Matching QCD and HQET heavy-light currents at three loops

We consider the currents formed by a heavy and a light quark within Quantum Chromodynamics and compute the matching to Heavy Quark Effective Theory to three-loop accuracy. As an application we obtain the third-order perturbative corrections to ratios of B-meson decay constants.Comment: 23 pages, full results are available as Mathematica files at http://www-ttp.particle.uni-karlsruhe.de/Progdata/ttp09/ttp09-41/ ; v2: an error in comparison with Ref. [8] fixed ; v3: Journal versio

Light quark mass effects in the on-shell renormalization constants

We compute the three-loop relation between the pole and the minimally subtracted quark mass allowing for virtual effects from a second massive quark. We also consider the analogue effects for the on-shell wave function renormalization constant.Comment: 24 page

ABJ(M) Chiral Primary Three-Point Function at Two-loops

This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.archiveprefix: arXiv primaryclass: hep-th reportnumber: QMUL-PH-14-10 slaccitation: %%CITATION = ARXIV:1404.1117;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: QMUL-PH-14-10 slaccitation: %%CITATION = ARXIV:1404.1117;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: QMUL-PH-14-10 slaccitation: %%CITATION = ARXIV:1404.1117;%%Article funded by SCOAP

Simultaneous decoupling of bottom and charm quarks

We compute the decoupling relations for the strong coupling, the light quark masses, the gauge-fixing parameter, and the light fields in QCD with heavy charm and bottom quarks to three-loop accuracy taking into account the exact dependence on $m_c/m_b$. The application of a low-energy theorem allows the extraction of the three-loop effective Higgs-gluon coupling valid for extensions of the Standard Model with additional heavy quarks from the decoupling constant of $\alpha_s$.Comment: 30 page

The NNLO gluon fusion Higgs production cross-section with many heavy quarks

We consider extensions of the Standard Model with a number of additional heavy quarks which couple to the Higgs boson via top-like Yukawa interactions. We construct an effective theory valid for a Higgs boson mass which is lighter than twice the lightest heavy quark mass and compute the corresponding Wilson coefficient through NNLO. We present numerical results for the gluon fusion cross-section at the Tevatron for an extension of the Standard Model with a fourth generation of heavy quarks. The gluon fusion cross-section is enhanced by a factor of roughly 9 with respect to the Standard Model value. Tevatron experimental data can place stringent exclusion limits for the Higgs mass in this model.Comment: 14 pages, 1 tabl