15 research outputs found
Dynamical Formation of Disoriented Chiral Condensates
We study the dynamical formation of disoriented chiral condensates in very
high energy nucleus-nucleus collisions using Bjorken hydrodynamics and
relativistic nucleation theory. It is the dynamics of the first order
confinement phase transition which controls the evolution of the system. Every
bubble or fluctuation of the new, hadronic, phase obtains its own chiral
condensate with a probability determined by the Boltzmann weight of the finite
temperature effective potential of the linear sigma model. We evaluate domain
size and chiral angle distributions, which can be used as initial conditions
for the solution of semiclassical field equations.Comment: 17 pages, latex and 10 ps figures available at
http://www.nbi.dk/~vischer/dcc.htm
Properties of exotic matter for heavy ion searches
We examine the properties of both forms of strange matter, small lumps of strange quark matter (strangelets) and of strange hadronic matter (Metastable Exotic Multihypernuclear Objects: MEMOs) and their relevance for present and future heavy ion searches. The strong and weak decays are discussed separately to distinguish between long-lived and short-lived candidates where the former ones are detectable in present heavy ion experiments while the latter ones in future heavy ion experiments, respectively. We find some long-lived strangelet candidates which are highly negatively charged with a mass to charge ratio like a anti deuteron (M/Z 2) but masses of A=10 to 16. We predict also many short-lived candidates, both in quark and in hadronic form, which can be highly charged. Purely hyperonic nuclei like the (2 02 ) are bound and have a negative charge while carrying a positive baryon number. We demonstrate also that multiply charmed exotics (charmlets) might be bound and can be produced at future heavy ion colliders
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Relativistic field-theoretical transport in condensed matter
We discuss a relativistic transport theory of condensed matter based on a
microscopic system containing bosonic and fermionic degrees of freedom interacting via 3 -
and 4-point interactions. We use the Dyson hierarchy as a solution to the underlying field
theory and truncate this hierarchy by parametrizing the 2-particle-irreducible kernels of the
4- and 5-point vertex functions. We then perform a complete crossing-symmetric reduction
of the 2-particle intermediate states of the theory. We obtain a reduction hierarchy and
show how to explore the quality of our truncation scheme using this reduction hierarchy.
Finally we discuss the problem of regularization of the theory in the case of hadronic matter
by either putting form factors directly in the action or by using dispersion relations to
introduce causal form factors into singular diagrams
Many--Particle Correlations in Relativistic Nuclear Collisions
Many--particle correlations due to Bose-Einstein interference are studied in
ultrarelativistic heavy--ion collisions. We calculate the higher order
correlation functions from the 2--particle correlation function by assuming
that the source is emitting particles incoherently. In particular
parametrizations of and relations between longitudinal, sidewards, outwards and
invariant radii and corresponding momenta are discussed. The results are
especially useful in low statistics measurements of higher order correlation
functions. We evaluate the three--pion correlation function recently measured
by NA44 and predict the 2--pion--2--kaon correlation function. Finally, many
particle Coulomb corrections are discussed.Comment: 5 corrected misprints, 14 pages, revtex, epsfig, 6 figures included,
manuscript also available at http://www.nbi.dk/~vischer/publications.htm
Inhomogeneous Nucleation of Quark-Gluon Plasma in High Energy Nuclear Collisions
We estimate the probability that a hard nucleon-nucleon collision is able to
nucleate a seed of quark--gluon plasma in the surrounding hot and dense
hadronic matter formed during a central collision of two large nuclei at AGS
energies. The probability of producing at least one such seed is on the order
of 1-100\%. We investigate the influence of quark--gluon plasma formation on
the observed multiplicity distribution and find that it may lead to noticable
structure in the form of a bump or shoulder.Comment: 16 pages, latex and 12 ps figures available on reques
Nucleation of Quark--Gluon Plasma from Hadronic Matter
The energy densities achieved during central collisions of large nuclei at
Brookhaven's AGS may be high enough to allow the formation of quark--gluon
plasma. Calculations based on relativistic nucleation theory suggest that rare
events, perhaps one in every 10 or 10, undergo the phase transition.
Experimental ramifications may include an enhancement in the ratio of pions to
baryons, a reduction in the ratio of deuterons to protons, and a larger source
size as seen by hadron interferometry.Comment: 22 pages, 7 figures available upon request, NUC--MINN--94/5--
Scattering in the Presence of Electroweak Phase Transition Bubble Walls
We investigate the motion of fermions in the presence of an electro\-weak
phase transition bubble wall. We derive and solve the Dirac equation for such
fer\-mions, and compute the transmission and reflection coefficients for
fermions traveling from the symmetric to the asymmetric phases separated by the
domain wall.Comment: TPI--MINN--54, NUC--MINN--93/30--T, UMN--TH--1226/93, LaTex, 29 page
Dynamics of Two Higgs Doublet CP Violation and Baryogenesis at the Electroweak Phase Transition
We quantitatively study the charge transport mechanism of electroweak
baryogenesis in a realistic two-Higgs-doublet model, comparing the
contributions from quarks and leptons reflecting from electroweak domain walls,
and comparing the exact profile of the CP-violating phase with a commonly used
ansatz. We note that the phenomenon of spontaneous CP violation at high
temperature can occur in this model, even when there is no CP violation at zero
temperature. We include all known effects which are likely to influence the
baryon production rate, including strong sphalerons, the nontrivial dispersion
relations of the quasiparticles in the plasma, and Debye screening of gauged
charges. We confirm the claim of Joyce, Prokopec and Turok that the reflection
of tau leptons from the wall gives the dominant effect. We conclude that this
mechanism is marginally strong enough to produce the observed baryon asymmetry
of the universe.Comment: 49 pp. latex, 6 figures; section on diffusion expanded and corrected,
published versio