942 research outputs found
NLO prescription for unintegrated parton distributions
We show how parton distributions unintegrated over the parton transverse
momentum, k_t, may be generated, at NLO accuracy, from the known integrated
(DGLAP-evolved) parton densities determined from global data analyses. A few
numerical examples are given, which demonstrate that sufficient accuracy is
obtained by keeping only the LO splitting functions together with the NLO
integrated parton densities. However, it is important to keep the precise
kinematics of the process, by taking the scale to be the virtuality rather than
the transverse momentum, in order to be consistent with the calculation of the
NLO splitting functions.Comment: 20 pages, 8 figures. v2: version to appear in Eur. Phys. J.
Noncolliding Squared Bessel Processes
We consider a particle system of the squared Bessel processes with index conditioned never to collide with each other, in which if
the origin is assumed to be reflecting. When the number of particles is finite,
we prove for any fixed initial configuration that this noncolliding diffusion
process is determinantal in the sense that any multitime correlation function
is given by a determinant with a continuous kernel called the correlation
kernel. When the number of particles is infinite, we give sufficient conditions
for initial configurations so that the system is well defined. There the
process with an infinite number of particles is determinantal and the
correlation kernel is expressed using an entire function represented by the
Weierstrass canonical product, whose zeros on the positive part of the real
axis are given by the particle-positions in the initial configuration. From the
class of infinite-particle initial configurations satisfying our conditions, we
report one example in detail, which is a fixed configuration such that every
point of the square of positive zero of the Bessel function is
occupied by one particle. The process starting from this initial configuration
shows a relaxation phenomenon converging to the stationary process, which is
determinantal with the extended Bessel kernel, in the long-term limit.Comment: v3: LaTeX2e, 26 pages, no figure, corrections made for publication in
J. Stat. Phy
The r-modes in accreting neutron stars with magneto-viscous boundary layers
We explore the dynamics of the r-modes in accreting neutron stars in two
ways. First, we explore how dissipation in the magneto-viscous boundary layer
(MVBL) at the crust-core interface governs the damping of r-mode perturbations
in the fluid interior. Two models are considered: one assuming an
ordinary-fluid interior, the other taking the core to consist of superfluid
neutrons, type II superconducting protons, and normal electrons. We show,
within our approximations, that no solution to the magnetohydrodynamic
equations exists in the superfluid model when both the neutron and proton
vortices are pinned. However, if just one species of vortex is pinned, we can
find solutions. When the neutron vortices are pinned and the proton vortices
are unpinned there is much more dissipation than in the ordinary-fluid model,
unless the pinning is weak. When the proton vortices are pinned and the neutron
vortices are unpinned the dissipation is comparable or slightly less than that
for the ordinary-fluid model, even when the pinning is strong. We also find in
the superfluid model that relatively weak radial magnetic fields ~ 10^9 G (10^8
K / T)^2 greatly affect the MVBL, though the effects of mutual friction tend to
counteract the magnetic effects. Second, we evolve our two models in time,
accounting for accretion, and explore how the magnetic field strength, the
r-mode saturation amplitude, and the accretion rate affect the cyclic evolution
of these stars. If the r-modes control the spin cycles of accreting neutron
stars we find that magnetic fields can affect the clustering of the spin
frequencies of low mass x-ray binaries (LMXBs) and the fraction of these that
are currently emitting gravitational waves.Comment: 19 pages, 8 eps figures, RevTeX; corrected minor typos and added a
referenc
Martensitic transition and magnetoresistance in a Cu-Al-Mn shape memory alloy. Influence of aging
We have studied the effect of ageing within the miscibility gap on the
electric, magnetic and thermodynamic properties of a non-stoichiometric Heusler
Cu-Al-Mn shape-memory alloy, which undergoes a martensitic transition from a
-based (-phase) towards a close-packed structure (-phase).
Negative magnetoresistance which shows an almost linear dependence on the
square of magnetization with different slopes in the - and -phases,
was observed. This magnetoresistive effect has been associated with the
existence of Mn-rich clusters with the CuAlMn-structure. The effect of an
applied magnetic field on the martensitic transition has also been studied. The
entropy change between the - and -phases shows negligible dependence
on the magnetic field but it decreases significantly with annealing time within
the miscibility gap. Such a decrease is due to the increasing amount of
CuMnAl-rich domains that do not transform martensitically.Comment: 9 pages, 9 figures, accepted for publication in PR
Antecedents and outcomes of consumer environmentally friendly attitudes and behaviour
With the intensification of problems relating to the environment, a growing number of consumers are becoming more ecologically conscious in their preferences and purchases of goods. This paper presents the results of a study conducted among 500 Cypriot consumers, focusing on the factors that shape consumer environmental attitudes and behaviour, as well as on the resulting outcomes. The findings confirmed that both the inward and outward environmental attitudes of a consumer are positively influenced by his/her degree of collectivism, long-term orientation, political involvement, deontology, and law obedience, but have no connection with liberalism. The adoption of an inward environmental attitude was also found to be conducive to green purchasing behaviour that ultimately leads to high product satisfaction. On the other hand, an outward environmental attitude facilitates the adoption of a general environmental behaviour, which is responsible for greater satisfaction with life. The findings of the study have important implications for shaping effective company offerings to consumers in target markets, as well as formulating appropriate policies at the governmental level to enhance environmental sensitivity among citizens
Determinantal process starting from an orthogonal symmetry is a Pfaffian process
When the number of particles is finite, the noncolliding Brownian motion
(BM) and the noncolliding squared Bessel process with index
(BESQ) are determinantal processes for arbitrary fixed initial
configurations. In the present paper we prove that, if initial configurations
are distributed with orthogonal symmetry, they are Pfaffian processes in the
sense that any multitime correlation functions are expressed by Pfaffians. The
skew-symmetric matrix-valued correlation kernels of the Pfaffians
processes are explicitly obtained by the equivalence between the noncolliding
BM and an appropriate dilatation of a time reversal of the temporally
inhomogeneous version of noncolliding BM with finite duration in which all
particles start from the origin, , and by the equivalence between
the noncolliding BESQ and that of the noncolliding squared
generalized meander starting from .Comment: v2: AMS-LaTeX, 17 pages, no figure, corrections made for publication
in J.Stat.Phy
Shockwaves and deep inelastic scattering within the gauge/gravity duality
Within the gauge/gravity correspondence, we discuss the general formulation
of the shockwave metric which is dual to a 'nucleus' described by the
strongly-coupled N=4 SYM theory in the limit where the number of colors Nc is
arbitrarily large. We emphasize that the 'nucleus' must possess Nc^2 degrees of
freedom per unit volume, so like a finite-temperature plasma, in order for a
supergravity description to exist. We critically reassess previous proposals
for introducing transverse inhomogeneity in the shockwave and formulate a new
proposal in that sense, which involves no external source but requires the
introduction of an 'infrared' cutoff which mimics confinement. This cutoff
however plays no role when the shockwave is probed by a highly virtual
projectile, so like in deep inelastic scattering. We consider two such
projectiles, the dilaton and the R-current, and compute the respective
structure functions including unitarity corrections. We find that there are no
leading-twist contributions to the structure functions at high virtuality,
meaning that there are no point-like constituents in the strongly coupled
'nucleus'. In the black-disk regime at low virtuality, the structure functions
are suggestive of parton saturation with occupation numbers of order one. The
saturation momentum Qs grows with the energy like Qs^2 ~ 1/x (with x the
Bjorken variable), which is the hallmark of graviton exchanges and is also
necessary for the fulfillment of the energy-momentum sum rules.Comment: 43 page
Efficacy and safety of daratumumab combined with all-trans retinoic acid in relapsed/refractory multiple myeloma
The efficacy of daratumumab depends partially on CD38 expression on multiple myeloma (MM) cells. We have previously shown that all-trans retinoic acid (ATRA) upregulates CD38 expression and reverts daratumumab-resistance ex vivo. We therefore evaluated the optimal dose, efficacy, and safety of daratumumab combined with ATRA in patients with daratumumab-refractory MM in a phase 1/2 study (NCT02751255). In part A of the study, 63 patients were treated with daratumumab monotherapy. Fifty patients with daratumumabrefractory MM were subsequently enrolled in part B and treated with daratumumab (reintensified schedule) combined with ATRA until disease progression. The recommended phase 2 dose of ATRA in combination with daratumumab was defined as 45 mg/m2. At this dose, the overall response rate (ORR) was 5%, indicating that the primary endpoint (ORR $15%) was not met. However, most patients (66%) achieved at least stable disease. After a median follow-up of 43 months, the median progression-free survival (PFS) for all patients was 2.8 months. Patients who previously achieved at least a partial response or minimal response/stable disease with prior daratumumab monotherapy had a significantly longer PFS compared with patients who immediately progressed during daratumumab as single agent (median PFS 3.4 and 2.8 vs 1.3 months). The median overall survival was 19.1 months. The addition of ATRA did not increase the incidence of adverse events. Flow cytometric analysis revealed that ATRA temporarily increased CD38 expression on immune cell subsets. In conclusion, the addition of ATRA and reintensification of daratumumab had limited activity in patients with daratumumab-refractory MM, which may be explained by the transient upregulation of CD38 expression. This trial was registered at www.clinicaltrials.gov as #NCT02751255
Non-Perturbative QCD Treatment of High-Energy Hadron-Hadron Scattering
Total cross-sections and logarithmic slopes of the elastic scattering
cross-sections for different hadronic processes are calculated in the framework
of the model of the stochastic vacuum. The relevant parameters of this model, a
correlation length and the gluon condensate, are determined from scattering
data, and found to be in very good agreement with values coming from completely
different sources of information. A parameter-free relation is given between
total cross-sections and slope parameters, which is shown to be remarkably
valid up to the highest energies for which data exist.Comment: 60 pages, Heidelberg preprin
Asymmetric Collision of Two Shock Waves in AdS_5
We consider high energy collisions of two shock waves in AdS_5 as a model of
ultrarelativistic nucleus-nucleus collisions in the boundary theory. We first
calculate the graviton field produced in the collisions in the NLO and NNLO
approximations, corresponding to three- and four-graviton exchanges with the
shock waves. We then consider the asymmetric limit where the energy density in
one shock wave is much higher than in the other one. In the boundary theory
this setup corresponds to proton-nucleus collisions, with the nucleus being the
denser of the two shock waves and the proton being the less dense one.
Employing the eikonal approximation we find the exact high energy analytic
solution for the metric in AdS_5 for the asymmetric collision of two
delta-function shock waves. The solution resums all-order graviton exchanges
with the "nucleus" shock wave and a single-graviton exchange with the "proton"
shock wave. Using the holographic renormalization prescription we read off the
energy-momentum tensor of the matter produced in proton-nucleus collisions. We
show in explicit detail that in the boundary theory the proton is completely
stopped by strong-coupling interactions with the nucleus, in agreement with our
earlier results. We also apply the eikonal technique to the asymmetric
collision of two unphysical delta-prime shock waves, which we introduced in an
earlier work as a means of modeling nuclear collisions with weak coupling
initial dynamics. We obtain a surprising result that, for delta-prime shock
waves, the multiple bulk graviton exchange series giving the leading
energy-dependent contribution to the energy-momentum tensor terminates at the
order of two graviton exchanges with the nucleus.Comment: 44 pages, 8 figures; v2: typos corrected, references added; v3: a
subsection added, more typos correcte
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