4,222 research outputs found
Singularity Resolution in Gauged Supergravity and Conifold Unification
We obtain a unified picture for the conifold singularity resolution. We
propose that gauged supergravity, through a novel prescription for the
twisting, provides an appropriate framework to smooth out singularities in the
context of gravity duals of supersymmetric gauge theories.Comment: 13 pages, harvmac, one figure; v2: reference adde
Tunnelling between non-centrosymmetric superconductors with significant spin-orbit splitting studied theoretically within a two-band treatment
Tunnelling between non-centrosymmetric superconductors with significant
spin-orbit splitting is studied theoretically in a two-band treatment of the
problem. We find that the critical Josephson current may be modulated by
changing the relative angle between the vectors describing absence of inversion
symmetry on each side of the junction. The presence of two gaps also results in
multiple steps in the quasiparticle current-voltage characteristics. We argue
that both these effects may help to determine the pairing states in materials
like CePtSi, UIr and CdReO. We propose experimental tests of
these ideas, including scanning tunnelling microscopy.Comment: 5 pages, 1 figure. Minor changes. Some new references added.
Journal-ref. adde
Bogomol'nyi Bounds and Killing Spinors in d=3 Supergravity
We discuss the connection between the construction of Bogomol'nyi bounds and
equations in three dimensional gravitational theories and the existence of an
underlying local supersymmetric structure. We show that, appart from
matter self duality equations, a first order equation for the gravitational
field (whose consistency condition gives the Einstein equation) can be written
as a consequence of the local supersymmetry. Its solvability makes possible the
evasion of the no-go scenario for the construction of Killing spinors in
asymptotically conical spacetimes. In particular we show that the existence of
non-trivial supercovariantly constant spinors is guaranteed whenever field
configurations saturate the topological bound.Comment: 14 pages, latex, no figure
Signature of superconducting states in cubic crystal without inversion symmetry
The effects of absence of inversion symmetry on superconducting states are
investigated theoretically. In particular we focus on the noncentrosymmetric
compounds which have the cubic symmetry like LiPtB. An appropriate
and isotropic spin-orbital interaction is added in the Hamiltonian and it acts
like a magnetic monopole in the momentum space. The consequent pairing
wavefunction has an additional triplet component in the pseudospin space, and a
Zeeman magnetic field can induce a collinear supercurrent
with a coefficient . The effects of anisotropy embedded in the cubic
symmetry and the nodal superconducting gap function on are also
considered. From the macroscopic perspectives, the pair of mutually induced
and magnetization can affect the distribution of magnetic
field in such noncentrosymmetric superconductors, which is studied through
solving the Maxwell equation in the Meissner geometry as well as the case of a
single vortex line. In both cases, magnetic fields perpendicular to the
external ones emerge as a signature of the broken symmetry.Comment: 16 pages in pre-print forma
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