1,511 research outputs found
Bimerons in Double Layer Quantum Hall Systems
In this paper we discuss bimeron pseudo spin textures for double layer
quantum hall systems with filling factor . Bimerons are excitations
corresponding to bound pairs of merons and anti-merons.
Bimeron solutions have already been studied at great length by other groups
by minimising the microsopic Hamiltonian between microscopic trial
wavefunctions. Here we calculate them by numerically solving coupled nonlinear
partial differential equations arising from extremisation of the effective
action for pseudospin textures. We also calculate the different contributions
to the energy of our bimerons, coming from pseudospin stiffness, capacitance
and coulomb interactions between the merons. Apart from augmenting earlier
results, this allows us to check how good an approximation it is to think of
the bimeron as a pair of rigid objects (merons) with logarithmically growing
energy, and with electric charge . Our differential equation
approach also allows us to study the dependence of the spin texture as a
function of the distance between merons, and the inter layer distance. Lastly,
the technical problem of solving coupled nonlinear partial differential
equations, subject to the special boundary conditions of bimerons is
interesting in its own right.Comment: 8 ps figures included; to be published in IJMP
Near Horizon Superspace
The adS_{p+2} x S^{d-p-2} geometry of the near horizon branes is promoted to
a supergeometry: the solution of the supergravity constraints for the vielbein,
connection and form superfields are found. This supergeometry can be used for
the construction of new superconformal theories. We also discuss the
Green-Schwarz action for a type IIB string on adS_5 x S_5.Comment: 11 pages, LaTe
Models and Phenomenology of Maximal Flavor Violation
We consider models of maximal flavor violation (MxFV), in which a new scalar
mediates large q_3 q_1 or q_3 q_2 flavor changing transitions (q_i is
an i'th generation quark), while q_3 q_3 transitions are suppressed, e.g.,
\xi_{31}, \xi_{13} ~ V_{tb} and \xi_{33} ~ V_{td}, where \xi_{ij} are the new
scalar couplings to quarks and V is the CKM matrix. We show that, contrary to
the conventional viewpoint, such models are not ruled out by the existing low
energy data on K^0, B^0 and D^0 oscillations and rare K and B-decays. We also
show that these models of MxFV can have surprising new signatures at the LHC
and the Tevatron.Comment: Latex, 4 pages, 1 figure. Version as publishe
New Branes and Boundary States
We examine D-branes on , and find a three-brane wrapping the entire
, in addition to 1-branes and instantonic 2-branes previously discussed
in the literature. The three-brane is found using a construction of Maldacena,
Moore, and Seiberg. We show that all these branes satisfy Cardy's condition and
extract the open string spectrum on them.Comment: 18 pages, late
Bounds on Unparticles from the Higgs Sector
We study supersymmetric QCD in the conformal window as a laboratory for
unparticle physics, and analyze couplings between the unparticle sector and the
Higgs sector. These couplings can lead to the unparticle sector being pushed
away from its scale invariant fixed point. We show that this implies that low
energy experiments will not be able to see unparticle physics, and the best
hope of seeing unparticles is in high energy collider experiments such as the
Tevatron and the LHC. We also demonstrate how the breaking of scale invariance
could be observed at these experiments.Comment: 9 pages, 3 figure
Analysis of nonperturbative fluctuations in a triple-well potential
We consider the quantum tunneling phenomenon in a well-behaved triple-well
potential. As required by the semiclassical approximation we take into account
the quadratic fluctuations over the instanton which represents as usual the
localised finite-action solution of the euclidean equation of motion. The
determinants of the quadratic differential operators at issue are evaluated by
means of the Gelfang-Yaglom method. In doing so the explicit computation of the
conventional ratio of determinants takes as reference the harmonic oscillator
whose frequency is the average of the individual frequencies derived from the
non-equivalent minima of the potential. Eventually the physical effects of the
multi-instanton configurations are included in this approach. As a matter of
fact we obtain information about the energies of the ground-state and the two
first excited levels of the discrete spectrum at issue.Comment: 12 pages, RevTe
Gravitino and Axino SuperWIMPs
Gravitinos and axinos produced in the late decays of other supersymmetric
particles are well-motivated dark matter (DM) candidates, whose experimental
evidences are very distinctive and different from other standard candidates, as
thermal produced neutralinos in similar supersymmetric models. In particular,
charged sleptons could appear stable because of the length of its lifetime. The
direct production of such particles at both the Large Hadron Collider (LHC) and
a future International Linear Collider (ILC) can give not only a clear
signature of supersymmetry but also the first non-gravitational evidence of
dark matter.Comment: 4 pages, LaTeX, 1 figure, Updated references. To appear in
Proceedings of SUSY06, the 14th International Conference on Supersymmetry and
the Unification of Fundamental Interactions, UC Irvine, California, 12-17
June 200
- …