Nuclear Theory·nucl-th

Tuesday·November 17, 2015

16 papers—7 primary·9 cross-listed

08
D meson mass increase by restoration of chiral symmetry in nuclear matter
Kei Suzuki🇯🇵 · Philipp Gubler🇮🇹 · Makoto Oka🇯🇵
Spectral functions of the pseudoscalar $D$ meson in the nuclear medium are analyzed using QCD sum rules and the maximum entropy method. This approach enables us to extract the spectral functions without any phenomenological assumption, and thus to visualize in-medium modification of the spectral functions directly. It is found that the reduction of the chiral condensates of dimension 3 and 5 causes the masses of both $D^{+}$ and $D^{-}$ mesons to grow gradually at finite density. Additionally, we construct charge-conjugate-projected sum rules and find a $D^{+}$ - $D^{-}$ mass splitting of about -15 MeV at nuclear saturation density.
↳ hep-phnucl-thPRC(2016)·55 citations
09
Nucleon axial and tensor charges with dynamical overlap quarks
N. Yamanaka🇯🇵 · H. Ohki🇺🇸 · S. Hashimoto🇯🇵 · T. Kaneko🇯🇵
We report on our calculation of the nucleon axial and tensor charges in 2+1-flavor QCD with dynamical overlap quarks. Gauge ensembles are generated at a single lattice spacing 0.12 fm and at a strange quark mass close to its physical value. We employ the all-mode-averaging technique to calculate the relevant nucleon correlation functions, and the disconnected quark loop is efficiently calculated by using the all-to-all quark propagator. We present our preliminary results for the isoscalar and isovector charges obtained at pion masses $m_{π}$ = 450 and 540 MeV.
↳ hep-lathep-phnucl-thPoS(2016)·11 citations
10
Mesoscopic dynamics of fermionic cold atoms ---Quantitative analysis of transport coefficients and relaxation times---
Yuta Kikuchi · Kyosuke Tsumura · Teiji Kunihiro
We give a quantitative analysis of the dynamical properties of fermionic cold atomic gases in normal phase, such as the shear viscosity, heat conductivity, and viscous relaxation times, using the novel microscopic expressions derived by the renormalization group (RG) method, where the Boltzmann equation is faithfully solved to extract the hydrodynamics without recourse to any ansatz. In particular, we examine the quantum statistical effects, temperature dependence, and scattering-length dependence of the transport coefficients and the viscous relaxation times. The numerical calculation shows that the relation $τ_{π} = η / P$ , which is derived in the relaxation-time approximation (RTA) and is used in most of the literature, turns out to be satisfied quite well, while the similar relation for the viscous relaxation time $τ_{J}$ of the heat conductivity is satisfied only approximately with a considerable error.
↳ cond-mat.quant-gasnucl-thphysics.flu-dynPLA(2016)·16 citations
11
Strong decay patterns of the hidden-charm pentaquark states $P_{c} (4380)$ and $P_{c} (4450)$
Guang-Juan Wang🇨🇳 · Li Ma🇨🇳 · Xiang Liu🇨🇳 · Shi-Lin Zhu🇨🇳
With the heavy quark symmetry and spin rearrangement scheme, we study the strong decay behavior of the hidden-charm pentaquark states with $J^{P} = \frac{3}{2}^{\pm}, \frac{5}{2}^{\pm}$ assuming they are molecular candidates composed of $D ˉ^{(*)}$ and $Σ_{c}^{(*)}$ . We obtain several typical ratios of the partial decay widths of the hidden-charm pentaquarks. For the three S-wave $(D ˉ Σ_{c}^{*})$ , $(D ˉ^{*} Σ_{c})$ and $(D ˉ^{*} Σ_{c}^{*})$ molecular pentaquarks with $J^{P} = 3 / 2^{-}$ , we have obtained the ratio of their $J / ψ N$ decay widths: $Γ [(D ˉ Σ_{c}^{*})] : Γ [(D ˉ^{*} Σ_{c})] : Γ [(D ˉ^{*} Σ_{c}^{*})] = 2.7 : 1.0 : 5.4$ , which may be useful to further test the possible molecular assignment of the $P_{c}$ states.
↳ hep-phhep-exhep-latnucl-thPRD(2016)·32 citations
12
Nuclear physics from QCD on lattice
Takashi Inoue · for HAL QCD Collaboration
We have presented a strategy to study nuclei and nuclear matters from first principles, namely, from QCD. We first compute nucleon-nucleon potentials numerically in lattice QCD, and then use them to investigate properties of nuclei and nuclear matter by various methods developed in nuclear physics. As a demonstration that this strategy works, mass and structure of ^4^He, ^16^O and ^40^Ca, and equation of state of nuclear matters are determined with the lattice QCD induced two-nucleon potentials in a heavy quark region as an input. We have found that these nuclei and the symmetric nuclear matter are bound at one quark mass corresponding to the pseudo-scalar meson (pion) mass of 469 MeV (the octet baryon (nucleon) mass of 1161 MeV). The obtained binding energy per nucleon has a uniform mass-number A dependence which is consistent to the Bethe-Weizsacker mass formula qualitatively. The present study demonstrates that our strategy works well to investigate various properties of atomic nuclei and nuclear matter starting from QCD, without depending on models or experimental information about the nuclear force.
↳ hep-lathep-phnucl-exnucl-thPoS(2016)·6 citations
13
Decay $B \to K^{*} (\to K π) ℓ^{+} ℓ^{-}$ in covariant quark model
Stanislav Dubnička🇸🇰 · Anna Z. Dubničková🇸🇰 · Nurgul Habyl🇰🇿 · Mikhail A. Ivanov🇷🇺 · Andrej Liptaj🇸🇰 · Guliya S. Nurbakova🇰🇿
Our article is devoted to the study of the rare $B \to K^{*} ℓ^{+} ℓ^{-}$ ~decay where $ℓ = e, μ, τ$ . We compute the relevant form factors in the framework of the covariant quark model with infrared confinement in the full kinematical momentum transfer region. The calculated form factors are used to evaluate branching fractions and polarization observables in the cascade decay $B \to K^{*} (\to K π) ℓ^{+} ℓ^{-}$ . We compare the obtained results with available experimental data and the results from other theoretical approaches.
↳ hep-phhep-exnucl-thFew Body Syst.(2016)·15 citations
14
Current algebra for a generalized two-site Bose-Hubbard model
Gilberto N. Santos Filho
We present a current algebra for a generalized two-site Bose-Hubbard model and use it to get the quantum dynamics of the currents. For different choices of the Hamiltonian parameters we get different currents dynamics. We generalize the Heisenberg equation of motion to write the n-th time derivative of any operator.
↳ cond-mat.quant-gascond-mat.mes-hallcond-mat.supr-connucl-th+12 citations
15
A Three-Flavor Chiral Effective Model with Four Baryonic Multiplets within the Mirror Assignment
Lisa Olbrich🇩🇪 · Miklós Zétényi🇩🇪 · Francesco Giacosa🇩🇪 · Dirk H. Rischke🇩🇪
In the case of three quark flavors, (pseudo)scalar diquarks transform as antiquarks under chiral transformations. We construct four spin-1/2 baryonic multiplets from left- and right-handed quarks as well as left- and right-handed diquarks. The fact that two of these multiplets transform in a "mirror" way allows for chirally invariant mass terms. We then embed these baryonic multiplets into the Lagrangian of the so-called extended Linear Sigma Model, which features (pseudo)scalar and (axial-)vector mesons, as well as glueballs. Reducing the Lagrangian to the two-flavor case, we obtain four doublets of nucleonic states. These mix to produce four experimentally observed states with definite parity: the positive-parity nucleon $N (939)$ and Roper resonance $N (1440)$ , as well as the negative-parity resonances $N (1535)$ and $N (1650)$ . We determine the parameters of the nucleonic part of the Lagrangian from a fit to masses and decay properties of the aforementioned states. Studying the limit of vanishing quark condensate, we conclude that $N (939)$ and $N (1535)$ , as well as $N (1440)$ and $N (1650)$ form pairs of chiral partners.
↳ hep-phnucl-thPRD(2016)·37 citations
16
Diffusion Monte Carlo study of strongly interacting two-dimensional Fermi gases
Alexander Galea · Hillary Dawkins · Stefano Gandolfi · Alexandros Gezerlis
Ultracold atomic Fermi gases have been a popular topic of research, with attention being paid recently to two-dimensional (2D) gases. In this work, we perform T=0 ab initio diffusion Monte Carlo calculations for a strongly interacting two-component Fermi gas confined to two dimensions. We first go over finite-size systems and the connection to the thermodynamic limit. After that, we illustrate pertinent 2D scattering physics and properties of the wave function. We then show energy results for the strong-coupling crossover, in between the Bose-Einstein Condensation (BEC) and Bardeen-Cooper-Schrieffer (BCS) regimes. Our energy results for the BEC-BCS crossover are parametrized to produce an equation of state, which is used to determine Tan's contact. We carry out a detailed comparison with other microscopic results. Finally, we calculate the pairing gap for a range of interaction strengths in the strong coupling regime, following from variationally optimized many-body wave functions.
↳ cond-mat.quant-gasnucl-thPRA(2016)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE