156 research outputs found
Positive mass theorem in extended supergravities
Following the Witten-Nester formalism, we present a useful prescription using
Weyl spinors towards the positivity of mass. As a generalization of
arXiv:1310.1663, we show that some "positivity conditions" must be imposed upon
the gauge connections appearing in the supercovariant derivative acting on
spinors. A complete classification of the connection fulfilling the positivity
conditions is given. It turns out that these positivity conditions are indeed
satisfied for a number of extended supergravity theories. It is shown that the
positivity property holds for the Einstein-complex scalar system, provided that
the target space is Hodge-Kahler and the potential is expressed in terms of the
superpotential. In the Einstein-Maxwell-dilaton theory with a dilaton
potential, the dilaton coupling function and the superpotential are fixed by
the positive mass property. We also explore the gauged supergravity and
demonstrate that the positivity of the mass holds independently of the gaugings
and the deformation parameters.Comment: v2: 22 pages, typos fixed and refs added, a section discussing the
Einstein-Maxwell-dilaton theory added, an appendix classifies the connection
satisfying positivity conditions, accepted for publication in NP
Positive energy theorem implies constraints on static steller models
Using the positive energy theorem, we derive some constraints on static
steller models in asymptotically flat spacetimes in a general setting without
imposing spherical symmetry. We show that there exist no regular solutions
under certain conditions on the equation of state. As the contraposition, we
obtain some constraints on the pressure and adiabatic index.Comment: 7 pages, final version accepted for publication in Prog. Theore. Phy
Quantum Decoherence of Subcritical Bubble in Electroweak Phase Transition
In a weakly first order phase transition the typical scale of a subcritical
bubble calculated in our previous papers turned out to be too small. At this
scale quantum fluctuations may dominate and our previous classical result may
be altered. So we examine the critical size of a subcritical bubble where
quantum-to-classical transition occurs through quantum decoherence. We show
that this critical size is almost equal to the typical scale which we
previously obtained.Comment: 9 pages, LaTex file, to appear in Progress of Theoretical Physic
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