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 $\tanβ$ via a small value of coupling $A_μ'$ 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 $m_{\tilde {μ_1}}$. 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 $B \rightarrow X_s +γ$ for large values of $\tanβ$, a scenario unfavourable in pMSSM.
Using the effective potential method, we computed one-loop corrections to the mass matrix of neutral Higgs bosons of the Non-Holomorphic Supersymmetric Standard Model (NHSSM) with explicit CP violation, where the radiative corrections due to the quarks and squarks of the third generation were taken into account. We observed that the non-holomorphic trilinear couplings can compete with the holomorphic ones in CP violating issues for the mass and mixing of the neutral Higgs bosons.
The operators that break supersymmetry can be holomorphic or non-holomorphic in structure. The latter do not pose any problem for gauge hierarchy and are soft provided that the particle spectrum does not contain any gauge singlets. In minimal supersymmetric model (MSSM) we discuss the impact of non-holomorphic soft-breaking terms on the Higgs sector. We find that non-holomorphic operators can cause significant changes as are best exhibited by the correlation between the masses of the charginos and Higgs bosons.
Non-Holomorphic MSSM (NHSSM) shows various promising features that are not easily obtained in MSSM. However, the additional Non-Holomorphic (NH) trilinear interactions that attribute to the interesting phenomenological features, also modify the effective scalar potential of the model significantly. We derive analytic constraints involving trilinear parameters $A_t'$ and $A_b'$ that exclude global charge and color breaking minima (CCB). Since the analytic constraints are obtained considering specific directions in the multi-dimensional field space, we further probe the applicability of these co…
The theoretical structure of the Higgs sector of the Minimal Supersymmetric Standard Model (MSSM) is briefly described. An outline of Higgs phenomenology at future lepton colliders is presented, and some opportunities for probing the physics of the MSSM Higgs sector at an e-e- collider are considered.
The Minimal Supersymmetric Standard Model (MSSM) can be extended to include non-holomorphic trilinear soft supersymmetry (SUSY) breaking interactions that may have distinct signatures. We consider non-vanishing off-diagonal entries of the coupling matrices associated with holomorphic (of MSSM) and non-holomorphic trilinear terms corresponding to sleptons with elements $A^l_{ij}$ and $A^{\prime l}_{ij}$. We first improve the MSSM charge breaking minima condition of the vacuum to include the off-diagonal entries $A^l_{ij}$ (with $i \neq j$). We further extend this analysis for non-holomorphic tr…
We show that in the CMSSM with the non-holomorphic soft SUSY breaking terms, the Yukawa coupling unification of the third family fermions at the GUT scale, called $ t-b-τ$ Yukawa unification (YU), is possible under the recent collider and Dark Matter results. The YU parameter can also be found $ R_{tbτ} \approx 1 $, called perfect unification. We find that the squark masses exceed 3 TeV while the stau can be considerably lighter. In the case of YU, the $ \tanβ$ is in the interval $ [46,55] $. We obtain bino-like dark matter (DM) of mass in the range of $ 0.6$ TeV $ \lesssim m_{χ_{1}^{0}} \less…
The CP properties of Higgs bosons can be probed through their s-channel resonance productions via photon-photon collisions by use of circularly and/or linearly polarized backscattered laser photons at a TeV-scale linear e^+ e^- collider. Exploiting this powerful tool, we investigate in detail the Higgs sector of the minimal supersymmetric Standard Model with explicit CP violation.
We study the production processes $e^+e^-\to H^0_iZ$, $H^0_iH^0_j$ and $H^0_iν_e\overline ν_e$ in the context of the CP violating MSSM. In a given channel we show that the cross-section for all i (=1,2,3) can be above 0.1 fb provided $M_{H_{2,3}}\la 300$ GeV. This should be detectable at a Next Linear Collider and would provide evidence for scalar-pseudoscalar mixing.
In this work we study implications of additional non-holomorphic soft breaking terms (mu', A'_t, A'_b and A'_tau) on the MSSM phenomenology. By respecting the existing bounds on the mass measurements and restrictions coming from certain B-decays, we probe reactions of the MSSM to these additional soft breaking terms. We provide examples in which some slightly excluded solutions of the MSSM can be made to be consistent with the current experimental results. During this, even after applying additional fine-tuning constraints the non-holomorphic terms are allowed to be as large as hundreds of GeV…
We present the analytical and numerical investigations of top-charm associated production at the LHC in the framework of the R-parity violating MSSM. The numerical analysis of their production rates is carried out in the mSUGRA scenario with some typical parameter sets. The results show that the cross sections of associated $t\bar{c}(\bar{t}c)$ production via gluon-gluon fusion can reach 5% of that via $d\bar{d}$ annihilation. The total cross section will reach the order of $10 \sim 10^2 ~fb$ and the cross sections are strongly related to the R-parity violating parameters.
We study the phenomenological implications of the Higgs sector CP violation at a photon collider. In our model, the CP violation is radiatively induced by the non-trivial CP phases of the third-generation scalar-quark sector in the MSSM. We re-evaluate the $s$-channel resonance production cross sections and the polarization asymmetries of the neutral Higgs bosons based on the calculation of the mass matrix of the neutral Higgs bosons which is valid for any values of the relevant SUSY parameters. The CP properties of the Higgs bosons can be precisely probed through their $s$-channel resonance p…
In the presence of the supersymmetric CP phases, e^+ e^- \to Z^{*} \to h A scattering is analyzed, with special emphasis on Z^{*} h A vertex, taking into account radiatve corrections due to dominant top quark and top squark loops in the Higgs sector as well as the vertex formfactors. It is found that the lightest Higgs remains essentially CP-even whereas the heavier ones mix with each other strongly. Moreover, the supersymmetric CP phases are found to create tree-level couplings between a pseudoscalar and identical sfermion mass eigenstates which, together with the radiative corrections in the…
We propose using the lightest CP-even Higgs boson in the minimal supersymmetric standard model (MSSM) to probe the stop sector. Unlike measuring stop masses in production/decay processes which requires knowledge of masses and mixing angles of other superparticles, the strategy depends little on supersymmetric parameters other than those in the stop sector in a large region of parameter space. We show that measurements of the Higgs mass and the production rate in the gluon fusion channel, the dominant channel at the LHC, allow for determination of two parameters in the stop mass-squared matrix,…
We perform a systematic study of the production of a third-generation fermion-pair, $μ^+μ^-\to f\bar{f}$ for $f=τ^-,b$, and t in the minimal supersymmetric standard model (MSSM) with explicit CP violation, which is induced radiatively by soft trilinear interactions related to squarks of the third generation. We classify all the observables for probing the CP property of the Higgs bosons constructed by the initial muon beam polarization along with the unpolarized final fermions and with the final-fermion polarization configuration of equal helicity, respectively. The observables allow for compl…
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 …
In this article we consider chirally enhanced corrections to Higgs vertices in the most general MSSM. We include the contributions stemming from bilinear-terms, from the trilinear A-terms and their non-holomorphic analogues, the A'-terms, which couple squarks to the "wrong" Higgs field. We perform a consistent renormalization of the Higgs vertices beyond the decoupling limit M_SUSY->infinity, using a purely diagrammatic approach. The cancellation of the different contributions in and beyond the decoupling limit is discussed and the possible size of decoupling effects which occur if the SUSY pa…
In the MSSM weak boson fusion produces the two CP even Higgs bosons with a combined strength equivalent to the production of the Standard Model Higgs boson. The tau tau decay mode --- supplemented by gamma gamma --- provides a highly significant signal for at least one of the CP even Higgs bosons at the LHC with reasonable luminosity. The accessible parameter space covers the entire physical range which will be left unexplored by LEP2.
The measurement of the anomalous magnetic moment of the muon exhibits a long standing discrepancy compared to the Standard model prediction. In this paper, we concentrate on this issue in the framework of $R$-parity violating Minimal supersymmetric standard model. Such a scenario provides substantial contribution to the anomalous magnetic moment of the muon while satisfying constraints from low energy experimental observables as well as neutrino mass. In addition, we point out that the implication of such operators satisfying muon $g-2$ are immense from the perspective of the LHC experiment, l…
The recent Fermilab muon $g-2$ result and the same for electron due to fine-structure constant measurement through ${}^{133}{\rm Cs}$ matter-wave interferometry are probed in relation to MSSM with non-holomorphic (NH) trilinear soft SUSY breaking terms, referred as NHSSM. Supersymmetric contributions to charged lepton $(g-2)_l$ can be enhanced via the new trilinear terms involving a wrong Higgs coupling with left and right-handed scalars. Unlike many MSSM based analyses, the model does not require a light electroweakino, or light sleptons, or unequal left and right slepton masses, or a very la…
We report on an extensive analysis of FCNC and CPV effects in SUSY theories. We present results for Delta F=2 and Delta F=1 processes governed by b --> s transitions both in the low and high tanbeta regime, focussing in particular on S_psi_phi, the phase of Bs mixing. We emphasize that while the MFV framework is not suited to explain potentially large effects in S_psi_phi as indicated by recent data from CDF and D0, models with large right-right mass insertions in the 32 sector provide natural frameworks to account for such effects. Exemplarily we consider two SUSY models based on an abelian a…
We discuss singlet extensions of the MSSM with $\Z4^R$ symmetry. We show that holomorphic zeros can avoid a potentially large coefficient of the term linear in the singlet. The emerging model has both an effective mu term and a supersymmetric mass term for the singlet mu_N which are controlled by the gravitino mass. The mu term turns out to be suppressed against mu_N by about one or two orders of magnitude. We argue that this class of models might provide us with a solution to the little hierarchy problem of the MSSM.
We discuss a possibility to probe right-handed weak hadronic currents in rare semileptonic b -> s transitions. It is shown that within models involving right-handed as well as left-handed quark currents (LR models) one can expect a strong enhancement of the right-handed K* production in B -> K* l+ l- decays compared with models including only left-handed quark currents (SM, MSSM). Hence an experimental study of the transverse asymmetry of the produced K* mesons provides a clear test of the presence of the right-handed quark currents and a possibiltity to discriminate between the MSSM and LR ex…
In full one-loop generality and in next-to-leading order in QCD, we study rare top to Higgs boson flavour changing decay processes $t\to q h$ with $q=u,c$ quarks, in the general MSSM with R-parity conservation. Our primary goal is to search for enhanced effects on $Br(t\to q h)$ that could be visible at current and high luminosity LHC running. To this end, we perform an analytical expansion of the amplitude in terms of flavour changing squark mass insertions that treats both cases of hierarchical and degenerate squark masses in a unified way. We identify two enhanced effects allowed by various…
In the CP-violating Minimal Supersymmetric Standard Model (MSSM), for certain values of the CP-violating phases associated to the universal trilinear couplings $(A_t, A_b)$ and the gluino mass $(M_{\tilde g})$, e.g., $Φ_{\rm{CP}} = 60^\circ$ or $90^\circ$, for $M_{H^+} \lsim 140 $ GeV and $\tan β\sim 2-5 $, the lightest Higgs boson mass ($M_{H_1}$) is $\lsim 50 $ GeV. This mass interval is still allowed from standard LEP Higgs searches because of a strongly suppressed $H_1ZZ$ coupling. However, in the same region of parameter space in which these two conditions occur, the $H_1 H^\mp W^\pm $ co…
We explore supersymmetric contributions to the decay $K_S^0\rightarrowμ^+μ^-$, in light of current experimental data. The Standard Model (SM) predicts $\mathcal{B}(K_S^0\rightarrowμ^+μ^-)\approx5\times 10^{-12}$. We find that contributions arising from flavour violating Higgs penguins can enhance the branching fraction up to $\approx 35\times 10^{-12}$ within different scenarios of the Minimal Supersymmetric Standard Model (MSSM), as well as suppress it down to $\approx 0.78\times 10^{-12}$. Regions with fine-tuned parameters can bring the branching fraction up to the current experimental uppe…
We explore the ability of current and future dark matter and collider experiments in probing anomalous magnetic moment of the muon, $(g-2)_μ$, within the Minimal Supersymmetric Standard Model (MSSM). We find that the latest PandaX-II/LUX-2016 data gives a strong constraint on parameter space that accommodates the $(g-2)_μ$ within $2σ$ range, which will be further excluded by the upcoming XENON-1T (2017) experiment. We also find that a 100 TeV $pp$ collider can cover most of our surviving samples that satisfy DM relic density within $3σ$ range through $Z$ or $h$ resonant effect by searching for…
We investigate the capability of directional detectors to probe neutralino dark matter in the Minimal Supersymmetric Standard Model and the Next-to-Minimal Supersymmetric Standard Model with parameters defined at the weak scale. We show that directional detectors such as the future MIMAC detector will probe spin dependent dark matter scattering on nucleons that are beyond the reach of current spin independent detectors. The complementarity between indirect searches, in particular using gamma rays from dwarf spheroidal galaxies, spin dependent and spin independent direct search techniques is em…
In the MSSM the quasi-infra-red fixed point for the top-quark Yukawa coupling gives rise to specific predictions for the soft-breaking parameters. We discuss the extent to which these predictions are modified by the introduction of additional ``non-holomorphic'' soft-breaking terms. We also show that in a specific class of theories there exists an RG-invariant trajectory for the ``non-holomorphic'' terms, which can be understood using a holomorphic spurion term.
We investigate Higgs boson pair production at hadron colliders for Higgs boson masses m_H\leq 140 GeV and rare decay of one of the two Higgs bosons. While in the Standard Model the number of events is quite low at the LHC, a first, albeit not very precise, measurement of the Higgs self-coupling is possible in the gg -> HH -> b\bar{b}γγchannel. A luminosity-upgraded LHC could improve this measurement considerably. A 200 TeV VLHC could make a measurement of the Higgs self-coupling competitive with a next-generation linear collider. In the MSSM we find a significant region with observable Higgs p…
We present some highlights on the complementaries of the Higgs and SUSY searches at the LHC, using the 8 and 13 TeV results. In particular, we discuss the constraints that can be obtained on the MSSM parameters by the determination of the Higgs boson mass and couplings. In addition, we investigate the interplay with heavy Higgs searches, and evaluate how higher LHC luminosities and a future linear collider can help probing the pMSSM Higgs sector and reconstructing the underlying parameters.
Given the recent constraints from the dark matter (DM) direct detections, we examine a light GeV-scale (2-30 GeV) neutralino DM in the alignment limit of the Minimal Supersymmetric Standard Model (MSSM). In this limit without decoupling, the heavy CP-even scalar $H$ plays the role of the Standard Model (SM) Higgs boson while the other scalar $h$ can be rather light so that the DM can annihilate through the $h$ resonance or into a pair of $h$ to achieve the observed relic density. With the current collider and cosmological constraints, we find that such a light neutralino DM above 6 GeV can be …
We review the physics potential of the GigaZ option of the International Linear Collider (ILC) for probing the Minimal Supersymmetric Standard Model (MSSM) via the sensitivity of the electroweak precision observables measured at the ILC to quantum corrections. A particular focus is put on the effective leptonic weak mixing angle, sin^2_theta_eff. The MSSM predictions take into account the complete one-loop results including the full complex phase dependence, all available MSSM two-loop corrections as well as the full Standard Model (SM) results. We find that the anticipated experimental accura…
If supersymmetry (SUSY) is realized at the electroweak scale, its underlying structure and breaking mechanism may be explored with great precision by a future linear $e^+ e^-$ collider (LC) with a clean environment, tunable collision energy, high luminosity polarized beams, and additional $e^-e^-$, $eγ$ and $γγ$ modes. We review a few recent developments for determining fundamental SUSY and Higgs parameters, measuring CP violating $H/A$ mixing in the decoupling regime and probing the next--to--minimal supersymmetric standard model at the LC.
The "top-down" approach to minimal supersymmetric standard model (MSSM) phenomenology provides model-dependent indications for a natural stop mass. The approach is based on specific assumptions about the supersymmetry-breaking energy scale and parameters degeneracies. In order to determine robust predictions we update the stop-mass prediction within the MSSM with 25 parameters (MSSM-25) by including electroweak fine-tuning as "naturalness data" during the Bayesian fits of the parameters to experimental data. The approximately prior-independent results show that imposing naturalness, taken here…
The favoured R-parity violating SUSY scenarios for the anomalous HERA events correspond to top and charm squark production via the $λ'_{131}$ and $λ'_{121}$ couplings. In both cases the corresponding electronic branching fractions of the squarks are expected to be $\ll 1$. Consequently the canonical leptoquark signature is incapable of probing these scenarios at the Tevatron collider over most of the MSSM parameter space. We suggest alternative signatures for probing them at Tevatron, which seem to be viable over the entire range of MSSM parameters.
Using a Markov chain Monte Carlo approach, we find the allowed parameter space of a MSSM model with seven free parameters. In this model universality conditions at the GUT scale are imposed on the gaugino sector. We require in particular that the relic density of dark matter saturates the value extracted from cosmological measurements assuming a standard cosmological scenario. We characterize the parameter space of the model that satisfies experimental constraints and illustrate the complementarity of the LHC searches, B-physics observables and direct dark matter searches for further probing t…
We compute the one-loop supersymmetric (SUSY) contributions to the weak charges of the electron ($Q_W^e$), proton ($Q_W^p$), and cesium nucleus ($Q_W^{\rm Cs}$) in the Minimal Supersymmetric Standard Model (MSSM). Such contributions can generate several percent corrections to the corresponding Standard Model values. The magnitudes of the SUSY loop corrections to $Q_W^e$ and $Q_W^p$ are correlated over nearly all of the MSSM parameter space and result in an increase in the magnitudes of these weak charges. In contrast, the effects on $Q_W^{\rm Cs}$ are considerably smaller and are equally likel…
The U(1) extended supersymmetric standard model (UMSSM) can accommodate a Higgs boson at 125 GeV without relying on large corrections from the top/stop sector. After imposing LHC results on the Higgs sector, on B-physics and on new particle searches as well as dark matter constraints, we show that this model offers two viable dark matter candidates, the right-handed (RH) sneutrino or the neutralino. Limits on supersymmetric partners from LHC simplified model searches are imposed using SModelS and allow for light squarks and gluinos. Moreover the upper limit on the relic abundance often favours…
Since the top quark FCNC processes are extremely supressed in the Standard Model (SM) but could be greatly enhanced in some new physics models, they could serve as a smoking gun for new physics hunting at the LHC. In this brief review we summarize the new physics predictions for various top quark FCNC processes at the LHC by focusing on two typical models: the minimal supersymmetric model (MSSM) and the topcolor-assisted technicolor (TC2) model. The conclusion is: (1) Both new physics models can greatly enhance the SM predictions by several orders; (2) The TC2 model allows for largest enhancem…
If supersymmetry is spontaneously at a low energy scale then the resulting gravitino would be very light. The interaction strength of the longitudinal components of such a light gravitino to electron-selectron pair then becomes comparable to that of electroweak interactions. Such a light gravitino could modify the cross-section for $e^_L e^_R-->\tilde {e}_L\tilde {e}_R$ from its MSSM value. Precision measurement of this cross-section could therefore be used to probe the low energy SUSY breaking scale.
In the minimal supersymmetric standard model (MSSM), the μ-parameter and the trilinear coupling A_t may be generically complex and can affect various observables at B factories. Imposing the edm constraints, we find that there is no new large phase shift in the B^0 - \bar{B^0} mixing, CP violating dilepton asymmetry is smaller than 0.1 %, and the direct CP violation in B\to X_s γcan be as large as \sim \pm 16 %.
We evaluate the amount of fine-tuning in constrained versions of the minimal supersymmetric standard model (MSSM), with different boundary conditions at the GUT scale. Specifically we study the fully constrained version as well as the cases of non-universal Higgs and gaugino masses. We allow for the presence of additional non-holomorphic soft-terms which we show further relax the fine-tuning. Of particular importance is the possibility of a Higgsino mass term and we discuss possible origins for such a term in UV complete models. We point out that loop corrections typically lead to a reduction …
It is known that in the absence of a gauge singlet field, a specific class of supersymmetry (SUSY) breaking non-holomorphic (NH) terms can be soft breaking in nature so that they may be considered along with the Minimal Supersymmetric Standard Model (MSSM) and beyond. There have been studies related to these terms in minimal supergravity based models. Consideration of an F-type SUSY breaking scenario in the hidden sector with two chiral superfields however showed Planck scale suppression of such terms. In an unbiased point of view for the sources of SUSY breaking, the NH terms in a phenomenolo…
This letter presents new results on the combined sensitivity of the LHC and underground dark matter search experiments to the lightest neutralino as WIMP candidate in the minimal Supersymmetric extension of the Standard Model. We show that monojet searches significantly extend the sensitivity to the neutralino mass in scenarios where scalar quarks are nearly degenerate in mass with it. The inclusion of the latest bound by the LUX experiment on the neutralino-nucleon spin-independent scattering cross section expands this sensitivity further, highlighting the remarkable complementarity of jets/$…
We discuss the use of fermion polarization for studying neutral Higgs bosons at a photon collider. To this aim we construct polarization asymmetries which can isolate the contribution of a Higgs boson $ϕ$ in $γγ\to f \bar f$, $f=τ/t$, from that of the QED continuum. This can help in getting information on the $γγϕ$ coupling in case $ϕ$ is a CP eigenstate. We also construct CP-violating asymmetries which can probe CP mixing in case $ϕ$ has indeterminate CP. Furthermore, we take the MSSM with CP violation as an example to demonstrate the potential of these asymmetries in a numerical analysis. We…
We study CP violation in the two-body decay of a scalar tau into a neutralino and a tau, which should be probed at the LHC and ILC. From the normal tau polarization, a CP asymmetry is defined which is sensitive to the CP phases of the trilinear scalar coupling parameter $A_τ$, the gaugino mass parameter $M_1$, and the higgsino mass parameter $μ$ in the stau-neutralino sector of the Minimal Supersymmetric Standard Model. Asymmetries of more than 70% are obtained in scenarios with strong stau mixing. As a result, detectable CP asymmetries in stau decays at the LHC are found, motivating further d…
A canonical signature of the Minimal Supersymmetric Standard Model (MSSM) is the presence of a neutral Higgs boson with mass bounded from above by about 135 GeV and Standard Model (SM)-like couplings to the electroweak gauge bosons. In this note we investigate the reach of the Tevatron collider for the MSSM Higgs sector parameter space associated with a variety of high-scale minimal models of supersymmetry (SUSY)-breaking, including the Constrained MSSM (CMSSM), minimal Gauge Mediated SUSY-breaking (mGMSB), and minimal Anomaly Mediated SUSY-breaking (mAMSB). We find that the Tevatron can provi…
The lightest neutralino, assumed to be the lightest supersymmetric particle, is proposed to be a dark matter (DM) candidate for the mass $\cal{O}$(100) GeV. Constraints from various direct dark matter detection experiments and Planck measurements exclude a substantial region of parameter space of the minimal supersymmetric standard model (MSSM). However, a "mild-tempered" neutralino with dominant bino composition and a little admixture of Higgsino is found to be a viable candidate for DM. Within the MSSM framework, we revisit the allowed region of parameter space that is consistent with all ex…
The chiral structure of supersymmetric particle couplings involving third generation Standard Model fermions depends on left-right squark and slepton mixings as well as gaugino-higgsino mixings. The shapes and intercorrelations of invariant mass distributions of a first or second generation lepton with bottoms and taus arising from adjacent branches of SUSY cascade decays are shown to be a sensitive probe of this chiral structure. All possible cascade decays that can give rise to such correlations within the MSSM are considered. For bottom-lepton correlations the distinctive structure of the i…
The stau-neutralino coannihilation provides a feasible way to accommodate the observed cosmological dark matter (DM) relic density in the minimal supersymmetric standard model (MSSM). In such a coannihilation mechanism the stau mass usually has an upper bound since its annihilation rate becomes small with the increase of DM mass. Inspired by this observation, we examine the upper limit of stau mass in the parameter space with a large mixing of staus. We find that the stau pair may dominantly annihilate into dibosons and hence the upper bound on the stau mass ($\sim400$ GeV) obtained from the $…
We explore `benchmark surfaces' suitable for studying the phenomenology of Higgs bosons in the minimal supersymmetric extension of the Standard Model (MSSM), which are chosen so that the supersymmetric relic density is generally compatible with the range of cold dark matter density preferred by WMAP and other observations. These benchmark surfaces are specified assuming that gaugino masses m_{1/2}, soft trilinear supersymmetry-breaking parameters A_0 and the soft supersymmetry-breaking contributions m_0 to the squark and slepton masses are universal, but not those associated with the Higgs mul…
The forthcoming precision data on lepton flavour violating decays require precise and efficient calculations in New Physics models. In this article lepton flavour violating processes within the Minimal Supersymmetric Standard Model (MSSM) are calculated using the method based on the Flavour Expansion Theorem, a recently developed technique performing a purely algebraic mass-insertion expansion of the amplitudes. The expansion in both flavour-violating and flavour-conserving off-diagonal terms of sfermion and supersymmetric fermion mass matrices is considered. In this way the relevant processes…
We consider the natural supersymmetry scenario in the framework of the R-parity conserving minimal supersymmetric standard model (called natural MSSM) and examine the observability of stop pair production at the LHC. We first scan the parameters of this scenario under various experimental constraints, including the SM-like Higgs boson mass, the indirect limits from precision electroweak data and B-decays. Then in the allowed parameter space we study the stop pair production at the LHC followed by the stop decay into a top quark plus a lightest neutralino or into a bottom quark plus a chargino.…
In the context of the Minimal Supersymmetric extension of the Standard Model (MSSM), we reanalyze the search for the heavier CP-even $H$ and CP-odd $A$ neutral Higgs bosons at the LHC in their production in the gluon-fusion mechanism and their decays into gauge and lighter $h$ bosons and into top quark pairs. We show that only when considering these processes, that one can fully cover the entire parameter space of the Higgs sector of the model. Indeed, they are sensitive to the low $\tanβ$ and high Higgs mass ranges, complementing the traditional searches for high mass resonances decaying into…
Top squark (stop) is a crucial part of supersymmetric models (SUSY) to understand the naturalness problem. Other than the traditional stop pair production, the single production via electroweak interaction provides signals with distinctive features which could help confirm the existence of the top squark. In this paper, we investigate the observability of stop through the mono-top channel of the single stop production at the future proton-proton colliders, FCC-hh and SPPC, in a simplified Minimal Supersymmetric Standard Model (MSSM). With the integrated luminosity of 3000 $\text{fb}^{-1}$, we …
The minimal supersymmetric extension of the Standard Model (SM) is a well motivated scenario for physics beyond the SM, which allows a perturbative description of the theory up to scales of the order of the Grand Unification scale, where gauge couplings unify. The Higgs mass parameter is insensitive to the ultraviolet physics and is only sensitive to the scale of soft supersymmetry breaking parameters. Present collider bounds suggest that the characteristic values of these parameters may be significantly larger than the weak scale. Large values of the soft breaking parameters, however, induce …
The search for the Higgs boson is entering a decisive phase. The Large Hadron Collider experiments have collected more than 1 fb$^{-1}$ of data and are now capable of efficiently probing the high Higgs mass region, $m_H > 140$ GeV. The low mass region is more challenging at the LHC, but if the Higgs has Standard Model (SM)-like properties, the LHC should find evidence for it by the end of next year. In low energy supersymmetric extensions of the SM, the situation is similar for large values of the CP-odd Higgs mass $m_A$, but more interesting for lower values of $m_A$. The ($\sqrt{s}$ =7 TeV) …
We investigate the sensitivity of observables measurable in e^+ e^-, gamma gamma and mu^+ mu^- collisions for distinguishing the properties of the light neutral CP-even Higgs boson in the minimal supersymmetric extension of the Standard Model (MSSM) from those of a Standard Model (SM) Higgs boson with the same mass. We explore first the available parameter space in the constrained MSSM (CMSSM), with universal soft supersymmetry-breaking parameters, incorporating the most recent direct limits on sparticle and Higgs masses, the indirect constraints from b to s gamma and g_mu - 2, and the cosmolo…
