Nuclear Theory·nucl-th

Tuesday·November 10, 2015

13 papers—6 primary·7 cross-listed

07
Instanton-dyon Ensemble with two Dynamical Quarks: the Chiral Symmetry Breaking
Rasmus Larsen🇺🇸 · Edward Shuryak🇺🇸
This is the second paper of the series aimed at understanding the ensemble of instanton-dyons, now with two flavors of light dynamical quarks. The partition function is appended by the fermionic factor, $(d e tT)^{N_{f}}$ and Dirac eigenvalue spectra at small values are derived from the numerical simulation of 64 and 128 dyons. Those spectra show clear chiral symmetry breaking pattern at high dyon density.
↳ hep-phhep-latnucl-thPRD(2016)·43 citations
08
Nuclear Parity Violation from Lattice QCD
Thorsten Kurth · Evan Berkowitz · Enrico Rinaldi · Pavlos Vranas · Amy Nicholson · Mark Strother · Andre Walker-Loud
The electroweak interaction at the level of quarks and gluons are well understood from precision measurements in high energy collider experiments. Relating these fundamental parameters to Hadronic Parity Violation in nuclei however remains an outstanding theoretical challenge. One of the most interesting observables in this respect is the parity violating hadronic neutral current: it is hard to measure in collider experiments and is thus the least constrained observable of the Standard Model. Precision measurements of parity violating transitions in nuclei can help to improve these constraints. In these systems however, the weak interaction is masked by effects of the seven orders of magnitude stronger non-perturbative strong interaction. Therefore, in order to relate experimental measurements of the parity violating pion-nucleon couplings to the fundamental Lagrangian of the SM, these non-perturbative effects have to be well understood. In this paper, we are going to present a Lattice QCD approach for computing the $Δ I = 2$ parity violating matrix element in proton proton scattering. This process does not involve disconnected diagrams in the isospin symmetric limit and is thus a perfect testbed for studying the feasibility of the more involved calculation of the parity violating pion-nucleon coupling.
↳ hep-lathep-phnucl-thPoS(2016)·14 citations
09
Two-nucleon scattering in multiple partial waves
Amy Nicholson🇺🇸 · Evan Berkowitz🇺🇸 · Enrico Rinaldi🇺🇸 · Pavlos Vranas🇺🇸 · Thorsten Kurth🇺🇸 · Balint Joo🇺🇸 · Mark Strother🇺🇸 · Andre Walker-Loud🇺🇸
We determine scattering phase shifts for S,P,D, and F partial wave channels in two-nucleon systems using lattice QCD methods. We use a generalization of Luscher's finite volume method to determine infinite volume phase shifts from a set of finite volume ground- and excited-state energy levels on two volumes, V=(3.4 fm)^3 and V=(4.5 fm)^3. The calculations are performed in the SU(3)-flavor limit, corresponding to a pion mass of approximately 800 MeV. From the energy dependence of the phase shifts we are able to extract scattering parameters corresponding to an effective range expansion.
↳ hep-latnucl-thPoS(2016)·7 citations
10
Low energy scattering phase shifts for meson-baryon systems
William Detmold🇺🇸 · Amy Nicholson🇺🇸
In this work, we calculate meson-baryon scattering phase shifts in four channels using lattice QCD methods. From a set of calculations at four volumes, corresponding to spatial sizes of 2, 2.5, 3, and 4 fm, and a pion mass of m_pi ~ 390 MeV, we determine the scattering lengths and effective ranges for these systems at the corresponding quark masses. We also perform the calculation at a lighter quark mass, m_pi ~ 230 MeV, on the largest volume. Using these determinations, along with those in previous work, we perform a chiral extrapolation of the scattering lengths to the physical point after correcting for the effective range contributions using the multi-volume calculations performed at m_pi ~ 390 MeV.
↳ hep-latnucl-thPRD(2016)·31 citations
11
Proximity of $f_{0} (1500)$ and $f_{0} (1710)$ to the scalar glueball
Amir H. Fariborz🇺🇸 · Azizollah Azizi🇮🇷 · Abdorreza Asrar🇮🇷
Within a nonlinear chiral Lagrangian framework, the underlying mixings among quark-antiquark, four-quark and glue components of $f_{0} (1500)$ and $f_{0} (1710)$ are studied in a global picture that includes all isosinglet scalar mesons below 2 GeV. The quark components are introduced in the Lagrangian in terms of two separate nonets (a quark-antiquark nonet and a four-quark nonet) which can mix with each other and with a scalar glueball. The free parameters of the Lagrangian are studied by a simultaneous fit to more than 20 experimental data and constraints on the mass spectrum, decay widths, and decay ratios of the isosinglet scalars below 2 GeV. Moreover, constraints on the mass spectrum and decay widths of isodoublet and isovector scalars below 2 GeV as well as pion-pion scattering amplitude are also taken into account. The insights gained in this global picture, due to the complexities of the mixings as well as the experimental uncertainties, are mainly qualitative but are relatively robust, and reveal that the lowest scalar glueball hides between $f_{0} (1500)$ and $f_{0} (1710)$ , resulting in a considerable mixing with various quark components of these two states. The overall current experimental and theoretical uncertainties do not allow to pin down the exact glue components of isosinglet states, nevertheless it is shown that the $f_{0} (1500)$ and $f_{0} (1710)$ have the highest glue component. While this global study does not allow precision predictions for each individual state, it provides useful "family" correlations among the isosinglet states that are found insightful in probing the substructure of all scalars, in general, and the isosinglets, in particular. The overall estimate of the scalar glueball mass is found to be $1.58 \pm 0.18$ GeV.
↳ hep-phhep-exhep-latnucl-thPRD(2015)·15 citations
12
Presupernova neutrinos: realistic emissivities from stellar evolution
Kelly M. Patton🇺🇸 · Cecilia Lunardini🇺🇸 · Robert J. Farmer🇺🇸
We present a new calculation of neutrino emissivities and energy spectra from a massive star going through the advanced stages of nuclear burning (presupernova) in the months before becoming a supernova. The contributions from beta decay and electron capture, pair annihilation, plasmon decay, and the photoneutrino process are modeled in detail, using updated tabulated nuclear rates. We also use realistic conditions of temperature, density, electron fraction and nuclear isotopic composition of the star from the state of the art stellar evolution code MESA. Results are presented for a set of progenitor stars with mass between 15 $M_{⊙}$ and 30 $M_{⊙}$ . It is found that beta processes contribute substantially to the neutrino emissivity above realistic detection thresholds of few MeV, at selected positions and times in the evolution of the star.
↳ astro-ph.SRnucl-thApJ(2017)·51 citations
13
Sensitivity to oscillation with a sterile fourth generation neutrino from ultra-low threshold neutrino-nucleus coherent scattering
Bhaskar Dutta · Yu Gao · Andrew Kubik · Rupak Mahapatra · Nader Mirabolfathi · Louis E. Strigari · Joel W. Walker
We discuss prospects for probing short-range sterile neutrino oscillation using neutrino-nucleus coherent scattering with ultra-low energy ( $\sim 10$ eV - 100 eV) recoil threshold cryogenic Ge detectors. The analysis is performed in the context of a specific and contemporary reactor-based experimental proposal, developed in cooperation with the Nuclear Science Center at Texas A\&M University, and references developing technology based upon economical and scalable detector arrays. The baseline of the experiment is substantially shorter than existing measurements, as near as about 2 meters from the reactor core, and is moreover variable, extending continuously up to a range of about 10 meters. This proximity and variety combine to provide extraordinary sensitivity to a wide spectrum of oscillation scales, while facilitating the tidy cancellation of leading systematic uncertainties in the reactor source and environment. With 100~eV sensitivity, for exposures on the order of 200 kg $\cdot$ y, we project an estimated sensitivity to first/fourth neutrino oscillation with a mass gap $Δ m^{2} \sim 1 eV^{2}$ at an amplitude $sin^{2} 2 θ \sim 1 0^{- 1}$ , or $Δ m^{2} \sim 0.2 eV^{2}$ at unit amplitude. Larger exposures, around 5,000 kg $\cdot$ y, together with 10 eV sensitivity are capable of probing more than an additional order of magnitude in amplitude.
↳ hep-phhep-exnucl-exnucl-thPRD(2016)·71 citations

Affiliations

first authorsco-authorsvia INSPIRE

Instanton-dyon Ensemble with two Dynamical Quarks: the Chiral Symmetry Breaking

Nuclear Parity Violation from Lattice QCD

Two-nucleon scattering in multiple partial waves

Low energy scattering phase shifts for meson-baryon systems

Proximity of f0​(1500) and f0​(1710) to the scalar glueball

Presupernova neutrinos: realistic emissivities from stellar evolution

Sensitivity to oscillation with a sterile fourth generation neutrino from ultra-low threshold neutrino-nucleus coherent scattering

Affiliations

Proximity of $f_{0} (1500)$ and $f_{0} (1710)$ to the scalar glueball