D0 Common Alpgen Studies

Proposed settings in mcp17 for V(=W/Z)+jets processes

They basically follow the CSMC settings for mcp14 (some cuts are looser)

New in Alpgen v2.05: MLM matching cuts

Factorization scale: iqopt=1=mV^2+Sum(mT^2)
pT(j) > 8 GeV; pT(Q) > 0; pT(l) > 0; ETmiss > 0
|eta(j)| < 5; |eta(Q)| < 5; |eta(l)| < 10
DR(j,j) > 0.4; DR(Q,Q) > 0; DR(j,l) > 0
Single charm production is treated as "j" case
MLM jet cuts: ETclus=pT(j), Rclus=DR(j,j)
MLM matching cuts: pT > 8 GeV, DR < 0.7
Inclusive jet multiplicity bin -- analysis dependent.
Need inputs from the physics groups.
The top group's preference:

Factorization scale for the ttbar events: as above

Heavy quark masses: m_t = 175, m_b = 4.75, m_c = 1.55 GeV

mcp14 studies/settings

Steering Committee:

Members	Group	Activities
S. Muanza (chair)	Simulation/NP	Coordination, MCFM, Prod., Matching, Alpgen+Pythia cardfiles
C. Biscarat (co-chair)	Simulation/Higgs	Prod. Script, Prod. Book-keeping, Prod., Higgs group Rep., Alpgen cardfiles
S. Eno (ex-officio)	Simulation/EW	Simulation expert
A. Kharchilava (ex-officio)	Higgs	MC expert
S. Snyder	Higgs	Higgs group Rep.
M. Zielinski	Top	Top group Rep., Prod.
C. Schwanenberger	Top	Top group Rep., Alpgen cardfiles, Prod., Pre-prod. tests
T. Adams	NP	NP group Rep.
E. Perez	NP/Top	NP group Rep., MC expert, Analysis
M. Begel	Simulation/QCD	MC expert, QCD group Rep., Alpgen Phase Space Sampling, Matching
A. Kupco	JES/QCD	QCD group Rep., Analysis

Analysers:

Common Proposal:

Authors: C. Biscarat, S. Muanza
Talk given at the NP meeting (26-Feb-2004): "First attempt towards a general prescription for the use of ALPGEN+PYTHIA at DØ"
Talk given at the Conveners meeting (12-Mar-2004): "First attempt towards a general prescription for the use of ALPGEN+PYTHIA at DØ"
Alpgen version: v1.3.3
Alpgen PDF: CTEQ5L
Alpgen-Pythia PDF: CTEQ5L + "Tune A" UE
Remove the charm component from V+jets

Tauola: tau.cmd files to be checked (discrepancies top group and D0 standard BR, to be checked)
EvtGen: short list (5 particles - to be checked with Alberto Sanchez, OLD); possible implementation of the new B-hadrons and C-hadrons lists (underway...)

Vary 0.5 < Qfact < 2 around the factorization scale for both the fixed and dynamic case
Change the PDFs
Vary the pT(q) and pT(Q) cuts

Status and Plans:

Documentation:

Grid Size Study(6p,W+4p, W+2b) (text) by M. Begel and plots ps, pdf
Alpgen stability study - Grids, preselection and unweighting by M. Begel and M. Zielinski

Known Bugs and Caveats:

When comparing the results of the previous data % MC comparisons, please beware that the Alpgen events were not produced in a fully tracable way and that the seetings were quite different. Also the matching procedure applied were not common either
Any results from this work will be valid only for the Alpgen+Pythia interface, not for Alpgen+Herwig, especially since the angular ordering (present in Herwig and not in Pythia) makes the PS implementations quite different in these 2 generators
Any results from this work will be valid only for the MLM matching prescription (it is beyong the scope of this "Task Force" to apply the CKKW matching)

Links: