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Limits on scalar leptoquark interactions and consequences for GUTs

  • Ilja Doršner
  • Jure Drobnak
  • Svjetlana Fajfer
  • Jernej F. Kamenik
  • Nejc Košnik
Open Access
Article

Abstract

A colored weak singlet scalar state with hypercharge 4/3 is one of the possible candidates for the explanation of the unexpectedly large forward-backward asymmetry in \( t\bar{t} \) production as measured by the CDF and DØ experiments. We investigate the role of this state in a plethora of flavor changing neutral current processes and precision observables of down-quarks and charged leptons. Our analysis includes tree- and loop-level mediated observables in the K and B systems, the charged lepton sector, as well as the \( Z \to b\bar{b} \) decay width. We perform a global fit of the relevant scalar couplings. This approach can explain the (g − 2) μ anomaly while tensions among the CP violating observables in the quark sector, most notably the nonstandard CP phase (and width difference) in the B s system cannot be fully relaxed. The results are interpreted in a class of grand unified models which allow for a light colored scalar with a mass below 1 TeV. We find that the renormalizable SU(5) scenario is not compatible with our global fit, while in the SO(10) case the viability requires the presence of both the 126- and 120-dimensional representations.

Keywords

Beyond Standard Model Rare Decays GUT Quark Masses and SM Parameters 

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© The Author(s) 2011

Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.

Authors and Affiliations

  • Ilja Doršner
    • 1
  • Jure Drobnak
    • 2
  • Svjetlana Fajfer
    • 3
    • 2
  • Jernej F. Kamenik
    • 2
    • 3
  • Nejc Košnik
    • 4
    • 2
  1. 1.Department of PhysicsUniversity of SarajevoSarajevoBosnia and Herzegovina
  2. 2.J. Stefan InstituteLjubljanaSlovenia
  3. 3.Department of PhysicsUniversity of LjubljanaLjubljanaSlovenia
  4. 4.Laboratoire de l’Accélérateur Linéaire, Centre d’OrsayUniversité de Paris-Sud XIOrsay cedexFrance

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