Article

# Constraining the MSSM sfermion mass matrices with light fermion masses

(Impact Factor: 4.86). 02/2010; 81(7). DOI: 10.1103/PhysRevD.81.076001
Source: arXiv

ABSTRACT

We study the finite supersymmetric loop corrections to fermion masses and mixing matrices in the generic MSSM. In this context the effects of non-decoupling chirally-enhanced self-energies are studied beyond leading order in perturbation theory. These NLO corrections are not only necessary for the renormalization of the CKM matrix to be unitary, they are also numerically important for the light fermion masses. Focusing on the tri-linear A-terms with generic flavor-structure we derive very strong bounds on the chirality-changing mass insertions delta^{f\,LR,RL}_{IJ} by applying 't Hooft's naturalness criterion. In particular, the NLO corrections to the up quark mass allow us to constrain the unbounded element delta^{u\,RL}_{13} if at the same time $\delta^{u\,LR}_{13}$ is unequal to zero. Our result is important for single-top production at the LHC. Comment: 12 pages, 10 figures

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Available from: Jennifer Girrbach
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• "Since NA62 runs concurrently with the LHC, it is anyway useful to express ∆r µ−e in terms of the physical quantities probed in high-p T physics. Σ ℓ jR −ℓ iL is relevant for the W -coupling to leptons if j > i (and thus contributes to threshold corrections of the PMNS matrix as studied in Ref. [12] [28]), whereas for j < i Σ ℓ jR −ℓ iL is responsible for the correction of the charged-Higgs coupling. The charged-Higgs couplings to leptons Γ H + ℓ i ν ℓ j including an analytic resummation of tan β-enhanced corrections are listed in Eqs. "
##### Article: Gamma(K -> e nu)/Gamma(K -> mu nu) in the Minimal Supersymmetric Standard Model
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ABSTRACT: The quantity R_K = Gamma(K -> e nu)/Gamma(K -> mu nu) studied by the experiment NA62 at CERN is known to probe lepton-flavour violating (LFV) parameters of the Minimal Supersymmetric Standard Model (MSSM). A non-zero parameter delta_{RR}^{13} can open the decay channel K -> e nu_tau and enhance R_K over its Standard-Model value. In the region of the parameter space probed by NA62 the contribution from a bino-stau loop diagram is numerically dominant and the mixing between left-handed and right-handed staus is important. For large values of the stau mixing angle theta_tau the commonly adopted mass insertion approximation is not accurate. We therefore express the supersymmetric contribution to R_K in terms of the mass of the lightest stau eigenstate, the mixing angle theta_tau, and other relevant MSSM parameter such as tan(beta) and the charged-Higgs boson mass M_H and plot the parameter regions constrained by R_K. We further study to which extent R_K can be depleted through MSSM contributions interfering destructively with the SM amplitude for K -> e nu_e. This lepton-flavour conserving (LFC) mechanism involves the parameter combination |delta_{LL}^{13} delta_{RR}^{13}|, which can be constrained with a naturalness consideration for the electron mass or with the measurement of the anomalous magnetic moment of the electron. The LFC effect on R_K is marginal, an NA62 measurement of R_K significantly below the Standard Model expectation would indicate physics beyond the MSSM.
Preview · Article · Feb 2012
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##### Article: Lepton flavour violation in the MSSM
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ABSTRACT: We derive new constraints on the quantities δ XY ij , X, Y = L,R, which parametrise the flavour-off-diagonal terms of the charged slepton mass matrix in the MSSM. Considering mass and anomalous magnetic moment of the electron we obtain the bound $$\left| {\delta_{LL}^{13}\delta_{RR}^{{13}}} \right| \lesssim 0.{1}$$ for tan β = 50, which involves the poorly constrained element δ RR 13. We improve the predictions for the decays τ → μγ, τ → eγ and μ → eγ by including two-loop corrections which are enhanced if tan β is large. The finite renormalisation of the PMNS matrix from soft SUSY-breaking terms is derived and applied to the charged-Higgs-lepton vertex. We find that the experimental bound on BR(τ → eγ) severely limits the size of the MSSM loop correction to the PMNS element U e3, which is important for the proper interpretation of a future U e3 measurement. Subsequently we confront our new values for δ LL ij with a GUT analysis. Further, we include the effects of dimension-5 Yukawa terms, which are needed to fix the Yukawa unification of the first two generations. If universal supersymmetry breaking occurs above the GUT scale, we find the flavour structure of the dimension-5 Yukawa couplings tightly constrained by μ → eγ.
Full-text · Article · May 2010 · Journal of High Energy Physics
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##### Article: Flavor physics within and beyond the Standard Model
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ABSTRACT: I review recent progress in theoretical calculations related to the CKM unitarity triangle. After briefly discussing hints for new physics in B_d-B_d-bar mixing and B_s-B_s-bar mixing I present three topics of MSSM flavor physics: First I discuss new tan-beta-enhanced radiative corrections to flavor-changing neutral current (FCNC) amplitudes which go beyond the familiar Higgs-mediated FCNC diagrams and may enhance the mixing-induced CP asymmetry in B_d -> phi K_S. The second topic is a reappraisal of the idea that flavor violation originates from the soft supersymmetry-breaking terms. Finally I discuss how mu -> e gamma can be used to constrain the flavor structure of the dimension-5 Yukawa interactions which appear in realistic grand unified theories. Comment: 10 pages, talk at "Rencontres de Physique de la Vall\'ee d'Aoste", La Thuile, Italy, Feb 28 -- Mar 6, 2010
Preview · Article · Jun 2010