119226921
Two-Higgs-doublet models and enhanced rates for a 125 GeV Higgs
A bstractWe examine the level of enhancement that can be achieved in the ZZ and γγ channels for a two-Higgs-doublet model Higgs boson (either the light h or the heavy H) with mass near 125 GeV after imposing all constraints from LEP data, B physics, precision electroweak data, vacuum stability, unitarity and perturbativity. The latter constraints restrict substantially the possibilities for enhancing the gg → h → γγ or gg → H → γγ signal relative to that for the SM Higgs, hSM. Further, we find that a large enhancement of the gg → h → γγ or gg → H → γγ signal in Type II models is possible only if the gg → h → ZZ or gg → H → ZZ mode is even more enhanced, a situation disfavored by current data. In contrast, in the Type I model one can achieve enhanced rates in the γγ final state for the h while having the ZZ mode at or below the SM rate — the largest [gg → h → γγ]/[gg → hSMγγ] ratio found is of order ~ 1.3 when the two Higgs doublet vacuum expectation ratio is tan β = 4 or 20 and the charged Higgs boson has its minimal LEP-allowed value of mH± = 90 GeV.
45741338
Diagnosing degenerate Higgs bosons at 125 GeV.
We develop diagnostic tools that would provide incontrovertible evidence for the presence of more than one Higgs boson near 125 GeV in the LHC data.
118596846
The constrained NMSSM and Higgs near 125 GeV
Abstract We assess the extent to which various constrained versions of the NMSSM are able to describe the recent hints of a Higgs signal at the LHC corresponding to a Higgs mass in the range 123–128 GeV.
119296553
Extending two-Higgs-doublet models by a singlet scalar field — The case for dark matter
A bstractWe extend the two-Higgs doublet models of Type I and Type II by adding a real gauge-singlet scalar S dark matter candidate (2HDMS models). We impose theoretical constraints deriving from perturbativity, stability, unitarity and correct electroweak symmetry breaking and require that the lightest CP-even Higgs, h, fit the LHC data for the ∼ 125.5 GeV state at the 68% C.L. after including existing constraints from LEP and B physics and LHC limits on the heavier Higgs bosons. We find that these models are easily consistent with the LUX and SuperCDMS limits on dark-matter-Nucleon scattering and the observed Ωh2 for S masses above about 55 GeV. At lower mS, the situation is more delicate. For points with mS in the 6-25 GeV range corresponding to the CDMS II and CRESST-II positive signal ranges, the dark-matter-Nucleon cross sections predicted by the Type I and Type II models more or less automatically fall within the 95%–99% C.L. signal region boundaries. Were it not for the LUX and SuperCDMS limits, which exclude all (almost all) such points in the case of Type I (Type II), this would be a success for the 2HDMS models. In fact, in the case of Type II there are a few points with 5.5 GeV ≲ mS ≲ 6.2 GeV that survive the LUX and SuperCDMS limits and fall within the CDMS II 99% C.L. signal region. Possibilities for dark matter to be isospin-violating in this 2HDMS context are also examined.
119275366
125 GeV Higgs bosons in two-Higgs-doublet models
Moriond 2013 ALTAS data at 125 GeV state appears to exhibit a substantial excess in the di-photon final state and in the ZZ decaying to four lepton channel, whereas which are more or less SM-like rate observed by CMS MVA analysis. We examine the maximum Higgs signal enhancements that can be achieved in the 2HDM when either a single Higgs or more than one Higgs have mass(es) near 125 GeV. In general, the constraints of vacuum stability, unitarity and perturbativity play the key role in restricting possibilities of signal enhancement. The Type II model allows for an enhancement in the di-photon rate (relative to the SM) of the order of 2-3 but associated with an even larger ZZ or too large \tau\tau signal. In contrast, the maximal value of the di-photon signal in the Type I model can reach the order of 1.3 for which the ZZ signal is of order 1.
56216722
Could two NMSSM Higgs bosons be present near 125 GeV
We examine next-to-minimal supersymmetric model scenarios with partial parameter unification at the grand unification scale in which both ${h}_{1}$ and ${h}_{2}$ lie in the 123\char21{}128 GeV mass range. Very substantially enhanced $\ensuremath{\gamma}\ensuremath{\gamma}$ and other rates are possible. Broadened mass peaks are natural.
16931224
Loop induced W+- H-+ associated production via photon-photon collisions in the THDM and the MSSM
We study the loop induced production of charged Higgs boson associated with W-boson via photon-photon collisions at linear colliders (LC). The investigation is carried out under the two-Higgs-doublet model(THDM) and the minimal supersymmetric model (MSSM) using full on-mass-shell renormalization scheme. The numerical analysis of their production rates is presented with some typical parameter sets. The results show that the total cross sections in frame of the MSSM at linear colliders(LC) can reach 0.1 femto barn quantitatively. The contributions from supersymmetric sector can lead to an order of magnitude enhancement of the cross section in some parameter space. We conclude that the associated WH production rate in photon-photon collision mode is comparable to that in ee collision mode. PACS number(s): 12.60.Jv, 12.60.Fr, 12.15.Lk, 13.85.-t The project supported by National Natural Science Foundation of China
123025416
Bc DECAYS TO HEAVY-LIGHT ORBITALLY EXCITED MESONS
We calculate the exclusive semileptonic and nonleptonic decays of Bc meson to heavy-light orbitally excited states in the framework of the improved Bethe–Salpeter method. The hadronic matrix elements are calculated and expressed as overlap integrals of the relativistic Salpeter wave functions of corresponding mesons, decay rates of the semileptonic and nonleptonic Bc decays to , and are obtained. Some channels provide us sizable ratios, for examples, and , with such ratios, the missing scalar Bs0 may be detected though its cascade strong decays in the forthcoming LHC experiment.
117382818
The Study of Rare $B_c\rightarrow D^{(*)}_{s,d}l\bar{l}$ Decays
In this paper, we study rare decays $B_c\rightarrow D^{(*)}_{s,d}l\bar{l}$ within the Standard Model. The penguin, box, annihilation, color-favored cascade and color-suppressed cascade contributions are included. Based on our calculation, the annihilation and color-favored cascade diagrams play important roles in the differential branching fractions, forward-backward asymmetries, longitudinal polarizations of the final vector mesons and leptonic longitudinal polarization asymmetries. More importantly, color-favored cascade decays largely enhance the resonance cascade contributions. To avoid the resonance cascade contribution pollution, new cutting regions are put forward.
118684924
Analytical computation of critical exponents in several holographic superconductors
It is very interesting that all holographic superconductors, such as s-wave, p-wave and d-wave holographic superconductors, show the universal mean-field critical exponent 1/2 at the critical temperature, just like Gindzburg-Landau (G-L) theory for second order phase transitions. Now it is believed that the universal critical exponents appear because the dual gravity theory is classic in the large N limit. However, even in the large N limit there is an exception called “non-mean-field theory”: an extension of the s-wave model with a cubic term of the charged scalar field shows a different critical exponent 1. In this paper, we try to use analytical methods to obtain the critical exponents for these models to see how the properties of the gravity action decides the appearance of the mean-field behaviors. It will be seen that just like the G-L theory, it is the fundamental symmetries rather than the detailed parameters of the bulk theory that lead to the universal properties of the holographic superconducting phase transition. The feasibility of the called “non-mean-field theory” is also discussed.
121754937
A MODEL STUDY OF QUARK NUMBER SUSCEPTIBILITY AT FINITE CHEMICAL POTENTIAL AND ZERO TEMPERATURE
In this paper, we try to provide a direct method for calculating quark number susceptibility at finite chemical potential and zero temperature. In our approach, quark number susceptibility is totally determined by G[mu](p) (the dressed quark propagator at finite chemical potential mu). By applying the general result given in Phys. Rev. C 71, 015205 (2005), G[mu](p) is calculated from the model quark propagator proposed in Phys. Rev. D 67, 054019 (2003). From this the full analytic expression of quark number susceptibility at finite mu and zero T is obtained.