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src/EvtGenModels/EvtVubHybrid.cpp
| Show First 20 Lines • Show All 269 Lines • ▼ Show 20 Lines | void EvtVubHybrid::decay( EvtParticle* p ) | ||||
| // now compute the four vectors in the B Meson restframe | // now compute the four vectors in the B Meson restframe | ||||
| double ptmp, sttmp; | double ptmp, sttmp; | ||||
| // calculate the hadron 4 vector in the B Meson restframe | // calculate the hadron 4 vector in the B Meson restframe | ||||
| sttmp = sqrt( 1 - ctH * ctH ); | sttmp = sqrt( 1 - ctH * ctH ); | ||||
| ptmp = sqrt( Eh * Eh - sh ); | ptmp = sqrt( Eh * Eh - sh ); | ||||
| double pHB[4] = {Eh, ptmp * sttmp * cos( phH ), ptmp * sttmp * sin( phH ), | double pHB[4] = { Eh, ptmp * sttmp * cos( phH ), ptmp * sttmp * sin( phH ), | ||||
| ptmp * ctH}; | ptmp * ctH }; | ||||
| p4.set( pHB[0], pHB[1], pHB[2], pHB[3] ); | p4.set( pHB[0], pHB[1], pHB[2], pHB[3] ); | ||||
| xuhad->init( getDaug( 0 ), p4 ); | xuhad->init( getDaug( 0 ), p4 ); | ||||
| if ( _storeQplus ) { | if ( _storeQplus ) { | ||||
| // cludge to store the hidden parameter q+ with the decay; | // cludge to store the hidden parameter q+ with the decay; | ||||
| // the lifetime of the Xu is abused for this purpose. | // the lifetime of the Xu is abused for this purpose. | ||||
| // tau = 1 ps corresponds to ctau = 0.3 mm -> in order to | // tau = 1 ps corresponds to ctau = 0.3 mm -> in order to | ||||
| // stay well below BaBars sensitivity we take q+/(10000 GeV) which | // stay well below BaBars sensitivity we take q+/(10000 GeV) which | ||||
| // goes up to 0.0005 in the most extreme cases as ctau in mm. | // goes up to 0.0005 in the most extreme cases as ctau in mm. | ||||
| // To extract q+ back from the StdHepTrk its necessary to get | // To extract q+ back from the StdHepTrk its necessary to get | ||||
| // delta_ctau = Xu->anyDaughter->getVertexTime()-Xu->getVertexTime() | // delta_ctau = Xu->anyDaughter->getVertexTime()-Xu->getVertexTime() | ||||
| // where these pseudo calls refere to the StdHep time stored at | // where these pseudo calls refere to the StdHep time stored at | ||||
| // the production vertex in the lab for each particle. The boost | // the production vertex in the lab for each particle. The boost | ||||
| // has to be reversed and the result is: | // has to be reversed and the result is: | ||||
| // | // | ||||
| // q+ = delta_ctau * 10000 GeV/mm * Mass_Xu/Energy_Xu | // q+ = delta_ctau * 10000 GeV/mm * Mass_Xu/Energy_Xu | ||||
| // | // | ||||
| xuhad->setLifetime( qplus / 10000. ); | xuhad->setLifetime( qplus / 10000. ); | ||||
| } | } | ||||
| // calculate the W 4 vector in the B Meson restrframe | // calculate the W 4 vector in the B Meson restrframe | ||||
| double apWB = ptmp; | double apWB = ptmp; | ||||
| double pWB[4] = {mB - Eh, -pHB[1], -pHB[2], -pHB[3]}; | double pWB[4] = { mB - Eh, -pHB[1], -pHB[2], -pHB[3] }; | ||||
| // first go in the W restframe and calculate the lepton and | // first go in the W restframe and calculate the lepton and | ||||
| // the neutrino in the W frame | // the neutrino in the W frame | ||||
| double mW2 = mB * mB + sh - 2 * mB * Eh; | double mW2 = mB * mB + sh - 2 * mB * Eh; | ||||
| double beta = ptmp / pWB[0]; | double beta = ptmp / pWB[0]; | ||||
| double gamma = pWB[0] / sqrt( mW2 ); | double gamma = pWB[0] / sqrt( mW2 ); | ||||
| double pLW[4]; | double pLW[4]; | ||||
| ptmp = ( mW2 - ml * ml ) / 2 / sqrt( mW2 ); | ptmp = ( mW2 - ml * ml ) / 2 / sqrt( mW2 ); | ||||
| pLW[0] = sqrt( ml * ml + ptmp * ptmp ); | pLW[0] = sqrt( ml * ml + ptmp * ptmp ); | ||||
| double ctL = ( El - gamma * pLW[0] ) / beta / gamma / ptmp; | double ctL = ( El - gamma * pLW[0] ) / beta / gamma / ptmp; | ||||
| if ( ctL < -1 ) | if ( ctL < -1 ) | ||||
| ctL = -1; | ctL = -1; | ||||
| if ( ctL > 1 ) | if ( ctL > 1 ) | ||||
| ctL = 1; | ctL = 1; | ||||
| sttmp = sqrt( 1 - ctL * ctL ); | sttmp = sqrt( 1 - ctL * ctL ); | ||||
| // eX' = eZ x eW | // eX' = eZ x eW | ||||
| double xW[3] = {-pWB[2], pWB[1], 0}; | double xW[3] = { -pWB[2], pWB[1], 0 }; | ||||
| // eZ' = eW | // eZ' = eW | ||||
| double zW[3] = {pWB[1] / apWB, pWB[2] / apWB, pWB[3] / apWB}; | double zW[3] = { pWB[1] / apWB, pWB[2] / apWB, pWB[3] / apWB }; | ||||
| double lx = sqrt( xW[0] * xW[0] + xW[1] * xW[1] ); | double lx = sqrt( xW[0] * xW[0] + xW[1] * xW[1] ); | ||||
| for ( j = 0; j < 2; j++ ) | for ( j = 0; j < 2; j++ ) | ||||
| xW[j] /= lx; | xW[j] /= lx; | ||||
| // eY' = eZ' x eX' | // eY' = eZ' x eX' | ||||
| double yW[3] = {-pWB[1] * pWB[3], -pWB[2] * pWB[3], | double yW[3] = { -pWB[1] * pWB[3], -pWB[2] * pWB[3], | ||||
| pWB[1] * pWB[1] + pWB[2] * pWB[2]}; | pWB[1] * pWB[1] + pWB[2] * pWB[2] }; | ||||
| double ly = sqrt( yW[0] * yW[0] + yW[1] * yW[1] + yW[2] * yW[2] ); | double ly = sqrt( yW[0] * yW[0] + yW[1] * yW[1] + yW[2] * yW[2] ); | ||||
| for ( j = 0; j < 3; j++ ) | for ( j = 0; j < 3; j++ ) | ||||
| yW[j] /= ly; | yW[j] /= ly; | ||||
| // p_lep = |p_lep| * ( sin(Theta) * cos(Phi) * eX' | // p_lep = |p_lep| * ( sin(Theta) * cos(Phi) * eX' | ||||
| // + sin(Theta) * sin(Phi) * eY' | // + sin(Theta) * sin(Phi) * eY' | ||||
| // + cos(Theta) * eZ') | // + cos(Theta) * eZ') | ||||
| for ( j = 0; j < 3; j++ ) | for ( j = 0; j < 3; j++ ) | ||||
| Show All 11 Lines | void EvtVubHybrid::decay( EvtParticle* p ) | ||||
| ptmp = sqrt( El * El - ml * ml ); | ptmp = sqrt( El * El - ml * ml ); | ||||
| double ctLL = appLB / ptmp; | double ctLL = appLB / ptmp; | ||||
| if ( ctLL > 1 ) | if ( ctLL > 1 ) | ||||
| ctLL = 1; | ctLL = 1; | ||||
| if ( ctLL < -1 ) | if ( ctLL < -1 ) | ||||
| ctLL = -1; | ctLL = -1; | ||||
| double pLB[4] = {El, 0, 0, 0}; | double pLB[4] = { El, 0, 0, 0 }; | ||||
| double pNB[4] = {pWB[0] - El, 0, 0, 0}; | double pNB[4] = { pWB[0] - El, 0, 0, 0 }; | ||||
| for ( j = 1; j < 4; j++ ) { | for ( j = 1; j < 4; j++ ) { | ||||
| pLB[j] = pLW[j] + ( ctLL * ptmp - ctL * apLW ) / apWB * pWB[j]; | pLB[j] = pLW[j] + ( ctLL * ptmp - ctL * apLW ) / apWB * pWB[j]; | ||||
| pNB[j] = pWB[j] - pLB[j]; | pNB[j] = pWB[j] - pLB[j]; | ||||
| } | } | ||||
| p4.set( pLB[0], pLB[1], pLB[2], pLB[3] ); | p4.set( pLB[0], pLB[1], pLB[2], pLB[3] ); | ||||
| lepton->init( getDaug( 1 ), p4 ); | lepton->init( getDaug( 1 ), p4 ); | ||||
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