2,729 research outputs found

    Huge right-handed current effects in B->K*(K pi)l+l- in supersymmetry

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    Transverse asymmetries in the decay B->K*(K pi)l+l- are an extremely sensitive probe of right-handed flavour-changing neutral currents. We show how to include the contribution from the chiral partner of the electromagnetic operator on the transverse asymmetries at NLO in QCD factorization. We then consider supersymmetric models with non-minimal flavour violation in the down-squark sector. We include all the relevant experimental constraints and present a numerical formula for B->Xs gamma that takes into account the most recent NNLO calculations. We show that the flavour-changing parameters of these models are poorly constrained by present data and allow for large effects on the transverse asymmetries that we consider.Comment: 12 pages, 4 figures, version to appear on JHE

    Extended Minimal Flavour Violating MSSM and Implications for B Physics

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    The recently reported measurements of the CP asymmetry a(psi K) by the BABAR and BELLE collaborations are in good agreement with the standard model (SM) prediction, resulting from the unitarity of the CKM matrix. The so-called minimal flavour violating (MFV) supersymmetric extensions of the standard model, in which the CKM matrix remains the only flavour changing structure, predict a(psi K) similar to the one in the SM. With the anticipated precision in a(psi K) and other CP asymmetries at the B factories and hadron colliders, one hopes to pin down any possible deviation from the SM. We discuss an extension of the MFV-supersymmetric models which comfortably accommodates the current measurements of the CP asymmetry a(psi K), but differs from the SM and the MFV-supersymmetric models due to an additional flavour changing structure beyond the CKM matrix. We suggest specific tests in forthcoming experiments in B physics. In addition to the CP-asymmetries in B-meson decays, such as a(psi K) and a(pi pi), and the mass difference Delta M_s in the Bs-bar(Bs) system, we emphasize measurements of the radiative transition b -> d gamma as sensitive probes of the postulated flavour changing structure. Interestingly, the CKM-unitarity analysis in the Extended-MFV model also allows solutions rho < 0, as opposed to the SM and the MFV models for which only rho > 0 solutions are now admissible, implying gamma > pi/2, where gamma=- arg (Vub). Such large values of gamma are hinted by the current measurements of the branching ratios for the decays B -> pi pi and B -> K pi.Comment: 35 pages, 12 figures. Theoretical analysis modified in view of the recent CP violation observed in B-> J/Psi K decays. Resulting constraints on the model parameters are recompute

    Demise of CKM & its aftermath

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    Using firmly established experimental inputs such as epsilon_K, Delta M_d, Delta M_s, BR(B -> tau nu), gamma, V_cb along with corresponding lattice matrix elements which have been well studied and are in full QCD such as B_K, SU3 breaking ratio xi, B_Bs and in particular without using V_ub or the pseudoscalar decay constants f_Bd or f_Bs from the latice, we show that the CKM-paradigm now appears to be in serious conflict with the data. Specifically the SM predicted value of sin(2 beta) seems too high compared to direct experimental measured value by over 3 sigma. Furthermore, our studiy shows that new physics predominantly effects B-mixings and B_d -> psi K_s, and not primarily in kaon-mixing or in B -> tau nu. Model independent operator analysis suggests the scale of underlying new physics, accompanied by a BSM CP-odd phase, responsible for breaking of the SM is less than a few TeV, possibly as low as a few hundred GeV. Two possible BSM scenarios, namely warped extra-dimensions and SM with a 4th generation, are briefly discussed. Generic predictions of warped flavor models are briefly discussed. While SM with 4th generation (SM4) is a very simple way to account for the observed anomalies, SM4 is also well motivated due to its potential role in dynamical electrweak symmetery breaking via condensation of heavy quarks and in barygenesis.Comment: 18 pages, 8 figures, talk given at Moriond EW 2011, corrected typos in Fig.6 label

    Contributions of flavor violating couplings of a Higgs boson to pp→WWpp\to WW

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    We study contributions to pp→W+W−→ℓνℓℓ′νℓ′pp\to W^+W^- \to \ell\nu_\ell \ell^\prime\nu_{\ell^\prime} in models with a new Higgs boson, HH, and a neutral lepton, ν4\nu_{4}, with couplings H−ν4−νμH-\nu_{4}-\nu_{\mu} and W−ν4−μW-\nu_{4}-\mu through the process pp→H→ν4νμ→Wμνμ→ℓνℓμνμpp \to H \to \nu_4 \nu_\mu \to W \mu \nu_\mu \to \ell\nu_\ell \mu \nu_\mu. Contrary to naive expectations, we find that contributions to pp→WWpp\to WW can be very large while satisfying constraints from standard H→WWH\to WW and H→γγH\to\gamma\gamma searches. Even the excess observed by ATLAS in pp→WWpp\to WW, if taken at face value, can be easily accommodated. The various kinematic distributions fit nicely the experimentally determined ones. This scenario can arise for example in a two Higgs doublet model with vectorlike leptons.Comment: 16 pages, 5 figure
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