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1.
Lepton number violation processes can be induced by the Majorana neutrino exchange, which provide evidence for the Majorana nature of neutrinos. In addition to the natural explanation of the small neutrino masses,Type-I seesaw mechanism predicts the existence of Majorana neutrinos. The aim of this work is to study the B meson rare decays B~+→K~((*))+μ~+μ~-in the Standard Model and its extensions, and then to investigate the same-sign decay process B~+→K~((*)-)μ~+μ~+. The corresponding dilepton invariant mass distributions are calculated. It is found that the dilepton angular distributions could shed light on the properties of new interactions induced by Majorana neutrinos. 相似文献
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《中国物理C(英文版)》2010,(9)
Based on a data sample of 384 million BB pairs collected with the BABAR detector at the PEP-Ⅱ asymmetric e + e  ̄ storage ring,we measure branching fractions,direct CP,isospin and lepton-flavor asymmetries for the rare decays B → K (*) l + l ̄ in two di-lepton mass bins above and below the J/ψ resonance.For the B → K* l + l ̄ decay,we also measure the K* longitudinal polarization fraction and the di-lepton forwardbackward asymmetry. 相似文献
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Recently, the first evidence for the decay B s 0 → μ + μ ? has been announced by the LHCb Collaboration and the measured branching ratio B( s 0 → μ +) = (3.2 ?1.2 +1.5 ) × 10?9 is in good agreement with the standard model (SM) expectation. It has also reported an upper limit for B(B d 0 → μ + μ ?) < 9.4 × 10?10 at 95% confidence level. In this paper, we study the B s 0 → μ + μ ? and B d 0 → μ + μ ? rare decays in flavor-changing Z′ model. Our estimated branching ratios are enhanced from their SM values and provide signals for new physics. 相似文献
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The observation potential of the decay B+ K+K+– with the ATLAS detector at LHC is described in this paper. In the Standard Model this decay mode is highly suppressed, while in models beyond the Standard Model it could be significantly enhanced. To improve the selection of the K+K+– final state, a charged hadron identification using Time-over-Threshold measurements in the ATLAS Transition Radiation Tracker was developed and used. 相似文献
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Gautam Bhattacharyya 《Pramana》2009,72(1):37-54
In this talk, I shall first discuss the Standard Model Higgs mechanism and then highlight some of its deficiencies making
a case for the need to go beyond the Standard Model (BSM). The BSM tour will be guided by symmetry arguments. I shall pick
up four specific BSM scenarios, namely, supersymmetry, little Higgs, gauge-Higgs unification, and the Higgsless approach.
The discussion will be confined mainly on their electroweak symmetry breaking aspects.
相似文献
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We invesdgate the correction to the branching ratio of decay b→sγ from the Pseudo-Goldstone bosons (PGBs) in the multiscale walking technicolor model (MWTCM). Tbe correction is found so large that we can not explain the recentCLEO data lf topcolor is further introduced. the branching ratio in the topcolor assisted MWTCM will be in agreement with the CLEO data for a certain range of the model-allowed parameter space. 相似文献
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Based on a data sample of 384 million BB pairs collected with the BABAR detector at the PEP-Ⅱ asymmetric e + e  ̄ storage ring,we measure branching fractions,direct CP,isospin and lepton-flavor asymmetries for the rare decays B → K (*) l + l ̄ in two di-lepton mass bins above and below the J/ψ resonance.For the B → K* l + l ̄ decay,we also measure the K* longitudinal polarization fraction and the di-lepton forwardbackward asymmetry. 相似文献
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Physics of Atomic Nuclei - The authors within the Higgs Boson Working Group of the ATLAS experiment at the LHC performed an analysis of events with two leptons and two hadron jets to study Standard... 相似文献
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The helicity amplitudes for J/ψ→Λ■ and the relevant background decays are presented for measuring the ■ decay parameter α (■→π ) in J/ψ→Λ■. The Monte Carlo (MC) simulations based on the helicity amplitudes information are carried out. The likelihood fit method to determine the ■ decay parameter is presented. Based on the MC generated sample, the sensitivity of the measurement for α has been estimated, which shows that the J/ψ→Λ■ channel can be used to measure the ■ decay parameter α (■→π ) well. 相似文献
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During the past few years,signs of lepton flavor universality(LFU)violation have been observed in b→cτ■ and b→sl+l-transitions.Recently,the D* and τ polarization fractions P_L~D* and P_L~τ in B→D*τ■decay were likewise measured by the Belle collaboration.Motivated by these intriguing results,we revisit the RD(*)and RK(*) anomalies in a scalar leptoquark(LQ)model,where two scalar LQs,one of which is a S U(2)L singlet and the other a S U(2)L triplet,are introduced simultaneously.We consider five b→ cτ■ mediated decays,B→D(*)τ■,B_c→ηcτ■,Bc→J/ψt■,and ∧_b→∧_cτ■,and focus on the LQ effects on the q~2 distributions of the branching fractions,LFU ratios,and various angular observables in these decays.Under the combined constraints of the available data on RD(*),RJ/ψ,P_L~τ(D*),and pLD*,we perform scans for the LQ couplings and make predictions for a number of observables.Numerically it is found that both the differential branching fractions and LFU ratios are largely enhanced by the LQ effects,with the latter expected to provide testable signatures at the SuperKEKB and High-Luminosity LHC experiments. 相似文献
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The decay t→cV(V=γ,Z,g)processes in mirror twin Higgs models with colorless top partners are studied in this paper.We report that the branchi ng ratios of these decays can strongly affect the standard model expectations in some parameter spaces and may be detectable according to the current precision electroweak measurements.Thus,constraints on the model parameters may be obtained from the branching fraction of the decay processes,which may serve as a robust detection tool for this new physics model. 相似文献
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We consider the effects of the fourth generation quarks on the rare B decay processes described by the b → s(d)ννˉ processes at the quark level.We find that the values of the branching ratios for some of these rare decay processes are much larger than the standard model(SM) predictions.These processes can be used to constrain the relevant free parameters. 相似文献
14.
DIPTIMOY GHOSH 《Pramana》2012,79(4):895-898
A comprehensive study of the impact of new-physics operators with different Lorentz structures on decays involving the b ?? s ?? ?+? ?? ? transition is performed. The effects of new vector?Caxial vector (VA), scalar?Cpseudoscalar (SP) and tensor (T) interactions on the differential branching ratios, forward?Cbackward asymmetries (A FB??s), and direct CP asymmetries of ${\bar B}_{\rm s}^0 \to \mu^+ \mu^-$ , ${\bar B}_{\rm d}^0 \to$ $ X_{\rm s} \mu^+ \mu^-$ , ${\bar B}_{\rm s}^0 \to \mu^+ \mu^- \gamma$ , ${\bar B}_{\rm d}^0 \to {\bar K} \mu^+ \mu^-$ , and ${\bar B}_{\rm d}^0\to {\bar{K}^*} \mu^+ \mu^-$ are examined. In ${\bar B}_{\rm d}^0\to {\bar{K}^*} \mu^+ \mu^-$ , we also explore the longitudinal polarization fraction f L and the angular asymmetries $A_{\rm T}^{(2)}$ and A LT, the direct CP asymmetries in them, as well as the triple-product CP asymmetries $A_{\rm T}^{\rm (im)}$ and $A^{\rm (im)}_{\rm LT}$ . While the new VA operators can significantly enhance most of the observables beyond the Standard Model predictions, the SP and T operators can do this only for A FB in ${\bar B}_{\rm d}^0 \to {\bar K} \mu^+ \mu^-$ . 相似文献
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《Solid State Communications》1986,57(2):129-131
The hybrid potential method developed earlier is employed to study the electronic structure of Na in rare gas solids. The Jahn-Teller coupling coefficient for the 3p state and hence the splitting of the 3s→3p transition are calculated. The reuslts are in satisfactory agreement with experiment, and support the Jahn-Teller model for the triplet structure observed in the absorption spectra. 相似文献
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Based on the assumption that Ds1(2536) and Ds2(2573) belong to T doublet (1 ,2 ), we calculate the semileptonic decays of Bs to Ds1(2536) and Ds2(2573) in terms of the Constituent Quark Meson (CQM) model. For Bs → Ds1(2536) l, and Bs → Ds2(2573) l, the order of magnitude of the obtained branching ratios is 10-3. Our numerical results of the semileptonic decays of Bs to Ds1(2536) and Ds2(2573) are large, which implies that two semileptonic decays should be seen in future experiments. 相似文献