d6/d62/pyhixtot_8f_source.html

C*********************************************************************


      SUBROUTINE pyhixtot


C...Parametrizes total, double diffractive, single diffractive and

C...elastic cross-sections for different energies and beams.

      common/ludat1/mstu(200),paru(200),mstj(200),parj(200)

      SAVE /ludat1/

      common/pyhipars/mstp(200),parp(200),msti(200),pari(200)

      SAVE /pyhipars/

      common/pyhiint1/mint(400),vint(400)

      SAVE /pyhiint1/

      common/pyhiint5/ngen(0:200,3),xsec(0:200,3)

      SAVE /pyhiint5/

      dimension bcs(5,8),bcb(2,5),bcc(3)


C...The following data lines are coefficients needed in the

C...Block, Cahn parametrization of total cross-section and nuclear

C...slope parameter; see below.

      DATA ((bcs(i,j),j=1,8),i=1,5)/

     1 41.74, 0.66, 0.0000, 337.,  0.0, 0.0, -39.3, 0.48,

     2 41.66, 0.60, 0.0000, 306.,  0.0, 0.0, -34.6, 0.51,

     3 41.36, 0.63, 0.0000, 299.,  7.3, 0.5, -40.4, 0.47,

     4 41.68, 0.63, 0.0083, 330.,  0.0, 0.0, -39.0, 0.48,

     5 41.13, 0.59, 0.0074, 278., 10.5, 0.5, -41.2, 0.46/

      DATA ((bcb(i,j),j=1,5),i=1,2)/

     1 10.79, -0.049, 0.040, 21.5, 1.23,

     2  9.92, -0.027, 0.013, 18.9, 1.07/

      DATA bcc/2.0164346,-0.5590311,0.0376279/


C...Total cross-section and nuclear slope parameter for pp and p-pbar

      nfit=min(5,max(1,mstp(31)))

      sigp=bcs(nfit,1)+bcs(nfit,2)*(-0.25*paru(1)**2*

     &(1.-0.25*bcs(nfit,3)*paru(1)**2)+(1.+0.5*bcs(nfit,3)*paru(1)**2)*

     &(log(vint(2)/bcs(nfit,4)))**2+bcs(nfit,3)*

     &(log(vint(2)/bcs(nfit,4)))**4)/

     &((1.-0.25*bcs(nfit,3)*paru(1)**2)**2+2.*bcs(nfit,3)*

     &(1.+0.25*bcs(nfit,3)*paru(1)**2)*(log(vint(2)/bcs(nfit,4)))**2+

     &bcs(nfit,3)**2*(log(vint(2)/bcs(nfit,4)))**4)+bcs(nfit,5)*

     &vint(2)**(bcs(nfit,6)-1.)*sin(0.5*paru(1)*bcs(nfit,6))

      sigm=-bcs(nfit,7)*vint(2)**(bcs(nfit,8)-1.)*

     &cos(0.5*paru(1)*bcs(nfit,8))

      refp=bcs(nfit,2)*paru(1)*log(vint(2)/bcs(nfit,4))/

     &((1.-0.25*bcs(nfit,3)*paru(1)**2)**2+2.*bcs(nfit,3)*

     &(1.+0.25*bcs(nfit,3)*paru(1)**2)+(log(vint(2)/bcs(nfit,4)))**2+

     &bcs(nfit,3)**2*(log(vint(2)/bcs(nfit,4)))**4)-bcs(nfit,5)*

     &vint(2)**(bcs(nfit,6)-1.)*cos(0.5*paru(1)*bcs(nfit,6))

      refm=-bcs(nfit,7)*vint(2)**(bcs(nfit,8)-1.)*

     &sin(0.5*paru(1)*bcs(nfit,8))

      sigma=sigp-isign(1,mint(11)*mint(12))*sigm

      rho=(refp-isign(1,mint(11)*mint(12))*refm)/sigma


C...Nuclear slope parameter B, curvature C:

      nfit=1

      IF(mstp(31).GE.4) nfit=2

      bp=bcb(nfit,1)+bcb(nfit,2)*log(vint(2))+

     &bcb(nfit,3)*(log(vint(2)))**2

      bm=bcb(nfit,4)+bcb(nfit,5)*log(vint(2))

      b=bp-isign(1,mint(11)*mint(12))*sigm/sigp*(bm-bp)

      vint(121)=b

      c=-0.5*bcc(2)/bcc(3)*(1.-sqrt(max(0.,1.+4.*bcc(3)/bcc(2)**2*

     &(1.e-03*vint(1)-bcc(1)))))

      vint(122)=c


C...Elastic scattering cross-section (fixed by sigma-tot, rho and B).

      sigel=sigma**2*(1.+rho**2)/(16.*paru(1)*paru(5)*b)


C...Single diffractive scattering cross-section from Goulianos:

      sigsd=2.*0.68*(1.+36./vint(2))*log(0.6+0.1*vint(2))


C...Double diffractive scattering cross-section (essentially fixed by

C...sigma-sd and sigma-el).

      sigdd=sigsd**2/(3.*sigel)


C...Total non-elastic, non-diffractive cross-section.

      signd=sigma-sigdd-sigsd-sigel


C...Rescale for pions.

      IF(iabs(mint(11)).EQ.211.AND.iabs(mint(12)).EQ.211) THEN

        sigma=4./9.*sigma

        sigdd=4./9.*sigdd

        sigsd=4./9.*sigsd

        sigel=4./9.*sigel

        signd=4./9.*signd

      ELSEIF(iabs(mint(11)).EQ.211.OR.iabs(mint(12)).EQ.211) THEN

        sigma=2./3.*sigma

        sigdd=2./3.*sigdd

        sigsd=2./3.*sigsd

        sigel=2./3.*sigel

        signd=2./3.*signd

      ENDIF


C...Save cross-sections in common block PYPARA.

      vint(101)=sigma

      vint(102)=sigel

      vint(103)=sigsd

      vint(104)=sigdd

      vint(106)=signd

      xsec(95,1)=signd


      RETURN

      END