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Title: Minimal four-family supergravity model

Abstract

We investigate minimal four-family MSSM supergravity theories containing an additional general ({ital t}{prime},{ital b}{prime},{tau}{prime},{nu}{prime}) of heavy fermions along with their superpartners. We constrain the models by demanding gauge coupling constant unification at high energy scales, perturbative values for all Yukawa couplings for energy scales up to the grand-unification scale, radiative electroweak (EW) symmetry breaking via renormalization group evolution down from the grand-unification scale, a neutral LSP, and consistency with constraints from direct searches for new particles and precision electroweak data. The perturbative constraints imply a rather light fourth-family quark and lepton spectrum, and tan {beta}{approx_lt}3. The lightest {ital CP}-even Higgs boson mass receives fourth-family loop corrections that can result in as much as a 30% increase over the corresponding three-family mass value. Significant fourth-family Yukawa coupling contributions to the evolution of scalar masses lead to unexpected mass hierarchies among the sparticles. The {tilde {tau}} {sub 1}{sup {prime}} is generally the lightest slepton and the lightest squark is the {tilde {ital b}} {sub 1}{sup {prime}}. A significant lower bound is placed on the gluino mass by the simple requirement that the {tilde {tau}} {sub 1}{sup {prime}} not be the LSP. Sleptons of the first two families are much more massive comparedmore » to the LSP and other neutralinos and charginos than in the three-family models; in particular, all sleptons belonging to the first three families could easily lie beyond the reach of a {radical}{ital s} =500 GeV {ital e}{sup +}{ital e}{sup {minus}} collider. Consistency tests of the RG equations via mass sum rules and relations are explored. Relations between slepton masses and gaugino masses are shown to be very sensitive to the presence of a fourth generation. The most important near-future experimental probes of the four-family models are reviewed.« less

Authors:
 [1];  [2];  [1]
  1. Davis Institute for High Energy Physics, Department of Physics, U.C. Davis, Davis, California 95616 (United States)
  2. University of Kansas, Department of Physics and Astronomy, Lawrence, Kansas 66045 (United States)
Publication Date:
Research Org.:
University of California
OSTI Identifier:
282787
DOE Contract Number:  
FG03-91ER40674; FG02-85ER40214
Resource Type:
Journal Article
Journal Name:
Physical Review, D
Additional Journal Information:
Journal Volume: 53; Journal Issue: 3; Other Information: PBD: Feb 1996
Country of Publication:
United States
Language:
English
Subject:
66 PHYSICS; SUPERGRAVITY; FERMIONS; SPARTICLES; COUPLING CONSTANTS; YUKAWA POTENTIAL; QUARKS; LEPTONS; HIGGS BOSONS; CORRECTIONS; SPECTRA; RENORMALIZATION GROUP METHOD

Citation Formats

Gunion, J F, McKay, D W, and Pois, H. Minimal four-family supergravity model. United States: N. p., 1996. Web. doi:10.1103/PhysRevD.53.1616.
Gunion, J F, McKay, D W, & Pois, H. Minimal four-family supergravity model. United States. https://doi.org/10.1103/PhysRevD.53.1616
Gunion, J F, McKay, D W, and Pois, H. Thu . "Minimal four-family supergravity model". United States. https://doi.org/10.1103/PhysRevD.53.1616.
@article{osti_282787,
title = {Minimal four-family supergravity model},
author = {Gunion, J F and McKay, D W and Pois, H},
abstractNote = {We investigate minimal four-family MSSM supergravity theories containing an additional general ({ital t}{prime},{ital b}{prime},{tau}{prime},{nu}{prime}) of heavy fermions along with their superpartners. We constrain the models by demanding gauge coupling constant unification at high energy scales, perturbative values for all Yukawa couplings for energy scales up to the grand-unification scale, radiative electroweak (EW) symmetry breaking via renormalization group evolution down from the grand-unification scale, a neutral LSP, and consistency with constraints from direct searches for new particles and precision electroweak data. The perturbative constraints imply a rather light fourth-family quark and lepton spectrum, and tan {beta}{approx_lt}3. The lightest {ital CP}-even Higgs boson mass receives fourth-family loop corrections that can result in as much as a 30% increase over the corresponding three-family mass value. Significant fourth-family Yukawa coupling contributions to the evolution of scalar masses lead to unexpected mass hierarchies among the sparticles. The {tilde {tau}} {sub 1}{sup {prime}} is generally the lightest slepton and the lightest squark is the {tilde {ital b}} {sub 1}{sup {prime}}. A significant lower bound is placed on the gluino mass by the simple requirement that the {tilde {tau}} {sub 1}{sup {prime}} not be the LSP. Sleptons of the first two families are much more massive compared to the LSP and other neutralinos and charginos than in the three-family models; in particular, all sleptons belonging to the first three families could easily lie beyond the reach of a {radical}{ital s} =500 GeV {ital e}{sup +}{ital e}{sup {minus}} collider. Consistency tests of the RG equations via mass sum rules and relations are explored. Relations between slepton masses and gaugino masses are shown to be very sensitive to the presence of a fourth generation. The most important near-future experimental probes of the four-family models are reviewed.},
doi = {10.1103/PhysRevD.53.1616},
url = {https://www.osti.gov/biblio/282787}, journal = {Physical Review, D},
number = 3,
volume = 53,
place = {United States},
year = {1996},
month = {2}
}