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 $\nu =1$. 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 ${1 \over 2}$. 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 AdS3AdS_3 Branes and Boundary States

We examine D-branes on $AdS_3$, and find a three-brane wrapping the entire $AdS_3$, 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