Tue·Dec 16, 2014Tuesday·December 16, 2014

1. 01*

   Symmetry energy dependence of long timescale isospin transport

   K. Stiefel🇺🇸 · Z. Kohley🇺🇸 · R. T. deSouza🇺🇸 · S. Hudan🇺🇸 · K. Hammerton

   Isospin transport occurring within dinuclear projectile-like fragments (PLFs) produced in heavy- ion collisions is explored as a probe of the nuclear symmetry energy. Within the framework of the Constrained Molecular Dynamics model (CoMD), the existence of the long-lived dinuclear PLFs, for up to 800 fm/c, is observed. It is demonstrated that changes in the <N/Z> of the two fragments resulting from the breakup of the dinuclear PLF is due to isospin transport. The rate of the transport between the two fragments is shown to be dependent on the slope of the symmetry energy at saturation density. Comparison of the CoMD calculations with experimental data establish that the evolution of <N/Z> could be used to constrain the density dependence of the symmetry energy.

   nucl-exnucl-thPRC(2014)·17 citations
2. 02*

   Influence of $\varphi$ mesons on negative kaons in Ni+Ni collisions at 1.91A GeV beam energy

   K. Piasecki🇵🇱 · N. Herrmann🇩🇪 · R. Averbeck🇩🇪 · A. Andronic🇩🇪 · V. Barret🇫🇷 · Z. Basrak🇭🇷 · N. Bastid🇫🇷 · M.L. Benabderrahmane🇩🇪 · M. Berger🇩🇪 · P. Buehler🇦🇹 · M. Cargnelli🇦🇹 · R. Čaplar🇭🇷 and 54 other authors

   $\varphi$ and K${}^{-}$ mesons from Ni+Ni collisions at the beam energy of 1.91A GeV have been measured by the FOPI spectrometer, with a trigger selecting central and semi-central events amounting to 51% of the total cross section. The phase space distributions, and the total yield of K${}^{-}$, as well as the kinetic energy distribution and the total yield of $\varphi$ mesons are presented. The $\varphi$\K${}^{-}$ ratio is found to be $0.44\pm 0.07(\text{stat}{)}_{-0.12}^{+0.18}(\text{syst})$, meaning that about 22% of K${}^{-}$ mesons originate from the decays of $\varphi$ mesons, occurring mostly in vacuum. The inverse slopes of direct kaons are up to about 15 MeV larger than the ones extracted within the one-source model, signalling that a considerable share of gap between the slopes of K${}^{+}$ and K${}^{-}$ could be explained by the contribution of $\varphi$ mesons to negative kaons.

   nucl-exPRC(2015)·22 citations
3. 03*

   Centrality and rapidity dependence of inclusive jet production in $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV proton-lead collisions with the ATLAS detector

   ATLAS Collaboration

   Measurements of the centrality and rapidity dependence of inclusive jet production in $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV proton--lead ($p$+Pb) collisions and the jet cross-section in $\sqrt{s}=2.76$ TeV proton--proton collisions are presented. These quantities are measured in datasets corresponding to an integrated luminosity of 27.8 nb${}^{-1}$ and 4.0 pb${}^{-1}$, respectively, recorded with the ATLAS detector at the Large Hadron Collider in 2013. The $p$+Pb collision centrality was characterised using the total transverse energy measured in the pseudorapidity interval $-4.9<\eta <-3.2$ in the direction of the lead beam. Results are presented for the double-differential per-collision yields as a function of jet rapidity and transverse momentum ($p_{\mathrm{T}}$) for minimum-bias and centrality-selected $p$+Pb collisions, and are compared to the jet rate from the geometric expectation. The total jet yield in minimum-bias events is slightly enhanced above the expectation in a $p_{\mathrm{T}}$-dependent manner but is consistent with the expectation within uncertainties. The ratios of jet spectra from different centrality selections show a strong modification of jet production at all $p_{\mathrm{T}}$ at forward rapidities and for large $p_{\mathrm{T}}$ at mid-rapidity, which manifests as a suppression of the jet yield in central events and an enhancement in peripheral events. These effects imply that the factorisation between hard and soft processes is violated at an unexpected level in proton-nucleus collisions. Furthermore, the modifications at forward rapidities are found to be a function of the total jet energy only, implying that the violations may have a simple dependence on the hard parton-parton kinematics.

   ↳ hep-exnucl-exPLB(2015)·222 citations
4. 04*

   Decay and structure of the Hoyle state

   Souichi Ishikawa

   The first $0^{+}$ resonant state of the ${}^{12}$C nucleus ${}^{12}$C$(0_2^{+})$, so called the Hoyle state, is investigated in a three-$\alpha$-particle (3-$\alpha$) model. A wave function for the photodisintegration reaction of a ${}^{12}$C bound state to 3-$\alpha$ final states is defined and calculated by the Faddeev three-body formalism, in which three-body bound- and continuum states are treated consistently. From the wave function at the Hoyle state energy, I calculated distributions of outgoing $\alpha$-particles and density distributions at interior region of the Hoyle state. Results show that a process through a two-$\alpha$ resonant state is dominant in the decay and contributions of the rest process are very small, less than 1 \%. There appear some peaks in the interior density distribution corresponding to configurations of an equilateral- and an isosceles triangles. It turns out that these results are obtained independently of the choice of $\alpha$-particle interaction models, when they are made to reproduce the Hoyle state energy.

   ↳ nucl-thnucl-exPRC(2014)·56 citations
5. 05*

   Triaxially deformed relativistic point-coupling model for $\Lambda$ hypernuclei: a quantitative analysis of hyperon impurity effect on nuclear collective properties

   W. X. Xue🇨🇳 · J. M. Yao🇯🇵 · K. Hagino🇯🇵 · Z. P. Li🇨🇳 · H. Mei🇯🇵 · Y. Tanimura🇫🇷

   The impurity effect of hyperon on atomic nuclei has received a renewed interest in nuclear physics since the first experimental observation of appreciable reduction of $E2$ transition strength in low-lying states of hypernucleus ${}_{\Lambda }^7$Li. Many more data on low-lying states of $\Lambda$ hypernuclei will be measured soon for $sd$-shell nuclei, providing good opportunities to study the $\Lambda$ impurity effect on nuclear low-energy excitations. We carry out a quantitative analysis of $\Lambda$ hyperon impurity effect on the low-lying states of $sd$-shell nuclei at the beyond-mean-field level based on a relativistic point-coupling energy density functional (EDF), considering that the $\Lambda$ hyperon is injected into the lowest positive-parity (${\Lambda }_s$) and negative-parity (${\Lambda }_p$) states. We adopt a triaxially deformed relativistic mean-field (RMF) approach for hypernuclei and calculate the $\Lambda$ binding energies of hypernuclei as well as the potential energy surfaces (PESs) in $(\beta ,\gamma )$ deformation plane. We also calculate the PESs for the $\Lambda$ hypernuclei with good quantum numbers using a microscopic particle rotor model (PRM) with the same relativistic EDF. The triaxially deformed RMF approach is further applied in order to determine the parameters of a five-dimensional collective Hamiltonian (5DCH) for the collective excitations of triaxially deformed core nuclei. Taking ${}_{\Lambda }^{25,27}$Mg and ${}_{\Lambda }^{31}$Si as examples, we analyse the impurity effects of ${\Lambda }_s$ and ${\Lambda }_p$ on the low-lying states of the core nuclei...

   ↳ nucl-thnucl-exPRC(2015)·32 citations
6. 06*

   Effect of the Jet Production on Pseudorapidity, Transverse Momentum and Transverse Mass Distributions of Charged Particles Produced in pp-Collisions at Tevatron Energy

   Ali Zaman🇵🇰 · Mais Suleymanov🇵🇰 · Muhammad Ajaz🇵🇰 · Kamal Hussain Khan🇵🇰

   We investigate the effects of jet production on the following parameters: pseudorapidity, transverse momentum and transverse mass distributions of secondary charged particles produced in pp-collisions at 1.8 TeV, using the HIJING code. These distributions are analyzed for the whole range and for selected six regions of the polar angle as a function of different number of jets. The obtained simulation results for these parameters are interpreted and discussed in connection to the increase observed in the multiplicity of secondary charged particles as a result of its multi-jet dependence and are also discussed in comparison with the experimental results from the CDF Collaboration.

   ↳ hep-exnucl-exCPC(2015)·2 citations
7. 07*

   Recent results from NA61/SHINE

   Marek Gazdzicki (for the NA61/SHINE Collaboration)🇩🇪

   This paper briefly presents the NA61/SHINE facility at the CERN SPS and its measurements motivated by physics of strong interactions, neutrinos and cosmic rays.

   ↳ hep-exnucl-exEPJ Web Conf.(2015)·9 citations
8. 08*

   Recent Advances and Open Questions in Neutrino-induced Quasi-elastic Scattering and Single Photon Production

   G. T. Garvey🇺🇸 · D. A. Harris🇺🇸 · H. A. Tanaka🇨🇦 · R. Tayloe🇺🇸 · G. P. Zeller🇺🇸

   The study of neutrino-nucleus interactions has recently seen rapid development with a new generation of accelerator-based neutrino experiments employing medium and heavy nuclear targets for the study of neutrino oscillations. A few unexpected results in the study of quasi-elastic scattering and single photon production have spurred a revisiting of the underlying nuclear physics and connections to electron-nucleus scattering. A thorough understanding and resolution of these issues is essential for future progress in the study of neutrino oscillations. A recent workshop hosted by the Institute of Nuclear Theory at the University of Washington (INT-13-54W) examined experimental and theoretical developments in neutrino-nucleus interactions and related measurements from electron and pion scattering. We summarize the discussions at the workshop pertaining to the aforementioned issues in quasi-elastic scattering and single photon production, particularly where there was consensus on the highest priority issues to be resolved and the path towards resolving them.

   ↳ hep-exnucl-exnucl-thPhys.Rept.(2015)·40 citations
9. 09*

   Precision nucleon-nucleon potential at fifth order in the chiral expansion

   E. Epelbaum🇩🇪 · H. Krebs🇩🇪 · U.-G. Meißner🇩🇪

   We present a nucleon-nucleon potential at fifth order in chiral effective field theory. We find a substantial improvement in the description of nucleon-nucleon phase shifts as compared to the fourth-order results of Ref. [E. Epelbaum, H. Krebs, U.-G. Meißner, arXiv:1412.0142 [nucl-th]]. This provides clear evidence of the corresponding two-pion exchange contributions with all low-energy constants being determined from pion-nucleon scattering. The fifth-order corrections to nucleon-nucleon observables appear to be of a natural size which confirms the good convergence of the chiral expansion for nuclear forces. Furthermore, the obtained results provide strong support for the novel way of quantifying the theoretical uncertainty due to the truncation of the chiral expansion proposed in Ref. [E. Epelbaum, H. Krebs, U.-G. Meißner, arXiv:1412.0142 [nucl-th]]. Our work opens up new perspectives for precision ab initio calculations in few- and many-nucleon systems and is especially relevant for ongoing efforts towards a quantitative understanding the structure of the three-nucleon force in the framework of chiral effective field theory.

   ↳ nucl-thhep-phnucl-exPRL(2015)·444 citations
10. 10*

    Alternative ansatz to wounded nucleon and binary collision scaling in high-energy nuclear collisions

    J. Scott Moreland🇺🇸 · Jonah E. Bernhard🇺🇸 · Steffen A. Bass🇺🇸

    We introduce TRENTO, a new parametric initial condition model for high-energy nuclear collisions based on eikonal entropy deposition via a "reduced thickness" function. The model simultaneously describes experimental proton-proton, proton-nucleus, and nucleus-nucleus multiplicity distributions, and generates nucleus-nucleus eccentricity harmonics consistent with experimental flow constraints. In addition, the model is compatible with ultra-central uranium-uranium data unlike existing models that include binary collision terms.

    ↳ nucl-thhep-phnucl-exPRC(2015)·602 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.