5,747 research outputs found
Synchrotron radiation by fast fermions in heavy-ion collisions
We study the synchrotron radiation of gluons by fast quarks in strong
magnetic field produced by colliding relativistic heavy-ions. We argue that due
to high electric conductivity of plasma, time variation of the magnetic field
is slow and estimate its relaxation time. We calculate the energy loss due to
synchrotron radiation of gluons by fast quarks. We find that the typical energy
loss per unit length for a light quark at LHC is a few GeV per fm. This effect
alone predicts quenching of jets with up to about 20 GeV. We also show
that the spin-flip transition effect accompanying the synchrotron radiation
leads to a strong polarization of quarks and leptons with respect to the
direction of the magnetic field. Observation of the lepton polarization may
provide a direct evidence of existence of strong magnetic field in heavy-ion
collisions.Comment: 10 pages, 6 figures; v3: estimate of the relaxation time of magnetic
field is revised, acknowledgment adde
Pseudo-epsilon expansion and the two-dimensional Ising model
Starting from the five-loop renormalization-group expansions for the
two-dimensional Euclidean scalar \phi^4 field theory (field-theoretical version
of two-dimensional Ising model), pseudo-\epsilon expansions for the Wilson
fixed point coordinate g*, critical exponents, and the sextic effective
coupling constant g_6 are obtained. Pseudo-\epsilon expansions for g*, inverse
susceptibility exponent \gamma, and g_6 are found to possess a remarkable
property - higher-order terms in these expansions turn out to be so small that
accurate enough numerical estimates can be obtained using simple Pade
approximants, i. e. without addressing resummation procedures based upon the
Borel transformation.Comment: 4 pages, 4 tables, few misprints avoide
Six-loop expansion study of three-dimensional -vector model with cubic anisotropy
The six-loop expansions of the renormalization-group functions of
-vector model with cubic anisotropy are calculated within the minimal
subtraction (MS) scheme in dimensions. The
expansions for the cubic fixed point coordinates, critical exponents
corresponding to the cubic universality class and marginal order parameter
dimensionality separating different regimes of critical behavior are
presented. Since the expansions are divergent numerical estimates
of the quantities of interest are obtained employing proper resummation
techniques. The numbers found are compared with their counterparts obtained
earlier within various field-theoretical approaches and by lattice
calculations. In particular, our analysis of strengthens the existing
arguments in favor of stability of the cubic fixed point in the physical case
Measurement of the ionization yield of nuclear recoils in liquid argon at 80 and 233 keV
The energy calibration of nuclear recoil detectors is of primary importance
to rare-event experiments such as those of direct dark matter search and
coherent neutrino-nucleus scattering. In particular, such a calibration is
performed by measuring the ionization yield of nuclear recoils in liquid Ar and
Xe detection media, using neutron elastic scattering off nuclei. In the present
work, the ionization yield for nuclear recoils in liquid Ar has for the first
time been measured in the higher energy range, at 80 and 233 keV, using a
two-phase Cryogenic Avalanche Detector (CRAD) and DD neutron generator. The
ionization yield in liquid Ar at an electric field of 2.3 kV/cm amounted to
7.8+/-1.1 and 9.7+/-1.3 e-/keV at 80 and 233 keV respectively. The Jaffe model
for nuclear recoil-induced ionization, in contrast to that Thomas-Imel, can
probably consistently describe the energy dependence of the ionization yield.Comment: 6 pages, 6 figures. Fig. 6 changed. Submitted to EP
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