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Baryon Number in Warped GUTs : Model Building and (Dark Matter Related) Phenomenology

Kaustubh Agashe, Geraldine Servant

TL;DR

The paper presents a non-supersymmetric warped GUT framework that preserves proton stability through gauged baryon number and a Z3 symmetry, predicting a light, stable KK fermion (the LZP) as a viable dark matter candidate. By embedding PS or SO(10) in RS1 and exploiting boundary-condition–driven GUT breaking, it explains Yukawa hierarchies, identifies ν′_R as the LZP, and analyzes its relic density, direct and indirect detection prospects, as well as collider signatures of other light KK partners. The work also develops an AdS/CFT interpretation, discusses gauge-coupling unification with bulk breaking, and explores broader model variants and baryogenesis connections, highlighting testable predictions at upcoming experiments. Mathematically, the framework hinges on warped-field profiles and mass scales such as M_{KK} ≈ z_v^{-1} times a factor, with LZP masses potentially in the 10 GeV–TeV range and couplings enhanced by factors of √(kπr_c) relative to SM couplings, shaping annihilation and detection cross sections via Z′, X_s, and Higgs channels.

Abstract

In the past year, a new non-supersymmetric framework for electroweak symmetry breaking (with or without Higgs) involving SU(2)_L * SU(2)_R * U(1)_{B-L} in higher dimensional warped geometry has been suggested. In this work, we embed this gauge structure into a GUT such as SO(10) or Pati-Salam. We showed recently (in hep-ph/0403143) that in a warped GUT, a stable Kaluza-Klein fermion can arise as a consequence of imposing proton stability. Here, we specify a complete realistic model where this particle is a weakly interacting right-handed neutrino, and present a detailed study of this new dark matter candidate, providing relic density and detection predictions. We discuss phenomenological aspects associated with the existence of other light (<~ TeV) KK fermions (related to the neutrino), whose lightness is a direct consequence of the top quark's heaviness. The AdS/CFT interpretation of this construction is also presented. Most of our qualitative results do not depend on the nature of the breaking of the electroweak symmetry provided that it happens near the TeV brane.

Baryon Number in Warped GUTs : Model Building and (Dark Matter Related) Phenomenology

TL;DR

The paper presents a non-supersymmetric warped GUT framework that preserves proton stability through gauged baryon number and a Z3 symmetry, predicting a light, stable KK fermion (the LZP) as a viable dark matter candidate. By embedding PS or SO(10) in RS1 and exploiting boundary-condition–driven GUT breaking, it explains Yukawa hierarchies, identifies ν′_R as the LZP, and analyzes its relic density, direct and indirect detection prospects, as well as collider signatures of other light KK partners. The work also develops an AdS/CFT interpretation, discusses gauge-coupling unification with bulk breaking, and explores broader model variants and baryogenesis connections, highlighting testable predictions at upcoming experiments. Mathematically, the framework hinges on warped-field profiles and mass scales such as M_{KK} ≈ z_v^{-1} times a factor, with LZP masses potentially in the 10 GeV–TeV range and couplings enhanced by factors of √(kπr_c) relative to SM couplings, shaping annihilation and detection cross sections via Z′, X_s, and Higgs channels.

Abstract

In the past year, a new non-supersymmetric framework for electroweak symmetry breaking (with or without Higgs) involving SU(2)_L * SU(2)_R * U(1)_{B-L} in higher dimensional warped geometry has been suggested. In this work, we embed this gauge structure into a GUT such as SO(10) or Pati-Salam. We showed recently (in hep-ph/0403143) that in a warped GUT, a stable Kaluza-Klein fermion can arise as a consequence of imposing proton stability. Here, we specify a complete realistic model where this particle is a weakly interacting right-handed neutrino, and present a detailed study of this new dark matter candidate, providing relic density and detection predictions. We discuss phenomenological aspects associated with the existence of other light (<~ TeV) KK fermions (related to the neutrino), whose lightness is a direct consequence of the top quark's heaviness. The AdS/CFT interpretation of this construction is also presented. Most of our qualitative results do not depend on the nature of the breaking of the electroweak symmetry provided that it happens near the TeV brane.

Paper Structure

This paper contains 71 sections, 137 equations, 12 figures.

Table of Contents

  1. Introduction
  2. Baryon number violation in Randall--Sundrum geometries
  3. Bulk fermion: $c$ parameter and Yukawa couplings
  4. Effective four-fermion operators
  5. Additional violations due to KK GUT gauge boson exchange
  6. Imposing baryon number symmetry $U(1)_B$
  7. Replication of fundamental representations and boundary breaking of the GUT
  8. $Z_3$ symmetry
  9. Breaking gauged baryon number symmetry
  10. Who is the lightest $Z_3$ charged particle?
  11. $(-+)$ KK fermions can be very light
  12. The LZP is likely to belong to the multiplet containing the SM right-handed top
  13. Pati-Salam model
  14. Breaking of Pati--Salam on the UV brane
  15. Bulk fermion content
  16. ...and 56 more sections

Figures (12)

  • Figure 1: Mass of the lightest ($-+$) KK fermion as a function of $c$ for different values of the KK gauge boson mass. From bottom to top, $M_{KK}=$3, 5, 7, 10 TeV.
  • Figure 2: LZP annihilation channels. $f$ denotes all SM fermions other than top and bottom.
  • Figure 3: Potentially non-negligible coannihilation channel.
  • Figure 4: The different annihilation channels evaluated at the freeze out temperature, for a typical choice of parameters, namely, $m_{KK}=3$ TeV, $c_{t_R}=-1/2$. "f" denotes all SM fermions except top and bottom.
  • Figure 5: Predictions for $\Omega_{\hbox{\tiny LZP}} \ h^2$ for two values of the gauge KK mass $M_{KK}$. Both regions are obtained by varying $g_{10}$ and $c_{\nu_L^{\prime}}$. The kink at $m_{LZP}=m_t$ corresponds to the opening of the annihilation channel into top quarks.
  • ...and 7 more figures