119233640
Derivation of the blackfold effective theory
A bstractWe study fluctuations and deformations of black branes over length scales larger than the horizon radius. We prove that the Einstein equations for the perturbed p-brane yield, as constraints, the equations of the effective blackfold theory. We solve the Einstein equations for the perturbed geometry and show that it remains regular on and outside the black brane horizon. This study provides an ab initio derivation of the blackfold effective theory and gives explicit expressions for the metrics near the new black holes and black branes that result from it, to leading order in a derivative expansion.
118642962
Black brane viscosity and the Gregory-Laflamme instability
We study long wavelength perturbations of neutral black p-branes in asymptotically flat space and show that, as anticipated in the blackfold approach, solutions of the relativistic hydrodynamic equations for an effective p + 1-dimensional fluid yield solutions to the vacuum Einstein equations in a derivative expansion. Going beyond the perfect fluid approximation, we compute the effective shear and bulk viscosities of the black brane. The values we obtain saturate generic bounds. Sound waves in the effective fluid are unstable, and have been previously related to the Gregory-Laflamme instability of black p-branes. By including the damping effect of the viscosity in the unstable sound waves, we obtain a remarkably good and simple approximation to the dispersion relation of the Gregory-Laflamme modes, whose accuracy increases with the number of transverse dimensions. We propose an exact limiting form as the number of dimensions tends to infinity.
15140371
Black rings in Taub-NUT and D0-D6 interactions
We analyze the dynamics of neutral black rings in Taub-NUT spaces and their relation to systems of D0 and D6 branes in the supergravity approximation. We employ several recent techniques, both perturbative and exact, to construct solutions in which thermal excitations of the D0-branes can be turned on or off, and the D6-brane can have B-fluxes turned on or off in its worldvolume. By explicit calculation of the interaction energy between the D0 and D6 branes, we can study equilibrium configurations and their stability. We find that although D0 and D6 branes (in the absence of B fields, and at zero temperature) repeal each other at non-zero separation, as they get together they go over continuosly to an unstable bound state of an extremal singular Kaluza-Klein black hole. We also find that, for B-fields larger than a critical value, or sufficiently large thermal excitation, the D0 and D6 branes form stable bound states. The bound states with thermally excited D0 branes are black rings in Taub-NUT, and we provide an analysis of their phase diagram.
120114286
Transport and response coefficients in the blackfold approach
The blackfold approach is an effective theory for higher dimensional black holes. In this approach, black holes are described as materials: they are characterised by speeds of sound, viscosities and elastic moduli. These can be computed from first principles in general relativity by generalising techniques developed in AdS/CFT contexts. Apart from its intrinsic interest, this approach is a dramatic simplification of the Einstein equations that can be used to tackle important open problems of higher dimensional gravity.
53988734
Generalized entropy and higher derivative gravity
A bstractWe derive an extension of the Ryu-Takayanagi prescription for curvature squared theories of gravity in the bulk, and comment on a prescription for more general theories. This results in a new entangling functional, that contains a correction to Wald’s entropy. The new term is quadratic in the extrinsic curvature. The coefficient of this correction is a second derivative of the lagrangian with respect to the Riemann tensor. For Gauss-Bonnet gravity, the new functional reduces to Jacobson-Myers’.
56232513
Search for physics beyond the standard model via a polarization-asymmetry correlation experiment on In-107
We report on a new precision measurement of the longitudinal polarization of positrons emitted by polarized 107In nuclei. Preliminary results yield a lower limit of 303 GeV/c2 for the mass of a possible, predominantly right-handed, W gauge boson, if interpreted in the framework of the manifest, left-right symmetric model. In more general left-right symmetric models our result is complementary to those from muon decay experiments and to results from searches for a similar particle in collider experiments. Our data also provide new results on possible tensor contributions to the weak interaction.
125102842
Constraints on deviations from the standard model from a polarization-asymmetry correlation measurement with 107In
120424264
Bounds on right-handed currents from a relative beta-polarization measurement with polarized in-107
Abstract The first measurements of the longitudinal polarization of positrons emitted by polarized 107 In are reported. The positron polarization is deduced from the time-resolved decay spectrum of positronium hyperfine states. Our result is in agreement with the standard electro-weak model and provides a new lower limit for the mass of an eventual, predominantly right-handed charged W-gauge boson of 220 GeV/c 2 .
122363991
Helicity structure in low- and intermediate-energy weak interaction
Abstract We report on the status of the measurements of the longitudinal polarization of positrons emitted by polarized 107 In and 12 N nuclei. Present results yield a lower limit of 306 GeV/c 2 (90 % CL) for the mass of a possible W gauge boson with predominantly right-handed couplings, if interpreted in the framework of the manifest left-right symmetric model. In addition, the helicity structure of the weak interaction is discussed on the basis of experimental results at low and intermediate energies in the leptonic, semileptonic and hadronic sectors. Whereas in the minimal manifest left-right symmetric extension of the Standard Model the results from collider experiments are superior to results from other experiments, experiments in the three sectors of the weak interaction yield complementary information on the helicity structure of the interaction if interpreted in general left-right symmetric models.