Updates EvtGen Code

[u/mrichter/AliRoot.git] / TEvtGen / EvtGenBase / EvtBlattWeisskopf.cpp

diff --git a/TEvtGen/EvtGenBase/EvtBlattWeisskopf.cxx b/TEvtGen/EvtGenBase/EvtBlattWeisskopf.cpp
similarity index 72%
rename from TEvtGen/EvtGenBase/EvtBlattWeisskopf.cxx
rename to TEvtGen/EvtGenBase/EvtBlattWeisskopf.cpp
index 0197355168017d59f715203bdca79d5eab17adf0..b41ec0b99514f54509db7c65843c5769e29dd8c7 100644 (file)
--- a/TEvtGen/EvtGenBase/EvtBlattWeisskopf.cxx
+++ b/TEvtGen/EvtGenBase/EvtBlattWeisskopf.cpp
@@ -2,7 +2,7 @@
 /*******************************************************************************
  * Project: BaBar detector at the SLAC PEP-II B-factory
  * Package: EvtGenBase
- *    File: $Id: EvtBlattWeisskopf.cc,v 1.6 2004/12/21 19:58:41 ryd Exp $
+ *    File: $Id: EvtBlattWeisskopf.cpp,v 1.3 2009-03-16 15:56:37 robbep Exp $
  *  Author: Alexei Dvoretskii, dvoretsk@slac.stanford.edu, 2001-2002
  *
  * Copyright (C) 2002 Caltech
@@ -64,24 +64,29 @@ double EvtBlattWeisskopf::operator()(double p) const
 
 double EvtBlattWeisskopf::compute(double p) const
 {
-  if(p < 0) {
-    
-    report(INFO,"EvtGen") << "Momentum " << p << " negative in form factor calculation" << endl;
-    assert(0);
-  }
-  else {
-    
-    double x = p*p*_radial*_radial;
-    
-    if(0 == _LL) return 1.;
-    else
-      if(1 == _LL) return sqrt(1.0/(1.0+x));
-      else
-       if(2 == _LL) return sqrt(1.0/(1.0+x/3.0+x*x/9.0));
-       else {
-         report(INFO,"EvtGen") << "Angular momentum " << _LL << " not implemented" << endl;
-         assert(0);
-       }
+
+  double value(1.0);
+
+  double z = p*_radial;
+  double zSq = z*z;
+
+  if (_LL == 0) {
+    value = 1.0;
+  } else if (_LL == 1) {
+    value = sqrt(1.0/(1.0 + zSq));
+  } else if (_LL == 2) {
+    value = sqrt(1.0/(zSq*(zSq + 3.0) + 9.0));
+  } else if (_LL == 3) {
+    double denom = zSq*(zSq*(zSq + 6.0) + 45.0) + 225.0;
+    value = sqrt(1.0/denom);
+  } else if (_LL == 4) {
+    double denom = zSq*(zSq*(zSq*(zSq + 10.0) + 135.0) + 1575.0) + 11025.0;
+    value = sqrt(1.0/denom);
+  } else if (_LL == 5) {
+    double denom = zSq*(zSq*(zSq*(zSq*(zSq + 15.0) + 315.0) + 6300.0) + 99225.0) + 893025.0;
+    value = sqrt(1.0/denom);
   }
-}
 
+  return value;
+
+}