10,070 research outputs found
Generalized minimizers of convex integral functionals, Bregman distance, Pythagorean identities
Integral functionals based on convex normal integrands are minimized subject
to finitely many moment constraints. The integrands are finite on the positive
and infinite on the negative numbers, strictly convex but not necessarily
differentiable. The minimization is viewed as a primal problem and studied
together with a dual one in the framework of convex duality. The effective
domain of the value function is described by a conic core, a modification of
the earlier concept of convex core. Minimizers and generalized minimizers are
explicitly constructed from solutions of modified dual problems, not assuming
the primal constraint qualification. A generalized Pythagorean identity is
presented using Bregman distance and a correction term for lack of essential
smoothness in integrands. Results are applied to minimization of Bregman
distances. Existence of a generalized dual solution is established whenever the
dual value is finite, assuming the dual constraint qualification. Examples of
`irregular' situations are included, pointing to the limitations of generality
of certain key results
How much entropy is produced in strongly coupled Quark-Gluon Plasma (sQGP) by dissipative effects?
We argue that estimates of dissipative effects based on the first-order
hydrodynamics with shear viscosity are potentially misleading because higher
order terms in the gradient expansion of the dissipative part of the stress
tensor tend to reduce them. Using recently obtained sound dispersion relation
in thermal =4 supersymmetric plasma, we calculate the effect
of these high order terms for Bjorken expansion appropriate to RHIC/LHC
collisions. A reduction of entropy production is found to be substantial, up to
an order of magnitude.Comment: 4 pages, 4 figur
How well does NLO pQCD describe strangeness in collisions at = 200 GeV in STAR?
We present measurements of the transverse momentum spectra for
, , and their antiparticles in p+p
collisions at . The extracted mid-rapidity yields and
are in agreement with previous experiments while
they have smaller statistical errors. We compare the measured spectra for
and to the latest available calculations from
NLO pQCD and see good agreement for the above 1.5 GeV/c.Comment: conference proceedings, Strangeness in Quark Matter 2004, 5 pages,
submitted to Journal Physics G, final version submitted to journal incl.
modifications requested by edito
Recommended from our members
NPAS4 recruits CCK basket cell synapses and enhances cannabinoid-sensitive inhibition in the mouse hippocampus.
Experience-dependent expression of immediate-early gene transcription factors (IEG-TFs) can transiently change the transcriptome of active neurons and initiate persistent changes in cellular function. However, the impact of IEG-TFs on circuit connectivity and function is poorly understood. We investigate the specificity with which the IEG-TF NPAS4 governs experience-dependent changes in inhibitory synaptic input onto CA1 pyramidal neurons (PNs). We show that novel sensory experience selectively enhances somatic inhibition mediated by cholecystokinin-expressing basket cells (CCKBCs) in an NPAS4-dependent manner. NPAS4 specifically increases the number of synapses made onto PNs by individual CCKBCs without altering synaptic properties. Additionally, we find that sensory experience-driven NPAS4 expression enhances depolarization-induced suppression of inhibition (DSI), a short-term form of cannabinoid-mediated plasticity expressed at CCKBC synapses. Our results indicate that CCKBC inputs are a major target of the NPAS4-dependent transcriptional program in PNs and that NPAS4 is an important regulator of plasticity mediated by endogenous cannabinoids
Fluctuations from dissipation in a hot non-Abelian plasma
We consider a transport equation of the Boltzmann-Langevin type for
non-Abelian plasmas close to equilibrium to derive the spectral functions of
the underlying microscopic fluctuations from the entropy. The correlator of the
stochastic source is obtained from the dissipative processes in the plasma.
This approach, based on classical transport theory, exploits the well-known
link between a linearized collision integral, the entropy and the spectral
functions. Applied to the ultra-soft modes of a hot non-Abelian (classical or
quantum) plasma, the resulting spectral functions agree with earlier findings
obtained from the microscopic theory. As a by-product, it follows that
B\"odeker's effective theory is consistent with the fluctuation-dissipation
theorem.Comment: 9 pages, revtex, no figures, identical to published versio
Hadronic Entropy Enhancement and Low Density QGP
Recent studies show that for central collisions the rising of the incident
energy from AGS to RHIC decreases the value of the chemical potential in the
Hadron-QGP phase diagram. Thus, the formation of QGP at RHIC energies in
central collisions may be expected to occur at very small values of the
chemical potential. Using many different relativistic mean-field hadronic
models (RMF) at this regime we show that the critical temperature for the
Hadron-QGP transition is hadronic model independent. We have traced back the
reason for this and conclude that it comes from the fact that the QGP entropy
is much larger than the hadronic entropy obtained in all the RMF models. We
also find that almost all of these models present a strong entropy enhancement
in the hadronic sector coming from the baryonic phase transition to a
nucleon-antinucleon plasma. This result is in agreement with the recent data
obtained in the STAR collaboration at RHIC where it was found a rich
proton-antiproton matter
Evidence of early multi-strange hadron freeze-out in high energy nuclear collisions
Recently reported transverse momentum distributions of strange hadrons
produced in Pb(158AGeV) on Pb collisions and corresponding results from the
relativistic quantum molecular dynamics (RQMD) approach are examined. We argue
that the experimental observations favor a scenario in which multi-strange
hadrons are formed and decouple from the system rather early at large energy
densities (around 1 GeV/fm). The systematics of the strange and non-strange
particle spectra indicate that the observed transverse flow develops mainly in
the late hadronic stages of these reactions.Comment: 4 pages, 4 figure
- …