About the parity-non-conserving asymmetry in (n)over-right-arrow+p -> d+gamma

The parity-non-conserving (pnc) asymmetry in (n) over right arrow + p --> d + gamma at thermal energies has recently been calculated using effective f ield-theory methods. A comparison of this calculation with much more elabor ate calculations performed in the 70's is made. This allows one to assess t he validity of this new approach as presently used. It is found to overshoo t the almost exact calculations by a factor close to 1.6 (a factor 2 when o nly the contribution involving the S-3(1) component of both the initial and final states is retained). This discrepancy is analyzed and found to origi nate from the over-simplified description of the deuteron and capture state s which underlies the new approach. The claim that earlier determinations o f the sign would be in error is also examined. It is found that the sign di screpancy is most probably due, instead, to the fact that the pion-nucleon interaction referred to by the authors corresponds to a parity-non-conservi ng potential with a sign opposite to what is currently used in the field. S ome estimates and constraints relative to the pnc pi NN coupling, h(pi)(1), which the above asymmetry is dependent on, are reviewed. (C) 2001 Elsevier Science B.V. All rights reserved.