Quantization in black hole backgrounds

Quantum field theory in a semiclassical background can be derived as an approximation to quantum gravity from a weak-coupling expansion in the inverse Planck mass. Such an expansion is studied for evolution on "nice-slices" in the spacetime describing a black hole of mass M. Arguments for a breakdown of this expansion are presented, due to significant gravitational coupling between fluctuations, which is consistent with the statement that existing calculations of information loss in black holes are not reliable. For a given fluctuation, the coupling to subsequent fluctuations becomes of order unity by a time of order M^3. Lack of a systematic derivation of the weakly-coupled/semiclassical approximation would indicate a role for the non-perturbative dynamics of gravity, and possibly for the proposal that such dynamics has an essentially non-local quality.Comment: 28 pages, 4 figures, harvmac. v2: added refs, minor clarification

Dynamics of Extremal Black Holes

Particle scattering and radiation by a magnetically charged, dilatonic black hole is investigated near the extremal limit at which the mass is a constant times the charge. Near this limit a neighborhood of the horizon of the black hole is closely approximated by a trivial product of a two-dimensional black hole with a sphere. This is shown to imply that the scattering of long-wavelength particles can be described by a (previously analyzed) two-dimensional effective field theory, and is related to the formation/evaporation of two-dimensional black holes. The scattering proceeds via particle capture followed by Hawking re-emission, and naively appears to violate unitarity. However this conclusion can be altered when the effects of backreaction are included. Particle-hole scattering is discussed in the light of a recent analysis of the two-dimensional backreaction problem. It is argued that the quantum mechanical possibility of scattering off of extremal black holes implies the potential existence of additional quantum numbers - referred to as ``quantum whiskers'' - characterizing the black hole.Comment: 31 page

Trajectories of Offending from Childhood to Early Adulthood in Girls With and Without Mental Health System Involvement

Criminology literature is overwhelmingly based in studies of males, though studies of gender differences or of females are rapidly accumulating. Rates of psychiatric disorder are typically higher in females involved with justice systems compared to males. However, the juvenile or criminal justice involvement of girls in mental health systems, or with serious mental health conditions is greatly understudied. Identifying their arrest risk onset, peak, and offset provides practitioners information about when to intervene and with whom. The goal of the present study is to describe within-individual longitudinal arrest patterns from ages 8-24 in this population, and determine whether their arrest patterns differ from general offender females in ways that have practice implications. Methods: Using statewide administrative data from the Massachusetts Department of Mental Health (DMH) and Massachusetts’ juvenile and criminal courts, a database was constructed that contained juvenile and criminal arrest histories to age 25 for females born 1976-79. DMH females were adolescent service users (n=738), Non-DMH females had no DMH database records (n=34,436). Massachusetts Census 2000 provided the size of the general female population. Developmental trajectory modeling was used to group individuals’ patterns of offending over time (trajectories) into “clusters” of those whose trajectories are similar, and describe trajectories. Trajectory comparison methods minimized the greater Non-DMH cohort size. Results: DMH females were far more likely to be arrested by age 25 than Non-DMH females (46% vs. 22%) and to be arrested at multiple ages (28% vs. 7%). Analyses revealed eight justice system trajectories among those with multiple ages of arrest. Trajectories varied on level of involvement and timing of onset/offset/peaks. Non-DMH females comprised at least 93% of each trajectory cluster, though several clusters showed significant over- or under-representation of DMH females. Conclusions: Concern about justice system involvement of female youths in intensive MH services is justified. Among girls with multiple ages with arrest, differences in criminal careers between the mental health and non mental health system users was minimal. Implications of trajectory findings for timing and type of intervention will be presented

Temporal Patterns of Arrest in a Cohort of Adults Receiving Mental Health Services: The Massachusetts Mental Health / Criminal Justice Cohort Study

Criminal Justice Involvement among Clientele is a Major Concern for State Mental Health Agencies. Mental health and criminal justice systems provide services at various points along the interface of these systems to reduce offending and re-offending, including: - Diversion programs - Mental Health Courts - Re-Entry Little information about scope of offending to guide service development. This study provides data on the prevalence, type and temporal patterns of arrest for a large sample of adults followed for roughly 9.5 years

Serious Mental Illness and Chronic Crimial Justice Involvement: Findings from The Massachusetts Mental Healthy / Criminal Justice Cohort Study

Presents findings from 1990 through 2000 from The Massachusetts Mental Health/Criminal Justice Cohort Study

Quantum Theories of Dilaton Gravity

Quantization of two-dimensional dilaton gravity coupled to conformal matter is investigated. Working in conformal gauge about a fixed background metric, the theory may be viewed as a sigma model whose target space is parameterized by the dilaton $\phi$ and conformal factor $\rho$. A precise connection is given between the constraint that the theory be independent of the background metric and conformal invariance of the resulting sigma model. Although the action is renormalizable, new coupling constants must be specified at each order in perturbation theory in order to determine the quantum theory. These constants may be viewed as initial data for the beta function equations. It is argued that not all choices of this data correspond to physically sensible theories of gravity, and physically motivated constraints on the data are discussed. In particular a recently constructed subclass of initial data which reduces the full quantum theory to a soluble Liouville-like theory has energies unbounded from below and thus is unphysical. Possibilities for modifying this construction so as to avoid this difficulty are briefly discussed.Comment: 20 pages (Major additions made, including 5 pages on the relation between conformal invariance and background independence.

Entropy in Black Hole Pair Production

Pair production of Reissner-Nordstrom black holes in a magnetic field can be described by a euclidean instanton. It is shown that the instanton amplitude contains an explicit factor of $e^{A/4}$, where $A$ is the area of the event horizon. This is consistent with the hypothesis that $e^{A/4}$ measures the number of black hole states.Comment: 24 pages (harvmac l mode

A lattice study of the two-dimensional Wess Zumino model

We present results from a numerical simulation of the two-dimensional Euclidean Wess-Zumino model. In the continuum the theory possesses N=1 supersymmetry. The lattice model we employ was analyzed by Golterman and Petcher in \cite{susy} where a perturbative proof was given that the continuum supersymmetric Ward identities are recovered without finite tuning in the limit of vanishing lattice spacing. Our simulations demonstrate the existence of important non-perturbative effects in finite volumes which modify these conclusions. It appears that in certain regions of parameter space the vacuum state can contain solitons corresponding to field configurations which interpolate between different classical vacua. In the background of these solitons supersymmetry is partially broken and a light fermion mode is observed. At fixed coupling the critical mass separating phases of broken and unbroken supersymmetry appears to be volume dependent. We discuss the implications of our results for continuum supersymmetry breaking.Comment: 32 pages, 12 figure