Form factors in B→ππℓνˉℓB\to \pi\pi\ell\bar\nu_\ell from QCD light-cone sum rules

The form factors of the semileptonic $B\to \pi\pi\ell\bar\nu$ decay are calculated from QCD light-cone sum rules with the distribution amplitudes of dipion states. This method is valid in the kinematical region, where the hadronic dipion state has a small invariant mass and simultaneously a large recoil. The derivation of the sum rules is complicated by the presence of an additional variable related to the angle between the two pions. In particular, we realize that not all invariant amplitudes in the underlying correlation function can be used, some of them generating kinematical singularities in the dispersion relation. The two sum rules that are free from these ambiguities are obtained in the leading twist-2 approximation, predicting the $\bar{B}^0\to \pi^+\pi^0$ form factors $F_{\perp}$ and $F_{\parallel}$ of the vector and axial $b\to u$ current, respectively. We calculate these form factors at the momentum transfers $0<q^2\lesssim 12$ GeV$^2$ and at the dipion mass close to the threshold $4m_\pi^2$. The sum rule results indicate that the contributions of the higher partial waves to the form factors are suppressed with respect to the lowest $P$-wave contribution and that the latter is not completely saturated by the $\rho$-meson term.Comment: 17 pages, 4 figures, a few comments and references added, version to be published in Nucl.Phys.

Heavy flavour energy loss from AdS/CFT: A novel diffusion coefficient

Two AdS/CFT based energy loss models are used to compute the suppression and azimuthal correlations of heavy quarks in heavy ion collisions. The model with a velocity independent diffusion coefficient is in good agreement with B and D meson data up to high $p_T$. The partonic azimuthal correlations we calculate exhibit an order of magnitude difference in low momentum correlations to pQCD calculations [arXiv:1305.3823]. We thus propose heavy flavour momentum correlations as a distinguishing observable of weakly- and strongly-coupled energy loss mechanisms.Comment: 4 pages, 2 figures. Proceedings for Strangeness in Quark Matter 2017. arXiv admin note: text overlap with arXiv:1703.0584

Extracting B→K∗B \to K^* Form Factors from Data

We extract ratios of $B \to K^*$ form factors at low hadronic recoil from recent data on $B \to K^* \mu^+ \mu^-$ decays in a model-independent way. The presented method will improve in the future with further (angular) studies in semileptonic rare B-decays and advance our understanding of form factors, which are important inputs in precision tests of the Standard Model

Perceptions of mental health care users diagnosed with major depressive disorder of factors that lead to readmission

A dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Occupational Therapy Johannesburg, 2017.Major Depressive Disorder tends to have a chronic course and Mental Health Care Users with this diagnosis experience challenges after discharge that impact recovery. A qualitative approach and descriptive design were used to explore these challenges and the perceived value that mental health care users attach to support group attendance after discharge. Data were gathered through semi-structured interviews with eleven participants. The transcribed interviews were analysed thematically. Data analysis generated four themes: “Inability to fully benefit from hospitalisation”, “Life was not what I expected it to be after discharge”, “I did not feel supported after discharge” and “Support groups could be valuable”. This study showed that learning is compromised during the acute phase of the disorder affecting the implementation of coping skills after discharge, that recovery is a journey that extends beyond hospitalisation, that the experience of isolation after discharge is detrimental to recovery and that support groups could compensate for some unmet treatment needs at discharge. Keywords: Major Depressive Disorder, challenges, readmission, occupational therapyLG201