2 C **********************************************************
3 C library of functions used in calculation of currents
5 C [1] arXiv:0911.4436 (hep-ph) D. Gomez Dumm et al. (tau -> 3pi nu)
6 C [2] arXiv:0911.2640 (hep-ph) D. Gomezz Dumm et al. (tau -> KKpi nu)
7 C [3] arXiv:0807.4883 (hep-ph) D. R. Boito et al. (tau -> Kpi nu)
8 C [4] P. Roig, talk at (tau -> 2 pi nu)
9 C [5] arXiv:0803.2039 (hep-ph) E. Arganda et al., Appendix B (tau -> KK nu)
10 C **********************************************************
11 FUNCTION GRHO_RCHT(XS,XMMM)
15 C **********************************************************
16 C REAL FUNCTION Gamma Rho ; energy-dependent width of rho meson
17 c in SU(2) limit mpi=mpi0, mk=mk0;
18 C formula (14) of REF [1]
19 C **********************************************************
20 include '../parameter.inc'
21 include '../funct_declar.inc'
28 IF(XS.GE.(4.*MMK_2)) THEN
29 GRHO_RCHT=XMMM*XS*((1.-4.*MMPI_AV2/XS)**1.5
30 $ +0.5*(1.-4.*MMK_2/XS)**1.5)
31 $ /(96.*PI*FPI_RPT**2)
32 ELSE IF((XS.GE.(4.*MMPI_AV2)).AND.(XS.LE.(4.*MMK_2))) THEN
33 GRHO_RCHT=XMMM*XS*(1.-4.*MMPI_AV2/XS)**1.5
34 $ /(96.*PI*FPI_RPT**2)
44 FUNCTION GRHO1_RCHT(XS,XMMM,XGGG)
47 DOUBLE PRECISION XMMM,XGGG
48 C **********************************************************
49 C REAL FUNCTION Gamma Rho1 ; energy-dependent width of rho1 meson;
50 c in SU(2) limit mpi=mpi0; only rho' -> 2pi loop;
51 C formula (33) of REF [1]
52 C **********************************************************
53 include '../parameter.inc'
54 include '../funct_declar.inc'
59 IF (XS.GE.(4.*MMPI_AV2)) THEN
60 GRHO1_RCHT=XGGG*SQRT(XMMM**2/XS)*
61 & ((XS-4.*MMPI_AV2)/(XMMM**2-4.*MMPI_AV2))**1.5
74 C***********************************************************
75 C DOUBLRE PRECISION FUNCTION
76 c of two body phase space threshold: equal mass scalars
77 C***********************************************************
79 include '../parameter.inc'
80 include '../funct_declar.inc'
82 TT = 1. - 4.*MMPI_AV**2/SS
96 FUNCTION LAMB_RCHT(X1,X2,X3)
98 REAL X1,X2,X3,ARG_RCHT
99 C***********************************************************
100 C REAL FUNCTION LAMDA of three body phase space
101 C***********************************************************
102 include '../funct_declar.inc'
104 ARG_RCHT = (X1-X2-X3)**2 - 4.*X3*X2
105 IF(ARG_RCHT.GE.0.) THEN
116 C******************** FUNCTIONS FOR 2 SCALAR MODES ***********************
120 C****************************************************************
121 FUNCTION R0SCAL_3PI(QX,SX)
122 C****************************************************************
123 C Complex Function: R_0 function (Pablo notes)
124 C for the scalar contribution for three pion modes
125 C Called by f3pi_rcht.f
126 C **********************************************************
128 REAL QX,SX,delta0_3piscal,xsx,xst
129 DOUBLE PRECISION XM1,XM2,DSX
130 include '../funct_declar.inc'
131 include '../parameter.inc'
132 c$$$ a00_3piscal = 0.220
133 c$$$ b00_3piscal = 0.268/mmpi_av**2
134 c$$$ c00_3piscal = -0.0139/mmpi_av**4
135 c$$$ d00_3piscal = -0.00139/mmpi_av**6
136 c$$$ x00_3piscal = 36.77*mmpi_av**2
140 xsx = sx/4.*sigp(dsx)**2
144 delta0_3piscal = sigp(dsx)*(a00_3piscal + b00_3piscal*xsx +
145 & c00_3piscal*xsx**2 + d00_3piscal*xsx**3)
147 delta0_3piscal = delta0_3piscal*
148 & (4*mmpi_av**2 - x00_3piscal)/(sx-x00_3piscal)
149 else if (xst.le.1.21) then
150 delta0_3piscal = -10572.0+50658.0*xst-87903.0*xst**2+66886.0*xst**3
152 delta0_3piscal = delta0_3piscal*pi/180.0
154 delta0_3piscal = 255.0*pi/180.0
158 delta0_3piscal = atan(delta0_3piscal)
160 R0SCAL_3PI = ALPHA0_3PI/QX +
161 & ALPHA1_3PI/QX**2*(SX - MMF0**2)
163 R0SCAL_3PI = R0SCAL_3PI*(cos(delta0_3piscal) +
164 & i*sin(delta0_3piscal))
169 C****************************************************************
170 FUNCTION R2SCAL_3PI(QX,SX)
171 C****************************************************************
172 C Complex Function: R_2 function (Pablo notes)
173 C for the scalar contribution for three pion modes
174 C Called by f3pi_rcht.f
175 C **********************************************************
177 REAL QX,SX,delta2_3piscal,xsx,xst
178 DOUBLE PRECISION XM1,XM2,DSX
179 include '../funct_declar.inc'
180 include '../parameter.inc'
181 c$$$ a02_3piscal = -0.0444
182 c$$$ b02_3piscal = -0.0857/mmpi_av**2
183 c$$$ c02_3piscal = -0.00221/mmpi_av**4
184 c$$$ d02_3piscal = -0.000129/mmpi_av**6
185 c$$$ x02_3piscal = -21.62*mmpi_av**2
189 xsx = sx/4.*sigp(dsx)**2
193 delta2_3piscal = sigp(dsx)*(a02_3piscal + b02_3piscal*xsx +
194 & c02_3piscal*xsx**2 + d02_3piscal*xsx**3)
196 delta2_3piscal = delta2_3piscal*
197 & (4*mmpi_av**2 - x02_3piscal)/(sx-x02_3piscal)
198 else if(xst.le.1.21) then
199 delta2_3piscal = 282.9-1314.9*xst+2153.4*xst**2-1574.5d0*xst**3+
201 delta2_3piscal = delta2_3piscal*pi/180.0
203 delta2_3piscal = -27.0*pi/180.0
206 delta2_3piscal = atan(delta2_3piscal)
208 R2SCAL_3PI = GAMMA0_3PI/QX +
209 & GAMMA1_3PI/QX**2*(SX - MMF0**2)
211 R2SCAL_3PI = R2SCAL_3PI*(cos(delta2_3piscal) +
212 & i*sin(delta2_3piscal))
220 C*************************************************************************
221 C Functions for sigma contributions
222 C*************************************************************************
223 FUNCTION FFsig(QX,XX)
224 C **********************************************************
226 C Called by f3pi_rcht.f
227 C **********************************************************
230 DOUBLE PRECISION XM1,XM2,xphi
231 include '../funct_declar.inc'
232 include '../parameter.inc'
236 xphi = - rsigma**2* LAMB_RCHT(QX,XX,mm2)/(8.*QX)
246 C*************************************************************************
247 FUNCTION BWsig(XM,XG,XQ)
248 C **********************************************************
249 C Complex Function: S-wave Breit-Wigner
250 C Called by f3pi_rcht.f
251 C **********************************************************
254 DOUBLE PRECISION XM,XG,XM2,XXQ,GAMMA
255 include '../funct_declar.inc'
256 include '../parameter.inc'
260 GAMMA = XG*SIGP(XXQ)/SIGP(XM2)
261 BWsig = XM*XM/CMPLX(XM*XM-XQ, -XM*GAMMA)
267 C*************************************************************************
268 FUNCTION DECOUL(mm1,mm3,ss2)
269 C **********************************************************
270 C Real Function: Coulomb interaction effects of two particles
272 C Called by f3pi_rcht.f
273 C **********************************************************
276 DOUBLE PRECISION mm1,mm3,betam1m3
278 include '../funct_declar.inc'
279 include '../parameter.inc'
280 C*******************************************
281 C COMMON block fixed in SUBROUTINE INIPHY
282 c*******************************************
283 COMMON / QEDPRM /ALFINV,ALFPI,XK0
284 REAL*8 ALFINV,ALFPI,XK0
285 betam1m3 = 1.d0 - (mm1 +mm3)**2/ss2
286 betam1m3 = dsqrt(betam1m3)
288 if(ss2.gt.(mm1+mm3)**2)
289 & decoul = pi/2.d0/betam1m3/ALFINV
294 C*************************************************************************
295 FUNCTION COUL3PART(mm1,mm2,mm3,ss1,ss2,ss3)
296 C **********************************************************
297 C Real Function: Coulomb interaction effects of two particles
299 C Called by f3pi_rcht.f
300 C **********************************************************
303 DOUBLE PRECISION mm1,mm2,mm3
304 include '../funct_declar.inc'
305 include '../parameter.inc'
307 coul3part = decoul(mm1,mm3,ss2) + decoul(mm2,mm3,ss1)
308 & - decoul(mm1,mm2,ss3)
310 coul3part = exp(coul3part)
314 C*************************************************************************
315 FUNCTION fattcoul(mm1,mm3,ss2)
316 C **********************************************************
317 C Real Function: Coulomb attraction of two particles
319 C Called by f3pi_rcht.f
320 C **********************************************************
323 DOUBLE PRECISION mm1,mm3,betam1m3
325 include '../funct_declar.inc'
326 include '../parameter.inc'
327 C*******************************************
328 C COMMON block fixed in SUBROUTINE INIPHY
329 c*******************************************
330 COMMON / QEDPRM /ALFINV,ALFPI,XK0
331 REAL*8 ALFINV,ALFPI,XK0
332 if(ss2.gt.(mm1+mm3)**2) then
333 betam1m3 = 2.*dsqrt(1.d0 - (mm1 +mm3)**2/ss2)
334 & /(1.+ (1.d0 - (mm1 +mm3)**2/ss2))
337 fattcoul = 2.*pi/betam1m3/ALFINV
338 & /(1.-exp(-2.*pi/betam1m3/ALFINV))
346 C*************************************************************************
347 C*************************************************************************
348 FUNCTION frepcoul(mm1,mm3,ss2)
349 C **********************************************************
350 C Real Function: Coulomb repuslcion of two particles
352 C Called by f3pi_rcht.f
353 C **********************************************************
356 DOUBLE PRECISION mm1,mm3,betam1m3
358 include '../funct_declar.inc'
359 include '../parameter.inc'
360 C*******************************************
361 C COMMON block fixed in SUBROUTINE INIPHY
362 c*******************************************
363 COMMON / QEDPRM /ALFINV,ALFPI,XK0
364 REAL*8 ALFINV,ALFPI,XK0
365 if(ss2.gt.(mm1+mm3)**2) then
366 betam1m3 = 2.*dsqrt(1.d0 - (mm1 +mm3)**2/ss2)
367 & /(1.+ (1.d0 - (mm1 +mm3)**2/ss2))
369 frepcoul = 2.*pi/betam1m3/ALFINV
370 & /(-1.+exp(2.*pi/betam1m3/ALFINV))
377 C*************************************************************************