Dimensional transmutation in broken supergravity

No-scale supersymmetric standard model

We discuss the Higgs sector of the minimal supersymmetric standard model including effects of radiative corrections. The formalism is explained in detail for computing radiative corrections to the masses and the coupling constants of the Higgs bosons. The radiative corrections to the masses are studied in the on-shell renormalization scheme. The radiative corrections to the mixing angles between the two CP-even Higgs bosons and the Higgs self-coupling constants are investigated in a simple procedure. The explicit analytic expressions are given for the radiative corrections due to the loops containing the top and bottom quarks and their superpartners. Simple approximate formulae are derived from the analytic expressions obtained in the on-shell renormalization scheme. We numerically study the effects of radiative corrections on the mass of the lighter Higgs boson and the mixing angles between the two CP-even Higgs bosons.

In the minimal supersymmetric model (MSSM), the Higgs self-interactions are related to the SU L (2) × U Y (1) gauge couplings. These relations impose an upper limit on the mass of the lightest Higgs boson of the model. When one-loop radiative corrections to this limit are included, one finds that the corrections are large and grow logarithmically with the supersymmetry breaking scale. Renormalization group techniques are employed in order to sum the leading log radiative corrections to all orders, and the result is that m h o — m Z converges to an infrared fixed point. However, due to the m t 4 behavior of the dominant term, the radiative corrections can still lift the upper bound on the lightest Higgs mass above the reach of LEP-200. The radiatively corrected upper bound for m h o as a function of mt is presented.

We study the radiative symmetry breaking of B-L in supersymmetric models with\ninverse seesaw mechanism. We show that for a wide region of parameter space the\nradiative corrections can drive the squared mass of the extra Higgs boson from\npositive initial values at the GUT scale to negative values at the TeV scale,\nleading to the spontaneous breaking of the B-L symmetry. We also emphasize that\nin this class of models, unlike the supersymmetric B-L models with type I\nseesaw, the right-handed sneutrino cannot get a non-zero vacuum expectation\nvalue. Therefore, B-L can be radiatively broken while R-parity remains an exact\nsymmetry.\n

The small and negative value of the Standard Model Higgs quartic coupling at high scales can be understood in terms of anthropic selection on a landscape where large and negative values are favored: most universes have a very short-lived electroweak vacuum and typical observers are in universes close to the corresponding metastability boundary. We provide a simple example of such a landscape with a Peccei-Quinn symmetry breaking scale generated through dimensional transmutation and supersymmetry softly broken at an intermediate scale. Large and negative contributions to the Higgs quartic are typically generated on integrating out the saxion field. Cancellations among these contributions are forced by the anthropic requirement of a sufficiently long-lived electroweak vacuum, determining the multiverse distribution for the Higgs quartic in a similar way to that of the cosmological constant. This leads to a statistical prediction of the Higgs boson mass that, for a wide range of parameters, yields the observed value within the 1σ statistical uncertainty of ∼ 5 GeV originating from the multiverse distribution. The strong CP problem is solved and single-component axion dark matter is predicted, with an abundance that can be understood from environmental selection. A more general setting for the Higgs mass prediction is discussed.

We discuss the mass of the (physical component of the) Higgs boson in one-loop and top-quark-mass approximation. For this the minimal Standard Model is regarded as a specific (parameterized) gauge theory of Dirac type. It is shown that the latter formulation, in contrast to the usual description of the Standard Model, gives a definite value for the Higgs mass. The predicted value for the Higgs mass depends on the value addressed to the top mass mT. We obtain mH = 186 ± 8 GeV for mT = 174 ± 3 GeV (direct observation of top events), resp. mH = 184 ± 22 GeV for mT = 172 ± 10 GeV (Standard Model electroweak fit). Although the Higgs mass is predicted to be near the upper bound, mH is in full agreement with the range 114 ⩽ mH < 193 GeV that is allowed by the Standard Model. We show that the inclusion of (Dirac) massive neutrinos does not alter the results presented. We also briefly discuss how the derived mass values are related to those obtained within the frame of non-commutative geometry.

We consider an electroweak scenario for baryon asymmetry generation in an extended model with two Higgs doublets. The upper bound on the mass of the lightest Higgs boson is obtained. It is shown to coincide with that of the theory with one Higgs doublet, namely, mH&lt;mcr 45 GeV, if the masses of all Higgs bosons do not exceed the mass of the W boson substantially. Otherwise the upper bound is shown still to exist but is greater than mcr and depends on the actual values of the scalar-field self-coupling constants. © 1991 The American Physical Society.

We investigate the one-loop contributions to the mass of the SM-like Higgs boson in the MSSM considering the effect of slepton flavor mixing, which is parametrized by the dimensionless parameter δXY (X, Y = L, R) in the slepton mass matrices. For the surviving samples under the experimental constraints, we calculate the corrections to the mass of the SM-like Higgs boson in terms of δXY. We find that the mass correction Δmh can even be larger than 10 GeV for large δRL or δLR. Moreover, Δmh has strong sensitivity to δRL or δLR, while the weak sensitivity to δLL or δRR, since δRL or δLR enters directly into the coupling of Higgs boson with sleptons in the calculations of Higgs boson self-energies.

Nowadays in the MSSM the moderate values of $\\tan\\beta$ are almost excluded\nby LEP II lower bound on the lightest Higgs boson mass. In the Next-to-Minimal\nSupersymmetric Standard Model the theoretical upper bound on it increases and\nreaches maximal value in the strong Yukawa coupling limit when all solutions of\nrenormalization group equations are concentrated near the quasi-fixed point.\nFor calculation of Higgs boson spectrum the perturbation theory method can be\napplied. We investigate the particle spectrum in the framework of the modified\nNMSSM which leads to the self-consistent solution in the strong Yukawa coupling\nlimit. This model allows one to get $m_h\\sim 125$ GeV at values of\n$\\tan\\beta\\ge 1.9$. In the investigated model the lightest Higgs boson mass\ndoes not exceed $130.5\\pm 3.5$ GeV. The upper bound on the lightest CP-even\nHiggs boson mass in more complicated supersymmetric models is also discussed.\n

We obtain 95% C. L. upper limits on the ratio of triplet to doublet vacuum expectation values in two extended electroweak models from radiative corrections. We use as input data from LEP, the Tevatron, the CERN [Formula: see text] colliders, and various low-energy experiments such as atomic parity-violation and deep inelastic scattering. The analysis includes the incorporation of leading two-loop electroweak contributions to ∆r and ρ arising from heavy top quarks and Higgs bosons, the Consoli–Hollik–Jegerlehner resummation technique, and QCD corrections to the hadronic partial widths of the Z using the new value for the (αs/π)3 coefficient. Our limits are found to be only mildly sensitive to the top quark and Higgs boson masses and somewhat stronger than those obtained previously. Our results are then generalized to bounds on the allowed value of the tree-level ρ parameter.

In supersymmetric models with minimal particle content and without large left-right squarks mixing, the conventional knowledge is that the Higgs Boson mass around 125 GeV leads to top squark masses O(10) TeV, far beyond the reach of colliders. Here, we pointed out that this conclusion is subject to several theoretical uncertainties. We find that electroweak symmetry breaking and evaluation of Higgs mass at a scale far away from the true electroweak symmetry breaking scale introduce a large uncertainty in Higgs mass calculation. We show that the electroweak symmetry breaking at the scale near the true vacuum expectation value of Higgs field can increase the Higgs Boson mass about 4–5 GeV and can lower the bounds on squarks and slepton masses to 1 TeV. Here we pointed out that the Higgs mass even with inclusion of radiative corrections can vary with electroweak symmetry breaking scale. We calculate it at two loop level and show that it varies substantially. We argue that Higgs mass like other coupling parameters can vary with energy scale and the Higgs potential with all orders loop corrections is scale invariant. This uncertainty to the Higgs mass calculation due to electroweak symmetry breaking around the supersymmetry breaking scale, normally taken as mt˜Lmt˜R, to minimize the 1-loop radiative corrections can be removed if one considers all significant radiative contributions to make Higgs potential renormalization group evolution scale invariant and evaluates electroweak symmetry breaking at the scale near the electroweak symmetry breaking scale. A large parameter space becomes allowed when one considers electroweak symmetry breaking at its true scale not only for producing correct values of the Higgs masses, but also for providing successful breaking of this symmetry in more parameter spaces.

We present a comprehensive analysis of the Higgs boson spectra in several versions of the supersymmetric left--right model based on the gauge symmetry $SU(3)_c \times SU(2)_L \times SU(2)_R \times U(1)_{B-L}$. A variety of symmetry breaking sectors are studied, with a focus on the constraints placed on model parameters by the lightest neutral CP even Higgs boson mass $M_h$. The breaking of $SU(2)_R$ symmetry is achieved by Higgs fields transforming either as triplets or doublets, and the electroweak symmetry breaking is triggered by either bi--doublets or doublets. The Higgs potential is analyzed with or without a gauge singlet Higgs field present. Seesaw models of Type I and Type II, inverse seesaw models, universal seesaw models and an $E_6$ inspired alternate left--right model are included in our analysis. Several of these models lead to the tree--level relation $M_h \leq \sqrt{2}\,m_W$ (rather than $M_h \leq m_Z$ that arises in the MSSM), realized when the $SU(2)_R$ symmetry breaking scale is of order TeV. With such an enhanced upper limit, it becomes possible to accommodate a Higgs boson of mass 126 GeV with relatively light stops that mix negligibly. In models with Higgs triplets, a doubly charged scalar remains light below a TeV with its mass arising entirely from radiative corrections. We carry out the complete one--loop calculation for its mass induced by the Majorana Yukawa couplings and show the consistency of the framework. We argue that these models prefer a low $SU(2)_R$ breaking scale. Other theoretical and phenomenological implications of these models are briefly discussed.

We discuss phenomenological consequences of requiring the cancellation of one-loop quadratic divergences in corrections to scalar masses within Two-Higgs-Doublet Models (2HDM). It is shown that the Inert Doublet Model (IDM) can not accommodate the requirement of the cancellation. A general 2HDM is also analyzed taking into account existing experimental constraints. Allowed regions in the parameter space, permitting the above cancellation, are determined. A degeneracy between masses of scalar bosons is observed for tanbeta \gsim 40. The possibility for CP violation in the scalar potential is discussed and regions of tanbeta-M_{H^\pm} with substantial amount of CP violation are determined. In order to provide a source for dark matter in a minimal manner, a scalar gauge singlet is introduced and discussed. The model allows to ameliorate the little hierarchy problem by lifting the minimal scalar Higgs boson mass and by suppressing the one-loop quadratic corrections to scalar masses. The cutoff originating from the naturality arguments is therefore lifted to \gsim 15 TeV depending on the mass of the lightest scalar.

In the Glashow-Salam-Weinberg model with single Higgs doublet, upper bounds on the Higgs-boson mass and the coupling constant are obtained: ${m}_{\mathrm{H}}&lt;~455$ GeV, $\ensuremath{\lambda}&lt;~32.8$ based on one-loop radiative corrections and the existence of the spontaneously broken absolute vacuum. Under two-loop radiative corrections, these bounds are improved to ${m}_{\mathrm{H}}&lt;~320$ GeV, $\ensuremath{\lambda}&lt;~9.35$.

We study the functional behavior of the quartic scalar coupling in the standard model with four generations. From the assumed boundedness of its ratio to theU(1) gauge coupling and the stability of the Higgs potential under radiative corrections, we derive upper and lower bounds on the Higgs-boson mass as functions of the fourth-generation fermion masses. We also obtain a solution in which the Higgs-boson mass is determined as a function of the other masses of the model.