Ab initio Calculation of the np → dy Radiative Capture Process
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PhysRevLett.115.132001.pdf
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Author(s)
Beane, Silas R.
Chang, Emmanuel
Detmold, William
Orginos, Kostas
Parreno, Assumpta
Savage, Martin J.
Tiburzi, Brian C.
Date Issued
September 2015
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Beane, Silas R., Emmanuel Chang, William Detmold, Kostas Orginos, Assumpta Parreno, Martin J. Savage, and Brian C. Tiburzi. "Ab initio Calculation of the np → dy Radiative Capture Process." Phys. Rev. Lett. 115, 132001 (September 2015). © 2015 American Physical Society
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Final published version
Abstract
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[superscript (*)]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[subscript 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[subscript π] ~ 806 MeV, using only lattice QCD inputs, a cross section σ[superscript 806 MeV] ~ 17 mb is found at an incident neutron speed of v = 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[superscript lqcd](np → dγ) = 334.9([+5.2 over -5.4]) mb is obtained at the same incident neutron speed, consistent with the experimental value of σ[superscript expt](np → dγ) = 334.2(0.5) mb.
MIT Department
Massachusetts Institute of Technology. Center for Theoretical Physics
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.115.132001
