Nuclear Theory·nucl-th

Thursday·October 6, 2016

10 papers—5 primary·5 cross-listed

01
[Submitted on 4 Oct 2016]
Manifestation of the $P$ -wave diproton resonance in single-pion production in $pp$ collisions
M. N. Platonova🇷🇺 · V. I. Kukulin🇷🇺
It is demonstrated that many important features of single-pion production in $pp$ collisions at intermediate energies ( $T_{p} ≃ 400$ - $800$ MeV) can naturally be explained by supposing excitation of intermediate diproton resonances in $pp$ channels $^{1} D_{2}$ , $^{3} F_{3}$ and $^{3} P_{2}$ , in addition to conventional mechanisms involving an intermediate $Δ$ -isobar. We predict for the first time the crucial role of the $^{3} P_{2}$ diproton resonance, found in recent experiments on the single-pion production reaction $pp \to pp (^{1} S_{0}) π^{0}$ , in reproducing the proper behavior of spin-correlation parameters in the reaction $pp \to d π^{+}$ which were poorly described by conventional meson-exchange models to date. The possible quark structure of the $P$ -wave diproton resonances is also discussed.
Comments:
Version accepted for publication in Physical Review D
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1610.01207 [pdf]
PRD(2016)·18 citations
02
[Submitted on 5 Oct 2016]
High-density kaonic-proton matter (KPM) composed of Lambda* equiv K-p multiplets and its astrophysical connections
Yoshinori Akaishi🇯🇵 · Toshimitsu Yamazaki🇯🇵
We propose and examine a new high-density composite of $Λ^{*} \equiv K^{-} p = (s u ˉ) \otimes (uu d)$ , which may be called {\it Kaonic Proton Matter (KPM)}, or simply, {\it $Λ^{*}$ -Matter}, where substantial shrinkage of baryonic bound systems originating from the strong attraction of the $(K ˉ N)^{I = 0}$ interaction takes place, providing a ground-state neutral baryonic system with a huge energy gap. The mass of an ensemble of $(K^{-} p)_{m}$ , where $m$ , the number of the $K^{-} p$ pair, is larger than $m \approx 10$ , is predicted to drop down below its corresponding neutron ensemble, $(n)_{m}$ , since the attractive interaction is further increased by the Heitler-London type molecular covalency, as well as by chiral symmetry restoration of the QCD vacuum. Since the seed clusters ( $K^{-} p$ , $K^{-} pp$ and $K^{-} K^{-} pp$ ) are short-lived, the formation of such a stabilized relic ensemble, $(K^{-} p)_{m}$ , may be conceived during the Big-Bang Quark Gluon Plasma (QGP) period in the early universe before the hadronization and $q u a r k$ - $an t i$ - $q u a r k$ annihilation proceed. At the final stage of baryogenesis a substantial amount of primordial ( $u ˉ, d ˉ$ )'s are transferred and captured into {\it KPM}, where the anti-quarks find places to survive forever. The expected {\it KPM} state may be {\it cold, dense and neutral $q ˉ q$ -hybrid ({\it Quark Gluon Bound (QGB)}) states, $[s (u ˉ \otimes u) u d]_{m}$ ,} to which the relic of the disappearing anti-quarks plays an essential role as hidden components. The {\it KPM} may also be produced during the formation and decay of neutron stars.
Comments:
5 pages, 5 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1610.01249 [pdf]
PLB(2017)·17 citations
03
[Submitted on 5 Oct 2016]
Chiral potential renormalized in harmonic-oscillator space
C.-J. Yang🇫🇷
We renormalize the chiral effective field theory (EFT) potential in harmonic-oscillator (HO) model space. The low energy constants (LECs) are utilized to absorb not just the ultra-violet part of the physics due to the cutoff, but also the infrared part due to the truncation of model space. We use the inverse J-matrix method to reproduce the nucleon-nucleon (NN) scattering phase shifts in the given model space. We demonstrate that by including the NLO correction, the nucleon-nucleon scattering in the continuum could be well reproduced in the truncated HO trap space up to laboratory energy $T_{l ab} = 100$ MeV with number of HO basis $n_{ma x}$ as small as 10. A perturbative power counting starts at subleading order is adopted in this work, and how to extract the perturbative contribution is demonstrated. Our work serves as the input to perform ab-initio calculations.
Comments:
published version. 23 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1610.01350 [pdf]
PRC(2016)·25 citations
04
[Submitted on 4 Oct 2016]
Towards a Unified Model of Neutrino-Nucleus Reactions for Neutrino Oscillation Experiments
S.X. Nakamura (Osaka Univ.)🇯🇵 · H. Kamano (KEK, J-PARC)🇯🇵 · Y. Hayato (ICRR, Univ. of Tokyo)🇯🇵 · M. Hirai (Nippon Inst. Tech.)🇯🇵 · W. Horiuchi (Hokkaido Univ.)🇯🇵 · S. Kumano (KEK, J-PARC)🇯🇵 · T. Murata (Osaka Univ.)🇯🇵 · K. Saito (Tokyo Univ. of Sci.)🇯🇵 · M. Sakuda (Okayama Univ.)🇯🇵 · T. Sato (Osaka Univ., J-PARC)🇯🇵 · Y. Suzuki (Niigata Univ., RIKEN)🇯🇵
A precise description of neutrino-nucleus reactions will play a key role in addressing fundamental questions such as the leptonic CP violation and the neutrino mass hierarchy through analyzing data from next-generation neutrino oscillation experiments. The neutrino energy relevant to the neutrino-nucleus reactions spans a broad range and, accordingly, the dominant reaction mechanism varies across the energy region from quasi-elastic scattering through nucleon resonance excitations to deep inelastic scattering. This corresponds to transitions of the effective degree of freedom for theoretical description from nucleons through meson-baryon to quarks. The main purpose of this review is to report our recent efforts towards a unified description of the neutrino-nucleus reactions over the wide energy range; recent overall progress in the field is also sketched. Starting with an overview of the current status of neutrino-nucleus scattering experiments, we formulate the cross section to be commonly used for the reactions over all the energy regions. A description of the neutrino-nucleon reactions follows and, in particular, a dynamical coupled-channels model for meson productions in and beyond the $Δ$ (1232) region is discussed in detail. We then discuss the neutrino-nucleus reactions, putting emphasis on our theoretical approaches. We start the discussion with electroweak processes in few-nucleon systems studied with the correlated Gaussian method. Then we describe quasi-elastic scattering with nuclear spectral functions, and meson productions with a $Δ$ -hole model. Nuclear modifications of the parton distribution functions determined through a global analysis are also discussed. Finally, we discuss issues to be addressed for future developments.
Comments:
68 pages, 33 figures; (v2) reference added, author name in metadata corrected; (v3) Discussion extended in Sec. I and IV, Fig. 10 added to compare with a previous result on two-pion productions, Table I extended to include a comparison with a recent T2K result on coherent pion production
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1610.01464 [pdf]
Rept.Prog.Phys.(2017)·42 citations
05
[Submitted on 4 Oct 2016]
$D ˉ D$ meson pair production in antiproton-nucleus collisions
R. Shyam🇮🇳 · K. Tsushima🇧🇷
We study the $D ˉ D$ ( $D ˉ^{0} D^{0}$ and $D^{-} D^{+}$ ) charm meson pair production in antiproton ( $p ˉ$ ) induced reactions on nuclei at beam energies ranging from threshold to several GeV. Our model is based on an effective Lagrangian approach that has only the baryon-meson degrees of freedom and involves the physical hadron masses. The reaction proceeds via the $t$ -channel exchanges of $Λ_{c}^{+}$ , $Σ_{c}^{+}$ , and $Σ_{c}^{++}$ baryons in the initial collision of the antiproton with one of the protons of the target nucleus. The medium effects on the exchanged baryons are included by incorporating in the corresponding propagators, the effective charm baryon masses calculated within a quark-meson coupling (QMC) model. The wave functions of the bound proton have been determined within the QMC model as well as in a phenomenological model where they are obtained by solving the Dirac equation with appropriate scalar and vector potentials. The initial- and final-state distortion effects have been approximated by using an eikonal approximation-based procedure. Detailed numerical results are presented for total and double differential cross sections for the $D ˉ^{0} D^{0}$ and $D^{-} D^{+}$ production reactions on $^{16}$ O and $^{90}$ Zr targets. It is noticed that at $p ˉ$ beam momenta of interest to the $P ˉ A N D A$ experiment, medium effects lead to noticeable enhancements in the charm meson production cross sections.
Comments:
23 pages, 8 figures, Journal print version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1610.01473 [pdf]
PRD(2016)·12 citations
06
[Submitted on 5 Oct 2016] (cross-list from hep-lat)
Time evolution of linearized gauge field fluctuations on a real-time lattice
Aleksi Kurkela🇨🇭 · Tuomas Lappi🇫🇮 · Jarkko Peuron🇫🇮
Classical real-time lattice simulations play an important role in understanding non-equilibrium phenomena in gauge theories and are used in particular to model the prethermal evolution of heavy-ion collisions. Due to instabilities, small quantum fluctuations on top of the classical background may significantly affect the dynamics of the system. In this paper we argue for the need for a numerical calculation of a system of classical gauge fields and small linearized fluctuations in a way that keeps the separation between the two manifest. We derive and test an explicit algorithm to solve these equations on the lattice, maintaining gauge invariance and Gauss's law.
Comments:
8 pages, 4 figures, v2: typos corrected, references added
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1610.01355 [pdf]
EPJC(2016)·24 citations
07
[Submitted on 5 Oct 2016] (cross-list from physics.ins-det)
FMEA Based Risk Assessment of Component Failure Modes in Industrial Radiography
Alok Pandey · Meghraj Singh · A. U. Sonawane · Prashant S. Rawat
Industrial radiography has its inimitable role in non-destructive examinations. Industrial radiography devices, consisting of significantly high activity of the radioisotopes, are operated manually by remotely held control unit. Malfunctioning of these devices may cause potential exposure to the operator and nearby public, and thus should be practiced under a systematic risk control. To ensure the radiation safety, proactive risk assessment should be implemented. Risk assessment in industrial radiography using the Failure Modes & Effect Analysis (FMEA) for the design and operation of industrial radiography exposure devices has been carried out in this study. Total 56 component failure modes were identified and Risk Priority Numbers (RPNs) were assigned by the FMEA expert team, based on the field experience and reported failure data of various components. Results shows all the identified failure modes have RPN in the range of 04 to 216 and most of the higher RPN are due to low detectability and high severity levels. Assessment reveals that increasing failure detectability is a practical and feasible approach to reduce the risk in most of the failure modes of industrial radiography devices. Actions for reducing RPN for each failure mode have been suggested. Feasibility of FMEA for risk assessment in industrial radiography has been established by this study
Subjects:
Instrumentation and Detectors (physics.ins-det); Nuclear Theory (nucl-th); physics.med-ph (physics.med-ph)
arXiv:
1610.01364 [pdf]
0 citations
08
[Submitted on 5 Oct 2016] (cross-list from hep-lat)
Pion-nucleon scattering in the Roper channel from lattice QCD
C. B. Lang🇦🇹 · L. Leskovec🇺🇸 · M. Padmanath🇩🇪 · S. Prelovsek🇺🇸
We present a lattice QCD study of $N π$ scattering in the positive-parity nucleon channel, where the puzzling Roper resonance $N^{*} (1440)$ resides in experiment. The study is based on the PACS-CS ensemble of gauge configurations with $N_{f} = 2 + 1$ Wilson-clover dynamical fermions, $m_{π} ≃ 156$ MeV and $L ≃ 2.9$ fm. In addition to a number of $q q q$ interpolating fields, we implement operators for $N π$ in $p$ -wave and $N σ$ in $s$ -wave. In the center-of-momentum frame we find three eigenstates below 1.65 GeV. They are dominated by $N (0)$ , $N (0) π (0) π (0)$ (mixed with $N (0) σ (0)$ ) and $N (p) π (- p)$ with $p ≃ 2 π / L$ , where momenta are given in parentheses. This is the first simulation where the expected multi-hadron states are found in this channel. The experimental $N π$ phase-shift would -- in the approximation of purely elastic $N π$ scattering -- imply an additional eigenstate near the Roper mass $m_{R} ≃ 1.43$ GeV for our lattice size. We do not observe any such additional eigenstate, which indicates that $N π$ elastic scattering alone does not render a low-lying Roper. Coupling with other channels, most notably with $N π π$ , seems to be important for generating the Roper resonance, reinforcing the notion that this state could be a dynamically generated resonance. Our results are in line with most of previous lattice studies based just on $q q q$ interpolators, that did not find a Roper eigenstate below $1.65$ GeV. The study of the coupled-channel scattering including a three-particle decay $N π π$ remains a challenge.
Comments:
14 pages, 9 figures, version published in Phys. Rev. D plus additional footnote and reference
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1610.01422 [pdf]
PRD(2017)·128 citations
09
[Submitted on 5 Oct 2016] (cross-list from hep-th)
Critical behavior of non-hydrodynamic quasinormal modes in a strongly coupled plasma
Stefano I. Finazzo (Sao Paulo, IFT)🇧🇷 · Romulo Rougemont (Sao Paulo U.)🇧🇷 · Maicon Zaniboni (Sao Paulo U.)🇧🇷 · Renato Critelli (Sao Paulo U.)🇧🇷 · Jorge Noronha (Sao Paulo U.)🇧🇷
We study the behavior of quasinormal modes in a top-down holographic dual corresponding to a strongly coupled $N = 4$ super Yang-Mills plasma charged under a $U (1)$ subgroup of the global $S U (4)$ R-symmetry. In particular, we analyze the spectra of quasinormal modes in the external scalar and vector diffusion channels near the critical point and obtain the behavior of the characteristic equilibration times of the plasma as the system evolves towards the critical point of its phase diagram. Except close to the critical point, we observe that by increasing the chemical potential one generally increases the damping rate of the quasinormal modes, which leads to a reduction of the characteristic equilibration times in the dual strongly coupled plasma. However, as one approaches the critical point the typical equilibration time (as estimated from the lowest non-hydrodynamic quasinormal mode frequency) increases, although remaining finite, while its derivative with respect to the chemical potential diverges with exponent -1/2. We also find a purely imaginary non-hydrodynamical mode in the vector diffusion channel at nonzero chemical potential which dictates the equilibration time in this channel near the critical point.
Comments:
31 pages, 15 figures, version accepted for publication in JHEP
Subjects:
High Energy Physics — Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
1610.01519 [pdf]
JHEP(2017)·46 citations
10
[Submitted on 5 Oct 2016] (cross-list from nucl-ex)
Unexpected distribution of $ν 1 f_{7/2}$ strength in the calcium isotopes at $N$ =30
H. L. Crawford🇺🇸 · A. O. Macchiavelli🇺🇸 · P. Fallon🇺🇸 · M. Albers🇺🇸 · V. M. Bader🇺🇸 · D. Bazin🇺🇸 · C. M. Campbell🇺🇸 · R. M. Clark🇺🇸 · M. Cromaz🇺🇸 · J. Dilling🇨🇦 · A. Gade🇺🇸 · A. T. Gallant🇨🇦 and 21 other authors
The calcium isotopes have emerged as an important testing ground for new microscopically derived shell-model interactions, and a great deal of focus has been directed toward this region. We investigate the relative spectroscopic strengths associated with $1 f_{7/2}$ neutron hole states in $^{47, 49}$ Ca following one-neutron knockout reactions from $^{48, 50}$ Ca. The observed reduction of strength populating the lowest 7/2 $_{1}^{-}$ state in $^{49}$ Ca, as compared to $^{47}$ Ca, is consistent with the description given by shell-model calculations based on two- and three-nucleon forces in the neutron $p f$ model space, implying a fragmentation of the $l$ =3 strength to higher-lying states. The experimental result is inconsistent with both the GXPF1 interaction routinely used in this region of the nuclear chart and with microscopic calculations in an extended model space including the $ν 1 g_{9/2}$ orbital.
Comments:
6 pages, 2 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1610.01575 [pdf]
PRC(2017)·18 citations

Affiliations

first authorsco-authorsvia INSPIRE