Soft Collinear Effective Theory

In this talk I review soft collinear effective theory. After a discussion of the formalism and properties of the effective field theory, I turn to phenomenology. I present results on color-suppressed B to D decays, and on the Upsilon radiative decay spectrum.Comment: 6 Pages, 3 figures. Parallel session overview talk presented at PANIC05, Particles and Nuclei International Conference, Santa Fe, NM - October 24-28, 200

Production & Decay of Quarkonium

In this talk I review NRQCD predictions for the production of charmonium at the Tevatron. After a quick presentation of the NRQCD factorization formalism for production and decay I review some old results and discuss how they compare to recent data. Following this I discuss some recent work done with Adam Leibovich and Ira Rothstein.Comment: Invited talk: 9th International Symposium on Heavy Flavor Physic

The Resummed Photon Spectrum in Radiative Upsilon Decays (And More)

In this talk I present the results of two calculations that make use of Non-Relativistic QCD and the newly developed Soft-Collinear Effective Theory. The first process considered is inclusive radiative $\Upsilon$ decay. The second process considered is the leading color-octet contribution to $e^+ e^- \to J/\psi + X$.Comment: Presented at the Conference on the Intersections of Particle and Nuclear Physics, May 19-24, 2003. Requires aippro

The role of Glauber Exchange in Soft Collinear Effective Theory and the Balitsky-Fadin-Kuraev-Lipatov Equation

In soft collinear effective theory (SCET) the interaction between high energy quarks moving in opposite directions involving momentum transfer much smaller than the center-of-mass energy is described by the Glauber interaction operator which has two-dimensional Coulomb-like behavior. Here, we determine this $n$-$\bar{n}$ collinear Glauber interaction operator and consider its renormalization properties at one loop. At this order a rapidity divergence appears which gives rise to an infrared divergent (IR) rapidity anomalous dimension commonly called the gluon Regge trajectory. We then go on to consider the forward quark scattering cross section in SCET. The emission of real soft gluons from the Glauber interaction gives rise to the Lipatov vertex. Squaring and adding the real and virtual amplitudes results in a cancelation of IR divergences, however the rapidity divergence remains. We introduce a rapidity counterterm to cancel the rapidity divergence, and derive a rapidity renormalization group equation which is the Balitsky-Fadin-Kuraev-Lipatov Equation. This connects Glauber interactions with the emergence of Regge behavior in SCET.Comment: 11 pages, 4 figure

The decay of the X(3872) into \chi_{cJ} and the Operator Product Expansion in XEFT

XEFT is a low energy effective theory for the X(3872) that can be used to systematically analyze the decay and production of the X(3872) meson, assuming that it is a weakly bound state of charmed mesons. In a previous paper, we calculated the decays of X(3872) into \chi_{cJ} plus pions using a two-step procedure in which Heavy Hadron Chiral Perturbation Theory (HH\chiPT) amplitudes are matched onto XEFT operators and then X(3872) decay rates are then calculated using these operators. The procedure leads to IR divergences in the three-body decay X(3872) \to \chi_{cJ} \pi \pi when virtual D mesons can go on-shell in tree level HH\chiPT diagrams. In previous work, we regulated these IR divergences with the $D^{*0}$ width. In this work, we carefully analyze X(3872) \to \chi_{cJ} \pi^0 and X(3872) \to \chi_{cJ} \pi \pi using the operator product expansion (OPE) in XEFT. Forward scattering amplitudes in HH\chiPT are matched onto local operators in XEFT, the imaginary parts of which are responsible for the decay of the X(3872). Here we show that the IR divergences are regulated by the binding momentum of the X(3872) rather than the width of the D^{*0} meson. In the OPE, these IR divergences cancel in the calculation of the matching coefficients so the correct predictions for the X(3872) \to \chi_{c1} \pi \pi do not receive enhancements due to the width of the D^{*0}. We give updated predictions for the decay X(3872) \to \chi_{c1} \pi \pi at leading order in XEFT.Comment: 20 pages, 10 figure

Can light Goldstone boson loops counter the `S-argument' against Technicolor?

We examine the oblique correction phenomenology of one-family Technicolor with light pseudo-Goldstone bosons. From loop calculations based on a gauged chiral lagrangian for Technicolor, we are lead to conclude that even though loops with light Goldstone bosons give a negative contribution to $S$ measured at the $Z$-pole, this effect is not sufficiently large to unambiguously counter the `S-argument' against one-family Technicolor. This result cannot be guessed \apriori, but must be explicitly calculated. Our analysis entails an extended version of the $STU$ oblique parametrization of Peskin and Takeuchi. In principle, this extended formalism ($STUVWX$) must be used when there are light new particles in loops.Comment: We have considerably shortened this paper. The bulk of the derivation of the $STUVWX$ formalism has been removed and will be presented elsewhere. More emphasis has been placed on the calculation of $STUVWX$ in a one-family Technicolor model with light psuedo-goldstone bosons. Though the result remains the same, the `S-argument' can not be countered, we have elucidated some interesting points in the calculation. In particular we emphasize the fact that it is not possible to tell from the outset what the calculated value of $S$ at the $Z$-pole will b