618 research outputs found
QFT, String Temperature and the String Phase of De Sitter Space-time
The density of mass levels \rho(m) and the critical temperature for strings
in de Sitter space-time are found. QFT and string theory in de Sitter space are
compared. A `Dual'-transform is introduced which relates classical to quantum
string lengths, and more generally, QFT and string domains. Interestingly, the
string temperature in De Sitter space turns out to be the Dual transform of the
QFT-Hawking-Gibbons temperature. The back reaction problem for strings in de
Sitter space is addressed selfconsistently in the framework of the `string
analogue' model (or thermodynamical approach), which is well suited to combine
QFT and string study.We find de Sitter space-time is a self-consistent solution
of the semiclassical Einstein equations in this framework. Two branches for the
scalar curvature R(\pm) show up: a classical, low curvature solution (-), and a
quantum high curvature solution (+), enterely sustained by the strings. There
is a maximal value for the curvature R_{\max} due to the string back reaction.
Interestingly, our Dual relation manifests itself in the back reaction
solutions: the (-) branch is a classical phase for the geometry with intrinsic
temperature given by the QFT-Hawking-Gibbons temperature.The (+) is a stringy
phase for the geometry with temperature given by the intrinsic string de Sitter
temperature. 2 + 1 dimensions are considered, but conclusions hold generically
in D dimensions.Comment: LaTex, 24 pages, no figure
CP Test in J/Psi -> gamma phi phi Decay
We propose to test CP symmetry in the decay \jp\to \gamma \phi\phi, for
which large data sample exists at BESII, and a data sample of
's will be collected with BESIII and CLEO-C program. We suggest some CP
asymmetries in this decay mode for CP test. Assuming that CP violation is
introduced by the electric- and chromo-dipole moment of charm quark, these CP
asymmetries can be predicted by using valence quark models. Our work shows a
possible way to get information about the electric- and chromo-dipole moment of
charm quark, which is little known. Our results show that with the current data
sample of , electric- and chromo-dipole moment can be probed at order
of . In the near future with a data sample, these
moments can be probed at order of .Comment: Misprints corrected. To appear in Phys. Lett.
Black Hole Entropy without Brick Walls
We present evidence which confirms a suggestion by Susskind and Uglum
regarding black hole entropy. Using a Pauli-Villars regulator, we find that 't
Hooft's approach to evaluating black hole entropy through a
statistical-mechanical counting of states for a scalar field propagating
outside the event horizon yields precisely the one-loop renormalization of the
standard Bekenstein-Hawking formula, S=\A/(4G). Our calculation also yields a
constant contribution to the black hole entropy, a contribution associated with
the one-loop renormalization of higher curvature terms in the gravitational
action.Comment: 15 pages, plain LaTex minor additions including some references;
version accepted for publicatio
Casimir energy in multiply connected static hyperbolic Universes
We generalize a previously obtained result, for the case of a few other
static hyperbolic universes with manifolds of nontrivial topology as spatial
sections.Comment: accepted for publicatio
Radiation reaction and energy-momentum conservation
We discuss subtle points of the momentum balance for radiating particles in
flat and curved space-time. An instantaneous balance is obscured by the
presence of the Schott term which is a finite part of the bound field momentum.
To establish the balance one has to take into account the initial and final
conditions for acceleration, or to apply averaging. In curved space-time an
additional contribution arises from the tidal deformation of the bound field.
This force is shown to be the finite remnant from the mass renormalization and
it is different both form the radiation recoil force and the Schott force. For
radiation of non-gravitational nature from point particles in curved space-time
the reaction force can be computed substituting the retarded field directly to
the equations of motion. Similar procedure is applicable to gravitational
radiation in vacuum space-time, but fails in the non-vacuum case. The existence
of the gravitational quasilocal reaction force in this general case seems
implausible, though it still exists in the non-relativistic approximation. We
also explain the putative antidamping effect for gravitational radiation under
non-geodesic motion and derive the non-relativistic gravitational quadrupole
Schott term. Radiation reaction in curved space of dimension other than four is
also discussedComment: Lecture given at the C.N.R.S. School "Mass and Motion in General
Relativity", Orleans, France, 200
Some general properties of the renormalized stress-energy tensor for static quantum states on (n+1)-dimensional spherically symmetric black holes
We study the renormalized stress-energy tensor (RSET) for static quantum
states on (n+1)-dimensional, static, spherically symmetric black holes. By
solving the conservation equations, we are able to write the stress-energy
tensor in terms of a single unknown function of the radial co-ordinate, plus
two arbitrary constants. Conditions for the stress-energy tensor to be regular
at event horizons (including the extremal and ``ultra-extremal'' cases) are
then derived using generalized Kruskal-like co-ordinates. These results should
be useful for future calculations of the RSET for static quantum states on
spherically symmetric black hole geometries in any number of space-time
dimensions.Comment: 9 pages, no figures, RevTeX4, references added, accepted for
publication in General Relativity and Gravitatio
Gauge Formulation for Higher Order Gravity
This work is an application of the second order gauge theory for the Lorentz
group, where a description of the gravitational interaction is obtained which
includes derivatives of the curvature. We analyze the form of the second field
strenght, , in terms of geometrical variables. All possible
independent Lagrangians constructed with quadratic contractions of and
quadratic contractions of are analyzed. The equations of motion for a
particular Lagrangian, which is analogous to Podolsky's term of his Generalized
Electrodynamics, are calculated. The static isotropic solution in the linear
approximation was found, exhibiting the regular Newtonian behaviour at short
distances as well as a meso-large distance modification.Comment: Published versio
Propagators and WKB-exactness in the plane wave limit of AdSxS
Green functions for the scalar, spinor and vector fields in a plane wave
geometry arising as a Penrose limit of are obtained. The
Schwinger-DeWitt technique directly gives the results in the plane wave
background, which turns out to be WKB-exact. Therefore the structural
similarity with flat space results is unveiled. In addition, based on the local
character of the Penrose limit, it is claimed that for getting the correct
propagators in the limit one can rely on the first terms of the direct geodesic
contribution in the Schwinger-DeWitt expansion of the original propagators .
This is explicitly shown for the Einstein Static Universe, which has the same
Penrose limit as with equal radii, and for a number of other
illustrative cases.Comment: 18 pages, late
Method to compute the stress-energy tensor for the massless spin 1/2 field in a general static spherically symmetric spacetime
A method for computing the stress-energy tensor for the quantized, massless,
spin 1/2 field in a general static spherically symmetric spacetime is
presented. The field can be in a zero temperature state or a non-zero
temperature thermal state. An expression for the full renormalized
stress-energy tensor is derived. It consists of a sum of two tensors both of
which are conserved. One tensor is written in terms of the modes of the
quantized field and has zero trace. In most cases it must be computed
numerically. The other tensor does not explicitly depend on the modes and has a
trace equal to the trace anomaly. It can be used as an analytic approximation
for the stress-energy tensor and is equivalent to other approximations that
have been made for the stress-energy tensor of the massless spin 1/2 field in
static spherically symmetric spacetimes.Comment: 34 pages, no figure
Cross-neutralization of cutaneous and mucosal Papillomavirus types with anti-sera to the amino terminus of L2
AbstractVaccination with papillomavirus L2 has been shown to induce neutralizing antibodies that protect against homologous type infection and cross-neutralize a limited number of genital HPVs. Surprisingly, we found that antibodies to bovine papillomavirus (BPV1) L2 amino acids 1–88 induced similar titers of neutralizing antibodies against Human papillomavirus (HPV)16 and 18 and BPV1 pseudoviruses and also neutralized HPV11 native virions. These antibodies also neutralized each of the other pseudovirus types tested, HPV31, HPV6 and Cottontail rabbit papillomavirus (CRPV) pseudoviruses, albeit with lower titers. HPV16, HPV18, HPV31, HPV6 and CRPV L2 anti-sera also displayed some cross-neutralization, but the titers were lower and did not encompass all pseudoviruses tested. This study demonstrates the presence of broadly cross-neutralizing epitopes at the N-terminus of L2 that are shared by cutaneous and mucosal types and by types that infect divergent species. BPV1 L2 was exceptionally effective at inducing cross-neutralizing antibodies to these shared epitopes
- …