Browsing by Author "Salvio, Alberto"

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    4D Effective Theory and Geometrical Approach
    (2006-10-04T10:42:39Z) Salvio, Alberto; Physics; Elementary Particle Theory
    We consider the 4D effective theory for the light Kaluza-Klein (KK) modes. The heavy KK mode contribution is generally needed to reproduce the correct physical predictions: an equivalence, between the effective theory and the D-dimensional (or geometrical) approach to spontaneous symmetry breaking (SSB), emerges only if the heavy mode contribution is taken into account. This happens even if the heavy mode masses are at the Planck scale. In particular, we analyze a 6D Einstein-Maxwell model coupled to a charged scalar and fermions. Moreover, we briefly review non-Abelian and supersymmetric extensions of this theory.
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    Gauge Fields, Fermions and Mass Gaps in 6D Brane Worlds
    (2006-09-07T11:33:08Z) Parameswaran, Susha L.; Randjbar-Daemi, S.; Salvio, Alberto; Physics; Elementary Particle Theory
    We study fluctuations about axisymmetric warped brane solutions in 6D minimal gauged supergravity. Much of our analysis is general and could be applied to other scenarios. We focus on bulk sectors that could give rise to Standard Model gauge fields and charged matter. We reduce the dynamics to Schroedinger type equations plus physical boundary conditions, and obtain exact solutions for the Kaluza-Klein wave functions and discrete mass spectra. The power-law warping, as opposed to exponential in 5D, means that zero mode wave functions can be peaked on negative tension branes, but only at the price of localizing the whole Kaluza-Klein tower there. However, remarkably, the codimension two defects allow the Kaluza-Klein mass gap to remain finite even in the infinite volume limit. In principle, not only gravity, but Standard Model fields could `feel' the extent of large extra dimensions, and still be described by an effective 4D theory.