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Register a new userMuon g-2 through a flavor structure on soft SUSY terms
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F.V. Flores-Baez
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In this work we analyze the possibility to explain the muon anomalous magnetic moment discrepancy within theory and experiment through lepton flavor violation processes. We propose a flavor extended MSSM by considering a hierarchical family structure for the trilinear scalar Soft-Supersymmetric terms of the Lagranagian, present at the SUSY breaking scale. We obtain analytical results for the rotation mass matrix, with the consequence of having non-universal slepton masses and the possibility of leptonic flavour mixing. The one-loop supersymmetric contributions to the leptonic flavour violating process $tau to mugamma$ are calculated in the physical basis, with slepton flavour mixed states, instead of using the well known Mass Insertion Method. We present the regions in parameter space where the muon g-2 problem is either entirely solved or partially reduced through the contribution of these flavor violating processes.
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We propose a SUSY scenario to explain the current electron and muon $g-2$ discrepancies without introducing lepton flavor mixings. Threshold corrections to the Yukawa couplings can enhance the electron $g-2$ and flip the sign of the SUSY contributions. The mechanism predicts a flavor-dependent slepton mass spectrum. We show that it is compatible with the Higgs mediation scenario.
We discuss gauge mediated supersymmetry breaking models which explain the observed muon anomalous magnetic moment and the Higgs boson mass simultaneously. The successful explanation requires the messenger sector which violates the relation motivated by the grand unification theory (GUT). The naive violation of the GUT relation, however, ends up with the CP problem. We propose a model in which the phases of the gaugino masses are aligned despite the violation of the GUT relation. We also consider a model which generates the $mu$-term and the additional Higgs soft masses squared without causing CP violation. As a result, we find a successful model which explains the muon anomalous magnetic moment and the Higgs boson mass. The model is also free from the CP, flavor-changing neutral current and the lepton flavor violation problems caused by the subdominant gravity mediation effects.
A systematic investigation on muon anomalous magnetic moment and related lepton flavor-violating process such as $mto eg$, $tto eg$ and $tto mg$ is made at two loop level in the models with flavor-changing scalar interactions. The two loop diagrams with double scalar exchanges are studied and their contributions are found to be compatible with the ones from Barr-Zee diagram. By comparing with the latest data, the allowed ranges for the relevant Yukawa couplings $Y_{ij}$ in lepton sector are obtained. The results show a hierarchical structure of $Y_{m e, t e} ll Y_{m t} simeq Y_{mm}$ in the physical basis if $Delta a_{mu}$ is found to be $>50times 10^{-11}$. It deviates from the widely used ansatz in which the off diagonal elements are proportional to the square root of the products of related fermion masses. An alternative Yukawa coupling matrix in the lepton sector is suggested to understand the current data. With such a reasonable Yukawa coupling ansatz, the decay rate of $tto mg$ is found to be near the current experiment upper bound.
We examine several issues pertaining to statistical predictivity of the string theory landscape for weak scale supersymmetry (SUSY). We work within a predictive landscape wherein super-renormalizable terms scan while renormalizable terms do not. We require stringy naturalness wherein the likelihood of values for observables is proportional to their frequency within a fertile patch of landscape including the MSSM as low energy effective theory with a pocket-universe value for the weak scale nearby to its measured value in our universe. In the string theory landscape, it is reasonable that the soft terms enjoy a statistical power-law draw to large values, subject to the existence of atoms as we know them (atomic principle). We argue that gaugino masses, scalar masses and trilinear soft terms should each scan independently. In addition, the various scalars should scan independently of each other unless protected by some symmetry. The expected non-universality of scalar masses-- once regarded as an undesirable feature-- emerges as an asset within the context of the string landscape picture. In models such as heterotic compactifications on Calabi-Yau manifolds, where the tree-level gauge kinetic function depends only on the dilaton, then gaugino masses may scale mildly, while scalar masses and A-terms, which depend on all the moduli, may scale much more strongly leading to a landscape solution to the SUSY flavor and CP problems in spite of non-diagonal Kahler metrics. We present numerical results for Higgs and sparticle mass predictions from the landscape within the generalized mirage mediation SUSY model and discuss resulting consequences for LHC SUSY and WIMP dark matter searches.
The recent confirmation of the muon $g-2$ anomaly by the Fermilab g-2 experiment may harbinger a new era in $mu$ and $tau$ physics. As is known, the effect can arise from one-loop exchange of sub-TeV exotic scalar and pseudoscalars, namely $H$ and $A$, that have flavor changing neutral couplings $rho_{taumu}$ and $rho_{mutau}$ at $sim 20$ times the usual tau Weinberg coupling, $lambda_tau$. A similar diagram induces $mu to egamma$, where $rho_{etau}= rho_{tau e} = {cal O}(lambda_e)$ brings the rate right into the sensitivity of the MEG II experiment, and the $mu egamma$ dipole can be probed further by $mu to 3e$ and $mu N to eN$. With its promised sensitivity range and ability to use different nuclei, the $mu N to e N$ conversion experiments can not only make discovery, but access the extra diagonal quark Weinberg couplings $rho_{qq}$. For the $tau$ lepton, $tau to mugamma$ would probe $rho_{tautau}$ down to $lambda_tau$ or lower, while $tau to 3mu$ would probe $rho_{mumu}$ to ${cal O}(lambda_{mu})$.
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