4,026 research outputs found

    New Formulas and Predictions for Running Masses at Higher Scales in MSSM

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    Including contributions of scale-dependent vacuum expectation values of Higgs scalars, we derive new one-loop formulas analytically for running quark-lepton masses at higher scales in MSSM. Apart from the gauge-coupling dependence being different from earlier formulas, the third-generation- Yukawa-coupling effects are absent in the masses of the first two generations. While predicting the masses and tanβ\tan\beta numerically, we also include two-loop effects.Comment: 9 pages Latex.Typos correcte

    Vanishing corrections on the intermediate scale and implications for unification of forces

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    In two-step breaking of a class of grand unified theories including SO(10),we prove a theorem showing that the scale MIM_I where the Pati-Salam gauge symmetry with parity breaks down to the standard gauge group,has vanishing corrections due to all sources emerging from higher scales μ>MI \mu >M_I such as the one-loop and all higher loop effects,the GUT-threshold,gravitational smearing,and string threshold effects. Implications of such a scale for the unification of gauge couplings with small Majorana neutrino masses are discussed.In string inspired SO(10) we show that MI5×1012M_I \simeq 5\times 10^{12},needed for neutrino masses,with the GUT scale MUMstrM_U \simeq M_{str} can be realized provided certain particle states in the predicted spectum are light.Comment: 21 pages, Late

    New Formulas and Predictions for Running Fermion Masses at Higher Scales in SM, 2HDM, and MSSM

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    Including contributions of scale-dependent vacuum expectation values, we derive new analytic formulas and obtain substantially different numerical predictions for the running masses of quarks and charged-leptons at higher scales in the SM, 2HDM and MSSM. These formulas exhibit significantly different behaviours with respect to their dependence on gauge and Yukawa couplings than those derived earlier. At one-loop level the masses of the first two generations are found to be independent of Yukawa couplings of the third generation in all the three effective theories in the small mixing limit. Analytic formulas are also obtained for running tanβ(μ)\tan\beta(\mu) in 2HDM and MSSM. Other numerical analyses include study of the third generation masses at high scales as functions of low-energy values of tanβ\tan\beta and SUSY scale MS=MZ104M_S=M_Z-10^4 GeV.Comment: 42 pages RevTeX, including 16 figures. Typos corrected and one reference adde

    Neutrino Mass, Coupling Unification, Verifiable Proton Decay, Vacuum Stability and WIMP Dark Matter in SU(5)

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    Nonsupersymmetric minimal SU(5) with Higgs representations 24H{24}_H and 5H5_H and standard fermions in 5ˉF10F{\bar 5}_F\oplus {10}_F is well known for its failure in unification of gauge couplings and lack of predicting neutrino masses. Like standard model, it is also affected by the instability of the Higgs scalar potential. We note that extending the Higgs sector by 75H{75}_H and 15H{15}_H not only leads to the popular type-II seesaw ansatz for neutrino masses with a lower bound on the triplet mass MΔ>2×109M_{\Delta} > 2\times 10^9 GeV, but also achieves precision unification of gauge couplings without proliferation of non-standard light Higgs scalars or fermions near the TeV scale. Consistent with recent LUX-2016 lower bound, the model easily accommodates a singlet scalar WIMP dark matter near the TeV scale which resolves the vacuum stability issue even after inclusion of heavy triplet threshold effect. We estimate proton lifetime predictions for pe+π0p\to e^+\pi^0 including uncertainties due to input parameters and threshold effects due to superheavy Higgs scalars and superheavy X±4/3,Y±1/3X^{\pm 4/3},Y^{\pm 1/3} gauge bosons. The predicted lifetime is noted to be verifiable at Super Kamiokande and Hyper Kamiokande experiments.Comment: 36 pages, 9 figures (Accepted for publication in Advances in High Energy Physics