We present results of our study of tan(beta)-enhanced loop corrections in the Minimal Supersymmetric Standard Model (MSSM) with Minimal Flavour Violation (MFV). We demonstrate that these corrections induce flavour changing neutral current (FCNC) gluino couplings which have a large impact on the Wilson coefficient C_8 of the chromomagnetic operator. To illustrate the phenomenological consequences of this gluino-squark contribution to C_8, we briefly discuss its effect on the mixing-induced CP asymmetry in the decay B_d -> phi K_S.
I present results for the finite renormalization of the Cabibbo-Kobayashi-Maskawa (CKM) matrix induced by gluino--squark diagrams in the MSSM with non-minimal sources of flavour violation. Subsequently I derive bounds on the flavour--off--diagonal elements of the squark mass matrices by requiring that the radiative corrections to the CKM elements do not exceed the experimental values. The constraints on the associated dimensionless quantities $δ^{d LR}_{ij}$, $j>i$, are stronger than the bounds from flavour-changing neutral current (FCNC) processes if gluino and squarks are heavier than 500$ \…
In the supersymmetric models with nontrivial flavour structure in the soft-breaking sector the exchange of neutral Higgses mediates $ΔF=2$ transitions. This mechanism is studied for $ΔS, ΔB=2$ processes and for a generic form of the soft-breaking terms. We find that Higgs-mediated FCNC amplitudes increase very rapidly with $\tanβ$ and can exceed $SUSY$ box contribution by up to two orders of magnitude when $\tanβ\sim m_t/m_b$.
We consider FCNC and CP violating processes mediated by gluino exchange in generalized supersymmetric theories. We present the constraints on flavour (F) changing squark mass terms at the electroweak energy scale, focusing our analysis on $ΔF = 2$ transitions. Results are also given for $ΔF = 1$ CP conserving processes both in the hadronic and leptonic sectors, while we limit ourselves to some remarks on the relevance of box diagrams in the evaluation of $ε^{\prime}/ε$.
Recently it was shown, within the mass insertion approximation (MIA), that the gluino mediated flavor changing neutral current (FCNC) interactions can saturate both epsilon_K and Re(epsilon'/epsilon_K) even for the real Cabibbo-Kobayashi-Maskawa (CKM) matrix through a single CP violating parameter (delta^d_12)_LL. In this work, we extend our previous analysis to the nonvanishing KM phase, and to the effective SUSY model where the MIA is no longer a good approximation. In our model, epsilon_K and B0 - B0 bar mixing can receive significant SUSY contributions. Therefore the usual constraints on r…
Realistic predictions are made for lepton flavour violating and flavour changing neutral current decays in the large tan beta regime of a SUSY-seesaw model. Lepton flavour violating neutral Higgs decays are discussed within this framework along with the highly constraining charged lepton decays l_i --> l_j + gamma. In the b-s system the important constraint from b --> s + gamma is studied in conjunction with the rare FCNC Bs --> mu mu (tau mu) decays and the recently measured Delta Ms.
We compute the finite renormalisation of the Cabibbo-Kobayashi-Maskawa (CKM) matrix induced by gluino-squark diagrams in the MSSM with non-minimal sources of flavour violation. Subsequently we derive bounds on the flavour-off-diagonal elements of the squark mass matrices by requiring that the radiative corrections to the CKM elements do not exceed the experimental values. Our constraints on the associated dimensionless quantities delta^{d LR}_{ij}, j>i, are stronger than the bounds from flavour-changing neutral current (FCNC) processes if gluino and squarks are heavier than 500 GeV. Our bound …
Higgs singlet superfields are usually present in most extensions of the Minimal Supersymmetric Standard Model (MSSM) that address the mu-problem, such as the Next-to-Minimal Supersymmetric Standard Model (NMSSM) and the Minimal Nonminimal Supersymmetric Standard Model (MNSSM). Employing a gauge- and flavour-covariant effective Lagrangian formalism, we show how the singlet Higgs bosons of such theories can have significant contributions to B-meson flavour-changing neutral current (FCNC) observables for large values of $\tanβ\stackrel{>}{{}_\sim} 50$ at the 1-loop level. Illustrative results are…
We investigate two-loop gluino corrections to the effective Lagrangian for $b\to s+γ(g)$ in the minimal supersymmetric extension of the standard model (MSSM) at large $\tanβ$, including the contributions in which quark flavor change is mediated by charginos. Using the translation invariant of loop momenta and the Ward-Takahashi identities (WTIs) that are required by the $SU(3)_c\times U(1)_{_{em}}$ gauge invariance, we simplify our expressions to concise forms. As an example, we discuss two-loop gluino corrections to the CP asymmetry of inclusive $B\to X_{_s}γ$ decay in CP violating MSSM.
We derive the general resummed effective Lagrangian for Higgs-mediated flavour-changing neutral-current (FCNC) interactions in the Minimal Supersymmetric Standard Model (MSSM), without resorting to particular assumptions that rely on the squark-mass or the quark-Yukawa structure of the theory. In our derivation we also include the possibility of explicit CP violation through the Cabibbo--Kobayashi--Maskawa mixing matrix and soft supersymmetry-breaking mass terms. The advantages of our resummed FCNC effective Lagrangian are explicitly demonstrated within the context of phenomenologically motiva…
We study the FCNC top quark decays t -> c h in the framework of the MSSM, where h= h^0,H^0,A^0 is any of the supersymmetric neutral Higgs bosons. We include the leading set of SUSY-QCD and SUSY electroweak contributions. While the FCNC top quark decay into the SM Higgs boson has such a negligible rate that will not be accessible to any presently conceivable accelerator, we find that there is a chance that the potential rates in the MSSM can be measured at the high luminosity colliders round the corner, especially at the LHC and possibly at a future LC, but we deem it difficult at the upgraded …
Chirally enhanced supersymmetric QCD corrections to FCNC processes are investigated in the framework of the MSSM with generic sources of flavor violation. These corrections arise from flavor-changing self-energy diagrams and can be absorbed into a finite renormalization of the squark-quark-gluino vertex. In this way enhanced two-loop and even three-loop diagrams can be efficiently included into a leading-order (LO) calculation. Our corrections substantially change the values of the parameters delta^{d,LL}_{23}, delta^{d,LR}_{23}, delta^{d,RL}_{23}, and delta^{d,RR}_{23} extracted from Br[B->X_…
We study single top production at the LHC in a SUSY-QCD model with a heavy Dirac gluino. The presence of a heavy Dirac gluino allows for notable top-up flavour changing neutral currents. In this scenario, we find that the process ug->tg gives the largest contribution to single top production via FCNCs at the LHC. The key features of this signal are that the top quark is produced very forward and that it is asymmetric to its anti-top counterpart, as the latter lacks a valence quark.
Minimal $N=1$ supergravity with a radiatively broken electroweak symmetry group is studied in the light gluino scenario. Constraints from the $b\rightarrow sγ$ decay and from the masses of the light CP-even neutral Higgs $m_h$, the lightest chargino $m_{χ^{\pm}_1}$, and the second lightest neutralino $m_{χ^0_2}$ are analyzed. We consider models in which the relation $A=B+m_0$ holds. We plot the allowed region in the $\tanβ-μ$ plane consistent with chargino/neutralino searches, and an upper bound on $\tanβ$ given by 1.82 (1.85) for $μ>0$ ($μ<0$) is found. We analize the consistency of this uppe…
We present a MSSM study of the b -> s gamma decay in a Minimal Flavor Violating (MFV) framework, where the form of the soft SUSY breaking terms is determined by the Standard Model Yukawa couplings. In particular, we address the role of gluino contributions, which are set to zero in most studies of the MFV MSSM. Gluino contributions can play an important role in the MFV MSSM whenever mu * tan(beta) is large. In fact, similarly to chargino contributions, gluino contributions are tan(beta) enhanced and can easily dominate charged Higgs contributions for large values of tan(beta). Even though each…
Higgs singlet superfields, usually present in extensions of the Minimal Supersymmetric Standard Model (MSSM) which address the $μ$-problem, such as the Next-to-Minimal Supersymmetric Standard Model (NMSSM) and the Minimal Nonminimal Supersymmetric Standard Model (mnSSM), can have significant contributions to $B$-meson flavour-changing neutral current observables for large values of $\tanβ\gsim 50$. Illustrative results are presented including effects on the $B_s$ and on the rare decay $B_s\toμ^+μ^-$. In particular, we find that in the NMSSM, the branching ratio for $B_s\toμ^+μ^-$ can be enhanc…
The decay $b\to sν\barν$ is discussed in the minimal supersymmetric standard model with general flavor mixing for squarks, at large $\tanβ$. In this case, in addition to the chargino loop contributions which were analyzed in previously studies, $\tanβ$-enhanced contributions from the gluino and charged Higgs boson loops might become sizable compared with the standard model contribution, at least in principle. However, it is demonstrated that the experimental bounds on the new physics contributions to the radiative decay $b\to sγ$ should strongly constrain these contributions to $b\to sν\barν$,…
In light of the Higgs discovery and the nonobservation of sparticles at the LHC, we revisit the SUSY induced top quark flavor changing decay into the Higgs boson. We perform a scan over the relevant SUSY parameter space by considering the constraints from the Higgs mass measurement, the LHC search for SUSY, the vacuum stability, the precision electro-weak observables as well as $B \to X_s γ$. We have the following observations: (1) In the MSSM, the branching ratio of $ t \to c h$ can only reach $3.0\times10^{-6}$, which is about one order smaller than previous results obtained before the adven…
We study the Minimal Supersymmetric Standard Model with Minimal Flavour Violation for the case of a large parameter tanbeta and arbitrary values of the supersymmetric mass parameters. We derive several resummation formulae for tanbeta-enhanced loop corrections, which were previously only known in the limit of supersymmetric masses far above the electroweak scale. Studying first the renormalisation-scheme dependence of the resummation formula for the bottom Yukawa coupling, we clarify the use of the sbottom mixing angle in the supersymmetric loop factor Delta_b. As a new feature, we find tan-be…
Gluon mediated exclusive hadronic decays of b quarks are studied within the standard model (SM) and the constrained minimally supersymmetric standard model (MSSM). For all allowed regions of the MSSM parameter space (A, tan beta, m_0, m_{1/2}) the penguin magnetic dipole form factor F^R_2 is dominant over the electric dipole and can be larger than the magnetic dipole form factor of the SM. However, overall the SM electric dipole decay amplitude F^L_1 dominates the decay rate. The MSSM penguin contributions to the free quark decay rate approach the 10% level for those regions of parameter space…
We consider the Minimal Gauge Mediated Model (MGMM) with either fundamental or antisymmetric messenger multiplets and study consequences of messenger-matter mixing. It is shown that constraints on relevant coupling constants and mixing parameters coming from the existing experimental limits on lepton flavor violation and FCNC processes allow a wide range of $\tanβ$ in MGMM with mixing.
We present a solution to the $μ$ problem in an SO(10) supersymmetric grand unified (SUSY GUT) model with gauge mediated (GMSB) and D-term supersymmetry breaking. A Peccei-Quinn ({\bf PQ}) symmetry is broken at the messenger scale and enables the generation of the $μ$ term. The invisible axion (Goldstone boson of {\bf PQ} symmetry breaking) is a cold dark matter candidate. At low energy, our model leads to a phenomenologically acceptable version of the minimal supersymmetric standard model (MSSM) with novel particle phenomenology. Either the gluino or the gravitino is the lightest supersymmetri…
The charged-Higgs contributions to the decay \bar{B} -> X_s gamma are discussed in the minimal supersymmetric standard model at large tan beta. These contributions receive two-loop O(alpha_s tan beta) corrections by squark-gluino subloops, which are nondecoupling in the limit of heavy superpartners and possibly large. Their leading parts are already known and were evaluated by using an effective two-Higgs-doublet Lagrangian. Subleading corrections coming from higher-dimension operators in the effective Lagrangian were ignored, although this is not, a priori, justified when m_{H^\pm} is not muc…
We examine the process $B \to X_s γ$ in minimal supersymmetry (SUSY) with general squark flavor mixings. We include all relevant next--to--leading order (NLO) QCD corrections and dominant NLO SUSY effects from the gluino. We find that gluino--squark corrections to down--type quark masses induce large NLO corrections to the dominant Wilson coefficients whose size is often similar to those at LO, especially at large $\tanβ$. For $μ>0$, destructive interference, and suppression by the renormalization group running lead to a ``focusing effect'' of reducing the size of gluino corrections to the bra…
We present a detailed and complete calculation of the loop corrections to the mass difference $Δm_{B_d^0}/m_{B_d^0}$. We include charginos and scalar up quarks as well as gluinos and scalar down quarks on the relevant loop diagrams. We include the mixings of the charginos and of the scalar partners of the left and right handed quarks. We find that the gluino contribution to this quantity is important with respect to the chargino contribution only in a small part of phase space: mainly when the gluino mass is small ($\sim$ 100 GeV) and the symmetry-breaking parameter $m_S$ is below 300 GeV. Thi…
We show that LEPII will either discover charginos and neutralinos, or enable a very stringent upper limit to be placed on $\tan β$ as a function of the gluino mass. The only assumption we make is the existence of some unified model which breaks down to the minimal supersymmetric standard model below the unification scale. In such a framework we discuss how the discovery of a chargino at LEPII and the measurement of its mass and production cross-section, together with the measurement of the mass of the lightest neutralino, would enable the gluino mass, $\tan β$ and $μ$ to be predicted, up to a …
In the minimal supergravity model (mSUGRA), as the parameter $\tanβ$ increases, the charged Higgs boson and light bottom squark masses decrease, which can potentially increase contributions from $tH^\pm$, $\tg\tb_j$ and $\tz_i\tb_j$ loops in the decay $b\to sγ$. We update a previous QCD improved $b\to sγ$ decay calculation to include in addition the effects of gluino and neutralino loops. We find that in the mSUGRA model, loops involving charginos also increase, and dominate over $tW$, $tH^\pm$, $\tg\tq$ and $\tz_i\tq$ contributions for $\tanβ\agt 5-10$. We find for large values of $\tanβ\sim …
We investigate the potential effects of the scalar flavour changing neutral currents that are generated e.g. in supersymmetry with $\tanβ\gg1$ in the $b\to sl^+l^-$ transitions. Using the experimental upper limit on $BR(B^0_s\toμ^+μ^-)$ we place stringent model independent constraints on the impact these currents may have on the rates $BR(B\to X_sμ^+μ^-)$ and $BR(B\to Kμ^+μ^-)$. We find that in the first case, contrary to the claim made recently in the literature, the maximal potential effects are always smaller than the uncertainty of the Standard Model NNLO prediction, that is of order 5-15%…
The associated production of a Higgs boson with a b quark is a discovery mode for an MSSM Higgs boson at large tan beta. We compute the SUSY QCD corrections from gluino and squark loops to this process and combine them with the order alpha_s^2 NLO QCD corrections to obtain reliable predictions for the rate. Finally, we compare our results with an effective Lagrangian approximation which includes only the low energy corrections from squark and gluino loops to the b- bbar- Higgs vertices.
In this article we compute the two-loop SQCD corrections to Higgs-quark-quark couplings in the generic MSSM generated by diagrams involving squarks and gluinos. We give analytic results for the two-loop contributions in the limit of vanishing external momenta for general SUSY masses valid in the MSSM with general flavour-structure. Working in the decoupling limit (M_SUSY >> v) we resum all chirally enhanced corrections (related to Higgs-quark-quark couplings) up to order α_s^(n+1) tan(β)^n. This resummation allows for a more precise determination of the Yukawa coupling and CKM elements of the …
We present a complete next-to-leading order (NLO) calculation for the total cross section for inclusive Higgs pair production via bottom-quark fusion at the CERN Large Hadron Collider (LHC) in the minimal supersymmetric standard model (MSSM) and the minimal supergravity model (mSUGRA). We emphasize the contributions of squark and gluino loops (SQCD) and the decoupling properties of our results for heavy squark and gluino masses. The enhanced couplings of the b quark to the Higgs bosons in supersymmetric models with large tanb yield large NLO SQCD corrections in some regions of parameter space.
Although calculations of the $b\rightarrow sγ$ rate in supersymmetric grand unified models have always either ignored the gluino mediated contribution or found it to be negligible, we show that taking universal supersymmetry breaking masses at the Planck scale, rather than at the gauge unification scale as is customary, leads to the gluino contribution being more significant and in fact sometimes even larger than the chargino mediated contributions when $μ>0$ and $\tanβ$ is of order 1. The impact is greatest felt when the gluinos are relatively light. Taking the universal boundary condition at…
We apply the effective field theory definition of Minimal Flavour Violation (MFV) to the MSSM. We explicitly show how, by this definition, the new sources of flavour and CP violation present in the MSSM become functions of the SM Yukawa couplings, and cannot be simply set to zero, as is common wisdom in phenomenological MSSM studies that assume MFV. We apply our approach to the MSSM Delta B = 2 Hamiltonian at low tan(beta). The limit of MFV amounts to a striking increase in the predictivity of the model. In particular, SUSY corrections to meson-antimeson mass differences Delta M(d,s) are alway…
We present a general analysis of extensions of the Standard Model which satisfy the criterion of Minimal Flavour Violation (MFV). We define this general framework by constructing a low-energy effective theory containing the Standard Model fields, with one or two Higgs doublets and, as the only source of SU(3)^5 flavour symmetry breaking, the background values of fields transforming under the flavour group as the ordinary Yukawa couplings. We analyse present bounds on the effective scale of dimension-six operators, which range between 1 and 10 TeV, with the most stringent constraints imposed by…
We study the compatibility of a light bottom squark M_{\tilde b}< O(10 GeV) in the unconstrained MSSM. We consider the one-loop radiative corrections which are large for a heavy gluino (> O(150 GeV)). We then consider the renormalization group flow up to the Grand Unified scale. For most regions of the parameter space with a light sbottom we find colour and charge breaking minima. Only a small window in gluino mass and tan(beta) is consistent with all bounds. This is alleviated by a light gluino, which is however only marginally experimentally allowed.
We extend our previous analysis of the decays B_{d,s} -> mu^+ mu^- in the Minimal Supersymmetric Standard Model (MSSM) to include gluino and neutralino contributions. We provide analytic formulae, valid at large values of tan(beta), for the scalar and pseudoscalar Wilson coefficients arising from neutral Higgs boson exchange diagrams with gluinos and neutralinos. Together with the remaining contributions (W^{+/-}, H^{+/-}, charginos), and assuming the Cabibbo-Kobayashi-Maskawa (CKM) matrix to be the only source of flavour violation, we assess their implications for the branching fractions Br(B…
Grand Unified Theories predict relationships between the GUT-scale quark and lepton masses. Using new data in the context of the MSSM, we update the values and uncertainties of the masses and mixing angles for the three generations at the GUT scale. We also update fits to hierarchical patterns in the GUT-scale Yukawa matrices. The new data shows not all the classic GUT-scale mass relationships remain in quantitative agreement at small to moderate tan beta. However, at large tan beta, these discrepancies can be eliminated by finite, tan beta-enhanced, radiative, threshold corrections if the glu…
We examined the rare decays $B\to X_s\ell^+\ell^-$ and $B_s\to\ell^+\ell^-γ$ in the minimal supersymmetric model with large $\tanβ$. Taking into account the gluino-loop and neutralino-loop effects, we found that for a large $\tanβ$ the neutral Higgs exchanging diagrams could enhance $Br(B\to X_sτ^+τ^-)$ by a factor of 5 and $Br(B_s\toτ^+τ^-γ)$ by a couple of orders in some part of supersymmetric parameter space allowed by current experiments such as $b\to sγ, B\to K^{(*)}\ell^+\ell^-$ and $B_s\to\ell^+\ell^-$. The forward-backward asymmetry and the distributions of differential branching ratio…
We consider the infrared quasi fixed point solutions of the renormalization group equations for the Yukawa couplings and soft supersymmetry breaking parameters in the MSSM in the \underline{large $\tanβ$} regime. The existence of IR quasi fixed points together with the values of gauge couplings, third generation quarks, lepton and Z-boson masses allows one to predict masses of the Higgs bosons and SUSY particles as functions of the only free parameter, $m_{1/2}$, or the gluino mass. The lightest Higgs boson mass for $M_{SUSY} \approx 1$ TeV is found to be $m_h=128.2-0.4-7.1 \pm 5$ GeV for $μ>0…
The Electroweak sector in E6 supersymmetric models is subject to a degree of fine tuning in the percent to permil level. This can be attributed to the experimental limits on both the mass of the Z' boson associated with the extra U(1)' symmetry in the model, as well as the masses of naturalness-related sparticles (which is a general source of tuning in supersymmetric models). The degree of tuning can be smaller than that in the minimal supersymmetric standard model with universal fundamental parameters (the constrained MSSM). We show this by quantifying the fine tuning in regions of the parame…
We present SUSY_FLAVOR version 2.5 - a Fortran 77 program that calculates low-energy flavor observables in the general $R$-parity conserving MSSM. For a set of MSSM parameters as input, the code gives predictions for: 1. Electric dipole moments of the leptons and the neutron. 2. Anomalous magnetic moments (i.e. $g-2$) of the leptons. 3. Radiative lepton decays ($μ\to eγ$ and $τ\to μγ, eγ$). 4. Rare Kaon decays ($K^0_L\to π^0\barνν$ and $K^+\to π^+ \barνν$). 5. Leptonic $B$ decays ($B_{s,d}\to l^+ l^-$, $B\to τν$, $B\to D τν$ and $B\to D^\star τν$). 6. Radiative $B$ decays ($B\to\bar X_s γ$). 7…
The charged-Higgs boson contributions to the Wilson coefficients C_7 and C_8, relevant for the decay B -> X_s gamma, are discussed in supersymmetric models at large tan beta. These contributions receive two-loop O(alpha_s tan beta) corrections by squark-gluino subloops, which are possibly large and nondecoupling in the limit of heavy superpartners. In previous studies, the relevant two-loop Feynman integrals were approximated by using an effective two-Higgs-doublet lagrangian. However, this approximation is theoretically justified only when the typical supersymmetric scale M_SUSY is sufficient…
We present a calculation of the QCD correction factors $η_{2B}$ and $η_{2K}$ up to Next-to-Leading Order within the MSSM. We took into account the region of low $\tanβ$ for the Higgs- and chargino sector while neglecting the effect of gluinos and neutralinos.
We study the dependence on $\tanβ$ of the event kinematics of final states with $e^+e^- /μ^+μ^- /e^{\pm}μ^{\mp} + E_T^{\rm miss} + jets$, as expected in $pp$ collisions at CERN LHC, within the framework of the minimal supergravity model. With increase of $\tanβ$, the third generation sparticle masses $m_{\tildeτ_1}$ and $m_{\tilde{b}_1}$ decrease due to the increase of the tau and bottom Yukawa couplings. As a result, gluino, stop, sbottom, chargino and neutralino decays to third generation particles and sparticles are enhanced. With $\tanβ$ rising, we observe a characteristic change in the sh…
We analyse the mass spectrum of the Constrained Minimal Supersymmetric Standard Model at the low tan beta fixed point. We find that the model only satisfies experimental and dark matter bounds in regions where the vacuum is meta-stable -- ie where it violates `unbounded from below' (UFB) bounds. Adding a small amount of R-parity violation solves these problems but the absolute upper bound on the lowest higgs mass m_{h^0}<97 GeV remains. We present the predicted sparticle mass spectrum as a function of the gluino mass m_g.
We calculate the complete next-to-leading order QCD corrections to the three-body decay of gluino into top-pair associated with a lightest neutralino in the minimal supersymmetric standard model. We obtain that the LO and NLO QCD corrected decay widths of $\tilde{g} \to t \bar{t} \tildeχ_1^0$ at the ${\rm SPS 6}$ benchmark point are $0.1490 GeV$ and 0.1069 GeV respectively, and the relative correction is -28.2%. We investigate the dependence of the QCD correction to $\tilde{g} \to t \bar{t} \tildeχ_1^0$ on $\tanβ$ and the masses of gluino, scalar top quarks and the lightest neutralino around t…
Most of the existing analyses of FCNC processes in the 331 models, based on the gauge group SU(3)_C x SU(3)_L x U(1)_X, take only into account tree-level exchanges of a new heavy neutral gauge boson Z'. However due to the Z-Z' mixing also corresponding contributions from Z boson are present that are usually neglected. We calculate the impact of these contributions on Delta F=2 processes and rare K, B_s and B_d decays for different values of a parameter beta, which distinguishes between various 331 models and for different fermion representations under the SU(3)_L group. We find a general expre…
We present a general analysis of B_{s,d}-> l^+ l^- and K_L -> l^+ l^- decays in supersymmetric models with non-minimal sources of flavour mixing. In spite of the existing constraints on off-diagonal squark mass terms, these modes could still receive sizeable corrections, mainly because of Higgs-mediated FCNCs arising at large tan(beta). The severe limits on scenarios with large tan(beta) and non-negligible {tilde d}^i_{R(L)}-{d-tilde}^j_{R(L)} mixing imposed by the present experimental bounds on these modes and Delta B=2 observables are discussed in detail. In particular, we show that scalar-c…
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…
I present the contribution of gluinos and scalar quarks to the decay rate of the top quark into a charged Higgs boson and a bottom quark within the minimal supersymmetric standard model, including the mixing of the scalar partners of the left- and right-handed top quark. I show that for certain values of the supersymmetric parameters the standard QCD loop corrections to this decay mode are diminished or enhanced by several 10 per cent. I show that not only a small value of 3 GeV for the gluino mass (small mass window) but also much larger values of several hundreds of GeV's have a non-neglible…
Recent LHC data significantly extend the exclusion limits for supersymmetric particles, particularly in the jets plus missing transverse momentum channels. The most recent such data have so far been interpreted by the experiment in only two different supersymmetry breaking models: the constrained minimal supersymmetric standard model (CMSSM) and a simplified model with only squarks and gluinos and massless neutralinos. We compare kinematical distributions of supersymmetric signal events predicted by the CMSSM and anomaly mediated supersymmetry breaking (mAMSB) before calculating exclusion limi…
Pure leptonic and semileptonic rare B decays, $B_s \to μ^+ μ^-$ and $B \to X_s μ^+ μ^-$ in the minimal supersymmetric Standard Model (MSSM), in particular, gluino and neutralino contributions to the decays, are discussed under Br($B \to X_s γ$) and other experimental constraints . The general scalar quark mass matrices as the new sources of flavor violation are considered. We present Wilson coefficients of $bs$ transitions from $γ$, $Z$, and neutral Higgs boson penguin diagrams by using vertex mixing method to deal with scalar down-type quark flavor changing and also give their expressions in …
We perform a comprehensive study of the dominant two- and higher-loop contributions to the $^{205}$Tl, neutron and muon electric dipole moments induced by Higgs bosons, third-generation quarks and squarks, charginos and gluinos in the Minimal Supersymmetric Standard Model (MSSM). We find that strong correlations exist among the contributing CP-violating operators, for large stop, gluino and chargino phases, and for a wide range of values of $\tanβ$ and charged Higgs-boson masses, giving rise to large suppressions of the $^{205}$Tl and neutron electric dipole moments below their present experim…
The constraints imposed on the Minimal Supersymmetric Standard Model (MSSM) parameter space by the Large Hadron Collider (LHC) Higgs mass limit and gluino mass lower bound are revisited. We also analyze the thermal relic abundance of lightest neutralino, which is the Lightest Supersymmetric Particle (LSP). We show that the combined LHC and relic abundance constraints rule out most of the MSSM parameter space except a very narrow region with very large $\tan β~(\sim 50)$. Within this region, we emphasize that the spin-independent scattering cross section of the LSP with a proton is less than th…
Among the O(alpha_s tan beta) contributions to the Wilson coefficients C_7 and C_8, relevant for the decay bar{B} -> X_s gamma, those induced by two-loop diagrams with charged-Higgs-boson exchange and squark-gluino corrections are calculated in supersymmetric models at large tan beta. The calculation of the corresponding Feynman integrals is exact, unlike in previous studies that are valid when the typical supersymmetric scale M_SUSY is sufficiently larger than the electroweak scale m_weak (\sim m_W, m_t) and the mass of the charged Higgs boson m_{H^\pm}. Therefore, the results presented here …
Considering corrections from two-loop Feynman diagrams which involve gluino at large $\tanβ$, we analyze the effects of possible CP phases on the rare B decays: $\bar{B}_{_{s}} \to l^+l^-$ and $\bar{B}\to Kl^+l^-$ in the CP violating minimal supersymmetric extension of the standard model. It is shown that the results of exact two loop calculations obviously differ from that including one-loop contributions plus threshold radiative corrections. The numerical analysis indicates that the possibly large CP phases strongly affect the theoretical estimation of the branching ratios, and this results …
We compute the two-loop corrections of O(alpha_s^2) to the Yukawa couplings in the framework of the Minimal Supersymmetric Standard Model (MSSM). The calculation is performed using the effective Lagrangian approach under the approximation of neglecting the Higgs boson mass with respect to the top quark, gluino and all squark flavour masses. As an application we derive the O(alpha_s^2) corrections to the partial decay width of the lightest Higgs boson to a bottom quark pair. We find that the two-loop corrections are sizable for large values of tan_beta and low CP-odd Higgs boson mass. With our …
In this paper we explore the constraints from B-physics observables in SUSY models of Minimal Flavor Violation, in the large tan beta regime, for both low and high scale supersymmetry breaking scenarios. We find that the rare B-decays b -> s gamma and B_s -> mu+ mu- can be quite sensitive to the scale M at which supersymmetry breaking is communicated to the visible sector. In the case of high scale supersymmetry breaking, we show that the additional gluino contribution to the b -> s gamma and B_s -> mu+ mu- rare decay rates can be significant for large tan beta, mu and M_3. The constraints on …
We discuss B -> X_s gamma decay in both constrained and unconstrained supersymmetric models with explicit CP violation within the minimal flavor violation scheme by including tan(beta) -enhanced large contributions beyond the leading order. In this analysis, we take into account the relevant cosmological and collider bounds, as well as electric dipole moment constraints. In the unconstrained model, there are portions of the parameter space yielding a large CP asymmetry at leading order (LO). In these regions, we find that the CP phases satisfy certain sum rules, e.g., the sum of the phases of …
Supersymmetric loop contributions can lead to different decay rates of H+\to t\bar b and H-\to b\bar t. We calculate the decay rate asymmetry δ^CP = \frac{Γ(H+\to t\bar b)-Γ(H-\to b\bar t)}{{Γ(H+\to t\bar b)+Γ(H-\to b\bar t)} at next-to-leading order in the MSSM with complex parameters. We analyse the parameter dependence of δ^CP with emphasis on the phases of A_t and A_b. It turns out that the most important contribution comes from the loop with stop, sbottom, and gluino. If this contribution is present, δ^CP can go up to 10-15% for tan(beta)~10, and to ~5% for large values of tan(beta).
In this short note, we describe the preparation of updated templates for the interpretation of SUSY results from the LHC in the context of mSUGRA. The standard (m_0,m_{1/2}) plane is shown for fixed mu > 0 and m_t = 173.2 GeV. Two scenarios are considered: (1) A_0 = 0 GeV and tan(beta)=10 and (2) A_0 = -500 GeV and tan(beta)=40. In each case, the universal scalar mass parameter m_0 varies in the range [40,3000] GeV, while the universal gaugino mass parameter m_{1/2} varies in the range [100,1000] GeV. We delineate notable regions in parameter space, including the region with a charged LSP (sta…
