Thu·Jan 14, 2016Thursday·January 14, 2016

1. 01*

   Direct photon production and jet energy-loss in small systems

   Chun Shen🇨🇦 · Chanwook Park🇨🇦 · Jean-François Paquet🇨🇦 · Gabriel S. Denicol🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦

   Two types of penetrating probes, direct photon and QCD jets, are investigated in the background of a small and rapidly expanding droplet of quark-gluon plasma. The additional thermal electromagnetic radiation results in a $\sim$50\% enhancement of the direct photons. In high multiplicity p+Pb collisions, jets can lose a sizeable fraction of their initial energy, leading to a charged hadron $R_{\mathrm{pA}}$ of $\sim$0.8 at a transverse momentum around 10\,GeV. Those two proposed measurements can help understand the apparent collective behaviour observed in small collision systems.

   ↳ hep-phnucl-exnucl-thNPA(2016)·16 citations
2. 02*

   A systematic approach to sketch Bethe-Salpeter equation

   Si-xue Qin🇺🇸

   To study meson properties, one needs to solve the gap equation for the quark propagator and the Bethe-Salpeter (BS) equation for the meson wavefunction, self-consistently. The gluon propagator, the quark-gluon vertex, and the quark--anti-quark scattering kernel are key pieces to solve those equations. Predicted by lattice-QCD and Dyson-Schwinger analyses of QCD's gauge sector, gluons are non-perturbatively massive. In the matter sector, the modeled gluon propagator which can produce a veracious description of meson properties needs to possess a mass scale, accordingly. Solving the well-known longitudinal Ward-Green-Takahashi identities (WGTIs) and the less-known transverse counterparts together, one obtains a nontrivial solution which can shed light on the structure of the quark-gluon vertex. It is highlighted that the phenomenologically proposed anomalous chromomagnetic moment (ACM) vertex originates from the QCD Lagrangian symmetries and its strength is proportional to the magnitude of dynamical chiral symmetry breaking (DCSB). The color-singlet vector and axial-vector WGTIs can relate the BS kernel and the dressed quark-gluon vertex to each other. Using the relation, one can truncate the gap equation and the BS equation, systematically, without violating crucial symmetries, e.g., gauge symmetry and chiral symmetry.

   ↳ nucl-thhep-lathep-phnucl-exEPJ Web Conf.(2016)·11 citations
3. 03*

   Imaging the He${}_2$ quantum halo state using a free electron laser

   S. Zeller🇺🇸 · M. Kunitski · J. Voigtsberger · A. Kalinin · A. Schottelius · C. Schober · M. Waitz · H. Sann · A. Hartung · T. Bauer🇩🇪 · M. Pitzer · F. Trinter and 15 other authors

   We report on coulomb explosion imaging of the wavefunction of the quantum halo system He${}_2$. Each atom of this system is ionized by tunnelionization in a femto second laser pulse and in a second experiment by single photon ionization employing a free electron laser. We visualize the exponential decay of the probability density of the tunneling particle over distance for over two orders of magnitude up to an internuclear distance of 250 Å. By fitting the slope of the density in the tunneling regime we obtain a binding energy of 151.9 $\pm$ 13.3 neV, which is in agreement with most recent calculations.

   ↳ physics.atom-phnucl-exphysics.atm-clusphysics.chem-phProc.Nat.Acad.Sci.(2016)·18 citations
4. 04*

   A gas cell for stopping, storing and polarizing radioactive particles

   A. Sytema🇳🇱 · J.E. van den Berg🇳🇱 · O. Böll🇳🇱 · D. Chernowitz · E.A. Dijck🇳🇱 · J.O. Grasdijk · S. Hoekstra🇳🇱 · K. Jungmann🇳🇱 · S.C. Mathavan · C. Meinema🇳🇱 · A. Mohanty🇮🇳 · S.E. Müller🇳🇱 and 5 other authors

   A radioactive beam of 20Na is stopped in a gas cell filled with Ne gas. The stopped particles are polarized by optical pumping. The degree of polarization that can be achieved is studied. A maximum polarization of 50% was found. The dynamic processes in the cell are described with a phenomenological model.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2016)·2 citations
5. 05*

   Populating Low-Spin States in Radioactive Nuclei to Measure Magnetic Moments Using the Transient Field Technique

   D.A. Torres · F. Ramírez🇨🇴

   The experimental study of magnetic moments for nuclear states near the ground state, $I\ge 2$, provides a powerful tool to test nuclear structure models. The study of magnetic moments in nuclei far away from the stability line is the next frontier in such studies. Two techniques have been utilized to populated low-spin states in radioactive nuclei: coulomb excitation reactions using radioactive nuclei, and the transfer of $\alpha$ particles to stable beams to populate low spin states in radioactive nuclei. A presentations of these two techniques, along with the experimental challenges presented for future uses with nuclei far away from the stability line, will be presented.

   ↳ physics.ins-detnucl-exActa Phys.Polon.B(2016)·0 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.