV corresponding to an integrated luminosity of 139 fb^-1 collected by the ATLAS experiment at the LHC. Measurements of angular correlations...
Time-Like Compton Scattering (TCS) is a hard, exclusive process, involving the elastic scattering of a real photon from a nucleon, and the production of a virtual photon that decays to a heavy lepton pair in the final state. Studies of TCS observables are used to broaden our understanding of Generalised Parton Distributions (GPD’s) which can offer insights into the internal structure of the...
Measurements of jet production 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. Recent studies of high-multiplicity final states of small collision systems exhibit signatures of collective effects that could be associated with hot and dense, color-deconfined QCD matter,...
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...
