6,446 research outputs found
Thermodynamics of Conformal Anomaly Corrected Black Holes in AdS Space
We present exact analytical black hole solutions with conformal anomaly in
AdS space and discuss the thermodynamical properties of these black hole
solutions. These black holes can have a positive, zero and negative constant
curvature horizon, respectively. For the black hole with a positive constant
curvature horizon, there exists a minimal horizon determined by the coefficient
of the trace anomaly, the black hole with a smaller horizon is
thermodynamically unstable, while it is stable for the case with a larger
horizon. The Hawking-Page transition happens in this case. For the black hole
with a Ricci flat horizon, the black hole is always thermodynamically stable
and there is no Hawking-Page transition. In the case of the black hole with a
negative constant curvature horizon, there exists a critical value for the
coefficient of the trace anomaly, under this critical value, the black hole is
always thermodynamical stable and the Hawking-Page transition does not happen.
When the coefficient is beyond the critical value, the black hole with a
smaller horizon is thermodynamically unstable, but it becomes stable for the
case with a larger horizon, the Hawking-Page transition always happens in this
case. The latter is a new feature for the black holes with a negative constant
curvature horizon.Comment: Letax, 17 pages with 6 figure
Dynamics and thermodynamics of a probe brane in the multicenter and rotating D3-brane background
We study the dynamics and thermodynamics of a probe D3-brane in the rotating
D3-brane background and in its extremal limit, which is a multicenter
configuration of D3-branes distributed uniformly on a disc. In the extremal
background, if the angular momentum of the probe does not vanish, the probe is
always bounced back at some turning point. When its angular momentum vanishes,
in the disc plane, the probe will be captured at the edge of the disc; in the
hyperplane orthogonal to the disc, the probe will be absorbed at the center of
the disc. In the non-extremal background, if the probe is in the hyperplane
orthogonal to the disc, it will be captured at the horizon; if the probe is
restricted in the disc plane, the probe will be bounced back at a turning
point, which is just the infinite red-shift hyperplane of the rotating
background, even when the angular momentum of the probe vanishes. The
thermodynamics of a relative static D3-brane probe is also investigated to the
rotating D3-brane source. Two critical points are found. One is just the
thermodynamically stable boundary of the source rotating D3-branes; the other
is related to the distance between the probe and the source, which can be
regarded as the mass scale in the corresponding super Yang-Mills theory. If the
probe is static, the second critical point occurs as the probe is at the
infinite red-shift hyperplane of the background. The relevance to the
thermodynamics of the super Yang-Mills theory is discussed briefly.Comment: Revtex, 16 pages, no figures, minor change
A Note on Curvature Fluctuation of Noncommutative Inflation
An elegant approach, which incorporates the effect of the stringy spacetime
uncertainty relation, to calculate power spectra of fluctuations during
inflation has been suggested by Brandenberger and Ho. In this approach, one of
important features is the appearance of an upper bound on the comoving momentum
, at which the stringy spacetime uncertainty relation is saturated. As a
result, the time-dependent upper bound leads us to choose naturally a set of
initial vacua for each mode, in which the stringy uncertainty relation is
saturated. In this note, with that set of vacua we calculate power spectrum of
curvature fluctuation for a power law inflation, up to the leading order of a
parameter describing the spacetime noncommutativity. It turns out that this
choice of initial vacuum has a significant effect on the power spectrum of
fluctuations.Comment: Latex, 13 pages, v2: minor changes, two references added, to appear
in PL
A New Model of Agegraphic Dark Energy
In this note, we propose a new model of agegraphic dark energy based on the
K\'{a}rolyh\'{a}zy relation, where the time scale is chosen to be the conformal
time of the Friedmann-Robertson-Walker (FRW) universe. We find that in
the radiation-dominated epoch, the equation-of-state parameter of the new
agegraphic dark energy whereas ; in the
matter-dominated epoch, whereas ; eventually, the
new agegraphic dark energy dominates; in the late time when
, and the new agegraphic dark energy mimics a cosmological
constant. In every stage, all things are consistent. The confusion in the
original agegraphic dark energy model proposed in arXiv:0707.4049 disappears in
this new model. Furthermore, is naturally satisfied in both
radiation-dominated and matter-dominated epochs where . In addition, we
further extend the new agegraphic dark energy model by including the
interaction between the new agegraphic dark energy and background matter. In
this case, we find that can cross the phantom divide.Comment: 8 pages, revtex4; v2: Phys. Lett. B in press; v3: published versio
(F1, D1, D3) Bound State, Its Scaling Limits and SL(2,Z) Duality
We discuss the properties of the bound state (F1, D1, D3) in IIB supergravity
in three different scaling limits and the transformation of the
resulting theories. In the simple decoupling limit with finite electric and
magnetic components of NS field, the worldvolume theory is the =4
super Yang-Mills (SYM) and the supergravity dual is still the . In the large magnetic field limit with finite electric field, the theory
is the noncommutative super Yang-Mills (NCSYM), and the supergravity dual is
the same as that without the electric background. We show how to take the
decoupling limit of the closed string for the critical electric background and
finite magnetic field, and that the resulting theory is the noncommutative open
string (NCOS) with both space-time and space-space noncommutativities. It is
shown that under the transformation, the SYM becomes itself
with a different coupling constant, the NCSYM is mapped to a NCOS, and the NCOS
in general transforms into another NCOS and reduces to a NCSYM in a special
case.Comment: 20 pages, Latex, minor corrections, final version to appear in Prog.
Theor. Phy
- …