1,452,394 research outputs found
Non-linear Realisation of the N=2, D=6 Supergravity
We have applied the method of dualisation to construct the coset realisation
of the bosonic sector of the N=2, D=6 supergravity which is coupled to a tensor
multiplet. The bosonic field equations are regained through the Cartan-Maurer
equation which the Cartan form satisfies. The first-order formulation of the
theory is also obtained as a twisted self-duality condition within the
non-linear coset construction.Comment: 11 page
Bound States in n Dimensions (Especially n = 1 and n = 2)
We stress that in contradiction with what happens in space dimensions , there is no strict bound on the number of bound states with the same
structure as the semi-classical estimate for large coupling constant and give,
in two dimensions, examples of weak potentials with one or infinitely many
bound states. We derive bounds for one and two dimensions which have the
"right" coupling constant behaviour for large coupling.Comment: Talk given by A. Martin at Les Houches, October 2001, to appear in
"Few-Body Problems
Lepton flavor violating Higgs boson decays in seesaw models: new discussions
The lepton flavor violating decay of the Standard Model-like Higgs boson
(LFVHD), h->\mu\tau, is discussed in seesaw models at the one-loop level. Based
on particular analytic expressions of Passarino-Veltman functions, the two
unitary and 't Hooft Feynman gauges are used to compute the branching ratio of
LFVHD and compare with results reported recently. In the minimal seesaw (MSS)
model, the branching ratio was investigated in the whole valid range
10^{-9}-10^{15} GeV of new neutrino mass scale m_{n_6}. Using the Casas-Ibarra
parameterization, this branching ratio enhances with large and increasing
m_{n_6}. But the maximal value can reach only order of 10^{-11}. Interesting
relations of LFVHD predicted by the MSS and inverse seesaw (ISS) model are
discussed. The ratio between two LFVHD branching ratios predicted by the ISS
and MSS is simply m^2_{n_6}\mu^{-2}_X, where \mu_X is the small neutrino mass
scale in the ISS. The consistence between different calculations is shown
precisely from analytical approach.Comment: 4 figures, 26 pages, some analytic formulas and statements are
corrected. Main results are unchanged. New references added. Version
published in NP
Low temperature vortex liquid states induced by quantum fluctuations in the quasi two dimensional organic superconductor kappa-(BEDT-TTF)_{2} Cu(NCS)_{2}
We report the transport properties in the vortex liquid states induced by
quantum fluctuations at low temperature in the layered organic superconductor
kappa-(BEDT-TTF)_{2} Cu(NCS)_{2}. A steep drop of the resistivity observed
below about 1 K separates the liquid state into two regions. In the low
resistance state at lower temperature, a finite resistivity with weak
temperature dependence persists down to 100 mK at least. The finite resistivity
in the vortex state at T ~= 0 K indicates the realization of quantum vortex
liquid assisted by the strong quantum fluctuations instead of the thermal one.
A possible origin for separating these liquid states is a remnant vortex
melting line at the original position, which is obscured and suppressed by the
quantum fluctuations. A non-linear behavior of the in-plane resistivity appears
at large current density in only the low resistance state, but not in another
vortex liquid state at higher temperature, where the thermal fluctuations are
dominant. The transport properties in the low resistance state are well
understood in the vortex slush concept with a short-range order of vortices.
Thus the low resistance state below 1 K is considered to be a novel quantum
vortex slush state.Comment: 7 pages, 5 figure
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