Nuclear Theory·nucl-th

Wednesday·March 30, 2016

15 papers—6 primary·9 cross-listed

07
[Submitted on 21 Mar 2016] (cross-list from hep-lat)
Polyakov loop in 2+1 flavor QCD from low to high temperatures
A. Bazavov🇺🇸 · N. Brambilla🇩🇪 · H.-T. Ding🇨🇳 · P. Petreczky🇺🇸 · H.-P. Schadler🇺🇸 · A. Vairo🇩🇪 · J. H. Weber🇩🇪
We study the free energy of a static quark in QCD with 2+1 flavors in a wide temperature region, 116 MeV $< T <$ 5814 MeV, using the highly improved staggered quark (HISQ) action. We analyze the transition region in detail, obtain the entropy of a static quark, show that it peaks at temperatures close to the chiral crossover temperature and also revisit the temperature dependence of the Polyakov loop susceptibilities using gradient flow. We discuss the implications of our findings for the deconfinement and chiral crossover phenomena at physical values of the quark masses. Finally a comparison of the lattice results at high temperatures with the weak-coupling calculations is presented.
Comments:
RevTeX, 21 pages, 20 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1603.06637 [pdf]
PRD(2016)·147 citations
08
[Submitted on 28 Mar 2016] (cross-list from hep-ph)
Effective field theory investigations of the XYZ puzzle
Jorge Segovia🇩🇪
Quantum Chromodynamics, the theory of strong interactions, predicts several types of bound states. Among them are mesons ( $q q ˉ$ ) and baryons ( $q q q$ ), which have been the only states observed in experiments for years. However, in the last decade, many states that do not fit this picture have been observed at $B$ -factories (BaBar, Belle and CLEO), at $τ$ -charm facilities (CLEO-c, BESIII) and also at proton-proton colliders (CDF, D0, LHCb, ATLAS, CMS). There is growing evidence that at least some of the new charmonium- and bottomonium-like states, the so-called XYZ mesons, are new forms of matter such as quark-gluon hybrids, mesonic molecules or different arrangements of tetraquarks, pentaquarks... Effective Field Theories (EFTs) have been constructed for heavy-quark-antiquark bound states, but a general study of the XYZ mesons within the same framework has not yet been done. The scope of this conference proceedings is to discuss the possibilities we have in developing novel EFTs that, characterizing the conventional quarkonium states, facilitate also the systematic and model-independent description of the new exotic matter, in particular, the hybrid mesons.
Comments:
5 pages; contribution to the proceedings of the FAIRNESS2016: Workshop for young scientists with research interests focused on physics at FAIR. 14-19 February 2016. Garmisch-Partenkirchen, Germany
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1603.08527 [pdf]
J.Phys.Conf.Ser.(2016)·3 citations
09
[Submitted on 29 Mar 2016] (cross-list from hep-ph)
Direct Neutrino Mass Experiments and Exotic Charged Current Interactions
Patrick Otto Ludl🇩🇪 · Werner Rodejohann🇩🇪
We study the effect of exotic charged current interactions on the electron energy spectrum in tritium decay, focussing on the KATRIN experiment and a possible modified setup that has access to the full spectrum. Both sub-eV and keV neutrino masses are considered. We perform a fully relativistic calculation and take all possible new interactions into account, demonstrating the possible sizable distortions in the energy spectrum.
Comments:
38 pages, 6 figures, no diphotons. Comments and references added
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1603.08690 [pdf]
JHEP(2016)·40 citations
10
[Submitted on 29 Mar 2016] (cross-list from hep-ph)
Instantaneous Bethe-Salpeter Kernel for the Lightest Pseudoscalar Mesons
Wolfgang Lucha🇦🇹 · Franz F. Schöberl🇦🇹
Starting from a phenomenologically successful, numerical solution of the Dyson-Schwinger equation that governs the quark propagator, we reconstruct in detail the interaction kernel that has to enter the instantaneous approximation to the Bethe-Salpeter equation to allow us to describe the lightest pseudoscalar mesons as quark-antiquark bound states exhibiting the (almost) masslessness necessary for them to be interpretable as the (pseudo) Goldstone bosons related to the spontaneous chiral symmetry breaking of quantum chromodynamics.
Comments:
12 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1603.08745 [pdf]
PRD(2016)·15 citations
11
[Submitted on 29 Mar 2016] (cross-list from hep-ph)
Decay width of $d^{*} (2380) \to N N π π$ processes
Yubing Dong🇨🇳 · Fei Huang🇨🇳 · Pengnian Shen🇨🇳 · Zongye Zhang🇨🇳
The decay widths of four-body double-pion decays $\ds \to p n π^{0} π^{0}$ , $\ds \to p n π^{+} π^{-}$ , and iso-scalar parts of $\ds \to pp π^{0} π^{-}$ and $\ds \to nn π^{+} π^{0}$ are explicitly calculated with the help of the $d^{*}$ wave function obtained in a chiral SU(3) quark model calculation. The effect of the dynamical structure on $\ds$ 's width is analyzed both in the single $ΔΔ$ channel and coupled $ΔΔ$ and $C C$ channel approximations. It is found that in the coupled-channel approximation, the obtained partial decay widths of $\ds \to p n π^{0} π^{0}$ , $\ds \to p n π^{+} π^{-}$ , and those of $d^{*}$ to the iso-scalar parts of $pp π^{0} π^{-}$ and $nn π^{+} π^{0}$ are about $7.4$ MeV, $16.4$ MeV, $3.5$ MeV and $3.5$ MeV, respectively As a consequence, the total width is about $64.5$ MeV. These widths are consistent with those estimated by using the corresponding cross section data in our previous investigation and also the observed data. But in the single $ΔΔ$ channel approximation, the widths are still almost 2-times larger than the measured values. Apparently, the explicitly calculated width together with the evaluated mass of $d^{*}$ in the coupled $ΔΔ$ and $C C$ channel approximation can well explain the observed data, which again supports our assertion that the $\ds$ resonance is a six-quark dominated exotic state.
Comments:
6 pages, 1 figure, 1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1603.08748 [pdf]
PRC(2016)·53 citations
12
[Submitted on 29 Mar 2016] (cross-list from hep-th)
Universality of anomalous conductivities in theories with higher-derivative holographic duals
Sašo Grozdanov🇳🇱 · Napat Poovuttikul🇳🇱
Anomalous chiral conductivities in theories with global anomalies are independent of whether they are computed in a weakly coupled quantum (or thermal) field theory, hydrodynamics, or at infinite coupling from holography. While the presence of dynamical gauge fields and mixed, gauge-global anomalies can destroy this universality, in their absence, the non-renormalisation of anomalous Ward identities is expected to be obeyed at all intermediate coupling strengths. In holography, bulk theories with higher-derivative corrections incorporate coupling constant corrections to the boundary theory observables in an expansion around infinite coupling. In this work, we investigate the coupling constant dependence and universality of anomalous conductivities (and thus of the anomalous Ward identities) in general, four-dimensional systems that possess asymptotically anti-de Sitter holographic duals with a non-extremal black brane in five dimensions, and anomalous transport introduced into the boundary theory via the bulk Chern-Simons action. We show that in bulk theories with arbitrary gauge- and diffeomorphism-invariant higher-derivative actions, anomalous conductivities, which can incorporate an infinite series of (inverse) coupling constant corrections, remain universal. Owing to the existence of the membrane paradigm, the proof reduces to a construction of bulk effective theories at the horizon and the boundary. It only requires us to impose the condition of horizon regularity and correct boundary conditions on the fields. We also discuss ways to violate the universality by violating conditions for the validity of the membrane paradigm, in particular, by adding mass to the vector fields (a case with a mixed, gauge-global anomaly) and in bulk geometries with a naked singularity.
Comments:
V2: 29 pages, 1 figure, version published in JHEP
Subjects:
High Energy Physics — Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1603.08770 [pdf]
JHEP(2016)·20 citations
13
[Submitted on 29 Mar 2016] (cross-list from hep-ph)
Coherency in Neutrino-Nucleus Elastic Scattering
S. Kerman🇹🇼 · V. Sharma🇮🇳 · M. Deniz🇹🇼 · H.T. Wong🇹🇼 · J.-W. Chen🇹🇼 · H.B. Li🇹🇼 · S.T. Lin🇨🇳 · C.-P. Liu🇹🇼 · Q. Yue (TEXONO Collaboration)🇨🇳
Neutrino-nucleus elastic scattering provides a unique laboratory to study the quantum mechanical coherency effects in electroweak interactions, towards which several experimental programs are being actively pursued. We report results of our quantitative studies on the transitions towards decoherency. A parameter ( $α$ ) is identified to describe the degree of coherency, and its variations with incoming neutrino energy, detector threshold and target nucleus are studied. The ranges of $α$ which can be probed with realistic neutrino experiments are derived, indicating complementarity between projects with different sources and targets. Uncertainties in nuclear physics and in $α$ would constrain sensitivities in probing physics beyond the standard model. The maximum neutrino energies corresponding to $α$ >0.95 are derived.
Comments:
5 pages, 4 figures, 3 tables. V2 -- Published Version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1603.08786 [pdf]
PRD(2016)·77 citations
14
[Submitted on 29 Mar 2016] (cross-list from cond-mat.quant-gas)
Nonlinear Phenomena of Ultracold Atomic Gases in Optical Lattices: Emergence of Novel Features in Extended States
Gentaro Watanabe · B. Prasanna Venkatesh · Raka Dasgupta
The system of a cold atomic gas in an optical lattice is governed by two factors: nonlinearity originating from the interparticle interaction, and the periodicity of the system set by the lattice. The high level of controllability associated with such an arrangement allows for the study of the competition and interplay between these two, and gives rise to a whole range of interesting and rich nonlinear effects. This review covers the basic idea and overview of such nonlinear phenomena, especially those corresponding to extended states. This includes "swallowtail" loop structures of the energy band, Bloch states with multiple periodicity, and those in "nonlinear lattices", i.e., systems with the nonlinear interaction term itself being a periodic function in space.
Comments:
39 pages, 21 figures; review article to be published in a Special Issue of Entropy on "Non-Linear Lattice"
Subjects:
Quantum Gases (cond-mat.quant-gas); Superconductivity (cond-mat.supr-con); nlin.PS (nlin.PS); Nuclear Theory (nucl-th)
arXiv:
1603.08818 [pdf]
Entropy(2016)·7 citations
15
[Submitted on 29 Mar 2016] (cross-list from hep-ph)
Light-front representation of chiral dynamics with Delta isobar and large-N_c relations
C. Granados🇺🇸 · C. Weiss🇺🇸
Transverse densities describe the spatial distribution of electromagnetic current in the nucleon at fixed light-front time. At peripheral distances b = O(M_pi^{-1}) the densities are governed by chiral dynamics and can be calculated model-independently using chiral effective field theory (EFT). Recent work has shown that the EFT results can be represented in first-quantized form, as overlap integrals of chiral light-front wave functions describing the transition of the nucleon to soft-pion-nucleon intermediate states, resulting in a quantum-mechanical picture of the peripheral transverse densities. We now extend this representation to include intermediate states with Delta isobars and implement relations based on the large-N_c limit of QCD. We derive the wave function overlap formulas for the Delta contributions to the peripheral transverse densities by way of a three-dimensional reduction of relativistic chiral EFT expressions. Our procedure effectively maintains rotational invariance and avoids the ambiguities with higher-spin particles in the light-front time-ordered approach. We study the interplay of pi-N and pi-Delta intermediate states in the quantum-mechanical picture of the densities in a transversely polarized nucleon. We show that the correct N_c-scaling of the charge and magnetization densities emerges as the result of the particular combination of currents generated by intermediate states with degenerate N and Delta. The off-shell behavior of the chiral EFT is summarized in contact terms and can be studied easily. The methods developed here can be applied to other peripheral densities and to moments of the nucleon's generalized parton distributions.
Comments:
35 pages, 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1603.08881 [pdf]
JHEP(2016)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE