Mon·Feb 15, 2016Monday·February 15, 2016

1. 01*

   The RHIC Cold QCD Plan for 2017 to 2023: A Portal to the EIC

   Elke-Caroline Aschenauer (BNL)🇺🇸 · Christine Aidala (U. Michigan)🇺🇸 · Alexander Bazilevsky (BNL)🇺🇸 · Markus Diehl (DESY)🇩🇪 · Renee Fatemi (Kentucky U.)🇺🇸 · Carl Gagliardi (Texas A&M)🇺🇸 · Zhongbo Kang (Los Alamos)🇺🇸 · Yuri V. Kovchegov (Ohio State U.)🇺🇸 · Jamal Jalilian-Marian (Baruch U.)🇺🇸 · John Lajoie (Iowa State U.)🇺🇸 · Dennis V. Perepelitsa (BNL)🇺🇸 · Ralf Seidl (Riken)🇯🇵 and 7 other authors

   The exploration of the fundamental structure of strongly interacting matter has always thrived on the complementarity of lepton scattering and purely hadronic probes. As the community eagerly anticipates a future electron ion collider (EIC) in the U.S., an outstanding scientific opportunity remains to complete "must-do" measurements in p+p and p+A physics in the years preceding the EIC. As we describe in this document, these measurements will be essential to fully realize the scientific promise of the EIC by provid-ing a comprehensive set of measurements in hadronic collisions that, when combined with data from the EIC, will establish the validity and limits of factorization and universality. The outlined program will on the one hand lay the groundwork for the EIC, both scientifically and in terms of refining the experimental requirements for the physics program at the EIC, and thus be the natural next step on the path towards an electron-ion collider. On the other hand, while much of the physics in this program is unique to proton-proton and proton-nucleus collisions and offers discovery potential on its own, when combined with data from the EIC it will provide a broad foundation to a deeper understanding of fundamental QCD.

   nucl-ex105 citations
2. 02*

   Search for Pentaquark Theta+ in Hadronic Reaction at J-PARC

   M. Naruki (for the J-PARC E19 Collaboration)🇯🇵

   A variety of nuclear and hadron physics experiments are being performed using meson beams at the J-PARC Hadron Facility. As the first experiment at the facility, the pentaquark Theta+ was searched for in the pi- p -> K- X reaction with a missing-mass resolution of 2 MeV (FWHM). The number of accumulated beam pions are 7.8x10^10 and 8.1x10^10 for different beam momenta of 1.92 and 2.01 GeV/c, respectively. No significant structure was observed in the missing mass spectra. Upper limits of the production cross section are obtained to be 0.28ub/sr in the laboratory frame at 90% confidence level for each beam momenta. With a help of theoretical models, an upper limit of the total decay width of Theta+ was estimated to be 0.36 and 1.9 MeV for J^P = 1/2+ and 1/2- states, respectively.

   nucl-exhep-phActa Phys.Polon.B(2016)·3 citations
3. 03*

   New cross section data and review of production routes of medically used ${}^{110m}$In

   F. Tárkányi · S. Takács🇭🇺 · F. Ditrói🇭🇺 · A. Hermanne🇧🇪 · M. Baba · B.M.A. Mohsena · A.V. Ignatyuk

   Evaluation of nuclear data for production routes of ${}^{110m}$In is in progress in the frame of an IAEA Coordinated Research Project (CRP). New experimental cross section data for the indirect ${}^{nat}$In(p,x)${}^{110}$Sn $⟶$ ${}^{110m}$In and for the direct ${}^{107}$Ag($\alpha$,n)${}^{110m}$In and ${}^{109}$Ag(${}^3$He,2n)${}^{110m}$In production routes and for the satellite impurity reactions ${}^{107}$Ag($\alpha$,xn)${}^{110g,109}$In and ${}^{109}$Ag(${}^3$He,xn)${}^{110g,111,109}$In have been measured by using the activation method, stacked foil irradiation technique and gamma-ray spectrometry. Additional data are reported for production of the ${}^{111}$In diagnostic gamma-emitter via the ${}^{109}$Ag($\alpha$,2n)${}^{111}$In reaction. The earlier experimental data were critically reviewed in order to prepare recommended data and optimal production parameters for the different routes.

   nucl-exNucl.Instrum.Meth.B(2015)·9 citations
4. 04*

   Study of collective flows of protons and ${\pi }^{-}$ -mesons in p(C, Ta) and He(Li, C) collisions at momenta of 4.2, 4.5 and 10 AGeV/c

   L. Chkhaidze🇬🇪 · G. Chlachidze🇺🇸 · T. Djobava🇬🇪 · A. Galoyan🇷🇺 · L. Kharkhelauri🇬🇪 · R. Togoo🇲🇳 · V. Uzhinsky🇷🇺

   Collective flows of protons and ${\pi }^{-}$-mesons are studied at the momenta of 4.2, 4.5 and 10 AGeV/c for p(C, Ta) and He(Li, C) interactions. The data were obtained from the streamer chamber (SKM-200-GIBS) and from the Propane Bubble Chamber (PBC-500) systems utilized at JINR. The method of Danielewicz and Odyniec has been employed in determining the directed transverse flow of particles. The values of the transverse flow parameter and the strength of the anisotropic emission were defined for each interacting nuclear pair. It is found that the directed flows of protons and pions decrease with increase of the energy and the mass numbers of colliding nucleus pairs. The ${\pi }^{-}$-meson and proton flows exhibit opposite directions in all studied interactions, and the flows of protons are directed in the reaction plane. The Ultra-relativistic Quantum Molecular Dynamical Model (UrQMD), enlarged by the Statistical Multi-fragmentation Model (SMM), satisfactorily describes obtained experimental results.

   nucl-exhep-exEPJA(2016)·1 citation
5. 05*

   INFN What Next: Ultra-relativistic Heavy-Ion Collisions

   A. Dainese🇮🇹 · E. Scomparin🇮🇹 · G. Usai🇮🇹 · P. Antonioli🇮🇹 · R. Arnaldi🇮🇹 · A. Beraudo🇮🇹 · E. Bruna🇮🇹 · G.E. Bruno🇮🇹 · S. Bufalino🇮🇹 · P. Di Nezza🇮🇹 · M.P. Lombardo🇮🇹 · R. Nania🇮🇹 and 129 other authors

   This document was prepared by the community that is active in Italy, within INFN (Istituto Nazionale di Fisica Nucleare), in the field of ultra-relativistic heavy-ion collisions. The experimental study of the phase diagram of strongly-interacting matter and of the Quark-Gluon Plasma (QGP) deconfined state will proceed, in the next 10-15 years, along two directions: the high-energy regime at RHIC and at the LHC, and the low-energy regime at FAIR, NICA, SPS and RHIC. The Italian community is strongly involved in the present and future programme of the ALICE experiment, the upgrade of which will open, in the 2020s, a new phase of high-precision characterisation of the QGP properties at the LHC. As a complement of this main activity, there is a growing interest in a possible future experiment at the SPS, which would target the search for the onset of deconfinement using dimuon measurements. On a longer timescale, the community looks with interest at the ongoing studies and discussions on a possible fixed-target programme using the LHC ion beams and on the Future Circular Collider.

   nucl-exnucl-thFrascati Phys.Ser.(2016)·9 citations
6. 06*

   Improved empirical parametrizations of the ${\gamma }^{\ast }N\to \Delta (1232)$ and ${\gamma }^{\ast }N\to N(1520)$ helicity amplitudes and the Siegert's theorem

   G. Ramalho🇧🇷

   In the nucleon electroexcitation reactions, ${\gamma }^{\ast }N\to R$, where $R$ is a nucleon resonance ($N^{\ast }$), the electric amplitude $E$, and the longitudinal amplitude $S_{1/2}$, are related by $E\propto \frac{\omega }{|\mathbf{q}|}{S}_{1/2}$, at the pseudo-threshold limit ($|\mathbf{q}|\to 0$), where $\omega$ and $|\mathbf{q}|$ are respectively the energy and the magnitude of three-momentum of the photon. The previous relation is usually refereed as the Siegert's theorem. The form of the electric amplitude, defined in terms of the transverse amplitudes $A_{1/2}$ and $A_{3/2}$, and the explicit coefficients of the relation, depend on the angular momentum and parity ($J^P$) of the resonance $R$. The Siegert's theorem is the consequence of the structure of the electromagnetic transition current, which induces constraints between the electromagnetic form factors in the pseudo-threshold limit. In the present work, we study the implications of the Siegert's theorem for the ${\gamma }^{\ast }N\to \Delta (1232)$ and ${\gamma }^{\ast }N\to N(1520)$ transitions. For the ${\gamma }^{\ast }N\to N(1520)$ transition, in addition to the relation between electric amplitude and longitudinal amplitude, we obtain also a relation between the two transverse amplitudes: $A_{1/2}=A_{3/2}/\sqrt{3}$, at the pseudo-threshold. % The constraints at the pseudo-threshold are tested for the MAID2007 parametrizations of the reactions under discussion. New parametrizations for the amplitudes $A_{1/2}$, $A_{3/2}$ and $S_{1/2}$, for the ${\gamma }^{\ast }N\to \Delta (1232)$ and ${\gamma }^{\ast }N\to N(1520)$ transitions, valid for small and large $Q^2$, are proposed. The new parametrizations are consistent with both: the pseudo-threshold constraints (Siegert's theorem) and the empirical data.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2016)·30 citations
7. 07*

   The pion: an enigma within the Standard Model

   Tanja Horn🇺🇸 · Craig D. Roberts🇺🇸

   Almost 50 years after the discovery of gluons & quarks, we are only just beginning to understand how QCD builds the basic bricks for nuclei: neutrons, protons, and the pions that bind them. QCD is characterised by two emergent phenomena: confinement & dynamical chiral symmetry breaking (DCSB). They are expressed with great force in the character of the pion. In turn, pion properties suggest that confinement & DCSB are closely connected. As both a Nambu-Goldstone boson and a quark-antiquark bound-state, the pion is unique in Nature. Developing an understanding of its properties is thus critical to revealing basic features of the Standard Model. We describe experimental progress in this direction, made using electromagnetic probes, highlighting both improvements in the precision of charged-pion form factor data, achieved in the past decade, and new results on the neutral-pion transition form factor. Both challenge existing notions of pion structure. We also provide a theoretical context for these empirical advances, first explaining how DCSB works to guarantee that the pion is unnaturally light; but also, nevertheless, ensures the pion is key to revealing the mechanisms that generate nearly all the mass of hadrons. Our discussion unifies the charged-pion elastic and neutral-pion transition form factors, and the pion's twist-2 parton distribution amplitude. It also indicates how studies of the charged-kaon form factor can provide significant contributions. Importantly, recent predictions for the large-$Q^2$ behaviour of the pion form factor can be tested by experiments planned at JLab 12. Those experiments will extend precise charged-pion form factor data to momenta that can potentially serve in validating factorisation theorems in QCD, exposing the transition between the nonperturbative and perturbative domains, and thereby reaching a goal that has long driven hadro-particle physics.

   ↳ nucl-thhep-exhep-lathep-ph+1J.Phys.G(2016)·192 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.