Ab initio calculation of the $$np \to d ³$$ radiative capture process
- Univ. of Washington, Seattle, WA (United States)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Univ. of Barcelona, Barcelona (Spain)
- The City College of New York, New York, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
In this study, lattice QCD calculations of two-nucleon systems are used to isolate the short-distance two-body electromagnetic contributions to the radiative capture process $$np \to d\gamma$$, and the photo-disintegration processes $$\gamma^{(\ast)} d \to np$$. 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 $$m_\pi \sim 450$$ and 806 MeV, and are combined with pionless nuclear effective field theory to determine these low-energy inelastic processes. Extrapolating to the physical pion mass, a cross section of $$\sigma^{lqcd}(np\to d\gamma)=332.4({\tiny \begin{array}{l}+5.4 \\ - 4.7\end{array}})\ mb$$ is obtained at an incident neutron speed of $$v=2,200\ m/s$$, consistent with the experimental value of $$\sigma^{expt}(np \to d\gamma) = 334.2(0.5)\ mb$$.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
- Sponsoring Organization:
- DOE Office of Science; USDOE
- Contributing Organization:
- NPLQCD Collaboration
- Grant/Contract Number:
- AC02-05CH11231; FG02-04ER41302; FG02-00ER41132; AC05-00OR22725; SC0010495; AC05-06OR23177
- OSTI ID:
- 1221536
- Alternate ID(s):
- OSTI ID: 1224626
- Report Number(s):
- JLAB-THY--15-2045; DOE/OR/23177--3346; arXiv:1505.02422
- Journal Information:
- Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 13 Vol. 115; ISSN 0031-9007; ISSN PRLTAO
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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