* * $Id$ * * $Log$ * Revision 1.1 2000/06/19 20:00:30 eugenio * Initial revision * * Revision 1.1.1.1 1994/11/22 16:57:03 zfiles * first version of korb in CVS * * #include "sys/CLEO_machine.h" #include "pilot.h" *CMZ : 2.00/00 21/01/93 15.42.34 by Alan Weinstein *-- Author : SUBROUTINE DAMPAA(PT,PN,PIM1,PIM2,PIPL,AMPLIT,HV) C ---------------------------------------------------------------------- * CALCULATES DIFFERENTIAL CROSS SECTION AND POLARIMETER VECTOR * FOR TAU DECAY INTO A1, A1 DECAYS NEXT INTO RHO+PI AND RHO INTO PI+PI. * ALL SPIN EFFECTS IN THE FULL DECAY CHAIN ARE TAKEN INTO ACCOUNT. * CALCULATIONS DONE IN TAU REST FRAME WITH Z-AXIS ALONG NEUTRINO MOMENT * THE ROUTINE IS WRITEN FOR ZERO NEUTRINO MASS. C C called by : DPHSAA C ---------------------------------------------------------------------- COMMON / PARMAS / AMTAU,AMNUTA,AMEL,AMNUE,AMMU,AMNUMU * ,AMPIZ,AMPI,AMRO,GAMRO,AMA1,GAMA1 * ,AMK,AMKZ,AMKST,GAMKST C REAL*4 AMTAU,AMNUTA,AMEL,AMNUE,AMMU,AMNUMU * ,AMPIZ,AMPI,AMRO,GAMRO,AMA1,GAMA1 * ,AMK,AMKZ,AMKST,GAMKST COMMON / DECPAR / GFERMI,GV,GA,CCABIB,SCABIB,GAMEL REAL*4 GFERMI,GV,GA,CCABIB,SCABIB,GAMEL COMMON /TESTA1/ KEYA1 REAL HV(4),PT(4),PN(4),PIM1(4),PIM2(4),PIPL(4) REAL PAA(4),VEC1(4),VEC2(4) REAL PIVEC(4),PIAKS(4),HVM(4) COMPLEX BWIGN,HADCUR(4),FPIK DATA ICONT /1/ C * F CONSTANTS FOR A1, A1-RHO-PI, AND RHO-PI-PI * DATA FPI /93.3E-3/ * THIS INLINE FUNCT. CALCULATES THE SCALAR PART OF THE PROPAGATOR BWIGN(XM,AM,GAMMA)=1./CMPLX(XM**2-AM**2,GAMMA*AM) C * FOUR MOMENTUM OF A1 DO 10 I=1,4 10 PAA(I)=PIM1(I)+PIM2(I)+PIPL(I) * MASSES OF A1, AND OF TWO PI-PAIRS WHICH MAY FORM RHO XMAA =SQRT(ABS(PAA(4)**2-PAA(3)**2-PAA(2)**2-PAA(1)**2)) XMRO1 =SQRT(ABS((PIPL(4)+PIM1(4))**2-(PIPL(1)+PIM1(1))**2 $ -(PIPL(2)+PIM1(2))**2-(PIPL(3)+PIM1(3))**2)) XMRO2 =SQRT(ABS((PIPL(4)+PIM2(4))**2-(PIPL(1)+PIM2(1))**2 $ -(PIPL(2)+PIM2(2))**2-(PIPL(3)+PIM2(3))**2)) * ELEMENTS OF HADRON CURRENT PROD1 =PAA(4)*(PIM1(4)-PIPL(4))-PAA(1)*(PIM1(1)-PIPL(1)) $ -PAA(2)*(PIM1(2)-PIPL(2))-PAA(3)*(PIM1(3)-PIPL(3)) PROD2 =PAA(4)*(PIM2(4)-PIPL(4))-PAA(1)*(PIM2(1)-PIPL(1)) $ -PAA(2)*(PIM2(2)-PIPL(2))-PAA(3)*(PIM2(3)-PIPL(3)) DO 40 I=1,4 VEC1(I)= PIM1(I)-PIPL(I) -PAA(I)*PROD1/XMAA**2 40 VEC2(I)= PIM2(I)-PIPL(I) -PAA(I)*PROD2/XMAA**2 * HADRON CURRENT SATURATED WITH A1 AND RHO RESONANCES IF (KEYA1.EQ.1) THEN FA1=9.87 FAROPI=1.0 FRO2PI=1.0 FNORM=FA1/SQRT(2.)*FAROPI*FRO2PI DO 45 I=1,4 HADCUR(I)= CMPLX(FNORM) *AMA1**2*BWIGN(XMAA,AMA1,GAMA1) $ *(CMPLX(VEC1(I))*AMRO**2*BWIGN(XMRO1,AMRO,GAMRO) $ +CMPLX(VEC2(I))*AMRO**2*BWIGN(XMRO2,AMRO,GAMRO)) 45 CONTINUE ELSE FNORM=2.0*SQRT(2.)/3.0/FPI GAMAX=GAMA1*GFUN(XMAA**2)/GFUN(AMA1**2) DO 46 I=1,4 HADCUR(I)= CMPLX(FNORM) *AMA1**2*BWIGN(XMAA,AMA1,GAMAX) $ *(CMPLX(VEC1(I))*FPIK(XMRO1) $ +CMPLX(VEC2(I))*FPIK(XMRO2)) 46 CONTINUE ENDIF C * CALCULATE PI-VECTORS: VECTOR AND AXIAL CALL CLVEC(HADCUR,PN,PIVEC) CALL CLAXI(HADCUR,PN,PIAKS) CALL CLNUT(HADCUR,BRAKM,HVM) * SPIN INDEPENDENT PART OF DECAY DIFF-CROSS-SECT. IN TAU REST FRAME BRAK= (GV**2+GA**2)*PT(4)*PIVEC(4) +2.*GV*GA*PT(4)*PIAKS(4) & +2.*(GV**2-GA**2)*AMNUTA*AMTAU*BRAKM AMPLIT=(GFERMI*CCABIB)**2*BRAK/2. C THE STATISTICAL FACTOR FOR IDENTICAL PI'S WAS CANCELLED WITH C TWO, FOR TWO MODES OF A1 DECAY NAMELLY PI+PI-PI- AND PI-PI0PI0 C POLARIMETER VECTOR IN TAU REST FRAME DO 90 I=1,3 HV(I)=-(AMTAU*((GV**2+GA**2)*PIAKS(I)+2.*GV*GA*PIVEC(I))) & +(GV**2-GA**2)*AMNUTA*AMTAU*HVM(I) C HV IS DEFINED FOR TAU- WITH GAMMA=B+HV*POL HV(I)=-HV(I)/BRAK 90 CONTINUE END