We search for the semi-inclusive process B_s^0 --> D_s^(*)D_s^(*) using 2.8 fb^-1 of ppbar collisions at s^(1/2) = 1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We observe 26.6 +/- 8.4 signal events with a significance above background of 3.2 standard deviations yielding a branching ratio of Br(B_s^0 --> D_s^(*)D_s^(*)) = 0.035 +/- 0.010(stat) +/- 0.011(syst). Under certain theoretical assumptions, these double-charm final states saturate CP-even eigenstates in the B_s^0 decays resulting in a width difference of Delta_Gamma_s^CP/Gamma_s = 0.072 +/- 0.021(stat) +/- 0.022(syst).
本文讨论了φ辐射衰变和γ(Ks->pi+pi-(gamma))/γ(Ks-> pi ~(0))比值的KLOE测量。第一个测量的目的是了解标量介子a0和f0的真实性质,它们可能的组成是qq,qqqq或KK分子。第二测量与相移差Δ 0-Δ 2的估计有关。由于辐射效应的存在,以前的测量受到很大的不确定性的影响,这些不确定性正确地包括在我们的分析中。
Measurement of the CP-violating weak phase phi[s] and the decay width difference Delta Gamma[s] using the Bs to J/Psi phi(1020) decay channel in pp collisions at sqrt(s) = 8 TeV
A model for the Delta(1600) resonance and gamma N -> Delta(1600) transition
用协变旁观者组分夸克模型研究了γ N → Delta(1600)跃迁。在跃迁过程中有两个重要的过程:一个光子耦合到Delta(1600)核的单个夸克(夸克核),一个光子耦合到中间的π介子-重子态(π介子云)。假设Delta(1600)是Delta(1232)的第一个径向激发,估算夸克核的贡献,而估算π介子云的贡献是基于与γ N -> Delta(1232)跃迁的类比。为了估计π云在γ N -> Delta(1600)跃迁中的贡献,我们包括了相关的中间态,π-N,π-Delta,π-N(1440)和π-Delta(1600)。预测了磁偶极跃迁形状因子GM*(Q2)以及螺旋度振幅A_1/2(Q2)和A_3/2(Q2)对四动量转移平方Q2的依赖性。将Q2=0时的结果与现有数据进行比较。
Radiative pi0 photoproduction on protons in the Delta+(1232) region
在MAMI-B电子加速器上,利用能量标记光子束,用Crystal Ball / TAPS探测器测量了反应γ p -> p π 0 γ '。在Delta+(1232)共振的能量范围内,用高统计量确定了发射光子γ '的能量和角微分截面以及π 0的角微分截面。将横截面和横截面与非辐射过程γ p -> p π 0的比率与具有反常磁矩kappa_Delta+作为自由参数的理论反应模型进行比较。由于模型计算无法详细再现实验分布的形状,因此目前无法提取kappa_Delta+。
Minimal Flavour Violation Waiting for Precise Measurements of Delta M_s, S_{psi phi}, A^s_SL, |V_ub|, gamma and B^0_{s,d} -> mu+ mu-
我们强调,CDF和D 0合作最近对B^0_s -棒B^0_s质量差Δ M_s的测量提供了一个重要的模型独立的最小味违反(MFV)检验。改进了么正三角角γ和树级衰变|V_ub|的测量,并结合将来对Delta M_s,S_{psi K_S},S_{psi phi},Br的精确测量,对它们的测量结果进行了讨论(B_{d,s} -> mu+ mu-),Br(B -> X_{d,s} nu bar nu),Br(K+ -> pi+ nu bar nu)和Br(K_L -> pi^0 nu bar nu)以及相关非微扰参数的改进值将允许以模型独立的方式以高精度检验MFV假设。特别地,从树级过程获得的参考么正三角形与MFV模型中的泛么正三角形(UUT)之间的差异将表示新的味道违反相互作用和/或新的局部算子,这些算子在具有低tan(beta)的MFV模型中被抑制,其中前者通过S_{psi phi}和K_L -> pi^0 nu bar nu进行最佳测试。还简要讨论了非MFV方案。在这种情况下,我们在最近的文献中确定了标准模型和新物理对S_{psi phi}的贡献之间的相对符号误差,这对S_{psi phi}和A^s_SL之间的相关性有影响。我们指出,比率S_{psi phi} /A^s_SL和(Delta M_s)/(Delta Gamma_s)将允许确定(Delta M_s)/(Delta M_…
Lowest Q^2 Measurement of the gamma*p -> Delta Reaction: Probing the Pionic Contribution
To determine nonspherical angular momentum amplitudes in hadrons at long ranges (low Q^2), data were taken for the p( \vec{e} ,e'p)π^0 reaction in the Delta region at Q^2=0.060 (GeV/c)^2 utilizing the magnetic spectrometers of the A1 Collaboration at MAMI. The results for the dominant transition magnetic dipole amplitude and the quadrupole to dipole ratios at W=1232 MeV are: M_{1+} ^{3/2} = (40.33 +/- 0.63_{stat+syst} +/- 0.61_{model}) (10^{-3}/ m_{π^+} ),Re( E_{1+} ^{3/2}/ M_{1+} ^{3/2}) = (-2.28 +/- 0.29_{stat+syst} +/- 0.20_{model})%, and Re( S_{1+} ^{3/2}/ M_{1+} ^{3/2}) = (-4.81 +/- 0.27_…