119494487
REAL-TIME NONEQUILIBRIUM DYNAMICS IN HOT QED PLASMAS
The quantum kinetics of photons in hot QED plasmas is studied directly in real time by implementing the dynamical renormalization group. In contrast to conventional approach, the dynamical renormalization group method consistently includes off-shell (energy non-conserving) effects and accounts for time-dependent collisional kernel. To lowest order we find that in the relaxation time approximation the semihard photon distribution function relaxes with a power law.
19299796
Induced Einstein-Kalb-Ramond theory and the black hole.
A four-dimensional induced Einstein-Kalb-Ramond theory with a conformally coupled Kalb-Ramond term is discussed. It is argued that the Kalb-Ramond field is difficult to interpret as an axion field from a dynamical point of view, and hence tends to be unstable. One can, however, apply Routh's method to extract an effective action for the axion field. It is found that the Kalb-Ramond hair will turn the event horizon into a naked singularity. Such an exact solution is found and analyzed carefully. \textcopyright{} 1996 The American Physical Society.
121988198
A new analytical method for testing quantum entanglement in P→VV decay
Abstract As the basic criterion of the validity of quantum mechanics, Bell's inequality has aroused wide theoretical and experimental interest. With the accumulation of an increasing number of events in high-energy physics, it is tempting to test Bell's inequality directly in particle physics. In this paper, we choose the P → VV decay to reveal entanglement between daughter particles. On the basis of quantum mechanics predictions in the literature, we present a statistical method that can fully utilize the data available. A Monte Carlo simulation was carried to study the effects of detector geometry, detector efficiency and momentum resolution.
124472455
Search for diphoton events with large missing transverse momentum in 7 TeV proton-proton collision data with the ATLAS detector
A search for diphoton events with large missing transverse momentum has been performed using proton-proton collision data at is root s = 7 TeV recorded with the ATLAS detector, corresponding to an integrated luminosity of 4.8 fb(-1). No excess of events was observed above the Standard Model prediction and model-dependent 95% confidence level exclusion limits are set. In the context of a generalised model of gauge-mediated supersymmetry breaking with a bino-like lightest neutralino of mass above 50 GeV, gluinos (squarks) below 1.07 TeV (0.87 TeV) are excluded, while a breaking scale Lambda below 196 TeV is excluded for a minimal model of gauge-mediated supersymmetry breaking. For a specific model with one universal extra dimension, compactification scales 1/R < 1.40 TeV are excluded. These limits provide the most stringent tests of these models to date. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
18834437
Challenges to the DGP model from horizon-scale growth and geometry
We conduct a Markov Chain Monte Carlo study of the Dvali-Gabadadze-Porrati (DGP) selfaccelerating braneworld scenario given the cosmic microwave background (CMB) anisotropy, supernovae and Hubble constant data by implementing an effective dark energy prescription for modified gravity into a standard Einstein-Boltzmann code. We find no way to alleviate the tension between distance measures and horizon scale growth in this model. Growth alterations due to perturbations propagating into the bulk appear as excess CMB anisotropy at the lowest multipoles. In a flat
16310685
Young Stellar Groups around Herbig Ae/Be Stars: A Low-Mass YSO Census
We present near-IR and mid-IR observations of eight embedded young stellar groups around Herbig Ae/Be stars (HAEBEs) using archived Spitzer IRAC data and 2MASS data. These young stellar groups are nearby (≤1 kpc) and still embedded within their molecular clouds. In order to identify the young stellar objects in our sample, we use the color-color diagram of J - [3.6] versus Ks - [4.5]. The Spitzer images of our sample show that the groups around HAEBEs, spectral types earlier than B8, are usually associated with bright infrared nebulosity. Within this, there are normally 10-50 young stars distributed close to the HAEBEs (<1 pc). Not only are there young stars around the HAEBEs, there are also young stellar populations throughout the whole cloud, some of which are distributed and some of which are clumped. The groups around the HAEBEs are substructures of the large young population within the molecular cloud. The sizes of groups are also comparable with those substructures seen in massive clusters. Young stars in groups around HAEBEs have generally larger SED slopes compared to those outside, which suggests that the young stars in groups are probably younger than the distributed systems. This might imply that there is usually a higher and more continuous star-forming rate in groups, that the formation of groups initiates later, or that low-mass stars in groups form slower than those outside. Finally, there is no obvious trend between the SED slopes and the distance to the HAEBEs for those young stars within the groups. This suggests that the clustering of young stars dominates over the effect of massive stars on the low-mass young stars at the scale of our study.
121137429
The CDF Cherenkov luminosity monitor
Abstract We have built a novel device for precision measurements of luminosity in the CDF experiment at the high p p collision rates expected during Run II. The detector consists of long, conical, gaseous Cherenkov counters that point to the collision region and monitor the average number of inelastic p p interactions by measuring the number of particles, and their arrival time, in each bunch crossing. For these primary particles, using isobutane at atmospheric pressure as a radiator, a large amount of Cherenkov light (∼100 photoelectrons) will be collected, with good amplitude and time resolutions, onto small and efficient PMTs. Suitable amplitude thresholds will be applied to discriminate from non-primary particles and other backgrounds which yield little light in the counters. This detector is expected to reliably perform bunch-by-bunch luminosity measurements at peak instantaneous luminosities of 2×10 32  cm −2  s −1 with six interactions per bunch crossing, on average, and respond to a 132 ns bunch spacing.