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P. N. Pandita 《Pramana》1998,51(1-2):169-180
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. 相似文献
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The Higgs sectors of supersymmetric extensions of the Standard Model have two doublets in the minimal version (MSSM), and
two doublets plus a singlet in two others: with (UMSSM) and without (NMSSM) an extra U(1)′. A very concise comparison of these three models is possible if we assume that the singlet has a somewhat larger breaking
scale compared to the electroweak scale. In that case, the UMSSM and the NMSSM become effectively two-Higgs-doublet models
(THDM), like the MSSM. In this approach the well-known upper mass bounds on the lightest CP-even neutral Higgs boson can be
derived in a very simple and transparent way. 相似文献
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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. 相似文献
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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. 相似文献
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We consider the renormalisation group flow of gauge couplings within the so-called exceptional supersymmetric Standard Model (E6SSM) based on the low-energy matter content of 27-dimensional representations of the gauge group E6, together with two additional non-Higgs doublets. The two-loop beta functions are computed, and the threshold corrections are studied in the E6SSM. Our results show that gauge coupling unification in the E6SSM can be achieved for phenomenologically acceptable values of α3(MZ), consistent with the central measured low-energy value, unlike in the minimal supersymmetric Standard Model (MSSM) which, ignoring the effects of high energy threshold corrections, requires significantly higher values of α3(MZ), well above the experimentally measured central value. 相似文献
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R. Barbieri S. Ferrara L. Maiani F. Palumbo C.A. Savoy 《Physics letters. [Part B]》1982,115(3):212-216
We derive the general formula for the supertrace of the quartic mass matrix in a general supersymmetric gauge theory, with arbitrary representations for the chiral multiplets. This formula clarifies the non-renormalization theorems in presence of gauge interactions and gives “extended renormalization theorems” for N = 2 and N = 4 supersymmetric Yang-Mills theories. In particular we find the known result that gren = gbare for the N = 4 theory and the new result mren = mbare for the N = 2 gauge interactions of massive hypermultiplets. We give arguments to the extent that the latter non-renormalization theorem persists to all orders in perturbation theory. 相似文献
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《Comptes Rendus Physique》2007,8(9):999-1012
We review the realization of the Brout–Englert–Higgs mechanism in the electroweak theory and describe the experimental and theoretical constraints on the mass of the single Higgs boson expected in the minimal Standard Model. We also discuss the couplings of this Higgs boson and its possible decay modes as functions of its unknown mass. We then review the structure of the Higgs sector in the minimal supersymmetric extension of the Standard Model (MSSM), noting the importance of loop corrections to the masses of its five physical Higgs bosons. Finally, we discuss some non-minimal models. To cite this article: J. Ellis et al., C. R. Physique 8 (2007). 相似文献
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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. 相似文献
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P. N. Pandita 《Zeitschrift fur Physik C Particles and Fields》1993,59(4):575-583
We calculate the dominant one-loop radiative corrections arising from quark-squark loops to the mass squared matrix of theCP-even Higgs bosons in a non-minimal supersymmetric Standard Model containing two Higgs doublets and a Higgs singlet chiral superfield using one-loop effective potential approximation. We use this result to evaluate upper and lower bounds on the radiatively corrected masses of all the scalar Higgs bosons as a function of the parameters of the model. We find that the one-loop radiative corrections are substantial only for the lightest Higgs boson of the model and can push its mass beyond the reach of LEP. We also calculate an absolute upper bound on the mass of the radiatively corrected lightest Higgs boson and compare it with the corresponding bound in the minimal supersymmetric Standard Model. 相似文献
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《Nuclear Physics B》1998,532(3):529-566
The lowest representatives of the form factors relative to the trace operators of N = 1 super sinh-Gordon model are exactly calculated. The novelty of their determination consists in solving a coupled set of unitarity and crossing equations. Analytic continuations of the form factors as functions of the coupling constant allows for the study of interesting models in a uniform way, among these the latest model of the Roaming series and the minimal supersymmetric models as investigated by Schoutens. A fermionic version of the c-theorem is also proved and the corresponding sum rule derived. 相似文献
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We formulate a general sufficiency criterion for discreteness of the spectrum of both supersymmmetric and non-supersymmetric theories with a fermionic contribution. This criterion allows an analysis of Hamiltonians in complete form rather than just their semiclassical limits. In such a framework we examine spectral properties of various (1+0) matrix models. We consider the BMN model of M-theory compactified on a maximally supersymmetric pp-wave background, different regularizations of the supermembrane with central charges and a non-supersymmetric model comprising a bound state of N D2 with m D0. While the first two examples have a purely discrete spectrum, the latter has a continuous spectrum with a lower end given in terms of the monopole charge. 相似文献
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Finite-temperature properties of the two-doublet extension of the scalar sector of the Standard Model and its special features
concerning the electroweak phase transition are considered. Critical conditions for the temperature evolution of the effective
potential in the two-doublet model that lead to a strong first-order phase transition, which is necessary for the generation
of the observed baryon-antibaryon asymmetry, are determined. 相似文献