5,558 research outputs found
AdS/CFT and the Information Paradox
The information paradox in the quantum evolution of black holes is studied
within the framework of the AdS/CFT correspondence. The unitarity of the CFT
strongly suggests that all information about an initial state that forms a
black hole is returned in the Hawking radiation. The CFT dynamics implies an
information retention time of order the black hole lifetime. This fact
determines many qualitative properties of the non-local effects that must show
up in a semi-classical effective theory in the bulk. We argue that no
violations of causality are apparent to local observers, but the semi-classical
theory in the bulk duplicates degrees of freedom inside and outside the event
horizon. Non-local quantum effects are required to eliminate this redundancy.
This leads to a breakdown of the usual classical-quantum correspondence
principle in Lorentzian black hole spacetimes.Comment: 16 pages, harvmac, reference added, minor correction
Dispersion Coefficients by a Field-Theoretic Renormalization of Fluid Mechanics
We consider subtle correlations in the scattering of fluid by randomly placed
obstacles, which have been suggested to lead to a diverging dispersion
coefficient at long times for high Peclet numbers, in contrast to finite
mean-field predictions. We develop a new master equation description of the
fluid mechanics that incorporates the physically relevant fluctuations, and we
treat those fluctuations by a renormalization group procedure. We find a finite
dispersion coefficient at low volume fraction of disorder and high Peclet
numbers.Comment: 4 pages, 1 figure; to appear in Phys. Rev. Let
A new measurement of K+(e4) decay and the s-wave pi-pi-scattering length a00
A sample of 400000 events from the decay K+->pi+pi-e+nu(e)(K(e4)) has been
collected in experiment E865 at the Brookhaven AGS. The analysis of these data
yields new measurements of the K(e4) branching ratio
(4.11+-0.01+-0.11)*10**(-5)), the s-wave pi-pi scattering length
a00=0.228+-0.012+-0.003, and the form factors F, G, and H of the hadronic
current and their dependence on the invariant pi-pi mass
Stability, Causality, and Lorentz and CPT Violation
Stability and causality are investigated for quantum field theories
incorporating Lorentz and CPT violation. Explicit calculations in the quadratic
sector of a general renormalizable lagrangian for a massive fermion reveal that
no difficulty arises for low energies if the parameters controlling the
breaking are small, but for high energies either energy positivity or
microcausality is violated in some observer frame. However, this can be avoided
if the lagrangian is the sub-Planck limit of a nonlocal theory with spontaneous
Lorentz and CPT violation. Our analysis supports the stability and causality of
the Lorentz- and CPT-violating standard-model extension that would emerge at
low energies from spontaneous breaking in a realistic string theory.Comment: 20 pages, accepted for publication in Physical Review
First observation of the decay K+ -> e+ nu mu+ mu-
Experiment 865 at the Brookhaven AGS has observed the decay K^+ -> e^+ nu
mu^+ mu^-. The branching ratio extracted is (1.72 +/- 0.37(stat) +/- 0.17(syst)
+/- 0.19(model)) x 10^{-8} where the third term in the error results from the
use of a model to extrapolate into a kinematic region dominated by background.Comment: 4 pages, 6 figures, Revtex4. Correction to figure and minor text
change
New, high statistics measurement of the K+ -> pi0 e+ nu (Ke3) branching ratio
E865 at the Brookhaven National Laboratory AGS collected about 70,000 K+(e3)
events with the purpose of measuring the relative K+(e3) branching ratio. The
pi0 in all the decays was detected using the e+e- pair from pi0 -> e+e-gamma
decay and no photons were required. Using the Particle Data Group branching
ratios for the normalization decays we obtain
BR(K+(e3(gamma))=(5.13+/-0.02(stat)+/-0.09(sys)+/-0.04(norm))%, where
V_{us}$ element of the CKM matrix, and the matrix's
unitarity are discussed.Comment: 4 pages, 5 figures; final version accepted by PR
An Improved upper limit on the decay K^+ -> pi^+ mu^+ e^-
Based on results of a search for the lepton-family-number-violating decay
with data collected by experiment E865 at the
Alternating Gradient Synchrotron of Brookhaven National Laboratory, we place an
upper limit on the branching ratio at (90% C.L.).
Combining the results with earlier E865 data and those of a previous
experiment, E777, an upper limit on the branching ratio of (90% C.L.) is obtained.Comment: v2: 13 pages, submitted to the Phys. Rev. D v3: 13 pages, resubmitted
to Phys. Rev. D (corrections include: a more detailed overview of the
combined analysis of the available experimntal data
Statistical Origin of Black Hole Entropy in Matrix Theory
The statistical entropy of black holes in M-theory is considered. Assuming
Matrix theory is the discretized light-cone quantization of a theory with
eleven-dimensional Lorentz invariance, we map the counting problem onto the
original Gibbons-Hawking calculation of the thermodynamic entropy.Comment: 9 pages, harvmac, (v2 References added, typo fixed), (v3 Some
clarifying comments added.
Magneto-Transport in the Two-Dimensional Lorentz Gas
We consider the two-dimensional Lorentz gas with Poisson distributed hard
disk scatterers and a constant magnetic field perpendicular to the plane of
motion. The velocity autocorrelation is computed numerically over the full
range of densities and magnetic fields with particular attention to the
percolation threshold between hopping transport and pure edge currents. The
Ohmic and Hall conductance are compared with mode-coupling theory and a recent
generalized kinetic equation valid for low densities and small fields. We argue
that the long time tail as persists for non-zero magnetic field.Comment: 7 pages, 14 figures. Uses RevTeX and epsfig.sty. Submitted to
Physical Review
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