Non-spectator Contributions To The Lifetime of Λb\Lambda_{b}

In this work, we evaluate the contributions of non-spectator effects to the lifetimes of $\Lambda_b$ and B-mesons. Based on the well-established models and within a reasonable range of the concerned parameters, the contributions can reduce the lifetime of $\Lambda_b$ by $7 \sim 8$ compared to that of B-mesons which are not significantly affected. This might partly explain the measured ratio $\tau(\Lambda_{b})/\tau(B^{0})=0.79$ \cite{Data}, which has been a long-standing discrepancy between theory and experimental data

Instantaneous Bethe-Salpeter Equation and Its Exact Solution

We present an approach to solve a Bethe-Salpeter (BS) equation exactly without any approximation if the kernel of the BS equation exactly is instantaneous, and take positronium as an example to illustrate the general features of the solutions. As a middle stage, a set of coupled and self-consistent integration equations for a few scalar functions can be equivalently derived from the BS equation always, which are solvable accurately. For positronium, precise corrections to those of the Schr\"odinger equation in order $v$ (relative velocity) in eigenfunctions, in order $v^2$ in eigenvalues, and the possible mixing, such as that between $S$ ($P$) and $D$ ($F$) components in $J^{PC}=1^{--}$ ($J^{PC}=2^{++}$) states as well, are determined quantitatively. Moreover, we also point out that there is a problematic step in the classical derivation which was proposed first by E.E. Salpeter. Finally, we emphasize that for the effective theories (such as NRQED and NRQCD etc) we should pay great attention on the corrections indicated by the exact solutions.Comment: 4 pages, replace for shortening the manuscrip

Incidence of central nervous system metastases in patients with human epidermal growth factor receptor 2-positive metastatic breast cancer treated with trastuzumab: A meta-analysis

This study aimed to estimate the incidence of central nervous system (CNS) metastases in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) treated with trastuzumab. Studies were identified through a literature search of electronic databases. Random-effects meta-analyses were performed to estimate the incidence rate of CNS metastases, trastuzumab therapy duration, and time from trastuzumab therapy to CNS metastasis diagnosis. A meta-analysis of odds ratios was performed to evaluate the significance of a difference in CNS metastasis incidence between patients with and without trastuzumab treatment. Thirty studies (8121 trastuzumab-treated and 3972 control patients) were included. The follow-up duration was 18.9 months (95% confidence interval [CI]: 13.8, 24.1). The trastuzumab treatment duration was 9.0 months (95% CI: 7.0, 11.0). The median interval between the start of trastuzumab therapy and CNS metastasis diagnosis was 12.2 months (95% CI: 9.5, 14.7). The incidence of CNS metastasis after the start of trastuzumab therapy was 22% (95% CI: 16, 27). The incidence of CNS metastases was significantly higher in trastuzumab-treated than in non-trastuzumab-treated patients (odds ratio: 1.39 [95% CI: 1.06, 1.82], p=0.02). The survival time from the start of the study was 23.4 months (95% CI: 19.7, 27.1) in trastuzumab-treated patients and 18.4 months (95% CI: 12.7, 24.1) in patients treated with control regimens. The survival time after the development of CNS metastases in trastuzumab-treated patients was 19.2 months (95% CI: 15.6, 25.9). Approximately 22% of patients with HER2-positive MBC who were treated with trastuzumab developed CNS metastases. However, trastuzumab-treated patients had a longer survival than patients who were not treated with trastuzumab

Two-loop gluino contributions to neutron electric dipole moment in CP violating MSSM

We analyze two-loop gluino corrections to the neutron electric dipole moment (EDM) in the minimal supersymmetry extension of the standard model (MSSM). The dependence of two-loop corrections on the relevant CP violating phases differs from that of the one-loop contributions, and there is a region in the parameter space where the two-loop contributions are comparable with the one-loop contributions. Our numerical results show that the two-loop corrections can be as large as 30% of the one-loop results.Comment: Revtex, 27 pages, including 11 ps figure

Does share pledging promote or impede corporate social responsibility? An examination of Chinese listed firms

By employing the Chinese listed firm’s data from 2010 to 2017, this study explores the impact of share pledging on firms’ corporate social responsibility (CSR) performance. Empirical results indicate a negative relationship between share pledging and CSR performance. This effect is robust after using alternative measures and different regression methods, and also consistent after tackling the endogenous issues. Furthermore, we find that risk-taking and agency cost are two possible underlying mechanisms through which share pledging reduces CSR. In addition, CSR reduction caused by share pledging leads to poorer economic performance and lower market value of firms