37 research outputs found
Homogeneous nucleation of quark-gluon plasma, finite size effects and long-lived metastable objects
The general formalism of homogeneous nucleation theory is applied to study
the hadronization pattern of the ultra-relativistic quark-gluon plasma (QGP)
undergoing a first order phase transition. A coalescence model is proposed to
describe the evolution dynamics of hadronic clusters produced in the nucleation
process. The size distribution of the nucleated clusters is important for the
description of the plasma conversion. The model is most sensitive to the
initial conditions of the QGP thermalization, time evolution of the energy
density, and the interfacial energy of the plasma-hadronic matter interface.
The rapidly expanding QGP is first supercooled by about . Then it reheats again up to the critical temperature T_c. Finally it
breaks up into hadronic clusters and small droplets of plasma. This fast
dynamics occurs within the first . The finite size effects and
fluctuations near the critical temperature are studied. It is shown that a drop
of longitudinally expanding QGP of the transverse radius below 4.5 fm can
display a long-lived metastability. However, both in the rapid and in the
delayed hadronization scenario, the bulk pion yield is emitted by sources as
large as 3-4.5 fm. This may be detected experimentally both by a HBT
interferometry signal and by the analysis of the rapidity distributions of
particles in narrow p_T-intervals at small p_T on an event-by-event basis.Comment: 29 pages, incl. 12 figures and 1 table; to be published in Phys. Rev.
Scientific Highlights of the HETE-2 Mission
The HETE-2 mission has been highly productive. It has observed more than 250
GRBs so far. It is currently localizing 25 - 30 GRBs per year, and has
localized 43 GRBs to date. Twenty-one of these localizations have led to the
detection of X-ray, optical, or radio afterglows, and as of now, 11 of the
bursts with afterglows have known redshifts. HETE-2 has confirmed the
connection between GRBs and Type Ic supernovae, a singular achievement and
certainly one of the scientific highlights of the mission so far. It has
provided evidence that the isotropic-equivalent energies and luminosities of
GRBs are correlated with redshift, implying that GRBs and their progenitors
evolve strongly with redshift. Both of these results have profound implications
for the nature of GRB progenitors and for the use of GRBs as a probe of
cosmology and the early universe. HETE-2 has placed severe constraints on any
X-ray or optical afterglow of a short GRB. It is also solving the mystery of
"optically dark' GRBs, and revealing the nature of X-ray flashes.Comment: 10 pages, 9 figures, to appear in proc. "The Restless High-Energy
Universe", Royal Tropical Institute, Amsterdam; revised text, added ref
The polarization evolution of the optical afterglow of GRB 030329
We report 31 polarimetric observations of the afterglow of GRB 030329 with
high signal-to-noise and high sampling frequency. The data imply that the
afterglow magnetic field has small coherence length and is mostly random,
probably generated by turbulence.Comment: 2003 GRB Conference, Santa Fe, Oct. 2003, 1 ps-figur
MEtop - a generator for single top production via FCNC interactions
We present a generator for single top quark production via flavour-changing
neutral currents. The MEtop event generator allows for Next-to-Leading-Order
direct top production and Leading-Order production of several other
single top processes. A few packages with definite sets of dimension six
operators are available. We discuss how to improve the bounds on the effective
operators and how well new physics can be probed with each set of independent
dimension six operators.Comment: 26 pages, 22 figure
Successful Treatment of Iron Overload by Phlebotomies in a Patient With Severe Congenital Dyserythropoietic Anemia Type II
Comparison of anthelmintic activity of pyrantel, praziquantel, and nitazoxanide against Anoplocephala perfoliata in Horses
The Social Time of Organizational Payment Systems
This article explores the relationships between time use and the social construction of meaning surrounding the operation of wage payment systems in three chemical industry organizations. It explores some of the ways that organizational time is subdivided and prioritized, and focuses on the way that patterns of payment for time contribute towards the formation of managerial and shop floor identities. These ideas are developed through the analysis of ethnographic research data, which supports the view that there are multiple kinds of social time in work organizations. It is suggested that much of the management literature concerned with the subject of payment systems treats time as finite, exhaustible and irreversible and this has implications for the way that payment systems are understood by practising managers. Managerial time codes reflect a closely scheduled time culture and reinforce a discourse of progress, whereas employees continue to see work time as something for which they should be compensated