B.R. Kim

The absolute upper bound on the 1-loop corrected mass of the lightest scalar Higgs boson in the next-to-minimal supersymmetric standard model

We examine in detail radiative corrections to the lightest scalar Higgs boson mass due to the top quark and scalar quark loops in the next-to-minimal supersymmetric standard model (NMSSM). We take into account the nondegenerate state for the top scalar quark masses. In our analysis, the mass matrix of the top scalar quark contains the gauge terms. Therefore our formula for the scalar Higgs boson mass matrix at the 1-loop level includes the contribution of the gauge sector as well as the effect of the top scalar quark mass splitting. Thus we calculate the upper bound on the lightest scalar Higgs boson mass using our formula. We find that the absolute upper bound on the 1-loop corrected mass of the lightest scalar Higgs boson is about 156 GeV.We examine in detail radiative corrections to the lightest scalar Higgs boson mass due to the top-quark and top-scalar-quark loops in the next-to-minimal supersymmetric standard model (NMSSM). In our analysis, the mass matrix of the top-scalar-quark contains terms proportional to the gauge couplings. Therefore, our formula for the scalar Higgs boson mass matrix at the 1-loop level partially includes the gauge boson contributions. Thus we calculate the upper bound on the lightest scalar Higgs boson mass without the gauge terms as well as with the gauge terms in the top-scalar-quark masses. The upper bound on the lightest scalar Higgs boson mass can be increased by about 20 GeV by the inclusion of terms proportional to the gauge couplings in the top-scalar-quark masses. We find that the absolute upper bound on the 1-loop corrected mass of the lightest scalar Higgs boson partially including the gauge boson contributions is about 156 GeV.

Renormalization group evolution in the nonlinear supersymmetric standard model

Abstract: This work demonstrates the feasibility of in-beam γ-spectroscopy employing radioactive ion beam species at relativistic energies of E = 210 ∼ 280 A· MeV. Neutron-rich nuclei below 48Ca with neutron number between the two magic numbers 20 and 28 have been investigated. Using a Pb target, single step inelastic excitation originating mainly from Coulomb interaction takes place populating preferentially low-lying low-spin states and enabling the extraction of B(E2) values. On a C target, nucleon removal reactions are dominating and medium-spin states are populated thus offering spectroscopic information in neighboring nuclei. Cross sections of inelastic excitation are determined and compared to coupled-channels calculations. Two new states of the very neutron-rich nucleus 44Ar at 1.78(8) MeV and 2.61(16) MeV are deduced from γ-transitions.

Experimental constraints on the parameter space of the next-to-minimal supersymmetric standard model at LEP 2☆

Abstract We search for the neutral Higgs sector of the next-to-minimal supersymmetric standard model at LEP 2. At the tree level any experimental constraints on tan β cannot be set by the Higgs search at LEP 2 with s = 175 GeV , whereas at LEP 2 with s = 192 GeV tan β can be set by an experimental constraint. Furthermore the tree level parameter space of the model can be completely explored by the Higgs search at LEP 2 with s = 205GeV . Radiative corrections both to the neutral Higgs boson masses and to the relevant couplings for the scalar Higgs productions give large contributions to the production cross sections of the scalar Higgs bosons at the tree level. The tree level situation at LEP 2 with s = 192 GeV as well as with s = 205 GeV can be drastically changed by these effects. We expect that a small region of the 1-loop level parameter space of the model via the scalar Higgs production can be explored by the Higgs search at LEP 2.

Very light neutralino in nonminimal supersymmetric model

Abstract We show in the nonminimal supersymmetric model that there are parameter regions where a very light neutralino may exist without contradicting the present experimental data. We also investigate the possibility of its detection at the future 500 GeV e + e − collider.

Production of non-linear SUSY Higgs bosons at e+e− colliders

Abstract We investigate the Higgs sector of a non-linear sypersymmetric standard model at LEP 1 and LEP 2, as well as at future linear e+e− colliders with s = 500, 1000, and 2000 GeV . The LEP 1 data do not put any constraints on the parameters of the model, and allow a massless Higgs boson in particular. For LEP 2, there are remarkable differences between the Higgs productions at s = 175 GeV on the one hand and that at s = 192 GeV and 205 GeV on the other hand. The case for s = 175 GeV is similar to LEP 1, whereas those for s = 192 GeV and 205 GeV will be able to give experimental constraints on the parameters. Finally the e+e− colliders with s = 500, 1000, and 2000 GeV are most probably able to test the model conclusively.

Production of charged Higgs particles in the two-photon process at e-p scattering (HERA)

Abstract The production of charged Higgs particles via a two-photon process at the e-p collider (HERA) is calculated. We consider two cases. For Q 2 ⩽ 1 GeV 2 the process is considered quasi-elastically and the proton form factor was taken into account. For Q 2 ⩾1 GeV 2 the process is considered deep inelastically. It is shown that the production of charged Higgs particles via a two-photon process in the ep collider is the most significant one at the expected HERA and higher energy. Expected numbers of H + H − events at HERA are given.

Higgs bosons in nonlinearly realized supersymmetry

Using the formatlism developed by Samuel and Wess a general form of the Higgs potential in nonlinearly realized supersymmetric extention of the Standard Model in curved space is constructed. In flat space limit we derive bounds for Higgs boson masses and mass relations. Comparisons to the linear supersymmetric models MSSM and NMSSM are made.

Higgs bosons in the RG-improved minimal nonlinear supersymmetric SU(5) model: their mass bounds and productions at e+e− colliders

The renormalization group equations of the Higgs sector of the minimal nonlinear supersymmetric SU(5) model are derived and numerically solved in the scheme. Evolving the parameters of the model from the GUT scale down to the electroweak scale, the allowed regions of the parameters are determined, in particular the quartic coupling constant ?. The mass bounds, corrections to tree-level mass sum rules and productions of the Higgs bosons at e+e? colliders are investigated for the c.m. energy of LEP1, LEP2 and future linear colliders up to 2000 GeV.

HIGGS PARTICLE PRODUCTION AT E+E--COLLIDERS AND THE RG-IMPROVED NONLINEAR SUPERSYMMETRIC STANDARD MODEL

Abstract We consider Higgs particle production at LEP1, 2, LC-500, -1000 and -2000 with the one loop RG-improved parameters of the Nonlinear Supersymmetric Standard Model. We investigate how far this model can be tested at these colliders. Possible experimental lower bounds on mS1 are derived. We show that LC-500, -1000, -2000 will be able to test the model conclusively.

Pair production of charged Higgs particles through two-photon process inpp collisions

In order to obtain model-independent estimates for the production of charged Higgs particles atpp colliders, in particular at the SSC, we investigate their pair production through electromagnetic processes. It turns out that the dominant contribution comes from photon-photon annihilation. For a Higgs mass of a few hundred GeV the two-photon process is thus an appropriate candidate to look for charged Higgs particles.