6,229 research outputs found
The strange-quark chemical potential as an experimentally accessible "order parameter" of the deconfinement phase transition for finite baryon-density
We consider the change of the strange-quark chemical potential in the phase
diagram of nuclear matter, employing the Wilson loop and scalar quark
condensate order parameters, mass-scaled partition functions and enforcing
flavor conservation. Assuming the region beyond the hadronic phase to be
described by massive, correlated and interacting quarks, in the spirit of
lattice and effective QCD calculations, we find the strange-quark chemical
potential to change sign: from positive in the hadronic phase - to zero upon
deconfinement - to negative in the partonic domain. We propose this change in
the sign of the strange-quark chemical potential to be an experimentally
accessible order parameter and a unique, concise and well-defined indication of
the quark-deconfinement phase transition in nuclear matter.Comment: 22 pages, 14 figures within text, 2 figures(6,B3) as separate files.
To be published in J.Phys.G: Nucl.&Part.Phys. G28 (2002
On the push&pull protocol for rumour spreading
The asynchronous push&pull protocol, a randomized distributed algorithm for
spreading a rumour in a graph , works as follows. Independent Poisson clocks
of rate 1 are associated with the vertices of . Initially, one vertex of
knows the rumour. Whenever the clock of a vertex rings, it calls a random
neighbour : if knows the rumour and does not, then tells the
rumour (a push operation), and if does not know the rumour and knows
it, tells the rumour (a pull operation). The average spread time of
is the expected time it takes for all vertices to know the rumour, and the
guaranteed spread time of is the smallest time such that with
probability at least , after time all vertices know the rumour. The
synchronous variant of this protocol, in which each clock rings precisely at
times , has been studied extensively. We prove the following results
for any -vertex graph: In either version, the average spread time is at most
linear even if only the pull operation is used, and the guaranteed spread time
is within a logarithmic factor of the average spread time, so it is . In the asynchronous version, both the average and guaranteed spread times
are . We give examples of graphs illustrating that these bounds
are best possible up to constant factors. We also prove theoretical
relationships between the guaranteed spread times in the two versions. Firstly,
in all graphs the guaranteed spread time in the asynchronous version is within
an factor of that in the synchronous version, and this is tight.
Next, we find examples of graphs whose asynchronous spread times are
logarithmic, but the synchronous versions are polynomially large. Finally, we
show for any graph that the ratio of the synchronous spread time to the
asynchronous spread time is .Comment: 25 page
Systematics of thermodynamic quantities in a 3-region phase diagram from strange particle ratios
Model of Centauro and strangelet production in heavy ion collisions
We discuss the phenomenological model of Centauro event production in
relativistic nucleus-nucleus collisions. This model makes quantitative
predictions for kinematic observables, baryon number and mass of the Centauro
fireball and its decay products. Centauros decay mainly to nucleons, strange
hyperons and possibly strangelets. Simulations of Centauro events for the
CASTOR detector in Pb-Pb collisions at LHC energies are performed. The
signatures of these events are discussed in detail.Comment: 19 pages, LaTeX+revtex4, 14 eps-figures and 3 table
Light particle spectra from 35 MeV/nucleon 12C-induced reactions on 197Au
Energy spectra for p, d, t, 3He, 4He, and 6He from the reaction 12C+197Au at 35 MeV/nucleon are presented. A common intermediate rapidity source is identified using a moving source fit to the spectra that yields cross sections which are compared to analogous data at other bombarding energies and to several different models. The excitation function of the composite to proton ratios is compared with quantum statistical, hydrodynamic, and thermal models
Can Centauros or Chirons be the first observations of evaporating mini black holes?
We argue that the signals expected from the evaporation of mini black holes -
predicted in TeV-scale gravity models with large extra dimensions, and possibly
produced in ultra high energy collisions in the atmosphere - are quite similar
to the characteristics of the Centauro events, an old mystery of cosmic-ray
physics.Comment: 14 pages, LaTeX, one Table, uses rotate.sty and rotcapt.sty.
References added, typos corrected, footnotes moved into the tex
Single transverse-spin asymmetry in Drell-Yan lepton angular distribution
We calculate a single transverse-spin asymmetry for the Drell-Yan
lepton-pair's angular distribution in perturbative QCD. At leading order in the
strong coupling constant, the asymmetry is expressed in terms of a twist-3
quark-gluon correlation function T_F^{(V)}(x_1,x_2). In our calculation, the
same result was obtained in both light-cone and covariant gauge in QCD, while
keeping explicit electromagnetic current conservation for the virtual photon
that decays into the lepton pair. We also present a numerical estimate of the
asymmetry and compare the result to an existing other prediction.Comment: 15 pages, Revtex, 5 Postscript figures, uses aps.sty, epsfig.st
Formation of Centauro and Strangelets in Nucleus-Nucleus Collisions at the LHC and their Identification by the ALICE Experiment
We present a phenomenological model which describes the formation of a
Centauro fireball in nucleus-nucleus interactions in the upper atmosphere and
at the LHC, and its decay to non-strange baryons and Strangelets. We describe
the CASTOR detector for the ALICE experiment at the LHC. CASTOR will probe, in
an event-by-event mode, the very forward, baryon-rich phase space 5.6 < \eta <
7.2 in 5.5 A TeV central Pb + Pb collisions. We present results of simulations
for the response of the CASTOR calorimeter, and in particular to the traversal
of Strangelets.Comment: 4 pages, 4 figures, to appear in the proceedings of the 26th ICR
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