193 research outputs found
Emergent Symmetry on Black Hole Horizons
For a stationary and axisymmetric black hole, there is a natural way to split
the fields into a probe sector and a background sector. The equations of motion
for the probe sector enjoy a significantly enhanced symmetry on the black hole
horizon. The extended symmetry is conformal in four dimensions, while in higher
dimensions it is much bigger. This puts conformal symmetry at the bottom of the
ladder of symmetries that can arise on black hole horizons in generic
dimensions.Comment: 8 page
Fluctuating Black Hole Horizons
In this paper we treat the black hole horizon as a physical boundary to the
spacetime and study its dynamics following from the Gibbons-Hawking-York
boundary term. Using the Kerr black hole as an example we derive an effective
action that describes, in the large wave number limit, a massless Klein-Gordon
field living on the average location of the boundary. Complete solutions can be
found in the small rotation limit of the black hole. The formulation suggests
that the boundary can be treated in the same way as any other matter
contributions. In particular, the angular momentum of the boundary matches
exactly with that of the black hole, suggesting an interesting possibility that
all charges (including the entropy) of the black hole are carried by the
boundary. Using this as input, we derive predictions on the Planck scale
properties of the boundary.Comment: References added, nature of boundary stress tensor clarified,
discussion of statistics refined and a mistake with Hawking temperature
corrected, 16 pages; version to appear in journa
Towards A Possible Fluid Flow Underlying the Kerr Spacetime
Based on the idea of emergent spacetime, we consider the possibility that the
material underlying our spacetime is modelled by a fluid. We are particularly
interested in possible connections between the geometrical properties of the
emergent spacetime and the properties of the underlying fluid. We find some
partial results that support this possibility. By using the Kerr spacetime as
an example, we construct from the Riemann curvature tensor a vector field,
which behaves just like the speculated fluid flow.Comment: A mistake corrected, results improved, paper fully revised to account
for the change. 12 page
Radiative Corrections to Democratic Lepton Mixing
A new ansatz of democratic lepton mixing is proposed at the GUT scale and the
radiative corrections to its phenomenological consequences are calculated at
the electroweak scale. We demonstrate that it is possible to obtain the
experimentally favored results for both neutrino masses and lepton flavor
mixing angles from this ansatz, provided the neutrino Yukawa coupling matrix
takes a specific nontrivial pattern. The seesaw threshold effects play a
significant role in the running of relevant physical quantities.Comment: 10 pages (1 table, 2 figures). More discussions added. Phys. Lett. B
in pres
Conformal Symmetries of the Einstein-Hilbert Action on Horizons of Stationary and Axisymmetric Black Holes
We suggest a way to study possible conformal symmetries on black hole
horizons. We do this by carrying out a Kaluza-Klein like reduction of the
Einstein-Hilbert action along the ignorable coordinates of stationary and
axisymmetric black holes. Rigid diffeomorphism invariance of the -ignorable
coordinates then becomes a global gauge symmetry of the reduced
action. Related to each non-vanishing angular velocity there is a particular
subgroup, which can be extended to the Witt algebra on the black hole
horizons. The classical Einstein-Hilbert action thus has -copies of infinite
dimensional conformal symmetries on a given black hole horizon, with being
the number of non-vanishing angular velocities of the black hole.Comment: A demonstration of the first law of black hole thermodynamics is
added to section 3; and the introduction section is thoroughly revised; 22
page
Critical exponents of finite temperature chiral phase transition in soft-wall AdS/QCD models
Criticality of chiral phase transition at finite temperature is investigated
in a soft-wall AdS/QCD model with symmetry,
especially for and . It is shown that in quark mass
plane() chiral phase transition is second order at a certain
critical line, by which the whole plane is divided into first order and
crossover regions. The critical exponents and , describing
critical behavior of chiral condensate along temperature axis and light quark
mass axis, are extracted both numerically and analytically. The model gives the
critical exponents of the values and
for and respectively. For
, in small strange quark mass() region, the phase transitions for
strange quark and quarks are strongly coupled, and the critical exponents
are ; when is larger than
, the dynamics of light flavors() and strange
quarks decoupled and the critical exponents for and
becomes , exactly the same as result and
the mean field result of 3D Ising model; between the two segments, there is a
tri-critical point at , at which
. In some sense, the current results is still at mean
field level, and we also showed the possibility to go beyond mean field
approximation by including the higher power of scalar potential and the
temperature dependence of dilaton field, which might be reasonable in a full
back-reaction model. The current study might also provide reasonable
constraints on constructing a realistic holographic QCD model, which could
describe both chiral dynamics and glue-dynamics correctly.Comment: 32 pages, 11 figures, regular articl
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