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Commit | Line | Data |
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da0e9ce3 | 1 | SUBROUTINE PHOENE(MPASQR,MCHREN,BETA,IDENT) |
2 | C.---------------------------------------------------------------------- | |
3 | C. | |
4 | C. PHOTOS: PHOton radiation in decays calculation of photon ENErgy | |
5 | C. fraction | |
6 | C. | |
7 | C. Purpose: Subroutine returns photon energy fraction (in (parent | |
8 | C. mass)/2 units) for the decay bremsstrahlung. | |
9 | C. | |
10 | C. Input Parameters: MPASQR: Mass of decaying system squared, | |
11 | C. XPHCUT: Minimum energy fraction of photon, | |
12 | C. XPHMAX: Maximum energy fraction of photon. | |
13 | C. | |
14 | C. Output Parameter: MCHREN: Renormalised mass squared, | |
15 | C. BETA: Beta factor due to renormalisation, | |
16 | C. XPHOTO: Photon energy fraction, | |
17 | C. XF: Correction factor for PHOFAC. | |
18 | C. | |
19 | C. Author(s): S. Jadach, Z. Was Created at: 01/01/89 | |
20 | C. B. van Eijk Last Update: 26/03/93 | |
21 | C. | |
22 | C.---------------------------------------------------------------------- | |
23 | IMPLICIT NONE | |
24 | DOUBLE PRECISION MPASQR,MCHREN,BIGLOG,BETA,DATA | |
25 | INTEGER IWT1,IRN,IWT2 | |
26 | REAL*8 PRSOFT,PRHARD,PHORAN,PHOFAC | |
27 | DOUBLE PRECISION MCHSQR,MNESQR | |
28 | REAL*8 PNEUTR | |
29 | INTEGER IDENT | |
30 | REAL*8 PHOCHA | |
31 | COMMON/PHOMOM/MCHSQR,MNESQR,PNEUTR(5) | |
32 | DOUBLE PRECISION COSTHG,SINTHG | |
33 | REAL*8 XPHMAX,XPHOTO | |
34 | COMMON/PHOPHS/XPHMAX,XPHOTO,COSTHG,SINTHG | |
35 | REAL*8 ALPHA,XPHCUT | |
36 | COMMON/PHOCOP/ALPHA,XPHCUT | |
37 | REAL*8 PI,TWOPI | |
38 | COMMON/PHPICO/PI,TWOPI | |
39 | INTEGER IREP | |
40 | REAL*8 PROBH,CORWT,XF | |
41 | COMMON/PHOPRO/PROBH,CORWT,XF,IREP | |
42 | LOGICAL INTERF,ISEC,IFTOP | |
43 | REAL*8 FINT,FSEC | |
44 | COMMON /PHOKEY/ FSEC,FINT,INTERF,ISEC,IFTOP | |
45 | C-- | |
46 | IF (XPHMAX.LE.XPHCUT) THEN | |
47 | XPHOTO=0.0D0 | |
48 | RETURN | |
49 | ENDIF | |
50 | C-- Probabilities for hard and soft bremstrahlung... | |
51 | MCHREN=4.D0*MCHSQR/MPASQR/(1.D0+MCHSQR/MPASQR)**2 | |
52 | BETA=SQRT(1.D0-MCHREN) | |
53 | BIGLOG=LOG(MPASQR/MCHSQR*(1.D0+BETA)**2/4.D0* | |
54 | & (1.D0+MCHSQR/MPASQR)**2) | |
55 | PRHARD=ALPHA/PI/BETA*BIGLOG*(LOG(XPHMAX/XPHCUT)-.75D0+XPHCUT/ | |
56 | &XPHMAX-.25D0*XPHCUT**2/XPHMAX**2) | |
57 | PRHARD=PRHARD*PHOCHA(IDENT)**2*FINT*FSEC | |
58 | IF (IREP.EQ.0) PROBH=0.D0 | |
59 | PRHARD=PRHARD*PHOFAC(0) | |
60 | PROBH=PRHARD | |
61 | PRSOFT=1.D0-PRHARD | |
62 | C-- | |
63 | C-- Check on kinematical bounds | |
64 | IF (PRSOFT.LT.0.1D0) THEN | |
65 | DATA=PRSOFT | |
66 | CALL PHOERR(2,'PHOENE',DATA) | |
67 | ENDIF | |
68 | IF (PHORAN(IWT1).LT.PRSOFT) THEN | |
69 | C-- | |
70 | C-- No photon... (ie. photon too soft) | |
71 | XPHOTO=0.D0 | |
72 | ELSE | |
73 | C-- | |
74 | C-- Hard photon... (ie. photon hard enough). | |
75 | C-- Calculate Altarelli-Parisi Kernel | |
76 | 10 XPHOTO=EXP(PHORAN(IRN)*LOG(XPHCUT/XPHMAX)) | |
77 | XPHOTO=XPHOTO*XPHMAX | |
78 | IF (PHORAN(IWT2).GT.((1.D0+(1.D0-XPHOTO/XPHMAX)**2)/2.D0)) | |
79 | & GOTO 10 | |
80 | ENDIF | |
81 | C-- | |
82 | C-- Calculate parameter for PHOFAC function | |
83 | XF=4.D0*MCHSQR*MPASQR/(MPASQR+MCHSQR-MNESQR)**2 | |
84 | RETURN | |
85 | END |