1,018 research outputs found
Non-Abelian Energy Loss at Finite Opacity
A systematic expansion in opacity, , is used to clarify the
non-linear behavior of induced gluon radiation in quark-gluon plasmas. The
inclusive differential gluon distribution is calculated up to second order in
opacity and compared to the zeroth order (factorization) limit. The opacity
expansion makes it possible to take finite kinematic constraints into account
that suppress jet quenching in nuclear collisions below RHIC (
AGeV) energies.Comment: 4 pages (revtex) with 3 eps figures, submitted to PR
Collisional Energy Loss of Non Asymptotic Jets in a QGP
We calculate the collisional energy loss suffered by a heavy (charm) quark
created at a finite time within a Quark Gluon Plasma (QGP) in the classical
linear response formalism as in Peigne {\it et al.} \cite{peigne}. We pay close
attention to the problem of formulating a suitable current and the isolation of
binding and radiative energy loss effects. We find that unrealistic large
binding effects arising in previous formulations must be subtracted. The finite
time correction is shown to be important only for very short length scales on
the order of a Debye length. The overall energy loss is similar in magnitude to
the energy loss suffered by a charge created in the asymptotic past. This
result has significant implications for the relative contribution to energy
loss from collisional and radiative sources and has important ramifications for
the ``single electron puzzle'' at RHIC.Comment: 15 Pages, 11 figures, revte
Jet quenching in thin plasmas
We investigate the energy loss of quarks and gluons produced in hard
processes resulting from final state rescatterings in a finite quark-gluon
plasma. The angular distribution of the soft gluon bremsstrahlung induced by
n_s=1 rescatterings in the plasma is computed in the Gyulassy-Wang model.
Special focus is on how the interference between the initial hard radiation
amplitude, the multiple induced Gunion-Bertsch radiation amplitudes, and gluon
rescattering amplitudes modifies the classical parton cascade results.Comment: 4 pages in Latex and 3 EPS figures, Proceedings of the Quark
Matter'99 Conference, 10-15 May, 1999, Torin
Jet Tomography of Au+Au Reactions Including Multi-gluon Fluctuations
Jet tomography is the analysis of the attenuation pattern of high transverse
momentum hadrons to determine certain line integral transforms of the density
profile of the QCD matter produced in ultra-relativistic nuclear collisions. In
this letter, we calculate the distortion of jet tomography due to multi-gluon
fluctuations within the GLV radiative energy loss formalism. We find that
fluctuations of the average gluon number, ~ 3 for RHIC initial
conditions, reduce the attenuation of pions by approximately a factor Z ~
0.4-0.5. Therefore the plasma density inferred from jet tomography without
fluctuations must be enhanced by a factor 1/Z ~ 2.Comment: 6 pages, 4 .eps figures, uses REVTEX and bbox.st
Open Charm and Beauty at Ultrarelativistic Heavy Ion Colliders
Important goals of RHIC and LHC experiments with ion beams include the
creation and study of new forms of matter, such as the Quark Gluon Plasma.
Heavy quark production and attenuation will provide unique tomographic probes
of that matter. We predict the suppression pattern of open charm and beauty in
collisions at RHIC and LHC energies based on the DGLV formalism of
radiative energy loss. A cancelation between effects due to the
energy dependence of the high slope and heavy quark energy loss is
predicted to lead to surprising similarity of heavy quark suppression at RHIC
and LHC.Comment: 4 pages, 6 *.eps files combined into 4 figure
Anomalous Anti-proton to Negative Pion Ratio as Revealed by Jet Quenching at RHIC
We study the apparent discrepancy between the standard PQCD predictions for
the meson and baryon ratios and multiplicities at moderate high GeV
and recent experimental measurements in collisions at
GeV at the Relativistic Heavy Ion Collider (RHIC). We show
that the differences, most pronounced in central collisions, can be explained
by a strong non-perturbative baryon Junction component, which dominates the
currently accessible experimental window and the non-abelian energy
loss of fast partons propagating through hot and dense medium. The recently
introduced two component hybrid model, which combines a quenched jet PQCD
calculation in the Gyulassy-Levai-Vitev (GLV) formalism and a phenomenological
"soft" part, is further elaborated to take into account the full 3D expansion
in the pre-hadronization phase and include particle flavor dependent "soft"
inverse slopes as suggested by the baryon Junction picture. We show that such
approach can resolve what seems to be a factor of difference in the
moderate high suppression of and as recently reported by
the PHENIX collaboration. The observed quenching of the high particle
spectra and the large and ratios as a function of
are found to be consistent with a creation of a deconfined phase and
non-abelian energy loss of fast partons in a plasma of initial gluon rapidity
density .Comment: 5 pages, uses revtex and bbox.sty, INPC 2001 conference proceeding
Testing AdS/CFT Deviations from pQCD Heavy Quark Energy Loss with Pb+Pb at LHC
Heavy quark jet quenching in nuclear collisions at LHC is predicted and
compared using the classical gravity AdS/CFT correspondence and Standard Model
perturbative QCD. The momentum independence and inverse quark mass dependence
of the drag coefficient in AdS/CFT differs substantially from the
characteristic log(pT/M)/pT variation of the drag in QCD. We propose that the
measurement of the momentum dependence of the double ratio of the nuclear
modification factors of charm and bottom jets is a robust observable that can
be used to search for strong coupling deviations from perturbative QCD
predictions.Comment: 4 pages, 2 figure
3D Jet Tomography of Twisted Strongly Coupled Quark Gluon Plasmas
The triangular enhancement of the rapidity distribution of hadrons produced
in p+A reactions relative to p+p is a leading order in A^{1/3}/log(s) violation
of longitudinal boost invariance at high energies. In A+A reactions this leads
to a trapezoidal enhancement of the local rapidity density of produced gluons.
The local rapidity gradient is proportional to the local participant number
asymmetry, and leads to an effective rotation in the reaction plane. We propose
that three dimensional jet tomography, correlating the long range rapidity and
azimuthal dependences of the nuclear modification factor,
R_{AA}(\eta,\phi,p_\perp; b>0), can be used to look for this intrinsic
longitudinal boost violating structure of collisions to image the
produced twisted strongly coupled quark gluon plasma (sQGP). In addition to
dipole and elliptic azimuthal moments of R_{AA}, a significant high p_\perp
octupole moment is predicted away from midrapidity. The azimuthal angles of
maximal opacity and hence minima of R_{AA} are rotated away from the normal to
the reaction plane by an `Octupole Twist' angle, \theta_3(\eta), at forward
rapidities.Comment: 10 Pages, 16 Figures, RevTex, Replaced with Peer reviewed verion for
PR
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