Non-zero transversity distribution of the pion in a quark-spectator-antiquark model

We calculate the non-zero (na\"{i}ve) T-odd transverse momentum dependent transversity distribution h_1^{\perp}(x,\kp^2) of the pion in a quark-spectator-antiquark model. The final-state interaction is modelled by the approximation of one gluon exchange between the quark and the antiquark spectator. Using our model result we estimate the unsuppressed cos2$\phi$ azimuthal asymmetry in unpolarized $\pi^-p$ Drell-Yan process. We find that the transverse momentum dependence of h_1^{\perp}(x,\kp^2) of the pion is the same as that of h_1^{\perp}(x,\kp^2) of the proton calculated from the quark-scalar-diquark model, although the $x$ dependencies of them are different from each other. This suggests a connection between cos2$\phi$ asymmetries in Drell-Yan processes with different initial hadrons.Comment: 6 LaTex Pages in Revtex format, 5 figures. Version to appear in PR

Sivers function in light-cone quark model and azimuthal spin asymmetries in pion electroproduction

We perform a calculation of Sivers function in a light-cone SU(6) quark-diquark model with both scalar diquark and vector diquark spectators. We derive the transverse momentum dependent light-cone wave function of the proton by taking into account the Melosh-Wigner rotation. By adopting one-gluon exchange, we obtain a non-vanishing Sivers function of $down$ quark from interference of proton spin amplitudes. We analyze the $\frac{|P_{h\perp}|}{M}$ weighted Sivers asymmetries in $\pi^+$, $\pi^-$ and $\pi^0$ electroproduction off transverse polarized proton target, averaged and not averaged by the kinematics of HERMES experiment.Comment: 17 LaTex pages, 2 figures. Final version for journal publicatio

Present status of treatment of chronic pain

Pain is a distressing experience associated with actual or potential tissue damage with sensory, emotional, cognitive and social components. Chronic pain is a common disease which can be divided into nociceptive pain, neuropathic pain and mixed pain according to pathophysiological mechanism. The treatment of chronic pain, at present, mainly includes minimally invasive interventional surgery and non-surgical treatment. Because pain medicine is a multi-disciplinary intersection of disciplines, the treatments of chronic pain remain multi-model ways. According to the pathogenesis of pain classification, different treatments of pain should be selected in targeted treatment program. This paper summarizes present status of chronic pain treatment. DOI: 10.3969/j.issn.1672-6731.2018.10.00