121733272
Coherence effects on two-pion interferometry in ultra-high energy heavy-ion collisions
Abstract The effects of two kinds of coherent lengths, the wave packet length of the emitter and the radius of the coherent source, on two-pion interferometry are studied. It is shown that both coherent lengths can decrease the apparent radius of the source and cause abundant pions at low momentum.
120380312
Pion-interferometry analysis in relativistic heavy-ion collisions based on the VENUS model☆
Abstract The source size in relativistic heavy-ion collisions obtained by pion-interferometry analyses based on the VENUS model is compared with the actual source size of the model and experimental measurements. The predicted transverse source size is larger than the size of the projectile nuclei, but smaller than the preliminary findings from a recent experiment in the central rapidity region. The effect of rescattering on the source size is also discussed.
108059264
An active terminating pre-amplifier for delay line readout systems
118396278
Does the mass of a black hole decrease due to the accretion of phantom energy
According to Babichev et al., the accretion of a phantom test fluid onto a Schwarzschild black hole will induce the mass of the black hole to decrease, however the backreaction was ignored in their calculation. Using new exact solutions describing black holes in a background Friedmann-Robertson-Walker universe, we find that the physical black hole mass may instead increase due to the accretion of phantom energy. If this is the case, and the future universe is dominated by phantom dark energy, the black hole apparent horizon and the cosmic apparent horizon will eventually coincide and, after that, the black hole singularity will become naked in finite comoving time before the big rip occurs, violating the cosmic censorship conjecture.
18045161
What is the fate of a black hole embedded in an expanding universe
Abstract Within a large class of exact solutions of the Einstein equations describing a black hole embedded in a Friedmann universe it is shown that, under certain assumptions, only those with comoving Hawking–Hayward quasi-local mass are generic, in the sense that they are late-time attractors.
118647873
Cyclic universe due to phantom and quintessence
We explore a cyclic universe due to phantom and quintessence fields. We find that, in every cycle of the evolution of the universe, the phantom dominates the cosmic early history and quintessence dominates the cosmic far future. In this model of universe, there are infinite cycles of expansion and contraction. Different from the inflationary universe, the corresponding cosmic space-time is geodesically complete and quantum stable. But similar to the Cyclic Model, the flatness problem, the horizon problem and the large scale structure of the universe can be explained in this cyclic universe.
118387213
Generalized modified gravity with the second order acceleration equation
The National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China(Dated: October 30, 2012)In the theories of generalized modiﬁed gravity, the acceleration equation is generally fourth order.So it is hard to analyze the evolution of the Universe. In this paper, we present a class of generalizedmodiﬁed gravity theories which have the acceleration equation of second order derivative. Then boththe cosmic evolution and the weak-ﬁeld limit of the theories are easily investigated. We ﬁnd thatnot only the Big-bang singularity problem but also the current cosmic acceleration problem couldbe easily dealt with.