Nuclear Theory·nucl-th

Tuesday·October 27, 2015

17 papers—9 primary·8 cross-listed

01
Nuclear Chiral EFT in the Precision Era
Evgeny Epelbaum🇩🇪
Chiral effective field theory has established itself as the method of choice to study nuclear forces and low-energy nuclear dynamics. I review the status and prospects of this approach and discuss ongoing efforts to advance the precision frontier for ab initio description of few-nucleon systems. Special emphasis is put on the precise determination of the two-nucleon force at fifth order in the chiral expansion, role of the chiral symmetry, the convergence pattern of the chiral expansion and the quantification of the theoretical uncertainties. The discussed topics are essential for ongoing studies towards elucidating the structure of the three-nucleon force which will be briefly addressed as well.
nucl-thhep-phnucl-exPoS(2016)·16 citations
02
Nuclear electric dipole moment of light nuclei in the gaussian expansion method
Nodoka Yamanaka🇯🇵 · Emiko Hiyama🇯🇵
The nuclear electric dipole moment is a very sensitive probe of CP violation beyond the standard model, and for light nuclei, it can be evaluated accurately using few-body calculational methods. In this talk, we present the deuteron, $^{3}$ He, $^{3}$ H, $^{6}$ Li, and $^{9}$ Be electric dipole moments calculated using the Gaussian expansion method with a realistic nuclear force, and assuming the one-meson exchange model for the P, CP-odd nuclear force. We then give future prospects for models beyond the standard model such as the supersymmetry.
nucl-thhep-phPoS(2016)·0 citations
03
Interaction of antiprotons with nuclei
J. Hrtánková🇨🇿 · J. Mareš🇨🇿
We performed fully self-consistent calculations of $p ˉ$ -nuclear bound states using a complex $p ˉ$ -nucleus potential accounting for $p ˉ$ -atom data. While the real part of the potential is constructed within the relativistic mean-field (RMF) model, the $p ˉ$ annihilation in the nuclear medium is described by a phenomenological optical potential. We confirm large polarization effects of the nuclear core caused by the presence of the antiproton. The $p ˉ$ annihilation is treated dynamically, taking into account explicitly the reduced phase space for annihilation from deeply bound states as well as the compressed nuclear density due to the antiproton. The energy available for the products of $p ˉ$ annihilation in the nuclear medium is evaluated self-consistently, considering the additional energy shift due to transformation from the $p ˉ N$ system to $p ˉ$ -nucleus system. Corresponding $p ˉ$ widths in the medium are significantly suppressed, however, they still remain considerable for the $p ˉ$ potential consistent with experimental data.
nucl-thNPA(2016)·15 citations
04
Baryon resonances in the strangeness production
Ju-Jun Xie🇨🇳 · En Wang🇨🇳 · Jia-Jun Wu🇦🇺
We have studied the $N^{*} (2120)$ , $Δ^{*} (1940)$ , and the possible $Σ^{*} (1380)$ resonances in the $γ p \to K^{+} Λ (1520)$ , $pp \to n K^{+} Σ (1385)$ , and $Λ p \to Λ p π^{0}$ reactions within the resonance model and the effective Lagrangian approach. It is shown that when the contributions from these baryonic states were considered, the current experimental measurement could be well reproduced. In addition, we also demonstrate that the angular distributions provide direct information of these reactions, which could be useful for the investigation of those states and may be tested by future experiments.
nucl-thhep-phnucl-exJPS Conf.Proc.(2016)·0 citations
05
The $Ξ^{*} K ˉ$ and $Ω η$ interaction within a chiral unitary approach
Siqi Xu🇨🇳 · Ju-Jun Xie🇨🇳 · Xurong Chen🇨🇳 · Duojie Jia🇨🇳
In this work we study the interaction of the coupled channels $Ω η$ and $Ξ^{*} K ˉ$ within the chiral unitary approach. The systems under consideration have total isospins $0$ , strangeness $S = - 3$ , and spin $3/2$ . We studied the $s$ wave interaction which implies that the possible resonances generated in the system can have spin-parity $J^{P} = 3/ 2^{-}$ . The unitary amplitudes in coupled channels develop poles that can be associated with some known baryonic resonances. We find there is a dynamically generated $3/ 2^{-}$ $Ω$ state with mass around $1800$ MeV, which is in agreement with the predictions of the five-quark model.
nucl-thhep-exhep-phnucl-exCommun.Theor.Phys.(2016)·18 citations
06
Nuclear saturation in lowest-order Brueckner theory with two- and three-nucleon forces in view of chiral effective field theory
M. Kohno
The nuclear saturation mechanism is discussed in terms of two-nucleon and three-nucleon interactions in chiral effective field theory (Ch-EFT), using the framework of lowest-order Brueckner theory. After the Coester band, which is observed in calculating saturation points with various nucleon-nucleon (NN) forces, is revisited using modern NN potentials and their low-momentum equivalent interactions, detailed account of the saturation curve of the Ch-EFT interaction is presented. The three-nucleon force (3NF) is treated by reducing it to an effective two-body interaction by folding the third nucleon degrees of freedom. Uncertainties due to the choice of the 3NF low-energy constants $c_{D}$ and $c_{E}$ are discussed. The reduction of the cutoff-energy dependence of the NN potential is explained by demonstrating the effect of the 3NF in the $^{1}$ S $_{0}$ and $^{3}$ S $_{1}$ states.
nucl-thPTEP(2015)·10 citations
07
Heavy-flavor dynamics in relativistic p-Pb collisions at $S_{N N} = 5.02$ TeV
Yingru Xu🇺🇸 · Shanshan Cao🇺🇸 · Marlene Nahrgang🇨🇳 · Weiyao Ke🇺🇸 · Guang-You Qin🇺🇸 · Jussi Auvinen🇺🇸 · Steffen A. Bass🇺🇸
We investigate the heavy flavor dynamics in the quark-gluon plasma (QGP) medium created in p-Pb collisions at the CERN Large Hadron Collider (LHC). In the (3+1)-dimensional viscous hydrodynamics model describing QGP medium, the dynamics of heavy quarks are studied in an improved Langevin framework incorporating both collisional and radiative energy loss. The hadronization of the heavy quarks is given by a hybrid model of fragmentation and recombination. We find that the in-medium evolution of charm quarks raises the D-meson $R_{pP b}$ at low transverse momenta while it suppresses the D-meson $R_{pP b}$ at intermediate momenta. In addition, the elliptic flow of D-meson is calculated. For a diffusion coefficient which reproduces central $R_{AA}$ data at the LHC, we find a much smaller D-meson $v_{2}$ compared to the light hadrons. This observation indicates an incomplete coupling between heavy quarks with the medium, due to the reduced medium size compared to AA collisions.
nucl-thnucl-exNucl.Part.Phys.Proc.(2016)·40 citations
08
Axial-vector dominance predictions in quasielastic neutrino-nucleus scattering
J.E. Amaro🇪🇸 · E. Ruiz Arriola🇪🇸
The axial form factor plays a crucial role in quasielastic neutrino-nucleus scattering, but the error of the theoretical cross section due to uncertainties of $G_{A}$ remains to be established. Reversely, the extraction of $G_{A}$ from the neutrino nucleus cross section suffers from large systematic errors due to nuclear model dependencies, while the use of single parameter dipole fits underestimates the errors and prevents an identification of the relevant kinematics for this determination. We propose to use a generalized axial-vector-meson-dominance (AVMD) in conjunction with large- $N_{c}$ and high energy QCD constrains to model the nucleon axial form factor, as well as the half width rule as an a priori uncertainty estimate. The minimal hadronic ansatz comprises the sum of two monopoles corresponding to the lightest axial-vector mesons being coupled to the axial current. The parameters of the resulting axial form factor are the masses and widths of the two axial mesons as obtained from the averaged PDG values. By applying the half width rule in a Monte Carlo simulation, a distribution of theoretical predictions can then be generated for the neutrino-nucleus quasielastic cross section. We test the model by applying it to the $(ν_{μ}, μ)$ quasielastic cross section from $^{12}$ C for the kinematics of the MiniBooNE experiment. The resulting predictions have no free parameters. We find that the relativistic Fermi gas model globally reproduces the experimental data, giving $χ^{2} /# bin s = 0.81$ . A $Q^{2}$ -dependent error analysis of the neutrino data shows that the uncertainties in the axial form factor $G_{A} (Q^{2})$ are comparable to the ones induced by the a priori half width rule. We identify the most sensitive region to be in the range $0.2 ≲ Q^{2} ≲ 0.6 GeV^{2}$ .
nucl-thhep-phPRD(2016)·32 citations
09
Large-N(c) limit reduces the number of independent few-body parity-violating low-energy constants in pionless effective field theory
Matthias R. Schindler🇺🇸 · Roxanne P. Springer🇺🇸 · Jared Vanasse🇺🇸
The symmetries of the Standard Model dictate that for very low energies, where nucleon dynamics can be described in terms of a pionless effective field theory, the leading-order parity-violating nucleon-nucleon Lagrangian contains five independent unknown low-energy constants (LECs). We find that imposing the approximate symmetry of QCD that appears when the number of colors N(c) becomes large reduces the number of independent LECs to two at leading order in the combined pionless effective field theory and large-N(c) expansions. We also find a relation between the two isoscalar LECs in the large-N(c) limit. This has important implications for the number of experiments and/or lattice calculations necessary to confirm this description of physics.
nucl-thhep-phPRC(2016)·43 citations

Affiliations

first authorsco-authorsvia INSPIRE