Journal Club

Seminar Room

If you want to propose a paper, you can contact Supratim Das Bakshi (sdb AT ugr.es)

Friday 2nd of December, 2022

Title:Evanescent Operators in One-Loop Matching Computations

Authors:Javier Fuentes-Martín, Matthias König, Julie Pagès, Anders Eller Thomsen, Felix Wilsch
Abstract: Effective Field Theory calculations used in countless phenomenological analyses employ dimensional regularization, and at intermediate stages of computations, the operator bases extend beyond the four-dimensional ones. The extra pieces -- the evanescent operators -- can ultimately be removed with a suitable renormalization scheme, resulting in a finite shift of the physical operators. Modern Effective Field Theory matching techniques relying on the method of expansion by regions have to be extended to account for this. After illustrating the importance of these shifts in two specific examples, we compute the finite shifts required to remove all evanescent operators appearing in the one-loop matching of generic ultraviolet theories to the Standard Model Effective Field Theory and elucidate the formalism for generic Effective Field Theory calculations.
Comments: 35 pages, 4 figures, one nice Mathematica user interface with SMEFT results in the ancillary files
Subjects: High Energy Physics - Phenomenology (hep-ph)
Report number: MITP-22-091, TUM-HEP-1428/22, ZU-TH-48/22
Cite as: arXiv:2211.09144 [hep-ph]
  (or arXiv:2211.09144v1 [hep-ph] for this version)
  https://doi.org/10.48550/arXiv.2211.09144

Presented by Pablo

 

Title:Limits on massless particles

Authors: Steven Weinberg, Edward Witten
Abstract: We show that in all theories with a Lorentz-covariant energy-momentum tensor, such as all known renormalizable quantum field theories, composite as well as elementary massless particles with j > 1 are forbidden. Also, in all theories with a Lorentz-covariant conserved current, such as renormalizable theories with a symmetry that commutes with all local symmetries, there cannot exist composite or elementary particles with nonvanishing values of the corresponding charge and j > 1/2.

Paper Link

Presented by Iván