Search results for "Collisions"

Relative particle yield fluctuations in Pb--Pb collisions at √sNN = 2.76 TeV

2019

First results on K/π, p/π and K/p fluctuations are obtained with the ALICE detector at the CERN LHC as a function of centrality in Pb–Pb collisions at √sNN = 2.76 TeV. The observable νdyn, which is defined in terms of the moments of particle multiplicity distributions, is used to quantify the magnitude of dynamical fluctuations of relative particle yields and also provides insight into the correlation between particle pairs. This study is based on a novel experimental technique, called the Identity Method, which allows one to measure the moments of multiplicity distributions in case of incomplete particle identification. The results for p/π show a change of sign in νdyn from positive to neg…

Measurement of two-particle correlations with respect to second- and third-order event planes in Au+Au collisions at √sNN = 200 GeV

2019

We present measurements of azimuthal correlations of charged hadron pairs in √sNN = 200 GeV Au + Au collisions for the trigger and associated particle transverse-momentum ranges of 1 4 GeV/c) correlations is suppressed compared with that of correlations measured in p + p collisions. At the lowest associated particle pT (0.5 < pa T < 1 GeV/c), the away-side shape and yield are modified relative to those in p + p collisions. These observations are consistent with the scenario of radiative-jet energy loss. For the low-pT trigger correlations (2 < pt T < 4 GeV/c), a finite away-side yield exists and we explore the dependence of the shape of the away-side within the context of an underlying-even…

Multiparticle azimuthal correlations for extracting event-by-event elliptic and triangular flow in Au + Au collisions at √sNN = 200 GeV

2019

Jet-like correlations with neutral pion triggers in pp and central Pb–Pb collisions at 2.76 TeV

2016

Physics letters / B B763, 238 - 250 (2016). doi:10.1016/j.physletb.2016.10.048

Flow dominance and factorization of transverse momentum correlations in Pb-Pb collisions at the LHC

2017

Physical review letters 118(16), 162302 (2017). doi:10.1103/PhysRevLett.118.162302

Features of W production in p-p, p-Pb and Pb-Pb collisions

2017

We consider the production of inclusive W bosons in variety of high-energy hadronic collisions: p--p, p--$\overline{\rm p}$, p--Pb, and Pb--Pb. In particular, we focus on the resulting distributions of charged leptons from W decay that can be measured with relatively low backgrounds. The leading-order expressions within the collinearly factorized QCD indicate that the center-of-mass energy dependence at forward/backward rapidities should be well approximated by a simple power law. The scaling exponent is related to the small-$x$ behaviour of the quark distributions, which is largely driven by the parton evolution. An interesting consequence is the simple scaling law for the lepton charge as…

First measurement of the |t|-dependence of coherent J/ψ photonuclear production

2021

The first measurement of the dependence on $|t|$, the square of the momentum transferred between the incoming and outgoing target nucleus, of coherent J/ψ photoproduction is presented. The data were measured with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} = 5.02$ TeV with the J/$\psi$ produced in the central rapidity region $|y| < 0.8$, which corresponds to the small Bjorken-$x$ range $(0.3 − 1.4) \times 10 ^{−3}$. The measured $|t|$-dependence is not described by computations based only on the Pb nuclear form factor, while the photonuclear cross section is better reproduced by models including shadowing according t…

D-meson production in p-Pb collisions at √sNN = 5.02 TeV and in pp collisions at √s = 7 TeV

2016

Background: In the context of the investigation of the quark gluon plasma produced in heavy-ion collisions, hadrons containing heavy (charm or beauty) quarks play a special role for the characterization of the hot and dense medium created in the interaction. The measurement of the production of charm and beauty hadrons in proton– proton collisions, besides providing the necessary reference for the studies in heavy-ion reactions, constitutes an important test of perturbative quantum chromodynamics (pQCD) calculations. Heavy-flavor production in proton–nucleus collisions is sensitive to the various effects related to the presence of nuclei in the colliding system, commonly denoted cold-nuclea…

Forward J/ψ production in pA collisions : centrality dependence

2016

The nuclear suppression of forward J/ψ production in high energy proton-nucleus collisions can be used as a probe of gluon saturation at small x. In an earlier work we studied this suppression in minimum bias collisions in the Color Glass Condensate formalism, relying on the optical Glauber model to obtain the dipole cross section of the nucleus from the one of the proton fitted to HERA DIS data. Here we study how the impact parameter dependence of this model can be used to compare our results with recent LHC data on the centrality dependence of this suppression. peerReviewed

Review of Particle Physics

2020

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,143 new measurements from 709 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, …