Mesons In Jets Research Articles

Longitudinal momentum fraction of heavy-flavor mesons in jets in high-energy nuclear collisions

Longitudinal momentum fraction of heavy-flavor mesons in jets in high-energy nuclear collisions

Radial profile of bottom quarks in jets in high-energy nuclear collisions * *Supported by the Guangdong Major Project of Basic and Applied Basic Research (2020B0301030008), the Science and Technology Program of Guangzhou (2019050001) and the NSFC of China with Project (11935007, 11805167)

Angular correlations between a heavy quark (HQ) and its tagged jet are potentially new tools to gain insight into the in-medium partonic interactions in relativistic heavy-ion collisions. In this work, we present the first theoretical study on the radial profiles of B mesons in jets in Pb+Pb collisions at the Large Hadron Collider (LHC). The initial production of a bottom quark tagged jet in p+p is computed by SHERPA, which matches the next-to-leading order matrix elements with contributions of parton showers, whereas the massive quark traversing the quark-gluon plasma is described by a Monte Carlo model, SHELL, which can simultaneously simulate light and heavy flavor in-medium energy loss within the framework of Langevin evolution. In p+p collisions, we find that at lower the radial profiles of heavy flavors in jets are sensitive to the heavy quark mass. In 0-10% Pb+Pb collisions at TeV, we observe an inverse modification pattern of the B meson radial profiles in jets at GeV compared to those of D mesons: the jet quenching effects narrow the jet radial profiles of B mesons in jets while broadening those of D mesons in jets. We find that in A+A collisions, the contribution dissipated from the higher GeV region naturally has a narrower initial distribution and consequently leads to a narrower modification pattern of the radial profile; however the diffusion nature of the heavy flavor in-medium interactions will give rise to a broader modification pattern of the radial profile. These two effects consequently compete and offset with each other, and the b quarks in jets benefit more from the former and suffer less diffusion effect compared to that of c quarks in jets. These findings can be tested in the future experimental measurements at the LHC to gain better understanding of the mass effect of jet quenching.

Study of J/ψ Production in Jets.

The production of J/ψ mesons in jets is studied in the forward region of proton-proton collisions using data collected with the LHCb detector at a center-of-mass energy of 13TeV. The fraction of the jet transverse momentum carried by the J/ψ meson, z(J/ψ)≡p_{T}(J/ψ)/p_{T}(jet), is measured using jets with p_{T}(jet)>20 GeV in the pseudorapidity range 2.5<η(jet)<4.0. The observed z(J/ψ) distribution for J/ψ mesons produced in b-hadron decays is consistent with expectations. However, the results for prompt J/ψ production do not agree with predictions based on fixed-order nonrelativistic QCD. This is the first measurement of the p_{T} fraction carried by prompt J/ψ mesons in jets at any experiment.

Charm content in jets in proton-proton collisions with the ALICE experiment at CERN-LHC

Charm and bottom quarks have been proposed as probes to study partonic matter produced in high-energy heavy-ion collisions. The detailed understanding of the production mechanisms in proton-proton collisions is of considerable interest as a QCD test tool and as reference calibration for heavy-ion studies. Measurements of the D meson yield in jets probe the production processes in which the observed D mesons are formed primarily from gluon splitting into cc̄ or bb̄ pairs. The charm content in jets is calculable in perturbative QCD, and the leading non-perturbative correction is expected to be significant at LHC energies. In this contribution we present a performance study of the reconstruction of charged D*± mesons in jets based on the first data collected by the ALICE experiment in minimum bias p+p collisions at = 7 TeV . D*+ mesons are reconstructed through the decay sequence D*+ → D0π+ and D0 → K−π+ (and its charge conjugate channel).

Measurement of D production in jets from p-barp collisions at sqrt s =1.8 TeV.

The production rate of charged {ital D}{sup *} mesons in jets has been measured in 1.8-TeV {ital {bar p}p} collisions at the Fermilab Tevatron with the Collider Detector at Fermilab. In a sample of approximately 32 300 jets with a mean transverse energy of 47 GeV obtained from an exposure of 21.1 nb{sup {minus}1}, a signal corresponding to 25.0{plus minus}7.5(stat){plus minus}2.0(syst) {ital D}{sup *{plus minus}}{r arrow}K{sup {minus plus}}{pi}{sup {plus minus}}{pi}{sup {plus minus}} events is seen above background. This corresponds to a ratio {ital N}({ital D}{sup *+}+D{sup *{minus}})/N(jet) =0.10{plus minus}0.03{plus minus}0.03 for {ital D}{sup *} mesons with fractional momentum {ital z} greater than 0.1.

A Monte-Carlo calculation of the production spectrum of mesons in jets

A sample of 200 values of the momentum of the secondaries in high-energy meson jets has been computed by means of a Monte-Carlo procedure, starting from experimental observed facts such as the Gaussian distribution of log p T and the isotropy in the emitting centre system. The shape of the spectrum of p-values does not agree with d p/ p 2.