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Title: Less space for a new family of fermions

Abstract

We investigate the experimentally allowed parameter space of an extension of the standard model (SM3) by one additional family of fermions. Therefore we extend our previous study of the Cabibbo-Kobayashi-Maskawa (CKM)-like mixing constraints of a fourth generation of quarks. In addition to the bounds from tree-level determinations of the 3x3 CKM elements and flavor-changing neutral currents processes (K, D, B{sub d}, B{sub s} mixing and the decay b{yields}s{gamma}) we also investigate the electroweak S, T, U parameters, the angle {gamma} of the unitarity triangle, and the rare decay B{sub s}{yields}{mu}{sup +}{mu}{sup -}. Moreover we improve our treatment of the QCD corrections compared to our previous analysis. We also take leptonic contributions into account, but we neglect the mixing among leptons. As a result we find that typically small mixing with the fourth family is favored, but still some sizeable deviations from the SM3 results are not yet excluded. The minimal possible value of V{sub tb} is 0.93. Also very large CP-violating effects in B{sub s} mixing seem to be impossible within an extension of the SM3 that consists of an additional fermion family alone. We find a delicate interplay of electroweak and flavor observables, which strongly suggests that a separatemore » treatment of the two sectors is not feasible. In particular we show that the inclusion of the full CKM dependence of the S and T parameters in principle allows the existence of a degenerate fourth generation of quarks.« less

Authors:
 [1];  [1];  [2]
  1. Institut fuer Theoretische Physik, Universitaet Regensburg, D-93040 Regensburg (Germany)
  2. Institut fuer Theoretische Teilchenphysik und Kosmologie, RWTH Aachen University, D-52056 Aachen (Germany)
Publication Date:
OSTI Identifier:
21503822
Resource Type:
Journal Article
Journal Name:
Physical Review. D, Particles Fields
Additional Journal Information:
Journal Volume: 82; Journal Issue: 9; Other Information: DOI: 10.1103/PhysRevD.82.095006; (c) 2010 American Institute of Physics; Journal ID: ISSN 0556-2821
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; B S MESONS; CORRECTIONS; CP INVARIANCE; FLAVOR MODEL; KOBAYASHI-MASKAWA MATRIX; MIXING; MUONS MINUS; MUONS PLUS; NEUTRAL CURRENTS; PARTICLE DECAY; QUANTUM CHROMODYNAMICS; QUARKS; STANDARD MODEL; UNITARITY; WEINBERG-SALAM GAUGE MODEL; ALGEBRAIC CURRENTS; ANTILEPTONS; ANTIMATTER; ANTIPARTICLES; BEAUTY MESONS; BEAUTY PARTICLES; BOSONS; COMPOSITE MODELS; CURRENTS; DECAY; ELEMENTARY PARTICLES; FERMIONS; FIELD THEORIES; GRAND UNIFIED THEORY; HADRONS; INVARIANCE PRINCIPLES; LEPTONS; MATHEMATICAL MODELS; MATRICES; MATTER; MESONS; MUONS; PARTICLE MODELS; PSEUDOSCALAR MESONS; QUANTUM FIELD THEORY; QUARK MODEL; STRANGE MESONS; STRANGE PARTICLES; UNIFIED GAUGE MODELS; UNIFIED-FIELD THEORIES

Citation Formats

Eberhardt, Otto, Lenz, Alexander, Institut fuer Physik, Technische Universitaet Dortmund, D-44221 Dortmund, and Rohrwild, Juergen. Less space for a new family of fermions. United States: N. p., 2010. Web. doi:10.1103/PHYSREVD.82.095006.
Eberhardt, Otto, Lenz, Alexander, Institut fuer Physik, Technische Universitaet Dortmund, D-44221 Dortmund, & Rohrwild, Juergen. Less space for a new family of fermions. United States. https://doi.org/10.1103/PHYSREVD.82.095006
Eberhardt, Otto, Lenz, Alexander, Institut fuer Physik, Technische Universitaet Dortmund, D-44221 Dortmund, and Rohrwild, Juergen. 2010. "Less space for a new family of fermions". United States. https://doi.org/10.1103/PHYSREVD.82.095006.
@article{osti_21503822,
title = {Less space for a new family of fermions},
author = {Eberhardt, Otto and Lenz, Alexander and Institut fuer Physik, Technische Universitaet Dortmund, D-44221 Dortmund and Rohrwild, Juergen},
abstractNote = {We investigate the experimentally allowed parameter space of an extension of the standard model (SM3) by one additional family of fermions. Therefore we extend our previous study of the Cabibbo-Kobayashi-Maskawa (CKM)-like mixing constraints of a fourth generation of quarks. In addition to the bounds from tree-level determinations of the 3x3 CKM elements and flavor-changing neutral currents processes (K, D, B{sub d}, B{sub s} mixing and the decay b{yields}s{gamma}) we also investigate the electroweak S, T, U parameters, the angle {gamma} of the unitarity triangle, and the rare decay B{sub s}{yields}{mu}{sup +}{mu}{sup -}. Moreover we improve our treatment of the QCD corrections compared to our previous analysis. We also take leptonic contributions into account, but we neglect the mixing among leptons. As a result we find that typically small mixing with the fourth family is favored, but still some sizeable deviations from the SM3 results are not yet excluded. The minimal possible value of V{sub tb} is 0.93. Also very large CP-violating effects in B{sub s} mixing seem to be impossible within an extension of the SM3 that consists of an additional fermion family alone. We find a delicate interplay of electroweak and flavor observables, which strongly suggests that a separate treatment of the two sectors is not feasible. In particular we show that the inclusion of the full CKM dependence of the S and T parameters in principle allows the existence of a degenerate fourth generation of quarks.},
doi = {10.1103/PHYSREVD.82.095006},
url = {https://www.osti.gov/biblio/21503822}, journal = {Physical Review. D, Particles Fields},
issn = {0556-2821},
number = 9,
volume = 82,
place = {United States},
year = {Mon Nov 01 00:00:00 EDT 2010},
month = {Mon Nov 01 00:00:00 EDT 2010}
}