Factorization of Radiative Leptonic Decays of B−B^- and D−D^- Mesons Including the Soft Photon Region

In this work, we study the radiative leptonic decays of $B^-$ and $D^-$ mesons using factorization approach. Factorization is proved to be valid explicitly at 1-loop level at any order of $O(\Lambda_{\rm QCD}\left/m_Q\right.)$. We consider the contribution in the soft photon region that $E_{\gamma} \sim \left. \Lambda^2_{\rm QCD} /\right. m_Q$. The numerical results shows that, the soft photon region is very important for both the $B$ and $D$ mesons. The branching ratios of $B\to \gamma e\nu_e$ is $5.21\times 10^{-6}$, which is about $3$ times of the result obtained by only considering the hard photon region $E_{\gamma}\sim m_Q$. And for the case of $D\to \gamma e\nu_e$, the result of the branching ratio is $1.92\times 10^{-5}$.Comment: arXiv admin note: text overlap with arXiv:1409.035

Factorization of Radiative Leptonic Decays of B−B^- and D−D^- Mesons

In this work, we study the factorization of the radiative leptonic decays of $B^-$ and $D^-$ mesons, the contributions of the order $O(\Lambda _{\rm QCD}\left/m_Q\right.)$ are taken into account. The factorization is proved to be valid explicitly at the order $O(\alpha _s\Lambda _{\rm QCD}\left/m_Q\right.)$. The hard kernel is obtained. The numerical results are calculated using the wave-function obtained in relativistic potential model. The $O(\Lambda _{\rm QCD}\left/m_Q\right.)$ contribution is found to be very important, the correction to the decay amplitudes of $B^-\to \gamma e\bar{\nu}$ is about $20\% - 30\%$. For $D$ mesons, the $O(\Lambda _{\rm QCD}\left/m_Q\right.)$ contributions are more important.Comment: 26 pages, 8 figures. Version to appear in Nucl. Phys.

Influence of post-traumatic stress disorder on pain experience in subjects on opioid maintenance therapy

Thesis (M.A.)--Boston UniversityPost-traumatic stress disorder (PTSD) and pain often co-occur in the same subjects. Chronic pain is a common symptom in subjects with PTSD and PTSD is a risk factor for chronic pain and the related disability. PTSD is also highly prevalent in subjects with substance abuse disorders. While a number of studies have examined interactions between PTSD and chronic pain in general populations, these studies have generally used self-reported pain instead of experimental pain testing methods. To date, little is known regarding the influence of PTSD on pain experience in subjects on opioid maintenance therapy for the treatment of opioid addiction. We tested the hypothesis that PTSD is associated with altered pain experience in subjects on opioid maintenance therapy. Specifically, we examined whether subjects with PTSD would 1) have altered sensitivity (pain tolerance and temporal pain summation) to experimental pain testing and 2) self-report higher pain severity and pain interference as compared to controls. Forty-one eligible subjects were assessed in the study. All subjects were screened for PTSD using the PTSD Checklist Civilian Version (PCL-C). A PCL-C score ≥ 44 was considered as a positive PTSD diagnosis. The experimental pain testing and self-assessment of pain experience were compared between subjects with and without PTSD. Multivariate analysis was used to assess the relation between PTSD and the pain responses adjusting the covariates. Our results showed that the presence of PTSD did not alter the response to experimental pain testing but significantly increased the degree of pain interference as revealed by the subjects’ self-assessment of pain experience. These divergent results suggest that in subjects with PTSD there is a disconnection between self-reported pain experience and response to experimental pain testing with an objective stimulus. The findings discussed in this thesis are limited by small sample size. Further study with a larger sample size and broader array of pain tests is suggested

The Role of Chaos in One-Dimensional Heat Conductivity

We investigate the heat conduction in a quasi 1-D gas model with various degree of chaos. Our calculations indicate that the heat conductivity $\kappa$ is independent of system size when the chaos of the channel is strong enough. The different diffusion behaviors for the cases of chaotic and non-chaotic channels are also studied. The numerical results of divergent exponent $\alpha$ of heat conduction and diffusion exponent $\beta$ are in consistent with the formula $\alpha=2-2/\beta$. We explore the temperature profiles numerically and analytically, which show that the temperature jump is primarily attributed to superdiffusion for both non-chaotic and chaotic cases, and for the latter case of superdiffusion the finite-size affects the value of $\beta$ remarkably.Comment: 6 pages, 7 figure

The design of a multi-channel spin polarimeter

All commercial electron spin polarimeters work in single channel mode, which is the bottleneck of researches by spin-resolved photoelectron spectroscopy. By adopting the time inversion antisymmetry of magnetic field, we developed a multichannel spin polarimeter based on normal incident VLEED. The key point to achieve the multi-channel measurements is the spatial resolution of the electron optics. The test of the electron optics shows that the designed spatial resolution can be achieved and an image type spin polarimeter with 100 times 100, totally ten thousand channels is possible to be realized.Comment: submitted to Chinese Physics

Delay-dependent robust stability of stochastic delay systems with Markovian switching

In recent years, stability of hybrid stochastic delay systems, one of the important issues in the study of stochastic systems, has received considerable attention. However, the existing results do not deal with the structure of the diffusion but estimate its upper bound, which induces conservatism. This paper studies delay-dependent robust stability of hybrid stochastic delay systems. A delay-dependent criterion for robust exponential stability of hybrid stochastic delay systems is presented in terms of linear matrix inequalities (LMIs), which exploits the structure of the diffusion. Numerical examples are given to verify the effectiveness and less conservativeness of the proposed method

Population dynamical behavior of Lotka-Volterra system under regime switching

In this paper, we investigate a Lotka-Volterra system under regime switching dx(t) = diag(x1(t); : : : ; xn(t))[(b(r(t)) + A(r(t))x(t))dt + (r(t))dB(t)]; where B(t) is a standard Brownian motion. The aim here is to find out what happens under regime switching. We first obtain the sufficient conditions for the existence of global positive solutions, stochastic permanence and extinction. We find out that both stochastic permanence and extinction have close relationships with the stationary probability distribution of the Markov chain. The limit of the average in time of the sample path of the solution is then estimated by two constants related to the stationary distribution and the coefficients. Finally, the main results are illustrated by several examples