Infrared behavior of graviton-graviton scattering

The quantum effective theory of general relativity, independent of the eventual full theory at high energy, expresses graviton-graviton scattering at one loop order O(E^4) with only one parameter, Newton's constant. Dunbar and Norridge have calculated the one loop amplitude using string based techniques. We complete the calculation by showing that the 1/(d-4) divergence which remains in their result comes from the infrared sector and that the cross section is finite and model independent when the usual bremsstrahlung diagrams are included.Comment: 12 pages, uses axodra

Symmetry breaking via fermion 4-point functions

We construct the effective action and gap equations for nonperturbative fermion 4-point functions. Our results apply to situations in which fermion masses can be ignored, which is the case for theories of strong flavor interactions involving standard quarks and leptons above the electroweak scale. The structure of the gap equations is different from what a naive generalization of the 2-point case would suggest, and we find for example that gauge exchanges are insufficient to generate nonperturbative 4-point functions when the number of colors is large.Comment: 36 pages, uses Revtex and eps files for figure

New Axial Interactions at a TeV

We consider a heavy fourth family with masses lying in the symmetry breaking channel of a new strong gauge interaction. This interaction generates a heavy quark axial-type operator, whose effects can be enhanced through multiple insertions. In terms of the strength of this operator we can express new negative contributions to the S and T parameters and the shifts of the Z couplings to the third family. In particular we find that the new contribution to T is strongly constrained by the experimental constraints on the Z coupling to the tau.Comment: 14 pages, 1 figure, PRD versio

On the power counting of loop diagrams in general relativity

A class of loop diagrams in general relativity appears to have a behavior which would upset the utility of the energy expansion for quantum effects. We show through the study of specific diagrams that cancellations occur which restore the expected behaviour of the energy expansion. By considering the power counting in a physical gauge we show that the apparent bad behavior is a gauge artifact, and that the quantum loops enter with a well behaved energy expansion.Comment: 29 pages, uses axodraw and epsfig.tex, one small .eps file is included. The full PostScript version is also available as http://het.phast.umass.edu/students/kakukk/powercount_hepth.p

Dielectrophoresis of nanoscale dsDNA and humidity effects on its electrical conductivity

The dielectrophoresis method for trapping and attaching nanoscale double-stranded DNA between nanoelectrodes was developed. The method gives a high yield of trapping single or a few molecules only which enables transport measurements at the single molecule level. Electrical conductivity of individual 140-nm-long DNA molecules was measured, showing insulating behavior in dry conditions. In contrast, clear enhancement of conductivity was observed in moist conditions, relating to the interplay between the conformation of DNA molecules and their conductivity.Comment: 4 pages, 2 figure

Charmonium production at neutrino factories

At existing and planned neutrino factories (high energy and high intensity neutrino beam facilities) precision studies of QCD in neutrino-nucleon interactions are a realistic opportunity. We investigate charmonium production in fixed target neutrino experiments. We find that $J/\psi$ production in neutrino-nucleon collision is dominated by the color octet $^3S_1$ NRQCD matrix element in a neutral current process, which is not accessible in photo or leptoproduction. Neutrino experiments at a future Muon Collider will acquire sufficient event rate to accurately measure color octet matrix element contributions. The currently running high energy neutrino experiments, NOMAD and NuTeV could also observe several such events.Comment: 13 pages Latex, with five embedded eps figures. Cosmetic fixups in the figures, otherwise unchange