Weak symmetry breaking by radiative corrections in broken supergravity

Comptes Rendus Physique, 2007

We review the mechanism of radiative electroweak symmetry breaking taking place in SUSY versions of the standard model. We further discuss different proposals for the origin of SUSY-breaking and the corresponding induced SUSY-breaking soft terms. Several proposals for the understanding of the little hierarchy problem are critically discussed.

Nuovo Cimento Della Societa Italiana Di Fisica A-nuclei Particles and Fields, 1986

The Higgs sector of a model with a softly broken supersymmetry is studied in detail. Our main result is that, in contrasts to the standard non-supersymmetric model, the stability of the vacuum does not impose any lower bound to the Higgs mass. Attraverso lo studio delle correzioni radiative ad un loop al Potenziale effettivo, abbiamo studiato la possibilità di ottenere radiativamente rottura spontanea della simmetria SU2×1 in un modello di gauge con una supersimmetria rotta esplicitamente. Abbiamo veriflcato che la Stabilità del vuoto, a differenza di quanto avviene nel modello standard, non induce alcun limite inferiore per la massa del bosone di Higgs, ma che tale bosone può essere arbitrariamente leggero puchè i parametri di rottura della supersimmetria siano sufficientemente piccoli rispetto alla scala delle interazioni deboli.

Nuclear Physics B, 1993

We discuss several aspects of state-of-the-art calculations of radiative electroweak symmetry breaking in supergravity models. These models have a five-dimensional parameter space in contrast with the 21-dimensional one of the MSSM. We examine the 1-Iiggs one-loop effective potential~= V 0 + zlV, in particular how its renormalization-scale (Q) independence is affected by the approximation used to calculate iIV and by the presence of a Higgs-field-independent term which makes l/~(0) 0. We show that the latter must be subtracted Out to achieve Q-independence. We also discuss our own approach to the exploration of the five-dimensional parameter space and the tine-tuning constraints within this approach. We apply our methods to the determination of the allowed region in parameter space of two models which we argue to be the prototypes for conventional (SSM) and string (SISM) unified models. To this end we impose the electroweak breaking constraint by minimizing the one-loop effective potential and study the shifts in jx and B relative to the values obtained using the tree-level potential. These shifts are most significant for small values of~s and B, and induce corresponding shifts on the lightest jxand/or B-dependent particle masses, i.e., those of the lightest stau, neutralino, chargino, and Higgs boson states. Finally, we discuss the predictions for the squark, slepton, and one-loop corrected Higgs boson masses. * The parameters in V0 must satisfy further consistency constraints to insure that this is a true minimum of the tree-level Higgs potential. As discussed in ref. 1121 (and below), the one-loop effective potential satisfies most of these constraints automatically.

Physics Letters B, 1984

We present a cosmologically acceptable grand unified model where the breaking of SU(5) proceeds through radiative corrections induced by supergravity soft-breaking terms. The breaking scale is determined by dimensional transmutation. The model is compatible with the radiative breaking of SU(2) L × U(1)y which provides an experimentally accessible low energy particle spectrum and small top quark mass. Two mechanisms have so far been proposed for the breaking of SU(2) × U(1) within the context of spontaneously broken N = 1 supergravity. Both of them are based on quantum corrections induced by the soft breaking terms which come from the super-Higgs effect in N = 1 supergravity [ 1 ] : (a) The scaling of parameters of the tree level potential [2-5]. In this case, the scale of global supersymmetry (SUSY) breaking, m3/2, is close to the

Physical Review D, 1994

We perform a systematic study of radiative corrections to the masses of the Higgs bosons in the minimal supersymmetric standard model (MSSM) augmented by a single gauge singlet, the so-called next-to-minimal supersymmetric standard model (NMSSM). Our method is based on the one-loop effective potential and includes effects of top quark, squark, Higgs and Higgsino loops. We discuss the renormalisation group flows of Yukawa couplings and the upper bound on the lightest CP-even neutral Higgs boson mass as a function of the heavier stop mass and top mass. We then give a general discussion of Higgs boson phenomenology including radiative corrections. We survey as much of the parameter space of the Higgs sector of the NMSSM as is practicable, and analyse the full spectrum of Higgs masses and couplings in these regions of parameter space. Characteristic signatures of the NMSSM such as light charged bosons and weakly coupled neutral scalars are discussed, as are the relative sizes of the various radiative corrections. The MSSM is also discussed as a limiting case of the NMSSM for comparison.

We re-examine our former predictions \cite{kahanath1,kahanath2} of the top and Higgs masses via dynamical symmetry breaking in a 4-fermion theory which produces the Higgs as a bound state, and relates the top and Higgs masses to $m_W$. The use of dynamical symmetry breaking was stongly motivated by the apparent equality, within a factor of two, of the known and expected masses of the $W$, $Z$, top and Higgs. In later work \cite{kahanath2} we evaluated the masses self-consistently at the mass-poles, which resulted in predictions of $m_t \sim 175$ GeV, and $m_H \sim 125$ GeV as central values within ranges produced by varying the measured strong coupling. Figures (1) and (2) result from evolution down to $m_W$ while the number quoted for the top quark mass, i.e. 175 GeV includes an evolution back up to the top and use of the determination of $\alpha_s$ at LEP at that time. $m_H$ is less dependent on the value of the strong coupling. The variation of the predicted masses for a range of...

Physics Letters B, 1991

In a general softly broken supcrsymmetric theory with Higgs doublets only, we calculate the radiative corrections to the mass of the lightcst neutral ttiggs boson in the particular case where all the extra particles introduced by supersymmetry are close in mass and all heavier than the Fermi scale. In this situation the corrections are large and trivially calculable. We also consider the limiting case in which all the superpartners become arbitrarily heavy. The connection of these considerations with the Higgs of the standard model is elucidated.

Nuclear Physics B, 1979

The super Higgs effect is studied in the (2, $) + (&, O+, OK) model. The most general action is obtained using the recently developed tensor calculus: it contains an arbitrary function of two variables Q(A, B), A and B being the O+ scalar and O-pseudoscalar fields of the matter system. The conditions are given which 9 must satisfy in order that both the gravitino $J,, becomes massive and no cosmological yrn is*induced. Explicit examples are given, a class of them leading to the mass formula mA + mg = 4m$, .

Symmetry, 2018

Finite Unified Theories (FUTs) are N = 1 supersymmetric Grand Unified Theories, which can be made finite to all orders in perturbation theory, based on the principle of the reduction of couplings. The latter consists of searching for renormalization group invariant relations among parameters of a renormalizable theory holding to all orders in perturbation theory. FUTs have proven very successful so far. In particular, they predicted the top quark mass one and half years before its experimental discovery, while around five years before the Higgs boson discovery, a particular FUT was predicting the light Higgs boson in the mass range ∼121-126 GeV, in striking agreement with the discovery at LHC. Here, we review the basic properties of the supersymmetric theories and in particular finite theories resulting from the application of the method of reduction of couplings in their dimensionless and dimensionful sectors. Then, we analyze the phenomenologically-favored FUT, based on SU(5). This particular FUT leads to a finiteness constrained version of the Minimal SUSY Standard Model (MSSM), which naturally predicts a relatively heavy spectrum with colored supersymmetric particles above 2.7 TeV, consistent with the non-observation of those particles at the LHC. The electroweak supersymmetric spectrum starts below 1 TeV, and large parts of the allowed spectrum of the lighter might be accessible at CLIC. The FCC-hhwill be able to fully test the predicted spectrum.

Nuclear Physics B, 1985

Spontaneous violation of lepton number without breaking Lorentz invariance can, in principle, be incorporated in models with softly broken supersymmetry. We study the situation for minimal low-energy supergravity models coming from a GUT (hence not having hierarchy destabilizing light singlets) and where the SU(2) × U(1) breaking is radiative. It is found that for this type of model, R-parity breaking requires either too heavy a top quark for a realistic superpartner spectrum or too light a superpartner spectrum for a realistic top quark, making the spontaneous violation of lepton number in the third generation incompatible with present experimental data. We do not discard the possibility of having it in a fourth, heavier, generation. * Supported in part by "Comisi6n Asesora de Investigaci6n Cientifica y Trcnica" under contract 3209.