The origin and the implications of higher dimensional effective operators in 4-dimensional theories are discussed in non-supersymmetric and supersymmetric cases. Particular attention is paid to the role of general, derivative-dependent field redefinitions which one can employ to obtain a simpler form of the effective Lagrangian. An application is provided for the Minimal Supersymmetric Standard Model extended with dimension-five R-parity conserving operators, to identify the minimal irreducible set of such operators after supersymmetry breaking. Among the physical consequences of this set of operators are the presence of corrections to the MSSM Higgs sector and the generation of "wrong"-Higgs Yukawa couplings and fermion-fermion-scalar-scalar interactions. These couplings have implications for supersymmetry searches at the LHC.
In a recent re-analysis of the Standard Model (SM) beta-function for the effective neutrino mass operator, we found that the previous results were not entirely correct. Therefore, we consider the analogous dimension five operators in a class of Two Higgs Doublet Models (2HDM's) and the Minimal Supersymmetric Standard Model (MSSM). Deriving the renormalization group equations for these effective operators, we confirm the existing result in the case of the MSSM. Some of our 2HDM results are new, while others differ from earlier calculations. This leads to modifications in the renormalization gro…
In the framework of the effective field theory approach to heavy supersymmetry radiative corrections in the Higgs sector of the Minimal Supersymmetric Standard Model (MSSM) for the effective potential decomposition up to the dimension-six operators are calculated. Symbolic expressions for the threshold corrections induced by $F$- and $D$- soft supersymmetry breaking terms are derived and the Higgs boson mass spectrum respecting the condition $m_h=$125 GeV for the lightest $CP$-even scalar is evaluated.
We study the effect of b to s sbar s scalar/pseudoscalar operators, originating from penguin diagrams of neutral Higgs bosons in the MSSM, in B to K eta(') and B to phi K^* decays. These operators can be Fierz-transformed into tensor operators, and the resultant tensor operators could affect the transverse polarization amplitudes in B to phi K^* decays. We find that only when the weak annihilations in B to phi K^* into account, the polarization puzzle can be resolved, so that new physics effects are strongly suppressed and no more relevant to the enhancement of the transverse modes in B to phi…
We continue a previous study of the MSSM Higgs Lagrangian extended by all effective operators of dimension d=6 that can be present beyond the MSSM, consistent with its symmetries. By supersymmetry, such operators also extend the neutralino and chargino sectors, and the corresponding component fields Lagrangian is computed onshell. The corrections to the neutralino and chargino masses, due to these operators, are computed analytically in function of the MSSM corresponding values. For individual operators, the corrections are small, of few GeV for the constrained MSSM (CMSSM) viable parameter sp…
Various aspects of the Higgs boson phenomenology of the Minimal Supersymmetric Standard Model (MSSM) are reviewed. Emphasis is put on the effects of higher-order corrections. The masses and couplings are discussed in the MSSM with real and complex parameters. Higher-order corrections to Higgs boson production channels at a prospective e+ e- linear collider are investigated. Corrections to Higgs boson decays to SM fermions and their phenomenological implications for hadron and lepton colliders are explored.
We study the implications of dimension five operators involving Higgs chiral superfields for the masses of neutralinos and charginos in the minimal supersymmetric standard model (MSSM). These operators can arise from additional interactions beyond those of MSSM involving new degrees of freedom at or above the TeV scale. In addition to the masses of the neutralinos and charginos, we study the sum rules involving the masses and squared masses of these particles for different gaugino mass patterns in presence of the dimension five operators in the context of MSSM. We derive a relation for the hig…
Including contributions of scale-dependent vacuum expectation values of Higgs scalars, we derive new one-loop formulas analytically for running quark-lepton masses at higher scales in MSSM. Apart from the gauge-coupling dependence being different from earlier formulas, the third-generation- Yukawa-coupling effects are absent in the masses of the first two generations. While predicting the masses and $\tanβ$ numerically, we also include two-loop effects.
The possibility of identification of an observable CMS $μ^+ μ^-$ excess at 28 GeV in the channel $pp\to μ^+ μ^- b \bar b$ at $\sqrt{s}$=8 TeV and 13 TeV as a manifestation of one of the minimal supersymmetric standard model (MSSM) Higgs bosons is investigated. The MSSM parametric scenarios in the regime of large threshold corrections involving low-mass CP-odd scalar, a 125 GeV CP-even scalar and other Higgs bosons with suitable masses are found, where the alignment limit conditions for the Higgs couplings are respected. Perturbative unitarity bounds and constraints on the electroweak vacuum st…
We study the effect of b to s sbar s scalar/pseudoscalar operators in B to K eta('), phi K^* decays. In the minimal supersymmetric standard model (MSSM), such scalar/pseudoscalar operators can be induced by the penguin diagrams of neutral Higgs bosons. These operators can be Fierz-transformed into tensor operators, and the resultant tensor operators could affect the transverse polarization amplitudes in B to phi K^* decays. A combined analysis of the decays B to phi K^* and B to K eta('), including b to s sbar s scalar/pseudoscalar operators and their Fierz-transformed tensor operators origina…
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…
We analyze the impact of the recent Feynman-diagrammatic (FD) two-loop results for the mass of the lightest CP-even Higgs boson in the MSSM on the theoretical upper bound for mh as a function of tan(beta). The results are compared with previous results obtained by renormalization group (RG) methods. The incorporation of dominant FD two-loop corrections into the decay width Γ(h -> f \bar f) is also discussed.
In this paper we discuss the production of a heavy scalar MSSM Higgs boson H and its subsequent decays into pairs of electroweak gauge bosons WW and ZZ. We perform a scan over the relevant MSSM parameters, using constraints from direct Higgs searches and several low-energy observables. We then compare the possible size of the pp -> H -> WW,ZZ cross sections with corresponding Standard Model cross sections. We also include the full MSSM vertex corrections to the H -> WW,ZZ decay and combine them with the Higgs propagator corrections, paying special attention to the IR-divergent contributions. W…
We interpret the current experimental limit on the lightest Higgs boson mass to suggest that if nature is supersymmetric, there are additional interactions beyond those of the MSSM coming from new degrees of freedom around the TeV scale. Within an effective field theory analysis, the leading order corrections to the MSSM are described in terms of only two operators. This provides a highly constrained description of Beyond MSSM (BMSSM) physics. The scalar Higgs spectrum as well as the chargino and neutralino spectrum and couplings are modified in a distinctive way. These operators can be genera…
We investigate the amount of fine tuning of the electroweak scale in the presence of new physics beyond the MSSM, parametrized by higher dimensional operators. We show that these significantly reduce the MSSM fine tuning to Delta<10 for a Higgs mass between the LEPII bound and 130 GeV, and a corresponding scale M_* of new physics as high as 30 to 65 times the Higgsino mass. If the fine-tuning criterion is indeed of physical relevance, the findings indicate the presence of new physics in the form of new states of mass of O(M_*) that generated the effective operators in the first instance. At sm…
We investigate an extension of the MSSM Higgs sector by including the effects of all dimension-five and dimension-six effective operators and their associated supersymmetry breaking terms. The corrections to the masses of the neutral CP-even and CP-odd Higgs bosons due to the d=5 and d=6 operators are computed. When the d=5 and d=6 operators are generated by the same physics (i.e. when suppressed by powers of the same scale M), due to the relative $\tanβ$ enhancement of the latter, which compensates their extra scale suppression (1/M), the mass corrections from d=6 operators can be comparable …
We perform a general analysis of the R-parity conserving dimension-five operators that can be present beyond the Minimal Supersymmetric Standard Model. Not all these operators are actually independent. We present a method which employs spurion-dependent field redefinitions that removes this "redundancy" and establishes the minimal, irreducible set of these dimension-five operators. Their potential effects on the MSSM Higgs sector are discussed to show that the tree level bound $m_h\leq m_Z$ cannot be easily lifted within the approximations used, and quantum corrections are still needed to sati…
We study the stability of the Higgs potential in the framework of the effective Lagrangian beyond the MSSM. While the leading nonrenormalizable operators can shift the Higgs boson mass above the experimental bound, they also tend to render the scalar potential unbounded from below. The destabilization is correlated with the Higgs mass increase, so that if quantum corrections are small the problem is severe. We show that a supersymmetric sub-leading correction stabilizes the potential within the domain of validity of the effective theory. Constraints on MSSM parameters as well as on higher dime…
We perform a detailed analysis of several mu-tau lepton flavour violating (LFV) processes, namely tau --> mu X (X = gamma, e+ e-, mu+ mu-, rho, pi, eta, eta'), Z --> mu tau and Higgs boson decays into mu tau. First we present a model independent operator analysis relevant to such decays, then we explicitly compute the LFV operator coefficients [and (g_μ-2)] in a general unconstrained MSSM framework, allowing slepton mass matrices to have large mu-tau entries. We systematically study the role and the interplay of dipole and non-dipole operators, showing how the rates and the mutual correlations…
We review an analysis of a consistent renormalization of the top and bottom quark/squark sector of the MSSM with complex parameters (cMSSM). Various renormalization schemes are defined, analyzed analytically and tested numerically in the decays Stop_2 -> Sbottom_i H^+/W^+ (i = 1,2). No scheme is found that produces numerically acceptable results over all the cMSSM parameter space, where problems occur mostly already for real parameters. Some numerical examples for Gamma(Stop_2 -> Sbottom_1 H^+) in our preferred scheme, "m_b, A_b DRbar" are shown.
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.
We discuss the $μ$-$e$ transition processes induced by non-holomorphic Yukawa interactions in the minimal supersymmetric standard model (MSSM). When supersymmetry is broken, the coupling structures between Higgs doublets and leptons are modified and flavor-changing neutral currents could be generated. In the framework of the MSSM, we calculate those effects to the rates for $\meg$, $\meee$, and $μ$-$e$ conversion in nuclei. We perform more detailed calculations of the lepton flavor violating (LFV) operators in the heavy Higgs decoupling limit than previous works, and show the accurate $\tanβ$ …
We present an analysis of non-leptonic B decays in the minimally flavour-violating MSSM with large tan(beta). We relate the Wilson coefficients of the relevant hadronic scalar operators to leptonic observables, showing that the present limits on the Bs->mu+ mu- and B+->tau nu_tau branching fractions exclude any visible effect in hadronic decays. We study the transverse helicity amplitudes of B->VV decays, which exhibit an enhanced sensitivity to the scalar operators, showing that even though an order one modification relative to the SM is not excluded in some of these amplitudes, they are too …
We discuss in detail a five-dimensional Minimal Supersymmetric Standard Model compactified on $S^1/Z_2$ extended by the effective Majorana neutrino mass operator. We study the evolution of neutrino masses and mixings. Masses and angles, in particular the atmospheric mixing angle $θ_{23}$, can be significantly lowered at high energies with respect to their value at low energy.
We construct a new minimal extension of the Minimal Supersymmetric Standard Model (MSSM) by promoting the $μ$-parameter to a singlet superfield. The resulting renormalizable superpotential is enforced by a $\mathcal{Z}_5$ $R$-symmetry which is imposed on the non-renormalizable operators as well. The proposed model provides a natural solution to the $μ$-problem and is free from phenomenological and cosmological problems.
In this contribution a brief review about the status of higher order corrections to Higgs boson production within the Minimal Supersymmetric Standard Model (MSSM) is given. Furthermore the first activities towards third-order corrections in the Standard Model (SM) are discussed.
Starting with the two-loop effective potential of the MSSM, and assuming a supersymmetric scale well above $M_Z$, we derive a simple analytical approximation for the lightest CP-even Higgs boson mass including resummation of higher order logarithmic terms via RG-improvement and finite non-logarithmic terms up to ${\cal O}(α_sα_t)$. This formula describes the most relevant radiative corrections to the MSSM Higgs boson mass, in particular, those associated with non-zero top-squark mixing.
An analysis of the electric dipole moment (EDM) of the neutron and of the leptons in the minimal supersymmetric standard model (MSSM) with the most general allowed set of CP violating phases without generational mixing is given. The analysis includes the contributions from the gluino, the chargino and the neutralino exchanges to the electric dipole operator, the chromoelectic dipole operator, and the CP violating purely gluonic dimension six operator. It is found that the EDMs depend only on certain combination of the CP phases. The independent set of such phases is classified. The analysis of…
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…
The corrections to the MSSM Higgs boson masses and couplings performed in this millennium are briefly reviewed. For the lightest MSSM Higgs boson mass, m_h, we list the current status of the intrinsic uncertainties (due to unknown higher-order corrections) and the parametric uncertainties (due to the imperfect experimental knowledge of the input parameters). The need for high-precision calculations in the MSSM Higgs boson sector is exemplified in a realistic example.
We present an update of neutral Higgs boson decays into bottom quark pairs in the minimal supersymmetric extension of the Standard Model. In particular the resummation of potentially large higher-order corrections due to the soft SUSY breaking parameters A_b and mu is extended. The remaining theoretical uncertainties due to unknown higher-order SUSY-QCD corrections are analyzed quantitatively.
We identify the bounds on supersymmetric effective operators beyond MSSM, from heavy diphoton resonance ($X$) negative searches at the LHC, where $X$ is identified with the neutral CP-even (odd) $H$ ($A$) or both (mass degenerate). While minimal supersymmetric models (MSSM, etc) comply with the data, a leading effective operator of $d=6$ can contribute significantly to diphoton production $σ\sim 1$ fb, well above its MSSM value and in conflict with recent data. Both the $b\bar b$ and $gg$ production mechanisms of $H$ and $A$ can contribute comparably to this. We examine the dependence of the d…
We analyze a scalar potential of the minimal supersymmetric standard model (MSSM) with neutrino mass operators along Unbounded-From-Below (UFB) and Color and/or Charged Breaking (CCB) directions. We show necessary conditions to avoid the potential minima which can be deeper than the realistic vacuum. These conditions would constrain more strongly than conditions in the MSSM without taking into account neutrino mass operators, and can improve the predictive power of supersymmetric models with neutrino mass operators.
We study the $B\to ϕK_S$ and $B\to \ep K_S$ decays in MSSM by calculating hadronic matrix elements of operators with QCD factorization approach and including neutral Higgs boson (NHB) contributions. We calculate the Wilson coefficients of operators including the new operators which are induced by NHB penguins at LO using the MIA with double insertions. We calculate the $α_s$ order hadronic matrix elements of the new operators for $B\to ϕK_s$ and $B\to η^\prime K_s$. It is shown that the recent experimental results on the time-dependent CP asymmetries in $B\to ϕK_S$ and $B\to \ep K_S$, $S_{ϕK}$…
We present the latest version 2.6 of FeynHiggs, a program for computing MSSM Higgs-boson masses and related observables, such as mixing angles, branching ratios, and couplings, including state-of-the-art higher-order contributions. The most important new feature is the inclusion of the fully complex O(α_tα_s) two-loop corrections, which enables FeynHiggs to give the most precise Higgs-mass evaluation in the complex MSSM in the Feynman-diagrammatic approach to date.
We present the fortran code SusyBSG version 1.1, which computes the branching ratio for the decay B -> Xs gamma in the MSSM with Minimal Flavor Violation. The computation takes into account all the available NLO contributions, including the complete supersymmetric QCD corrections to the Wilson coefficients of the magnetic and chromomagnetic operators.
The theoretical status of Higgs boson production at the LHC within the minimal supersymmetric extension of the Standard Model is reviewed. The focus will be on the evaluation of higher-order corrections to the production cross sections and their phenomenological implications.
We consider tan(beta)-enhanced quantum effects in the minimal supersymmetric standard model (MSSM) including those from the Higgs sector. To this end, we match the MSSM to an effective two-Higgs doublet model (2HDM), assuming that all SUSY particles are heavy, and calculate the coefficients of the operators that vanish or are suppressed in the MSSM at tree-level. Our result clarifies the dependence of the large-tan(beta) resummation on the renormalization convention for tan(beta), and provides analytic expressions for the Yukawa and trilinear Higgs interactions. The numerical effect is analyze…
In models with an extended Higgs sector, such as the (N)MSSM, scalar states mix with one another. Yet, the concept of Higgs mixing is problematic at the radiative level, since it introduces both a scheme and a gauge dependence. In particular, the definition of Higgs masses and decay amplitudes can be impaired by the presence of gauge-violating pieces of higher order. We discuss in depth the origin and magnitude of such effects and suggest two strategies preserving or restoring gauge invariance. In addition, the intuitive concept of mixing and the simplicity of its definition in terms of two-po…
When relating the strong coupling $α_s$, measured at the scale of the $Z$ boson mass, to its numerical value at some higher energy, for example the scale of Grand Unification, it is important to include higher order corrections both in the running of $α_s$ and the decoupling of the heavy particles. We compute the two-loop matching coefficients for $α_s$ within the Minimal Supersymmetric Standard Model (MSSM) which are necessary for a consistent three-loop evolution of the strong coupling constant. Different scenarios for the hierarchy of the supersymmetric scales are considered and the numeric…
We show that supersymmetric "new physics" beyond the MSSM can naturally accommodate a Higgs mass near 126 GeV and enhance the signal rate in the Higgs to diphoton channel, while the signal rates in all the other Higgs decay channels coincide with Standard Model expectations, except possibly the Higgs to Z-photon channel. The "new physics" that corrects the relevant Higgs couplings can be captured by two supersymmetric effective operators. We provide a simple example of an underlying model in which these operators are simultaneously generated. The scale of "new physics" that generates these ope…
We present several advances in the effective field theory calculation of the Higgs mass in MSSM scenarios with heavy superparticles. In particular, we compute the dominant two-loop threshold corrections to the quartic Higgs coupling for generic values of the relevant SUSY-breaking parameters, including all contributions controlled by the strong gauge coupling and by the third-family Yukawa couplings. We also study the effects of a representative subset of dimension-six operators in the effective theory valid below the SUSY scale. Our results will allow for an improved determination of the Higg…
We study electroweak baryogenesis and electric dipole moments in the presence of the two leading-order, non-renormalizable operators in the Higgs sector of the MSSM. Significant qualitative and quantitative differences from MSSM baryogenesis arise due to the presence of new CP-violating phases and to the relaxation of constraints on the supersymmetric spectrum (in particular, both stops can be light). We find: (1) spontaneous baryogenesis, driven by a change in the phase of the Higgs vevs across the bubble wall, becomes possible; (2) the top and stop CP-violating sources can become effective; …
We review recent progress towards automated higher-order calculations in the MSSM with complex parameters (cMSSM). The consistent renormalization of all relevant sectors of the cMSSM and the inclusion into the FeynArts/FormCalc framework has recently been completed. Some example calculations applying this framework are briefly discussed. These include two-loop corrections to cMSSM Higgs boson masses as well as partial decay widths of electroweak supersymmetric particles decaying into a Higgs boson and another supersymmetric particle.
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.
Including contributions of scale-dependent vacuum expectation values, we derive new analytic formulas and obtain substantially different numerical predictions for the running masses of quarks and charged-leptons at higher scales in the SM, 2HDM and MSSM. These formulas exhibit significantly different behaviours with respect to their dependence on gauge and Yukawa couplings than those derived earlier. At one-loop level the masses of the first two generations are found to be independent of Yukawa couplings of the third generation in all the three effective theories in the small mixing limit. Ana…
We provide a short account of the effects one expects on meson-antimeson oscillations in the context of the Minimal Supersymmetric Standard Model (MSSM). This issue is largely dependent on the assumptions made on the MSSM parameter space. In this respect, we consider in closer detail the cases of the general MSSM, with completely free soft terms, and the Minimal Flavor Violating limit of the MSSM, providing a natural mechanism of near-flavor-conservation. For the case of meson oscillations in the Delta B = 2 sector, we show that this approach leads to a striking increase of the predictivity of…
We review two systematic bottom-up analyses of MSSM quivers recently performed by the authors. We extend the analysis of arXiv:0905.3379 by including constraints arising from proton decay via dimension 5 operators and present all four-stack quivers in the Madrid embedding which satisfy this additional constraint. Furthermore, we investigate and make precise the interplay between mass hierarchies obtained via factorizable Yukawa textures and the presence of dimension 5 proton decay operators in MSSM orientifold compactifications. We discuss this issue in a five-stack quiver, first presented in …
We consider the QCD corrections to the electric dipole moment of the neutron in the Minimal Supersymmetric Standard Model. We provide a master formula for the Wilson coefficients at the low energy scale including for the first time the mixing between the electric and chromoelectric operators and correcting widely used previous LO estimates. We show that, because of the mixing between the electric and chromoelectric operators, the neutralino contribution is always strongly suppressed. We find that, in general, the effect of the QCD corrections is to reduce the amount of CP violation generated a…
We compute the complete supersymmetric QCD corrections to the Wilson coefficients of the magnetic and chromomagnetic operators, relevant in the calculation of b -> s gamma decays, in the MSSM with Minimal Flavor Violation. We investigate the numerical impact of the new results for different choices of the MSSM parameters and of the scale where the quark and squark mass matrices are assumed to be aligned. We find that the corrections can be important when the superpartners are relatively light, and that they depend sizeably on the scale of alignment. Finally, we discuss how our calculation can …
We apply the covariant derivative expansion of the Coleman-Weinberg potential to the sfermion sector in the minimal supersymmetric standard model, matching it to the relevant dimension-6 operators in the standard model effective field theory at one-loop level. Emphasis is paid to nondegenerate large soft supersymmetry breaking mass squares, and the most general analytical Wilson coefficients are obtained for all pure bosonic dimension-6 operators. In addition to the non-logarithmic contributions, they generally have another logarithmic contributions. Various numerical results are shown, in par…
We have studied the neutral Higgs boson (NHB) contributions to the pure penguin process $B\to ϕK_S$ in MSSM with middle and large $\tanβ$ (say, $>$ 8). We show that the $α_s$ order hadronic matrix elements of NHB induced operators can make sizable effects on both the branch ratio and time dependent CP asymmetry $S_{ϕK}$. Under the all relevant experimental constraints, the Higgs mediated contributions to $S_{ϕK}$ alone can provide a significant deviation from SM and, in particular, lead to a negative $S_{ϕK}$ which is reported by BaBar and Belle.
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.
FeynHiggs is a Fortran code for the calculation of the masses of the neutral CP-even Higgs bosons in the MSSM up to two-loop order. It is based on the complete diagrammatic on-shell results at the one-loop level, the leading diagrammatic two-loop QCD contributions and further improvements taking into account leading electroweak two-loop and leading higher-order QCD corrections. The Higgs-boson masses are calculated as functions of the MSSM parameters for general mixing in the scalar top sector and arbitrary choices of the parameters in the Higgs sector of the model.
We evaluate O(alpha_b alpha_s) corrections in the MSSM Higgs boson sector, including an analysis of the renormalization in the bottom/scalar bottom sector. For mu < 0 the genuine two-loop corrections to the mass of the lightest Higgs boson mass can amount up to 3 GeV. Different renormalization schemes are applied and numerically compared. Likewise the residual dependence on the renormalization scale is investigated. This allows to determine the remaining theoretical uncertainties from unknown higher-order corrections at O(alpha_b alpha_s^2) for different regions of the MSSM parameter space.
We present a construction kit for calculating two-loop beta functions in N=1 supersymmetric theories for the operators of the superpotential using supergraph techniques. In particular, it allows to compute the beta functions for every desired, even higher dimensional, operator of the superpotential from the wavefunction renormalization constants of the theory. We apply this method to calculate the two-loop beta functions for the lowest-dimensional effective neutrino mass operator in the Minimal Supersymmetric Standard Model (MSSM) and for the Yukawa couplings in the MSSM extended by singlet su…
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.
We report on a calculation of the effects of supersymmetry on the cross-section for top-antitop production at LHC. A numerical study is carried out for the ten benchmarks of the Snowmass accord. It is found that the higher order effects involving supersymmetric particles in internal loops can be as high as 6%, both for the cross-section and the (parity even) helicity asymmetry, for one particular benchmark. For other benchmarks smaller but nonetheless observable corrections are found.
Scalar MSSM Higgs boson production via gluon fusion gg -> h,H is mediated by heavy quark and squark loops. The higher order QCD corrections to these processes turn out to be large. The full supersymmetric QCD corrections have been calculated recently. In the limit of large SUSY masses a conceptual problem appears, i.e. the proper treatment of the large gluino mass limit. In this work we will describe the consistent decoupling of heavy gluino effects and derive the effective Lagrangian for decoupled gluinos.
We discuss Higgs boson decays in the CP-violating MSSM, and examine their phenomenological impact using cross section limits from the LEP Higgs searches. This includes a discussion of the full 1-loop results for the partial decay widths of neutral Higgs bosons into lighter neutral Higgs bosons (h_a -> h_b h_c) and of neutral Higgs bosons into fermions (h_a -> f fbar). In calculating the genuine vertex corrections, we take into account the full spectrum of supersymmetric particles and all complex phases of the supersymmetric parameters. These genuine vertex corrections are supplemented with Hig…
In the Minimal Supersymmetric Standard Model (MSSM) with three generations of fermions, there is a stringent upper bound on the mass of the lightest neutral Higgs h, and the mass of the charged Higgs H^+, must be close (within tens of GeV) to the heavier neutral Higgs, H, and the pseudoscalar Higgs A. In this Brief Report, we show that in the four generation MSSM, the upper bound on the h mass is much higher, as high as 400 GeV, and H^+ is generally much heavier than the A, allowing the H^+ -> A W^+ decay, potentially changing search strategies for both the charged Higgs and the pseudoscalar. …
