Neutron EDM in Four Generation Standard Model

Abstract

A fourth generation of quarks, if it exist, may provide sufficient CP violation for the baryon asymmetry of the Universe. We estimate the neutron electric dipole moment in the presence of a fourth generation, and find it would be dominated by the strange quark chromoelectric dipole moment, assuming it does not get wiped out by a Peccei-Quinn symmetry. Both the three electroweak loop and the two-loop electroweak/one-loop gluonic contributions are considered. With m_{b'}, m_{t'} at 500 GeV or so that can be covered at the LHC, and with a Jarlskog CPV factor that is consistent with hints of New Physics in b to s transitions, the neutron EDM is found around 10^{-31}e cm, still far below the 10^{-28}e cm reach of the new experiments being planned or under construction.

4 pages; 5 pages, references added, comment added on hyperon EDM, note added on on t' mass and Higgs mass after EPS-HEP 2011

References in corpus (6)

• An Improved Experimental Limit on the Electric Dipole Moment of the Neutron
• Nucleon sigma term and strange quark content from lattice QCD with exact chiral symmetry
• Less space for a new family of fermions
• Large Time-dependent CP Violation in B_s^0 System and Finite D^0-D^0bar Mass Difference in Four Generation Standard Mode
• Search for heavy bottom-like quarks decaying to an electron or muon and jets in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV
• Search for a Heavy Bottom-like Quark in pp Collisions at sqrt(s) = 7 TeV