The HV1.0 Monte Carlo Steve Mrenna, Peter Skands, and MJS

Features and Important Facts The new program can do more things –Final state can be in form of Les Houches accord event record –All v-hadrons in final state; user must decay them –Stable v-hadron and unstable-v-hadron standard-model decay products NEW HEPEVT hadron-level output –Two approaches to v-sector Scaled-up QCD User-defined theory with independent fragmentation NEW –More production processes Z’ Others in development (not tested yet)

Features and Important Facts User Input has changed and is still changing  –User defines the process via standard Pythia call NEW –User defines the theory through two upload files and standard Pythia calls NEW Currently CALL PYUPDA (Pythia < 6.410) Moving to CALL PYSLHA (Pythia = 6.410) –HV.input.par file in process of adjustment Some “IMODE”s of operation no longer active, new ones added –New input file needed to control fragmentation, other settings; not present yet

HV.input.par '! IMODE 1 lha + hepevt output (UE subtlety, see README) 2 lha output (vhadron level) 3 lha input -> pythia output (not tested) 4 lha output (parton level) 5 hepevt output (hadron level)' 3/15/07 !!!! only use modes 2,4,5 for now '! In modes 2,4 program shuts off fragmentation of proton remnants in initial state, showering/hadronization in final state '! Add 60 to IMODE for A0,H0 bosons to be standins for vpions in lha file' '! IHVTHY is scaled-up vQCD, 9 is user-defined theory '! number of flavors inferred from input file where vquarks x00000f appear '! scale for scaled-up vQCD inferred from vQCDscale (code x000100) '! '! IFRAG: 0 default, 1 independent vfragmentation, '! 2 scaled-up qcd hadronization, 3 scaled-up qcd showering and fragmentation' '! Default is ifrag=3 for ihvthy0=1, ifrag=1 for ihvthy=9 '! '! The START LINE initiates read-in' '! The next line reads in:' '! IMODE,IDIAGN,NEV,IRANDM,ICLDR,IHVTHY0,IFRAG' 'START' 2,9,3, ,0,9,0 ! do not insert a comment line next myinput ! this line must be the input file prefix followed by a space ! myoutput ! this line must be the output file prefix followed by a space ! MSEL=0 ! user control ! MSUB(141)=1 ! Z' production ! MSTP(44)=3 ! no interference ! MSTP(47)=0 ! phase space Z' CKIN(1)=1650.D0 ! minimum partonic collision energy 'END' Note masses and decays are no longer set here… But the process (Z’ production) is set here Note the running modes have changed! Use 2,4,5 only Temporary – is this needed anymore?

gv E dv dvbar E uv uvbar E vcluster E vstring E vindep E CMvshwr E Lambda_V E piv E rhov E a_2v E piv+ piv E rhov+ rhov E a_2v+ a_2v E etav E Input v-sector (PYUPDA version) pdg code name conjugate mass width decay info Decays

Input Z’ Br’s (PYUPDA version) 32 Z' E Note all decays are disabled except those to v-quarks

Output MODE 2: V-hadrons is pizero, is piplus; no “neutrinos” anymore

Output MODE 4: Can you use this? How much information about the new v-particles do you need?

Output Mode 5: Hadrons Same as before, except now the new 6000xxx particles appear in the HEPEVT record This will cause problems for the event display program However we can either –Keep a mode in the current HV program so that 6000xxx particles are replaced with H0, A0 (this is currently the case, add 60 to IMODE –Write a script to convert all 6000xxx particles to something the programs recognize –Convert the programs to recognize 6000xxx particles

Summary Many advances but not stable yet Currently must use a non-standard Pythia version because of problems and bugs Usable I think! But will need to adjust input details as time goes on Need to decide on output modes; is current arrangement for output mode 4 ideal, or must it be altered? How should we move away from using H0/A0 in our code? –How are Pythia/GEANT/Athena to be taught about the new particles and their properties, which are needed even in mode 4? New theories can also be studied now, but that’s for the future PYUPDA will move to PYSLHA when Atlas moves to Pythia 6.411