25 research outputs found
Four loop anomalous dimension of the second moment of the non-singlet twist-2 operator in QCD
We present the result of a calculation for the first even moment of the
non-singlet four-loop anomalous dimension of Wilson twist-2 operators in QCD
with full color and flavor structures.Comment: 8 pages, comparison with prediction from Pade approximation
(hep-ph/9905310) adde
A Gribov equation for the photon Green's function
We present a derivation of the Gribov equation for the gluon/photon Green's
function D(q). Our derivation is based on the second derivative of the
gauge-invariant quantity Tr ln D(q), which we interpret as the gauge-boson
`self-loop'. By considering the higher-order corrections to this quantity, we
are able to obtain a Gribov equation which sums the logarithmically enhanced
corrections. By solving this equation, we obtain the non-perturbative running
coupling in both QCD and QED. In the case of QCD, alpha_S has a singularity in
the space-like region corresponding to super-criticality, which is argued to be
resolved in Gribov's light-quark confinement scenario. For the QED coupling in
the UV limit, we obtain a \propto Q^2 behaviour for space-like Q^2=-q^2. This
implies the decoupling of the photon and an NJLVL-type effective theory in the
UV limit.Comment: 12 pages, 5 figures; version to be published in Eur. Phys. J.
The 16th moment of the three loop anomalous dimension of the non-singlet transversity operator in QCD
We present the result of the three loop anomalous dimension of non-singlet
transversity operator in QCD for the Mellin moment N=16. The obtained result
coincides with the prediction from arXiv:1203.1022 and can serve as a
confirmation of the correctness of the general expression for three loop
anomalous dimension of non-singlet transversity operator in QCD for the
arbitrary Mellin moment.Comment: 7 pages, 1 figure, minor changes in the tex
Транскрипционный анализ клеток линии HELA - продуцентов рекомбинантного пептидогликан-распознающего белка PGLYRP1 на разных стадиях развития инфекции Chlamydia trachomatis
Human peptidoglycan recognition proteins (PGLYRPs) are the components of innate immunity that exhibit antibacterial activity. In this study a cell line secreting recombinant PGLYRP1 into a culture medium was obtained. Transcriptional profiling of cell lines expressing PGLYRP1 was performed at different stages of C. trachomatis infection. Differential gene expression was studied using the whole transcriptome profiling method on the HumanHT-12 v4 Expression BeadChip microchip using the Illumina Direct Hybridization Whole-Gene Expression Assay protocol. Sample clustering followed by bioinformatics analysis revealed about 100 differentially expressed genes in response to infection with C. trachomatis. PGLYRP1- expressing cells infected with C. trachomatis had a similar transcriptional profile as non-infected cells.Пептидогликан-распознающие белки человека (PGLYRP) являются компонентами врожденного иммунитета, проявляющими антибактериальную активность. В данной работе получена клеточная линия, секретирующая рекомбинантный PGLYRP1 в культуральную среду. Проведено транскрипционное профилирование клеточных линий, синтезирующих PGLYRP1 после заражения C. trachomatis на разных стадиях развития инфекции. Методом полнотранскриптомного профилирования на микрочипе HumanHT-12 v4 Expression BeadChip по протоколу Illumina Direct Hybridization Whole-Gene Expression Assay изучена дифференциальная экспрессия генов. После кластеризации образцов и биоинформатического анализа обнаружено около 100 дифференциально экспрессирующихся генов в ответ на заражение C. trachomatis. Клетки, продуцирующие PGLYRP1 при заражении C. trachomatis, имели транскрипционный профиль, схожий с незараженными клетками
Three-loop renormalization of the N=1, N=2, N=4 supersymmetric Yang-Mills theories
We calculate the renormalization constants of the N=1, N=2, N=4
supersymmetric Yang-Mills theories in an arbitrary covariant gauge in the
dimensional reduction scheme up to three loops. We have found, that the
beta-functions for N=1 and N=4 SYM theories are the same from the different
triple vertices. This means that the dimensional reduction scheme works
correctly in these models up to third order of perturbative theory.Comment: 6 page
A model for the dependence of polarized structure functions
We present an update of a phenomenological model for the spin dependent
structure functions of the proton and neutron. This model is based
on a broken SU(6) wavefunction parametrized by the unpolarized structure
functions. The two free parameters of the model are choosen to fulfill the
Bjorken and Ellis--Jaffe sum rules. The model respects isospin symmetry and has
zero strange sea polarization. Using new values for from hyperon beta
decay the resulting dependent asymmetries are in perfect agreement
with the existing data. Therefore we do not see any evidence for a ``spin
crisis''. With two choices for the dependence of and
is predicted and shown to be small for both cases.Comment: 18 pages and 11 figures as uudecoded ps file
The Deuteron Spin-dependent Structure Function g1d and its First Moment
We present a measurement of the deuteron spin-dependent structure function
g1d based on the data collected by the COMPASS experiment at CERN during the
years 2002-2004. The data provide an accurate evaluation for Gamma_1^d, the
first moment of g1d(x), and for the matrix element of the singlet axial
current, a0. The results of QCD fits in the next to leading order (NLO) on all
g1 deep inelastic scattering data are also presented. They provide two
solutions with the gluon spin distribution function Delta G positive or
negative, which describe the data equally well. In both cases, at Q^2 = 3
(GeV/c)^2 the first moment of Delta G is found to be of the order of 0.2 - 0.3
in absolute value.Comment: fits redone using MRST2004 instead of MRSV1998 for G(x), correlation
matrix adde
The Spin-dependent Structure Function of the Proton g_1^p and a Test of the Bjorken Sum Rule
The inclusive double-spin asymmetry, A_1^p, has been measured at COMPASS in
deepinelastic polarised muon scattering off a large polarised NH3 target. The
data, collected in the year 2007, cover the range Q2 > 1 (GeV/c)^2, 0.004 < x <
0.7 and improve the statistical precision of g_1^p(x) by a factor of two in the
region x < 0.02. The new proton asymmetries are combined with those previously
published for the deuteron to extract the non-singlet spin-dependent structure
function g_1^NS(x,Q2). The isovector quark density, Delta_q_3(x,Q2), is
evaluated from a NLO QCD fit of g_1^NS. The first moment of Delta_q3 is in good
agreement with the value predicted by the Bjorken sum rule and corresponds to a
ratio of the axial and vector coupling constants g_A/g_V =
1.28+-0.07(stat)+-0.10(syst).Comment: 12 pages, 5 figure
The 2009 World Average of
Measurements of , the coupling strength of the Strong Interaction
between quarks and gluons, are summarised and an updated value of the world
average of is derived. Building up on previous reviews,
special emphasis is laid on the most recent determinations of . These
are obtained from -decays, from global fits of electroweak precision data
and from measurements of the proton structure function \F_2, which are based
on perturbative QCD calculations up to ; from hadronic event
shapes and jet production in \epem annihilation, based on
QCD; from jet production in deep inelastic scattering and from
decays, based on QCD; and from heavy quarkonia based on
unquenched QCD lattice calculations. Applying pragmatic methods to deal with
possibly underestimated errors and/or unknown correlations, the world average
value of results in . The
measured values of , covering energy scales from Q \equiv \mtau
= 1.78 GeV to 209 GeV, exactly follow the energy dependence predicted by QCD
and therefore significantly test the concept af Asymptotic Freedom.Comment: 14 pages, 7 figure