Study of e+e−→pp¯ in the vicinity of ψ(3770)

Using 2917 pb−1 of data accumulated at 3.773 GeV , 44.5 pb−1 of data accumulated at 3.65 GeV and data accumulated during a ψ(3770) line-shape scan with the BESIII detector, the reaction e+e−→pp¯ is studied considering a possible interference between resonant and continuum amplitudes. The cross section of e+e−→ψ(3770)→pp¯ , σ(e+e−→ψ(3770)→pp¯) , is found to have two solutions, determined to be (0.059−0.020+0.070±0.012) pb with the phase angle ϕ=(255.8−26.6+39.0±4.8)° ( <0.166 pb at the 90% confidence level), or σ(e+e−→ψ(3770)→pp¯)=(2.57−0.13+0.12±0.12) pb with ϕ=(266.9−6.3+6.1±0.9)° both of which agree with a destructive interference. Using the obtained cross section of ψ(3770)→pp¯ , the cross section of pp¯→ψ(3770) , which is useful information for the future PANDA experiment, is estimated to be either (9.8−3.9+11.8) nb ( <27.5 nb at 90% C.L.) or (425.6−43.7+42.9) nb .