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Register a new userSFitter: Reconstructing the MSSM Lagrangian from LHC data
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Once supersymmetry is found at the LHC, the question arises what are the fundamental parameters of the Lagrangian. The answer to this question should thereby not be biased by assumptions on high-scale models. SFitter is a tool designed for this task. Taking LHC (and possibly ILC) data as input it scans the TeV-scale MSSM parameter space using its new weighted Markov chain technique. Using this scan it determines a list of best-fitting parameter points. Additionally a log-likelihood map is calculated, which can be reduced to lower-dimensional Frequentists profile likelihoods or Bayesian probability maps.
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SFITTER is a new analysis tool to determine supersymmetric model parameters from collider measurements. Using the set of supersymmetric mass measurements at the LC and at the LHC we show how both colliders probe different sectors of the MSSM Lagrangian. This observation is a strong motivation to move from a parameter fit assuming a certain model to the unconstrained weak-scale MSSM Lagrangian. We argue how the technical challenges can be dealt with in a combined fit/grid approach with full correlations.
ATLAS and CMS collaborations have reported the results on the Higgs search analyzing $sim 36$ fb$^{-1}$ data from Run-II of LHC at 13 TeV. In this work, we study the Higgs sector of the phenomenological Minimal Supersymmetric Standard Model, in light of the recent Higgs data, by studying separately the impact of Run-I and Run-II data. One of the major impacts of the new data on the parameter space comes from the direct searches of neutral CP-even and CP-odd heavy Higgses ($H$ and $A$, respectively) in the $H/A to tau^{+} tau^{-}$ channel which disfavours high $tanbeta$ regions more efficiently than Run-I data. Secondly, we show that the latest result of the rare radiative decay of $B$ meson imposes a slightly stronger constraint on low $tan beta$ and low $M_A$ region of the parameter space, as compared to its previous measurement. Further, we find that in a global fit Run-II light Higgs signal strength data is almost comparable in strength with the corresponding Run-I data. Finally, we discuss scenarios with the Heavy Higgs boson decaying into electroweakinos and third generation squarks and sleptons.
In this analysis we explore the phenomenological constraints of models with non-holomorphic soft SUSY breaking terms in a beyond the MSSM scenario having identical particle content. The model referred as NHSSM shows various promising features like the possibility of a strong reduction in electroweak fine-tuning even for a scenario of a heavy higgsino type of LSP, a fact that is unavailable in pMSSM models. The other important aspect is satisfying the muon $g-2$ data even for a small $tanbeta$ via a small value of coupling $A_mu$ associated with the tri-linear non-holomorphic soft term. Thus, a large SUSY contribution to muon $g-2$ is possible even for a significantly large smuon mass $m_{tilde {mu_1}}$. The Higgs mass radiative corrections are contributed by both the holomorphic and non-holomorphic trilinear soft parameters $A_t$ and $A_t$, thus diluting the requirement to have a larger $A_t$ to satisfy the Higgs mass data. The model also provides with valid parameter space satisfying the constraint of $B rightarrow X_s +gamma$ for large values of $tanbeta$, a scenario unfavourable in pMSSM.
We describe a likelihood analysis using MasterCode of variants of the MSSM in which the soft supersymmetry-breaking parameters are assumed to have universal values at some scale $M_{in}$ below the supersymmetric grand unification scale $M_{GUT}$, as can occur in mirage mediation and other models. In addition to $M_{in}$, such `sub-GUT models have the 4 parameters of the CMSSM, namely a common gaugino mass $m_{1/2}$, a common soft supersymmetry-breaking scalar mass $m_0$, a common trilinear mixing parameter $A$ and the ratio of MSSM Higgs vevs $tanbeta$, assuming that the Higgs mixing parameter $mu > 0$. We take into account constraints on strongly- and electroweakly-interacting sparticles from $sim 36$/fb of LHC data at 13 TeV and the LUX and 2017 PICO, XENON1T and PandaX-II searches for dark matter scattering, in addition to the previous LHC and dark matter constraints as well as full sets of flavour and electroweak constraints. We find a preference for $M_{in} sim 10^5$ to $10^9$ GeV, with $M_{in} sim M_{GUT}$ disfavoured by $Delta chi^2 sim 3$ due to the ${rm BR}(B_{s, d} to mu^+mu^-)$ constraint. The lower limits on strongly-interacting sparticles are largely determined by LHC searches, and similar to those in the CMSSM. We find a preference for the LSP to be a Bino or Higgsino with $tilde{chi^0_1} sim 1$ TeV, with annihilation via heavy Higgs bosons $H/A$ and stop coannihilation, or chargino coannihilation, bringing the cold dark matter density into the cosmological range. We find that spin-independent dark matter scattering is likely to be within reach of the planned LUX-Zeplin and XENONnT experiments. We probe the impact of the $(g-2)_mu$ constraint, finding similar results whether or not it is included.
We interpret within the phenomenological MSSM (pMSSM) the results of SUSY searches published by the CMS collaboration based on the first ~1 fb^-1 of data taken during the 2011 LHC run at 7 TeV. The pMSSM is a 19-dimensional parametrization of the MSSM that captures most of its phenomenological features. It encompasses, and goes beyond, a broad range of more constrained SUSY models. Performing a global Bayesian analysis, we obtain posterior probability densities of parameters, masses and derived observables. In contrast to constraints derived for particular SUSY breaking schemes, such as the CMSSM, our results provide more generic conclusions on how the current data constrain the MSSM.
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