2,298 research outputs found
Thermal Duality and Hagedorn Transition from p-adic Strings
We develop the finite temperature theory of p-adic string models. We find
that the thermal properties of these non-local field theories can be
interpreted either as contributions of standard thermal modes with energies
proportional to the temperature, or inverse thermal modes with energies
proportional to the inverse of the temperature, leading to a "thermal duality"
at leading order (genus one) analogous to the well known T-duality of string
theory. The p-adic strings also recover the asymptotic limits (high and low
temperature) for arbitrary genus that purely stringy calculations have yielded.
We also discuss our findings surrounding the nature of the Hagedorn transition.Comment: 4 pages and 4 figure
Acoustics of tachyon Fermi gas
We consider a Fermi gas of free tachyons as a continuous medium and find
whether it satisfies the causality condition. There is no stable tachyon matter
with the particle density below critical value and the Fermi momentum
that depends on the tachyon mass . The pressure
and energy density cannot be arbitrary small, but the situation is
not forbidden. Existence of shock waves in tachyon gas is also discussed. At
low density the tachyon matter remains stable but no shock wave
do survive.Comment: 14 pages, 2 figures (color
High temperature limit in static backgrounds
We prove that the hard thermal loop contribution to static thermal amplitudes
can be obtained by setting all the external four-momenta to zero before
performing the Matsubara sums and loop integrals. At the one-loop order we do
an iterative procedure for all the 1PI one-loop diagrams and at the two-loop
order we consider the self-energy. Our approach is sufficiently general to the
extent that it includes theories with any kind of interaction vertices, such as
gravity in the weak field approximation, for space-time dimensions. This
result is valid whenever the external fields are all bosonic.Comment: 15 pages, 11 figures. To be published in Physical Review
Neutrino Superfluidity
It is shown that Dirac-type neutrinos display BCS superfluidity for any
nonzero mass. The Cooper pairs are formed by attractive scalar Higgs boson
exchange between left- and right-handed neutrinos; in the standard SU(2)xU(1)
theory, right-handed neutrinos do not couple to any other boson. The value of
the gap, the critical temperature, and the Pippard coherence length are
calculated for arbitrary values of the neutrino mass and chemical potential.
Although such a superfluid could conceivably exist, detecting it would be a
major challenge.Comment: This is the version published in PR
On the imaginary parts and infrared divergences of two-loop vector boson self-energies in thermal QCD
We calculate the imaginary part of the retarded two-loop self-energy of a
static vector boson in a plasma of quarks and gluons of temperature T, using
the imaginary time formalism. We recombine various cuts of the self-energy to
generate physical processes. We demonstrate how cuts containing loops may be
reinterpreted in terms of interference between Order tree diagrams and
the Born term along with spectators from the medium. We apply our results to
the rate of dilepton production in the limit of dilepton invariant mass E>>T.
We find that all infrared and collinear singularities cancel in the final
result obtained in this limit.Comment: references added, typos corrected, slightly abridged, version
accepted for publication in Phys. Rev.
Open charm meson in nuclear matter at finite temperature beyond the zero range approximation
The properties of open charm mesons, , , and in
nuclear matter at finite temperature are studied within a self-consistent
coupled-channel approach. The interaction of the low lying pseudoscalar mesons
with the ground state baryons in the charm sector is derived from a -channel
vector-exchange model. The in-medium scattering amplitudes are obtained by
solving the Lippmann-Schwinger equation at finite temperature including Pauli
blocking effects, as well as , , and self-energies
taking their mutual influence into account. We find that the in-medium
properties of the meson are affected by the -meson self-energy through
the intermediate loops coupled to states. Similarly, dressing the
meson in the loops has an influence over the properties of
the meson.Comment: 23 pages, 9 figures, 2 table
SU(2) Chiral Sigma Model Study of Phase Transition in Hybrid Stars
We use a modified SU(2) chiral sigma model to study nuclear matter component
and simple bag model for quark matter constituting a neutron star. We also
study the phase transition of nuclear matter to quark matter with the mixed
phase characterized by two conserved charges in the interior of highly dense
neutron stars. Stable solutions of Tolman-Oppenheimer-Volkoff equations
representing hybrid stars are obtained with a maximum mass of 1.67
and radius around 8.9 km.Comment: 14 pages, 5 figure
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