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Recently, Randall and Sundrum proposed a solution to the hierarchy problem where the background spacetime is five dimensional. There are two 3-branes, and the mass scale for fields that propagate on one of the 3-branes is exponentially suppressed relative to the fundamental scale of theory, which is taken to be the Planck mass, M Pl. In this letter we show(More)
Higher order terms in the effective action of noncommutative gauge theories exhibit generalizations of the ⋆-product (e.g. ⋆ ′ and ⋆ 3). These terms do not manifestly respect the noncommutative gauge invariance of the tree level action. In U (1) gauge theories, we note that these generalized ⋆-products occur in the expansion of some quantities that are(More)
We identify a new cosmological problem for models which solve the strong CP puzzle with an invisible axion, unrelated to the domain wall problem. Because the axion is very weakly coupled, the energy density stored in the oscillations of the classical axion field does not dissipate rapidly; it exceeds the critical density needed to close the universe unless(More)
We calculate in chiral perturbation theory the dependence of Newton's gravitational constant G on the 0 parameter of quantum chromodynamics, and we find that G, as a function of 0, is minimized at 0-~ n. This calculation suggests that quantum fluctuations in the topology of spacetime would cause 0 to assume a value very near n, contrary to the(More)
Lorentz-violating operators involving Standard Model fields are tightly constrained by experimental data. The bounds are much weaker, however, on Lorentz violation appearing in purely gravitational couplings. The spontaneous breaking of Lorentz invariance by the vacuum expectation value of a vector field selects a universal rest frame. This affects the(More)
The decay constants for the D and D S mesons, denoted f D and f D S respectively, are equal in the SU (3) V limit, as are the hadronic amplitudes for B S −B S and B 0 −B 0 mixing. The leading SU (3) V violating contribution to (f D S /f D) and to the ratio of hadronic matrix elements relevant for B S − B S and B 0 − B 0 mixing amplitudes are calculated in(More)
We derive model-independent, "naturalness" upper bounds on the magnetic moments munu of Dirac neutrinos generated by physics above the scale of electroweak symmetry breaking. In the absence of fine-tuning of effective operator coefficients, we find that current information on neutrino mass implies that[EQUATION: SEE TEXT] bohr magnetons. This bound is(More)