Higgs sector of the MSSM: lepton flavor violation at colliders and neutralino dark matter
M. Cannoni, O. Panella
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6 pages, 2 figures, Prepared for the proceedings of the workshop: "LC09: $e^+ e^-$ Physics at the TeV Scale and the Dark Matter Connection", 21-24 September 2009, Perugia, Italy
We examine the prospects for the detection of Higgs mediated lepton flavor violation at LHC and at a photon collider in the minimal supersymmetric standard model with large lepton flavor violating mass insertions in the $μ-τ$ sector constraining the parameter space with several experimental bounds. We find rates probably too small to be observed at future experiments if models have to accommodate for a neutralino relic density as measured by WMAP and explain the $(g-2)_μ$ anomaly: better prospects are found if these two constraints are applied only as upper bounds. The spin-independent neutralino-nucleon cross section in the studied constrained parameter space is just below the present CDMS limit while gamma rates from neutralino annihilation in the halo are strongly suppressed.
The 1-loop computation of the processes $\tchi_i \tchi_j \to γZ$ has been performed at an arbitrary c.m. energy for any pair of MSSM neutralinos. As an application suitable for Dark Matter (DM) searches, the neutralino-neutralino annihilation is studied at the limiting case of vanishing relative velocity, describing the present DM distribution in the galactic halo; and at a relative velocity of about 0.5, determining the neutralino relic density contributions. The most useful situation is obviously for $i=j=1$, but the case of non-identical neutralinos may also be useful in some corners of the…
Extending the Higgs sector of the MSSM by the addition of a gauge singlet scalar field can remedy the mu problem. We explore the implications of extended models for both the spectrum of the neutralinos and the cascade decays of the neutralinos and charginos. Extra steps due to light decoupled neutralinos in the cascade decays of both neutralinos and charginos allow an excess of trilepton events compared to the MSSM and the existence of events with higher lepton multiplicity. Additionally, displaced vertices of the chi_2^0 due to small decay widths in some models may be observable.
The LEP experiments give a lower bound on the neutralino mass of about 46 GeV which, however, relies on a supersymmetric grand unification relation. Dropping this assumption, the experimental lower bound on the neutralino mass vanishes completely. Recent analyses suggest, however, that in the minimal supersymmetric standard model (MSSM), a light neutralino dark matter candidate has a lower bound on its mass of about 7 GeV. In light of this, we investigate the mass sensitivity at the ILC for very light neutralinos. We study slepton pair production, followed by the decay of the sleptons to a lep…
We study neutralino sectors in extensions of the MSSM that dynamically generate the mu-term. The extra neutralino states are superpartners of the Higgs singlets and/or additional gauge bosons. The extended models may have distinct lightest neutralino properties which can have important influences on their phenomenology. We consider constraints on the lightest neutralino from LEP, Tevatron, and (g-2)_mu measurements and the relic density of the dark matter. The lightest neutralino can be extremely light and/or dominated by its singlino component which does not couple directly to SM particles ex…
We study the associated production of selectrons and neutralinos with subsequent leptonic decay of the selectron in eγscattering within the framework of MSSM and NMSSM. Due to the weak couplings of singlino dominated neutralinos, associated neutralino production e^+ + e^- -> neutralino_1 + neutralino_2 at a linear collider can be strongly suppressed in some regions of the parameter space. Then the process e + gamma -> selectron_{L/R} + neutralino_{1/2} -> e + neutralino_{1/2} + neutralino_1 can give additional informations on the underlying theory and the character of neutralino_1 and neutrali…
The present status of the calculation of radiative corrections to chargino and neutralino pair production processes in the MSSM is summarized. The main focus will be on the use of the on-shell renormalization scheme for charginos and neutralinos in conjunction with DR-bar parameters, such as those of the SPA conventions. Associated soft and hard bremsstrahlung and an appropriate separation of QED-like parts in the full one-loop contributions will be addressed.
The complete 1-loop computation of the processes $(\tchi^0_i \tchi^0_j \leftrightarrowγγ, ~ gg)$, for any pair of the four MSSM neutralinos, has been performed for an arbitrary c.m energy. As a first application suitable for Dark Matter (DM) searches, the neutralino-neutralino annihilation is studied at relative velocities $v/c\simeq 10^{-3}$ describing the present DM distribution in the galactic halo, and $v/c\simeq 0.5$ determining neutralino relic density contributions. Numerical results are presented for 31 MSSM benchmark models indicating considerable sensitivity to the input parameters. …
We discuss constraints on SUSY models with non-unified gaugino masses. We concentrate on the slepton/gaugino sector and obtain a lower limit on the neutralino mass combining direct limits, indirect limits as well as relic density measurements.
We study the contribution of charginos and neutralinos of the Minimal SUSY extension of the Standard model (MSSM) to the 1-loop vertices ZAA, ZZA, ZZZ, and examine the related cancellation of anomalies. It is found that when the SUSY parameter μsatisfies |μ| >> M,M', m_W, the couplings of charginos and neutralinos with the gauge bosons become purely vectorial, and then their contribution to the amplitudes for ZAA, ZZA and ZZZ vanish, which implies that this sector of the MSSM does not generate a Wess-Zumino term. We evaluate also the contribution of charginos and neutralinos to the ρparameter,…
The addition of non-renormalizable terms involving the Higgs fields to the MSSM ameliorates the little hierarchy problem of the MSSM. For neutralino dark matter, new regions for which the relic abundance of the LSP is consistent with WMAP (as the bulk region and the stop coannihilation region) are now permitted. In this framework, we analyze in detail first the direct dark matter detection prospects in a XENON-like experiment; then we study the capability of detecting gamma-rays produced in the annihilation of neutralino LSPs in the FERMI satellite.
In the MSSM, the presence of CP phases can have a significant impact on the neutralino relic abundance. These phase effectsare on the one hand due to shifts in the masses, on the other hand due to modifications of the couplings. Typical variations in Omega h^2 solely from modifications in the couplings are of order 10%-100%.
We study neutralino sectors in extensions of the MSSM that dynamically generate the mu-term. The extra neutralino states are superpartners of the Higgs singlets and/or additional gauge bosons. The extended models may have distinct lightest neutralino properties which can have important influences on their phenomenology. We consider constraints on the lightest neutralino from LEP, Tevatron, and (g-2)_mu measurements and the relic density of the dark matter. The lightest neutralino can be extremely light and/or dominated by its singlino component, which does not couple directly to SM particles e…
We have calculated the two-loop strong interaction corrections to the neutralino pole masses in the DRbar'-scheme in the Minimal Supersymmetric Standard Model (MSSM). We have performed a detailed numerical analysis for a particular point in the parameter space and found corrections of a few tenths of a percent. We agree with previously derived analytic formulae for two-loop corrections to fermion masses.
We study the neutralino relic density and the neutralino-proton elastic scattering cross sections in the minimal supersymmetric standard model (MSSM) with CP-violating phases. We include all the final states to the neutralino pair annihilation cross section at the tree level, taking into account the mixing between the CP-even and CP-odd neutral Higgs fields. We show that variations of the relic density and the elastic scattering cross sections with the CP-violating phases are significant. In particular, interferences between the major contributions in the neutralino annihilation cross section …
We study the implications of dimension five operators involving Higgs chiral superfields for the masses of neutralinos and charginos in the minimal supersymmetric standard model (MSSM). These operators can arise from additional interactions beyond those of MSSM involving new degrees of freedom at or above the TeV scale. In addition to the masses of the neutralinos and charginos, we study the sum rules involving the masses and squared masses of these particles for different gaugino mass patterns in presence of the dimension five operators in the context of MSSM. We derive a relation for the hig…
In a minimal supersymmetric extension of the standard model (MSSM) with explicit CP violation a mass of the lightest Higgs boson H_1 in the range 7 GeV} < M_{H_1} < 10 GeV is experimentally allowed by present accelerator limits. In the same scenario a lightest neutralino as light as 2.9 GeV can be a viable dark matter candidate, provided that a departure from the usual GUT relation among gaugino masses is assumed.
Within the low-energy effective Minimal Supersymmetric extension of Standard Model (effMSSM) we calculated the neutralino relic density taking into account slepton-neutralino and neutralino-chargino/neutralino coannihilation channels. We performed comparative study of these channels and obtained that both of them give sizable contributions to the reduction of the relic density. Due to these coannihilation processes some models (mostly with large neutralino masses) enter into the cosmologically interesting region for relic density, but other models leave this region. Nevertheless, in general, t…
The CP-violating effects in the neutralino sector of the MSSM can be observed in event-counting type experiments, i.e. without the need of exploiting variables sensitive to beam or neutralino polarization. On the other hand, such CP-odd effects in the chargino sector can be generated only at the loop level. We contrast the two sectors and present results of full one-loop analysis of the CP-odd asymmetry in the non-diagonal chargino pair production in e+e- collisions.
Three dark matter direct detection experiments, DAMA, COGENT and CRESST, have reported a possible signal of WIMP interaction corresponding to very light particles, close to the edge of the XENON 100 and CDMS sensitivity. Imposing the latest constraints from colliders, flavour physics, electroweak precision tests and direct and indirect dark matter searches, we show that viable MSSM scenarios with a light neutralino, in agreement with all the present data, are feasible. An analysis of the characteristics of the resulting scenarios will be presented.
The neutralino relic density is calculated in the low-energy effective Minimal Supersymmetric extension of Standard Model (effMSSM). The slepton-neutralino, squark-neutralino and neutralino/chargino-neutralino coannihilation channels are taking into account. The comparative study of these coannihilations is performed and demonstrated that all of them give the sizable contributions to the reduction of the neutralino relic density. It is shown that the predictions for direct dark matter detection rates are not strongly affected by these coannihilation channels in the effMSSM.
Within the low-energy effective Minimal Supersymmetric extension of the Standard Model (effMSSM) we calculate the neutralino relic density taking into account slepton-neutralino, squark-neutralino and neutralino/chargino- neutralino coannihilation channels. By including squark (stop and sbottom) coannihilation channels we extend our comparative study to all allowed coannihilations and obtain the general result that all of them give sizable contributions to the reduction of the neutralino relic density. Due to these coannihilation processes some models (mostly with large neutralino masses) ente…
We revisit the case of a light neutralino LSP in the framework of the MSSM. We consider a model with eleven free parameters. We show that all scenarios where the annihilation of light neutralinos rely mainly on the exchange of a light pseudoscalar are excluded by direct detection searches and by Fermi measurements of the gamma-flux from dwarf spheroidal galaxies. On the other hand, we find scenarios with light sleptons that satisfy all collider and astroparticle physics constraints. In this case, the lower limit on the LSP mass is 12.6 GeV. We discuss how the parameter space of the model will …
We consider the Minimal Supersymmetric Standard Model (MSSM) with varying amounts of non-universality in the soft supersymmetry-breaking contributions to the Higgs scalar masses. In addition to the constrained MSSM (CMSSM) in which these are universal with the soft supersymmetry-breaking contributions to the squark and slepton masses at the input GUT scale, we consider scenarios in which both the Higgs masses are non-universal by the same amount (NUHM1), and scenarios in which they are independently non-universal (NUHM2). As the lightest neutralino is a dark matter candidate, we demand that th…
We discuss the scenario of light neutralino dark matter in the minimal supersymmetric standard model, which is motivated by the results of some of the direct detection experiments --- DAMA, CoGENT, and CRESST. We update our previous analysis with the latest results of the LHC. We show that new LHC constraints disfavour the parameter region that can reproduce the results of DAMA and CoGENT.
The MIMAC project aims to provide a nominal fluorine detector for directional detection of galactic dark matter recoil events. Its expected behavior reaches an important part of the predicted spin dependent elastic scattering interactions of the supersymmetric neutralino with protons. Hence, the parameter space in the MSSM and the NMSSM models with neutralino dark matter could be probed by such experimental efforts. In particular, a good sensitivity to spin dependent interactions tackles parameter space regions to which the predictions on spin independent interactions and indirect signatures a…
We discuss the choice of input parameters for the renormalization of the chargino and neutralino sector in the minimal supersymmetric standard model (MSSM) in the on-shell scheme. We show that one should chose the masses of a bino-like, a wino-like and a higgsino-like state as inputs in order to avoid large corrections to the masses of the other eigenstates in this sector. We also show that schemes where the higgsino-like input state is a neutralino are more stable than those where the mass of the higgsino-like chargino is used as input. The most stable scheme uses the masses of the wino-like …
The region of low neutralino masses as low as (5-10) GeV has attracted attention recently due to the possibility of excess events above background in dark matter detectors. An analysis of spin independent neutralino-proton cross sections $\SI$ which includes this low mass region is given. The analysis is done in MSSM with radiative electroweak symmetry breaking (REWSB). It is found that cross sections as large as $10^{-40}$ cm$^2$ can be accommodated in MSSM within the REWSB framework. However, inclusion of sparticle mass limits from current experiments, as well as lower limits on the Higgs se…
The neutralino sector in E_6 inspired supersymmetric models with extra neutral gauge bosons and singlet Higgs fields contains additional gaugino and singlino states compared to the MSSM. We discuss the neutralino mixing in rank 5 and rank 6 models and analyze the supersymmetric parameter space where the light neutralinos have mainly singlino or MSSM character. The neutralino character, resonance effects of the new gauge bosons and, assuming mSUGRA-type RGEs, different selectron masses lead to significant differences between the MSSM and the extended models in neutralino production at an e^+e^-…
We discuss ILC measurements for a specific MSSM scenario with CP phases, where the lightest neutralino is a good candidate for dark matter, annihilating efficiently through t-channel exchange of light staus. These prospective (CP-even) ILC measurements are then used to fit the underlying model parameters. A collider prediction of the relic density of the neutralino from this fit gives 0.116<Omega h^2<0.19 at 95% CL. CP-odd observables, while being a direct signal of CP violation, do not help in further constraining Omega h^2. The interplay with (in)direct detection of dark matter and with meas…
The requirement that the MSSM remain an acceptable effective field theory up to energies beyond the weak scale constrains the sparticle spectrum, and hence the permissible ranges of cold dark matter neutralino-proton cross sections. Specifically, squarks are generally much heavier than sleptons if no tachyons are to appear before the GUT scale ~10^16 GeV, or even before 10 TeV. We display explicitly the allowed ranges of effective squark and slepton masses at the weak scale, and the cross-section ranges allowed if the MSSM is to remain valid without tachyons up to 10 TeV or the GUT scale. The …
The mass spectrum of the chargino--neutralino sector in the minimal supersymmetric standard model (MSSM) is calculated at the one-loop level, based on the complete set of one-loop diagrams. On-shell renormalization conditions are applied to determine the counterterms for the gaugino-mass-parameters $M_1, M_2$ and the Higgsino-mass parameter $μ$. The input is fixed in terms of three pole masses (two charginos and one neutralino); the other pole masses receive a shift with respect to the tree-level masses, which can amount to several GeV. The detailed evaluation shows that both the fermionic/sfe…
The dark matter relic density being a powerful observable to constrain models of new physics, the recent experimental progress calls for more precise theoretical predictions. On the particle physics side, improvements are to be made in the calculation of the (co)annihilation cross-section of the dark matter particle. We present the project DM@NLO which aims at calculating the neutralino (co)annihilation cross-section in the MSSM including radiative corrections in QCD. In the present document, we briefly review selected results for different (co)annihilation processes. We then discuss the estim…
We review the evaluation of two-body decay modes of charginos in the Minimal Supersymmetric Standard Model with complex parameters (cMSSM). Assuming heavy scalar quarks we take into account all decay channels involving charginos, neutralinos, (scalar) leptons, Higgs bosons and SM gauge bosons. The evaluation of the decay widths is based on a full one-loop calculation including hard and soft QED radiation. Here we focus on the decays involving the Lightest Supersymmetric Particle (LSP), i.e. the lightest neutralino, or a heavier neutralino and a W boson. The higher-order corrections of the char…
We consider a class of $U(1)^\prime$-extended MSSM in which the $U(1)^{\prime}$ symmetry is broken by vacuum expectation values (VEVs) of four MSSM singlet fields. While one MSSM singlet field interacts with the MSSM Higgs fields, three of them interact only with each other in forming a secluded sector. Assigning universal $U(1)^{\prime}$ charges for three families, the anomaly cancellation condition requires exotic fields which are assumed to be heavy and decoupled. We discuss a variety of $U(1)^{\prime}$ charge assignments and anomaly cancellation, $Z^{\prime}/Z$ hierarchy, neutralinos, char…
We compute one loop radiative corrections to the physical neutralino masses in the MSSM considering the dominant top-stop contributions. We present a numerical renormalization group analysis of the feasibility of the radiative gauge symmetry breaking parametrized by the standard soft supersymmetry breaking terms. Although the above computed effects can be in principle large for extreme values of the Yukawa couplings, they do not in general exceed a few per cent for most of the parameter space. Therefore tree level constraints imposed on the gluino mass $m_{\tilde{g}}$ and on the superpotential…
We perform for the Large Hadron Collider (LHC) a detailed study of charged Higgs boson production via the top-bottom quark associated mode followed by decays into a chargino and a neutralino, with masses and couplings as given by the general Minimal Supersymmetric Standard Model (MSSM). We focus our attention on the region of parameter space where the charged Higgs is heavier than the top quark, with intermediate values of tan beta. In this region, the identification of charged Higgs bosons via decays into Standard Model (SM) particles has proven to be ineffective. Modelling the CMS detector, …
We present the complete electroweak one-loop corrections to the partial widths for two-body decays of a chargino (neutralino) into a W-boson and a neutralino (chargino). We perform the calculation for the minimal and the next-to-minimal supersymmetric standard model using an on-shell renormalization scheme. Particular attention is paid to the question of gauge invariance which is achieved using the so-called pinch technique. Furthermore we show that these corrections show a strong parameter dependence and usually are in the range of 1-10 percent if the neutralino involved is a higgsino or wino…
This work investigates the possibility of a long-lived stop squark in supersymmetric models with the neutralino as the lightest supersymmetric particle (LSP). We study the implications of meta-stable stops on the sparticle mass spectra and the dark matter density. We find that in order to obtain a sufficiently long stop lifetime so as to be observable as a stable R-hadron at an LHC experiment, we need to fine tune the mass degeneracy between the stop and the LSP considerably. This increases the stop-neutralino coanihilation cross section, leaving the neutralino relic density lower than what is…
Supersymmetric models provide many new complex phases which lead to CP violating effects in collider experiments. As an example, CP-sensitive triple product asymmetries in neutralino production and subsequent leptonic two-body decays are studied within the Minimal Supersymmetric Standard Model. A full ILD detector simulation has been performed at a center of mass energy of 500GeV, including the relevant Standard Model background processes, a realistic beam energy spectrum, beam backgrounds and a beam polarization of 80% and -60% for the electron and positron beams, respectively. Assuming an in…
It has recently been pointed out that a component of the observed gamma ray emission in the low-latitudes of Fermi Bubble has a spectral shape that can be explained by a 10 GeV dark matter (DM) annihilating to tau leptons with a cross-section of 2 x 10^{-27} cm^3/s. Motivated by this possibility, we revisit the annihilation of a 10 GeV neutralino DM in the MSSM via stau exchange. The required stau masses and mixing, consistent with LEP direct search and electroweak precision constraints, are correlated with a possible enhancement of the Higgs decay rate to two photons. We also explore the impl…
In the Minimal Supersymmetric Extension of the Standard Model (MSSM) the higgsino mass parameter $μ$ appears both in the masses of the Higgs bosons and in the neutralino mass matrix. Electroweak finetuning therefore prefers small values of $|μ|$. On the other hand, bino--like neutralinos make a good dark matter candidate. We show that current direct search limits then impose a strong lower bound on $|μ|$, in particular for $μ> 0$ or if the masses of the heavy Higgs bosons of the MSSM are near their current limit from LHC searches. There is therefore some tension between finetuning and neutrali…
We study the spin-independent neutralino Dark Matter scattering off heavy nuclei in the MSSM. We identify analytically the blind spots in direct detection for intermediate values of $m_A$. In the region where $μ$ and $M_{1,2}$ have opposite signs, there is not only a reduction of the lightest CP-even Higgs coupling to neutralinos, but also a destructive interference between the neutralino scattering through the exchange of the lightest CP-even Higgs and that through the exchange of the heaviest CP-even Higgs. At critical values of $m_A$, the tree-level contribution from the light Higgs exchang…
Searches for supersymmetry are among the most exciting physics goals at Run II of the Tevatron. In particular, in supersymmetric models with light charginos, neutralinos and sleptons, associated chargino--neutralino production can potentially be observed as multi-lepton events with missing energy. We discuss how, in the generic TeV-scale MSSM, the prospects for these chargino-neutralino searches are impacted by cosmological considerations, namely the neutralino relic abundance and direct detection limits. We also discuss what an observation of chargino-neutralino production at the Tevatron wou…
For the search for charginos and neutralinos in the Minimal Supersymmetric Standard Model (MSSM) as well as for future precision analyses of these particles an accurate knowledge of their production and decay properties is mandatory. We evaluate the cross sections for the chargino and neutralino production at e+e- colliders in the MSSM with complex parameters (cMSSM). The evaluation is based on a full one-loop calculation of the production mechanisms e+e- -> cha_c cha_c' and e+e- -> neu_n neu_n', including soft and hard photon radiation. We mostly restricted ourselves to a version of our renor…
We re-assess the exclusion limits on the parameters describing the supersymmetric (SUSY) electroweak sector of the MSSM obtained from the search for direct chargino-neutralino production at the LHC. We start from published limits obtained in simplified models, where for the case of heavy sleptons the relevant branching ratio, BR(neu2->neu1 Z), is set to one. We show how the decay mode neu2->neu1 h, which cannot be neglected in any realistic model once kinematically allowed, substantially reduces the excluded parameter region. We analyze the dependence of the excluded regions on the phase of th…
In this work, the following reactions have been studied: $e^- e^+ \to H^- \widetildeχ_{1}^+ \widetildeχ_{1}^o$, $e^{-}e^{+}\to h\widetildeχ_{1}^{+}\widetildeχ_{1}^{-}$, $e^{-}e^{+}\to h\widetildeχ_{1}^{o}\widetildeχ_{1}^{o}$, $e^{-}e^{+}\to h H^{+} H^{-}$, where $\widetildeχ_{1}^{\pm}$ is the chargino and $\widetildeχ_{1}^{0}$ is the neutralino. $h$ represent the lightest neutral Higgs boson, and $H_3$ (sometimes refered to as $A$) is the pseudoscalar Higgs boson. The work went to calculate the differential cross section due to each Feynman diagram, then, the total cross section for each react…
We study implications of two dark matter candidate events at CDMS-II on the neutralino dark matter scenario in the supersymmetric standard model, in light of the recent lattice simulation on the strange quark content of a nucleon. The scattering rate of neutralino-nucleon is dominated by Higgs exchange processes and the mass of heavy Higgs boson is predicted for the neutralino of Bino-Higgsino mixing state. In the case of Wino-Higgsino mixing, the Higgs sector may not be constrained.
The flat directions LLe and udd within the minimal supersymmetric Standard Model provide all the necessary ingredients for a successful inflation with the right amplitude of the scalar density perturbations, negligible gravity waves and the spectral tilt within 2σobserved range 0.92 \leq n_s \leq 1.0. In this paper we explore the available parameter space for inflation in conjunction with a thermal cold dark matter abundance within the minimal supergravity model. Remarkably for the inflaton, which is a combination of squarks and sleptons, there is a stau-neutralino coannihilation region below …
We study thermal neutralino dark matter in an effective field theory extension of the MSSM, called "Beyond the MSSM" (BMSSM) in Dine, Seiberg and Thomas (2007). In this class of effective field theories, the field content of the MSSM is unchanged, but the little hierarchy problem is alleviated by allowing small corrections to the Higgs/higgsino part of the Lagrangian. We perform parameter scans and compute the dark matter relic density. The light Higgsino LSP scenario is modified the most; we find new regions of parameter space compared to the standard MSSM. This involves interesting interplay…
We discuss constraints on SUSY models with non-unified gaugino masses and R_P conservation. We derive a lower bound on the neutralino mass combining the direct limits from LEP, the indirect limits from gmuon, bsgamma, Bsmumu and the relic density constraint from WMAP. The lightest neutralino (mneutralino=6GeV) is found in models with a light pseudoscalar with MA<200GeV and a large value for $tanβ$. Models with heavy pseudoscalars lead to mneutralino>18(29)GeV for $\tanβ=50(10)$. We show that even a very conservative bound from the muon anomalous magnetic moment can increase the lower bound on …
We assess the potential of detecting a charged Higgs boson of the MSSM at the LHC via its decays into a chargino and a neutralino. We focus our attention on the region of parameter space with $m_{H^{\pm}} > m_t$ and $3 \lsim tan(beta) \lsim 10$, where identification of the $H^{\pm}$ via other decay modes has proven to be ineffective. Searching for means to plug this hole, we simulate the decays $H^{\pm} --> {\tildeχ}_1^{\pm} {\tildeχ}_1^0$ and $H^{\pm} --> {\tildeχ}_1^{\pm} {\tildeχ}_2^0, {\tildeχ}_1^{\pm} {\tildeχ}_3^0$ --- the former can yield a single hard lepton (from the chargino decay) w…
The prediction of neutralino dark matter is generally regarded as one of the successes of the Minimal Supersymmetric Standard Model (MSSM). However the successful regions of parameter space allowed by WMAP and collider constraints are quite restricted. We discuss fine-tuning with respect to both dark matter and Electroweak Symmetry Breaking (EWSB) and explore regions of MSSM parameter space with non-universal gaugino and third family scalar masses in which neutralino dark matter may be implemented naturally. In particular allowing non-universal gauginos opens up the bulk region that allows Bin…
We show that the interplay between the LHC and the e^+ e^- International Linear Collider (ILC) with sqrt{s}=500 GeV might be crucial for the discrimination between the minimal and next-to-minimal supersymmetric standard model. We present an NMSSM scenario that cannot be distinguished from the MSSM by cross sections and mass measurements if only the light neutralinos and the lightest chargino are kinematically accessible, even if one of the neutralinos has a significant singlino component. Mass predictions for the heavier neutralinos from the ILC analysis and their observation at the LHC lead t…
We compute analytically the tree-level annihilation rates of a collection of non-relativistic neutralino and chargino two-particle states in the general MSSM, including the previously unknown off-diagonal rates. The results are prerequisites to the calculation of the Sommerfeld enhancement in the MSSM, which will be presented in subsequent work. They can also be used to obtain concise analytic expressions for MSSM dark matter pair annihilation in the present Universe for a large number of exclusive two-particle final states.
We apply the covariant derivative expansion method to integrate out the neutralinos and charginos in the minimal supersymmetric Standard Model. The results are presented as set of pure bosonic dimension-6 operators in the Standard Model effective field theory. Nontrivial chirality dependence in fermionic covariant derivative expansion are discussed carefully. The results are checked by computing the $hγγ$ effective coupling and the electroweak oblique parameters using the Standard Model effective field theory with our effective operators and direct loop calculation. In global fitting the propo…
We examine the properties of relic neutralinos in the regions of the parameter space selected by recent fits to all the electroweak observables within the Minimal Supersymmetric Standard Model. We discuss the relic neutralino cosmic abundance and the direct detection rates for these most likely supersymmetric configurations. We employ the relevant experimental bounds to constrain the set of the best-fit configurations and discuss the discovery potential of the direct search for relic neutralinos.
Light neutralino dark matter can be achieved in the Minimal Supersymmetric Standard Model if staus are rather light, with mass around 100 GeV. We perform a detailed analysis of the relevant supersymmetric parameter space, including also the possibility of light selectons and smuons, and of light higgsino- or wino-like charginos. In addition to the latest limits from direct and indirect detection of dark matter, ATLAS and CMS constraints on electroweak-inos and on sleptons are taken into account using a "simplified models" framework. Measurements of the properties of the Higgs boson at 125 GeV,…
It is pointed out that a bino-dominated well-tempered bino-higgsino in the Minimal Supersymmetric Standard Model (MSSM) with heavy non-SM- like scalars can satisfy the 2016 LUX constraints on the scattering cross-section of dark matter on nuclei only if $\tanβ$ is smaller than about 3. This, together with the Higgs mass constraint, sets a lower bound on the stops masses of about 25 TeV. The LUX constraints can be satisfied for larger $\tanβ$ if the non-SM-like Higgs bosons are light enough. However, this region of parameter space is strongly constrained by recent LHC results of the Higgs boson…
