16,092 research outputs found
Recommended from our members
Unearthing Ethnocentrism in Music Research: Latin American Experiences with Ethnomusicology
Latin American Studie
Chiral fermions and gauge-fixing in five-dimensional theories
We study in detail the issue of gauge-fixing in theories with one universal
extra dimension, i.e. theories where both bosons and fermions display
Kaluza-Klein (KK) excitations. The extra dimension is compactified using the
standard orbifold construction for a massless chiral fermion. We carry out the
gauge-fixing procedure at the level of the five-dimensional theory and
determine the tree-level propagators and interaction vertices needed for
performing perturbative calculations with the effective four-dimensional theory
resulting after the compactification. The gauge-independence of the tree-level
S-matrix involving massive KK modes is verified using specific examples. In
order to obtain massive fermionic zero modes one has to enlarge the theory by
introducing a set of mirror fermions, a construction which is carried out in
detail. Finally, the gauge-independence of the tree-level S-matrix involving
the resulting new mass-eigenstates is proved by resorting to generalized
current conservation equations.Comment: 10 pages, 5 figures, revtex and axodra
"Secret" neutrino interactions
We review the information about a potentially strong non-standard
four-neutrino interaction that can be obtained from available experimental
data. By using LEP results and nucleosynthesis data we find that a contact
four-fermion neutrino interaction that involve only left-handed neutrinos or
both left-handed and right-handed neutrinos cannot be stronger than the
standard weak interactions. A much stronger interaction involving only
right-handed neutrinos is still allowed.Comment: 12 pages, 2 figures, latex with ws-p8-50x6-00.cls, Talk presented in
"Neutrino Mixing", in honour of Samoil Bilenky's 70th Birthday, Torino, March
199
An Experimental Study on the Effect of Water on Historic Brickwork Masonry
Architectural heritage is deeply threatened by extreme weather events due to ongoing climatic change. Since these phenomena are becoming more and more serious, their effects cannot be neglected when a reliable assessment of a historic masonry structure is required. In this paper, the phenomenon of rising damp was studied, focusing on the influence of water on the unit weight of masonry walls made from fired clay bricks and lime mortar. This study consists of a basic experimental research on the variations in the unit weight of masonry undergoing an ageing treatment, which was simulated through some cycles of capillary water absorption and temperature changes. The experimental study proves that penetrating damp causes an increase in masonry unit weight of more than 20%. This basic result is significant in the structural assessment of historic masonry buildings. Subsequent papers will analyze the interaction with strengths parameters
- …