3,120 research outputs found
Massive Higher Spin Fields Coupled to a Scalar: Aspects of Interaction and Causality
We consider in detail the most general cubic Lagrangian which describes an
interaction between two identical higher spin fieldsin a triplet formulation
with a scalar field, all fields having the same values of the mass. After
performing the gauge fixing procedure we find that for the case of massive
fields the gauge invariance does not guarantee the preservation of the correct
number of propagating physical degrees of freedom. In order to get the correct
number of degrees of freedom for the massive higher spin field one should
impose some additional conditions on parameters of the vertex. Further
independent constraints are provided by the causality analysis, indicating that
the requirement of causality should be imposed in addition to the requirement
of gauge invariance in order to have a consistent propagation of massive higher
spin fields.Comment: 34 pages, comments, references and one Appendix added. Typos
corrected. Published versio
Current Exchanges for Reducible Higher Spin Modes on AdS
We show how to decompose a Lagrangian for reducible massless bosonic Higher Spin modes into the ones describing irreducible (Fronsdal) Higher Spin modes on a D dimensional AdS space. Using this decomposition we construct a new nonabelian cubic interaction vertex for reducible higher spin modes and two scalars on AdS from the already known vertex which involves irreducible (Fronsdal) mode
The degenerate gravitino scenario
In this work, we explore the "degenerate gravitino" scenario where the mass
difference between the gravitino and the lightest MSSM particle is much smaller
than the gravitino mass itself. In this case, the energy released in the decay
of the next to lightest sypersymmetric particle (NLSP) is reduced. Consequently
the cosmological and astrophysical constraints on the gravitino abundance, and
hence on the reheating temperature, become softer than in the usual case. On
the other hand, such small mass splittings generically imply a much longer
lifetime for the NLSP. We find that, in the constrained MSSM (CMSSM), for
neutralino LSP or NLSP, reheating temperatures compatible with thermal
leptogenesis are reached for small splittings of order 10^{-2} GeV. While for
stau NLSP, temperatures of 4x10^9 GeV can be obtained even for splittings of
order of tens of GeVs. This "degenerate gravitino" scenario offers a possible
way out to the gravitino problem for thermal leptogenesis in supersymmetric
theories.Comment: 27 pages, 10 figures and 1 table. Minor typos and references fixed.
Matches published version in JCAP
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