16,509 research outputs found
Coulomb Glasses: A Comparison Between Mean Field and Monte Carlo Results
Recently a local mean field theory for both eqilibrium and transport
properties of the Coulomb glass was proposed [A. Amir et al., Phys. Rev. B 77,
165207 (2008); 80, 245214 (2009)]. We compare the predictions of this theory to
the results of dynamic Monte Carlo simulations. In a thermal equilibrium state
we compare the density of states and the occupation probabilities. We also
study the transition rates between different states and find that the mean
field rates underestimate a certain class of important transitions. We propose
modified rates to be used in the mean field approach which take into account
correlations at the minimal level in the sense that transitions are only to
take place from an occupied to an empty site. We show that this modification
accounts for most of the difference between the mean field and Monte Carlo
rates. The linear response conductance is shown to exhibit the Efros-Shklovskii
behaviour in both the mean field and Monte Carlo approaches, but the mean field
method strongly underestimates the current at low temperatures. When using the
modified rates better agreement is achieved
A CGC/saturation approach for angular correlations in proton-proton scattering
We generalized our model for the description of hard processes, and calculate
the value of the azimuthal angle correlations ( Fourier harmonics ), for
proton-proton scattering.The energy and multiplicity independence, as well as
the value of , turn out the be in accord with the experimental data, or
slightly larger.
Therefore, before making extreme assumptions on proton-proton collisions,
such as the production of quark-gluon plasma in the large multiplicity events,
we need to explain how these effect theBose-Einstein correlations which are so
large, that have to be taken into account, and which are able to describe the
angular correlations in proton-proton collisions, without including final state
interactionsComment: 26 pp. 17 figures in eps file
CGC/saturation approach: soft interaction at the LHC energies
In this paper we demonstrate that our model which is based on the
CGC/saturation approach, is able to describe the soft interaction collisions
including the new TOTEM prelimenary data at 13 TeV. We believe that this
strengthens the argument that the CGC/saturation approach is the only viable
candidate for an effective theory for high energy QCD.Comment: 6pp,4 figures. arXiv admin note: substantial text overlap with
arXiv:1706.07617, arXiv:1607.0059
Production of q bar-q Pairs in Proton-Nucleus Collisions at High Energies
We calculate production of quark-antiquark pairs in high energy
proton-nucleus collisions both in the quasi-classical approximation of
McLerran-Venugopalan model and including quantum small- evolution. The
resulting production cross section is explicitly expressed in terms of
Glauber-Mueller multiple rescatterings in the classical case and in terms of
dipole-nucleus scattering amplitude in the quantum evolution case. We
generalize the result of one of us (K.T.) beyond the aligned jet
configurations. We expand on the earlier results of Blaizot, Gelis and
Venugopalan by deriving quark production cross section including quantum
evolution corrections in rapidity intervals both between the quarks and the
target and between the quarks and the projectile.Comment: 18 pages, 3 figures; typos corrected, discussion extende
Properties of inclusive hadron production in Deep Inelastic Scattering on heavy nuclei at low x
In this paper we present a comprehensive study of inclusive hadron production
in DIS at low . Properties of the hadron spectrum are different in different
kinematic regions formed by three relevant momentum scales: photon virtuality
, hadron transverse momentum and the saturation momentum .
We investigate each kinematic region and derive the corresponding asymptotic
formulas for the cross section at the leading logarithmic order. We also
analyze the next-leading-order (NLO) corrections to the BFKL kernel that are
responsible for the momentum conservation. In particular, we establish the
asymptotic behavior of the forward elastic dipole--nucleus scattering amplitude
at high energies deeply in the saturation regime and a modification of the
pomeron intercept. We study the nuclear effect on the inclusive cross section
using the nuclear modification factor and its logarithmic derivative. We argue
that the later is proportional to the difference between the anomalous
dimension of the gluon distribution in nucleus and in proton and thus is a
direct measure of the coherence effects. To augment our arguments and present
quantitative results we performed numerical calculations in the kinematic
region that may be accessible by the future DIS experiments.Comment: 29 pages, 8 figure
Coulomb gap in the one-particle density of states in three-dimensional systems with localized electrons
The one-particle density of states (1P-DOS) in a system with localized
electron states vanishes at the Fermi level due to the Coulomb interaction
between electrons. Derivation of the Coulomb gap uses stability criteria of the
ground state. The simplest criterion is based on the excitonic interaction of
an electron and a hole and leads to a quadratic 1P-DOS in the three-dimensional
(3D) case. In 3D, higher stability criteria, including two or more electrons,
were predicted to exponentially deplete the 1P-DOS at energies close enough to
the Fermi level. In this paper we show that there is a range of intermediate
energies where this depletion is strongly compensated by the excitonic
interaction between single-particle excitations, so that the crossover from
quadratic to exponential behavior of the 1P-DOS is retarded. This is one of the
reasons why such exponential depletion was never seen in computer simulations.Comment: 6 pages, 1 figur
Hadron multiplicity in pp and AA collisions at LHC from the Color Glass Condensate
We provide quantitative predictions for the rapidity, centrality and energy
dependencies of inclusive charged-hadron productions for the forthcoming LHC
measurements in nucleus-nucleus collisions based on the idea of gluon
saturation in the color-glass condensate framework. Our formulation gives very
good descriptions of the first data from the LHC for the inclusive
charged-hadron production in proton-proton collisions, the deep inelastic
scattering at HERA at small Bjorken-x, and the hadron multiplicities in
nucleus-nucleus collisions at RHIC.Comment: 7 pages, 8 figures; v3: minor changes, one reference added, results
unchanged, the version to appear in Phys. Rev.
Measuring the saturation scale in nuclei
The saturation momentum seeing in the nuclear infinite momentum frame is
directly related to transverse momentum broadening of partons propagating
through the medium in the nuclear rest frame. Calculation of broadening within
the color dipole approach including the effects of saturation in the nucleus,
gives rise to an equation which describes well data on broadening in Drell-Yan
reaction and heavy quarkonium production.Comment: 11 pages, 5 figures, based on the talk presented by B.K. at the INT
workshop "Physics at a High Energy Electron Ion Collider", Seattle, October
200
Study of non-collinear parton dynamics in the prompt photon photoproduction at HERA
We investigate the prompt photon photoproduction at HERA within the framework
of kt-factorization QCD approach. Our consideration is based on the off-shell
matrix elements for the underlying partonic subprocesses. The unintegrated
parton densities in a proton and in a photon are determined using the
Kimber-Martin-Ryskin (KMR) prescription. Additionally, we use the CCFM-evolved
unintegrated gluon as well as valence and sea quark distributions in a proton.
A conservative error analisys is performed. Both inclusive and associated with
the hadronic jet production rates are investigated. The theoretical results are
compared with the recent experimental data taken by the H1 and ZEUS
collaborations. We study also the specific kinematical properties of the
photon-jet system which are strongly sensitive to the transverse momentum of
incoming partons. Using the KMR scheme, the contribution from the quarks
emerging from the earlier steps of the parton evolution is estimated and found
to be of 15 - 20 approximately.Comment: 22 pages, 13 figures, 2 tabl
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