Tue·Dec 2, 2014Tuesday·December 2, 2014

1. 01*

   Toroidal high-spin isomers in light nuclei with N not equal to Z

   Andrzej Staszczak🇵🇱 · Cheuk-Yin Wong🇺🇸

   The combined considerations of both the bulk liquid-drop-type behavior and the quantized aligned rotation with cranked Skyrme-Hartree-Fock approach revealed previously [Phys. Lett. B 738 (2014) 401] that even-even, N=Z, toroidal high-spin isomeric states have general occurrences for light nuclei with A between 28 and 52. We find that in this mass region there are in addition N not equal to Z toroidal high-spin isomers when the single-particle shells for neutrons and protons occur at the same cranked frequency $\hslash \omega$. Examples of N not equal to Z toroidal high-spin isomers, ${}_{16}^{36}$S${}_{20}$($I$=74$\hslash$) and ${}_{18}^{40}$Ar${}_{22}$($I$=80,102$\hslash$), are located and examined. The systematic properties of these N not equal to Z toroidal high-spin isomers fall into the same regular (muti-particle)-(muti-hole) patterns as other N=Z toroidal high-spin isomers.

   nucl-thPhys.Scripta(2015)·15 citations
2. 02*

   Nucleon-nucleon scattering with the Complex Scaling Method and realistic interactions

   G. Papadimitriou🇺🇸 · J. P. Vary🇺🇸

   We demonstrate the validity of the complex scaling method for realistic strong, non-local, nucleon- nucleon interactions by comparing the deuteron bound state and nucleon-nucleon scattering phase shifts with results from other high-precision methods. This opens a pathway for the simultaneous ab initio solutions of the nuclear bound and scattering problems within a unified framework.

   nucl-thPRC(2015)·13 citations
3. 03*

   Coherent pi0-pi0 photoproduction on lightest nuclei

   M. Egorov🇷🇺 · A. Fix🇷🇺

   Coherent photoproduction of two neutral pions on the deuteron and ^3He is calculated. The isoscalar and isovector parts of the elementary photoproduction amplitude was determined by fitting the measured total cross section on protons and neutrons. The dependence of the cross section on the isospin of the target nucleus is discussed.

   nucl-thNPA(2015)·22 citations
4. 04*

   On formation of equation of state of evolving quantum field

   A.V. Leonidov🇷🇺 · A.A. Radovskaya🇷🇺

   Stylized model of evolution of matter created in ultra relativistic heavy ion collisions is considered. Systematic procedure of computing quantum corrections in the framework of Keldysh formalism is formulated. Analytical expressions for formation of equations of state taking into account leading quantum corrections is worked out, complete description of subleasing corrections and analytical expressions for some of them is presented.

   nucl-thJETP Lett.(2015)·11 citations
5. 05*

   Improved chiral nucleon-nucleon potential up to next-to-next-to-next-to-leading order

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

   We present improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-to-next-to-leading order. We argue that the nonlocal momentum-space regulator employed in the two-nucleon potentials of Refs. [E. Epelbaum, W. Gloeckle, U.-G. Meißner, Nucl. Phys. A747 (2005) 362], [D.R. Entem, R. Machleidt, Phys. Rev. C68 (2003) 041001] is not the most efficient choice, in particular since it affects the long-range part of the interaction. We are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude. The new potentials do not require the additional spectral function regularization employed in Ref. [E. Epelbaum, W. Gloeckle, U.-G. Meißner, Nucl. Phys. A747 (2005) 362] to cut off the short-range components of the two-pion exchange and make use of the low-energy constants c_i and d_i determined from pion-nucleon scattering without any fine tuning. We discuss in detail the construction of the new potentials and convergence of the chiral expansion for two-nucleon observables. We also introduce a new procedure for estimating the theoretical uncertainty from the truncation of the chiral expansion that replaces previous reliance on cutoff variation.

   nucl-thEPJA(2015)·546 citations
6. 06*

   Resonance-state properties from a phase shift analysis with the $S$-matrix pole method and the effective-range method

   B.F. Irgaziev🇵🇰 · Yu.V. Orlov🇺🇸

   Asymptotic normalization coefficients (ANCs) are fundamental nuclear constants playing an important role in nuclear physics and astrophysics. We derive a new useful relationship between ANC of the Gamow radial wave function and the renormalized (due to the Coulomb interaction) Coulomb-nuclear partial scattering amplitude. We use an analytical approximation in the form of a series for the nonresonant part of the phase shift which can be analytically continued to the point of an isolated resonance pole in the complex plane of the momentum. Earlier, this method which we call the $S$-matrix pole method was used by us to find the resonance pole energy. We find the corresponding fitting parameters for the ${}^5\mathrm{He},{}^5\mathrm{Li}$, and ${}^{16}\mathrm{O}$ concrete resonance states. Additionally, based on the theory of the effective range, we calculate the parameters of the $p_{3/2}$ and $p_{1/2}$ resonance states of the nuclei ${}^5\mathrm{He}$ and ${}^5\mathrm{Li}$ and compare them with the results obtained by the $S$-matrix pole method. ANC values are found which can be used to calculate the reaction rate through the ${}^{16}\mathrm{O}$ resonances which lie slightly above the threshold for the ${\alpha }^{12}\mathrm{C}$ channel.

   nucl-thPRC(2015)·17 citations
7. 07*

   Pion-assisted $N\Delta$ and $\Delta \Delta$ dibaryons, and beyond

   Avraham Gal🇮🇱

   Experimental evidence for $I(J^P)=0(3^{+})$ $\Delta \Delta$ dibaryon ${\mathcal{D}}_{03}(2370)$ has been presented recently by the WASA-at-COSY Collaboration. Here I review new hadronic-basis Faddeev calculations of $L=0$ nonstrange pion-assisted $N\Delta$ and $\Delta \Delta$ dibaryon candidates. These calculations are so far the only ones to reproduce the relatively small ${\mathcal{D}}_{03}(2370)$ width of 70--80 MeV. Predictions are also given for the location and width of ${\mathcal{D}}_{30}$, the $I(J^P)=3(0^{+})$ exotic partner of ${\mathcal{D}}_{03}(2370)$. Extensions to strangeness $\mathcal{S}=-1$ dibaryons are briefly discussed.

   nucl-thhep-phnucl-exHyperfine Interact.(2015)·5 citations
8. 08*

   Impact of the phonon coupling on the photon strength function

   Oleg Achakovskiy · Alexander Avdeenkov · Stephane Goriely🇧🇪 · Sergei Kamerdzhiev🇷🇺 · Siegfried Krewald🇩🇪

   The pygmy dipole resonances and photon strength functions in stable and unstable Ni and Sn isotopes are calculated within the microscopic self-consistent version of the extended theory of finite fermi systems which includes phonon coupling effects.The Skyrme forces SLy4 is used. A pygmy dipole resonance in ${}^{72}$Ni is predicted at the mean energy of 12.4 MeV exhausting 25.7\% of the total energy-weighted sum rule. The microscopically obtained photon E1 strength functions are compared with available experimental data and used to calculate nuclear reaction properties. Average radiative widths and radiative neutron capture cross sections have been calculated taking the phonon coupling into account as well as the uncertainties caused by various microscopic level density models. In all three quantities considered, the contribution of phonon coupling turned out to be significant and is found necessary to explain available experimental data.

   nucl-thnucl-exPRC(2015)·26 citations
9. 09*

   Viscosity of neutron star matter and $r$-modes in rotating pulsars

   E.E. Kolomeitsev🇸🇰 · D.N. Voskresensky🇷🇺

   We study viscosity of the neutron star matter and $r$-mode instability in rotating neutron stars. Contributions to the shear and bulk viscosities from various processes are calculated with account of in-medium modifications of the nucleon-nucleon interaction. A softening of the pion mode and a possibility of the pion condensation are included. The nucleon pairing is incorporated. In the shear viscosity we include the lepton contribution calculated with account of the Landau damping in the photon exchange, the nucleon contribution described by the medium-modified one pion exchange, and other terms, such as the novel phonon contribution in the 1S${}_0$ superfluid neutron phase, and the neutrino term in the neutrino opacity region. The nucleon shear viscosity depends on the density rather moderately and proves to be much less than the lepton term. Among the terms contributing to the bulk viscosity, the term from the medium modified Urca reactions possesses strongest density dependence because of the pion softening. Contributions to the bulk viscosity arising from other reactions induced by charged weak currents are included. The radiative bulk viscosity induced by charged and neutral weak currents in the region of the neutrino transparency of the star is also calculated with account for in-medium effects. The computed frequency boundary of the $r$-mode stability for the stars with the mass $\ge 1.8M_{\odot }$ proves to be above the frequencies of all rotating young pulsars. To explain the stability of rapid rotation of old pulsars in X-ray binaries we propose a novel efficient mechanism associated with appearance of condensates of low-lying modes of bosonic excitations with finite momentum and/or with an enhancement of the inhomogeneous pion/kaon condensates in some parts of the star, if the angular velocity exceeds a critical value.

   nucl-thPRC(2015)·52 citations
10. 10*

    Chiral three-nucleon forces and the evolution of correlations along the oxygen isotopic chain

    A. Cipollone (Surrey, CMCC)🇬🇧 · C. Barbieri (Surrey)🇬🇧 · P. Navrátil (TRIUMF)🇨🇦

    The impact of three-nucleon forces (3NFs) along the oxygen chain is investigated for the spectral distribution for attachment and removal of a nucleon, spectroscopic factors and matter radii. We employ self-consistent Green's function (SCGF) theory which allows a comprehensive calculation of the single particle spectral function. For the closed subshell isotopes, ${}^{14}$O, ${}^{16}$O, ${}^{22}$O, ${}^{24}$O and ${}^{28}$O, we perform calculations with the Dyson-ADC(3) method. The remaining open shell isotopes are studied using the newly developed Gorkov-SCGF formalism up to second order. We produce plots for the full-fledged spectral distributions. The spectroscopic factors for the dominant quasiparticle peaks are found to depend very little on the leading order (NNLO) chiral 3NFs. The latters have small impact on the calculated matter radii, which, however are consistently obtained smaller than experiment. Similarly, single particle spectra tend to be diluted with respect to experiment. This effect might hinder, to some extent, the onset of correlations and screen the quenching of calculated spectroscopic factors. The most important effects of 3NFs is thus the fine tuning of the energies for the dominant quasiparticle states, which govern the shell evolution and the position of driplines. Although present chiral NNLO 3NFs interactions do reproduce the binding energies correctly in this mass region, the details of the nuclear wave function remain at odd with the experiment showing too small radii and a too dilute single particle spectrum, similar to what already pointed out for larger masses. This suggests a lack of repulsion in the present model of NN+3N interactions which is mildly apparent already for masses in the A=14--28 range.

    nucl-thPRC(2015)·90 citations
11. 11*

    Chiral symmetry breaking in continuum QCD

    Mario Mitter🇩🇪 · Jan M. Pawlowski🇩🇪 · Nils Strodthoff🇩🇪

    We present a quantitative analysis of chiral symmetry breaking in two-flavour continuum QCD in the quenched limit. The theory is set-up at perturbative momenta, where asymptotic freedom leads to precise results. The evolution of QCD towards the hadronic phase is achieved by means of dynamical hadronisation in the non-perturbative functional renormalisation group approach. We use a vertex expansion scheme based on gauge-invariant operators and discuss its convergence properties and the remaining systematic errors. In particular we present results for the quark propagator, the full tensor structure and momentum dependence of the quark-gluon vertex, and the four-fermi scatterings.

    ↳ hep-phhep-thnucl-thPRD(2015)·298 citations
12. 12*

    Transport Coefficients in Yang--Mills Theory and QCD

    Nicolai Christiansen🇩🇪 · Michael Haas🇩🇪 · Jan M. Pawlowski🇩🇪 · Nils Strodthoff🇩🇪

    We calculate the shear viscosity over entropy density ratio $\eta /s$ in Yang--Mills theory from the Kubo formula using an exact diagrammatic representation in terms of full propagators and vertices using gluon spectral functions as external input. We provide an analytic fit formula for the temperature dependence of $\eta /s$ over the whole temperature range from a glueball resonance gas at low temperatures, to a high-temperature regime consistent with perturbative results. Subsequently we provide a first estimate for $\eta /s$ in QCD.

    ↳ hep-phhep-thnucl-thPRL(2015)·138 citations
13. 13*

    Femtoscopic signature of strong radial flow in high-multiplicity $pp$ collisions

    Yuji Hirono🇺🇸 · Edward Shuryak🇺🇸

    Hydrodynamic simulations are used to calculate the identical pion HBT radii, as a function of the pair momentum $k_{\mathrm{T}}$. This dependence is sensitive to the magnitude of the collective radial flow in the transverse plane, and thus comparison to ALICE data enables us to derive its magnitude. By using hydro solutions with variable initial parameters we conclude that in this case fireball explosions start with a very small initial size, well below 1 $\mathrm{fm}$.

    ↳ hep-phnucl-thPRC(2015)·23 citations
14. 14*

    Momentum sharing in imbalanced Fermi systems

    O. Hen · M. Sargsian · L.B. Weinstein · E. Piasetzky · H. Hakobyan · D. W. Higinbotham · M. Braverman · W.K. Brooks · S. Gilad · K. P. Adhikari · J. Arrington · G. Asryan and 129 other authors

    The atomic nucleus is composed of two different kinds of fermions, protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority fermions (usually neutrons) to have a higher average momentum. Our high-energy electron scattering measurements using 12C, 27Al, 56Fe and 208Pb targets show that, even in heavy neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few body systems to neutron stars and may also be observable experimentally in two-spin state, ultra-cold atomic gas systems.

    ↳ nucl-excond-mat.quant-gasnucl-thScience(2014)·341 citations
15. 15*

    Status of some P-wave baryon resonances and importance of inelastic channels

    Volker D. Burkert🇺🇸 · Hiroyuki Kamano🇯🇵 · Eberhard Klempt🇩🇪 · Deborah Ronchen🇩🇪 · Andrey V. Sarantsev🇩🇪 · Toru Sato🇯🇵 · Alfred Svarc🇭🇷 · Lothar Tiator🇩🇪 · Ron L. Workman🇺🇸

    We analyze the current status of three P-wave baryon states $N(1710){1/2}^{+}$, $N(1900){3/2}^{+}$, and $\Delta (1600){3/2}^{+}$ as given in the Review of Particles Physics (RPP). Since the evidence for a particle's existence is linked to its RPP "star" rating, we discuss its subjective present definition. We also present the accumulating evidence supporting these states and give our new "star" rating recommendations.

    ↳ nucl-exnucl-th9 citations
16. 16*

    The chiral magnetic effect in heavy-ion collisions from event-by-event anomalous hydrodynamics

    Yuji Hirono🇺🇸 · Tetsufumi Hirano🇯🇵 · Dmitri E. Kharzeev🇺🇸

    The (3+1)D relativistic hydrodynamics with chiral anomaly is used to obtain a quantitative description of the chiral magnetic effect (CME) in heavy-ion collisions. We find that the charge-dependent hadron azimuthal correlations are sensitive to the CME, and that the experimental observations are consistent with the presence of the effect.

    ↳ hep-phnucl-exnucl-th83 citations
17. 17*

    Initial state in relativistic nuclear collisions and Color Glass Condensate

    F. Gelis🇫🇷

    In this talk, I discuss recent works related to the pre-hydrodynamical stages of ultra-relativistic heavy ion collisions.

    ↳ hep-phnucl-thNPA(2014)·10 citations
18. 18*

    Heavy flavours in high-energy nuclear collisions: quenching, flow and correlations

    A. Beraudo🇮🇹 · A. De Pace🇮🇹 · M. Monteno🇮🇹 · M. Nardi🇮🇹 · F. Prino🇮🇹

    We present results for the quenching, elliptic flow and azimuthal correlations of heavy flavour particles in high-energy nucleus-nucleus collisions obtained through the POWLANG transport setup, developed in the past to study the propagation of heavy quarks in the Quark-Gluon Plasma and here extended to include a modeling of their hadronization in the presence of a medium. Hadronization is described as occurring via the fragmentation of strings with endpoints given by the heavy (anti-)quark Q(Qbar) and a thermal parton $qbar(q)$ from the medium. The flow of the light quarks is shown to affect significantly the R_AA} and v_2 of the final D mesons, leading to a better agreement with the experimental data.

    ↳ hep-phnucl-thJ.Phys.Conf.Ser.(2015)·1 citation
19. 19*

    Chiral Superfluidity for QCD

    Tigran Kalaydzhyan🇺🇸

    We argue that the strongly coupled quark-gluon plasma formed at LHC and RHIC can be considered as a chiral superfluid. The "normal" component of the fluid is the thermalized matter in common sense, while the "superfluid" part consists of long wavelength (chiral) fermionic states moving independently. We use the bosonization procedure with a finite cut-off and obtain a dynamical axion-like field out of the chiral fermionic modes. Then we use relativistic hydrodynamics for macroscopic description of the effective theory obtained after the bosonization. Finally, solving the hydrodynamic equations in gradient expansion, we find that in the presence of external electromagnetic fields or rotation the motion of the "superfluid" component gives rise to the chiral magnetic, chiral vortical, chiral electric and dipole wave effects. Latter two effects are specific for a two-component fluid, which provides us with crucial experimental tests of the model.

    ↳ hep-phhep-thnucl-th1 citation
20. 20*

    Current conservation in electrodisintegration of a bound system in the Bethe-Salpeter approach

    V.A. Karmanov🇷🇺 · J. Carbonell🇫🇷

    Using our solutions of the Bethe-Salpeter equation with OBE kernel in Minkowski space both for the bound and scattering states, we calculate the transition form factors for electrodisintegration of the bound system which determine the electromagnetic current J of this process. Special emphasis is put on verifying the gauge invariance which should manifest itself in the current conservation. We find that for any value of the momentum transfer q the contributions of the plane wave and the final state interaction to the quantity J.q cancel each other thus providing J.q=0. However, this cancellation is obtained only if the initial Bethe-Salpeter amplitude (bound state), the final one (scattering state) and the current operator are strictly consistent with each other. A reliable result for the transition form factor can be found only in this case.

    ↳ hep-phnucl-thFew Body Syst.(2015)·1 citation

* 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.