We calculate the lowest order hadronic cross sections for producing colored heavy quark-antiquark pairs in L = S = 0 and L = S = 1 configurations. J ] long distance matrix elements which can be extracted from the data are generally consistent with NRQCD scaling rules. 4/961

Gluon fragmentation represents the dominant source of high energy prompt quarkonia at hadron colliders. Fragmentation approximations break down, however, when a quarkonium's transverse momentum becomes comparable to its mass. In this paper, we identify a large class of color-octet diagrams that mediate quarkonia production at all energies and reduce to the dominant set of gluon fragmentation graphs in the high $p_\perp$ limit. They contribute to quarkonia differential cross sections at the same order as color-singlet diagrams and bring theoretical predictions for Upsilon and Psi production at the Tevatron into agreement with experimental measurements. Using recent CDF data, we extract numerical values for bottomonia and charmonia color-octet matrix elements which are consistent with NRQCD scaling rules. We also find that quarkonia generated via the color-octet mechanism are strongly polarized at low as well as high energies. Spin alignment measurements can thus test the color-octet quarkonia production picture.Comment: 23 pages, harvmac, 11 uuencoded figure

Exclusive semileptonic B decays into excited charmed mesons are investigated at order ⌳ QCD /m Q in the heavy quark effective theory. Differential decay rates for each helicity state of the four lightest excited D mesons ͑D 1 , D 2 * , D 0 * , and D 1 *͒ are examined. At zero recoil, ⌳ QCD /m Q corrections to the matrix elements of the weak currents can be written in terms of the leading Isgur-Wise functions for the corresponding transition and meson mass splittings. A model independent prediction is found for the slope parameter of the decay rate into helicity zero D 1 at zero recoil. The differential decay rates are predicted, including ⌳ QCD /m Q corrections with some model dependence away from zero recoil and including order ␣ s corrections. Ratios of various exclusive branching ratios are computed. Matrix elements of the weak currents between B mesons and other excited charmed mesons are discussed at zero recoil to order ⌳ QCD /m Q . These amplitudes vanish at leading order, and can be written at order ⌳ QCD /m Q in terms of local matrix elements. Applications to B decay sum rules and factorization are presented. ͓S0556-2821͑98͒02901-4͔

We use the effective field theory (EFT) framework to calculate the tail effect in gravitational radiation reaction, which enters at the fourth post-Newtonian order in the dynamics of a binary system. The computation entails a subtle interplay between the near (or potential) and far (or radiation) zones. In particular, we find that the tail contribution to the effective action is nonlocal in time and features both a dissipative and a "conservative" term. The latter includes a logarithmic ultraviolet (UV) divergence, which we show cancels against an infrared (IR) singularity found in the (conservative) near zone. The origin of this behavior in the long-distance EFT is due to the point-particle limit-shrinking the binary to a pointwhich transforms a would-be infrared singularity into an ultraviolet divergence. This is a common occurrence in an EFT approach, which furthermore allows us to use renormalization group (RG) techniques to resum the resulting logarithmic contributions. We then derive the RG evolution for the binding potential and total mass/energy, and find agreement with the results obtained imposing the conservation of the (pseudo) stress-energy tensor in the radiation theory. While the calculation of the leading tail contribution to the effective action involves only one diagram, five are needed for the one-point function. This suggests logarithmic corrections may be easier to incorporate in this fashion. We conclude with a few remarks on the nature of these IR/UV singularities, the (lack of) ambiguities recently discussed in the literature, and the completeness of the analytic post-Newtonian framework.

Recent data from the CDF collaboration on the production of spin-triplet bottomonium states at the Tevatron pp collider are analyzed within the NRQCD factorization formalism. The color-singlet matrix elements are determined from electromagnetic decays and from potential models. The color-octet matrix elements are determined by fitting the CDF data on the cross sections for Υ(1S), Υ(2S), and Υ(3S) at large p T and the fractions of Υ(1S) coming from χ b (1P ) and χ b (2P ). We use the resulting matrix elements to predict the cross sections at the Tevatron for the spin-singlet states η b (nS) and h b (nP ). We argue that η b (1S) should be observable in Run II through the decay η b → J/ψ + J/ψ.