The impact of priors and observables on parameter inferences in the Constrained MSSM
R. Trotta, F. Feroz, M. P. Hobson, L. Roszkowski, R. Ruiz de Austri
备注：
Minor changes, extended discussion of profile likelihood. Matches JHEPaccepted version. SuperBayeS code with MultiNest algorithm available at http://www.superbayes.org
We use a newly released version of the SuperBayeS code to analyze the impact of the choice of priors and the influence of various constraints on the statistical conclusions for the preferred values of the parameters of the Constrained MSSM. We assess the effect in a Bayesian framework and compare it with an alternative likelihood-based measure of a profile likelihood. We employ a new scanning algorithm (MultiNest) which increases the computational efficiency by a factor ~200 with respect to previously used techniques. We demonstrate that the currently available data are not yet sufficiently constraining to allow one to determine the preferred values of CMSSM parameters in a way that is completely independent of the choice of priors and statistical measures. While b->s gamma generally favors large m_0, this is in some contrast with the preference for low values of m_0 and m_1/2 that is almost entirely a consequence of a combination of prior effects and a single constraint coming from the anomalous magnetic moment of the muon, which remains somewhat controversial. Using an information-theoretical measure, we find that the cosmological dark matter abundance determination provides at least 80% of the total constraining power of all available observables. Despite the remaining uncertainties, prospects for direct detection in the CMSSM remain excellent, with the spin-independent neutralino-proton cross section almost guaranteed above sigma_SI ~ 10^{-10} pb, independently of the choice of priors or statistics. Likewise, gluino and lightest Higgs discovery at the LHC remain highly encouraging. While in this work we have used the CMSSM as particle physics model, our formalism and scanning technique can be readily applied to a wider class of models with several free parameters.
A combined analysis for Z boson observables and the quantity Δr within the framework of the Minimal Supersymmetric Standard Model is presented. Contributions from supersymmetric particles are discussed and upper and lower bounds for the MSSM predictions are given.
The calculation of electroweak precision observables in the MSSM is reviewed. The description of the 1997 data and the results of updated global fits are discussed in comparison with the Standard Model.
We show that the physical minimum of the Constrained MSSM is only free from dangerous charge and colour breaking minima in the region of parameter space bounded by 110< m_1/2< 400 GeV and 80< m_0< 170 GeV. In the remaining regions, the cosmology is severely constrained.
The precision observables M_W and g-2 of the muon are discussed in the framework of the MSSM. Recent progress in the evaluation of the theoretical predictions is described, and the MSSM predictions are compared with the SM predictions and the experimental values.
The current status of the theoretical predictions for the electroweak precision observables M_W, sin^2_theta_eff and m_h within the MSSM is briefly reviewed. The impact of recent electroweak two-loop results to the quantity Delta_rho is analysed and the sensitivity of the electroweak precision observables to the top-quark Yukawa coupling is investigated. Furthermore the level of precision necessary to match the experimental accuracy at the next generation of colliders is discussed.
We present the currently most accurate prediction of Z pole observables such as sin^2 theta_eff, Gamma_Z, R_b, R_l, and sigma^0_had in the Minimal Supersymmetric Standard Model (MSSM). We 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 SM results. We furthermore include higher-order corrections in the MSSM Higgs boson sector, entering via virtual Higgs boson contributions. For Gamma(Z -> neutralino{1} neutralino{1}) we present a full one-loop calculation. We analyse the impact of the differ…
Recent higher-order results for precision observables in the Standard Model (SM) and the Minimal Supersymmetric Standard Model (MSSM) and for the neutral CP-even Higgs-boson masses of the MSSM are summarized. Furthermore a brief discussion of the technical aspects of evaluating higher-order corrections in the electroweak theory is given. In the SM, results for the Higgs-mass dependence of the precision observables are analyzed. The exact two-loop results for the Higgs-mass dependence of the fermionic contributions are compared with the results of an expansion in the top-quark mass up to next-t…
Higher-order results for electroweak precision observables in the Standard Model are analyzed in view of the experimental accuracies achievable at the present and the next generation of colliders, and the indirect prediction of the Higgs-boson mass from the precision data is discussed. Within the MSSM, two-loop results for the lightest CP-even Higgs-boson mass are confronted with the exclusion limits from LEP. Possible precision tests of the MSSM at a future linear collider are furthermore investigated.
The leading electroweak MSSM two-loop corrections to the electroweak precision observables are calculated. They are obtained by evaluating the two-loop O(α_t^2), O(α_t α_b), O(α_b^2) contributions to the quantity Δρin the limit of heavy scalar quarks, i.e. we consider the contributions of a Two-Higgs-Doublet model with MSSM restrictions. The full analytic result for arbitrary values of the lightest CP-even Higgs boson mass is presented. The numerical effects of the leading electroweak MSSM two-loop corrections on the precision observables M_W and sin^2(theta_eff) are analyzed. The electroweak …
The evaluation of the two-loop MSSM-contributions to the electroweak precision observables M_W and s_w^eff at order(alpha_t^2), order(alpha_t alpha_b), order(alpha_b^2) is presented. These contributions enter via Delta(rho), and it is explained in detail how one can retain the true, non-vanishing value of the MSSM Higgs boson mass M_h in spite of using the gauge-less limit in the calculation. The numerical results can be sizeable, in particular for strong squark mixing. By comparing the results in the on-shell and DR-bar renormalization schemes, the remaining theoretical uncertainty is found t…
We consider charged Lepton Flavour Violation (LFV) in the Constrained Minimal Supersymmetric Standard Model, extended to include the see-saw mechanism with Constrained Sequential Dominance (CSD), where CSD provides a natural see-saw explanation of tri-bimaximal neutrino mixing. When charged lepton corrections to tri-bimaximal neutrino mixing are included, we discover characteristic correlations among the LFV branching ratios, depending on the mass ordering of the right-handed neutrinos, with a pronounced dependence on the leptonic mixing angle $θ_{13}$ (and in some cases also on the Dirac CP p…
We provide a detailed analysis of the impact of the newly measured optimised observables in the B -> K* mu+ mu- decay by the LHCb experiment. The analysis is performed in the MSSM, both in the context of the usual constrained scenarios, and in the context of a more general set-up where the SUSY partner masses are independent. We show that the global agreement of the MSSM solutions with the data is still very good. Nevertheless, especially in the constrained scenarios, the limits from B -> K* mu+ mu- are now very strong, and are at the same level as the well-known b -> s gamma constraints. We d…
Study of the MSSM in large tan$β$ regime has to include correlations between the constraints presented by the low energy values of the b quark mass and $BR(b\to sγ)$. Both quantities receive SUSY contributions enhanced by tan$β$ and have a major impact on the MSSM analysis. Here we summarize the results of such a study constrained by minimal SO(10) unification. We show the best fits, in the $(m_0,M_{1/2})$ plane, obtained in the global analysis spanned over the gauge, Yukawa and SUSY parameter space at the unification scale. Two distinct fits describe the available low-energy data very well. T…
We consider constraints on $\cp$-violating phases in the Constrained Minimal Supersymmetric Standard Model. We find that by combining cosmological limits on gaugino masses with experimental bounds on the neutron and electron electric dipole moments, we can constrain the phase of the Higgs mixing mass $μ$ to be $|θ_μ| < π/10$, independent of choices of the other mass parameters in the model. The other $\cp$-violating phase $θ_A$ is essentially unconstrained.
The leading electroweak MSSM two-loop corrections to the $ρ$-parameter are calculated. They are obtained by evaluating the two-loop self-energies of the Z and the W boson at O(Gf^2 m_t^4) in the limit of heavy scalar quarks. A very compact expression is derived, depending on the ratio of the CP-odd Higgs boson mass, M_A, and the top quark mass, m_t. Expressions for the limiting cases M_A >> m_t and M_A << m_t are also given. The decoupling of the non-SM contribution in the limit M_A -> oo is verified at the two-loop level. The numerical effect of the leading electroweak MSSM two-loop correctio…
We analyze CP violation in the supersymmetric standard model (MSSM) embedded minimally into a left-right symmetric gauge structure with the seesaw mechanism for neutrino masses. With the plausible assumption of universal scalar masses it is shown that CP violation in the hadron sector of the MSSM is described by a single phase residing in the supersymmetry breaking Lagrangian. This improves the CP properties of the MSSM by providing a natural solution to the SUSY CP problem. Furthermore, $ε'/ε$ vanishes in this model above the seesaw scale; extrapolation to the weak scale then leads to a predi…
Additional sources of CP violation in the MSSM may affect B-meson mixings and decays, even in scenarios with minimal flavour violation (MFV). We formulate the maximally CP-violating and minimally flavour-violating (MCPMFV) variant of the MSSM, which has 19 parameters, including 6 phases that violate CP. We then develop a manifestly flavour-covariant effective Lagrangian formalism for calculating Higgs-mediated FCNC observables in the MSSM at large tan(beta), and analyze within the MCPMFV framework FCNC and other processes involving B mesons. We include a new class of dominant subleading contri…
New data on the anomalous magnetic moment of the muon together with the b->s gamma decay rate and Higgs limits are considered within the supergravity inspired constrained minimal supersymmetric model. We perform a global statistical chi2 analysis of these data and show that the allowed region of parameter space is bounded from below by the Higgs limit, which depends on the trilinear coupling and from above by the anomalous magnetic moment.
We show that the best fits of the MSSM constrained by a simple SO(10) SUSY GUT are consistent with the present data on the muon anomalous magnetic moment. The best fits assume rather large values of tan$β\approx 50$, and in our analysis they are not {\em a priori} correlated in any way, directly or indirectly, with the experimental limit on $a_μ$. Regions in the SUSY parameter space, which are currently ruled out because of too large $a_μ^{SUSY}$, are already excluded in the global fit by excessive corrections to $m_b$, unacceptable $BR(b\to sγ)$, or direct experimental limits on sparticle mas…
The leading corrections to electroweak precision observables in the MSSM with non-minimal flavor violation (NMFV) are calculated and the effects on M_W and sin^2 theta_eff are analyzed. The corrections are obtained by evaluating the full one-loop contributions from the third and second generation scalar quarks, including the mixing in the scalar top and charm, as well as in the scalar bottom and strange sector. Furthermore the leading corrections to the mass of the lightest MSSM Higgs boson, m_h, is obtained. The electroweak one-loop contribution to M_W can amount up to 140 MeV and up to 70x10…
A brief overview over the phenomenology of the MSSM at present and future colliders is given. The complementarity of indirect tests of the model via precision observables and of the information from the direct production of SUSY particles is emphasized. If the lightest Higgs boson of the MSSM will be detected, its mass will also play an important role as a precision observable.
Low-energy results from measurements of leptonic dipole moments are used to derive constraints on the CP-violating phases of the dimensionful parameters of the minimal supersymmetric extension of the standard model (MSSM). We use these (known) bounds to investigate the impact of these phases on CP-even cross sections at high-energy e^+e^- and e^-e^- colliders. To that end we define two measures of the significance with which the existence of non--vanishing phases could be deduced from the measurements of these cross sections. We find that highly significant evidence for deviations from the CP-…
We consider some specific inverse problem or "bottom-up" reconstruction strategies at the LHC for both general and constrained MSSM parameters, starting from a plausibly limited set of sparticle identification and mass measurements, using mainly gluino/squark cascade decays, plus eventually the lightest Higgs boson mass. For the three naturally separated sectors of: gaugino/Higgsino, squark/slepton, and Higgs parameters, we examine different step-by-step algorithms based on rather simple, entirely analytical, inverted relations between masses and basic MSSM parameters. This includes also reaso…
We make a comparison of the predicted effective weak mixing angle, the Z-on resonance asymmetries and the W-boson mass to the LEP and SLD data at their present status. We find that the predicted MSSM values for the effective weak mixing angle are in agreement with the LEP+SLD average value for a ``heavy'' SUSY breaking scale while we observe an agreement with SLD data in the case of a ``light'' SUSY breaking scale. The resulting values for the W-boson mass and for the electron left-right asymmetries are compatible with CDF,UA2,DO and LEP data respectively. Unexpectedly we find that the supersy…
New data on the anomalous magnetic moment a_mu of the muon together with the b->s gamma decay rate are considered within the supergravity inspired constrained minimal supersymmetric model. We perform a global statistical chi^2 analysis of these data and show that the allowed region of parameter space is bounded from below by the Higgs limit, which depends on the trilinear coupling and from above by the anomalous magnetic moment a_mu. The newest b->s gamma data deviate 1.7 sigma from recent SM calculations and prefer a similar parameter region as the 2.6 sigma deviation from a_mu.
We use a new weak basis invariant approach to classify all the observable phases in any extension of the Standard Model (SM). We apply this formalism to determine the invariant CP phases in a simplified version of the Minimal Supersymmetric SM with only three non-trivial flavour structures. We propose four experimental measures to fix completely all the observable phases in the model. After these phases have been determined from experiment, we are able to make predictions on any other CP-violating observable in the theory, much in the same way as in the Standard Model all CP-violation observab…
We analyze two minimal supersymmetric constrained models with low-energy vector-like matter preserving gauge coupling unification. In one we add to the MSSM spectrum a pair of 5-plets of SU(5), in the other a pair of 10-plets. We show that the muon g-2 anomaly can be explained in these models while retaining perturbativity up to the unification scale, satisfying electroweak and flavor precision tests and current LHC data. We examine also some related phenomenological features of the models, including Higgs mass, fine-tuning, dark matter and several LHC signatures. We stress that, at least for …
Study of the MSSM in large tan$β$ regime has to include correlations between the constraints presented by the low energy values of the b quark mass and BR($b \to sγ$). Both quantities receive SUSY contributions enhanced by tan$β$ and have a major impact on the MSSM analysis. Here we summarize the results of such a study constrained by a complete SO(10) model. The dominant effects to the analysis come from third generation Yukawa couplings and a GUT threshold to $α_s$. We show that a small negative GUT correction to $α_s$ accommodates $α_s(M_Z) \leq 0.118$ and $δm_b^{SUSY} > 0$. The latter quan…
A summary of recent results obtained for higher-order corrections to precision observables in the Standard Model and the Minimal Supersymmetric Standard Model is given. In the Standard Model electroweak two-loop results valid for arbitrary values of the masses of the top quark, the Higgs boson and the gauge bosons are discussed. For the example of two specific diagrams the exact two-loop result is compared with the result of an expansion in the top-quark mass up to next-to-leading order. Furthermore the Higgs-mass dependence of the two-loop corrections to the relation between the gauge-boson m…
Recent higher-order results for the prediction of the W-boson mass, M_W, within the Standard Model are reviewed and an estimate of the remaining theoretical uncertainties of the electroweak precision observables is given. An updated version of a simple numerical parameterisation of the result for M_W is presented. Furthermore, leading electroweak two-loop contributions to the precision observables within the MSSM are discussed.
We study the Minimal Supersymmetric Standard Model (MSSM) constrained by unification assuming mSUGRA SUSY breaking. In particular this means that the three gauge couplings are unified at a {\it per cent} level, third generation yukawa couplings are unified at a $10 $% level, and at the unification scale $M_U\approx 10^{16}$ the SUSY breaking masses of squarks and sleptons are universal up to specific D-term contributions. At $M_U$ we also include right-handed neutrinos that are decoupled at their three respective scales. In a top-down global analysis we then find that there are two distinct be…
In this thesis we use the Effective Field Theory approach for supersymmetric theories, applied to two experimental domains : the search for the Higgs bosons at colliders and the Dark Matter observables. The reason for introducing an effective approach in the Higgs physics is that the simple supersymmetric extension of the Standard Model (the MSSM) is known to have a tightly constrained Higgs sector, in particular with a lightest Higgs mass difficult to raise without introducing some fine-tuning. Many specific expansions (as the NMSSM for instance) allow for a richer Higgs sector. In this case …
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So far the squarks have not been detected at the LHC indicating that they are heavier than a few hundred GeVs, if they exist. The lighter stop can be considerably lighter than the other squarks. We study the possibility that a supersymmetric partner of the top quark, stop, is the next-to-lightest supersymmetric particle in the constrained supersymmetric standard model. Various constraints, on top of the mass limits, are taken into an account, and the allowed parameter space for this scenario is determined. Observing stop which is the next-to-lightest supersymmetric particle at the LHC may be d…
Within the Constrained Minimal Supersymmetric Model (CMSSM) it is possible to predict the low energy gauge couplings and masses of the 3 generation particles from a few supergravity inspired parameters at the GUT scale. Moreover, the CMSSM predicts electroweak symmetry breaking due to large radiative corrections from the Yukawa couplings, thus relating the $Z^0$ boson mass to the top quark mass via the renormalization group equations (RGE). In addition, the cosmological constraints on the lifetime of the universe are considered in the fits. The new precise measurements of the strong coupling c…
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We study the minimal supersymmetric standard model (MSSM) with minimal flavor violation (MFV), imposing constraints from flavor physics observables and MSSM Higgs searches, in light of the recent discovery of a 125 GeV Higgs boson by ATLAS and CMS. We analyze the electroweak vacuum stability conditions to further restrict the MSSM parameter space. In addition, a connection to ultraviolet physics is shown via an implementation of renormalization group running, which determines the TeV-scale spectrum from a small set of minimal supergravity parameters. Finally, we investigate the impact from dar…
We discuss information theory as a tool to investigate constrained minimal supersymmetric Standard Model (CMSSM) in the light of observation of Higgs boson at the Large Hadron Collider. The entropy of the Higgs boson using its various detection modes has been constructed as a measure of the information and has been utilized to explore a wide range of CMSSM parameter space after including various experimental constraints from the LEP data, B-physics, electroweak precision observables and relic density of dark matter. According to our study while the lightest neutralino is preferred to have a ma…
We study the contributions of supersymmetric models with a $U(1)$ horizontal symmetry and only spontaneous CP breaking to various lepton flavor observables, such as $μ\to eγ$ and the electron electric dipole moment. We show that both a horizontal symmetry and a lack of explicit CP violation can alleviate the existing bounds from such observables. The undetermined $\mathcal{O}(1)$ coefficients in such mass matrix models muddle the interpretation of the bounds from various flavor observables. To overcome this, we define a new fine-tuning measure for different observables in such setups. This all…
In this work we study the Lepton Flavour Violating semileptonic $τ$ decays: 1) $τ\to μPP$ with $PP= π^+π^-, π^0π^0, K^+K^-, K^0 {\bar K}^0$; 2) $τ\to μP$ with $P=π^0, η, η'$ and 3) $τ\to μV$ with $V = ρ^0, ϕ$. We work within the context of two constrained MSSM scenarios: the CMSSM and NUHM. A full one-(SUSY)loop computation is presented and the importance of the various contributions, the $γ$-, $Z$-, and Higgs bosons mediated ones are analysed. The hadronization of quark bilinears is performed within the chiral framework. Some discrepancies in the predicted rates for BR($τ\to μη$), BR($τ\to μη…
We present an analysis of low energy CP violating observables in the Minimal Supersymmetric Standard Model (MSSM). We focus on the predictions of CP violation in b -> s transitions in the framework of a flavor blind MSSM, where the CKM matrix remains the only source of flavor violation, but additional CP violating phases are introduced in the soft SUSY breaking sector. We find large and strongly correlated effects in Delta F = 0 observables like the electric dipole moments (EDMs) of the electron and the neutron, as well as in Delta F = 1 observables like the time dependent CP asymmetries in B …
We study the constraints on the CP-violating soft-breaking phases in the minimal supersymmetric standard model using the limits on the chromoelectric dipole moment of the strange quark extracted from the neutron EDM experiment. Our investigation shows that the phase mediated by the gluino exchange diagram has to be very small, $ϕ\leq 8 10^{-4}$, for the common supersymmetric mass of the order of 100 GeV. Then, solving the renormalization group equations analytically by iterations, we calculate the electric dipole moment of the neutron in the MSSM with CP-conserving soft-breaking parameters for…
A non-Abelian flavour symmetry in a minimal supersymmetric standard model can explain the flavour structures in the Yukawa couplings and simultaneously solve the SUSY flavour problem. Similarly the SUSY CP problem can be solved if CP is spontaneously broken in the flavour sector. In this work, we present an explicit example of these statements with a SU(3) flavour symmetry and spontaneous CP violation. In addition, we show that it is still possible to find some significant deviation from the SM expectations as far as FCNC and CP violation are concerned. We find that large contributions can be …
Following previous works regarding electroweak precision tests in supersymmetry, we continue to explore their implications to the MSSM and NMSSM both of which are tightly constrained by the Higgs mass and its decay experiments at the LHC. We adopt universal squark, slepton mass of three generations, and A-term of all SM fermions. We determine the flows of both MSSM and NMSSM in the $S$-$T$ plane with increasing $\tanβ$ and/or $γγ$ rate. Either increasing the value of $R_γ$ or $\tanβ$, we find that the benchmark points tend to be pushed outside the contour at 99% CL in the MSSM, however, conver…
The electroweak symmetry is nonlinearly realized in an extension of the minimal supersymmetric standard model (MSSM) through an additional pair of constrained Higgs doublet superfields. The superpotential couplings of this constrained Higgs doublet pair to the MSSM Higgs doublet pair catalyze their vacuum expectation values. The Higgs and Higgsino-gaugino mass spectrum is presented for several choices of supersymmetry (SUSY) breaking and Higgs superpotential mass parameters. The additional vacuum expectation values provided by the constrained fields can produce a phenomenology quite different …
The discovery potential for the MSSM with heavy scalars at the LHC in the case of light inos is examined. We discuss the phenomenology of the model and the observables to determine the parameters. We show that for light gauginos, the model parameters can be constrained with a precision of the order of 15%.
We present a complete analysis of the one loop electroweak corrections to $e^-e^+\toγγ, ~Zγ, ~ZZ$ in the Standard (SM) and the Minimal Supersymmetric Standard Model (MSSM). Analytic expressions are written for the contributions to the helicity amplitudes. Several observables accessible for polarized or unpolarized beams and transverse, longitudinal or unpolarized final states are computed. We show that in the few hundred GeV region, these observables provide a test of the various SM or MSSM components. For the dominant TT amplitude at high energy, the sensitivity to the details of the various …
We reconsider constraints on $\cp$-violating phases in the Constrained Minimal Supersymmetric Standard Model. We include the recent calculations of Ibrahim and Nath on the chromoelectric and purely gluonic contributions to the quark electric dipole moment and combine cosmological limits on gaugino masses with experimental bounds on the neutron (and electron) electric dipole moments. The constraint on the phase of the Higgs mixing mass $μ$, $|\thm|$, is dependent on the value of the trilinear mass parameter, $A$, in the model and on $\tan β$. For values of $|A| < 300 \gev$ at the GUT scale, we …
Provided that Supersymmetry (SUSY) is realized, the Large Hadron Collider (LHC) and the future International Linear Collider (ILC) may provide a wealth of precise data from SUSY processes. An important task will be to extract the Lagrangian parameters. On this basis the goal is to uncover the underlying symmetry breaking mechanism from the measured observables. In order to determine the SUSY parameters, the program Fittino has been developed. It uses an iterative fitting technique and a Simulated Annealing algorithm to determine the SUSY parameters directly from the observables without any a p…
We calculate the predictions for lepton flavour violating (LFV) tau and muon decays, $l_j \to l_i γ$, $l_j \to 3 l_i$, $μ-e$ conversion in nuclei and LFV semileptonic tau decays $τ\to μPP$ with $PP= π^+π^-, π^0π^0, K^+K^-, K^0 {\bar K}^0$ $τ\to μP$ with $P=π^0, η, η'$ and $τ\to μV$ with $V = ρ^0, ϕ$, performing the hadronisation of quark bilinears within the chiral framework. We work within a SUSY-seesaw context where the particle content of the Minimal Supersymmetric Standard Model is extended by three right-handed neutrinos plus their corresponding SUSY partners, and where a seesaw mechanism…
We present predictions for $μ\to e γ$ and $τ\to μγ$ in the CMSSM in which there is a natural hierarchy of neutrino masses resulting from the sequential dominance of three right-handed neutrinos. We perform a global analysis of this model in the $(m_0,M_{1/2})$ plane, assuming radiative electroweak symmetry breaking, and including all observed laboratory data. We confirm that a large (small) $τ\to μγ$ rate results from the dominant right-handed neutrino being the heaviest (lightest) one. We show that the $μ\to e γ$ rate may determine the order of the sub-dominant neutrino Yukawa couplings in th…
Realistic predictions are made for the rates of lepton flavour violating Higgs boson decays, tau --> mu gamma, mu --> e gamma, Bs --> mu+mu-, Bs --> tau mu and tau --> 3mu, via a top-down analysis of the Minimal Supersymmetric Standard Model(MSSM) constrained by SU(5) unification with right-handed Neutrinos and large tan beta. The third family neutrino Yukawa coupling is chosen to be of order 1, in this way our model bares a significant resemblance to supersymmetric SO(10). In this framework the large PMNS mixings result in potentially large lepton flavour violation. Our analysis predicts tau …
We discuss a heterotic-string solution in which the observable sector effective field theory just below the string scale reduces to that of the MSSM, with the standard observable gauge group being just SU(3)_C x SU(2)_L x U(1)_Y and the SU(3)_C x SU(2)_L x U(1)_Y-charged spectrum of the observable sector consisting solely of the MSSM spectrum. Associated with this model is a set of distinct flat directions of vacuum expectation values (VEVs) of fields that all produce solely the MSSM spectrum. Some of these directions only involve VEVs of non-Abelian singlet fields while others also contain VE…
We study the quark flavor violating Higgs-boson decay $h \rightarrow \bar b s + b \bar s$ in the Minimal Supersymmetric Standard Model (MSSM). The decay is analyzed first in a model independent, and in a second step in the minimal flavor violationg (MFV) Constrained MSSM. The experimental constraints from $B$-Physics observables (BPO) and electroweak precision observables (EWPO) are also calculated and imposed on the parameter space. It is shown that in some cases the EWPO restrict the flavor violating parameter space stronger than the BPO. In the model independent analysis values of ${\cal O}…
We discuss the prospects for observing CP violation in the MSSM with six CP-violating phases, using a geometric approach to maximise CP-violating observables subject to the experimental upper bounds on electric dipole moments. We consider constraints from Higgs physics, flavour physics, the dark matter relic density and spin-independent scattering cross section with matter.
We obtain analytic formulae for the cross section of the sequential processes of $e^+ e^- \to t \bar t$ and $t \to b l ν$ in the laboratory frame where the dependence on triple product correlations of the type ($\hat(q}_1 x \hat{q}_2 . \hat{q}_3$), induced by CP violation both in the production and the decay are explicitely shown. Different observables sensitive to CP violation are defined and calculated in the Minimal Supersymmetric Standard Model (MSSM). The observables sensitive to CP violation are of the order of $10^-3$. The dependence on the masses of the supersymmetric particles is also…
We present the results of a first global fit to the electroweak observables in the MSSM. The best fit selects either very low or very large values of ~$\tanβ$ ~and, correspondingly, chargino (higgsino--like) and stop or the ~$CP-$odd Higgs boson are within the reach of LEP 2. Moreover, the best fit gives ~ $α_s(M_Z)=0.118^{+0.005}_{-0.010}$, ~which is lower than the one obtained from the SM fits. The overall fit is excellent ~ ($χ^2=7.2$ ~for 15 d.o.f. as compared to ~$χ^2=11$ ~in the SM). Those results follow from the fact that in the MSSM one can increase the value of ~ $R_b\equivΓ_{Z^0\to\b…
We study the μ\to e γdecay in the Z_3-invariant next-to-minimal supersymmetric (SUSY) Standard Model (NMSSM) with superheavy right-handed neutrinos. We assume that the soft SUSY breaking parameters are generated at the GUT scale, not universally as in the minimal supergravity scenario but in such a way that those soft parameters which are specific to the NMSSM can differ from the soft parameters which involve only the MSSM fields while keeping the universality at the GUT scale within the soft parameters for the MSSM and right-handed neutrino fields. We call this type of boundary conditions "se…
