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Nuclear Theory·nucl-th

Wednesday·August 9, 2017

8 papers—3 primary·5 cross-listed

All8Primary3Cross-lists5
  1. 04

    Reactor Fuel Fraction Information on the Antineutrino Anomaly

    C. Giunti🇮🇹 · X.P. Ji🇨🇳 · M. Laveder🇮🇹 · Y.F. Li🇨🇳 · B.R. Littlejohn🇺🇸

    We analyzed the evolution data of the Daya Bay reactor neutrino experiment in terms of short-baseline active-sterile neutrino oscillations taking into account the theoretical uncertainties of the reactor antineutrino fluxes. We found that oscillations are disfavored at with respect to a suppression of the reactor antineutrino flux and at with respect to variations of the and fluxes. On the other hand, the analysis of the rates of the short-baseline reactor neutrino experiments favor active-sterile neutrino oscillations and disfavor the suppression of the flux at and variations of the and fluxes at . We also found that both the Daya Bay evolution data and the global rate data are well-fitted with composite hypotheses including variations of the or fluxes in addition to active-sterile neutrino oscillations. A combined analysis of the Daya Bay evolution data and the global rate data shows a slight preference for oscillations with respect to variations of the and fluxes. However, the best fits of the combined data are given by the composite models, with a preference for the model with an enhancement of the flux and relatively large oscillations.

    ↳ hep-phhep-exnucl-exnucl-thJHEP(2017)·58 citations
  2. 05

    Improved limits for Higgs-portal dark matter from LHC searches

    Martin Hoferichter🇺🇸 · Philipp Klos🇩🇪 · Javier Menéndez🇯🇵 · Achim Schwenk🇩🇪

    Searches for invisible Higgs decays at the Large Hadron Collider constrain dark matter Higgs-portal models, where dark matter interacts with the Standard Model fields via the Higgs boson. While these searches complement dark matter direct-detection experiments, a comparison of the two limits depends on the coupling of the Higgs boson to the nucleons forming the direct-detection nuclear target, typically parameterized in a single quantity . We evaluate using recent phenomenological and lattice-QCD calculations, and include for the first time the coupling of the Higgs boson to two nucleons via pion-exchange currents. We observe a partial cancellation for Higgs-portal models that makes the two-nucleon contribution anomalously small. Our results, summarized as , show that the uncertainty of the Higgs-nucleon coupling has been vastly overestimated in the past. The improved limits highlight that state-of-the-art nuclear physics input is key to fully exploiting experimental searches.

    ↳ hep-phastro-ph.COhep-exnucl-thPRL(2017)·124 citations
  3. 06

    Particle production at energies available at the CERN Large Hadron Collider within evolutionary model

    Yu. M. Sinyukov🇺🇦 · V. M. Shapoval🇺🇦

    The particle yields and particle number ratios in Pb+Pb collisions at the LHC energy TeV are described within the integrated hydrokinetic model (iHKM) at the two different equations of state (EoS) for the quark-gluon matter and the two corresponding hadronization temperatures, MeV and MeV. The role of particle interactions at the final afterburner stage of the collision in the particle production is investigated by means of comparison of the results of full iHKM simulations with those where the annihilation and other inelastic processes (except for resonance decays) are switched off after hadronization/particlization, similarly as in the thermal models. An analysis supports the picture of continuous chemical freeze-out in the sense that the corrections to the sudden chemical freeze-out results, which arise because of the inelastic reactions at the subsequent evolution times, are noticeable and improve the description of particle and number ratios. An important observation is that although the particle number ratios with switched-off inelastic reactions are quite different at different particlization temperatures which are adopted for different equations of state to reproduce experimental data, the complete iHKM calculations bring very close results in both cases.

    ↳ hep-phnucl-exnucl-thPRC(2018)·8 citations
  4. 07

    Gluon quasidistribution function at one loop

    Wei Wang🇨🇳 · Shuai Zhao🇨🇳 · Ruilin Zhu🇨🇳

    We study the unpolarized gluon quasidistribution function in the nucleon at one loop level in the large momentum effective theory. For the quark quasidistribution, power law ultraviolet divergences arise in the cut-off scheme and an important observation is that they all are subjected to Wilson lines. However for the gluon quasidistribution function, we first point out that the linear ultraviolet divergences also exist in the real diagram which is not connected to any Wilson line. We then study the one loop corrections to parton distribution functions in both cut-off scheme and dimensional regularization to deal with the ultraviolet divergences. In addition to the ordinary quark and gluon distributions, we also include the quark to gluon and gluon to quark splitting diagrams. The complete one-loop matching factors between the quasi and light cone parton distribution functions are presented in the cut-off scheme. We derive the evolution equation for quasi parton distribution functions, and find that the evolution kernels are identical to the DGLAP evolution kernels.

    ↳ hep-phhep-exhep-latnucl-thEPJC(2018)·97 citations
  5. 08

    Two-photon exchange correction to the hyperfine splitting in muonic hydrogen

    O. Tomalak🇩🇪

    We reevaluate the Zemach, recoil and polarizability corrections to the hyperfine splitting in muonic hydrogen expressing them through the low-energy proton structure constants and obtain the precise values of the Zemach radius and two-photon exchange (TPE) contribution. The uncertainty of TPE correction to S energy levels in muonic hydrogen of 105 ppm exceeds the ppm accuracy level of the forthcoming 1S hyperfine splitting measurements at PSI, J-PARC and RIKEN-RAL.

    ↳ hep-phnucl-exnucl-thphysics.atom-phEPJC(2017)·37 citations

Affiliations

first authorsco-authorsvia INSPIRE