117461065
Mathematical aspects of the Hawking effect.
122974723
Linear stability of Schwarzschild under perturbations which are non-vanishing on the bifurcation 2-sphere
The authors prove boundedness on an exterior Schwarzschild wedge for Cinfinity solutions of the covariant Klein-Gordon equation which have compact support on Cauchy surfaces in Kruskal spacetime. Previously used methods enable such boundedness to be proven only for solutions whose initial data satisfy the additional restriction of vanishing at the bifurcation 2-sphere of the horizon. By employing a rarely considered discrete isometry of Kruskal spacetime and the causal propagation property of the equation, they remove this restriction. This also enables them to prove boundedness exterior to the horizon of a spacetime representing the collapse to a black hole of a spherically symmetric compact star for solutions of the same equation having Cinfinity initial data on a Cauchy surface drawn prior to the collapse.
5060903
Monotonicity with volume of entropy and of mean entropy for translationally invariant systems as consequences of strong subadditivity
We consider some questions concerning the monotonicity properties of entropy and of mean entropy for translationally invariant states on translationally invariant systems (classical lattice, quantum lattice and quantum continuous). By taking the property of strong subadditivity, which for quantum systems was proven rather late in the historical development, as one of four primary axioms (the other three being simply positivity, subadditivity and translational invariance), we are able to obtain results, some new, some proved in a new way, which appear to complement in an interesting way results proved around 30 years ago on limiting mean entropy and related questions. In particular, we prove that as the sizes of boxes in Z ν or R ν increase in the sense of set inclusion, (1) their mean entropy decreases monotonically and (2) their entropy increases monotonically. We include a proof of (2) based on the notion of mpoint correlation entropies, which we introduce and which generalize the notion of index of correlation (see e.g. Horodecki R 1994 Phys. Lett. A 187 145). We mention a number of further results and questions concerning monotonicity of entropy and of mean entropy for more general shapes than boxes and for more general translationally invariant (/homogeneous) lattices and spaces than Z ν or R ν . We also obtain some further results on monotonicity of entropy in these more general situations by adjoining a fifth axiom, which embodies yet another general property of entropy (which we call the ‘strong triangle inequality’).
124668258
Purification of Kms States
On presente des resultats fondamentaux sur les etats KMS a partir d'une approche nouvelle suggeree a la fois par le probleme de purification et aussi par la situation de Bisognano-Wichmaun
117805675
Entropy Defined, Entropy Increase and Decoherence Understood, and Some Black-Hole Puzzles Solved
Statistical mechanics explains thermodynamics in terms of (quantum) mechanics by equating the entropy of a microstate of a closed system with the logarithm of the number of microstates in the macrostate to which it belongs, but the question `what is a macrostate?' has never been answered except in a vague, subjective, way. However Hawking's discovery of black hole evaporation led to a formula for black hole entropy with no subjective element. In this letter, we argue from this result, together with the assumption that `black hole thermodynamics is just ordinary thermodynamics applied to black holes', that a macrostate for a general (quantum gravitational) closed system is an equivalence class of matter-gravity microstates with the same expectation values for the matter degrees of freedom alone. Not only does this finally answer the question `what is entropy?', but it also predicts the equality of the thermodynamic entropy of a black hole with the matter and the gravity entropy-like quantities derived from the Euclidean path integral. Furthermore it gives us a clear glimpse of an ultimate synthesis of quantum theory and gravity in which we see that (a) gravity acts as a universal environment, thus predicting that, if the initial state of the universe is unentangled, its entropy must go on increasing forever, (b) the gravitational field has degrees of freedom, but no observables, thus enabling gravity to perform the trick of providing an objective continual process of decoherence. All the above rests on the validity of unitarity. The `information-loss puzzle' had raised doubts about that. But we suggest a resolution for this puzzle.
119983228
Renormalization of semiclassical field theories
Abstract We discuss a simple model which shares some of the essential features of the semiclassical theory of gravitation. In this model, a classical scalar field υ interacts with a quantized field φ. We describe a consistent and unambiguous renormalization scheme for the model.
118976996
One-neutron knockout in the vicinity of the N=32 sub-shell closure: Be-9(Cr-57,Cr-56+gamma)X
Gade, A. Janssens, R. V. F. Bazin, D. Brown, B. A. Campbell, C. M. Carpenter, M. P. Cook, J. M. Deacon, A. N. Dinca, D. -C. Freeman, S. J. Glasmacher, T. Horoi, M. Kay, B. P. Mantica, P. F. Mueller, W. F. Terry, J. R. Tostevin, J. A. Zhu, S.
13327837
First experiment with HELIOS: the structure of 13B.
A first experiment is reported that makes use of a new kind of spectrometer uniquely suited to the study of reactions with radioactive beams in inverse kinematics, the helical orbit spectrometer, HELIOS. The properties of some low-lying states in the neutron-rich N=8 nucleus 13B were studied with good resolution. From the measured angular distributions of the (d,p) reaction and the relative spectroscopic factors, spin and configuration assignments of the first- and third-excited states of this nucleus can be constrained.