Fri·Jul 8, 2011Friday·July 8, 2011

1. 01*

   Understanding the J/psi Production Mechanism at PHENIX

   Todd Kempel🇺🇸

   The large mass of the charm quark, along with the abundance of J/psi mesons observed from proton-proton collisions at PHENIX, allow for new measurements which are sensitive to basic properties of QCD. Two measurements are presented in this document: a transverse single-spin asymmetry (SSA) of J/psi production and the angular distribution for decay leptons in various reference frames. The decay distribution is directly sensitive to the J/psi production mechanism, while the transverse SSA is also sensitive to the distribution of gluons in a transversely polarized proton. Taken together, the two measurements provide a wealth of information about the formation of a J/psi meson.

   nucl-ex0 citations
2. 02*

   Comment on "Nuclear structure corrections in muonic deuterium"

   Gerald A. Miller🇺🇸

   A recent letter [1] investigated the effects of deuteron polarizability in the mu D atom. The importance of understanding this atom has been heightened because of the possible light it could shed on the proton radius puzzle. Here we confirm, clarify, and emphasize the significance of the result [1] that the effects of the third Zemach moment are canceled by part of the deuteron polarizability effects. 1. K. Pachucki, Phys. Rev. Lett. 106, 193007 (2011)

   ↳ physics.atom-phhep-phnucl-exnucl-th0 citations
3. 03*

   Dynamical effects in proton breakup from exotic nuclei

   Ravinder Kumar (a, b)🇮🇹 · Angela Bonaccorso (a) · ((a) INFN, Sez. di Pisa and (b) Dipartimento di Fisica, Università di Pisa, Italy)

   We study dynamical effects in proton breakup from a weakly bound state in an exotic nucleus on a heavy target. The Coulomb interactions between the proton and the core and the proton and the target are treated to all orders, including also the full multipole expansion of the Coulomb potential. The dynamics of proton nuclear and Coulomb breakup is compared to that of an equiva- lent neutron of larger binding energy in order to elucidate the differences with the well understood neutron breakup mechanism. A number of experimentally measurable observables such as parallel momentum distributions, proton angular distributions and total breakup cross sections are calculated. With respect to nuclear breakup it is found that a proton behaves exactly as a neutron of larger binding energy. The extra 'effective energy' is due to the combined core-target Coulomb barrier. In Coulomb breakup we distinguish the effect of the core-target Coulomb potential (called recoil effect), with respect to which the proton behaves again as a more bound neutron, from the direct proton-target Coulomb potential. The latter gives cross sections about an order of magnitude larger than the recoil term. The two effects give rise to complicated interferences in the parallel momentum distributions. They are instead easily separable in the proton angular distributions which are therefore suggested as a very useful observable for future experimental studies.

   ↳ nucl-thnucl-exPRC(2011)·42 citations
4. 04*

   Studying Exotic Hadrons in Heavy Ion Collisions

   ExHIC Collaboration : Sungtae Cho🇰🇷 · Takenori Furumoto🇯🇵 · Tetsuo Hyodo🇯🇵 · Daisuke Jido🇯🇵 · Che Ming Ko🇺🇸 · Su Houng Lee🇰🇷 · Marina Nielsen🇧🇷 · Akira Ohnishi🇯🇵 · Takayasu Sekihara🇯🇵 · Shigehiro Yasui🇯🇵 · Koichi Yazaki🇯🇵

   We investigate the possibilities of using measurements in present and future experiments on heavy ion collisions to answer some longstanding problems in hadronic physics, namely identifying hadronic molecular states and exotic hadrons with multiquark components. The yields of a selected set of exotic hadron candidates in relativistic heavy ion collisions are discussed in the coalescence model in comparison with the statistical model. We find that the yield of a hadron is typically an order of magnitude smaller when it is a compact multiquark state, compared to that of an excited hadronic state with normal quark numbers. We also find that some loosely bound hadronic molecules are formed more abundantly than the statistical model prediction by a factor of two or more. Moreover, due to the significant numbers of charm and bottom quarks produced at RHIC and even larger numbers expected at LHC, some of the proposed heavy exotic hadrons could be produced with sufficient abundance for detection, making it possible to study these new exotic hadrons in heavy ion collisions.

   ↳ nucl-thhep-phnucl-exPRC(2011)·163 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.