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提出了一种亚层子模型. 层子和轻子是由rishon T和V组成的. T和V是SUH(3)×SUC(3)×SUG(2)×U(1)群的多重态. 由这些多重态可以自然地得到三代层子和轻子. 在此模型中质子衰变为μ-e+e+或e-μ+μ+. 相似文献
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Using data samples collected at center-of-mass energies of √s=4.009, 4.230, 4.260, and 4.360 GeV with the BES0 detector operating at the BEPC/ collider, we perform a search for the process e+e-→γχc,j (J =0, 1, 2) and find evidence for e+e-→γχc1 and e+e-→γχc2 with statistical significances of 3.0σ and 3.4σ, respectively. The Born cross sections σB(e+e-→γχc,j), as well as their upper limits at the 90% con dence level (C.L.) are determined at each center-of-mass energy. 相似文献
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In this paper we study the semileptonic decays of Bc-→(ηc,J/Ψ)l-vl. We first evaluate the Bc→(ηc,J/Ψ) transition form factors F0(q2), F+(q2), V(q2) and A0,1,2(q2) by employing the pQCD factorization approach, and then we calculate the branching ratios for all considered semileptonic decays. Based on the numerical results and the phenomenological analysis, we find that: (a) the pQCD predictions for the values of the Bc→ηc and Bc→J/Ψ transition form factors agree well with those obtained by using other methods; (b) the pQCD predictions for the branching ratios of the considered decays are Br(Bc-→ηc e-ve(μ-vμ)=(4.41-1.09+1.22)×10-3, Br(Bc-→ηcτ-vτ) =(1.37-0.34+0.37)×10-3, Br(Bc-→J/Ψ e-ve(μ-vμ)) =(10.03-1.18+1.33)×10-3, and Br(Bc-→J/Ψτ-vτ) =(2.92-0.34+0.40)×10-3; and (c) we also define and calculate two ratios of the branching ratios Rηc and RJ/Ψ, which will be tested by LHCb and the forthcoming Super-B experiments. 相似文献
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本文用双核子机制及核矩阵元的有效算符理论讨论了在轻子数不守恒的0νββ衰变中的右手流. 从40Ca的0νββ衰变的实验寿命计算了右手流混合参量η, 及其和Majorana中微子质量mν之间的关系. 我们的计算给出: i)当|η|=0时, mν≤(18~23)eV;ii)当|η|≤(1.6~2)×10-5. 相似文献
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The recent measurements on RK and Rπ imply that there exists a possible violation of the leptonic flavor universality which is one of the cornerstones of the Standard Model. It is suggested that a mixing between sterile and active neutrinos might induce such a violation. In this work we consider the scenarios with one or two sterile neutrinos to explicitly realize the data while the constraints from the available experiments have been taken into account. Moreover, as indicated in literature, the deviation of the real PMNS matrix from the symmetric patterns may be due to a μ-τ asymmetry, therefore the measurements on RD(Ds)eμ=Γ(D(Ds)→ e+νe)/Γ(D(Ds)→ μ+νμ) and RD(Ds)μτ=Γ(D(Ds)→ μ+νμ)/Γ(D(Ds)→ τ+ντ) (and for some other heavy mesons B± and Bc etc.) may shed more light on the physics responsible for the violation of the leptonic flavor universality. The data of BESⅢ are available to test the universality and that of future charm-tau factories will provide more accurate information. In this work, we will discuss RD(Ds)eμ and RD(Ds)μτ in detail and also briefly consider the cases for B± and Bc. 相似文献
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本文利用重层子模型[1]中得到的介子B-S波涵数讨论介子的轻子型弱衰变、电磁衰变和各种二体强衰变过程. 除了解释fπ≈fK, 1-→l+l-等过程外, 计算得到的各种强衰变宽度也都同实验基本符合. 相似文献
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We discuss the production of ηc(2S) through the process e+e-→γηc(2S), where the leading contribution originates from 1-loop electroweak corrections. Adopting some reasonable light-cone distribution amplitudes, we analyze the cross section of this process. As the electron-positron center of mass energy √s=3770 MeV, the typical production cross section of this process is about 1 fb. 相似文献
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本文利用QCD的渐近自由性质,求出一条腿动量平方固定另一条腿动量平方趋于无穷大时的波函数,并把它应用于计算e++e-→π+q+(?)过程(其中π介子相对于层子喷注轴有大的横动量)。计算结果表明,这个过程对e++e-→强子截面的贡献比e++e-→g+q+(?)过程的贡献小得多。 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)+lν and Bs→Ds2(2573)+lν, 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 相似文献
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本文利用e+e-→重夸克jets中, 可分辨电磁激发与强作用产生的夸克的优点, 对后者的产生规律作了研究, 发现它产生的夸克对数满足一种简单普适规律, 由此算出的、i>多重数分布、前后关联等等都和实验符合、本文介绍了与的比较. 相似文献
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Motivated by the rst measurement on B(Bs→φμ+μ-) by the CDF Collaboration, we study the supersymmetric e ects in semi-leptonic Bs→φμ+μ- decay. In our evaluations, we analyze the dependences of the dimuon invariant mass spectrum and the forward-backward asymmetry on relevant supersymmetric couplings in the MSSM with and without R-parity. The analyses show that the new experimental upper limits of B(Bs→φμ+μ-)from the LHCb Collaboration could further improve the bounds on sneutrino exchange couplings and (δLLu)23 as well as (δLL,RRu)23 mass insertion couplings. In addition, within the allowed ranges of relevant couplings under the constraints from B(Bs→φμ+μ-), B(B→K(*)μ+μ-) and (Bs→φμ+μ-), the dimuon forward-backward asymmetry and the di erential dimuon forward-backward asymmetry of Bs→φμ+μ-are highly sensitive to the squark exchange contribution and the (δLLu)23 mass insertion contribution. The results obtained in this work will be very useful in searching for supersymmetric signals at the LHC. 相似文献
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本文假定e+e-湮没时产生的胶子的强子化,胶子首先劈裂成一对等效的夸克、反夸克对.夸克之间的色相互作用,碎裂成末态强子.由此计算的e+e-→3jet事例中的带电粒子多重数,胶子与夸克jet中多重数比率,以及e+e-三胶子事例中的重子比率,都与实验结果一致.解释了e+e-→3jet末态粒子的角分布. 相似文献
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We present a preliminary measurement of the B(Ds→μνμ) with the Belle 相似文献