EPJ

2021 Impact factor 4.991
EPJ C - Particles and Fields
Particles and Fields
Eur. Phys. J. C 8, 301-309
DOI 10.1007/s100529901068

Probing the exotic particle content beyond the standard model

E. Ma1 - M. Raidal2 - U. Sarkar2,3

1 Department of Physics, University of California, Riverside, California 92521, USA
2 Theory Group, DESY, D-22603 Hamburg, Germany
3 Physical Research Laboratory, Ahmedabad 380 009, India

Received: 1 September 1998 / Revised version: 15 October 1998 / Published online: 22 March 1999

Abstract
We explore the possible exotic particle content beyond the standard model by examining all its scalar bilinear combinations. We categorize these exotic scalar fields and show that without the suppression of (A) their Yukawa couplings with the known quarks and leptons, and (B) the trilinear couplings among themselves, most are already constrained to be very heavy from the nonobservation of proton decay and neutron-antineutron oscillations, the smallness of $K^0 - \overline {K^0}$, $D^0 - \overline {D^0}$ and $B_d^0 - \overline {B_d^0}$ mixing, as well as the requirement of a nonzero baryon asymmetry of the universe. On the other hand, assumption (B) may be naturally violated in many models, especially in supersymmetry, hence certain exotic scalars are allowed to be below a few TeV in mass and would be easily detectable at planned future hadron colliders. In particular, large cross sections for the distinctive processes like $\bar p p \to tt,\bar t c$ and $p p \to t t, b b$ would be expected at the Fermilab Tevatron and CERN LHC, respectively.

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