2,336 research outputs found
Bounding the Tau Neutrino Magnetic Moment from Single Photon Searches at LEP
We show that single photon searches at LEP constrain the tau neutrino
magnetic moment to be less than . This bound is
competitive with low energy () single photon searches.Comment: 5 pgs. LaTeX, one reference fixed in revised version,
JHU-TIPAC-940004, UM-TH-94-1
Effective field theory approach to Casimir interactions on soft matter surfaces
We utilize an effective field theory approach to calculate Casimir
interactions between objects bound to thermally fluctuating fluid surfaces or
interfaces. This approach circumvents the complicated constraints imposed by
such objects on the functional integration measure by reverting to a point
particle representation. To capture the finite size effects, we perturb the
Hamiltonian by DH that encapsulates the particles' response to external fields.
DH is systematically expanded in a series of terms, each of which scales
homogeneously in the two power counting parameters: \lambda \equiv R/r, the
ratio of the typical object size (R) to the typical distance between them (r),
and delta=kB T/k, where k is the modulus characterizing the surface energy. The
coefficients of the terms in DH correspond to generalized polarizabilities and
thus the formalism applies to rigid as well as deformable objects.
Singularities induced by the point particle description can be dealt with using
standard renormalization techniques. We first illustrate and verify our
approach by re-deriving known pair forces between circular objects bound to
films or membranes. To demonstrate its efficiency and versatility, we then
derive a number of new results: The triplet interactions present in these
systems, a higher order correction to the film interaction, and general scaling
laws for the leading order interaction valid for objects of arbitrary shape and
internal flexibility.Comment: 4 pages, 1 figur
The Phenomenology of Inclusive Heavy-to-Light Sum Rules
By calculating the O(\alpha_s) corrections to inclusive heavy-to-light sum
rules we find model independent upper and lower bounds on form factors for B to
pi and B to rho. We use the bounds to rule out model predictions. Some models
violate the bounds only for certain ranges of sum rule input parameters
\bar{lambda} \simeq m_B-m_b and lambda_1, or for certain choices of model
parameters, while others obey or violate the bounds irrespective of the inputs.
We discuss the reliability and convergence of the bounds, point out their
utility for extracting V_{ub}, and derive from them a new form factor scaling
relation.Comment: 15 pages, 3 figures include
Non-Relativistic Gravitation: From Newton to Einstein and Back
We present an improvement to the Classical Effective Theory approach to the
non-relativistic or Post-Newtonian approximation of General Relativity. The
"potential metric field" is decomposed through a temporal Kaluza-Klein ansatz
into three NRG-fields: a scalar identified with the Newtonian potential, a
3-vector corresponding to the gravito-magnetic vector potential and a 3-tensor.
The derivation of the Einstein-Infeld-Hoffmann Lagrangian simplifies such that
each term corresponds to a single Feynman diagram providing a clear physical
interpretation. Spin interactions are dominated by the exchange of the
gravito-magnetic field. Leading correction diagrams corresponding to the 3PN
correction to the spin-spin interaction and the 2.5PN correction to the
spin-orbit interaction are presented.Comment: 10 pages, 3 figures. v2: published version. v3: Added a computation
of Einstein-Infeld-Hoffmann in higher dimensions within our improved ClEFT
which partially confirms and partially corrects a previous computation. See
notes added at end of introductio
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