skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Advantages of unity with SU(4)-color: Reflections through neutrino oscillations, baryogenesis and proton decay

Abstract

As a tribute to Abdus Salam, I recall the initiation in 1972-73 of the idea of grand unification based on the view that lepton number is the fourth color. Motivated by aesthetic demands, these attempts led to the suggestion that the existing SU (2) x U (1) symmetry be extended minimally to the quark-lepton and left-right symmetric non-Abelian gauge structure G (2,2,4) = SU (2) L x SU (2) R x SU (4)-color. This served to unify members of a family within a single L-R self-conjugate multiplet. It also explained: the quantization of electric charge, the co-existence of quarks and leptons, and that of their three basic forces $-$ weak, electromagnetic, and strong $-$ while providing the appealing possibility that nature is fundamentally left-right symmetric (parity-conserving). The minimal extension of the symmetry G (2,2,4) to a simple group is given by the attractive symmetry SO (10) that came a year later. The advantages of the core symmetry G (2,2,4), including those listed above (which are of course retained by SO (10) as well), are noted. These include the introductions of: (i) the right-handed neutrino as a compelling member of each family, (ii) (B-L) as a local symmetry, and (iii) themore » mass relation m (ν τ) Dirac = m top (M GUT). These three features, all arising due to SU(4)-color, as well as the gauge coupling uni cation scale (identi ed with the (B-L)- breaking scale), are crucially needed to understand the tiny mass-scales of the neutrino oscillations within the seesaw mechanism, and to implement successfully the mechanism of baryogenesis via leptogenesis. Implications of a well-motivated class of models based on supersymmetric SO(10) or a string-unified G(2, 2, 4) symmetry in 4D for (a) gauge coupling uni cation, (b) fermion masses and mixings, (c) neutrino osillations, (d) baryogenesis via leptogenesis, and last but not least (e) proton decay are presented. Recent works on the latter providing upper limits on proton lifetimes suggest that the potential for discovery of proton decay in the next-generation detectors would be high.« less

Authors:
 [1]
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1360752
Report Number(s):
SLAC-PUB-16937
Journal ID: ISSN 0217-751X
Grant/Contract Number:
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
International Journal of Modern Physics A
Additional Journal Information:
Journal Volume: 32; Journal Issue: 09; Journal ID: ISSN 0217-751X
Publisher:
World Scientific
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Pati, Jogesh C. Advantages of unity with SU(4)-color: Reflections through neutrino oscillations, baryogenesis and proton decay. United States: N. p., 2017. Web. doi:10.1142/S0217751X17410135.
Pati, Jogesh C. Advantages of unity with SU(4)-color: Reflections through neutrino oscillations, baryogenesis and proton decay. United States. doi:10.1142/S0217751X17410135.
Pati, Jogesh C. Fri . "Advantages of unity with SU(4)-color: Reflections through neutrino oscillations, baryogenesis and proton decay". United States. doi:10.1142/S0217751X17410135. https://www.osti.gov/servlets/purl/1360752.
@article{osti_1360752,
title = {Advantages of unity with SU(4)-color: Reflections through neutrino oscillations, baryogenesis and proton decay},
author = {Pati, Jogesh C.},
abstractNote = {As a tribute to Abdus Salam, I recall the initiation in 1972-73 of the idea of grand unification based on the view that lepton number is the fourth color. Motivated by aesthetic demands, these attempts led to the suggestion that the existing SU (2) x U (1) symmetry be extended minimally to the quark-lepton and left-right symmetric non-Abelian gauge structure G (2,2,4) = SU (2)L x SU (2)R x SU (4)-color. This served to unify members of a family within a single L-R self-conjugate multiplet. It also explained: the quantization of electric charge, the co-existence of quarks and leptons, and that of their three basic forces $-$ weak, electromagnetic, and strong $-$ while providing the appealing possibility that nature is fundamentally left-right symmetric (parity-conserving). The minimal extension of the symmetry G (2,2,4) to a simple group is given by the attractive symmetry SO (10) that came a year later. The advantages of the core symmetry G (2,2,4), including those listed above (which are of course retained by SO (10) as well), are noted. These include the introductions of: (i) the right-handed neutrino as a compelling member of each family, (ii) (B-L) as a local symmetry, and (iii) the mass relation m (ντ) Dirac = mtop (MGUT). These three features, all arising due to SU(4)-color, as well as the gauge coupling uni cation scale (identi ed with the (B-L)- breaking scale), are crucially needed to understand the tiny mass-scales of the neutrino oscillations within the seesaw mechanism, and to implement successfully the mechanism of baryogenesis via leptogenesis. Implications of a well-motivated class of models based on supersymmetric SO(10) or a string-unified G(2, 2, 4) symmetry in 4D for (a) gauge coupling uni cation, (b) fermion masses and mixings, (c) neutrino osillations, (d) baryogenesis via leptogenesis, and last but not least (e) proton decay are presented. Recent works on the latter providing upper limits on proton lifetimes suggest that the potential for discovery of proton decay in the next-generation detectors would be high.},
doi = {10.1142/S0217751X17410135},
journal = {International Journal of Modern Physics A},
number = 09,
volume = 32,
place = {United States},
year = {Fri Mar 24 00:00:00 EDT 2017},
month = {Fri Mar 24 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 1work
Citation information provided by
Web of Science

Save / Share:
  • A detailed study of the Higgs potential and the Higgs-fermion Yukawa couplings in the SU(3) x SU(3) x SU(3) trinification model proposed by de Rujula, Georgi, and Glashow is carried out. Spontaneous symmetry breakdown to SU(3) x SU(2) x U(1) is analyzed, stability of the ground-state vacuum assured, and the Higgs- and gauge-boson mass matrices exhibited. The most economical method of generating all fermion masses and mixings is given. The large corrections to the masses of the neutral leptons are worked out at the one- and two-loop levels and shown to be stable. The new neutral leptons (neutrettos) turn outmore » to be rather heavy (approx.100 TeV). The mass hierarchy of the neutrinos is ..nu../sub tau/>..nu../sub ..mu../>..nu../sub e/. $nu sub tau: can be a few keV, ..nu../sub ..mu../ a few eV, and ..nu../sub e/approx.10/sup -4/ eV. The ..nu../sub e/-..nu../sub ..mu../ mixing angle is about 10/sup -2/. The dominant proton-decay modes are p..-->..K/sup +/nu-bar/sub ..mu../ and p..--> pi../sup 0/..mu../sup +/ with possibly comparable rates. Other modes are suppressed. For example, GAMMA(p..--> pi../sup +/nu-bar/sub ..mu../)/ GAMMA(p..-->..K/sup +/nu-bar/sub ..mu../)approx.10/sup -2/, GAMMA(p..-->..e/sup +/..pi../sup 0/)/GAMMA(p..--> mu../sup +/..pi../sup 0/ )approx.(1/14), and p..-->..K/sup 0/..mu../sup +/ is absent.« less
  • An interesting three-lepton decay mode of the proton is analyzed in a fractionally-charged-quark SU(4)/sub c/ x SU(2)/sub L/ x SU(2) /sub R/ Pati-Salam-type model. With a quark-lepton-unification mass of about 10/sup 5/ GeV and reasonable values for the colored-Higgs-boson masses, the lifetime of the proton turns out to be of the order of 10/sup 31/ yr. This, being comparable with the results of the lifetime calculation for other decay modes, should not be ignored in the dedicated experiments.
  • We derive analytic formulas for mass scales and the GUT coupling constant in SO(10) with SU(2)[sub [ital L]][times]U(1)[sub [ital R]][times]SU(4)[sub [ital C]] ([equivalent to][ital G][sub 214]) intermediate breaking including two-loops and threshold effects. We find that the mass-scale predictions are in agreement with the CERN LEP data and proton-lifetime limit provided threshold effects due to heavy Higgs scalars are included. In one case the predicted proton lifetime is close to the experimental limit, while the [nu][sub [ital e]] mass is small, the [nu][sub [mu]] mass is accessible to laboratory experiments, and the [nu][sub [tau]] mass is consistent with the 17more » keV neutrino. In the most interesting case the predicted proton lifetime is accessible to the Superkamiokande experiments and the [nu][sub [ital e]] and [nu][sub [mu]] masses have the right values needed for understanding the solar neutrino problem using the Mikheyev-Smirnov-Wolfenstein mechanism. The [nu][sub [tau]] mass is found to be consistent with the requirement for the dark matter of the Universe.« less
  • A gauged U(1)B-L symmetry predicts three right handed handed neutrinos and its spontaneous breaking automatically yields the seesaw mechanism. In a supersymmetric setting this breaking can be nicely linked with inflation to yield {delta}T/T proportional to (MB-L/MP)2, where MB-L (MP) denote the B - L breaking (Planck) scale respectively. Thus MB-L is estimated to be of order 1016 GeV, and the heaviest right handed neutrino mass is of order 1014 GeV. A second right handed neutrino turns out to have a mass of order 10 - 102 Tr, where Tr (< or approx. 1010 GeV) denotes the reheat temperature. Amore » U(1) R symmetry plays an essential role in implementing inflation and leptogenesis, resolving the MSSM {mu} problem and eliminationg dimension five nucleon decay. An unbroken Z2 subgroup plays the role of matter parity. Extension to SO(10) is possible and implications for proton decay are briefly discussed.« less