Nucleon-nucleon scattering parameters in the limit of SU(3) flavor symmetry

Beane, Silas R.; Chang, Edmund K. M.; Cohen, Saul D.; Detmold, Will; Junnarkar, Parikshit; Lin, Huey‐Wen; Luu, Thomas; Orginos, Konstantinos; Parreño, A.; Savage, Martin J.; Walker-Loud, André

doi:10.1103/physrevc.88.024003

Cited by 121 publications

(239 citation statements)

References 80 publications

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“…Such systems are plagued by a reduced golden window compared to the single nucleon, presently limiting the length of plateaus from which to extract energy eigenvalues. A re-analysis of existing nuclear correlation functions generated by the NPLQCD collaboration [24,59,60] is planned in order to determine the utility of this work for such systems. Binding momenta and other scales appearing in multi-body hadronic systems may affect the form of the extrapolation used to remove the bias of the new estimator.…”

Section: Discussionmentioning

confidence: 99%

Statistics of baryon correlation functions in lattice QCD

Wagman

Savage²

2017

Phys. Rev. D

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A systematic analysis of the structure of single-baryon correlation functions calculated with lattice QCD is performed, with a particular focus on characterizing the structure of the noise associated with quantum fluctuations. The signal-to-noise problem in these correlation functions is shown, as long suspected, to result from a sign problem. The log-magnitude and complex phase are found to be approximately described by normal and wrapped normal distributions respectively. Properties of circular statistics are used to understand the emergence of a large time noise region where standard energy measurements are unreliable. Power-law tails in the distribution of baryon correlation functions, associated with stable distributions and "Lévy flights", are found to play a central role in their time evolution. A new method of analyzing correlation functions is considered for which the signal-to-noise ratio of energy measurements is constant, rather than exponentially degrading, with increasing source-sink separation time. This new method includes an additional systematic uncertainty that can be removed by performing an extrapolation, and the signal-to-noise problem re-emerges in the statistics of this extrapolation. It is demonstrated that this new method allows accurate results for the nucleon mass to be extracted from the large-time noise region inaccessible to standard methods. The observations presented here are expected to apply to quantum Monte Carlo calculations more generally. Similar methods to those introduced here may lead to practical improvements in analysis of noisier systems.

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Section: Discussionmentioning

confidence: 99%

Statistics of baryon correlation functions in lattice QCD

Wagman

Savage²

2017

Phys. Rev. D

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“…At the quark masses where the lattice calculations are performed, the cross sections are considerably smaller than at the physical point, primarily because the deuteron binding energy is larger. At m π ∼ 806 MeV, the scattering parameters, binding energy, and magnetic moments have been determined previously [33,40,41] and we can predict the scattering cross section using only lattice QCD inputs, with a median value σ 806 MeV ∼ 17 mb at v ¼ 2; 200 m=s. (Propagation of the uncertainties in the required inputs leads to a highly non-Gaussian distribution of σ 806 MeV [35].)…”

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confidence: 99%

“…For further details of the production at the SU(3)-symmetric point, see Refs. [33,40,41] and in particular, Ref. [35].…”

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confidence: 99%

Ab initioCalculation of thenp→dγRadiative Capture Process

et al. 2015

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Lattice QCD calculations of two-nucleon systems are used to isolate the short-distance two-body electromagnetic contributions to the radiative capture process np → dγ, and the photo-disintegration processes γ ðÃÞ d → np. In nuclear potential models, such contributions are described by phenomenological meson-exchange currents, while in the present work, they are determined directly from the quark and gluon interactions of QCD. Calculations of neutron-proton energy levels in multiple background magnetic fields are performed at two values of the quark masses, corresponding to pion masses of m π ∼ 450 and 806 MeV, and are combined with pionless nuclear effective field theory to determine the amplitudes for these low-energy inelastic processes. At m π ∼ 806 MeV, using only lattice QCD inputs, a cross section σ 806 MeV ∼ 17 mb is found at an incident neutron speed of v ¼ 2; 200 m=s. Extrapolating the short-distance contribution to the physical pion mass and combining the result with phenomenological scattering information and one-body couplings, a cross section of σ lqcd ðnp → dγÞ ¼ 334.9ð þ5.2 −5.4 Þ mb is obtained at the same incident neutron speed, consistent with the experimental value of σ expt ðnp → dγÞ ¼ 334.2ð0.5Þ mb. The radiative capture process, np → dγ, plays a critical role in big bang nucleosynthesis (BBN) as it is the starting point for the chain of reactions that form most of the light nuclei in the cosmos. Studies of radiative capture [1][2][3], and the inverse processes of deuteron electro-and photodisintegration, γ ðÃÞ d → np [4][5][6][7], have constrained these cross sections and have also provided critical insights into the interactions between nucleons and photons. They conclusively show the importance of non-nucleonic degrees of freedom in nuclei, which arise from meson-exchange currents (MECs) in the context of nuclear potential models [8,9]. Nevertheless, in the energy range relevant for BBN, experimental investigations are challenging [10]. For the analogous weak interactions of multinucleon systems, considerably less is known from experiment but these processes are equally important. The weak two-nucleon interactions currently contribute the largest uncertainty in calculations of the rate for proton-proton fusion in the Sun [11][12][13][14][15][16][17], and in neutrino-disintegration of the deuteron [18], which is a critical process needed to disentangle solar neutrino oscillations. Given the phenomenological importance of electroweak interactions in light nuclei, direct determinations from the underlying theory of strong interaction, quantum chromodynamics (QCD), are fundamental to future theoretical progress. Such determinations are also of significant phenomenological importance for calibrating long-baseline neutrino experiments and for investigations of double beta decay in nuclei. In this Letter, we take the initial steps towards meeting this challenge and present the first lattice QCD (LQCD) calculations of the np → dγ process. The results are in good agreement with experiment and show...

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“…It is also encouraging for calculations of moments of ∆(x, Q 2 ) in light nuclei, where this structure function provides a measure of exotic glue-the contributions from gluons not associated with individual nucleons in a nucleus. While nuclei are considerably more challenging to study in lattice QCD than simple hadrons like the φ meson, there has been considerable recent progress on lattice studies of the spectroscopy [28][29][30] and properties [31,32] of light nuclei. Although a procedure to measure ∆(x, Q 2 ) in nuclei was first outlined in 1989 [7], it is only recently in a letter of intent to Jefferson Lab [5] that an experimental measurement of ∆(x, Q 2 ) has been proposed, with the goal of measurements at low x on nitrogen targets.…”

Section: Discussionmentioning

confidence: 99%

Gluonic transversity from lattice QCD

Detmold

Shanahan

2016

Phys. Rev. D

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We present an exploratory study of the gluonic structure of the φ meson using lattice QCD (LQCD). This includes the first investigation of gluonic transversity via the leading moment of the twist-two double-helicity-flip gluonic structure function ∆(x, Q 2 ). This structure function only exists for targets of spin J ≥ 1 and does not mix with quark distributions at leading twist, thereby providing a particularly clean probe of gluonic degrees of freedom. We also explore the gluonic analogue of the Soffer bound which relates the helicity flip and non-flip gluonic distributions, finding it to be saturated at the level of 80%. This work sets the stage for more complex LQCD studies of gluonic structure in the nucleon and in light nuclei where ∆(x, Q 2 ) is an 'exotic glue' observable probing gluons in a nucleus not associated with individual nucleons.

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Nucleon-nucleon scattering parameters in the limit of SU(3) flavor symmetry

Cited by 121 publications

References 80 publications

Statistics of baryon correlation functions in lattice QCD

Statistics of baryon correlation functions in lattice QCD

Ab initioCalculation of thenp→dγRadiative Capture Process

Gluonic transversity from lattice QCD

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