Update pi0 analysis script

invariant mass and angle

benchmarks/ecal/scripts/emcal_pi0.cxx

@@ -28,8 +28,8 @@ void emcal_pi0(int n_events = 1e6, const char* out_fname = "./data/emcal_pi0_0Ge
   // Constraining the solid angle, but larger than that subtended by the detector
   // https://indico.bnl.gov/event/7449/contributions/35966/attachments/27177/41430/EIC-DWG-Calo-03192020.pdf
   // See a figure on slide 26
-  double cos_theta_min = std::cos(M_PI * (120.0 / 180.0));
-  double cos_theta_max = std::cos(M_PI);
+  double cos_theta_min = std::cos(M_PI * (160.0 / 180.0));
+  double cos_theta_max = std::cos(M_PI * (175.0 / 180.0));
 
   for (events_parsed = 0; events_parsed < n_events; events_parsed++) {
     // FourVector(px,py,pz,e,pdgid,status)