Search

We report high-precision measurements of the deeply virtual Compton scattering (DVCS) cross section at high values of the Bjorken variable x_{B}. DVCS is sensitive to the generalized parton distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton form factors (CFFs) of the nucleon as a function of x_{B}, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs.

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q^{2}) up to 15.75 (GeV/c)^{2}. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q^{2} and double the range over which a longitudinal or transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q^{2} and attributed to hard two-photon exchange (TPE) effects, extending to 8 (GeV/c)^{2} the range of Q^{2} for which a discrepancy is established at >95% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q^{2}.

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of x_{B} (0.36, 0.48, and 0.60) and Q^{2} (3.1 to 8.4 GeV^{2}) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions dσ_{T}/dt+εdσ_{L}/dt, dσ_{TT}/dt, dσ_{LT}/dt, and dσ_{LT^{'}}/dt are extracted as a function of the proton momentum transfer t-t_{min}. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross section throughout this kinematic range. The data are well described by calculations based on transversity generalized parton distributions coupled to a helicity flip distribution amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

Positron beams, both polarized and unpolarized, are identified as important ingredients for the experimental programs at the next generation of lepton accelerators. In the context of the hadronic physics program at Jefferson Lab (JLab), positron beams are complementary, even essential, tools for a precise understanding of the electromagnetic structure of nucleons and nuclei, in both the elastic and deep-inelastic regimes. For instance, elastic scattering of polarized and unpolarized electrons and positrons from the nucleon enables a model independent determination of its electromagnetic form factors. Also, the deeply-virtual scattering of polarized and unpolarized electrons and positrons allows unambiguous separation of the different contributions to the cross section of the lepto-production of photons and of lepton-pairs, enabling an accurate determination of the nucleons and nuclei generalized parton distributions, and providing an access to the gravitational form factors of the energy-momentum tensor. Furthermore, positron beams offer the possibility of alternative tests of the Standard Model of particle physics through the search of a dark photon, the precise measurement of electroweak couplings, and the investigation of charged lepton flavor violation. This document discusses the perspectives of an experimental program with high duty-cycle positron beams at JLab.

Background: Many clinicians and researchers believe that “craving” an abusable substance is a central phenomenon related to addiction. Craving for alcohol appears to be intimately related to the loss of control over consumption and to compulsive alcohol use. Aim: To compare the scores of obsessive compulsive drinking scale with visual analogue scale, severity of alcohol dependence questionnaire and addiction severity index. Materials and Methods: Literate patients who met DCR-ICD-10 criteria for alcohol dependence syndrome were taken in the study and they must have been drinking alcohol daily till 1 week ago and the subjects were required to consume at least 6 standard drinks per day over the last month. Instruments used in this study were Obsessive Compulsive Drinking Scale– OCDS, Severity of Alcohol Dependence Questionnaire– SADQ, Addiction Severity Index– ASI, Visual Analogue Scale– VAS, Mini Mental Status Examination– MMSE, Timeline Method– TL Results: Among 40 patients, the mean age of these patients was 38 yrs (38.55 ± 9.60). 95% of them were Hindus and 5% christians. 82.5% were married. And 50% of patients has the income between Rs.15000-20000 per month. The correlation matrix of OCDS variables (OCDS-T,OCDS-O,OCDS-C),ASI-A,SADQ,VAS variables (G,F,I) and TL on all four follow-ups were measured. All correlations were positive and significant at p

Play behaviours are exhibited by many mammalian species. The similarity of such behaviour across children, non-human primates and rats makes it an especially appropriate target for the investigation of drug- or toxicant-induced disruption. In this study the acute effects of cocaine on play behaviour in male and female Sprague-Dawley rats was assessed. Same-sex dyads of rats (postnatal day 35-36) were separated 24 h prior to testing. On the following day, one or both rats of the dyad were injected with the same dose of cocaine (0, 2.5, 5.0 or 20.00 mg/kg). Thirty minutes later the rats were placed together and, after 5 min of habituation, the frequency of pins and crawl-overs were measured for each subject. In dyads in which both rats were treated, crawl-overs and pinning behaviour were decreased by 20 mg/kg cocaine. In dyads in which only one rat was treated, there was marginal effect of cocaine treatment on pinning frequency, while crawl-overs were unaffected. Pinning frequency was not sexually dimorphic in either type of dyad; however, crawl-overs were more frequently exhibited by females in dyads in which only one rat was treated. Thus, pinning behaviour in juvenile rats appears somewhat more sensitive to cocaine-induced disruption than crawl-over behaviours. Additionally, the presence of an untreated rat appears to attenuate the play-disrupting effects of cocaine on pinning frequency.