Gradient Flow in Logarithmic Conformal Field Theory

We establish conditions under which the worldsheet beta-functions of logarithmic conformal field theories can be derived as the gradient of some scalar function on the moduli space of running coupling constants. We derive a renormalization group invariant version of this function and relate it to the usual Zamolodchikov C-function expressed in terms of correlation functions of the worldsheet energy-momentum tensor. The results are applied to the example of D-brane recoil in string theory.Comment: 12 pages LaTeX; references updated, one added; to be published in Physics Letters

D-Brane Recoil Mislays Information

We discuss the scattering of a light closed-string state off a $D$ brane, taking into account quantum recoil effects on the latter, which are described by a pair of logarithmic operators. The light-particle and $D$-brane subsystems may each be described by a world-sheet with an external source due to the interaction between them. This perturbs each subsystem away from criticality, which is compensated by dressing with a Liouville field whose zero mode we interpret as time. The resulting evolution equations for the $D$ brane and the closed string are of Fokker-Planck and modified quantum Liouville type, respectively. The apparent entropy of each subsystem increases as a result of the interaction between them, which we interpret as the loss of information resulting from non-observation of the other entangled subsystem. We speculate on the possible implications of these results for the propagation of closed strings through a dilute gas of virtual $D$ branes.Comment: 34 pages, LaTeX, 2 figures (included

Forced flow evaporator for unusual gravity conditions

Low efficiency heat transfer in evaporators subject to unusual gravitational conditions is avoided through the use of a spiral evaporator conduit 12 receiving at an inlet 14 a vaporizable coolant at least partly in the liquid phase. Flow of the coolant through the conduit 12 demists the coolant by centrifuging the liquid phase against a pressurre wall 44 of the conduit 12. Vapor flow 40 induces counterrotating vortices 46, 48 which circulate the liquid phase coolant around the interior of the conduit 12 to wet all surfaces thereof

The Mean Ultraviolet Spectrum of a Representative Sample of Faint z~3 Lyman Alpha Emitters

We discuss the rest-frame ultraviolet emission line spectra of a large (~100) sample of low luminosity redshift z~3.1 Lyman alpha emitters (LAEs) drawn from a Subaru imaging survey in the SSA22 survey field. Our earlier work based on smaller samples indicated that such sources have high [OIII]/[OII] line ratios possibly arising from a hard ionising spectrum that may be typical of similar sources in the reionisation era. With optical spectra secured from VLT/VIMOS, we re-examine the nature of the ionising radiation in a larger sample using the strength of the high ionisation diagnostic emission lines of CIII]1909, CIV1549, HeII1640, and OIII]1661,1666 in various stacked subsets. Our analysis confirms earlier suggestions of a correlation between the strength of Ly-alpha and CIII] emission and we find similar trends with broad band UV luminosity and rest-frame UV colour. Using various diagnostic line ratios and our stellar photoionisation models, we determine both the gas phase metallicity and hardness of the ionisation spectrum characterised by xi_ion - the number of Lyman continuum photons per UV luminosity. We confirm our earlier suggestion that xi_ion is significantly larger for LAEs than for continuum-selected Lyman break galaxies, particularly for those LAEs with the faintest UV luminosities. We briefly discuss the implications for cosmic reionisation if the metal-poor intensely star-forming systems studied here are representative examples of those at much higher redshift.Comment: 15 pages, 9 figures. Accepted for publication in MNRA

Subaru Weak Lensing survey -- II: Multi-object Spectroscopy and Cluster Masses

We present the first results of a MOS campaign to follow up cluster candidates located via weak lensing. Our main goals are to search for spatial concentrations of galaxies that are plausible optical counterparts of the weak lensing signals, and to determine the cluster redshifts from those of member galaxies. Around each of 36 targeted cluster candidates, we obtain 15-32 galaxy redshifts. For 28 of these targets, we confirm a secure cluster identification. This includes three cases where two clusters at different redshifts are projected along the same line-of-sight. In 6 of the 8 unconfirmed targets, we find multiple small galaxy concentrations at different redshifts. In both the remaining two targets, a single small galaxy concentration is found. We evaluate the weak lensing mass of confirmed clusters. For a subsample of our most cleanly measured clusters, we investigate the statistical relation between their weak lensing mass and the velocity dispersion of their member galaxies, comparing our sample with optically and X-ray selected samples from the literature. Our lensing-selected clusters are consistent with sigma_v=sigma_sis, with a similar scatter to the optically and X-ray selected clusters. We thus find no evidence of selection bias compared to these other techniques. We also derive an empirical relation between the cluster mass and the galaxy velocity dispersion, which is in reasonable agreement with the prediction of N-body simulations in the LCDM cosmology.Comment: 58 pages, 45 figures, submitted to PASJ. A version with full-resolution figures is available at http://th.nao.ac.jp/~hamanatk/PP/supcam_wl2.pd

Fluorescent C II* 1335A emission spectroscopically resolved in a galaxy at z = 5.754

We report the discovery of the first spectroscopically resolved C II /C II* 1334, 1335A doublet in the Lyman-break galaxy J0215-0555 at z = 5.754. The separation of the resonant and fluorescent emission channels was possible thanks to the large redshift of the source and long integration time, as well as the small velocity width of the feature, 0.6 +- 0.2A. We model this emission and find that at least two components are required to reproduce the combination of morphologies of C II* emission, C II absorption and emission, and Lyman-alpha emission from the object. We suggest that the close alignment between the fluorescence and Lyman-alpha emission could indicate an ionisation escape channel within the object. While the faintness of such a C II /C II* doublet makes it prohibitively difficult to pursue for similar systems with current facilities, we suggest it can become a valuable porosity diagnostic in the era of JWST and the upcoming generations of ELTs.Comment: 5 pages, 3 figures; accepted for publication in MNRAS Letter

Book Reviews

Simple Justice: The History of Brown v. Board of Education and Black America\u27s Struggle for Equality By Richard Kluger Reviewed by Paul L. Murphy Richard Kluger is a novelist and editor who retired to devote his full time to an extensive study of the landmark Supreme Court decision of Brown v. Board of Education.\u27 Perceiving the Brown decision as a watershed with respect to America\u27s willingness to confront the consequences of centuries of racial discrimination, Kluger set out to tell the entire story of the Brown decision. Kluger approaches the Brown case not as a study of the law and its permutations, but as a study of how law and men interact, how social forces of the past collide with those of the present, and how the men selected as America\u27s ultimate arbiters of justice have chosen to define that quality with widely varying regard for the emotional content of life itself. \u27 ========================== American Lawyers in a Changing Society, 1776-1876 By Maxwell Bloomfield Reviewed by Richard E. Ellis This book has a number of virtues. It is fluently and, at times,even engagingly written. Its research is wide ranging. It is often suggestive. It is critical of other interpretations without being pretentious and arrogant. Yet, it is also a book with serious flaws. It lacks focus and balance, and it fails to elaborate adequately on its most important points. It frequently offers interpretations that are confusing and questionable, and, despite the promise of the title, it does not relate adequately the legal profession to the changing nature of American society in the hundred years after independence. ============================ Unequal Justice: Lawyers and Social Change in Modern America: By Jerold S. Auerbach. Reviewed by Sanford Levinson Jerold Auerbach, professor of American history at Wellesley College, has written an extremely valuable, but vexing, study of the social and political attitudes of America\u27s legal elite during the twentieth century. Its value lies in Auerbach\u27s demonstration of the social conservatism, at times sliding over into abject bigotry, that motivated many venerable leaders of the American Bar. Any image of the Bar as genuinely committed to meritocracy-the linking of Bar membership and leadership to attributes other than proper racial, religious, or social background-must collapse in the face of the evidence collected by Auerbach. Insofar as one value of historical understanding is simply the chastening of our tendency toward idealization of the past, Auerbach has performed a real service