**************************** * * * Update notes * * * * HYDJET version 1.9 * * * **************************** (Last updated 26 October 2020) HYDJET version 1.9 is a direct continuation of previous versions. It should be used with PYQUEN1.5.4 (or later), the latest PYTHIA6 (PYTHIA6.401 or later versions), and also jetset_73.f with extended LUJETS size in the case if using the standard JETSET subroutines and functions to manipulate with the event record and to provide various event data are needed. ----------------------------------------------------------------------------- HYDJET1.9.2: 26 October 2020 1. Common block HYJEMB with parameter 'ifPyqEmb' has been introduced to the subroutine HYEVNT. It is used to correct number of NN sub-collisions for HYDJET embedding mode. HYDJET1.9.1: 28 November 2019 1. The parameter 'bfix' has been introduced to the subroutine HYEVNT. 2. The subroutine HYJVER to print out HYDJET versioning is introduced. 3. Several technical adjustments for Fortran 2018 standard have been done. HYDJET1.9: 1 July 2013 1. The triangular flow for soft component is introduced via a special modulation of the freeze-out hypersurface. Third Fourier harmonic of azimuthal particle distribution appears relatively to new angle 'psi3' (randomly distributed with respect to the direction of the impact parameter, and stored in new common block HYPSI3). HYDJET1.8: 17 July 2011 1. The set of basic resonances (rho, omega, eta, eta', phi, K*, Lambda) for the soft component is implemented. The ratios between primary hadrons are taken from the thermal model. Previously, only final pions, kaons, protons and neutrons were considered for the soft component. HYDJET1.7: 6 April 2011 1. The additional von Neumann rejection/acceptance procedure generating hadron spectra of soft component in accordance with the Cooper-Frye freeze-out prescription is introduced. 2. The hydro-inspired parametrization for the momentum and spatial anisotropy of soft hadron emission source is implemented. HYDJET1.6: 18 March 2009 1. The possibility to switch on or off the decay of a given particle species (for soft as well as for hard components) is included. It may be specified now in main user's routine by standard settings of the PYTHIA variables MDCY(KC,1), where the KC=PYCOMP(KF) is the compressed particle code and KF is the full particle code. HYDJET1.5: 19 December 2007 1. HYDJET1.5 uses PYQUEN1.5 instead of PYQUEN1.4 (see pyquen1_5.update). HYDJET1.4 : 27 October 2007 1. HYDJET1.4 uses PYQUEN1.4 instead of PYQUEN1.3 (see pyquen1_4.update). 2. All calculations in HYDJET1_4 have been completely transformed from using the REAL variables to using the DOUBLE PRECISION variables. Thus all real HYDJET parameters and functions to be used, should be described as 'double precision' in main user's routine. However one exception is still hold: JETSET routine elements. Copying the original DOUBLE PRECISION output particle information from HYDJET arrays (common block HYJETS) to JETSET arrays (common block LUJETS) allows the user to perform easily some useful manipulations with the event record using standard JETSET subroutines and functions (to exclude unstable or undetectable particles, to list an event, to provide various event data, etc.). Since jetset_73.f operates on REAL variables, its arrays 'p' and 'v', as well as other REAL parameters and functions of JETSET to be used, should be described still as 'real' in main user's routine. Modified common block HYJETS contains now the original event record in the same format as /LUJETS/, but in DOUBLE PRECISION for particle-momentum and particle-vertex arrays: COMMON /hyjets/ nhj,nhp,khj(150000,5),phj(150000,5),vhj(150000,5) nhj - total event multiplicity nhp - dummy to ensure as even number of integers khj(i,1-5) - particle codes phj(i,1-5) - particle four-momentum and mass vhj(i,1-5) - particle vertex, production time and lifetime Some re-ordering of parameters in HYDJET common blocks HYIPAR, HYJPAR and HYPYIN has been performed. 3. Wood-Saxon nucleon distribution is implemented in HYDJET nuclear geometry instead of hard sphere approximation (new function RHOAA). Tabulation of impact parameter dependences of nuclear thickness function and nuclear overlap function is performed in HYINIT subroutine (arrays BAB, TAB and TAAB). The number of nucleons-participants and binary nucleon-nucleon subcollisions, and also differential inelastic AA cross section (if ifb=1) are calculated using these tabulated functions. Maximum allowed value of impact parameter is three times of the nuclear radius. 4. Output parameters NBCOL and NPART are DOUBLE PRECISION variables now, and so they should be described as 'real' in main user's routine. 5. Default values of HYDJET parameters for hydro flow have been changed: YTFL(D=1.5), YLFL(D=4.), TF(D=0.1). HYDJET1.3: 3 October 2007 1. HYDJET1.3 uses PYQUEN1.3 instead of PYQUEN1.2 (see pyquen1_3.update). 2. Now all HYDJET input parameters should be specified by calling subroutine of HYDJET initialization, HYINIT: CALL hyinit(energy,A,ifb,bmin,bmax,bfix,nh). HYINIT should be called one time (before cycle on events). One HYDJET event is generated by calling HYEVNT routine (renamed HYDRO): CALL hyevnt. 3. New internal common block HYPYIN (containing some input HYDJET parameters) has been created. 4. Isospin effect is introduced in HYDJET. HYINIT subroutine calculates hard scattering cross section and HYHARD subroutine generates pp, pn or nn hard sub-collisions, in accordance with the probability dependent on Z/A ratio for given nucleus. 5. Impact parameter dependent parameterization of nuclear shadowing effect for gluons and light sea quarks (u,d,s) (provided by Konrad Tywoniuk, Oslo University: subroutines GGSHAD, GGINTER, SPLINE and function SEVAL) is introduced in the model for hard part of event (new subroutine SHAD1). The shadowing parameterization is implemented for Pb, Au, Pd or Ca ions. New parameter in common block HYJPAR controls switching shadowing: ishad=0 - shadowing is switched off, ishad=1 - shadowing is switched on. New internal parameter 'noquen' in PYQUEN common block PARIMP allows one to generate the spatial jet production vertex in PYTHIA (which is necessary for calculation of shadowing correction) without subsequent medium-induced rescattering in the case nhsel=1 or nhsel=3. 6. Bug fix in subroutine HSIN: differential inelastic AA cross section is determined more accurately now. The bug had very slight influence on impact parameter distribution for minimum-bias event generation and light ions. 7. Bug fix in function HFTAA in calculation of nuclear overlap function for non-lead ions. It resulted in some underestimation in number of nucleon-nucleon sub-collisions and jets for light ions. 8. Bug fix in function HFUNC2 in calculation of mean number of nucleon participants in non-central collisions. The bug had very slight influence on the impact parameter dependence of number of nucleon participants. 9. In the case of selecting nhsel=3 or nhsel=4, multiplicity of soft part is forced to be zero independently on 'nh' value. HYDJET1.2: 18 June 2007 1. HYDJET1.2 uses PYQUEN1.2 instead of PYQUEN1.1 (see pyquen1_2.update). It can be used for different beam energies (input parameter 'energy' specifies the c.m.s. energy per nucleon pair). 2. Initial parameters of quark-gluon plasma and some energy loss settings can be varied now by user using PYQUEN1_2 common block PYQPAR: COMMON /pyqpar/ T0,tau0,nf,ienglu,ianglu T0 - initial QGP temperature for central Pb-Pb collisions (allowed range is 0.2 GeV < T0 < 2 GeV, default value is T0=1 GeV); tau0 - proper time of QGP formation (allowed range is 0.01 < tau0 < 10 fm/c, default value is tau0=0.1 fm/c); nf - number of active quark flavours in QGP (nf=0, 1, 2 or 3, default value is nf=0); ienglu - flag to fix type of medium-induced partonic energy loss (ienglu=0 - radiative and collisional loss, ienglu=1 - radiative loss only, ienglu=2 - collisional loss only, default value is ienglu=0); ianglu - flag to fix type of angular distribution of emitted gluons (ianglu=0 - small-angular, ianglu=1 - wide-angular, ianglu=2 - collinear, default value is ianglu-0). 3. New subroutine HYINIT has been created for HYDJET initialization: - PYTHIA initialization at given c.m.s. energy per nucleon pair; - calculation of total inelastic NN cross section at given energy; - calculation of hard scattering NN cross section at given ptmin and energy; - calculation of number of participants & binary collisions at Pb+Pb (b=0). 4. There are two new parameters in COMMON BLOCK HYJPAR: sigin - total inelastic NN cross section at given c.m.s. energy (it is calculated by Pythia, but also can be changed by user in main routine before call HYINIT, allowed range is 10 mb < sigin < 200 mb); sigjet - hard scattering NN cross section at given ptmin and energy (it is calculated by Pythia and can not be changed by user). 5. Freeze-out temperature Tf is included in COMMON BLOCK HYFLOW, and now can be varied by user (allowed range is 0.08 GeV < Tf < 0.2 GeV, default value is Tf=0.14 MeV) HYDJET1.1 : 26 April 2006 1. Main difference from previous version is that HYDJET1.1 uses PYQUEN1.1 instead of PYQUEN1.0 (see pyquen1_1.update) and PYTHIA6.401 (or later PYTHIA versions). 2. Parameter mstp(111)=0 is used in HYHARD routine to switch off hadronization before calling pyquen instead of mstj(1)=0 -----------------------------------------------------------------------