Electromagnetic Interactions in Heavy Hadron Chiral Theory

Electromagnetic interactions are incorporated into Heavy Hadron Chiral Perturbation Theory. Short and long distance magnetic moment contributions to the chiral Lagrangian are identified, and $M1$ radiative decays of heavy vector mesons and sextet baryons are studied. Using recent CLEO $D^*$ branching fraction ratio data, we fit the meson coupling to the axial vector Goldstone current and find $g_1^2 = 0.34 \pm 0.48$ for \mc = 1700 \MeV. Finally, we obtain model independent predictions for total and partial widths of charm and bottom vector mesons.Comment: 12 pages, 0 figure

Beyond the Standard Model

The standard model of particle physics is marvelously successful. However, it is obviously not a complete or final theory. I shall argue here that the structure of the standard model gives some quite concrete, compelling hints regarding what lies beyond.Comment: 20 pages, 3 figures available upon request, IAS-HEP 92/2

Chiral perturbation theory for hadrons containing a heavy quark: the sequel

Charm and bottom mesons and baryons are incorporated into a low energy chiral Lagrangian. Interactions of the heavy hadrons with light octet Goldstone bosons are studied in a framework which represents a synthesis of chiral perturbation theory and the heavy quark effective theory. The differential decay rate for the semileptonic process \LBzero \to \Sigma_c^{++} + e^- + \bar{\nu}_e + \pi^- is calculated at the zero recoil point using this hybrid formalism.Comment: 12 pages (2 figures not included

Safety's Swamp: Against The Value of Modal Stability

An account of the nature of knowledge must explain the value of knowledge. I argue that modal conditions, such as safety and sensitivity, do not confer value on a belief and so any account of knowledge that posits a modal condition as a fundamental constituent cannot vindicate widely held claims about the value of knowledge. I explain the implications of this for epistemology: We must either eschew modal conditions as a fundamental constituent of knowledge, or retain the modal conditions but concede that knowledge is not more valuable than that which falls short of knowledge. This second horn—concluding that knowledge has no distinctive value—is unappealing since it renders puzzling why so much epistemological theorising focuses on knowledge, and why knowledge seems so important

The b-τ\tau-unification in GUTs with non-chiral matter

It is shown, that the presently accepted value for b-quark mass can be obtained from the requirement of the exact b-$\tau$ unification in the both non-SUSY and SUSY non-chiral extended GUTs.Comment: 10 pages, LaTeX, 4 LaTeX figures include

Introducing the Little Higgs

Little Higgs theories are an exciting new possibility for physics at TeV energies. In the Standard Model the Higgs mass suffers from an instability under radiative corrections. This ``hierarchy problem'' motivates much of current physics beyond the Standard Model research. Little Higgs theories offer a new and very promising solution to this problem in which the Higgs is naturally light as a result of non-linearly realized symmetries. This article reviews some of the underlying ideas and gives a pedagogical introduction to the Little Higgs. The examples provided are taken from the paper "A Little Higgs from a Simple Group", by D.E. Kaplan and M. Schmaltz.Comment: 10 pages, 10 figs, Plenary talk "Physics Beyond the Standard Model (Theory)" at The 31st International Conference on High Energy Physics, Amsterdam, The Netherlands, July 24--31, 200

Lepton-number violation and right-handed neutrinos in Higgs-less effective theories

Following previous work, we identify a symmetry S_nat that generalizes the concept of custodial symmetry, keeping under control deviations from the Standard Model (SM). To realize S_nat linearly, the space of gauge fields has to be extended. Covariant constraints formulated in terms of spurions reduce S_nat back to SU(2)_L x U(1)_Y. This allows for a covariant introduction of explicit S_nat-breaking parameters. We assume that S_nat is at play in a theory of electroweak symmetry-breaking without a light Higgs particle. We describe some consequences of this assumption, using a non-decoupling effective theory in which the loop expansion procedure is based on both momentum and spurion power counting, as in Chiral Perturbation Theory. A hierarchy of lepton-number violating effects follows. Leading corrections to the SM are non-oblique. The effective theory includes stable light right-handed neutrinos, with an unbroken Z_2 symmetry forbidding neutrino Dirac masses. nu_R contribution to dark matter places bounds on their masses.Comment: Corresponds to published version: added subsection VI-D about order-of-magnitude estimate