Mon·Sep 5, 2016Monday·September 5, 2016

1. 01*

   The role of $a_1(1260)$ in ${\pi }^{-}p\to a_1^{-}(1260)p$ and ${\pi }^{-}p\to {\pi }^{-}{\rho }^{0}p$ reactions near threshold

   Chen Cheng🇨🇳 · Ju-Jun Xie🇨🇳 · Xu Cao🇨🇳

   We report on a theoretical study of the ${\pi }^{-}p\to a_1^{-}(1260)p$ and ${\pi }^{-}p\to {\pi }^{-}{\rho }^{0}p$ reactions near threshold within an effective Lagrangian approach. The production process is described by $t$-channel ${\rho }^0$ meson exchange. For the ${\pi }^{-}p\to {\pi }^{-}{\rho }^{0}p$ reaction, the final ${\pi }^{-}{\rho }^0$ results from the decay of the $a_1(1260)$ resonance which is assumed as a dynamically generated state from the $K^{\ast }\bar{K}$ and $\rho \pi$ coupled channel interactions. We calculate the total cross section of the ${\pi }^{-}p\to a_1^{-}(1260)p$ reaction. It is shown that, with the coupling constant of the $a_1(1260)$ to $\rho \pi$ channel obtained from the chiral unitary theory and a cut off parameter ${\Lambda }_{\rho }\sim 1.5$ GeV in the form factors, the experimental measurement can be reproduced. Furthermore, the total and differential cross sections of ${\pi }^{-}p\to a_1^{-}(1260)p\to {\pi }^{-}{\rho }^{0}p$ reaction are evaluated, and it is expected that our model calculations can be tested by future experiments. These reactions are important for the study of the $a_1(1260)$ resonance and would provide further clue for the nature of $a_1(1260)$ state.

   ↳ nucl-thhep-phnucl-exCommun.Theor.Phys.(2016)·10 citations
2. 02*

   Evidence for a dynamically refracted primary bow in weakly bound ${}^9$Be rainbow scattering from ${}^{16}$O

   S. Ohkubo🇯🇵 · Y. Hirabayashi🇯🇵

   We present for the first time evidence for the existence of a dynamically refracted primary bow for ${}^9$Be+${}^{16}$O scattering. This is demonstrated through the use of coupled channel calculations with an extended double folding potential derived from the density-dependent effective two-body force and precise microscopic cluster wave functions for ${}^9$Be. The calculations reproduce the experimental Airy structure in ${}^9$Be+${}^{16}$O scattering well.It is found that coupling of a weakly bound ${}^9$Be nucleus to excited states plays the role of a booster lens, dynamically enhancing the refraction over the {\it static} refraction due to the Luneburg lens mean field potential between the ground states of ${}^9$Be and ${}^{16}$O.

   ↳ nucl-thnucl-exPRC(2016)·4 citations
3. 03*

   A Search for the LHCb Charmed 'Pentaquark' using Photo-Production of $J/\psi$ at Threshold in Hall C at Jefferson Lab

   Z.-E. Meziani🇺🇸 · S. Joosten🇺🇸 · M. Paolone🇺🇸 · E. Chudakov🇺🇸 · M. Jones🇺🇸 · K. Adhikari🇺🇸 · K. Aniol🇺🇸 · W. Armstrong🇺🇸 · J. Arrington🇺🇸 · A. Asaturyan🇦🇲 · H. Atac🇺🇸 · S. Bae🇰🇷 and 47 other authors

   We propose to measure the photo-production cross section of $J/\psi$ near threshold, in search of the recently observed LHCb hidden-charm resonances $P_c$(4380) and $P_c$(4450) consistent with 'pentaquarks'. The observation of these resonances in photo-production will provide strong evidence of the true resonance nature of the LHCb states, distinguishing them from kinematic enhancements. A bremsstrahlung photon beam produced with an 11 GeV electron beam at CEBAF covers the energy range of $J/\psi$ production from the threshold photo-production energy of 8.2 GeV, to an energy beyond the presumed $P_c$(4450) resonance. The experiment will be carried out in Hall C at Jefferson Lab using a 50{\mu}A electron beam incident on a 9% copper radiator. The resulting photon beam passes through a 15 cm liquid hydrogen target, producing $J/\psi$ mesons through a diffractive process in the $t$-channel, or through a resonant process in the $s$- and $u$-channel. The decay $e^{+}{e}^{-}$ pair of the $J/\psi$ will be detected in coincidence using the two high-momentum spectrometers of Hall C. The spectrometer settings have been optimized to distinguish the resonant $s$- and $u$-channel production from the diffractive $t$-channel $J/\psi$ production. The $s$- and $u$-channel production of the charmed 5-quark resonance dominates the $t$-distribution at large $t$. The momentum and angular resolution of the spectrometers is sufficient to observe a clear resonance enhancement in the total cross section and $t$-distribution. We request a total of 11 days of beam time with 9 days to carry the main experiment and 2 days to acquire the needed $t$-channel elastic $J/\psi$ production data for a calibration measurement. This calibration measurement in itself will greatly enhance our knowledge of $t$-channel elastic $J/\psi$ production near threshold.

   ↳ hep-exnucl-ex56 citations
4. 04*

   Characterization of single layer anti-reflective coatings for bolometer-based rare event searches

   E. V. Hansen🇺🇸 · N. DePorzio🇺🇸 · L. Winslow🇺🇸

   Combining analysis from phonon signals and photon signals is a powerful technique for reducing backgrounds in bolometer-based rare event searches. Anti-reflective coatings can significantly increase the performance of the secondary light-sensing bolometer in these experiments. As a first step toward these improvements, coatings of SiO${}_2$, HfO${}_2$, and TiO${}_2$ on Ge and Si wafers were fabricated and characterized at room temperature and multiple angles of incidence.

   ↳ physics.ins-detnucl-exJINST(2017)·5 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.