119233085
Quasinormal Modes of Charged Fermions and Phase Transition of Black Holes
We study the quasinormal modes of massless charged fermions in a Reissner-Nordstrom-anti-de Sitter black hole spacetime. In the probe limit, we find that the imaginary part of quasinormal frequency will become positive when the temperature of the black hole is below a critical value. This indicates an instability of the black hole occurs and a phase transition happens. In the AdS/CFT correspondence, this transition can be viewed as a superconducting phase transition and the bulk fermion is regarded as the order parameter. When the coupling of the fermions and the background electric field becomes stronger, the critical temperature of the phase transition becomes higher. If the interaction between the fermion and the electric field can be ignored, namely in the case of a neutral fermion, the imaginary part of the quasinormal modes is always negative, which indicates that the black hole is stable and no phase transition occurs.
30079794
Stability of the event horizon in (2+1)-dimensional black holes.
119186601
Various types of phase transitions in the AdS soliton background
We study the basic holographic insulator and superconductor phase transition in the AdS soliton background by generalizing the spontaneous breaking of a global U(1) symmetry to occur via Stuckelberg mechanism. We construct the soliton solutions with backreaction and examine the effects of the backreaction on the condensation of the scalar hair in the generalized Stuckelberg Lagrangian. We disclose rich physics in various phase transitions. In addition to the AdS soliton configuration, we also examine the property of the phase transition in the AdS black hole background.
118997018
Probing the curvature of the Universe from supernova measurement
We study the possibility to probe the spatial geometry of the Universe by supernova measurement. We illustrate with an accelerating universe model with infinite-volume extra dimensions, for which the 1σ level supernova results indicate that the Universe is closed.
124897627
Different Quantum Entropies for Two Kinds of Extreme Two-Dimensional Lowe–Strominger Black Holes*
It is shown that both the classical entropy of two-dimensional extremal Lowe–Strominger black hole and the quantum entropy of the scalar field in the background of this black hole are different by using Hawking's treatment as wel as Zaslavskii's treatment respectively. This result supports our previous suggestion that there are two kinds of extreme black holes in the nature. A new divergent term emerges in the quantum entropy in Zaslavskii's treatment and its physical meaning has been discussed.
118198563
Dark Energy: Relating the Evolutions of the Universe from the Past to the Future
Using the evolution history of the universe, one can make constraint on the parameter space of dynamic dark energy models. We discuss two different parameterized dark energy models. Our results further restrict the combined constraints obtained from supernova and the first-year Wilkinson-microwave-anisotropy-probe observations. From the allowed parameter space, it is found that our universe will experience an eternal acceleration. We also estimate the bound on the physically relevant regions both in the re-inflationary and inflationary phases.
121864290
A compact positron annihilation lifetime spectrometer
Using LYSO scintillator coupled on HAMAMATSU R9800 (a fast photomultiplier) to form the small size gamma-ray detectors, a compact lifetime spectrometer has been built for the positron annihilation experiments. The system time resolution FWHM=193 ps and the coincidence counting rate similar to 8 cps/mu Ci were achieved. A lifetime value of 219 +/- 1 ps of positron annihilation in well annealed Si was tested, which is in agreement with the typical values published in the previous lectures.
121071019
OBSERVATIONAL H(z) DATA AS A COMPLEMENTARITY TO OTHER COSMOLOGICAL PROBES
In this paper, we use a set of observational H(z) data (OHD) to constrain the Lambda CDM cosmology. This dataset can be derived from the differential ages of the passively evolving galaxies. Meanwhile, the A-parameter, which describes the Baryonic Acoustic Oscillation (BAO) peak, and the newly measured value of the Cosmic Microwave Background (CMB) shift parameter Rare used to present combinational constraints on the same cosmology. The combinational constraints favor an accelerating flat universe while the flat Lambda CDM cosmology is also analyzed in the same way. We obtain result compatible with that by many other independent cosmological observations. We find that the observational H(z) data set is a complementarity to other cosmological probes.
121908282
QSO heavy-element absorption line systems and large galactic halos by satellite accretion
Recent observations indicate that the QSO heavy-element absorption line (HEAL) systems are associated with extremely large galactic halos. The origin of the absorbing gas, however, is not well understood. We demonstrate that an extremely large star formation rate is required if the HEAL gas originates from galactic disks. This is clearly incompatible with the observed moderate evolution and the normal colors of the galaxies associated with the Mg II absorption lines (MgALs). Studies of the H I high-velocity clouds, the Magellanic Stream, and recent observations of nearby QSOs suggest that the gas tidally torn out from the LMC/SMC system may be responsible for the MgALs observed in the Galactic halo
120034276
de Broglie–Bohm interpretation for wave function of a toroidal black hole
The mass function of a toroidal black hole as a dynamical variable is given by using Kuchar’s approach. Then the toroidal black hole is investigated by using the de Broglie–Bohm approach, and its quantum potential and quantum trajectories are obtained. In our process the vector potential of the electromagnetic field in the toroidal black hole is treated as a canonical variable.
121278811
Entropies of a Toroidal Black Hole Due to Scalar and Dirac Fields
Using the thin film brick-wall model, the entropies of a toroidal black hole due to scalar and Dirac fields are investigated. The entropy due to the scalar field is one fourth of the horizon area, and that due to the Dirac field is seven eighth of the area. These results are similar to that in black holes with horizon topology S2. The cutoff in toroidal black hole is chosen as the same as one in black holes with horizon topology S2, which seems to mean that the thin film brick-wall model is universal.