Çetin, Serkant Ali2020-06-192020-06-192018-08-102470-00292470-0010https://hdl.handle.net/11411/2252https://doi.org/10.1103/PhysRevD.98.032006We observe the decay psi (3686) -> n (n) over bar for the first time and measure psi (3686) -> p (p) over bar with improved accuracy by using 1.07 x 10(8) psi (3686) events collected with the BESIII detector. The measured branching fractions are B(psi(3686) -> n (n) over bar) = (3.06 +/- 0.06 +/- 0.14) x 10(-4) and B(psi(3686) -> p (p) over bar) = (3.05 +/- 0.02 +/- 0.12) x 10(-4). Here, the first uncertainties are statistical, and the second ones are systematic. With the hypothesis that the polar angular distributions of the neutron and proton in the center-of-mass system obey 1 + alpha cos(2) theta, we determine the a parameters to be alpha(n (n) over bar) = 0.68 +/- 0.12 +/- 0.11 and alpha(p (p) over bar) = 1.03 +/- 0.06 +/- 0.03 for psi(3686) -> n (n) over bar and psi(3686) -> p (p) over bar, respectively.eninfo:eu-repo/semantics/openAccessDECAYSJ/PSIAMPLITUDESTESTSPHASEArticle2-s2.0-8505300854710.1103/PhysRevD.98.032006Q1WOS:000441334500003