General information

Main Subroutines

Main Data Blocks

Event Options and Parameters

Example Program

History of Updates

Last modified on February 11, 1997 by Xin-Nian Wang

General Information

Main Subroutines (Go back to the main manual)

Purpose:

This subroutine is to initialize HIJING which should be called first before any subroutine.

EFRM(GeV):

is the colliding energy in the frame specified by FRAME.

FRAME: (must be 'LAB' or 'CMS')

to specify the frame of the collision

PROJ,TARG:

Character variables of proj and targ particles.

='P' proton

='PBAR' anti-proton

='N' neutron

='NBAR' anti-neutron

='PI+' positive pion

='PI-' negative pion

='K+' positive kaon

='K-' negative kaon

='A' nucleus

IAP,IAT:

mass number of the projectile and target nuclei, set to 1 for hadrons

IZP,IZT:

charge number of the projectile and target nuclei,for hadrons it is the charge of that hadron(=1,0,-1)

Purpose:

This is the main program of HIJING which can be called(many times) only after HIJSET is called once.

FRAME: (must be 'LAB' or 'CMS')

to specify the frame of the collision

BMIN,BMAX:

are the low and up limits bewteen which the impact parameters are randomly but evenly selected for pA and AA collisions. For pp collisions, the events are averaged over all impact parameters.

Main Data blocks (Go back to the main manual)

NATT:

total number of produced stable particles of the current event.

EATT:

the total c.m.s energy of the produced particles to check energy conservation.

JATT:

the total number of jet-pairs in the current event.

NT,NP:

number of wounded target and projetile nucleons.

N0,N01,N10,N11:

number of N-N,N-N_wounded,N_wounded-N, and N_wounded-N_wounded collisions in the current event.

KATT(I,1)(I=1,NATT):

partilce ID of the I_th produced particle. Users have to refer to JETSET7.2 for identifying particles with their ID's.(See the end of this documentation)

KATT(I,2)(I=1,NATT):

This is a code to identify the sources from which the particle comes.

=0 projectile which has not interacted at all

=1 projectile which only suffers an elastic collision

=2 from the diffractive projectile in a single diffractive interaction

=3 from the fragmentation of projectile strings

=10 target which has not interacted at all

=11 target which only suffers an elastic collision

=12 from the diffractive target in a single diffractive interaction

=13 from the fragmentation of target strings

=20 from hard scattered partons which form string systems themselves.

=30 from soft sea-quarks strings

=40 from direct production in the hard processes( currently,only direct photons are included).

KATT(I,3)(I=1,NATT):

The line number of the parent particle. For finally produced or directly produced (not from the decay of another particle) particles, it is set to 0 (The option to retain the information of all particles including the decayed ones is IHPR2(21)=1).

KATT(I,4)(I=1,NATT):

Status number of the particle:

=1 finally or directly produced particles.

=11 particles which has already decayed.

PATT(I,1:4)(I=1,NATT):

four-momentum of I_th produced particle.

COMMON/HIJJET1/NPJ(300),KFPJ(300,500),PJPX(300,500),PJPY(300,500)

,PJPZ(300,500),PJPE(300,500),PJPM(300,500)

,NTJ(300),KFTJ(300,500),PJTX(300,500),PJTY(300,500)

,PJTZ(300,500),PJTE(300,500),PJTM(300,500)

NPJ(I)(I=1,IAP):

number of partons associated with I_th projectile

KFPJ(I,J)(J=1,NPJ(I)):

parton ID of the J_th parton associated with I_th projectile.

PJPX(I,J),PJPY(I,J),PJPZ(I,J),PJPE(I,J),PJPM(I,J):

the four momentum and rest mass of J_th parton associated with the I_th projectile

NTJ(I)(I=1,IAT):

number of partons associated with I_th target

KFTJ(I,J)(J=1,NTJ(I)):

parton ID of the J_th parton associated with I_th target.

PJTX(I,J),PJTY(I,J),PJTZ(I,J),PJTE(I,J),PJTM(I,J):

the four momentum and rest mass of J_th parton associated with the I_th target.

COMMON/HIJJET2/NSG,NJSG(900),IASG(900,3),K1SG(900,100),K2SG(900,100)

,PXSG(900,100),PYSG(900,100),PZSG(900,100),PESG(900,100),PMSG(900,100)

NSG:

the total number of such string systems.

NJSG(I)(I=1,NSG):

number of partons in the I_th string system.

IASG(I,1),IASG(I,2):

specify which projetile and target produce the I_th string system

IASG(I,3):=0

the jets will be quenched 1 the jets will not be quenched

K1SG(I,J)(J=1,NJSG(I)):

color flow information of J_th parton in the I_th string system.

K2SG(I,J)(J=1,NJSG(I)):

ID code of J_th parton in I_th string.

PXSG(I,J),PYSG(I,J),PZSG(I,J),PESG(I,J),PMSG(I,J):

four momentum and rest mass of the J_th parton in the I_th string system.

NFP(K,1):flavor of quark in projectile.

NFP(K,2):flavor of diquark in projectile.

NFP(K,3):present particle ID of the projectile.

NFP(K,4):original particle ID of projectile.

NFP(K,5):collision status of projectile

=0:no collision;

=1:elastic;

=2:the diffractive one in a single-diffractive

=3:beccomes excited string after an inelastic

NFP(K,6):

is the total number of jet production associated with ths projectile. if NFP(K,6)<0 it can not produce jet anymore due to energy conservation.

NFP(K,10):

to indicate whether the valence quarks or diquarks has had a hard scattering,

=0: have no hard scattering;

=1,-1: has or had a hard scattering.

NFP(K,11):

total number of interactions this projectile has suffered so far.

PP(K,1),PP(K,2),PP(K,3),PP(K,4),PP(K,5):

four momentum and the invariant mass (Px,Py,Pz,E,M) of the projectile.

PP(K,6),PP(K,7):transverse momentum (Px,Py) of the quark.

PP(K,8),PP(K,9):transverse momentum (Px,Py) of the diquark.

PP(K,10),PP(K,11),PP(K,12):

three momentum (Px,Py,Pz) the quark or diquark has from the last hard scattering it suffered.

PP(K,14):the mass of the projectile quark.

PP(K,15):the mass of the projectile diquark.

NFT(K,1-15),PT(K,1-15):

are about the same information of target and target quarks, diquarks.

Event Options and Parameters (Go back to the main manual)

HIPR1(1):(D=1.5 GeV)

Minimum value for the invariant mass of the excited string system in a hadron-hadron interaction.

HIPR1(2):(D=0.35 GeV)

width of the Gaussian pt distribution of hadron in string fragmenation.

HIPR1(3),HIPR1(4):(D=0.5,0.9 GeV**-2)

give the a and b parameters of the symmetric LUND fragmentatin fuction.

HIPR1(5):(D=2.0)

cut-off for the QCD radiation, string system with invariant mass below it will not radiate soft gluons.

HIPR1(6):(D=0.1)

The shadowing of structure fucntion at x=0 is parametrized as HIPR1(6)*(A**(1/3)-1.0)

HIPR1(7):not used

HIPR1(8):(D=2.0 GeV) Minimum pt of hard or semihard scatterings.

HIPR1(9):(D=-1.0 GeV)

Maximum pt of hard or semihard scatterings, if negative there is no up-limit.

HIPR1(10):(D=-2.25 GeV)

To specify the value of PT for one hard scattering generated per event(we call them sample jets), which could be used to study jet in AA collision. If HIPR1(10) is negtive, its absolute value gives the low limit of the PT of the sample jets.

HIPR1(11):(D=2.0 GeV)

Minimum pt of a jet which will interact with excited nuclear matter, or when the pt of a jet is smaller than HIPR1(11) it will stop interacting further more.

HIPR1(12):(D=1.0 fm)

The transverse distance between a traversing jet and an excited nucleon(or string system) below which they will interact and the jet will lose energy and momentum to the nucleon.

HIPR1(13):(D=1.0 fm)

The mean free path of a jet to interact when it goes through an excited nuclear matter.

HIPR1(14):(D=2.0 GeV/fm)

The string tension of a gluon jet. It is the energy loss dE/dx=HIPR1(14) of the gluon jet when the string is streched. For quark jet dE/dx=0.5*HIPR1(14).

HIPR1(15):(D=0.2 GeV)

the momentum scale lamda in the calculation of alpha_strong.

HIPR1(16):(D=2.0 GeV)

The initial mometum scale Q0 for the evolution of the structure fuction.

HIPR1(17):(D=2.0)

K factor for the differential jet cross sections.

HIPR1(18):(D=0.2)

Fractional probability for color flip occuring to sea quarks among inelatic events in the DPM-like option.

HIPR1(19),HIPR1(20):(D=0.1,1.6 GeV)

The pt kick from the initial and final state interaction will follow 1/(HIPR1(19)**2+pt**2)/(HIPR1(20)**2+pt**2) distribution. HIPR1(19) regularizes the singularity at pt=0 and HIPR1(20) gives the scale beyond which the distribution will be like 1/pt**4.

HIPR1(21):(D=1.6 GeV)

The maximum pt for the pt kick per initial or final state interaction. Beyond this value the pt_kick-HIPR1(21) will follow the same Gaussion distribution given by HIPR1(2).

HIPR1(22):(D=2.0 GeV)

The form factor parameter to supress the diquarks from having a pt transfer relative to the quarks,1/(1+pt**2/HIPR1(22)**2).

HIPR1(23)-HIPR1(28):not used.

HIPR1(29):(D=0.4 fm)

the minimum distance between two nucleons inside a nucleus when the coordinates of all the nucleons in a nucleus are initialized.

HIPR1(30):(D=2*HIPR1(31)=57.0 bm)

the inclusive cross section sigma_s for soft interaction. The default value sigma_s=sigma_0 is used to insure the geometrical scaling of pp interaction cross section at low energies.

HIPR1(31):(D=28.5 bm)

the cross section sigam_0 which characterizes the geometrical size of a nucleon (HIPR1(31)=pi*b0**2). The default value is only for high-energy limite(sqrt{s}>200 GeV). At lower energies, a slight decrease which depends on energy is parametrized in the program. The default value of the above two parameters HIPR1(30),HIPR1(31) are only for NN type interactions. For other kinds of projectile or target hadrons users should change these values so that a correct inelastic and total cross section HINT1(12),HINT1(13) are obtained by the program.

HIPR1(32):(D=3.90)

The parameter in the scaled eikonal function of nucleon Xi(R)=A**2*(A*R)**3*K3(A*R),A=HIPR1(32) which is a Fourier transform of a dipole formtor 1/(1+Q**2/mu**2)**2 and A=mu*b0 and pi*b0**2=HIPR1(31).

HIPR1(33):

fractional cross section of single-diffractive interaction.(parametrized)

HIPR1(34):

Maximum radial coordinator for projectile nucleons to be given by the initialzation program HIJSET.

HIPR1(35):

Maximum radial coordinator for target nucleons to be given by the initialzation program HIJSET.

HIPR1(36)-HIPR1(39):not used

HIPR1(40):(D=3.141592654) value of pi.

HIPR1(41):not used

HIPR1(42):(D=0.4)

parameter in the expotnetial pt distribution of sea quarks production in DPM option

HIPR1(43):(D=0.01)

The fractional energy error relative to the colliding energy permitted per nucleon-nucleon collisions.

HIPR1(44),HIPR1(45),HIPR1(46):(D=1.5,0.1,0.25)

These parameters give the x distribution of valence quarks (1-x)**HIPR1(44)/(x**2+HIPR1(45)**2/s)**HIPR1(46) for baryons, and 1/(x**2+HIPR1(45)**2/s)**HIPR1(46)/ ((1-x)**2+HIPR1(45)**2/s)**HIPR(46) for mesons, in soft interactions.

HIPR1(47),HIPR1(48):(D=0.0,0.5)

These two parameters give x distribution of the sea quarks (1-x)**HIPR1(47)/(x**2+HIPR1(45)**2/s)**HIPR1(48), in a soft interaction. The same is used for the the distribution of the invariant mass of the disassociated nucleon in a single diffractive collision.

HIPR1(49)-HIPR1(100):not used.

IHPR2(1):(D=1)

switch for dipole-approximated QCD radiation of the string system in soft interaction.

IHPR2(2):(D=3)

switch for initial and final state radiation in the hard scattering.

=0: both initial and final radiation off;

=1: initial radiation on and final radiation off;

=2: initial radiation off and final radiation on;

=3: both initial and final radiation on.

IHPR2(3):(D=0)

switch for one hard scattering with specified PT PT=HIPR1(10) per event.

=1:ordinary hard processes;

=2:only direct photon production.

=3:heavy quark production (charm IHPR2(18)=0 or beauty IHPR2(18)=1). For inclusive production, one should reset HIPR1(10)=0.0. One can also trig larger pt QQbar production by giving HIPR1(10) a nonvanishing value. The mass of the heavy quark in the calculation of the cross section (HINT1(59)--HINT1(65)) is given by HIPR1(7) (the default is the charm mass D=1.5). We also include a separate K-factor for heavy quark and direct photon production by HIPR1(23)(D=2.0).

IHPR2(4):(D=1)

switch for jet quenching in the the exicited nuclear matter,i.e. jets only interact with those nuclear matter that has suffered collisions.

IHPR2(5):(D=1)

switch for the pt kick due to soft initial state interaction both for valence quarks or diquarks and gluons.

IHPR2(6):(D=1)

switch for the nuclear effect on the parton distribution function.

IHPR2(7):(D=1)(1 or 2)

selection of Duke-Owns parametrization set of nucleon structure function.

IHPR2(8):(D=10)

The maximum number of jet production per nucleon-nucleon interaction. When IHPR2(8)=0, jet production will be turned off. When IHPR2(8)<0, the number of jets production will be fixed for each NN collision at a value of abs(IHPR2(8)).

IHPR2(9):(D=0)

The switch to guarrantee at leat one minijet production per event(pp,pA or AA).

IHPR2(10):(D=0)

Option to print error warning messages that might happen. When a fatal error happens the current event will be abandoned and a new one is generated.

IHPR2(11):(D=1)

Choice of baryon production model.

=0 no baryon-antibaryon pair production, initial diquark treated as a unit.

=1 diquark-antidiquark pair production allowed, initial diquark treated as a unit.

=2 diquark-antidiquark pair production allowed, with the possibility for diquark to be split according to the "popcorn" scheme.(see the menu of jetset72)

IHPR2(12):(D=1)

Option to turn off the decay of partiles such as pi0,K0S,D+-,Lampda,Sigma+-,X-0,Omega-.

IHPR2(13):(D=1)Option to turn on single diffractive reactions.

IHPR2(14):(D=1)Option to turn on elastic scattering

IHPR2(15 - 17):not used

IHPR2(18):(D=0)

option to switch on B-quark production. Charm production is the default. When B-quark production is on, charm quark production is automatically off.

IHPR2(19):(D=1)Option to turn on initial state interaction

IHPR2(20):(D=1)

Option to turn off(IHPR2(20)=0) the fragmentation.

IHPR2(21):(D=0)

Option to retain the information of all particles including those which have decayed and the decay chain. The line number of the parent particle is KATT(I,3). The status of a partcile, whether it is a finally produced particle (KATT(I,4)=1) or a decayed particle (KATT(I,4)=11).

IHPR2(22)-IHPR2(50): not used.

HINT1(1):(GeV)

The center-of-mass energy per nucleon-nucleon collision.

HINT1(2):

The Lorenze transform variable beta from LAB to CM frame of nucelon nucleon collisions.

HINT1(3):The rapidity of the CM frame beta=tang(ycm).

HINT1(4):The rapidity of projectile y_proj.

HINT1(5):The rapidity of target y_targ.

HINT1(6):(GeV)The energy of projectile in the chosen frame.

HINT1(7):(GeV)The energy of target in the chosen frame.

HINT1(8):(GeV)The rest mass of projectile particles

HINT1(9):(GeV)The rest mass of target particles.

HINT1(10):(mb)

The averaged cross section for jet production per nucleon-nucleon collisions of the nuclear interaction(When very small compared to the total nucleon-nucleon cross section this is very close to the jet inclusive cross section HINT1(11)).

HINT1(11):(mb)

The averaged inclusive cross section for jet production per nucleon-nucleon collisions of the nuclear interaction.

HINT1(12):(mb)

The averaged inelastic cross section of nucleon-nucleon collisions.

HINT1(13):(mb)

The averaged total cross section of nucleon nucleon collisions.

HINT1(14):(mb)

The jet production cross section without shadowing effect.

HINT1(15):(mb)

The cross section to account for the projectile shadowing correction term in the jet cross section.

HINT1(16):(mb)

The cross section to account for the target shadowing correction term in the jet cross section.

HINT1(17):(mb)

The cross section to account for the cross term of shadowing correction in the jet cross section.

HINT1(18):(mb)

The cross section for jet production for the latest nucleon-nucleon collisions which depends on the impact parameters(i.e. HINT1(18)= HINT1(14)-a1*HINT1(15)-a2*HINT1(16)+a1*a2*HINT1(17)).

HINT1(19):(fm) The imapct parameter of the latest event.

HINT1(20):(rad)The orientation of the latest collision.

HINT1(21)-HINT1(25):

the three momenta, energy and mass of the first scattered parton in the specified hard collision per event with specified PT (This is before the final state radiation but after the initial state radiation).

HINT1(26)-HINT1(29):

The total momentum and energy of the partons in the specified hard collision from the final state radiation of the first scattered parton which are a little different from HINT1(21)-HINT1(24) due to the rearrangement of the parton showers with energy and momentum conservation.

HINT1(30):not used.

HINT1(31)-HINT1(35):

the three momenta, energy and mass of the second scattered parton in the specified hard collision per event with specified PT (This is before the final state radiation but after the initial state radiation).

HINT1(36)-HINT1(39):

The total momentum and energy of the partons in the specified hard collision from the final state radiation of the second scattered parton which are a little different from HINT1(31)-HINT1(34) due to the rearrangement of the parton showers with energy and momentum conservation.

HINT1(40):not used.

HINT1(41)-HINT1(45)

the three momenta, energy and mass of the first scattered parton in the latest hard collision of the latest event.

HINT1(46):

PT of the first scattered parton in the latest hard collision of the latest event.

HINT1(47)-HINT1(50):

The total momentum and energy of the partons in the latest hard collision from the final state radiation of the second scattered parton which are a little different from HINT1(41)-HINT1(44) due to the rearrangement of the parton showers with energy and momentum conservation.

HINT1(51)-HINT1(55)

the three momenta, energy and mass of the second scattered parton in the latest hard collision of the latest event.

HINT1(56):

PT of the second scattered parton in the latest hard collision of the latest event.

HINT1(57):

Correction factor for cross section of parton_nucleon interactins due to processes below pt HINT1(58):(mb)

The averaged cross section of a parton scattering off a nucleon which is used to simulate initial state interaction.

HINT1(59):(mb)

The averaged total cross section of the triggered jet production with specified P_T by HIPR1(10)(and switch by IHPR2(3))(usually, it is very close to the inclusive cross section HINT1(60) when the later is very small).

HINT1(60):(mb)

The averaged inclusive cross section of the triggered jet production with specified P_T by HIPR1(10)(and switch by IHPR2(3)).

HINT1(61):(mb)

The trigger jet production cross section without shadowing effect.

HINT1(62):(mb)

The cross section to account for the projectile shadowing correction term in the trigger jet cross section.

HINT1(63):(mb)

The cross section to account for the target shadowing correction term in the trigger jet cross section.

HINT1(64):(mb)The cross section to account for the cross term of shadowing correction in the trigger jet cross section.

HINT1(65):(mb)

The inclusive cross section for latest trigger jet production which depends on the impact parameters (i.e. HINT1(65)=HINT1(61)-a1*HINT1(62)-a2*HINT1(63) +a1*a2*HINT1(64)).

HINT1(67)-HINT1(70):

The total momentum and energy of the partons in the latest hard collision from the final state radiation of the second scattered parton which are a little different from HINT1(51)-HINT1(54) due to the rearrangement of the parton showers with energy and momentum conservation.

HINT1(71):not used.

HINT1(72)-HINT1(75):

Three parameters for the wood-saxon projectile nuclear distribution and the normalization, rho(x)=FNORM*(1.+W*(X/R)**2)/(1+EXP((X-R)/D) R=HINT1(72), D=HINT1(73), W=HINT1(74), FNORM=HINT1(75).

HINT1(76)-HINT1(79):

Three parameters for the wood-saxon target nuclear distribution and the normalization, rho(x)=FNORM*(1.+W*(X/R)**2)/(1+EXP((X-R)/D) R=HINT1(76), D=HINT1(77), W=HINT1(78), FNORM=HINT1(79).

HINT1(80)-HINT1(100):

The probability of 0-20 jets production per pp interaction.

IHNT2(1):

The atomic number of the projectile nucleus (=1 for hadron).

IHNT2(2):

The charge number of the projectile nucleus, if the projectile is a hadron it gives the charge of that hadron.

IHNT2(3):

The atomic number of the target nucleus(=1 for hadron).

IHNT2(4):

The charge number of the terget nucleus,if the target is a hadron it gives the charge of that hadron.

IHNT2(5):The ID number of projectile hadrons(=0 for nucleus).

IHNT2(6):The ID number of target hadrons(=0 for nucleus).

IHNT2(7)-IHNT2(8):not used

IHNT2(9):

The parton id of the first scattered parton in the specified hard collision per event with fixed PT.

IHNT2(10):

The parton id of the second scattered parton in the specified hard collision per event with fixed PT.

IHNT2(11):

The sequence number of projectile nucleon of the latest nucleon-nucleon interaction in the latest event.

IHNT2(12):

The sequence number of target nucleon of the latest nucleon-nucleon interaction in the present event.

IHNT2(13):status of the latest soft LUND type exicitation:

=1 double diffractive;

=2 single diffractive

=3 non-single diffractive.

IHNT2(14):

The parton id of the first scattered parton in the latest hard collision of the latest event.

IHNT2(15):

The parton id of the second scattered parton in the latest hard collision of the latest event.

IHNT2(16):

parameter to indicate the initialization of the the cross sections(=1). When given value 1 the initilization of pythia will used un-shadowed structure functions to evaluate the maximum cross sections.

IHNT2(17)-IHNT2(50):not used.

Example Programs (Go back to the main manual)

CHARACTER FRAME*8,PROJ*8,TARG*8

COMMON/HIMAIN1/NATT,EATT,JATT,NT,NP,N0,N01,N10,N11

COMMON/HIMAIN2/KATT(130000,4),PATT(130000,4)

C ********information of produced particles

COMMON/HIJJET1/NPJ(300),KFPJ(300,500),PJPX(300,500),PJPY(300,500)

&,PJPZ(300,500),PJPE(300,500),PJPM(300,500),NTJ(300),KFTJ(300,500)

&,PJTX(300,500),PJTY(300,500),PJTZ(300,500),PJTE(300,500),PJTM(300,500)

COMMON/HIJJET2/NSG,NJSG(900),IASG(900,3),K1SG(900,100),K2SG(900,100)

&,PXSG(900,100),PYSG(900,100),PZSG(900,100),PESG(900,100),PMSG(900,100)

C ********information of produced partons

EFRM=200.0

FRAME='CMS'

PROJ='A'

TARG='A'

IAP=197

IZP=79

IAT=197

IZT=79

CALL HIJSET(EFRM,FRAME,PROJ,TARG,IAP,IZP,IAT,IZT)

C ********Initialize HIJING

BMIN=0.0

BMAX=0.0

DO 2000 I_event=1,100

CALL HIJING(FRAME,BMIN,BMAX) C

DO 1000 I=1,NATT

IF(LUCHGE(KATT(I,1)).NE.0) THEN

C ******** this select charged particles only

C ******** information of produced particles

C ******** is stored in common blocks HIMAIN1 and HIMAIN2

ENDIF

1000 CONTINUE

2000 CONTINUE

STOP

END

IHPR2(3)=1(2,for direct photon production)

HIPR1(10)=P_T(-P_T for jets above P_T)

History of Updates (Go back to the main manual)

(1) An option is added to keep the information of all particles including the decay chains. The switch of this option is IHPR(21)=1 (default=0). The array KATT(130000,2) in COMMON/HIMAIN2/ is expanded to KATT(130000,4). K(I,3) is the line number of the parent particle of the current line which is produced via a decay. KATT(I,4) is the status number of the particle: 11=particle which has decayed; 1=finally or directly produced particle.

(2)Heavy flavor production processes through q+\bar{q}-->c+\bar{c} and g+g-->c+\bar{c} have been switched on. Charm production is the default, B-quark option is IHPR2(18)=1 (default=0). Note that when B-quark production is switched on, charm quark is automatically off.

(3) A subroutine PROFILE(XB) is added to assist the simulation of minimum biased events of proton-nucleus and nucleus-nucleus collisions. Refer to the examples in hijing.tex for the simulation.