Thu·Jun 2, 2016Thursday·June 2, 2016

1. 01*

   Coulomb dissociation of ${}^{20,21}$N

   Marko Röder🇩🇪 · Tatsuya Adachi🇯🇵 · Yulia Aksyutina · Juan Alcantara · Sebastian Altstadt🇩🇪 · Hector Alvarez-Pol🇪🇸 · Nicholas Ashwood🇬🇧 · Leyla Atar🇩🇪 · Thomas Aumann🇩🇪 · Vladimir Avdeichikov🇸🇪 · M. Barr · Saul Beceiro🇺🇸 and 111 other authors

   Neutron-rich light nuclei and their reactions play an important role for the creation of chemical elements. Here, data from a Coulomb dissociation experiment on ${}^{20,21}$N are reported. Relativistic ${}^{20,21}$N ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the ${}^{19}\mathrm{N}(\mathrm{n},\gamma {)}^{20}\mathrm{N}$ and ${}^{20}\mathrm{N}(\mathrm{n},\gamma {)}^{21}\mathrm{N}$ excitation functions and thermonuclear reaction rates have been determined. The ${}^{19}\mathrm{N}(\mathrm{n},\gamma {)}^{20}\mathrm{N}$ rate is up to a factor of 5 higher at $T<1$\,GK with respect to previous theoretical calculations, leading to a 10\,\% decrease in the predicted fluorine abundance.

   nucl-exPRC(2016)·15 citations
2. 02*

   Elliptic flow of electrons from heavy-flavour hadron decays at mid-rapidity in Pb-Pb collisions at $\sqrt{{\mathbf{s}}_{\mathrm{NN}}}$ = 2.76 TeV

   ALICE Collaboration

   The elliptic flow of electrons from heavy-flavour hadron decays at mid-rapidity ($|y|$ $<$ 0.7) is measured in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV with ALICE at the LHC. The particle azimuthal distribution with respect to the reaction plane can be parametrized with a Fourier expansion, where the second coefficient ($v_2$) represents the elliptic flow. The $v_2$ coefficient of inclusive electrons is measured in three centrality classes (0-10%, 10-20% and 20-40%) with the event plane and the scalar product methods in the transverse momentum ($p_{\mathrm{T}}$) intervals 0.5-13 GeV/$c$ and 0.5-8 GeV/$c$, respectively. After subtracting the background, mainly from photon conversions and Dalitz decays of neutral mesons, a positive $v_2$ of electrons from heavy-flavour hadron decays is observed in all centrality classes, with a maximum significance of $5.9\sigma$ in the interval $2<$ $p_{\mathrm{T}}$ $<$ 2.5 GeV/$c$ in semi-central collisions (20-40%). The value of $v_2$ decreases towards more central collisions at low and intermediate $p_{\mathrm{T}}$ (0.5 $<$ $p_{\mathrm{T}}$ $<$ 3 GeV/$c$). The $v_2$ of electrons from heavy-flavour hadron decays at mid-rapidity is found to be similar to the one of muons from heavy-flavour hadron decays at forward rapidity (2.5 $<$ $y$ $<$ 4). The results are described within uncertainties by model calculations including substantial elastic interactions of heavy quarks with an expanding strongly-interacting medium.

   nucl-exhep-exJHEP(2016)·53 citations
3. 03*

   Quantum corrections to the Relativistic mean-field theory

   Sergei P. Maydanyuk (1 and 2)🇺🇦 · Peng-Ming Zhang (1)🇨🇳 · Ahmed Bakry (1) ((1) Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000, China, (2) Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kiev, 03680, Ukraine)🇨🇳

   In this paper, we compare the RMF theory and the model of deformed oscillator shells (DOS) in description of the quantum properties of the bound states of the spherically symmetric light nuclei. We obtain an explicit analytical relation between differential equations for the RMF theory and DOS model, which determine wave functions for nucleons. On such a basis we perform analysis of correspondence of quantum properties of nuclei. We find: (1) Potential $V_{RMF}$ of the RMF theory for nucleons has the wave functions $f$ and $g$ with joint part $h$ coincident exactly with the nucleon wave function of DOS model with potential $V_{\mathrm{shell}}$. But, a difference between $V_{RMF}$ and $V_{\mathrm{shell}}$ is essential for any nucleus. (2) The nucleon wave functions and densities obtained by the DOS and RMF theories are essentially different. The nucleon densities of the RMF theory contradict to knowledge about distribution of the proton and neutron densities inside the nuclei obtained from experimental data. This indicates that $g$ and $f$ have no sense of the wave functions of quantum physics. But, $h$ provides proper description of quantum properties of nucleons inside the nucleus. (3) We calculate meson function $w^0$ and potential $V_w$ in RMF theory based on the found nucleon density. (4) $f$ and $g$ are not solutions of Dirac equation with $V_w$. If the meson theory describes quantum properties of nucleus well, then a difference between $V_w$ and $V_{RMF}$ should be as small as possible. We introduce new quantum corrections characterizing difference between these potentials. We find that (a) The function $w^0$ should be reinforced strongly, (b) The corrections are necessary to describe the quantum properties of the nuclei.

   ↳ nucl-thhep-thnucl-exquant-ph0 citations
4. 04*

   Influence of short-range correlations in neutrino-nucleus scattering

   Tom Van Cuyck🇧🇪 · Natalie Jachowicz🇧🇪 · Raúl González Jiménez🇧🇪 · Marco Martini🇧🇪 · Vishvas Pandey🇧🇪 · Jan Ryckebusch🇧🇪 · Nils Van Dessel🇧🇪

   Background: Nuclear short-range correlations (SRCs) are corrections to mean-field wave functions connected with the short-distance behavior of the nucleon-nucleon interaction. These SRCs provide corrections to lepton- nucleus cross sections as computed in the impulse approximation (IA). Purpose: We want to investigate the influence of SRCs on the one-nucleon (1N) and two-nucleon (2N) knockout channel for muon-neutrino induced processes on a ${}^{12}$C target at energies relevant for contemporary measurements. Method: The model adopted in this work, corrects the impulse approximation for SRCs by shifting the com- plexity induced by the SRCs from the wave functions to the operators. Due to the local character of the SRCs, it is argued that the expansion of these operators can be truncated at a low order. Results: The model is compared with electron-scattering data, and two-particle two-hole responses are presented for neutrino scattering. The contributions from the vector and axial-vector parts of the nuclear current as well as the central, tensor and spin-isospin part of the SRCs are studied. Conclusions: Nuclear SRCs affect the 1N knockout channel and give rise to 2N knockout. The exclusive neutrino-induced 2N knockout cross section of SRC pairs is shown and the 2N knockout contribution to the QE signal is calculated. The strength occurs as a broad background which extends into the dip region.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2016)·68 citations
5. 05*

   Baryon transition form factors at the pole

   L. Tiator🇩🇪 · M. Döring🇺🇸 · R. L. Workman🇺🇸 · M. Hadžimehmedović🇧🇦 · H. Osmanović🇧🇦 · R. Omerović🇧🇦 · J. Stahov🇧🇦 · A. Švarc🇭🇷

   Electromagnetic resonance properties are uniquely defined at the pole and do not depend on the separation of the resonance from background or the decay channel. Photon-nucleon branching ratios are nowadays often quoted at the pole, and we generalize the considerations to the case of virtual photons. We derive and compare relations for nucleon to baryon transition form factors both for the Breit-Wigner and the pole positions. Using the MAID2007 and SAID SM08 partial wave analyses of pion electroproduction data, we compare the $G_M$, $G_E$, and $G_C$ form factors for the $\Delta (1232)$ resonance excitation at the Breit-Wigner resonance and pole positions up to $Q^2=5$ GeV${}^2$. We also explore the $E/M$ and $S/M$ ratios as functions of $Q^2$. For pole and residue extraction, we apply the Laurent + Pietarinen method.

   ↳ nucl-thnucl-exPRC(2016)·21 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.