Add t in dvmp; add a place holder for InvQuant in REC

WIP: Add t in dvmp; add a place holder for InvQuant with limited track selection in REC

benchmarks/dvmp/analysis/dvmp.h

@@ -28,7 +28,7 @@ namespace util {
   // for structure functions
 
   struct inv_quant { // add more when needed
-    double nu, Q2, x;
+    double nu, Q2, x, t;
   };
 
   // for simu
@@ -36,10 +36,12 @@ namespace util {
   {
     ROOT::Math::PxPyPzMVector q(parts[0] - parts[2]);
     ROOT::Math::PxPyPzMVector P(parts[3]);
+    ROOT::Math::PxPyPzMVector Delta(parts[6] - parts[3]);
 
     double    nu         = q.Dot(P) / P.mass();
     double    Q2         = -q.Dot(q);
-    inv_quant quantities = {nu, Q2, Q2 / 2. / P.mass() / nu};
+    double t = Delta.Dot(Delta);
+    inv_quant quantities = {nu, Q2, Q2 / 2. / P.mass() / nu, t};
     return quantities;
   }