Particle spectrum in the modified nonminimal supersymmetric standard model in the strong Yukawa coupling regime

A theoretical analysis of solutions of renormalization group equations in the minimal supersymmetric standard model, which lead to a quasi-fixed point has shown that the mass of the lightest Higgs boson in these models does not exceed 94 ± 5 GeV. This implies that a considerable part of the parameter space in the minimal supersymmetric model is in fact eliminated by existing LEPII experimental data. In the nonminimal supersymmetric standard model the upper bound on the mass of the lightest Higgs boson reaches its maximum in the strong Yukawa coupling regime when the Yukawa constants are substantially greater than the gauge constants on the grand unification scale. In the present paper the particle spectrum is studied using the simplest modification of the nonminimal supersymmetric standard model which gives a self-consistent solution in this region of parameter space. This model can give m _h ～ 125 GeV even for comparatively low values of β ≥ 1.9. The spectrum of Higgs bosons and neutralinos is analyzed using the method of diagonalizing mass matrices proposed earlier. In this model the mass of the lightest Higgs boson does not exceed 130.5 ± 3.5 GeV.     

Higgs bosons in the simplest SUSY models

Nowadays, in the MSSM, the moderate values of tan β are almost excluded by the LEP II lower bound on the mass of the lightest Higgs boson. In the next-to-minimal supersymmetric standard model (NMSSM), the theoretical upper bound on it increases and reaches a maximal value in the limit of strong Yukawa coupling, where all solutions to renormalization-group equations are concentrated near the quasifixed point. For a calculation of the Higgs boson spectrum, the perturbation-theory method can be applied. We investigate the particle spectrum within the modified NMSSM, which leads to the self-consistent solution in the limit of strong Yukawa coupling. This model allows one to get m _h～125 GeV at tan β≥1.9. In the model under investigation, the mass of the lightest Higgs boson does not exceed 130.5±3.5 GeV. The upper bound on the mass of the lightest CP-even Higgs boson in more complicated supersymmetric models is also discussed.     

Non-anomalous discrete R-symmetry, extra matters, and enhancement of the lightest SUSY Higgs mass

We consider low-energy supersymmetric model with non-anomalous discrete R-symmetry. To make the R-symmetry non-anomalous, we add new particles to the particle content of the minimal supersymmetric standard model (MSSM). Those new particles may couple to the Higgs boson, resulting in a significant enhancement of the lightest Higgs mass. We show that, in such a model, the lightest Higgs mass can be much larger than the MSSM upper bound; the lightest Higgs mass as large as 140 GeV (or larger) becomes possible.     

Constraints on the MSSM from the Higgs sector

We discuss the constraints on supersymmetry in the Higgs sector arising from LHC searches, rare B decays and dark matter direct detection experiments. We show that constraints derived on the mass of the lightest h ⁰ and the CP-odd A ⁰ bosons from these searches are covering a larger fraction of the SUSY parameter space compared to searches for strongly interacting supersymmetric particle partners. We discuss the implications of a mass determination for the lightest Higgs boson in the range 123<M _h <127?GeV, inspired by the intriguing hints reported by the ATLAS and CMS Collaborations, as well as those of a non-observation of the lightest Higgs boson for MSSM scenarios not excluded at the end of 2012 by LHC and direct dark matter searches and their implications on LHC SUSY searches.     

Review of searches for Higgs bosons and beyond the Standard Model Physics at the Tevatron

The energy frontier is currently at the Fermilab Tevatron accelerator, which collides protons and antiprotons at a center-of-mass energy of 1.96 TeV. The luminosity delivered to the CDF and DØ experiments has now surpassed the 4 fb^?1. This paper reviews the most recent direct searches for Higgs bosons and beyond-the-standard-model (BSM) physics at the Tevatron. The results reported correspond to an integrated luminosity of up to 2.5 fb^?1 of Run II data collected by the two Collaborations. Searches covered include the standard model (SM) Higgs boson (including sensitivity projections), the neutral Higgs bosons in the minimal supersymmetric extension of the standard model (MSSM), charged Higgs bosons and extended Higgs models, supersymmetric decays that conserve or violate R-parity, gauge-mediated supersymmetric breaking models, long-lived particles, leptoquarks, compositeness, extra gauge bosons, extra dimensions, and finally signature-based searches. Given the excellent performance of the collider and the continued productivity of the experiments, the Tevatron physics potential looks promising for discovery with the coming larger data sets. In particular, evidence for the SM Higgs boson could be obtained if its mass is light or near 160 GeV. The observed (expected) upper limits are currently a factor of 3.7 (3.3) higher than the expected SM Higgs boson cross section at m _H =115 GeV and 1.1 (1.6) at m _H =160 GeV at 95% C.L.     

Exploring the SUSY Higgs sector ate +e− linear colliders: a synopsis

We discuss the Higgs scenario in the minimal supersymmetric extension of the Standard Model ate ⁺e^? linear colliders operating in the c.m. energy range between 300 and 500 GeV. Besides decays of the Higgs particles into ordinary fermions and cascade decays, we analyze also decays into gaugino/Higgsinos and in particular, neutral Higgs decays into the lightest supersymmetric particles which are invisible ifR-parity is conserved. The cross sections for the various production channels of SUSY Higgs particles ine ⁺e^? collisions are discussed in detail. The lightest Higgs boson cannot escape detection, and in major parts of the MSSM parameter space all five Higgs particles can be observed.     

Inverse seesaw in NMSSM and 126 GeV Higgs boson

We consider extensions of the next-to-minimal supersymmetric model (NMSSM) in which the observed neutrino masses are generated through a TeV scale inverse seesaw mechanism. The new particles associated with this mechanism can have sizable couplings to the Higgs field which can yield a large contribution to the mass of the lightest CP-even Higgs boson. With this new contribution, a 126 GeV Higgs is possible along with order of 200 GeV masses for the stop quarks for a broad range of tan β. The Higgs production and decay in the diphoton channel can be enhanced due to this new contribution. It is also possible to solve the little hierarchy problem in this model without invoking a maximal value for the NMSSM trilinear coupling and without severe restrictions on the value of tan β.     

The higgs boson mass from precision electroweak data

We present a new global fit to precision electroweak data, including new low- and high-energy data and analyzing the radiative corrections arising from the minimal symmetry breaking sectors of the Standard Model (SM) and its supersymmetric extension (MSSM). It is shown that present data favor a Higgs mass ofO(M _z):M _H=76 _?50 ⁺¹⁵² GeV. We confront our analysis with (meta) stability and perturbative bounds on the SM Higgs mass, and the theoretical upper bound on the MSSM Higgs mass. Present data do not discriminate significantly between the SM and MSSM Higgs mass ranges. We comment in passing on the sensitivity of the Higgs mass determination to the values ofα(M _z) andα _s(M _z).     

Triviality bound on lightest Higgs mass in next to minimal supersymmetric model

We study the implication of triviality on Higgs sector in next to minimal supersymmetric model (NMSSM) using variational field theory. It is shown that the mass of the lightest Higgs boson in NMSSM has an upper bound ∼10M _W which is of the same order as that in the standard model.     

Relation between heat kernel method and scattering spectral method

Taking into account the available accelerator and astrophysical constraints, the mass of the lightest neutral Higgs boson h in the minimal supersymmetric extension of the Standard Model with universal soft supersymmetry-breaking masses (CMSSM) has been estimated to lie between 114 and ??130?GeV. Recent data from ATLAS and CMS hint that m _h ??125?GeV, though m _h ??119?GeV may still be a possibility. Here we study the consequences for the parameters of the CMSSM and direct dark matter detection if the Higgs hint is confirmed, focusing on the strips in the (m _1/2,m ₀) planes for different tan?? and A ₀ where the relic density of the lightest neutralino ?? falls within the range of the cosmological cold dark matter density allowed by WMAP and other experiments. We find that if m _h ??125?GeV focus-point strips would be disfavoured, as would the low-tan?? ${\tilde{\tau}}$ ?C?? and ${\tilde{t}}_{1} $ ?C?? coannihilation strips, whereas the ${\tilde{\tau}}$ ?C?? coannihilation strip at large tan?? and A ₀>0 would be favoured, together with its extension to a funnel where rapid annihilation via direct-channel H/A poles dominates. On the other hand, if m _h ??119?GeV more options would be open. We give parameterisations of WMAP strips with large tan?? and fixed A ₀/m ₀>0 that include portions compatible with m _h =125?GeV, and present predictions for spin-independent elastic dark matter scattering along these strips. These are generally low for models compatible with m _h =125?GeV, whereas the XENON100 experiment already excludes some portions of strips where m _h is smaller.     

Quasifixed-point scenario in a modified nonminimal supersymmetric standard model

The modified next-to-minimal supersymmetric standard model is the simplest model that is obtained as an extension of the minimal supersymmetric standard model and which is compatible with the LEP II experimental constraint on the mass of the lightest Higgs boson at tan β～1. The renormalization of Yukawa coupling constants and of the parameters of a soft breakdown of supersymmetry is investigated within this model. The possibility of unifying the Yukawa coupling constants for the b quark and the τ lepton at the Grand Unification scale M _X is studied. The spectrum of particles is analyzed in the vicinity of a quasifixed point where solutions to the renormalization-group equations are concentrated at the electroweak scale.     

Particle mass limits in minimal and nonminimal supersymmetric models

A review of the Higgs and neutralino sector of supersymmetric models is presented. This includes the upper limit on the mass of the lightest Higgs boson in the minimal supersymmetric standard model, as well as models based on the standard model gauge groupSU(2) _L xU(l) _Y with extended Higgs sectors. We then discuss the Higgs sector of left-right supersymmetric models, which conserveR-parity as a consequence of gauge invariance, and present a calculable upper bound on the mass of the lightest Higgs boson in these models. We also discuss the neutralino sector of general supersymmetric models based on the SM gauge group. We show that, as a consequence of gauge coupling unification, an upper bound on the mass of the lightest neutralino as a function of the gluino mass can be obtained.     

Supersymmetric relics from the big bang

We consider the cosmological constraints on supersymmetric theories with a new, stable particle. Circumstantial evidence points to a neutral gauge/Higgs fermion as the best candidate for this particle, and we derive bounds on the parameters in the lagrangian which govern its mass and couplings. One favored possibility is that the lightest neutral supersymmetric particle is predominantly a photino $\text{～}\text{γ}$ with mass above $\text{1}\text{2}$ GeV, while another is that the lightest neutral supersymmetric particle is a Higgs fermion with mass above 5 GeV or less than O(100) eV. We also point out that a gravitino mass of 10 to 100 GeV implies that the temperature after completion of an inflationary phase cannot be above 10¹⁴ GeV, and probably not above 3 × 10¹² GeV. This imposes constraints on mechanisms for generating the baryon number of the universe.     

Non-decoupling effects in supersymmetric Higgs sectors

A wide class of Higgs sectors is investigated in supersymmetric standard models. When the lightest Higgs boson (h  ) looks the standard model one, the mass (mh$m_h$) and the triple Higgs boson coupling (the hhh   coupling) are evaluated at the one-loop level in each model. While mh$m_h$ is at most 120–130 GeV in the minimal supersymmetric standard model (MSSM), that in models with an additional neutral singlet or triplet fields can be much larger. The hhh coupling can also be sensitive to the models: while in the MSSM the deviation from the standard model prediction is not significant, that can be 30–60% in some models such as the MSSM with the additional singlet or with extra doublets and charged singlets. These models are motivated by specific physics problems like the μ-problem, the neutrino mass, the scalar dark matter and so on. Therefore, when h   is found at the CERN Large Hadron Collider, we can classify supersymmetric models by measuring mh$m_h$ and the hhh coupling accurately at future collider experiments.     

Infrared quasifixed solutions in a nonminimal supersymmetric standard model

The constraints from LEPII on the mass of the lightest Higgs boson are such that, in the parameter space of the minimal supersymmetric standard model (MSSM), a considerable part of the region that corresponds to the scenario of an infrared fixed point is virtually ruled out by available experimental data. In a nonminimal supersymmetric standard model (NMSSM), the mass of the lightest Higgs boson takes its maximum value in the regime of strong Yukawa coupling, in which case the Yukawa coupling constants are much greater than the gauge coupling constants at the Grand Unification scale $(Y_i (0) \gg \tilde \alpha _i (0))$ . In this limiting case, solutions to the renormalization-group equations are attracted to Hill and infrared fixed lines or surfaces in the space of Yukawa coupling constants; for Y _i (0) → ∞, they are concentrated in the vicinities of quasifixed points. However, this attraction is quite weak. For this reason, solutions to the renormalization-group equations are grouped near some line on the Hill surface when all Y _i (0) are close to unity. Approximate solutions for the Yukawa coupling constants within the NMSSM are presented. In addition, the possibility of unifying the Yukawa coupling constants for the b quark and the τ lepton at the scale M _X is discussed.     

Higher-order corrections to Higgs boson decays in the MSSM with complex parameters

We discuss Higgs boson decays in the CP-violating MSSM, and examine their phenomenological impact using cross section limits from the LEP Higgs searches. This includes a discussion of the full 1-loop results for the partial decay widths of neutral Higgs bosons into lighter neutral Higgs bosons (h _a →h _b h _c ) and of neutral Higgs bosons into fermions (\(h_{a} \to f \bar{f}\)). In calculating the genuine vertex corrections, we take into account the full spectrum of supersymmetric particles and all complex phases of the supersymmetric parameters. These genuine vertex corrections are supplemented with Higgs propagator corrections incorporating the full 1-loop and the dominant 2-loop contributions, and we illustrate a method of consistently treating diagrams involving mixing with Goldstone and Z bosons. In particular, the genuine vertex corrections to the process h _a →h _b h _c are found to be very large and, where this process is kinematically allowed, can have a significant effect on the regions of the CPX benchmark scenario which can be excluded by the results of the Higgs searches at LEP. However, there remains an unexcluded region of CPX parameter space at a lightest neutral Higgs boson mass of ～45 GeV. In the analysis, we pay particular attention to the conversion between parameters defined in different renormalisation schemes and are therefore able to make a comparison to the results found using renormalisation group improved/effective potential calculations.     

Higgs and supersymmetry

Global frequentist fits to the CMSSM and NUHM1 using the MasterCode framework predicted M _h ?119 GeV in fits incorporating the (g?2) _μ constraint and ?126 GeV without it. Recent results by ATLAS and CMS could be compatible with a Standard Model-like Higgs boson around M _h ?125 GeV. We use the previous MasterCode analysis to calculate the likelihood for a measurement of any nominal Higgs mass within the range of 115 to 130 GeV. Assuming a Higgs mass measurement at M _h ?125 GeV, we display updated global likelihood contours in the (m ₀,m _1/2) and other parameter planes of the CMSSM and NUHM1, and present updated likelihood functions for $m_{\tilde{g}}, m_{\tilde{q}_{R}}We perform a determination of the strong coupling constant using the latest ATLAS inclusive jet cross section data, from proton?Cproton collisions at $\sqrt{s}=7~\mathrm{TeV}$ , and their full information on the bin-to-bin correlations. Several procedures for combining the statistical information from the different data inputs are studied and compared. The theoretical prediction is obtained using NLO QCD, and it also includes non-perturbative corrections. Our determination uses inputs with transverse momenta between 45 and 600?GeV, the running of the strong coupling being also tested in this range. Good agreement is observed when comparing our result with the world average at the Z-boson scale, as well as with the most recent results from the Tevatron.     

Nambu sum rule in the NJL Models: from superfluidity to top quark condensation

It may appear that the recently found resonance at 125 GeV is not the only Higgs boson. We point out the possibility that the Higgs bosons appear in models of top-quark condensation, where the masses of the bosonic excitations are related to the top quark mass by the sum rule similar to the Nambu sum rule of the NJL models [1]. This rule was originally considered by Nambu for superfluid ³He-B and for the BCS model of superconductivity. It relates the two masses of bosonic excitations existing in each channel of Cooper pairing to the fermion mass. An example of the Nambu partners is provided by the amplitude and the phase modes in the BCS model describing Cooper pairing in the s-wave channel. This sum rule suggests the existence of the Nambu partners for the 125 GeV Higgs boson. Their masses can be predicted by the Nambu sum rule under certain circumstances. For example, if there are only two states in the given channel, the mass of the Nambu partner is ～ 325 GeV. They together satisfy the Nambu sum rule M ₁ ² + M ₂ ² = 4M _t ² , where M _t ～ 174 GeV is the mass of the top quark. If there are two doubly degenerated states, then the second mass is ～210 GeV. In this case the Nambu sum rule is 2M ₁ ² + 2M ₂ ² = 4M _t ² . In addition, the properties of the Higgs modes in superfluid ³He-A, where the symmetry breaking is similar to that of the Standard Model of particle physics, suggest the existence of two electrically charged Higgs particles with masses around 245 GeV, which together also obey the Nambu sum rule M ₊ ² + M _? ² = 4M _t ² .     

Frequentist analysis of the parameter space of minimal supergravity

We make a frequentist analysis of the parameter space of minimal supergravity (mSUGRA), in which, as well as the gaugino and scalar soft supersymmetry-breaking parameters being universal, there is a specific relation between the trilinear, bilinear and scalar supersymmetry-breaking parameters, A ₀=B ₀+m ₀, and the gravitino mass is fixed by m _3/2=m ₀. We also consider a more general model, in which the gravitino mass constraint is relaxed (the VCMSSM). We combine in the global likelihood function the experimental constraints from low-energy electroweak precision data, the anomalous magnetic moment of the muon, the lightest Higgs boson mass M _h , B physics and the astrophysical cold dark matter density, assuming that the lightest supersymmetric particle (LSP) is a neutralino. In the VCMSSM, we find a preference for values of m _1/2 and m ₀ similar to those found previously in frequentist analyses of the constrained MSSM (CMSSM) and a model with common non-universal Higgs masses (NUHM1). On the other hand, in mSUGRA we find two preferred regions: one with larger values of both m _1/2 and m ₀ than in the VCMSSM, and one with large m ₀ but small m _1/2. We compare the probabilities of the frequentist fits in mSUGRA, the VCMSSM, the CMSSM and the NUHM1: the probability that mSUGRA is consistent with the present data is significantly less than in the other models. We also discuss the mSUGRA and VCMSSM predictions for sparticle masses and other observables, identifying potential signatures at the LHC and elsewhere.     

The semi-constrained NMSSM in light of muon g-2,LHC,and dark matter constraints

The semi-constrained NMSSM(scNMSSM) extends the MSSM by a singlet field, and requires unification of the soft SUSY breaking terms in the squark and slepton sectors, while it allows that in the Higgs sector to be different. We try to interpret the muon g-2 in the sc NMSSM, under the constraints of 125 Ge V Higgs data, B physics,searches for low and high mass resonances, searches for SUSY particles at the LHC, dark matter relic density by WMAP/Planck, and direct searches for dark matter by LUX, XENON1T, and PandaX-II. We find that under the above constraints, the sc NMSSM can still(i) satisfy muon g-2 at 1σ level, with a light muon sneutrino and light chargino;(ii) predict a highly-singlet-dominated 95 GeV Higgs, with a diphoton rate as hinted at by CMS data,because of a light higgsino-like chargino and moderate λ;(iii) get low fine tuning from the GUT scale with smallμeff, M_0, M_(1/2), and A_0, with a lighter stop mass which can be as low as about 500 GeV, which can be further checked in future studies with search results from the 13 TeV LHC;(iv) have the lightest neutralino be singlino-dominated or higgsino-dominated, while the bino and wino are heavier because of high gluino bounds at the LHC and universal gaugino conditions at the GUT scale;(v) satisfy all the above constraints, although it is not easy for the lightest neutralino, as the only dark matter candidate, to get enough relic density. Several ways to increase relic density are discussed.