Search

We revisit the calculation of the electron, neutron, and proton electric dipole moments (EDMs) in the constrained minimal supersymmetric standard model (CMSSM). The relatively large mass of the Higgs boson, mH ≃ 125 GeV coupled with the (as yet) lack of discovery of any supersymmetric particle at the LHC, has pushed the supersymmetry breaking scale to several TeV or higher. Though one might expect this decoupling to have relaxed completely any bounds on the two CP violating phases in the CMSSM (θμ and θA), the impressive experimental improvements in the limits on the EDMs (particularly the electron EDM) still allow us to set constraints of order (0.01−0.1)π on θA and (0.001−0.1)π on θμ. We also discuss the impact of future improvements in the experimental limits on supersymmetric models. [ABSTRACT FROM AUTHOR]

We revisit the viability of the CMSSM, searching for regions of parameter space that yield a neutralino dark matter density compatible with Planck measurements, as well as LHC constraints including sparticle searches and the mass of the Higgs boson, recent direct limits on spin-independent and -dependent dark matter scattering from the LUX-ZEPLIN (LZ) experiment, the indirect constraints from Fermi-LAT and H.E.S.S. on dark matter annihilations to photons in dwarf spheroidal galaxies and the Galactic Centre, and the IceCube limits on muons from annihilations to neutrinos in the Sun. For representative values of tan β and A 0 we map in detail the Planck-compatible strips in CMSSM parameter planes, which exhibit multiple distinctive features for large tan β , A 0 = 0 and μ > 0 , and identify portions of the strips that survive all the phenomenological constraints. We find that the most powerful constraint is that from m h , followed by the LZ limit on spin-independent scattering, whereas sparticle searches at the LHC and indirect dark matter searches are less restrictive. Most of the surviving CMSSM parameter space features a Higgsino-like dark matter particle with a mass ∼ 1000 - 1100 GeV, which could best be probed with future direct searches for dark matter scattering. [ABSTRACT FROM AUTHOR]

We consider proton decay and g μ - 2 in flipped SU(5) GUT models. We first study scenarios in which the soft supersymmetry-breaking parameters are constrained to be universal at some high scale M in above the standard GUT scale where the QCD and electroweak SU(2) couplings unify. In this case the proton lifetime is typically ≳ 10 36 years, too long to be detected in the foreseeable future, and the supersymmetric contribution to g μ - 2 is too small to contribute significantly to resolving the discrepancy between the experimental measurement and data-driven calculations within the Standard Model. However, we identify a region of the constrained flipped SU(5) parameter space with large couplings between the 10- and 5-dimensional GUT Higgs representations where p → e + π 0 decay may be detectable in the Hyper-Kamiokande experiment now under construction, though the contribution to g μ - 2 is still small. A substantial contribution to g μ - 2 is possible, however, if the universality constraints on the soft supersymmetry-breaking masses are relaxed. We find a 'quadrifecta' region where observable proton decay co-exists with a (partial) supersymmetric resolution of the g μ - 2 discrepancy and acceptable values of m h and the relic LSP density. [ABSTRACT FROM AUTHOR]

Successful models of pure gravity mediation (PGM) with radiative electroweak symmetry breaking can be expressed with as few as two free parameters, which can be taken as the gravitino mass and $$\tan \beta $$ . These models easily support a 125-126 GeV Higgs mass at the expense of a scalar spectrum in the multi-TeV range and a much lighter wino as the lightest supersymmetric particle. In these models, it is also quite generic that the Higgs mixing mass parameter, $$\mu $$ , which is determined by the minimization of the Higgs potential is also in the multi-TeV range. For $$\mu >0$$ , the thermal relic density of winos is too small to account for the dark matter. The same is true for $$\mu <0$$ unless the gravitino mass is of order 500 TeV. Here, we consider the origin of a multi-TeV $$\mu $$ parameter arising from the breakdown of a Peccei-Quinn (PQ) symmetry. A coupling of the PQ-symmetry breaking field, $$P$$ , to the MSSM Higgs doublets, naturally leads to a value of $$\mu \sim \langle P \rangle ^2 /M_P \sim {\mathcal O}(100)$$ TeV and of the order that is required in PGM models. In this case, axions make up the dark matter or some fraction of the dark matter with the remainder made up from thermal or non-thermal winos. We also provide solutions to the problem of isocurvature fluctuations with axion dark matter in this context. [ABSTRACT FROM AUTHOR]

The simplest model of pure gravity mediation contains only two free parameters: the gravitino mass and tan β. Scalar masses are universal at some high energy renormalization scale and gaugino masses are determined through anomalies and depend on the gravitino mass and the gauge couplings. This theory requires a relatively large gravitino mass ( m3/2≳300 TeV) and a limited range in tan β≃1.7–2.5. Here we generalize the theory to allow for non-universality in the Higgs soft masses. This introduces zero, one or two new free parameters associated with Higgs soft masses. This generalization allows us to greatly increase the allowed range in tan β and it allows one to find viable solutions with lower m3/2. The latter is important if we hope to find a low energy signal from gluinos. Some special cases of these non-universalities are suggestive of Higgs bosons as Nambu–Goldstone bosons or a partial no-scale structure for the Higgs doublets. Thus, we probe signatures at the weak scale and structures at the GUT and/or Planck scale. [ABSTRACT FROM AUTHOR]

The apparent discovery of a Higgs boson with mass ∼125 GeV has had a significant impact on the constrained minimal supersymmetric extension of the Standard Model (the CMSSM). Much of the low-mass parameter space in the CMSSM has been excluded by supersymmetric particle searches at the LHC as well as by the Higgs mass measurement and the emergent signal for B→ μ μ. Here, we consider the impact of these recent LHC results on several variants of the CMSSM with a primary focus on obtaining a Higgs mass of ∼125 GeV. In particular, we consider the one- and two-parameter extensions of the CMSSM with one or both of the Higgs masses set independently of the common sfermion mass, m (the NUHM1,2). We also consider the one-parameter extension of the CMSSM in which the input universality scale M is below the GUT scale (the sub-GUT CMSSM). Finally, we reconsider mSUGRA models with sub-GUT universality, which have the same number of parameters as the CMSSM. We find that when M< M large regions of parameter space open up where the relic density of neutralinos can successfully account for dark matter with a Higgs boson mass ∼125 GeV. Interestingly, we find that the preferred range of the A-term in sub-GUT mSUGRA models straddles that predicted by the simplest Polonyi model. [ABSTRACT FROM AUTHOR]

We describe the resulting phenomenology of string theory/supergravity models with strong moduli stabilization. The KL model with F-term uplifting, is one such example. Models of this type predict universal scalar masses equal to the gravitino mass. In contrast, A-terms receive highly suppressed gravity mediated contributions. Under certain conditions, the same conclusion is valid for gaugino masses, which like A-terms, are then determined by anomalies. In such models, we are forced to relatively large gravitino masses (30-1000 TeV). We compute the low-energy spectrum as a function of m. We see that the Higgs masses naturally takes values between 125-130 GeV. The lower limit is obtained from the requirement of chargino masses greater than 104 GeV, while the upper limit is determined by the relic density of dark matter (wino-like). [ABSTRACT FROM AUTHOR]

While the constrained minimal supersymmetric standard model (CMSSM) with universal gaugino masses, m, scalar masses, m, and A-terms, A, defined at some high energy scale (usually taken to be the GUT scale) is motivated by general features of supergravity models, it does not carry all of the constraints imposed by minimal supergravity (mSUGRA). In particular, the CMSSM does not impose a relation between the trilinear and bilinear soft supersymmetry breaking terms, B= A− m, nor does it impose the relation between the soft scalar masses and the gravitino mass, m= m. As a consequence, tan β is computed given values of the other CMSSM input parameters. By considering a Giudice-Masiero (GM) extension to mSUGRA, one can introduce new parameters to the Kähler potential which are associated with the Higgs sector and recover many of the standard CMSSM predictions. However, depending on the value of A, one may have a gravitino or a neutralino dark matter candidate. We also consider the consequences of imposing the universality conditions above the GUT scale. This GM extension provides a natural UV completion for the CMSSM. [ABSTRACT FROM AUTHOR]

Taking into account the available accelerator and astrophysical constraints, the mass of the lightest neutral Higgs boson h in the minimal supersymmetric extension of the Standard Model with universal soft supersymmetry-breaking masses (CMSSM) has been estimated to lie between 114 and ~130 GeV. Recent data from ATLAS and CMS hint that mh ~ 125 GeV, though mh ~ 119 GeV may still be a possibility. Here we study the consequences for the parameters of the CMSSM and direct dark matter detection if the Higgs hint is confirmed, focusing on the strips in the (m1/2,m0) planes for different tan β and A0 where the relic density of the lightest neutralino ? falls within the range of the cosmological cold dark matter density allowed by WMAP and other experiments. We find that if mh ~ 125 GeV focus-point strips would be disfavoured, as would the low-tan β ῖ-? and t~1-? coannihilation strips, whereas the ῖ-? coannihilation strip at large tan β and A0 > 0 would be favoured, together with its extension to a funnel where rapid annihilation via direct-channel H/A poles dominates. On the other hand, if mh ~ 119 GeV more options would be open. We give parameterisations of WMAP strips with large tan β and fixed A0/m0 > 0 that include portions compatible with mh = 125 GeV, and present predictions for spin-independent elastic dark matter scattering along these strips. These are generally low for models compatible with mh = 125 GeV, whereas the XENON100 experiment already excludes some portions of strips where mh is smaller. [ABSTRACT FROM AUTHOR]

In the context of phenomenological models in which the soft supersymmetry-breaking parameters of the MSSM become universal at some unification scale, M, above the GUT scale, M, it is possible that all the scalar mass parameters m, the trilinear couplings A and the bilinear Higgs coupling B vanish simultaneously, as in no-scale supergravity. Using these no-scale inputs in a renormalisation-group analysis of the minimal supersymmetric SU(5) GUT model, we pay careful attention to the matching of parameters at the GUT scale. We delineate the region of M, m and tan β where the resurrection of no-scale supergravity is possible, taking due account of the relevant phenomenological constraints such as electroweak symmetry breaking, m, b→ s γ, the neutralino cold dark matter density Ω h and g−2. No-scale supergravity survives in an L-shaped strip of parameter space, with one side having m≳200 GeV, the second (orthogonal) side having M≳5×10 GeV. Depending on the relative signs and magnitudes of the GUT superpotential couplings, these may be connected to form a triangle whose third side is a hypotenuse at larger M, m and tan β, whose presence and location depend on the GUT superpotential parameters. We compare the prospects for detecting sparticles at the LHC in no-scale supergravity with those in the CMSSM and the NUHM. [ABSTRACT FROM AUTHOR]

Without assuming that Higgs masses have the same values as other scalar masses at the input GUT scale, we combine constraints on the minimal supersymmetric extension of the Standard Model (MSSM) coming from the cold dark matter density with the limits from direct searches at accelerators such as LEP, indirect measurements such as b→sγ decay and the anomalous magnetic moment of the muon. The requirement that Higgs masses-squared be positive at the GUT scale imposes important restrictions on the MSSM parameter space, as does the requirement that the LSP be neutral. We analyze the interplay of these constraints in the (μ,mA), (μ,m1/2), (m1/2,m0) and (mA,tanβ) planes. These exhibit new features not seen in the corresponding planes in the constrained MSSM in which universality is extended to Higgs masses. [Copyright &y& Elsevier]

Stop coannihilation may bring the relic density of heavy supersymmetric dark matter particles into the range allowed by cosmology. The efficiency of this process is enhanced by stop-antistop annihilations into the longitudinal (Goldstone) modes of the W and Z bosons, as well as by Sommerfeld enhancement of stop annihilations and the effects of bound states. Since the couplings of the stops to the Goldstone modes are proportional to the trilinear soft supersymmetry-breaking A-terms, these annihilations are enhanced when the A-terms are large. However, the Higgs mass may be reduced below the measured value if the A-terms are too large. Unfortunately, the interpretation of this constraint on the stop coannihilation strip is clouded by differences between the available Higgs mass calculators. For our study, we use as our default calculator FeynHiggs 2.13.0, the most recent publicly available version of this code. Exploring the CMSSM parameter space, we find that along the stop coannihilation strip the masses of the stops are severely split by the large A-terms. This suppresses the Higgs mass drastically for μ and A0>0, whilst the extent of the stop coannihilation strip is limited for A0<0 and either sign of μ. However, in sub-GUT models, reduced renormalization-group running mitigates the effect of the large A-terms, allowing larger LSP masses to be consistent with the Higgs mass calculation. We give examples where the dark matter particle mass may reach ≳8 TeV. [ABSTRACT FROM AUTHOR]

In this article, we demonstrate that the inclusion of right-handed neutrino superfields in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) makes it possible to impose universality conditions on the soft supersymmetry-breaking parameters at the Grand Unification scale, alleviating many of the problems of the so-called Constrained NMSSM. We have studied the renormalization group equations of this model, showing that right-handed neutrinos greatly contribute to driving the singlet Higgs mass-squared parameter negative, which makes it considerably easier to satisfy the conditions for radiative electroweak symmetry breaking. The new fields also lead to larger values of the Standard Model Higgs mass, thus making it easier to reproduce the measured value. As a consequence, all bounds from colliders and low-energy observables can be fulfilled in wide areas of the parameter space. However, the relic density in these regions is generally too high requiring some form of late entropy production to dilute the density of the lightest supersymmetric particle. [ABSTRACT FROM AUTHOR]

Abstract: We estimate the mass of the lightest neutral Higgs boson h in the minimal supersymmetric extension of the Standard Model with universal soft supersymmetry-breaking masses (CMSSM), subject to the available accelerator and astrophysical constraints. For , we find that and a peak in the distribution ≃55. We observe two distinct peaks in the distribution of values, corresponding to two different regions of the CMSSM parameter space. Values of correspond to small values of the gaugino mass and the soft trilinear supersymmetry-breaking parameter , lying along coannihilation strips, and most of the allowed parameter sets are consistent with a supersymmetric interpretation of the possibly discrepancy in . On the other hand, values of may correspond to much larger values of and , lying in rapid-annihilation funnels. The favoured ranges of vary with , the two peaks being more clearly separated for and merging for . If the constraint is imposed, the mode of the distribution is quite stable, being for all the studied values of . [Copyright &y& Elsevier]

We explore the parameter space of the minimal supersymmetric extension of the Standard Model (MSSM), allowing the soft supersymmetry-breaking masses of the Higgs multiplets, m1,2, to be non-universal (NUHM). Compared with the constrained MSSM (CMSSM) in which m1,2 are required to be equal to the soft supersymmetry-breaking masses m0 of the squark and slepton masses, the Higgs mixing parameter μ and the pseudoscalar Higgs mass mA, which are calculated in the CMSSM, are free in the NUHM model. We incorporate accelerator and dark matter constraints in determining allowed regions of the (μ,mA), (μ,M2) and (m1/2,m0) planes for selected choices of the other NUHM parameters. In the examples studied, we find that the LSP mass cannot be reduced far below its limit in the CMSSM, whereas mA may be as small as allowed by LEP for large tanβ. We present in details of the calculations of neutralino–slepton, chargino–slepton and neutralino–sneutrino coannihilation needed in our exploration of the NUHM. [Copyright &y& Elsevier]