Search results for "gluonit"
showing 7 items of 7 documents
Success and challenges of flow harmonic analysis in LHC collisions from large to small systems
2022
One of the primary goals of heavy-ion physics is to understand the transport properties of the quark-gluon-plasma (QGP) which comprises the tiniest constituents, quarks and gluons, that prevailed in the first few microseconds after the Big Bang. The present most challenging part of the research is pinning down the critical point of the QGP, where the shear viscosity over entropy ratio (η/s) is at its minimum and very close to the lowest value in nature 1/(4π). Significant advances based on flow harmonic analysis have been made up to date. However, there are still few remaining challenges in experiments and theory to constrain the temperature dependence of η/s and ζ/s of the QGP. In this tal…
A Monte Carlo simulation for the elastic energy loss of high-energy partons in a strongly interacting medium
2012
New Constraints of QCD Matter from Bayesian Parameter Estimation with LHC Data
2022
New constraints of QCD matter from improved Bayesian parameter estimation with the latest LHC data
2022
Transport properties of the matter created in heavy-ion collisions, the quark-gluon plasma (QGP), contain essential information about quantum chromodynamics (QCD). In this talk, we present our latest study in inferring the transport properties of QGP by an improved Bayesian analysis using the CERN Large Hadron Collider Pb-Pb data. The uncertainties of the extracted properties are reduced by adding new observables sensitive to specific shear and bulk viscosity, reflecting mostly nonlinear hydrodynamic responses. The analysis also reveals that higher-order harmonic flows and their correlations have a higher sensitivity to the transport properties than other observables. This observation shows…
Numerical evaluation of the nonlinear Gribov-Levin-Ryskin-Mueller-Qiu evolution equations for nuclear parton distribution functions
2023
We numerically study for the first time the nonlinear GLR-MQ evolution equations for nuclear parton distribution function (nPDFs) to next-to-leading order accuracy and quantify the impact of gluon recombination at small $x$. Using the nCTEQ15 nPDFs as input, we confirm the importance of the nonlinear corrections for small $x \lesssim 10^{-3}$, whose magnitude increases with a decrease of $x$ and an increase of the atomic number $A$. We find that at $x=10^{-5}$ and for heavy nuclei, after the upward evolution from $Q_0=2$ GeV to $Q=10$ GeV, the quark singlet $\Omega(x,Q^2)$ and the gluon $G(x,Q^2)$ distributions become reduced by $9-15$%, respectively. The relative effect is much stronger fo…
Nuclear gluons at RHIC in a multi-observable approach
2019
We explore the possibility of measuring nuclear gluon distributions at the Relativistic Heavy-Ion Collider (RHIC) with $\sqrt{s}=200 \, {\rm GeV}$ proton-nucleus collisions. In addition to measurements at central rapidity, we consider also observables at forward rapidity, consistent with proposed upgrades to the experimental capabilities of STAR and sPHENIX. The processes we consider consist of Drell-Yan dilepton, dijet, and direct photon-jet production. The Drell-Yan process is found to be an efficient probe of gluons at small momentum fractions. In order to fully utilize the potential of Drell-Yan measurements we demonstrate how the overall normalization uncertainty present in the experim…
Diffractive Processes at Next-to-Leading Order in the Dipole Picture
2023
Diffraktiiviset prosessit ovat korkean energian rajalla sensitiivisiä kohdehiukkasen gluonijakaumalle, mistä johtuen niiden avulla voidaan tutkia kohdetta kvanttiväridynamiikan epälineaarisessa alueessa. Näiden epälineaaristen ilmiöiden odotetaan johtavan gluonisaturaatioon, jota voidaan kuvata luontevasti värilasikondensaatiksi kutsutun efektiivisen kenttäteorian avulla. Vaikka saatavilla olevassa kokeellisessa datassa onkin vahvoja viitteitä gluonisaturaatiosta, yksiselitteistä merkkiä saturaatiosta ei ole havaittu. Tämän vuoksi on tärkeää parantaa saturaatiolle sensitiivisten prosessien teoreettista ymmärrystä, jotta pystytään löytämään selkeitä eroja kvanttiväridynamiikan lineaarisen ja…