Nuclear Theory·nucl-th

Tuesday·October 6, 2015

20 papers—8 primary·12 cross-listed

09
[Submitted on 2 Oct 2015] (cross-list from hep-ph)
From controversy to precision on the sigma meson: a review on the status of the non-ordinary $f_{0} (500)$ resonance
J.R. Pelaez (universidad Complutense de Madrid)🇪🇸
The existence and properties of the sigma meson have been controversial for almost six decades, despite playing a central role in the spontaneous chiral symmetry of QCD or in the nucleon-nucleon attraction. This controversy has also been fed by the strong indications that it is not an ordinary quark-antiquark meson. Here we review both the recent and old experimental data and the model independent dispersive formalisms which have provided precise determinations of its mass and width, finally settling the controversy and leading to its new name: $f_{0} (500)$ . We then provide a rather conservative average of the most recent and advanced dispersive determinations of its pole position $s_{σ} = 44 9_{- 16}^{+ 22} - i (275 \pm 12)$ . In addition, after comprehensive introductions, we will review within the modern perspective of effective theories and dispersion theory, its relation to chiral symmetry, unitarization techniques, its quark mass dependence, popular models, as well as the recent strong evidence, obtained from the QCD $1/ N_{c}$ expansion or Regge theory, for its non ordinary nature in terms of quarks and gluons.
Comments:
170 pages, 39 figures. Final version to appear in Physics Reports. Improved discussions in several sections. New subsection on the sigma and conformal symmetry. Typos corrected and references added
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1510.00653 [pdf]
Phys.Rept.(2016)·499 citations
10
[Submitted on 2 Oct 2015] (cross-list from hep-ph)
Direct and indirect constraints on CP-violating Higgs-quark and Higgs-gluon interactions
Y.-T. Chien🇺🇸 · V. Cirigliano🇺🇸 · W. Dekens🇳🇱 · J. de Vries🇩🇪 · E. Mereghetti🇺🇸
We investigate direct and indirect constraints on the complete set of anomalous CP-violating Higgs couplings to quarks and gluons originating from dimension-6 operators, by studying their signatures at the LHC and in electric dipole moments (EDMs). We show that existing uncertainties in hadronic and nuclear matrix elements have a significant impact on the interpretation of EDM experiments, and we quantify the improvements needed to fully exploit the power of EDM searches. Currently, the best bounds on the anomalous CP-violating Higgs interactions come from a combination of EDM measurements and the data from LHC Run 1. We argue that Higgs production cross section and branching ratios measurements at the LHC Run 2 will not improve the constraints significantly. On the other hand, the bounds on the couplings scale roughly linearly with EDM limits, so that future theoretical and experimental EDM developments can have a major impact in pinning down interactions of the Higgs.
Comments:
Included analysis of Higgs decay processes. References added
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1510.00725 [pdf]
JHEP(2016)·122 citations
11
[Submitted on 2 Oct 2015] (cross-list from nucl-ex)
Modifications of Nucleons in Nuclei
Sebastian E. Kuhn🇺🇸
I summarize recent results and discuss upcoming and planned experiments that attempt to elucidate how the structure of nucleons might be modified by nuclear binding.
Comments:
Conference Proceedings CIPANP2015
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1510.00737 [pdf]
1 citation
12
[Submitted on 2 Oct 2015] (cross-list from hep-ph)
Uncovering the Matter-Neutrino Resonance
D. Vaananen🇺🇸 · G. C. McLaughlin🇺🇸
Matter Neutrino Resonances (MNRs) can drastically modify neutrino flavor evolution in astrophysical environments and may significantly impact nucleosynthesis. Here we further investigate the underlying physics of MNR type flavor transitions. We provide generalized resonance conditions and make analytical predictions for the behavior of the system. We discuss the adiabatic evolution of these transitions, considering both Symmetric and Standard scenarios. Symmetric MNR transitions differ from Standard MNR transitions in that both neutrinos and antineutrinos can completely transform to other flavors simultaneously. We provide an example of the simplest system in which such transitions can occur with a neutrino and an antineutrino having a single energy and emission angle. We further apply linearized stability analysis to predict the location of self-induced nutation type (or bipolar) oscillations due to neutrino-neutrino interactions in the regions where MNR is ineffective. In all cases, we compare our analytical predictions to numerical calculations.
Comments:
16 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1510.00751 [pdf]
PRD(2016)·35 citations
13
[Submitted on 3 Oct 2015] (cross-list from nucl-ex)
3D Structure and Nuclear Targets
R. Dupré🇫🇷 · S. Scopetta🇮🇹
Recent experimental and theoretical ideas are laying the ground for a new era in the knowledge of the parton structure of nuclei. We report on two promising directions beyond inclusive deep inelastic scattering experiments, aimed at, among other goals, unveiling the three dimensional structure of the bound nucleon. The 3D structure in coordinate space can be accessed through deep exclusive processes, whose non-perturbative content is parametrized in terms of generalized parton distributions. In this way the distribution of partons in the transverse plane will be obtained, providing a pictorial view of the realization of the European Muon Collaboration effect. In particular, we show how, through the generalized parton distribution framework, non nucleonic degrees of freedom in nuclei can be unveiled. Analogously, the momentum space 3D structure can be accessed by studying transverse momentum dependent parton distributions in semi-inclusive deep inelastic scattering processes. The status of measurements is also summarized, in particular novel coincidence measurements at high luminosity facilities, such as Jefferson Laboratory. Finally the prospects for the next years at future facilities, such as the 12~GeV Jefferson Laboratory and the Electron Ion Collider, are presented.
Comments:
12 pages, 14 figures, contribution to the EPJA topical issue on "3D Structure of the Nucleon"
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1510.00794 [pdf]
EPJA(2016)·35 citations
14
[Submitted on 3 Oct 2015] (cross-list from hep-ph)
The nature of near-threshold XYZ states
Martin Cleven🇨🇳 · Feng-Kun Guo🇩🇪 · Christoph Hanhart🇩🇪 · Qian Wang🇩🇪 · Qiang Zhao🇨🇳
We demonstrate that the recently observed $X$ , $Y$ , $Z$ states cannot be purely from kinematic effect. Especially the narrow near-threshold structures in elastic channels call for nearby poles of the $S$ -matrix which are qualified as states. We propose a way to distinguish cusp effects from genuine states and demonstrate that (not all of) the recently observed $X$ , $Y$ , $Z$ states cannot be purely from kinematic effects. Especially, we show that the narrow near-threshold structures in elastic channels call for nearby poles of the $S$ -matrix, since the normal kinematic cusp effect cannot produce that narrow structures in the elastic channels in contrast to genuine $S$ -matrix poles. In addition, it is also discussed how spectra can be used to distinguish different scenarios proposed for the structure of those poles, such as hadro-quarkonia, tetraquarks and hadronic molecules. The basic tool employed is heavy quark spin symmetry.
Comments:
8 pages, 5 figures, proceeding of NSTAR2015, Osaka, Japan
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1510.00854 [pdf]
JPS Conf.Proc.(2016)·6 citations
15
[Submitted on 3 Oct 2015] (cross-list from hep-ph)
Deduction of $M (S i g ma p i)$ for $L amb d a (1405)$ with mixed $T_{S i g ma p i l e f t a r r o w K^{-} p} an d T_{S i g ma p i l e f t a r r o w S i g ma p i}$ from Hemingway's data
Maryam Hassanvand🇯🇵 · Yoshinori Akaishi🇯🇵 · Toshimitsu Yamazaki🇯🇵
We formulated the $L amb d a (1405)$ (abbreviated as $L amb d a^{*}$ ) $r i g h t a r r o w (S i g ma p i)^{0}$ invariant-mass spectra produced in the $K^{-} + p r i g h t a r r o w S i g m a^{+} (1660) + p i^{-}$ , followed by $S i g m a^{+} (1660) r i g h t a r r o w L amb d a (1405) + p i^{+} r i g h t a r r o w S i g ma p i + p i^{+}$ , processes at $p (K^{-}) = 4.2$ GeV/ $c$ , in which both the incident channel for a quasi-bound $K^{-} p$ state and its decay process to $(S i g ma p i)^{0}$ were taken into account realistically. We calculated $M (S i g ma p i)$ spectral shapes using mixed transition matrices, $T_{21} = T_{S i g ma p i l e f t a r r o w K^{-} p}$ and $T_{22} = T_{S i g ma p i l e f t a r r o w S i g ma p i}$ , for various theoretical models involving $L amb d a^{*}$ . The asymmetric spectra were compared to old experimental data of Hemingway, and it was found that the mixing of the two channels, written as $(1 - f), T_{21} + f, T_{22}$ , gave a better result than considering the individual channels, yielding $f = 0.37 6_{- 0.019}^{+ 0.021}$ , $M (L amb d a^{*}) = 1406. 6_{- 3.3}^{+ 3.4}$ MeV/ $c^{2}$ and $G amma = 70 p m 2$ MeV, nearly consistent with the 2014 PDG values.
Comments:
7 pages, 5 figures, Phys. Rev. C (2015), in press
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1510.00870 [pdf]
PRC(2015)·1 citation
16
[Submitted on 4 Oct 2015] (cross-list from hep-lat)
Instructive discussion of an effective block algorithm for baryon-baryon correlators
Hidekatsu Nemura🇯🇵
We describe an approach for the efficient calculation of a large number of four-point correlation functions for various baryon-baryon (BB) channels, which are the primary quantities for studying the nuclear and hyperonic nuclear forces from lattice quantum chromodynamics. Using the four-point correlation function of a proton- $Λ$ system as a specific example, we discuss how an effective block algorithm significantly reduces the number of iterations. The effective block algorithm is applied to calculate 52 channels of the four-point correlation functions from nucleon $-$ nucleon to $Ξ - Ξ$ , in order to study the complete set of isospin symmetric BB interactions. The elapsed times measured for hybrid parallel computation on BlueGene/Q demonstrate that the performance of the present algorithm is reasonable for various combinations of the number of OpenMP threads and the number of MPI nodes. The numerical results are compared with the results obtained using the unified contraction algorithm for all computed sites of the 52 four-point correlators.
Comments:
31 pages, 4 figures, minor changes including correction of typo, matches published version
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1510.00903 [pdf]
Comput.Phys.Commun.(2016)·12 citations
17
[Submitted on 4 Oct 2015] (cross-list from hep-ph)
Photoproduction of the Scalar Meson $f_{0} (500)$
Je-Hee Lee🇰🇷 · Hui-Young Ryu🇰🇷 · Byung-Geel Yu🇰🇷 · Hyun-Chul Kim🇰🇷
In the present talk, we report a recent investigation on photoproduction of the $γ N \to f_{0} (500) N$ within a framework of the effective Lagrangian. We include the nucleon resonances with pin $1/2$ in the $s$ channel. The coupling constants have been etermined by assuming that the decay process $N^{*} \to (π π)_{I = 0, J = 0} N$ can be regarded as $N^{*} \to f_{0} (500) N$ . We discuss the numerical results for the total cross sections and possible extension of the present work.
Comments:
4 pages, 5 figures. A contribution to The 10th International Workshop on the Physics of Excited Nucleons (NSTAR2015) held in Osaka University, May 25(Mon)-28(Thu), 2015
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1510.00929 [pdf]
JPS Conf.Proc.(2016)·0 citations
18
[Submitted on 5 Oct 2015] (cross-list from hep-ph)
Spectrum of heavy baryons in the quark model
Tetsuya Yoshida🇯🇵 · Emiko Hiyama🇯🇵 · Atsushi Hosaka🇯🇵 · Makoto Oka🇯🇵 · Katsunori Sadato🇯🇵
Single- and double- heavy baryons are studied in the constituent quark model. The model Hamiltonian is chosen as a standard one with two exceptions : (1) The color-Coulomb term depend on quark masses, and (2) an antisymmetric $L S$ force is introduced. Model parameters are fixed by the strange baryon spectra, $Λ$ and $Σ$ baryons. The masses of the observed charmed and bottomed baryons are, then, fairly well reproduced. Our focus is on the low-lying negative-parity states, in which the heavy baryons show specific excitation modes reflecting the mass differences of heavy and light quarks. By changing quark masses from the SU(3) limit to the strange quark mass, further to the charm and bottom quark masses, we demonstrate that the spectra change from the SU(3) symmetry patterns to the heavy quark symmetry ones.
Comments:
25 pages with 22 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1510.01067 [pdf]
PRD(2015)·283 citations
19
[Submitted on 5 Oct 2015] (cross-list from hep-ph)
Entropy production in chemically non-equilibrium quark-gluon plasma created in central Pb+Pb collisions at LHC energies
V. Vovchenko🇩🇪 · M.I. Gorenstein🇩🇪 · L.M. Satarov🇩🇪 · I.N. Mishustin🇩🇪 · L.P. Csernai🇳🇴 · I. Kisel🇩🇪 · H. Stoecker🇩🇪
We study the possibility that partonic matter produced at early stage of ultrarelativistic heavy-ion collisions is out of chemical equilibrium. It is assumed that initially this matter is mostly composed of gluons, but quarks and antiquarks are produced at later times. The dynamical evolution of partonic system is described by the Bjorken-like ideal hydrodynamics with a time dependent quark fugacity. The results of this model are compared with those obtained by assuming the complete chemical equilibrium of partons already at the initial stage. It is shown that in a chemically non-equilibrium scenario the entropy gradually increases, and about 25% of the total final entropy is generated during the hydrodynamic evolution of deconfined matter. We argue that the (anti)quark suppression included in this approach may be responsible for reduced (anti)baryon to meson ratios observed in heavy-ion collisions at LHC energies.
Comments:
19 pages, 6 figures, minor changes to match published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1510.01235 [pdf]
PRC(2016)·15 citations
20
[Submitted on 5 Oct 2015] (cross-list from nucl-ex)
The Proton Radius from Electron Scattering Data
Douglas W. Higinbotham · Al Amin Kabir · Vincent Lin · David Meekins · Blaine Norum · Brad Sawatzky
[Background] The proton charge radius extracted from recent muonic hydrogen Lamb shift measurements is significantly smaller than that extracted from atomic hydrogen and electron scattering measurements. [Purpose] In an attempt to understand the discrepancy, we review high-precision electron scattering results from Mainz, Jefferson Lab, Saskatoon and Stanford. [Method] We make use of stepwise regression techniques using the $F$ -test as well as the Akaike information criterion to systematically determine the predictive variables to use for a given set and range of electron scattering data as well as to provide multivariate error estimates. [Results] Starting with the precision, low four-momentum transfer ( $Q^{2}$ ) data from Mainz (1980) and Saskatoon (1974), we find that a stepwise regression of the Maclaurin series using the $F$ -test as well as the Akaike information criterion justify using a linear extrapolation which yields a value for the proton radius that is consistent with the result obtained from muonic hydrogen measurements. Applying the same Maclaurin series and statistical criteria to the 2014 Rosenbluth results on $G_{E}$ from Mainz, we again find that the stepwise regression tends to favor a radius consistent with the muonic hydrogen radius but produces results that are extremely sensitive to the range of data included in the fit. Making use of the high- $Q^{2}$ data on $G_{E}$ to select functions which extrapolate to high $Q^{2}$ , we find that a Padé ( $N = M = 1$ ) statistical model works remarkably well, as does a dipole function with a 0.84 fm radius, $G_{E} (Q^{2}) = (1 + Q^{2} /0.66 GeV^{2})^{- 2}$ . [Conclusions] From this statistical analysis, we conclude that the electron scattering result and the muonic hydrogen result are consistent. It is the atomic hydrogen results that are the outliers.
Comments:
10 pages, 7 figures, 7 tables
Subjects:
Nuclear Experiment (nucl-ex); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
arXiv:
1510.01293 [pdf]
PRC(2016)·94 citations

Affiliations

first authorsco-authorsvia INSPIRE