Minimal Supersymmetric Extension Of Standard Model Research Articles

Cosmological phase transitions, gravitational waves and self-interacting dark matter in the singlet extension of MSSM

In the minimal supersymmetric standard model (MSSM) extended by a singlet superfield, when the coupling between the singlet sector and the MSSM sector is tiny, the singlet sector can be a quasi dark sector with supersymmetry (SUSY). We investigate the cosmological phenomena in this scenario and obtain the following observations: (i) In the parameter space solving the small cosmological scale anomalies via self-interacting singlino dark matter (SIDM), a first-order phase transition (FOPT) can readily happen but requires rather light dark matter below MeV; (ii) The corresponding parameter space indicated by FOPT and SIDM can be partially covered by detecting the phase-transition gravitational waves (GWs) at the near-future projects, such as LISA, TianQin and Taiji. Therefore, the recently developed GW astronomy could be a novel probe to such a SUSY scenario.

Dark matter in the singlet extension of MSSM: explanation of Pamela and implication on Higgs phenomenology

As discussed recently by Hooper and Tait, the singlino-like dark matter in the Minimal Supersymmetric Standard Model (MSSM) extended by a singlet Higgs superfield can give a perfect explanation for both the relic density and the Pamela result through the Sommerfeld-enhanced annihilation into singlet Higgs bosons (a or h followed by h → aa) with a being light enough to decay dominantly to muons or electrons. In this work we analyze the parameter space required by such a dark matter explanation and also consider the constraints from the LEP experiments. We find that although the light singlet Higgs bosons have small mixings with the Higgs doublets in the allowed parameter space, their couplings with the SM-like Higgs boson hSM (the lightest doublet-dominant Higgs boson) can be enhanced by the soft parameter Aκ and, in order to meet the stringent LEP constraints, the hSM tends to decay into the singlet Higgs pairs aa or hh instead of b. So the hSM produced at the LHC will give a multi-muon signal, hSM → aa → 4μ or hSM → hh → 4a → 8μ.

Muon g−2 and precision electroweak physics in the MSSM

The minimal supersymmetric extension of standard model (MSSM) is examined by analyzing its quantum effects on the precision electroweak measurements and the muon g−2. We examine carefully the effects of light charginos and neutralinos that are found to improve the fit to the electroweak data. We identify two distinct regions on the ( μ, M 2)-plane that fit well to the electroweak data and give significant contribution to muon g−2.

New minimal extension of MSSM

We construct a new minimal extension of the minimal supersymmetric standard model (MSSM) by promoting the μ-parameter to a singlet superfield. The resulting renormalizable superpotential is enforced by a Z 5 R-symmetry which is imposed on the non-renormalizable operators as well. The proposed model provides a natural solution to the μ-problem and is free from phenomenological and cosmological problems.

Squark loop corrections to the charged Higgs boson pair production in photon-photon collisions

We calculate the squarks one-loop corrections to the cross sections of the chared Higgs boson pair production in photon-photon collisions in the minimal supersymmetric extension of standard model(MSSM). In general, in case of the large splitting in the masses of left-top squark and the right-top squark and for $\tan\beta$ near 1.5, the corrections can reduce the cross sections by more than 10% for a wide range of the charged Higgs boson mass, depending on the $e^+e^-$ center-of-mass energy. But in other cases, the corrections are at most only a few percent. Those corrections can be comparable to the $O(\alpha m_t^2/m_W^2)$ Yukawa corrections in previous literature.

Single Minimal Supersymmetric Extension of Standard Model Higgs Production in γγ Collision

The cross sections of the single minimal supersymmetric extension of standard model(MSSM) Higgs production in γγ collision based on next linear collider with the e+e- center-of-mass energy 500 GeV have been calculated. Contributions to the cross sections arising from stops mixing are significant and have been emphasized. And the MSSM single Higgs production cross sections, which are typically in the range of 0.01 fb to several hundreds of fbs, can be comparable to that of standard model at appropriate parameters values.