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Peter Athron
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We present comprehensive global fits of supersymmetric (SUSY) models from the Global and Modular Beyond-the-Standard-Model Inference Tool (GAMBIT) collaboration, based on arXiv:1705.07935 and arXiv:1705.07917. We investigate several variants of the minimal supersymmetric standard model, a fully constrained version (CMSSM) with universal scalar ($m_0$), gaugino ($m_{1/2}$) and trilinear masses ($A_0$) at the gauge coupling unification scale, a similar model that is relaxed by adding an extra parameter for the soft Higgs masses (NUHM1), another where the soft Higgs masses are also split (NUHM2) and finally a weak scale MSSM7 model. We use the public GAMBIT global fitting framework and take into account all relevant data to reveal the regions of parameter space with the highest likelihood. Our results reveal that all models have very heavy scenarios that are well out of reach of the LHC, but will be probed by forthcoming dark matter experiments, as well as a stop-co-annihilation region which has better prospects for detection in collider experiments. The stau co-annihilation region is excluded from the CMSSM at $2 sigma$ but is present in the NUHM1 and NUHM2 variants. Finally by relaxing constraints in the NUHM1, NUHM2 and MSSM7 we see additional regions appear: lighter chargino co-annihilation region, sbottom co-annihilation and $h/Z$ funnels.
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We present the most comprehensive global fits to date of three supersymmetric models motivated by grand unification: the Constrained Minimal Supersymmetric Standard Model (CMSSM), and its Non-Universal Higgs Mass generalisations NUHM1 and NUHM2. We include likelihoods from a number of direct and indirect dark matter searches, a large collection of electroweak precision and flavour observables, direct searches for supersymmetry at LEP and Runs I and II of the LHC, and constraints from Higgs observables. Our analysis improves on existing results not only in terms of the number of included observables, but also in the level of detail with which we treat them, our sampling techniques for scanning the parameter space, and our treatment of nuisance parameters. We show that stau co-annihilation is now ruled out in the CMSSM at more than 95% confidence. Stop co-annihilation turns out to be one of the most promising mechanisms for achieving an appropriate relic density of dark matter in all three models, whilst avoiding all other constraints. We find high-likelihood regions of parameter space featuring light stops and charginos, making them potentially detectable in the near future at the LHC. We also show that tonne-scale direct detection will play a largely complementary role, probing large parts of the remaining viable parameter space, including essentially all models with multi-TeV neutralinos.
We review the MasterCode fits of several incarnations of the Minimal Supersymmetric Standard Model (MSSM). These include the GUT models based on mAMSB and SU(5), sub-GUT models as well as a model defined at low energies with 11 free parameters, the pMSSM11. The fit combines consistently measurements of Higgs boson properties, searches for additional Higgs bosons and supersymmetric (SUSY) particles, low-energy and flavor experiments as well as Dark Matter (DM) measurements. We predict the preferred SUSY mass spectra in these models and analyze the discovery potential of future e+e- colliders such as the ILC and CLIC.
We consider a simple extension of the electroweak theory, incorporating one $SU(2)_L$ doublet of colour-octet scalars with Yukawa couplings satisfying the principle of minimal flavour violation. Using the HEPfit package, we perform a global fit to the available data, including all relevant theoretical constraints, and extract the current bounds on the model parameters. Coloured scalars with masses below 1.05 TeV are already excluded, provided they are not fermiophobic. The mass splittings among the different (charged and CP-even and CP-odd neutral) scalars are restricted to be smaller than 20 GeV. Moreover, for scalar masses smaller than 1.5 TeV, the Yukawa coupling of the coloured scalar multiplet to the top quark cannot exceed the one of the SM Higgs doublet by more than 80%. These conclusions are quite generic and apply in more general frameworks (without fine tunings). The theoretical requirements of perturbative unitarity and vacuum stability enforce relevant constraints on the quartic scalar potential parameters that are not yet experimentally tested.
The strong coupling constant $alpha_s$ and the heavy-quark masses, $m_c$, $m_b$, $m_t$ are extracted simultaneosly with the parton distribution functions (PDFs) in the updated ABM12 fit including recent data from CERN-SPS, HERA, Tevatron, and the LHC. The values of begin{eqnarray} onumber alpha_s(M_Z)&=&0.1147pm0.0008~({rm exp.)}, onumber m_c(m_c)&=&1.252pm 0.018~({rm exp.})~{rm GeV}, onumber m_b(m_b)&=&3.83pm0.12~({rm exp.})~{rm GeV}, onumber m_t(m_t)&=&160.9pm1.1~({rm exp.})~{rm GeV} end{eqnarray} are obtained with the $overline{MS}$ heavy-quark mass definition being employed throughout the analysis.
In theories with Universal Extra-Dimensions (UED), the gamma_1 particle, first excited state of the hypercharge gauge boson, provides an excellent Dark Matter (DM) candidate. Here we use a modified version of the SuperBayeS code to perform a Bayesian analysis of the minimal UED scenario, in order to assess its detectability at accelerators and with DM experiments. We derive in particular the most probable range of mass and scattering cross sections off nucleons, keeping into account cosmological and electroweak precision constraints. The consequences for the detectability of the gamma_1 with direct and indirect experiments are dramatic. The spin-independent cross section probability distribution peaks at ~ 10^{-11} pb, i.e. below the sensitivity of ton-scale experiments. The spin-dependent cross-section drives the predicted neutrino flux from the center of the Sun below the reach of present and upcoming experiments. The only strategy that remains open appears to be direct detection with ton-scale experiments sensitive to spin-dependent cross-sections. On the other hand, the LHC with 1 1/fb of data should be able to probe the current best-fit UED parameters.
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