Xavier Garcia i Tormo

Determination of

We compare lattice data for the short-distance part of the static energy in 2 + 1 flavor quantum chromodynamics (QCD) with perturbative calculations, up to next-to-next-to-next-to leadinglogarithmic accuracy. We show that perturbation theory describes very well the lattice data at short distances, and exploit this fact to obtain a determination of the product of the lattice scale r0 with

\alpha_s

We present an update of our determination of the strong coupling αs from the quantum chromodynamics static energy. This updated analysis includes new lattice data, at smaller lattice spacings and reaching shorter distances, the use of better suited perturbative expressions to compare with data in a wider distance range, and a comprehensive and detailed estimate of the error sources that contribute to the uncertainty of the final result. Our updated value for αs at the Z-mass scale, MZ, is αs(MZ)=0.1166+0.0012−0.0008, which supersedes our previous result.

from the QCD static energy

Experimental searches for lepton-flavor-violating coherent muon-to-electron conversion in the field of a nucleus, have been proposed to reach the unprecedented sensitivity of 10^(-16) - 10^(-18) per stopped muon. At that level, they probe new interactions at effective-mass scales well beyond 1000 TeV. However, they must contend with background from ordinary bound muon decay. To better understand the background-spectrum shape and rate, we have carried out a detailed analysis of Coulombic-bound-state muon decay, including nuclear recoil. Implications for future experiments are briefly discussed.

Determination of α s from the QCD static energy: An update

In this addendum to T. Becher and X. Garcia i Tormo, Phys. Rev. D 88, 013009 (2013), we give results for the electroweak Sudakov corrections in gauge-boson production at large transverse momentum pT at proton colliders. For the results to be easily usable, we provide a simple and accurate parametrization of the corrections as a function of pT and the center-of-mass energy s√. Additionally, we also discuss the dependence of the electroweak corrections on the rapidity of the produced boson and comment on the complications that arise in the photon-production case due to isolation requirements.

Muon decay in orbit: spectrum of high-energy electrons

We use the recently obtained theoretical expression for the complete QCD static energy at next-to-next-to-next-to leading-logarithmic accuracy to determine r₀ΛMS by comparison with available lattice data, where r₀ is the lattice scale and ΛMS is the QCD scale. We obtain r₀ΛMS=0.637(+0.032)(-0.030) [corrected] for the zero-flavor case. The procedure we describe can be directly used to obtain r₀ΛMS in the unquenched case, when unquenched lattice data for the static energy at short distances becomes available. Using the value of the strong coupling α(s) as an input, the unquenched result would provide a determination of the lattice scale r₀.

Addendum to “Electroweak Sudakov effects in W , Z and γ production at large transverse momentum”

We present factorization theorems for two exclusive heavy-quarkonium production processes: production of two quarkonia in

Precision determination of r_0Lambda_MS from the QCD static energy

{e}^{+}{e}^{\ensuremath{-}}

Factorization in exclusive quarkonium production

annihilation and production of a quarkonium and a light meson in

Electroweak Sudakov effects inW,Zandγproduction at large transverse momentum

B

Michel decay spectrum for a muon bound to a nucleus

-meson decays. We describe the general proofs of factorization and supplement them with explicit one-loop analyses, which illustrate some of the features of the soft-gluon cancellations. We find that violations of factorization are generally suppressed relative to the factorized contributions by a factor