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Baryon Number Violation beyond the Standard Model


Fornal, Bartosz (2014) Baryon Number Violation beyond the Standard Model. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/R0MY-VR06.


This thesis describes simple extensions of the standard model with new sources of baryon number violation but no proton decay. The motivation for constructing such theories comes from the shortcomings of the standard model to explain the generation of baryon asymmetry in the universe, and from the absence of experimental evidence for proton decay. However, lack of any direct evidence for baryon number violation in general puts strong bounds on the naturalness of some of those models and favors theories with suppressed baryon number violation below the TeV scale. The initial part of the thesis concentrates on investigating models containing new scalars responsible for baryon number breaking. A model with new color sextet scalars is analyzed in more detail. Apart from generating cosmological baryon number, it gives nontrivial predictions for the neutron-antineutron oscillations, the electric dipole moment of the neutron, and neutral meson mixing. The second model discussed in the thesis contains a new scalar leptoquark. Although this model predicts mainly lepton flavor violation and a nonzero electric dipole moment of the electron, it includes, in its original form, baryon number violating nonrenormalizable dimension-five operators triggering proton decay. Imposing an appropriate discrete symmetry forbids such operators. Finally, a supersymmetric model with gauged baryon and lepton numbers is proposed. It provides a natural explanation for proton stability and predicts lepton number violating processes below the supersymmetry breaking scale, which can be tested at the Large Hadron Collider. The dark matter candidate in this model carries baryon number and can be searched for in direct detection experiments as well. The thesis is completed by constructing and briefly discussing a minimal extension of the standard model with gauged baryon, lepton, and flavor symmetries.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:baryon number violation; models beyond the standard model; colored scalars; leptoquarks; supersymmetric gauge theories; dark matter
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Wise, Mark B.
Group:Caltech Theory
Thesis Committee:
  • Wise, Mark B. (chair)
  • Carroll, Sean M.
  • Politzer, Hugh David
  • Porter, Frank C.
  • Preskill, John P.
Defense Date:2 April 2014
Funding AgencyGrant Number
Henry and Grazyna A. Bauer FellowshipUNSPECIFIED
Gordon and Betty Moore Foundation776
U.S. Department of EnergyDE-FG02-92ER40701
Record Number:CaltechTHESIS:04082014-225653991
Persistent URL:
Related URLs:
URLURL TypeDescription of publications
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8184
Deposited By: Bartosz Fornal
Deposited On:28 Apr 2014 21:52
Last Modified:04 Oct 2019 00:04

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