The radial distribution of
D
0
mesons in jets probes the diffusion of charm quark relative to the jet axis and provides a new perspective to study the interaction mechanisms between heavy quarks and ...the medium in the nucleus-nucleus collisions. The in-medium parton propagations are described by a Monte Carlo transport model which uses the next-to-leading order (NLO) plus parton shower (PS) event generator SHERPA as input and includes elastic (collisional) and inelastic (radiative) interaction for heavy quarks as well as light partons. At low
D
0
meson
p
T
, the radial distribution significantly shifts to larger radius indicating a strong diffusion effect which is consistent with the recent experimental data. We demonstrate that the angular deviation of charm quarks declines with
p
T
and is very sensitive to the collisional more than radiative interaction at
p
T
<
5
GeV. As predictions, we present the
D
0
meson radial distribution in jets in p + p and
0
-
10
%
Au + Au collisions at
s
NN
=
200
GeV at the RHIC, and also estimate the nuclear modification factor of charm jet in central Au + Au collisions at 200 GeV at the RHIC and central Pb + Pb collisions at 5.02 TeV at the LHC.
In collisions of ultrarelativistic nuclei, photon-tagged jets provide a unique opportunity to compare jet production and modification due to parton shower formation and propagation in strongly ...interacting matter at vastly different center-of-mass energies. We present first results for the cross sections of jets tagged by an isolated photon to O(α(em)α(s)(2)) in central Au+Au reactions with sqrts(NN) = 200 GeV at RHIC and central Pb + Pb reactions with sqrts(NN) = 2.76 TeV at LHC. We evaluate the increase in the transverse momentum imbalance of the observed γ + jet state, induced by the dissipation of the parton shower energy due to strong final-state interactions. Theoretical predictions to help interpret recent and upcoming experimental data are presented.
We investigate the flavor dependence of jet quenching, by performing a systematic analysis of medium modifications on the inclusive jet, γ+jet, and b-jet in Pb+Pb collisions at the LHC. Our results ...from MadGraph+PYTHIA exhibit excellent agreement with experimental measurements of the inclusive jet, γ+jet and b-jet simultaneously in p+p collisions. We then utilize a Bayesian data-driven method to extract systematically the flavor-dependent jet energy loss distributions from experimental data, where the gluon, light quark and b-quark initiated energy loss distributions are well constrained and satisfy the predicted flavor hierarchy of jet quenching, i.e. 〈ΔEg〉>〈ΔEq〉>〈ΔEb〉. It is shown that the quark-initiated jet energy loss distribution shows weaker centrality and pT dependence than the gluon-initiated one. We demonstrate the impacts of the slope of initial spectra, color-charge as well as parton mass dependent jet energy attenuation on the γ/b-jet suppression observed in heavy-ion collisions.
We demonstrate that jet observables are highly sensitive to the characteristics of the vacuum and the in-medium QCD parton showers and propose techniques that exploit this sensitivity to constrain ...the mechanism of quark and gluon energy loss in strongly interacting plasmas. As a first example, we calculate the inclusive jet cross section in high-energy nucleus-nucleus collisions to O(alpha(s)(3)). Theoretical predictions for the medium-induced jet broadening and the suppression of the jet production rate due to cold and hot nuclear matter effects in Au+Au and Cu+Cu reactions at RHIC are presented.
The Seebeck effect and the Nernst effect, which reflect the appearance of electric fields along
x
-axis and along
y
-axis (
E
x
and
E
y
), respectively, induced by the thermal gradient along
x
-axis, ...are studied in the QGP at an external magnetic field along
z
-axis. We calculate the associated Seebeck coefficient (
S
xx
) and Nernst signal (
N
) using the relativistic Boltzmann equation under the relaxation time approximation. In an isotropic QGP, the influences of magnetic field (
B
) and quark chemical potential (
μ
q
) on these thermoelectric transport coefficients are investigated. In the presence (absence) of weak magnetic field, we find
S
xx
for a fixed
μ
q
is negative (positive) in sign, indicating that the dominant carriers for converting heat gradient to electric field are negatively (positively) charged quarks. The absolute value of
S
xx
decreases with increasing temperature. Unlike
S
xx
, the sign of
N
is independent of charge carrier type, and its thermal behavior displays a peak structure. In the presence of strong magnetic field, due to the Landau quantization of transverse motion of (anti-)quarks perpendicular to magnetic field, only the longitudinal Seebeck coefficient (
S
zz
) exists. Our results show that the value of
S
zz
at a fixed
μ
q
in the lowest Landau level (LLL) approximation always remains positive. Within the effect of high Landau levels,
S
zz
exhibits a thermal structure similar to that in the LLL approximation. As the Landau level increases further,
S
zz
decreases and even its sign changes from positive to negative. The computations of these thermoelectric transport coefficients are also extended to a medium with momentum-anisotropy induced by initial spatial expansion as well as strong magnetic field.
In this work, we pave the way to calculate the productions of
ω
and
K
S
0
mesons with large
p
T
in p+p and A+A collisions both at RHIC and LHC. The fragmentation functions (FFs) of the
ω
meson in ...vacuum at next-to-leading order (NLO) are obtained by evolving the NLO DGLAP evolution equations with rescaled
ω
FFs at initial scale
Q
0
2
=
1.5
GeV
2
from a broken SU(3) model, and the FFs of
K
S
0
in vacuum are taken from AKK08 parametrization directly. Within the framework of the NLO pQCD improved parton model, we arrive at good descriptions of the experimental data on
ω
and
K
S
0
in p+p both at RHIC and LHC. With the higher-twist approach, to take into account jet quenching effect by medium-modified FFs, nuclear modification factors for
ω
meson and
K
S
0
meson both at RHIC and LHC are presented with different sets of jet transport coefficients
q
^
0
. Then we make a global extraction of
q
^
0
both at RHIC and LHC by confronting our model calculations with all available data on six identified mesons:
π
0
,
η
,
ρ
0
,
ϕ
,
ω
, and
K
S
0
. The minimum value of total
χ
2
/
d
.
o
.
f
for productions of these mesons gives the best value of
q
^
0
=
0.5
G
e
V
2
/
f
m
for Au+Au collisions with
s
NN
=
200
GeV at RHIC, and
q
^
0
=
1.2
G
e
V
2
/
f
m
for Pb+Pb collisions with
s
NN
=
2.76
TeV at LHC, respectively, with the QGP spacetime evolution given by the event-by-event viscous hydrodynamics model IEBE-VISHNU. With these global extracted values of
q
^
0
, nuclear modification factors of
π
0
,
η
,
ρ
0
,
ϕ
,
ω
, and
K
S
0
in A+A collisions are presented, and predictions of yield ratios such as
ω
/
π
0
and
K
S
0
/
π
0
at the high-
p
T
regime in heavy-ion collisions both at RHIC and LHC are provided.
We carry out the first theoretical investigation on yields and the hardest parton splitting of large-radius jets reclustered from small radius (
R
=
0.2
) anti-
k
t
jets in Pb + Pb collisions, and ...confront them with the recent ATLAS measurements. The Linear Boltzmann Transport (LBT) model is employed for jet propagation and jet-induced medium excitation in the hot-dense medium. We demonstrate that, with their complex structures, the medium suppression of the reclustered large radius jets at
R
=
1
is larger than that of inclusive
R
=
0.4
jets defined conventionally. The large radius jet constituents are reclustered with the
k
t
algorithm to obtain the splitting scale
d
12
, which characterizes the transverse momentum scale for the hardest splitting in the jet. The large-radius jet production as a function of the splitting scale
d
12
of the hardest parton splitting is overall suppressed in Pb + Pb relative to p + p collisions due to the reduction of jets yields. A detailed analyses show that the alterations of jet substructures in Pb + Pb also make significant contribution to the splitting scale
d
12
dependence of the nuclear modification factor
R
AA
. Numerical results for the medium modifications of the jet splitting angle
Δ
R
12
and the splitting fraction
z
are also presented.
Within the framework of the generalized QCD factorization formalism, a set of nuclear-dependent observables all arise from the quark-gluon and gluon-gluon correlation functions, which are closely ...connected to the well-known jet transport coefficient ( ^ q ) for the nucleus. In this paper, we perform the first global analysis of ^ q for cold nuclear matter with a kinematics dependent parametrization. The analysis takes into account the world data on transverse momentum broadening in semi-inclusive electron-nucleus deep inelastic scattering, Drell-Yan dilepton and heavy quarkonium production in proton-nucleus collisions, as well as the nuclear modification of the structure functions in deep inelastic scattering, comprising a total of 215 data points from 8 datasets. Within our scheme, we clarify quantitatively the universality and kinematics dependence of the nuclear medium property as encoded in ^ q . We expect that the determined parametrization of ^ q in cold nuclear matter will have significant impact on precise identification of the transport property of hot dense medium created in heavy ion collisions.
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