Impact of physical principles at very high energy scales on the superparticle mass spectrum (original) (raw)
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Report of the Beyond the MSSM Subgroup for the Tevatron Run II SUSY/Higgs Workshop
2000
There are many l o w-energy models of supersymmetry breaking parameters which are motivated by theoretical and experimental considerations. Some of these approaches have gained more proponents than others over time, and so have been studied in greater detail. In this contribution we discuss some of the lesser-known theories of low-energy supersymmetry, and outline their phenomenological consequences. In some cases, these theories have more gauge symmetry or particle content than the Minimal Supersymmetric Standard Model. In other cases, the parameters of the Lagrangian are unusual compared to commonly accepted norms (e.g., Wino LSP, heavy gluino LSP, light gluino, etc.). The phenomenology of supersymmetry varies greatly between the di erent models. Correspondingly, particular aspects of the detectors assume greater or lesser importance. Detection of supersymmetry and the determination of all parameters may w ell depend upon having the widest possible view of supersymmetry phenomenology. 157 122 279 (MSSM)BLV 175 140 315
Bottom-up approach and supersymmetry breaking
Nuclear Physics B, 1997
We present a bottom-up approach to the question of supersymmetry breaking in the MSSM. Starting with the experimentally measurable low-energy supersymmetry-breaking parameters, which can take any values consistent with present experimental constraints, we evolve them up to an arbitrary high energy scale. Approximate analytical expressions for such an evolution, valid for low and moderate values of tan β, are presented. We then discuss qualitative properties of the high-energy parameter space and, in particular, identify the conditions on the low energy spectrum that are necessary for the parameters at the high energy scale to satisfy simple regular pattern such as universality or partial universality. As an illustrative example, we take low energy parameters for which light sparticles, within the reach of the LEP2 collider, appear in the spectrum, and which do not affect the Standard Model agreement with the precision measurement data. Comparison between supersymmetry breaking at the GUT scale and at a low energy scale is made.
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Perturbative supersymmetry breaking on the landscape of string vacua is expected to favor large soft terms as a power-law or log distribution, but tempered by an anthropic veto of inappropriate vacua or vacua leading to too large a value for the derived weak scalea violation of the atomic principle. Indeed, scans of such vacua yield a statistical prediction for light Higgs boson mass mh ∼ 125 GeV with sparticles (save possibly light higgsinos) typically beyond LHC reach. In contrast, models of dynamical SUSY breaking (DSB)– with a hidden sector gauge coupling g2 scanned uniformly– lead to gaugino condensation and a uniform distribution of soft parameters on a log scale. Then soft terms are expected to be distributed as m−1 soft favoring small values. A scan of DSB soft terms generally leads to mh 125 GeV and sparticle masses usually below LHC limits. Thus, the DSB landscape scenario seems excluded from LHC search results. An alternative is that the exponential suppression of the wea...
Constraints on sparticle spectrum in different supersymmetry breaking models
Pramana-journal of Physics - PRAMANA-J PHYS, 2004
We derive sum rules for the sparticle masses in different models of supersymmetry breaking. This includes the gravity-mediated models (SUGRA models) as well as models in which supersymmetry breaking terms are induced by super-Weyl anomaly (AMSB models). These sum rules can help in distinguishing between these models. In particular, we obtain an upper bound on the mass of the lightest neutralino as a function of the gluino mass in SUGRA and AMSB models.
Reach of the CERN Large Hadron Collider for gauge-mediated supersymmetry breaking models
Physical Review D, 2000
We examine signals for sparticle production at the CERN Large Hadron Collider (LHC) within the framework of gauge mediated supersymmetry breaking models with a low SUSY breaking scale for four different model lines, each of which leads to qualitatively different signatures. We first examine the reach of the LHC via the canonical E T and multilepton channels that have been advocated within the mSUGRA framework. Next, we examine special features of each of these model lines that could serve to further enhance the SUSY signal over Standard Model backgrounds. We use ISAJET to evaluate the SUSY reach of experiments at the LHC. We find that the SUSY reach, measured in terms of mg, is at least as large, and sometimes larger, than in the mSUGRA framework. In the best case of the co-NLSP scenario, the reach extends to mg ≥ 3 TeV, assuming 10 f b −1 of integrated luminosity.
A simple and realistic model of supersymmetry breaking
Physics Letters B, 2008
We present a simple and realistic model of supersymmetry breaking. In addition to the minimal supersymmetric standard model, we only introduce a hidden sector gauge group SU (5) and three fields X, F andF. Supersymmetry is broken at a local minimum of the potential, and its effects are transmitted to the supersymmetric standard model sector through both standard model gauge loops and local operators suppressed by the cutoff scale, which is taken to be the unification scale. The form of the local operators is controlled by a U (1) symmetry. The generated supersymmetry breaking and µ parameters are comparable in size, and no flavor or CP violating terms arise. The spectrum of the first two generation superparticles is that of minimal gauge mediation with the number of messengers N mess = 5 and the messenger scale 10 11 GeV < ∼ M mess < ∼ 10 13 GeV. The spectrum of the Higgs bosons and third generation superparticles, however, can deviate from it. The lightest supersymmetric particle is the gravitino with a mass of order (1 − 10) GeV.
Gaugino anomaly mediated SUSY breaking: phenomenology and prospects for the LHC
Journal of High Energy Physics, 2010
We examine the supersymmetry phenomenology of a novel scenario of supersymmetry (SUSY) breaking which we call Gaugino Anomaly Mediation, or inoAMSB. This is suggested by recent work on the phenomenology of flux compactified type IIB string theory. The essential features of this scenario are that the gaugino masses are of the anomalymediated SUSY breaking (AMSB) form, while scalar and trilinear soft SUSY breaking terms are highly suppressed. Renormalization group effects yield an allowable sparticle mass spectrum, while at the same time avoiding charged LSPs; the latter are common in models with negligible soft scalar masses, such as no-scale or gaugino mediation models. Since scalar and trilinear soft terms are highly suppressed, the SUSY induced flavor and CP-violating processes are also suppressed. The lightest SUSY particle is the neutral wino, while the heaviest is the gluino. In this model, there should be a strong multi-jet +E miss
Phenomenological constraints on patterns of supersymmetry breaking
Physics Letters B, 2003
Specific models of supersymmetry breaking predict relations between the trilinear and bilinear soft supersymmetry breaking parameters A 0 and B 0 at the input scale. In such models, the value of tan β can be calculated as a function of the scalar masses m 0 and the gaugino masses m 1/2 , which we assume to be universal. The experimental constraints on sparticle and Higgs masses, b → sγ decay and the cold dark matter density Ω CDM h 2 can then be used to constrain tan β in such specific models of supersymmetry breaking. In the simplest Polonyi model with A 0 = (3 − √ 3)m 0 = B 0 + m 0 , we find 11 < ∼ tan β < ∼ 20 (tan β 4.15) for µ > 0 (µ < 0). We also discuss other models with A 0 = B 0 + m 0 , finding that only the range −1.9 < ∼ A 0 /m 0 < ∼ 2.5 is allowed for µ > 0, and the range 1.25 < ∼ A 0 /m 0 < ∼ 4.8 for µ < 0. In these models, we find no solutions in the rapid-annihilation 'funnels' or in the 'focus-point' region. We also discuss the allowed range of tan β in the no-scale model with A 0 = B 0 = 0. In all these models, most of the allowed regions are in the χ −τ 1 coannihilation 'tail'.
A solution to the supersymmetric fine-tuning problem within the MSSM
Physics Letters B, 2005
Weak scale supersymmetry has a generic problem of fine-tuning in reproducing the correct scale for electroweak symmetry breaking. The problem is particularly severe in the minimal supersymmetric extension of the standard model (MSSM). We present a solution to this problem that does not require an extension of the MSSM at the weak scale. Superparticle masses are generated by a comparable mixture of moduli and anomaly mediated contributions, and the messenger scale of supersymmetry breaking is effectively lowered to the TeV region. Crucial elements for the solution are a large A term for the top squarks and a small B term for the Higgs doublets. Requiring no fine-tuning worse than 20%, we obtain rather sharp predictions on the spectrum. The gaugino masses are almost universal at the weak scale with the mass between 450 and 900 GeV. The squark and slepton masses are also nearly universal at the weak scale with the mass a factor of √ 2 smaller than that of the gauginos. The only exception is the top squarks whose masses split from the other squark masses by about m t / √ 2. The lightest Higgs boson mass is smaller than 120 GeV, while the ratio of the vacuum expectation values for the two Higgs doublets, tan β, is larger than about 5. The lightest superparticle is the neutral Higgsino of the mass below 190 GeV, which can be dark matter of the universe. The mass of the lighter top squark can be smaller than 300 GeV, which may be relevant for Run II at the Tevatron.