丰中子氮同位素β-衰变的理论研究

使用壳模型系统地研究了丰中子氮同位素的β^-衰变,并对其衰变子核^18,19,20,21O的能级结构性质给出理论计算,所得结果与实验符合较好.研究了^18,19,20N核的Gamow-Teller允许型β^-衰变的特性,对与近期实验观测不一致之处进行了讨论和分析.预言了²¹N的β^-衰变及其子核高激发态的能级结构性质.这些计算将对氮同位素的实验研究很有帮助. 关键词： 中子滴线 -衰变')" href="#">β^-衰变 氮同位素 壳模型     

Bi同位素链上原子核α衰变性质的理论研究

采用结团模型(clustermodel)计算了从10752Te到292116共443个核素α衰变的半衰期,所得结果与实验值符合得很好,显示了结团模型可以成功地应用于研究原子核α衰变的性质。同时研究了Bi同位素链上奇A核α衰变的半衰期,计算结果与已有的实验值的偏差一般在3倍以内,进而对实验上未知α衰变半衰期的原子核的性质进行了预言。这有助于将来在实验室探测与鉴别这些原子核以及研究它们的α衰变性质。理论与实验的比较将加深人们对原子核结构的认识。     

Search for new physics in the B→K^（＊）l^＋l^- decays at BABAR

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.     

Two loop electroweak corrections from heavy fermions to b→s＋γ

Applying an effective Lagrangian method and an on-shell scheme, we analyze the electroweak corrections to the rare decay b→, s＋γ from some special two loop diagrams in which a closed heavy fermion loop is attached to the virtual charged gauge bosons or Higgs. At the decoupling limit where the virtual fermions in the inner loop are much heavier than the electroweak scale, we verify the final results satisfying the decoupling theorem explicitly when the interactions among Higgs and heavy fermions do not contain the nondecoupling couplings. Adopting the universal assumptions on the relevant couplings and mass spectrum of new physics, we find that the relative corrections from those two loop diagrams to the SM theoretical prediction on the branching ratio of B → Xsγ can reach 5% as the energy scale of new physics ANp=200 GeV.     

Hadron molecules

We discuss a possible interpretation of the open charm mesons D＊s0 （2317）,D s1 （2460） and the hidden charm mesons X（3872）,Y（3940） and Y（4140） as hadron molecules.Using a phenomenological Lagrangian approach we review the strong and radiative decays of the D＊ s0 （2317） and D s1 （2460） states.The X（3872） is assumed to consist dominantly of molecular hadronic components with an additional small admixture of a charmonium configuration.Determing the radiative （γJ/ψ and γψ（2s）） and strong （J/ψ2π and J/ψ3π） decay modes we show that the present experimental observation is consistent with the molecular structure assumption of the X（3872）.Finally,we give evidence for molecular interpretations of the Y（3940） and Y（4140） related to the observed strong decay modes J/ψ＋ω or J/ψ＋φ,respectively.     

Charm hadronic decays and quantum correlations at CLEO-c

Several recent CLEO-c results on hadronic decays of charm mesons are reviewed. Topics include measurements of precision branching fractions for exclusive modes, investigations of inclusive rates, and analyses of Dalitz plots. In addition, the quantum correlations of the DD pairs produced at the ψ（3770） are exploited to measure phase information that is of current interest for both D and B physics.     

D^0-D^0 mixing and other charm decays at Belle

The D^0-D^0 mixing at Belle in different modes with corresponding methods is reported in this paper, there is a clear evidence for non-zero y D^0 mixing parameter, and the measurement of D^0 mixing parameter x is still a challenge. CP violation in the decays is not observed. Branching fractions of other charm decays are presented.     

Semileptonic bc to cc and bb to bc baryon decays and heavy quark spin symmetry

We study the semileptonic decays of the lowest-lying bc baryons to the lowest-lying cc baryons （Ξ （＊） bc → Ξ （＊） cc and Ω （ ＊） bc → Ω （＊） cc ）,in the limit m b,m c Λ QCD and close to the zero recoil point.The separate heavy quark spin symmetries make it possible to describe all these decays using a single form factor.We also show how these constraints can be used to test the validity of different quark model calculations.bb to bc baryon decays are also discussed.     

Determination of J/ψ Event Number via J/ψ → μ^＋μ^- and J/ψ → e^＋e^- at BESⅢ

The decays of J/ψ → μ^＋μ^- and J/ψ → e^＋e^- are studied by Monte-Carlo simulation, based on the Beijing Spectrometer （BES）Ⅲ offtine software system. The methods of determination of the J/ψ event number via J/ψ → μ^＋μ^- and J/ψ → e^＋e^- are presented, respectively. These methods can be used to determine the J/ψ event number for the coming BESⅢ J/ψ data sample.     

Borexino实验探测到地球中微子

在意大利Gran Sasso国家实验室工作的物理学家,探测到地壳和地幔中的放射性衰变产生的电子反中微子.这一结果为新的直接测量地球深部发生的过程铺平了道路.