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Register a new userCosmological Baryon Asymmetry in Supersymmetric Standard Models and Heavy Particle Effects
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Cosmological baryon asymmetry B is studied in supersymmetric standard models, assuming the electroweak reprocessing of B and L. Only when the soft supersymmetry breaking is taken into account, B is proportional to the primordial B-L in the supersymmetric standard models. The ratio $B/(B-L)$ is found to be about one percent less than the nonsupersymmetric case. Even if the primordial B-L vanishes, scalar-leptons can be more efficient than leptons to generate B provided that mixing angles $th$ among scalar leptons satisfy $|th| < 10^{-8} (T/{GeV})^{1/2}$.
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We investigate the comparative studies of cosmological baryon asymmetry in different neutrino mass models with and without {theta}_13 by considering the three diagonal form of Dirac neutrino mass matrices, down-quark (4,2), up-quark (8,4) and charged lepton (6,2). The predictions of any models with {theta}_13 are consistent in all the three stages of leptogenesis calculations and the results are better than the predictions of any models without {theta}_13 which are consistent in a piecemeal manner with the observational data. For the best model, the normal hierarchy Type-IA for charged lepton (6,2) without {theta}_13, the predicted inflaton mass required to produce the observed baryon asymmetry is found to be 3.6x10 to the power 10 GeV corresponding to reheating temperature TR 4.5x10 to the power 6 GeV, while for the same model with {theta}_13, the inflaton mass is 2.24x10 to the power 11 GeV, TR 4.865x10 to the power 6 GeV and weak scale gravitino mass m(2 divided by 3) 100 GeV without causing the gravitino problem. These values apply to the recent discovery of Higgs boson of mass 125 GeV. The relic abundance of gravitino is proportional to the reheating temperature of the thermal bath. One can have the right order of relic dark matter abundance only if the reheating temperature is bounded to below 10 to the power 7 GeV.
We will review the main aspects of a mechanism for the contemporary generation of the baryon and Dark Matter abundances from the out-of-equilibrium decay of a Wimp-like mother particle and briefly discuss a concrete realization in a Supersymmetric scenario.
String theory has no parameter except the string scale $M_S$, so the Planck scale $M_text{Pl}$, the supersymmetry-breaking scale, the EW scale $m_text{EW}$ as well as the vacuum energy density (cosmological constant) $Lambda$ are to be determined dynamically at any local minimum solution in the string theory landscape. Here we consider a model that links the supersymmetric electroweak phenomenology (bottom up) to the string theory motivated flux compactification approach (top down). In this model, supersymmetry is broken by a combination of the racetrack Kahler uplift mechanism, which naturally allows an exponentially small positive $Lambda$ in a local minimum, and the anti-D3-brane in the KKLT scenario. In the absence of the Higgs doublets in the supersymmetric standard model, one has either a small $Lambda$ or a big enough SUSY-breaking scale, but not both. The introduction of the Higgs fields (with their soft terms) allows a small $Lambda$ and a big enough SUSY-breaking scale simultaneously. Since an exponentially small $Lambda$ is statistically preferred (as the properly normalized probability distribution $P(Lambda)$ diverges at $Lambda=0^{+}$), identifying the observed $Lambda_{rm obs}$ to the median value $Lambda_{50%}$ yields $m_{rm EW} sim 100$ GeV. We also find that the warped anti-D3-brane tension has a SUSY-breaking scale of $100m_{rm EW}$ in the landscape while the SUSY-breaking scale that directly correlates with the Higgs fields in the visible sector has a value of $m_{rm EW}$.
With the QCD sum rules approach, we study the newly discovered doubly heavy baryon $Xi_{cc}^{++}$. We analytically calculate the next-to-leading order (NLO) contribution to the perturbative part of $J^{P} = frac{1}{2}^{+}$ baryon current with two identical heavy quarks, and then reanalyze the mass of $Xi_{cc}^{++}$ at the NLO level. We find that the NLO correction significantly improves both scheme dependence and scale dependence, whereas it is hard to control these theoretical uncertainties at leading order. With the NLO contribution, the baryon mass is estimated to be $m_{Xi_{cc}^{++}} = 3.66_{-0.10}^{+0.08} text{~GeV}$, which is consistent with the LHCb measurement.
We propose a novel mechanism of electroweak symmetry breaking in supersymmetric models, as the one recently discussed by Birkedal, Chacko and Gaillard, in which the Standard Model Higgs doublet is a pseudo-Goldstone boson of some global symmetry. The Higgs mass parameter is generated at one loop level by two different, moderately fine-tuned sources of the global symmetry breaking. The mechanism works for scalar superpartner masses of order 10 TeV, but gauginos can be light. The scale at which supersymmetry breaking is mediated to the visible sector has to be low, of order 100 TeV. Fine-tuning in the scalar potential is at least two orders of magnitude smaller than in the MSSM with similar soft scalar masses. The physical Higgs boson mass is (for $tanbetagg1$) in the range 120-135 GeV.
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