Mon·Dec 1, 2014Monday·December 1, 2014

1. 01*

   Energy and mass-number dependence of hadron-nucleus total reaction cross sections

   Akihisa Kohama · Kei Iida🇯🇵 · Kazuhiro Oyamatsu🇯🇵

   We systematically analyze nuclear reaction data that are sensitive to nuclear size, namely, proton-nucleus total reaction cross sections and differential elastic cross sections, using a phenomenological black-sphere approximation of nuclei that we are developing. In this framework, the radius of the black sphere is found to be a useful length scale that simultaneously accounts for the observed proton-nucleus total reaction cross section and first diffraction peak in the proton elastic differential cross section. This framework is expected to be applicable to any kind of projectile that is strongly attenuated in the nucleus. On the basis of a cross-section formula constructed within this framework, we find that a less familiar $A^{1/6}$ dependence plays a crucial role in describing the energy dependence of proton-nucleus total reaction cross sections.

   nucl-thJ.Phys.Soc.Jap.(2016)·14 citations
2. 02*

   Advances in Basis Light-front Quantization

   Xingbo Zhao🇺🇸

   Basis Light-front Quantization has been developed as a first-principles nonperturbative approach to quantum field theory. In this article we report our recent progress on the applications to the single electron and the positronium system in QED. We focus on the renormalization procedure in this method.

   nucl-thhep-phFew Body Syst.(2015)·25 citations
3. 03*

   Three-dimensional mesh calculations for covariant density functional theory

   Y. Tanimura🇯🇵 · K. Hagino🇯🇵 · H. Z. Liang🇯🇵

   In contrast to the non-relativistic approaches, three-dimensional (3D) mesh calculations for the {\it relativistic} density functional theory have not been realized because of the challenges of variational collapse and fermion doubling. We overcome these difficulties by developing a novel method based on the ideas of Wilson fermion as well as the variational principle for the inverse Hamiltonian. We demonstrate the applicability of this method by applying it to ${}^{16}$O, ${}^{24}$Mg, and ${}^{28}$Si nuclei, providing detailed explanation on the formalism and verification of numerical implementation.

   nucl-thPTEP(2015)·29 citations
4. 04*

   Wilson coefficients and four-quark condensates in QCD sum rules for medium modifications of $D$ mesons

   Thomas Buchheim🇩🇪 · Thomas Hilger🇦🇹 · Burkhard Kampfer🇩🇪

   Wilson coefficients of light four-quark condensates in QCD sum rules are evaluated for pseudo-scalar $D$ mesons, thus, pushing the sum rules toward mass dimension six. Contrary to the situation for $\bar{q}q$ mesons the impact of the four-quark condensates for vacuum as well as in-medium situations is found to be rather small within the Borel window used in previous analyses. The complete four-quark condensate contributions enable to identify candidates for an order parameter of spontaneous chiral symmetry breaking/restoration as well as to evaluate stability criteria of operator product expansions.

   nucl-thhep-phPRC(2015)·24 citations
5. 05*

   A New Hadron Spectroscopy

   Stephen Lars Olsen🇰🇷

   QCD-motivated models for hadrons predict an assortment of "exotic" hadrons that have structures that are more complex than the quark-antiquark mesons and three-quark baryons of the original quark-parton model. These include pentaquark baryons, the six-quark H-dibaryon, and tetraquark, hybrid and glueball mesons. Despite extensive experimental searches, no unambiguous candidates for any of these exotic configurations have been identified. On the other hand, a number of meson states, one that seems to be a proton-antiproton bound state, and others that contain either charmed-anticharmed quark pairs or bottom-antibottom quark pairs, have been recently discovered that neither fit into the quark-antiquark meson picture nor match the expected properties of the QCD-inspired exotics. Here I briefly review results from a recent search for the H-dibaryon, and discuss some properties of the newly discovered states --the proton-antiproton state and the so-called XYZ mesons-- and compare them with expectations for conventional quark-antiquark mesons and the predicted QCD-exotic states.

   ↳ hep-exhep-phnucl-exnucl-thFront.Phys.(Beijing)(2015)·112 citations
6. 06*

   Analytical and numerical Gubser solutions of the second-order hydrodynamics

   Long-Gang Pang🇨🇳 · Yoshitaka Hatta🇯🇵 · Xin-Nian Wang🇨🇳 · Bo-Wen Xiao🇨🇳

   Evolution of quark-gluon plasma (QGP) near equilibrium can be described by the second-order relativistic viscous hydrodynamic equations. Consistent and analytically verifiable numerical solutions are critical for phenomenological studies of the collective behavior of QGP in high-energy heavy-ion collisions. A novel analytical solution based on the conformal Gubser flow which is a boost-invariant solution with transverse fluid velocity is presented. Due to the non-linear nature of the equation, the analytical solution is non-perturbative and exhibits features that are rather distinct from solutions to usual linear hydrodynamic equations. It is used to verify with high precision the numerical solution with a newly developed state-of-the-art $(3+1)$-dimensional second-order viscous hydro code (CLVisc). The perfect agreement between the analytical and numerical solutions demonstrates the reliability of the numerical simulations with the second-order viscous corrections. This lays the foundation for future phenomenological studies that allow one to gain access to the second-order transport coefficients.

   ↳ hep-phhep-thnucl-thPRD(2015)·82 citations
7. 07*

   Multiparticle production in nuclear collisions using effective-energy approach

   Aditya Nath Mishra🇮🇳 · Raghunath Sahoo🇮🇳 · Edward K.G. Sarkisyan🇨🇭 · Alexander S. Sakharov🇨🇭

   The dependencies of charged particle pseudorapidity density and transverse energy pseudorapidity density at midrapidity on the collision energy and on the number of nucleon participants, or centrality, measured in nucleus-nucleus collisions are studied in the energy range spanning a few GeV to a few TeV per nucleon. The study is based on the earlier proposed model, combining the constituent quark picture together with Landau relativistic hydrodynamics and shown to interrelate the measurements from different types of collisions. Within this picture, the dependence on the number of participants in heavy-ion collisions are found to be well described in terms of the effective energy defined as a centrality-dependent fraction of the collision energy. The effective energy approach is shown to reveal a similarity in the energy dependence for the most central and centrality data in the entire available energy range. Predictions are made for the forthcoming higher-energy measurements in heavy-ion collisions at the LHC.

   ↳ hep-phhep-exnucl-exnucl-thEPJ Web Conf.(2015)·0 citations
8. 08*

   Neutrino-nucleus CCQE-like scattering

   J. Nieves🇪🇸 · R. Gran🇺🇸 · I. Ruiz Simo🇪🇸 · F Sanchez🇪🇸 · M. J. Vicente Vacas🇪🇸

   RPA correlations, spectral function and 2p2h (multi-nucleon) effects on charged-current neutrino-nucleus reactions without emitted pions are discussed. We pay attention to the influence of RPA and multi-nucleon mechanisms on the MiniBooNE and MINERvA flux folded differential cross sections, the MiniBooNE flux unfolded total cross section and the neutrino energy reconstruction.

   ↳ hep-phnucl-thNucl.Part.Phys.Proc.(2016)·13 citations
9. 09*

   Understanding Interquark Force and Quark Masses in Perturbative QCD

   Y. Sumino🇯🇵

   This lecture note presents a self-contained introduction to the theory of a heavy quark-antiquark ($Q\bar{Q}$) system in terms of perturbative QCD. The lecture is intended for non-experts, such as graduate course students. The heavy $Q\bar{Q}$ system serves as an ideal laboratory for testing various aspects of QCD: We can examine the nature of renormalons in perturbative series; an effective field theory Potential-NRQCD is constructed, whose derivation from full QCD can be traced stepwise; we see absorption of renormalons by non-perturbative matrix elements in OPE clearly; a systematic short-distance expansion of UV contributions can be performed, which predicts a "Coulomb+linear" potential in perturbative QCD; we can test these theoretical formulations by comparison to lattice computations, where we observe a significant overlap with perturbative regime; finally we can test our microscopic understanding by comparing to experimental data for the bottomonium states. These subjects are covered in a concise and elementary manner. Overall, we provide a microscopic description of the main dynamics of a heavy $Q\bar{Q}$ system, as an example for which theoretical framework, practical computations and qualitative understanding have been most advanced.

   ↳ hep-phnucl-th19 citations
10. 10*

    The muon g-2: Dyson-Schwinger status on hadronic light-by-light scattering

    Gernot Eichmann🇩🇪 · Christian S. Fischer🇩🇪 · Walter Heupel🇩🇪 · Richard Williams🇩🇪

    We give a status report on the hadronic light-by-light scattering contribution to the muon's anomalous magnetic moment from the Dyson-Schwinger approach. We discuss novel, model-independent properties of the light-by-light amplitude: we give its covariant decomposition in view of electromagnetic gauge invariance and Bose symmetry, and we identify the relevant kinematic regions that are probed under the integral. The decomposition of the amplitude at the quark level and the importance of its various diagrams are discussed and related to model approaches.

    ↳ hep-phhep-latnucl-thAIP Conf.Proc.(2016)·35 citations
11. 11*

    Constraints on the chiral unitary $\bar{K}N$ amplitude from $\pi \Sigma K^{+}$ photoproduction data

    Maxim Mai🇩🇪 · Ulf-G. Meißner🇩🇪

    A chiral unitary approach for antikaon-nucleon scattering in on-shell factorization is studied. We find multiple sets of parameters for which the model describes all existing hadronic data similarly well. We confirm the two-pole structure of the $\Lambda (1405)$. The narrow $\Lambda (1405)$ pole appears at comparable positions in the complex energy plane, whereas the location of the broad pole suffers from a large uncertainty. In the second step, we use a simple model for photoproduction of $K^{+}\pi \Sigma$ off the proton and confront it with the experimental data from the CLAS collaboration. It is found that only a few of the hadronic solutions allow for a consistent description of the CLAS data within the assumed reaction mechanism.

    ↳ hep-phhep-exnucl-exnucl-thEPJA(2015)·208 citations
12. 12*

    Observation of the critical end point in the phase diagram for hot and dense nuclear matter

    Roy A. Lacey (Depts. of Chemistry and Physics, Stony Brook University)🇺🇸

    Excitation functions for the Gaussian emission source radii difference ($R_{\text{out}}^2-R_{\text{side}}^2$) obtained from two-pion interferometry measurements in Au+Au ($\sqrt{s_{NN}}=7.7-200$ GeV) and Pb+Pb ($\sqrt{s_{NN}}=2.76$ TeV) collisions, are studied for a broad range of collision centralities. The observed non-monotonic excitation functions validate the finite-size scaling patterns expected for the deconfinement phase transition and the critical end point (CEP), in the temperature vs. baryon chemical potential ($T,{\mu }_B$) plane of the nuclear matter phase diagram. A Finite-Size Scaling (FSS) analysis of these data indicate a second order phase transition with the estimates $T^{\text{cep}}\sim 165$~MeV and ${\mu }_B^{\text{cep}}\sim 95$~MeV for the location of the critical end point. The critical exponents ($\nu \sim 0.66$ and $\gamma \sim 1.2$) extracted via the same FSS analysis, places the CEP in the 3D Ising model universality class.

    ↳ nucl-exnucl-thPRL(2015)·122 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.