Nuclear Theory·nucl-th

Monday·December 31, 2018

14 papers—4 primary·10 cross-listed

05
[Submitted on 20 Dec 2018] (cross-list from hep-ph)
Modified combinant analysis of the $e^{+} e^{-}$ multiplicity distributions
H.W.Ang🇸🇬 · M.Ghaffar🇸🇬 · A.H.Chan🇸🇬 · M.Rybczyński🇵🇱 · G.Wilk🇵🇱 · Z.Włodarczyk🇵🇱
As shown recently, one can obtain additional information from the measured multiplicity distributions, $P (N)$ , by extracting the so-called modified combinants, $C_{j}$ . This information is encoded in their specific oscillatory behavior, which can be described only by some combinations of compound distributions, the basic part of which is the Binomial Distribution. So far this idea was applied to $pp$ and $p p ˉ$ processes; in this note we show that an even stronger effect is observed in the $C_{j}$ deduced from $e^{+} e^{-}$ collisions. We present its possible explanation in terms of the so called Generalised Multiplicity Distribution (GMD) proposed some time ago.
Comments:
Revised version, accepted for publication in Modern Physics Letters A
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1812.08840 [pdf]
Mod.Phys.Lett.A(2019)·6 citations
06
[Submitted on 27 Dec 2018] (cross-list from physics.comp-ph)
A Data-driven Framework for Error Estimation and Mesh-Model Optimization in System-level Thermal-Hydraulic Simulation
Han Bao · Nam Dinh · Jeffrey Lane · Robert Youngblood
Over the past decades, several computer codes were developed for simulation and analysis of thermal-hydraulics of system behaviors in nuclear reactors under operating, abnormal transient and accident conditions. However, simulation errors and uncertainties still inevitably exist even while these codes have been extensively assessed and used. In this work, a data-driven framework (Optimal Mesh/Model Information System, OMIS) is formulated and demonstrated to estimate simulation error and suggest optimal selection of coarse mesh size and models for low-fidelity system-level thermal-hydraulic simulation, such as coarse-mesh Computational Fluid Dynamics-like (CFD-like) codes, to achieve accuracy comparable to that of high-fidelity simulation, such as high-resolution CFD. Based on high-fidelity data and massive fast-running low-fidelity simulations, error database is built and used to train a machine learning model and find the relationship between local simulation error and local physical features. This machine learning model is then used to generate insight and help correct low-fidelity simulations for similar physical conditions. The OMIS framework is designed as a modularized six-step procedure and accomplished with methods and algorithms in the state of the art. A mixed convection case study was performed to illustrate the entire framework.
Subjects:
Computational Physics (physics.comp-ph); Nuclear Theory (nucl-th)
arXiv:
1812.10581 [pdf]
Nucl.Eng.Des.(2019)·0 citations
07
[Submitted on 27 Dec 2018] (cross-list from hep-ph)
Basics of doubly heavy tetraquarks
A. Valcarce🇪🇸 · J.-M. Richard🇫🇷 · J. Vijande🇪🇸
We outline the most important results regarding the stability of doubly heavy tetraquarks $QQ q ˉ q ˉ$ with an adequate treatment of the four-body dynamics. We consider both color-mixing and spin-dependent effects. Our results are straightforwardly applied to the case of all-heavy tetraquarks $QQ Q ˉ Q ˉ$ . We conclude that the stability is favored in the limit $M_{Q} / m_{q} ≫ 1$ pointing to the stability of the $bb u ˉ d ˉ$ state and the instability of all-heavy tetraquarks.
Comments:
To appear in the Proc. of the Workshop "XIII International Conference on Beauty, Charm and Hyperon Hadrons", Peniche (Portugal), June 17-23, 2018. To be published by IOP Conference Series
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1812.10691 [pdf]
J.Phys.Conf.Ser.(2019)·0 citations
08
[Submitted on 27 Dec 2018] (cross-list from hep-ph)
The Spinless Relativistic Hellmann Problem
Wolfgang Lucha🇦🇹 · Franz F. Schöberl🇦🇹
We compile some easily deducible information on the discrete eigenvalue spectra of spinless Salpeter equations encompassing, besides a relativistic kinetic term, interactions which are expressible as superpositions of an attractive Coulomb potential and an either attractive or repulsive Yukawa potential and, hence, generalizations of the Hellmann potential employed in several areas of science. These insights should provide useful guidelines to all attempts of finding appropriate descriptions of bound states by (semi-) relativistic equations of motion.
Comments:
10 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
1812.10756 [pdf]
Int.J.Mod.Phys.A(2019)·3 citations
09
[Submitted on 27 Dec 2018] (cross-list from astro-ph.HE)
Bayesian Analysis for Extracting Properties of the Nuclear Equation of State from Observational Data including Tidal Deformability from GW170817
A. Ayriyan · D. Alvarez-Castillo · D. Blaschke · H. Grigorian
We develop a Bayesian analysis method for selecting the most probable equation of state under a set of constraints from compact star physics, which now include the tidal deformability from GW170817. We apply this method for the first time to a two-parameter family of hybrid equations of state that is based on realistic models for the hadronic phase (KVORcut02) and the quark matter phase (SFM $α$ ) which produce a third family of hybrid stars in the mass-radius diagram. One parameter ( $α$ ) characterizes the screening of the string tension in the string-flip model of quark matter while the other ( $Δ_{P}$ ) belongs to the mixed phase construction that mimics the thermodynamics of pasta phases and includes the Maxwell construction as a limiting case for $Δ_{P} = 0$ . We present the corresponding results for compact star properties like mass, radius and tidal deformabilities and use empirical data for them in the newly developed Bayesian analysis method to obtain the probabilities for the model parameters within their considered range.
Comments:
8 pages, 4 figures, version accepted for publication in universe
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1812.10796 [pdf]
Universe(2019)·23 citations
10
[Submitted on 28 Dec 2018] (cross-list from hep-ph)
Casimir effect for nucleon parity doublets
Tsutomu Ishikawa🇯🇵 · Katsumasa Nakayama🇯🇵 · Kei Suzuki🇯🇵
Finite-volume effects for the nucleon chiral partners are studied within the framework of the parity-doublet model. Our model includes the vacuum energy shift for nucleons, which is the Casimir effect. We find that for the antiperiodic boundary the finite-volume effect leads to chiral symmetry restoration, and the masses of the nucleon parity doublets degenerate. For the periodic boundary, the chiral symmetry breaking is enhanced, and the masses of the nucleons also increase. We also discuss the finite-temperature effect and the dependence on the number of compactified spatial dimensions.
Comments:
14 pages, 11 figures, 3 tables; published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1812.10964 [pdf]
PRD(2019)·23 citations
11
[Submitted on 28 Dec 2018] (cross-list from hep-lat)
QED-corrected Lellouch-Lüscher formula for $K \to π π$ decay
Yiming Cai🇺🇸 · Zohreh Davoudi🇯🇵
A precise SM prediction for the direct CP violation in the $K \to π π$ decay process is of great importance in confronting experiments and constraining new physics. The state-of-art lattice QCD study of this process will soon achieve a precision that QED effects can no longer be neglected. The inclusion of QED in such calculations is planned, and the formalism to relate the finite-volume matrix element obtained from these calculations to the physical amplitude is underway. Here, we report on the progress towards an extension of the Lellouch-Lüscher formalism in presence of QED, with the goal of enabling the extraction of physical amplitudes for the $K \to π π$ process with charged initial and/or final states.
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1812.11015 [pdf]
PoS(2018)·15 citations
12
[Submitted on 28 Dec 2018] (cross-list from hep-ph)
Gluon emission from heavy quarks in dense nuclear matter
Le Zhang🇨🇳 · De-Fu Hou🇨🇳 · Guang-You Qin🇨🇳
We study the medium-induced gluon emission process experienced by a hard jet parton propagating through the dense nuclear matter in the framework of deep inelastic scattering off a large nucleus. We work beyond the collinear rescattering expansion and the soft gluon emission limit, and derive a closed formula for the medium-induced single gluon emission spectrum from a heavy or light quark jet interacting with the dense nuclear medium via transverse and longitudinal scatterings. Without performing the collinear rescattering expansion, the medium-induced gluon emission spectrum is controlled by the full distribution of the differential elastic scattering rates between the propagating partons and the medium constituents. We further show that if one utilizes heavy static scattering centers for the traversed nuclear matter and takes the soft gluon emission limit, our result can reduce to the first order in opacity Djordjevic-Gyulassy-Levai-Vitev formula.
Comments:
21 pages, 14 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1812.11048 [pdf]
PRC(2019)·18 citations
13
[Submitted on 23 Dec 2018] (cross-list from hep-ph)
Testing of quasi-elastic neutrino charged-current and two-body meson exchange current models with the MiniBooNE neutrino data and analysis of these processes at energies available at the NOvA experiment
A.V. Butkevich · S.V. Luchuk
The charged-current quasi-elastic (CCQE) scattering of muon neutrinos on a carbon target is analyzed using the relativistic distorted-wave impulse approximation (RDWIA) taking into account the contribution of the two-particle and two-hole meson exchange current ( $2 p - 2 h$ MEC) to the weak response functions. A fit the RDWIA+MEC model to the MiniBooNE neutrino data is performed and the best fit value of nucleon axial mass $M_{A} = 1.2 \pm 0.06$ GeV is obtained. We also extract the values of the axial form factor $F_{A} (Q^{2})$ as a function of the squared momentum transfer $Q^{2}$ from the measured $d σ / d Q^{2}$ cross section. The flux-integrated CCQE-like differential cross sections for neutrino scattering at energies of the NOvA experiment are estimated within the RDWIA+MEC approach.
Comments:
33 pages, 19 figures. arXiv admin note: text overlap with arXiv:1708.04052
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1812.11073 [pdf]
PRD(2019)·14 citations
14
[Submitted on 28 Dec 2018] (cross-list from hep-lat)
Symmetries and Interactions from Lattice QCD
A. Nicholson🇺🇸 · E. Berkowitz🇩🇪 · H. Monge-Camacho🇺🇸 · D. Brantley🇺🇸 · N. Garron🇬🇧 · C.C. Chang🇯🇵 · E. Rinaldi🇺🇸 · C. Monahan🇺🇸 · C. Bouchard🇬🇧 · M.A. Clark🇺🇸 · B. Joo🇺🇸 · T. Kurth🇺🇸 and 3 other authors
Precision experimental tests of the Standard Model of particle physics (SM) are one of our best hopes for discovering what new physics lies beyond the SM (BSM). Key in the search for new physics is the connection between theory and experiment. Forging this connection for searches involving low-energy hadronic or nuclear environments requires the use of a non-perturbative theoretical tool, lattice QCD. We present two recent lattice QCD calculations by the CalLat collaboration relevant for new physics searches: the nucleon axial coupling, $g_{A}$ , whose precise value as predicted by the SM could help point to new physics contributions to the so-called "neutron lifetime puzzle", and hadronic matrix elements of short-ranged operators relevant for neutrinoless double beta decay searches.
Comments:
Plenary talk presented CIPANP2018. 11 pages, 3 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1812.11127 [pdf]
2 citations

Affiliations

first authorsco-authorsvia INSPIRE