3,050 research outputs found
The role of finite kinematic bounds in the induced gluon emission from fast quarks in a finite size quark-gluon plasma
We study the influence of finite kinematic boundaries on the induced gluon
radiation from a fast quark in a finite size quark-gluon plasma. The
calculations are carried out for fixed and running coupling constant. We find
that for running coupling constant the kinematic correction to the radiative
energy loss is small for quark energy larger than about 5 GeV. Our results
differ both analytically and numerically from that obtained by the GLV group
[6]. The effect of the kinematic cut-offs is considerably smaller than reported
in [6].Comment: 11 pages, 4 figure
Anomalous mass dependence of radiative quark energy loss in a finite-size quark-gluon plasma
We demonstrate that for a finite-size quark-gluon plasma the induced gluon
radiation from heavy quarks is stronger than that for light quarks when the
gluon formation length becomes comparable with (or exceeds) the size of the
plasma. The effect is due to oscillations of the light-cone wave function for
the in-medium transition. The dead cone model by Dokshitzer and
Kharzeev neglecting quantum finite-size effects is not valid in this regime.
The finite-size effects also enhance the photon emission from heavy quarks.Comment: 8 pages, 3 figure
Induced photon emission from quark jets in ultrarelativistic heavy-ion collisions
We study the induced photon bremsstrahlung from a fast quark produced in
AA-collisions due to multiple scattering in quark-gluon plasma. For RHIC and
LHC conditions the induced photon spectrum is sharply peaked at photon energy
close to the initial quark energy. In this region the contribution of the
induced radiation to the photon fragmentation function exceeds the ordinary
vacuum radiation. Contrary to previous analyses our results show that at RHIC
and LHC energies the final-state interaction effects in quark-gluon plasma do
not suppress the direct photon production, and even may enhance it at p_{T}
about 5-15 GeV.Comment: 11 pages, 4 figure
Radiative parton energy loss and jet quenching in high-energy heavy-ion collisions
We study within the light-cone path integral approach [3] the effect of the
induced gluon radiation on high-p_{T} hadrons in high-energy heavy-ion
collisions. The induced gluon spectrum is represented in a new form which is
convenient for numerical simulations. For the first time, computations are
performed with a realistic parametrization of the dipole cross section. The
results are in reasonable agreement with suppression of high-p_{T} hadrons in
Au+Au collisions at \sqrt{s}=200 GeV observed at RHIC.Comment: 12 pages, 3 epsi figures. Typos correcte
Fully quantum treatment of the Landau--Pomeranchuk--Migdal effect in QED and QCD
For the first time a rigorous quantum treatment of the
Landau-Pomeranchuk-Migdal effect in QED and QCD is given. The rate of photon
(gluon) radiation by an electron (quark) in medium is expressed through the
Green's function of a two-dimensional Schr\"odinger equation with an imaginary
potential. In QED this potential is proportional to the dipole cross section
for scattering of pair off an atom, in QCD it is proportional to
the cross section of interaction with color centre of the color singlet
quark-antiquark-gluon system.Comment: E-mail: [email protected], [email protected]
Direct calculation of the triple-pomeron coupling for diffractive DIS and real photoproduction
We present a unified direct calculation of the triple-pomeron coupling
A_{3\Pom}(Q^{2}) for diffractive real photoproduction () and deep
inelastic scattering at large in the framework of the dipole approach
to the generalized BFKL pomeron. The small phenomenological value of
A_{3\Pom}(0)\approx 0.16\,GeV, which was a mystery, is related to the
small correlation radius \,fm for the perturbative gluons. We
confirm the early expectations of weak dependence of the dimensionfull
coupling A_{3\Pom}(Q^{2}) and predict that it rises by the factor
from real photoproduction to deep inelastic scattering.Comment: 14 pages, 1 figure (request from [email protected]),
Juelich preprint KFA-IKP(Th)-1994-3
Parton energy loss in an expanding quark-gluon plasma: Radiative vs collisional
We perform a comparison of the radiative and collisional parton energy losses
in an expanding quark-gluon plasma. The radiative energy loss is calculated
within the light-cone path integral approach. The collisional energy loss is
calculated using the Bjorken method with an accurate treatment of the binary
collision kinematics. Our numerical results demonstrate that for RHIC and LHC
conditions the collisional energy loss is relatively small in comparison to the
radiative one. We find an enhancement of the heavy quark radiative energy loss
as compared to that of the light quarks at high energies.Comment: 13 pages, 3 figure
Charged Current Diffractive Structure Functions
We present our study of the diffraction in charged current DIS. We analyse
the perturbatively tractable excitation of heavy quarks, emphasizing the
peculiarities of the Regge factorization breaking in excitation of open charm.Comment: Proceeding of LISHEP98 workshop on diffractive physic
Jet quenching with running coupling including radiative and collisional energy losses
We calculate the nuclear modification factor for RHIC and LHC conditions
accounting for the radiative and collisional parton energy loss with the
running coupling constant.We find that the RHIC data can be explained both in
the scenario with the chemically equilibrium quark-gluon plasma and purely
gluonic plasma with slightly different thermal suppression of the coupling
constant. The role of the parton energy gain due to gluon absorption is also
investigated. Our results show that the energy gain gives negligible effect.Comment: 11 pages, 3 figure
- …