4,071 research outputs found
Partially Quenched Chiral Perturbation Theory to NNLO
This paper summarizes the recent calculations of the masses and decay
constants of the pseudoscalar mesons at the two-loop level, or NNLO, in
Partially Quenched Chiral Perturbation Theory (PQxPT). Possible applications
include chiral extrapolations of Lattice QCD, as well as the determination of
the low-energy constants (LEC:s) of QCD.Comment: To appear in the proceedings of PANIC 200
Partially Quenched and Three Flavour ChPT at Two Loops
A summary of recent progress in Chiral Perturbation Theory (ChPT) at the
two-loop level is given. A short introduction to ChPT is included, along with
an explanation of the usefulness of developing ChPT for partially quenched QCD.
Further, our recent work in partially quenched ChPT is reviewed, and a few
comments are given on older work in mesonic ChPT at the two-loop level. In
particular, we quote the present best values for the low-energy constants of
the chiral Lagrangian.Comment: 11 pages, invited talk at ``Final Euridice Meeting'', August 24-28
2006, Kazimierz, Polan
Transplanckian energy production and slow roll inflation
In this paper we investigate how the energy density due to a non-standard
choice of initial vacuum affects the expansion of the universe during
inflation. To do this we introduce source terms in the Friedmann equations
making sure that we respect the relation between gravity and thermodynamics. We
find that the energy production automatically implies a slow rolling
cosmological constant. Hence we also conclude that there is no well defined
value for the cosmological constant in the presence of sources. We speculate
that a non-standard vacuum can provide slow roll inflation on its own.Comment: 16 pages, 2 figures, version 2: minor corrections to section 4 and
references adde
The stringy nature of the 2d type-0A black hole
We investigate the thermodynamics of the RR charged two-dimensional type-0A
black hole background at finite temperature, and compare with known 0A matrix
model results. It has been claimed that there is a disagreement for the free
energy between the spacetime and the dual matrix model. Here we find that this
discrepancy is sensitive to how the cutoff is implemented on the spacetime
side. In particular, the disagreement is resolved once we put the cutoff at a
fixed distance away from the horizon, as opposed to a fixed position in space.
Furthermore, the mass and the entropy of the black hole itself add up to an
analytic contribution to the free energy, which is precisely reproduced by the
0A matrix model. We also use results from the 0A matrix model to predict the
next to leading order contribution to the entropy of the black hole. Finally,
we note that the black hole is characterized by a Hagedorn growth in its
density of states below the Hagedorn temperature. This, together with other
results, suggests there is a phase transition at this temperature.Comment: 1+21 pages; v2: Substantial changes in the body of the paper, main
results the same. Clarified discussion on the thermodynamics, added section
on a phase transition, references added. v3: Typos corrected. v4: Final
version, to appear in JHE
Microscopic Entropy of Non-dilatonic Branes: a 2D approach
We investigate non-dilatonic p-branes in the near-extremal, near-horizon
regime. A two-dimensional gravity model, obtained from dimensional reduction,
gives an effective description of the brane. We show that the AdS_p+2/CFT_p+1
correspondence at finite temperature admits an effective description in terms
of a AdS_2/CFT_1 duality endowed with a scalar field, which breaks the
conformal symmetry and generates a non-vanishing central charge. The entropy of
the CFT_1 is computed using Cardy formula. Fixing in a natural way a free,
dimensionless, parameter introduced in the model by a renormalization
procedure, we find exact agreement between the CFT_1 entropy and the
Bekenstein-Hawking entropy of the brane.Comment: 10 pages, no figure
Probing F-theory With Multiple Branes
We study multiple 3-branes on an F theory orientifold. The world-volume
theory of the 3-branes is d=4, N=2 Sp(2k) gauge theory with an antisymmetric
tensor and four flavors of matter in the fundamental. The solution of this
gauge theory is found for vanishing bare mass of the antisymmetric tensor
matter, and massive fundamental matter. The integrable system underlying this
theory is constructed.Comment: 9 pages, harvma
A not so brief commentary on cosmological entropy bounds
There has been, quite recently, a discussion on how holographic-inspired
bounds might be used to encompass the present-day dark energy and
early-universe inflation into a single paradigm. In the current treatment, we
point out an inconsistency in the proposed framework and then provide a viable
resolution. We also elaborate on some of the implications of this framework and
further motivate the proposed holographic connection. The manuscript ends with
a more speculative note on cosmic time as an emergent (holographically induced)
construct.Comment: 12 pages and Revtex; (v2) reference added and a few cosmetic change
Repetition of contaminating question types when children and youths with intellectual disabilities are interviewed
Background The present study examined the effects of repeating questions in interviews investigating the possible sexual abuse of children and youths who had a variety of intellectual disabilities. We predicted that the repetition of option-posing and suggestive questions would lead the suspected victims to change their responses, making it difficult to understand what actually happened. Inconsistency can be a key factor when assessing the reliability of witnesses. Materials Case files and transcripts of investigative interviews with 33 children and youths who had a variety of intellectual disabilities were obtained from prosecutors in Sweden. The interviews involved 25 females and 9 males whose chronological ages were between 5.4 and 23.7 years when interviewed (M = 13.2 years). Results Six per cent of the questions were repeated at least once. The repetition of focused questions raised doubts about the reports because the interviewees changed their answers 40% of the time. Conclusions Regardless of the witnesses' abilities, it is important to obtain reports that are as accurate and complete as possible in investigative interviews. Because this was a field study, we did not know which responses were accurate, but repetitions of potentially contaminating questions frequently led the interviewees to contradict their earlier answers. This means that the interviewers' behaviour diminished the usefulness of the witnesses' testimony
Three-Flavor Partially Quenched Chiral Perturbation Theory at NNLO for Meson Masses and Decay Constants
We discuss Partially Quenched Chiral Perturbation Theory (PQPT) and
possible fitting strategies to Lattice QCD data at next-to-next-to-leading
order (NNLO) in the mesonic sector. We also present a complete calculation of
the masses of the charged pseudoscalar mesons, in the supersymmetric
formulation of PQPT. Explicit analytical results are given for up to
three nondegenerate sea quark flavors, along with the previously unpublished
expression for the pseudoscalar meson decay constant for three nondegenerate
sea quark flavors. The numerical analysis in this paper demonstrates that the
corrections at NNLO are sizable, as expected from earlier work.Comment: 31 pages, numerical discussion extended including convergence NLO to
NNL
Space Noncommutativity Corrections to the Cardy-Verlinde Formula
In this letter we compute the corrections to the Cardy-Verlinde formula of
Schwarzschild black holes. These corrections stem from the space
noncommutativity. Because the Schwarzschild black holes are non rotating, to
the first order of perturbative calculations, there is no any effect on the
properties of black hole due to the noncommutativity of space.Comment: 7 pages, no figures, accepted for publication in Int. J. Mod. Phys.
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