84 research outputs found
Systematic analysis of the incoming quark energy loss in cold nuclear matter
The investigation into the fast parton energy loss in cold nuclear matter is
crucial for a good understanding of the parton propagation in hot-dense medium.
By means of four typical sets of nuclear parton distributions and three
parametrizations of quark energy loss, the parameter values in quark energy
loss expressions are determined from a leading order statistical analysis of
the existing experimental data on nuclear Drell-Yan differential cross section
ratio as a function of the quark momentum fraction. It is found that with
independence on the nuclear modification of parton distributions, the available
experimental data from lower incident beam energy rule out the incident-parton
momentum fraction quark energy loss. Whether the quark energy loss is linear or
quadratic with the path length is not discriminated. The global fit of all
selected data gives the quark energy loss per unit path length {\alpha} =
1.21\pm0.09 GeV/fm by using nuclear parton distribution functions determined
only by means of the world data on nuclear structure function. Our result does
not support the theoretical prediction: the energy loss of an outgoing quark is
three times larger than that of an incoming quark approaching the nuclear
medium. It is desirable that the present work can provide useful reference for
the Fermilab E906/SeaQuest experiment
Quark energy loss and shadowing in nuclear Drell-Yan process
The energy loss effect in nuclear matter is another nuclear effect apart from
the nuclear effects on the parton distribution as in deep inelastic scattering
process. The quark energy loss can be measured best by the nuclear dependence
of the high energy nuclear Drell-Yan process. By means of three kinds of quark
energy loss parameterizations given in literature and the nuclear parton
distribution extracted only with lepton-nucleus deep inelastic scattering
experimental data, measured Drell-Yan production cross sections are analyzed
for 800GeV proton incident on a variety of nuclear targets from FNAL E866. It
is shown that our results with considering the energy loss effect are much
different from these of the FNAL E866 who analysis the experimental data with
the nuclear parton distribution functions obtained by using the deep inelastic
lA collisions and pA nuclear Drell-Yan data . Considering the existence of
energy loss effect in Drell-Yan lepton pairs production,we suggest that the
extraction of nuclear parton distribution functions should not include
Drell-Yan experimental data.Comment: 12 page
Bjorken variable and scale dependence of quark transport coefficient in semi-inclusive lepton-production of hadron off nuclei
Nuclear modification of hadron production in deep inelastic lepton-nucleus
scattering can be applied to study the parton propagation mechanism in cold
nuclear matter. By means of the analytic parameterization of quenching weight
based on BDMPS formalism with the target nuclear geometry effect, the
leading-order computations for hadron multiplicity ratios are performed with
comparison to the HERMES charged pions production data on the quarks
hadronization occurring outside the nucleus. The relation is discovered between
quark transport coefficient and the measurable kinematic variables in deep
inelastic scattering. Four models are proposed on the quark transport
coefficient. The constant model, the power-law model and the double power-law
model can be ruled out because of the experimental fact that the transverse
momentum broadening increases as a function of the photon virtuality . The
quark transport coefficient is determined as a function of the Bjorken variable
and scale . The trend of quark transport coefficient in respect of
Bjorken variable and scale is qualitatively in partial agreement with
HERMES experimental data on transverse momentum broadening. It is hoped that
our effort is conducive to understanding of jet quenching phenomenon in
relativistic heavy ion collisions
Nuclear geometry effect and transport coefficient in semi-inclusive lepton-production of hadrons off nuclei
Hadron production in semi-inclusive deep-inelastic scattering of leptons from
nuclei is an ideal tool to determine and constrain the transport coefficient in
cold nuclear matter. The leading-order computations for hadron multiplicity
ratios are performed by means of the SW quenching weights and the analytic
parameterizations of quenching weights based on BDMPS formalism. The
theoretical results are compared to the HERMES positively charged pions
production data with the quarks hadronization occurring outside the nucleus.
With considering the nuclear geometry effect on hadron production, our
predictions are in good agreement with the experimental measurements. The
extracted transport parameter from the global fit is shown to be for the SW quenching weight without the finite energy
corrections. As for the analytic parameterization of BDMPS quenching weight
without the quark energy E dependence, the computed transport coefficient is
. It is found that the nuclear geometry effect
has a significant impact on the transport coefficient in cold nuclear matter.
It is necessary to consider the detailed nuclear geometry in studying the
semi-inclusive hadron production in deep inelastic scattering on nuclear
targets.Comment: 14 pages, 3 figures. arXiv admin note: text overlap with
arXiv:1310.569
Triple-product asymmetry in the radiative two-pion tau decay
In this work, we perform a detailed study of the
decay process within the resonance chiral
theory. We pay special attention to the triple-product asymmetry in the
process. The minimal resonance chiral Lagrangian
and the odd-intrinsic parity resonance operators are simultaneously included to
calculate the decay amplitudes. Various invariant-mass distributions in the
, and systems are studied and they
reveal different resonance dynamics. We further predict the intriguing nonzero
triple-product asymmetry distributions, which may provide useful guidelines for
future experimental measurements conducted at the Belle-II and super tau-charm
facilities.Comment: 32 pages, 9 figures. To match the published versio
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