Proton-proton fusion in pionless effective theory
  The proton-proton fusion reaction, $pp\to de^+\nu$, is studied in pionless effective field theory (EFT) with di-baryon fields up to next-to leading order. With the aid of the di-baryon fields, the effective range corrections are naturally resummed up to the infinite order and thus the calculation is greatly simplified. Furthermore, the low-energy constant which appears in the axial-current-di-baryon-di-baryon contact vertex is fixed through the ratio of two- and one-body matrix elements which reproduces the tritium lifetime very precisely. As a result we can perform a parameter free calculation for the process. We compare our numerical result with those from the accurate potential model and previous pionless EFT calculations, and find a good agreement within the accuracy better than 1%. 
S. Ando (1 and 2), J.W. Shin (1), C.H. Hyun (3), S.W. Hong (1), and K.   Kubodera (4) ((1) Sungkyunkwan U., (2) U. of Manche...