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HepPDT Reference DocumentationHepPDT |
00001 // ---------------------------------------------------------------------- 00002 // 00003 // lifetime.cc 00004 // Author: Lynn Garren 00005 // 00006 // ---------------------------------------------------------------------- 00007 00008 #include "HepPDT/defs.h" 00009 #include "HepPDT/ResonanceStructure.hh" 00010 00011 namespace HepPDT { 00012 00013 Measurement ResonanceStructure::lifetime( ) const 00014 { 00015 // width = hbar / lifetime 00016 static double epsilon = 1.0e-25; 00017 static double hbar = 6.58211889e-25; // in GeV s 00018 double life, err; 00019 if( itsTotalWidth.value() < epsilon ) { 00020 // this should actually be infinity 00021 return Measurement( 0., 0.); 00022 } 00023 life = hbar / itsTotalWidth.value(); 00024 if( itsTotalWidth.sigma() < epsilon ) { 00025 err = 0.; 00026 } else { 00027 err = ( itsTotalWidth.sigma()/ itsTotalWidth.value() ) * life; 00028 } 00029 return Measurement( life, err ); 00030 } 00031 00032 } // HepPDT