The evolution of gaugino masses and the SUSY threshold

Anselmo, F.; Cifarelli, L.; Peterman, A.; Zichichi, A.

doi:10.1007/bf02730795

Cited by 48 publications

(32 citation statements)

References 42 publications

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“…2 As was pointed in Ref. [19], this bound is consistent with the one obtained including the impact of the evolution of gaugino masses (EGM) in the step-function approximation [20]; the lower bound on α 3 (m Z ) (upper bound on α −1 3 (m Z )) comes from taking m 1/2 ≈ 45 GeV , for which the EGM effect is small. This does not occur with the "mass dependent" effect, which gives differences of order 13%, no matter the region of masses we take.…”

Section: Submitted To Physics Letters Bsupporting

confidence: 86%

Influence of light and heavy thresholds on SUSY unification

Bastero-Gil

Pérez–Mercader

1994

Physics Letters B

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In this paper we study and compare susy unification using two different approaches in order to take into account the effect of light particle thresholds on the evolution of gauge couplings: the step-function approximation, on the one hand, and a mass dependent procedure, which gives a more accurate description of the dependence of the results on the masses, on the other. We also include the effect of heavy thresholds, when SU (5) is chosen as the unifying group. We find that the massdependent procedure excludes scenarios where all susy masses are below 1 T eV , and favors a value of α 3 (m Z ) near its upper experimental bound, contrary to the results obtained with the step-function approximation. We underline the dependence of the results on the procedure chosen to deal with light thresholds.

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Section: Submitted To Physics Letters Bsupporting

confidence: 86%

Influence of light and heavy thresholds on SUSY unification

Bastero-Gil

Pérez–Mercader

1994

Physics Letters B

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“…Since the sparticle masses vary as one explores the parameter space, one obtains ranges for the calculated values. In Table 2 we show the one-loop value for M U (M U ) [as expected [14] M U is reduced by both effects], the ratio of the two, and the calculated range of sin 2 θ w . 1 Note that for α 3 = 0.118 (and lower), sin 2 θ w is outside the experimental ±1σ range U , the ratio of the two, and the range of the calculated sin 2 θ w , for the indicated values of α 3 (the superscript + (−) denotes µ > 0 (< 0)) and α −1 e = 127.9.…”

Section: Gauge and Yukawa Coupling Unificationmentioning

confidence: 77%

“…In fact, the whole concept of a single unification point needs to be abandoned. The upshot of all this is that the theoretical uncertainties on the values of the parameters describing the heavy GUT particles are such that the above prediction for M SU SY [8] is washed out completely [14,15]. Furthermore, the insertion of a realistic spectrum of sparticles at low energies (as opposed to an unrealistic common M SU SY mass) plus the calculation of the EGM Figure 1: In this well publicized example of unification of couplings ( Fig.…”

Section: Introductionmentioning

confidence: 98%

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Status of the superworld from theory to experiment

López

Nanopoulos

Zichichi

1994

Progress in Particle and Nuclear Physics

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Among the most outstanding conceptual developments in particle physics we have: the unification of all particle interactions at very-high energies (Grand Unification), the fermion-boson symmetry (Supersymmetry), the non-point-like structure of elementary particles (String theory), and the understanding that all dynamical quantities (gauge couplings, masses, Yukawa couplings) run with energy (Renormalization Group Equations). The goal is to make use of these great developments to construct a theory which embraces all fundamental forces of Nature, including gravity. In this review we address this problem and its possible implications for physics in the energy range where our experimental facilities operate. We show that what is required are not qualitative arguments but a set of detailed calculations with definite predictions. This is why we have chosen two specific Supergravity models: SU(5) and SU(5)×U(1). One as representative of Field Theory, the other of String Theory. This kind of model-building at the Planck scale seems to tell us that new physics beyond the Standard Model could be near the Fermi scale. Therefore detailed calculations for existing facilities (Tevatron, LEP I-II, HERA, Gran Sasso, Super Kamiokande, Dumand, Amanda, etc.) are a definite way to put string theory -i.e., the existence of the Superworld -under experimental test, now. December 1993 14 Conclusions 77 Acknowledgements 78 References 82 b ij =    199 25 27 5 88 5 9 5 25 24 11 51 We should note that these ranges are obtained after all constraints discussed below have been satisfied, the proton decay being the most important one.

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“…This prediction [10] for the likely scale of the supersymmetric spectrum (i.e., M SU SY ∼ 1 TeV [10]) is in fact incorrect [13]. The reason is simple: the physics at the unification scale, which is used to predict the value of M SU SY , has been ignored completely.…”

Section: Convergence Of Gauge Couplings: Geometry Versus Physicsmentioning

confidence: 99%

A Layman’s guide toSUSY Guts

1994

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The determination of the most straightforward evidence for the existence of the Superworld requires a guide for non-experts (especially experimental physicists) for them to make their own judgement on the value of such predictions. For this purpose we review the most basic results of Super-Grand unification in a simple and clear way. We focus the attention on two specific models and their predictions. These two models represent an example of a direct comparison between a traditional unified-theory and a string-inspired approach to the solution of the many open problems of the Standard Model. We emphasize that viable models must satisfy all available experimental constraints and be as simple as theoretically possible. The two well defined supergravity models, SU(5) and SU(5) × U(1), can be described in terms of only a few parameters (five and three respectively) instead of the more than twenty needed in the MSSM model, i.e., the Minimal Supersymmetric extension of the Standard Model. A case of special interest is the strict no-scale SU(5) × U(1) supergravity where all predictions depend on only one parameter (plus the top-quark mass). A general consequence of these analyses is that supersymmetric particles can be at the verge of discovery, lurking around the corner at present and near future facilities. This review should help anyone distinguish between well motivated predictions and predictions based on arbitrary choices of parameters in undefined models.

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The evolution of gaugino masses and the SUSY threshold

Cited by 48 publications

References 42 publications

Influence of light and heavy thresholds on SUSY unification

Influence of light and heavy thresholds on SUSY unification

Status of the superworld from theory to experiment

A Layman’s guide toSUSY Guts

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