Abstract
Post-sphaleron baryogenesis, a fresh and profound mechanism of baryogenesis accounts for the matter-antimatter asymmetry of our present universe in a framework of Pati-Salam symmetry. We attempt here to embed this mechanism in a non-SUSY SO(10) grand unified theory by reviving a novel symmetry breaking chain with Pati-Salam symmetry as an intermediate symmetry breaking step and as well to address post-sphaleron baryogenesis and neutron-antineutron oscillation in a rational manner. The Pati-Salam symmetry based on the gauge group $SU(2)_L \times SU(2)_{R} \times SU(4)_C$ is realized in our model at $10^{5}-10^{6}$ GeV and the mixing time for the neutron-antineutron oscillation process having $\Delta B=2$ is found to be $\tau_{n-\bar{n}} \simeq 10^{8}-10^{10}\,\mbox{secs}$ with the model parameters which is within the reach of forthcoming experiments. Other novel features of the model includes low scale right-handed $W^{\pm}_R$, $Z_R$ gauge bosons, explanation for neutrino oscillation data via gauged inverse (or extended) seesaw mechanism and most importantly TeV scale color sextet scalar particles responsible for observable $n-\bar{n}$ oscillation which can be accessible to LHC. We also look after gauge coupling unification and estimation of proton life-time with and without the addition of color sextet scalars.
Highlights
A new idea behind baryon asymmetry has been explored named “PostSphaleron Baryogenesis (PSB)”, which occurs via the decay of a scalar boson singlet for the standard model having a mass around a few hundreds of GeV and a high dimensional baryon number violating coupling [8,9,10], where the Yukawa coupling(s) of the scalar(s) act as the source of the CP asymmetry
We have closely studied the mechanism of post-sphaleron baryogenesis, which can potentially explain the matter– antimatter asymmetry of the present universe, by analyzing the basic interactions using quarks and diquark Higgs
The study estimates the total baryon asymmetry to be ηB O(10−10) and neutron–antineutron oscillation with mixing time to be τn−n O(10−10–10−8) s, which may be accessible at ongoing search experiments
Summary
Inadequate knowledge of the nature of new physics beyond the standard model leaves us with no choice but to explore all possibilities which may explain the origin of the matter–antimatter asymmetry. We intend to discuss TeV scale post-sphaleron baryogenesis, the neutron–antineutron oscillation having a mixing time close to the experimental limit with the Pati–Salam symmetry or SO(10) GUT as mentioned in a recent work [19] slightly modifying the Higgs content, where nonzero light neutrino masses can be accommodated via the gauged extended inverse seesaw mechanism along with TeV scale WR, Z gauge bosons. Sub-eV masses for the light neutrinos are consistent with MD Mu (or YD Yt ) which is a generic predictions of high scale Pati–Salam symmetry and compatible with low right-handed symmetry breaking scale (MR), since the inverse seesaw formula is independent of MR We have utilized this particular property of low scale right-handed symmetry breaking in studying post-sphaleron baryogenesis and neutron–antineutron oscillation even though a complete discussion on the origin of neutrino masses and mixing via low scale extended inverse seesaw has been omitted.
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