1,449 research outputs found
Independent electrons model for open quantum systems: Landauer-Buettiker formula and strict positivity of the entropy production
A general argument leading from the formula for currents through an open
noninteracting mesoscopic system given by the theory of non-equilibrium steady
states (NESS) to the Landauer-Buettiker formula is pointed out. Time reversal
symmetry is not assumed. As a consequence it follows that, as far as the system
has a nontrivial scattering theory and the reservoirs have different
temperatures and/or chemical potentials, the entropy production is strictly
positive.Comment: 12 pages. Submitted for publication in J. Math. Phys. on 2006-06-05.
Revision and extension of: G. Nenciu, A general proof of Landauer-Buettiker
formula, [math-ph/0603030
Phenomenology of a Stabilized Modulus
We explore the phenomenology of a stabilized modulus field in the Randall-Sundrum scenario. It is found that if the large separation between branes arises from a small bulk scalar mass then the modulus is likely to be lighter than the lowest Kaluza-Klein excitations of bulk fields, and consequently may be the first direct signature of the model. Four-dimensional general covariance completely determines the couplings of the modulus to Standard Model fields. The strength of these couplings is determined by a single parameter which is set by the TeV rather than the Planck scale
The Lorentz integral transform (LIT) method
The LIT approach is reviewed both for inclusive and exclusive reactions. It
is shown that the method reduces a continuum state problem to a
bound-state-like problem, which then can be solved with typical bound-state
techniques. The LIT approach opens up the possibility to perform ab initio
calculations of reactions also for those particle systems which presently are
out of reach in conventional approaches with explicit calculations of many-body
continuum wave functions. Various LIT applications are discussed ranging from
particle systems with two nucleons up to particle systems with seven nucleons.Comment: Lectures delivered at the 4th DAE-BRNS Workshop on Hadron Physics,
AMU, Aligarh, India, Feb. 18-23, 2008; 23 pages, 16 figure
Radion effects on unitarity in gauge-boson scattering
The scalar field associated with fluctuations in the positions of the two
branes, the ``radion'', plays an important role determining the cosmology and
collider phenomenology of the Randall-Sundrum solution to the hierarchy
problem. It is now well known that the radion mass is of order the weak scale,
and that its couplings to standard model fields are order 1/TeV to the trace of
the energy momentum tensor. We calculate longitudinal vector boson scattering
amplitudes to explore the constraints on the radion mass and its coupling from
perturbative unitarity. The scattering cross section can indeed become
non-perturbative at energies prior to reaching the TeV brane cutoff scale, but
only when some curvature-Higgs mixing on the TeV brane is present. We show that
the coefficient of the curvature-Higgs mixing operator must be less than about
3 for the 4-d effective theory to respect perturbative unitarity up to the TeV
brane cutoff scale. Mass bounds on the Higgs boson and the radion are also
discussed.Comment: 17 pages, LaTeX, 5 eps figures, uses epsf.sty and axodraw.st
Bulk Fields in Delocalized Dilatonic p-Branes
We study localization properties of various bulk fields on a dilatonic
p-brane which is delocalized along its transverse directions except one. We
find that all the bosonic and fermionic bulk fields can be localized on the
delocalized dilatonic p-brane in a strict sense, namely the Kaluza-Klein zero
modes of the bulk fields are normalizable and are localized around the brane,
for any values of the dilaton coupling parameter.Comment: 9 pages, LaTe
The dynamics of the gravitational two-body problem at fourth post-Newtonian order and at quadratic order in the Newton constant
We derive the conservative part of the Lagrangian and the energy of a
gravitationally bound two-body system at fourth post-Newtonian order, up to
terms quadratic in the Newton constant. We also show that such terms are
compatible with Lorentz invariance and we write an ansatz for the
center-of-mass position. The remaining terms carrying higher powers of the
Newton constant are currently under investigation.Comment: 24 pages, 2 figures. Typos in formulae corrected, references added,
more comments in the conclusion in v
Some Properties of Domain Wall Solution in the Randall-Sundrum Model
Properties of the domain wall (kink) solution in the 5 dimensional
Randall-Sundrum model are examined both {\it analytically} and {\it
numerically}. The configuration is derived by the bulk Higgs mechanism. We
focus on 1) the convergence property of the solution, 2) the stableness of the
solution, 3) the non-singular property of the Riemann curvature, 4) the
behaviours of the warp factor and the Higgs field. It is found that the bulk
curvature changes the sign around the surface of the wall. We also present some
{\it exact} solutions for two simple cases: a) the no potential case, b) the
cosmological term dominated case. Both solutions have the (naked) curvature
singularity. We can regard the domain wall solution as a singularity resolution
of the exact solutions.Comment: Typographical error correction for publication. 16 pages, 4 figure
Scalar-Tensor Gravity in Two 3-brane System
We derive the low-energy effective action of four-dimensional gravity in the
Randall-Sundrum scenario in which two 3-branes of opposite tension reside in a
five-dimensional spacetime. The dimensional reduction with the Ansatz for the
radion field by Charmousis et al., which solves five-dimensional linearized
field equations, results in a class of scalar-tensor gravity theories. In the
limit of vanishing radion fluctuations, the effective action reduces to the
Brans-Dicke gravity in accord with the results of Garriga and Tanaka:
Brans-Dicke gravity with the corresponding Brans-Dicke parameter (for positive tension brane) and (for negative
tension brane). In general the gravity induced a brane belongs to a class of
scalar-tensor gravity with the Brans-Dicke parameter which is a function of the
interval and the radion. In particular, gravity on a positive tension brane
contains an attractor mechanism toward the Einstein gravity.Comment: 8 pages, discussion expanded, references adde
Higgs Mechanism and Bulk Gauge Boson Masses in the Randall-Sundrum Model
Assuming the breaking of gauge symmetries by the Higgs mechanism, we consider
the associated bulk gauge boson masses in the Randall-Sundrum background. With
the Higgs field confined on the TeV-brane, the W and Z boson masses can
naturally be an order of magnitude smaller than their Kaluza-Klein excitation
masses. Current electroweak precision data requires the lowest excited state to
lie above about 30 TeV, with fermions on the TeV-brane. This bound is reduced
to about 10 TeV if the fermions reside sufficiently close to the Planck-brane.
Thus, some tuning of parameters is needed. We also discuss the bulk Higgs case,
where the bounds are an order of magnitude smaller.Comment: 5 pages, 5 figures, using REVTeX, slightly expanded version to appear
in Phys. Rev.
Supersymmetric Randall-Sundrum Scenario
We present the supersymmetric version of the minimal Randall-Sundrum model
with two opposite tension branes.Comment: Latex, 9 pages. Published versio
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