724 research outputs found
Sequential charmonium dissociation
Finite temperature lattice QCD indicates that the charmonium ground state
J/psi can survive in a quark-gluon plasma up to 1.5 T_c or more, while the
excited states chi_c and psi-prime are dissociated just above T_c. We assume
that the chi_c suffers the same form of suppression as that observed for the
psi-prime in SPS experiments, and that the directly produced J/psi is
unaffected at presently available energy densities. This provides a
parameter-free description of J/psi and psi-prime suppression which agrees
quite well with that observed in SPS and RHIC data.Comment: 10 pages, 8 figure
Thermal Hadronization and Hawking-Unruh Radiation in QCD
We conjecture that because of color confinement, the physical vacuum forms an
event horizon for quarks and gluons which can be crossed only by quantum
tunneling, i.e., through the QCD counterpart of Hawking radiation by black
holes. Since such radiation cannot transmit information to the outside, it must
be thermal, of a temperature determined by the chromodynamic force at the
confinement surface, and it must maintain color neutrality. We explore the
possibility that the resulting process provides a common mechanism for thermal
hadron production in high energy interactions, from annihilation to
heavy ion collisions.Comment: 29 pages, 14 figure
Low energy Quantum Gravity from the Effective Average Action
Within the effective average action approach to quantum gravity, we recover
the low energy effective action as derived in the effective field theory
framework, by studying the flow of possibly non-local form factors that appear
in the curvature expansion of the effective average action. We restrict to the
one-loop flow where progress can be made with the aid of the non-local heat
kernel expansion. We discuss the possible physical implications of the scale
dependent low energy effective action through the analysis of the quantum
corrections to the Newtonian potential.Comment: 24 pages, 1 figure; minor corrections, references adde
A Quantitative Analysis of Charmonium Suppression in Nuclear Collisions
Data from J/psi and psi' production in p-A collisions are used to determine
the cross section for absorption of pre-resonance charmonium in nuclear matter.
The J/psi suppression in O-Cu, O-U and S-U collisions is fully reproduced by
the corresponding nuclear absorption, while Pb-Pb collisions show an additional
suppression increasing with centrality. We study the onset of this change in
terms of hadronic comover interactions and conclude that so far no conventional
hadronic description can consistently account for all data. Deconfinement,
starting at a critical point determined by central S-U collisions, is in accord
with the observed suppression pattern.Comment: 37 pages, 12 figures, uses epsfig style, LaTe
An evaluation of the second grader's knowledge and understanding of the property rights concept
Thesis (Ed.M.)--Boston UniversityThe general aim of this thesis was to test the extent to which the children had learned the property rights concept, and not the extent to which they had been able to integrate their knowledge of these rights with their actual behavior. More specifically it was the purpose of this study to discover (1) whether there was any differentiation between a second grader's understanding of property that was brand new and if property that had been used for a long time, (2) whether a child in the second grade differentiated in his understanding of property which was considered valuable and property which was not considered valuable, (3) whether children in the study differentiated in their understanding of property of different types, (4) whether there was any correlation between knowledge of property rights that second grade children had and nursery school training, number of siblings, status of siblings, Sunday School training, sex, age, and socio-economic status
Colour Deconfinement and Quarkonium Dissociation
We survey how quarkonia can be used to probe colour deconfinement in
relativistic nuclear collisions.Comment: plain TeX, 42 pages + 22 figures (not included); hard copies
available upon request. Review article to appear in "Quark Gluon Plasma ||",
R.C. Hwa (Editor), World Scientific, Singapor
Anomalous J/Psi suppression and the nature of deconfinement
We study the characteristic features of J/Psi suppression by deconfinement. A
first order phase transition leads to an essentially discontinuous onset of
anomalous J/Psi suppression. The different energy densities required for the
dissociation of different charmonium states result in a two-step suppression
pattern, in which first the J/Psi's from chi decays are suppressed and
subsequently the directly produced J/Psi states. Combining both features leads
to a unique form of J/Psi suppression in a deconfining medium.Comment: LaTex, 7 pages, 2 figure
On the Deconfinement Phase Transition in the Resonance Gas
We obtain the constraints on the ruling parameters of the dense hadronic gas
model at the critical temperature and propose the quasiuniversal ratios of the
thermodynamic quantities. The possible appearence of thermodynamical
instability in such a model is discussed.Comment: 7 pages, plain LaTeX, BI-TP 94/4
Transition rate of the Unruh-DeWitt detector in curved spacetime
We examine the Unruh-DeWitt particle detector coupled to a scalar field in an
arbitrary Hadamard state in four-dimensional curved spacetime. Using smooth
switching functions to turn on and off the interaction, we obtain a
regulator-free integral formula for the total excitation probability, and we
show that an instantaneous transition rate can be recovered in a suitable
limit. Previous results in Minkowski space are recovered as a special case. As
applications, we consider an inertial detector in the Rindler vacuum and a
detector at rest in a static Newtonian gravitational field. Gravitational
corrections to decay rates in atomic physics laboratory experiments on the
surface of the Earth are estimated to be suppressed by 42 orders of magnitude.Comment: 27 pages, 1 figure. v3: Typos corrected. Published versio
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