MSSM Parameter Space Research Articles

MSSM at future Higgs factories * *HL was Supported by the National Natural Science Foundation of China (NNSFC) (11635009) and Natural Science Foundation of Shandong Province (ZR2017JL006). HS and SS are Supported in part by the Department of Energy (DE-FG02-13ER41976/DE-SC0009913). WS is Supported by the Australian Research Council (ARC) Centre of Excellence for Dark Matter Particle Physics (CE200100008). JMY was

In this work, we study the implications of Higgs precision measurements at future Higgs factories for the MSSM parameter space, focusing on the dominant stop sector contributions. We perform a multi-variable fit to both the signal strength for various Higgs decay channels at Higgs factories and the Higgs mass. The χ 2 fit results show sensitivity to mA , tan β, stop mass parameter m SUSY , and the stop left-right mixing parameter Xt. We also study the impact of the Higgs mass prediction on the MSSM and compare the sensitivities of different Higgs factories.

Possibility of Observing Charged Higgs in the Single Top Production Channel at LHC

Single top quark production through weak interactions is an important source of charged Higgs in the Minimal Super Symmetric Standard Model. In the s-channel single top production ,charged Higgs having largest cross-section may appear as a propagator in the form of heavy resonance state decaying to a pair of top and bottom quark. In this paper the channel under consideration is $pp \rightarrow H^{\pm}\rightarrow tb \rightarrow b\bar{b}W^{\pm} \rightarrow b\bar{b}\tau^{\pm} \nu_{\tau}$, where top quark exclusively decays into a pair of b quark and W boson while W boson subsequently decays to $\tau$ jet and neutrino. So the final state is characterized by the presence of two b jets, hadronic $\tau$ decay and missing transverse energy.It has been demonstrated that the charged Higgs signal observability is possible within the available MSSM parameter space (tan$\beta$, $m_{H^{\pm}})$ respecting all experimental and theoretical constraints due to presence of QCD multijet and electroweak background events at LHC. In order to show the observability potential of charged Higgs, the charged Higgs signal are well observed or excluded in a wide range of phase space particular ($\beta > 35$ at 500 $fb^{-1}$ , $\beta > 25$ at 1000 $fb^{-1}$ , $\beta > 15$ at 3000 $fb^{-1}$ ) at $\sqrt{s}=$14 TeV.

Perspectives of double beta and dark matter search as windows to new physics

Nuclear double beta decay provides an extraordinarily broad potential to search for beyond Standard Model physics, probing already now the TeV scale, on which new physics should manifest itself. These possibilities are reviewed here. First, the results of present generation experiments are presented. The most sensitive one of them - the Heidelberg-Moscow experiment in the Gran Sasso - probes the electron mass now in the sub eV region and has reached recently a limit of ~ 0.1 eV. This limit has striking influence on presently discussed neutrino mass scenarios. Basing to a large extent on the theoretical work of the Heidelberg Double Beta Group in the last two years, results are obtained also for SUSY models (R-parity breaking, sneutrino mass), leptoquarks (leptoquark-Higgs coupling), compositeness, right-handed W boson mass, test of special relativity and equivalence principle in the neutrino sector and others. These results are comfortably competitive to corresponding results from high-energy accelerators like TEVATRON, HERA, etc. One of the enriched 7Ge detectors also yields the most stringent limits for cold dark matter (WIMPs) to date by using raw data. Second, future perspectives of ßß research are discussed. A new Heidelberg experimental proposal (GENIUS) will allow to increase the sensitivity for Majorana neutrino masses from the present level of at best 0.1 eV down to 0.01 or even 0.001 eV. Its physical potential would be a breakthrough into the multi-TeV range for many beyond standard models. Its sensitivity for neutrino oscillation parameters would be larger than of all present terrestrial neutrino oscillation experiments and of those planned for the future. It could probe directly the large angle, and for almost degenerate neutrino mass scenarios even the small angle solution of the solar neutrino problem. It would further, already in a first step using only 100 kg of natural Ge detectors, cover almost the full MSSM parameter space for prediction of neutralinos as cold dark matter, making the experiment competitive to LHC in the search for supersymmetry. Finally GENIUS could be used as the first real time detector of solar pp neutrinos.

Realistic simplified gaugino-higgsino models in the MSSM

We present simplified MSSM models for light neutralinos and charginos with realistic mass spectra and realistic gaugino-higgsino mixing, that can be used in experimental searches at the LHC. The formerly used naive approach of defining mass spectra and mixing matrix elements manually and independently of each other does not yield genuine MSSM benchmarks. We suggest the use of less simplified, but realistic MSSM models, whose mass spectra and mixing matrix elements are the result of a proper matrix diagonalisation. We propose a novel strategy targeting the design of such benchmark scenarios, accounting for user-defined constraints in terms of masses and particle mixing. We apply it to the higgsino case and implement a scan in the four relevant underlying parameters {mu , tan beta , M_{1}, M_{2}} for a given set of light neutralino and chargino masses. We define a measure for the quality of the obtained benchmarks, that also includes criteria to assess the higgsino content of the resulting charginos and neutralinos. We finally discuss the distribution of the resulting models in the MSSM parameter space as well as their implications for supersymmetric dark matter phenomenology.

Heavy supersymmetry with m h = 125 GeV in the effective field theory approach

After the Higgs boson discovery at the LHC with the mass 125 GeV a number of MSSM scenarios has been proposed to separate suitable domains of the parameter space. In the framework of two scenarios we demostrate possible reduction of multidimentional MSSM parameter space and analyse precise restrictions imposed on it.

Deciphering the MSSM Higgs mass at future hadron colliders

Future hadron colliders will have a remarkable capacity to discover massive new particles, but their capabilities for precision measurements of couplings that can reveal underlying mechanisms have received less study. In this work we study the capability of future hadron colliders to shed light on a precise, focused question: is the higgs mass of 125 GeV explained by the MSSM? If supersymmetry is realized near the TeV scale, a future hadron collider could produce huge numbers of gluinos and electroweakinos. We explore whether precision measurements of their properties could allow inference of the scalar masses and tan β with sufficient accuracy to test whether physics beyond the MSSM is needed to explain the higgs mass. We also discuss dark matter direct detection and precision higgs physics as complementary probes of tan β. For concreteness, we focus on the mini-split regime of MSSM parameter space at a 100 TeV pp collider, with scalar masses ranging from 10s to about 1000 TeV.

The s-channel charged Higgs in the fully hadronic final state at LHC

With the current measurements performed by CMS and ATLAS experiments, the light charged Higgs scenario ($m_{H^{\pm}}$ $<$ 160 GeV), is excluded for most of the parameter space in the context of MSSM. However, there is still possibility to look for heavy charged Higgs boson particularly in the $s$-channel single top production process where the charged Higgs may appear as a heavy resonance state and decay to $t\bar{b}$. The production process under consideration in this paper is $pp \ra H^{\pm} \ra t\bar{b}~+~h.c.$, where the top quark decays to $W^{+}b$ and $W^{+}$ boson subsequently decays to two light jets. It is shown that despite the presence of large QCD and electroweak background events, the charged Higgs signal can be extracted and observed at a large area of MSSM parameter space ($m_{H^{\pm}}$,tan$\beta$) at LHC. The observability of charged Higgs is potentially demonstrated with 5$\sigma$ contours and $95\%$ confidence level exclusion curves at different integrated LHC luminosities assuming a nominal center of mass energy of $\sqrt{s}$ = 14 TeV.

Sommerfeld enhancements and relic abundance of neutralino dark matter in the general MSSM

We discuss the calculation of Sommerfeld enhancements on the neutralino LSP relic abundance calculation for heavy neutralino dark matter including co-annihilations of nearly mass-degenerate neutralino and chargino states. A newly developed EFT framework enables us to consider for the first time all (off)-diagonal potential and annihilation matrices including P- and next-to-next-to-leading order S-wave effects for a generic MSSM parameter space point, and to treat effects from heavy states perturbatively.

Post-Higgs THDM scenarios associated with the new diphoton resonance data

The CP -even and CP -odd scalar states of the two-Higgs-doublet model (THDM) and the Higgs sector of theMinimal Supersymmetric StandardModel (MSSM), with properties which could lead to the 750 GeV excess in the γγ invariant mass distribution, are studied. It is shown that THDM and MSSM are viable in explaining the observed excess without additional assumptions only when the alignment and decoupling limits break down. If the origin of the excess is not in a Higgs sector, regions of the MSSM parameter space are separated where the lightest CP -even Higgs boson is identical to the Standard Model scalar.

Supersymmetric dark matter after LHC run 1.

Different mechanisms operate in various regions of the MSSM parameter space to bring the relic density of the lightest neutralino, tilde{chi }^0_{1}, assumed here to be the lightest SUSY particle (LSP) and thus the dark matter (DM) particle, into the range allowed by astrophysics and cosmology. These mechanisms include coannihilation with some nearly degenerate next-to-lightest supersymmetric particle such as the lighter stau tilde{tau }_{1}, stop tilde{t}_{1} or chargino tilde{chi }^pm _{1}, resonant annihilation via direct-channel heavy Higgs bosons H / A, the light Higgs boson h or the Z boson, and enhanced annihilation via a larger Higgsino component of the LSP in the focus-point region. These mechanisms typically select lower-dimensional subspaces in MSSM scenarios such as the CMSSM, NUHM1, NUHM2, and pMSSM10. We analyze how future LHC and direct DM searches can complement each other in the exploration of the different DM mechanisms within these scenarios. We find that the {tilde{tau }_1} coannihilation regions of the CMSSM, NUHM1, NUHM2 can largely be explored at the LHC via searches for / !!!! E_T events and long-lived charged particles, whereas their H / A funnel, focus-point and tilde{chi }^pm _{1} coannihilation regions can largely be explored by the LZ and Darwin DM direct detection experiments. We find that the dominant DM mechanism in our pMSSM10 analysis is tilde{chi }^pm _{1} coannihilation: parts of its parameter space can be explored by the LHC, and a larger portion by future direct DM searches.

Threshold corrections to the bottom quark mass revisited

Threshold corrections to the bottom quark mass are often estimated under the approximation that tan β enhanced contributions are the most dominant. In this work we revisit this common approximation made to the estimation of the supersymmetric thresh-old corrections to the bottom quark mass. We calculate the full one-loop supersymmetric corrections to the bottom quark mass and survey a large part of the phenomenological MSSM parameter space to study the validity of considering only the tan β enhanced corrections. Our analysis demonstrates that this approximation underestimates the size of the threshold corrections by ∼ 12.5% for most of the considered parameter space. We discuss the consequences for fitting the bottom quark mass and for the effective couplings to Higgses. We find that it is important to consider the additional contributions when fitting the bottom quark mass but the modifications to the effective Higgs couplings are typically $$ \mathcal{O} $$ (few)% for the majority of the parameter space considered.

MSSM dark matter and a light slepton sector: The incredible bulk

Recent experimental results from the LHC have placed strong constraints on the masses of QCD-charged superpartners. The MSSM parameter space is also constrained by the measurement of the Higgs boson mass, and the requirement that the relic density of lightest neutralinos be consistent with observations. Although large regions of the MSSM parameter space can be excluded by these combined bounds, leptophilic versions of the MSSM can survive these constraints. In this paper we consider a scenario in which the requirements of minimal flavor violation, vanishing $CP$-violation, and mass universality are relaxed, specifically focusing on scenarios with light sleptons. We find a large region of parameter space, analogous to the original bulk region, for which the lightest neutralino is a thermal relic with an abundance consistent with that of dark matter. We find that these leptophilic models are constrained by measurements of the magnetic and electric dipole moments of the electron and muon, and that these models have interesting signatures at a variety of indirect detection experiments.

Exploring MSSM for charge and color breaking and other constraints in the context of Higgs@125 GeV

Exploring MSSM parameter space after the discovery of Higgs Boson with mass 125 GeV naturally demands large top-squark mixing or large trilinear coupling parameter $A_t$ in particular, so as to avoid excessively heavy squark, specially for the universal models like CMSSM. We study stability of electroweak symmetry breaking vacua in possible presence of deeper charge-color symmetry breaking minima within MSSM. Besides stable vacua, we consider scenarios characterized by the presence of global CCB minima, with SM like charge and color conserving vacuum, having stability over cosmologically large lifetime {(\it long-lived states)}. We allow vacuum expectation values for both stop as well as sbottom fields, since these belong to the third generation of sfermions with larger Yukawa couplings that have immediate effect on the tunneling time. Moreover, for large $\mu$ regions, radiative corrections to Higgs boson mass from bottom-squark loop is quite significant. Regions of MSSM parameters space become viable for large $A_t$ and large $\mu$ zones which are generically excluded via the traditional analytical CCB constraints. For a large value of $\tan\beta$, safe vacua associated with large values of $|\mu|$ and $|A_t|$ are predominantly long-lived and may be associated with relatively light stop masses. We also identify low $\mu$ regions associated with long-lived states. Both the above zones can be friendly to muon $g-2$ constraint. We also impose constraints from ${\rm Br}(B \rightarrow X_s \gamma)$ and ${\rm Br}(B_s \rightarrow \mu^+ \mu^-)$. We do the analysis for a moderate and a large $\tan\beta$. Results are compatible with dark matter related constraints, as expected.

Understanding the correlation between (g − 2) μ and μ → eγ in the MSSM

The supersymmetric contributions to the muon anomalous magnetic moment $a_\mu$ and to the decay $\mu\to e\gamma$ are given by very similar Feynman diagrams. Previous works reported correlations in specific scenarios, in particular if $a_\mu$ is dominated by a single diagram. In this work we give an extensive survey of the possible correlations. We discuss examples of single-diagram domination with particularly strong correlations, and provide corresponding benchmark parameter points. We show how the correlations are weakened by significant cancellations between diagrams in large parts of the MSSM parameter space. Nevertheless, the order of magnitude of $\text{BR}(\mu \to e \gamma)$ for a fixed flavor-violating parameter can often be predicted. We summarize the behavior by plotting the correlations as well as resulting bounds on the flavor-violating parameters under various assumptions on the MSSM spectrum.

A survey for low stau yields in the MSSM

We study the implications of LHC results for the abundance of long-lived staus after freeze-out from thermal equilibrium in a super-WIMP dark matter scenario. We classify regions in the MSSM parameter space according to the stau yield, considering all possible co-annihilation effects as well as the effects of resonances and large Higgs-sfermion couplings. Afterwards, we examine the viability of these regions after imposing experimental and theoretical constraints, in particular a Higgs mass around 125 GeV and null-searches for heavy stable charged particles (HSCP) at the LHC. We work in a pMSSM framework and perform a Monte Carlo scan over the parameter space. To interpret the HSCP searches in our scenario, we consider all potentially important superparticle production processes, developing a fast estimator for NLO cross sections for electroweak and strong production at the LHC. After applying all constraints, we find that stau yields below 10^-14 occur only for resonant annihilation via a heavy Higgs in combination with either co-annihilation or large left-right stau mixing. We encounter allowed points with yields as low as 2x10^-16, thus satisfying limits from big bang nucleosynthesis even for large stau lifetimes.

SO(10) as a framework for natural supersymmetry

We consider an SO(10) grand unified theory in which the ratio of the SU(2)_W and SU(3)_c gaugino masses satisfy M_2/M_3 \approx 3, which results in the realization of natural supersymmetry. In the MSSM parameter space this relation looks artificial, but in the SO(10) case it results from a field with a designated vacuum expectation value. We consider two models, namely M_1:M_2:M_3=-1/5:3:1 (Case I), and M_1:M_2:M_3=-5:3:1 (Case II). Focusing on ameliorating the little hierarchy problem, we explore the parameter space of these models which yield small fine-tuning measuring parameters (natural supersymmetry) at the electroweak scale (\Delta_{EW}) as well as at the high scale (\Delta_{HS}). Although both models allow for the solution of the little hierarchy problem, the predicted sparticle spectra can differ markedly in the two cases. Depending on the ratio of the bino mass to the other gaugino masses, Case I leads to stau lepton masses of around a 100 GeV, while in Case II, the stau slepton masses are in the several TeV range. In Case I, the bino-like neutralino can be as light as 90 GeV, while the gluino is heavier than 2 TeV or so. In Case II, due to gluino-bino near degeneracy, the bino cannot be lighter than a TeV or so. Having a light neutralino with sizable bino-higgsino mixture in Case I allows the direct dark matter search experiments to test this class of models.

Implications of the 98 GeV and 125 GeV Higgs scenarios in nondecoupling supersymmetry with updated ATLAS, CMS, and PLANCK data

We discuss both MSSM and NMSSM scenarios in which the lightest Higgs boson with $m_h=98$~GeV is consistent with the small excess ($\sim 2.3 \sigma$) observed at the LEP in $e^+ e^-\rightarrow Zh$, with $h \rightarrow b {\bar b}$ process and the heavier Higgs boson of mass close to 125~GeV as the observed candidate of the SM Higgs like particle at the LHC. We show the allowed regions in the non-decoupling Higgs zone of MSSM parameter space which are consistent with several low energy constraints coming from heavy flavour physics, latest experimental data on Higgs signals and lower limit on superparticle masses from 7~TeV and 8~TeV LHC run. We also implement the constraints from the relic density of the cold dark matter as obtained from the recent PLANCK data. Additionally, we discuss the possibility of observing the light Higgs boson of mass 98~GeV at the 14~TeV LHC run via $pp \rightarrow V h$, with $h \rightarrow b \bar b$ using the technique of jet substructure. Our analysis shows that at 14~TeV LHC run with 300 ${\rm fb}^{-1}$ luminosity the signal efficiency of such a light Higgs boson is at most 2.5$\sigma$. Finally, we make a comment on the prospect of proposed $e^+ e^-$ ILC to discover/exclude this light Higgs boson.

Naturalness of light neutralino dark matter in pMSSM after LHC, XENON100 and Planck data

Abstract We examine the possibility of a light (below 46 GeV) neutralino dark matter (DM) candidate within the 19-parameter phenomenological Minimal Supersymmetric Standard Model (pMSSM) in the light of various recent experimental results, especially from the LHC, XENON100, and Planck. We also study the extent of electroweak fine-tuning for such a light neutralino scenario in view of the null results from the searches for supersymmetry so far. Using a Markov Chain Monte Carlo likelihood analysis of the full pMSSM parameter space, we find that a neutralino DM with mass ≳ 10 GeV can in principle still satisfy all the existing constraints. Our light neutralino solutions can be broadly divided into two regions: (i) The solutions in the 10–30 GeV neutralino mass range are highly fine-tuned and require the existence of light selectrons (below 100 GeV) in order to satisfy the observed DM relic density. We note that these are not yet conclusively ruled out by the existing LEP/LHC results, and a dedicated analysis valid for a non-unified gaugino mass spectrum is required to exclude this possibility. (ii) The solutions with low fine-tuning are mainly in the 30–46 GeV neutralino mass range. However, a major portion of it is already ruled out by the latest XENON100 upper limits on its spin-independent direct detection cross section, and the rest of the allowed points are within the XENON1T projected limit. Thus, we show that the allowed MSSM parameter space for a light neutralino DM below the LEP limit of 46 GeV, possible in supersymmetric models without gaugino mass unification, could be completely accessible in near future. This might be useful in view of the recent claims for positive hints of a DM signal in some direct detection experiments.

Consistent on shell renormalisation of electroweakinos in the complex MSSM: LHC and LC predictions

Abstract We extend the formalism developed in ref. [53] for the renormalisation of the chargino-neutralino sector to the most general case of the MSSM with complex parameters. We show that products of imaginary parts arising from MSSM parameters and from absorptive parts of loop integrals can already contribute to predictions for physical observables at the one-loop level, and demonstrate that the consistent treatment of such contributions gives rise to non-trivial structure, either in the field renormalisation constants or the corrections associated with the external legs of the considered diagrams. We furthermore point out that the phases of the parameters in the chargino-neutralino sector do not need to be renormalised at the one-loop level, and demonstrate that the appropriate choice for the mass parameters used as input for the on-shell conditions depends both on the process and the region of MSSM parameter space under consideration. As an application, we compute the complete one-loop results in the MSSM with complex parameters for the process $ {h_a}\to \widetilde{\chi}_i^{+}\widetilde{\chi}_j^{-} $ (Higgs-propagator corrections have been incorporated up to the two-loop level), which may be of interest for SUSY Higgs searches at the LHC, and for chargino pair-production at an e + e − Linear Collider, $ {e^{+}}{e^{-}}\to \widetilde{\chi}_i^{+}\widetilde{\chi}_j^{-} $ . We investigate the dependence of the theoretical predictions on the phases of the MSSM parameters, analysing in particular the numerical relevance of the absorptive parts of loop integrals.

Heavy MSSM Higgs production at the LHC and decays to WW , ZZ at higher orders

In this paper we discuss the production of a heavy scalar MSSM Higgs boson H and its subsequent decays into pairs of electroweak gauge bosons WW and ZZ. We perform a scan over the relevant MSSM parameters, using constraints from direct Higgs searches and several low-energy observables. We then compare the possible size of the pp -> H -> WW,ZZ cross sections with corresponding Standard Model cross sections. We also include the full MSSM vertex corrections to the H -> WW,ZZ decay and combine them with the Higgs propagator corrections, paying special attention to the IR-divergent contributions. We find that the vertex corrections can be as large as -30% in MSSM parameter space regions which are currently probed by Higgs searches at the LHC. Once the sensitivity of these searches reaches two percent of the SM signal strength the vertex corrections can be numerically as important as the leading order and Higgs self-energy corrections and have to be considered when setting limits on MSSM parameters.