====== ======= ====== ====== / | | | | | / | | | | | / | | | |==== / | | | | ====== | ====== | Copyright 2001, 2004 by Zack Sullivan ZTOP NLO differential s-channel and t-channel single-top-quark production ---------------------------------------------------------------------------- ZTOP is a FORTRAN program that calculates the fully differential spin- averaged production of a top quark plus one jet at next-to-leading order (i.e. through t + 2 jets). The program is a coding of the phase space slicing with two cutoffs calculation presented in the papers below. Please refer to these papers: 1. B.W. Harris, E. Laenen, L. Phaf, Z. Sullivan, and S. Weinzierl, Phys. Rev. D 66, 054024 (2002) [arXiv:hep-ph/0207055]. 2. Zack Sullivan, Phys. Rev. D 70, 114012 (2004) [arXiv:hep-ph/0408049]. ---------------------------------------------------------------------------- Contents: 0. License 1. Compiling 2. s-channel input file details 3. t-channel input file details 4. Various notes ---------------------------------------------------------------------------- 0. License: All code provided here is written and copyrighted by Zack Sullivan (C) 2004, except where noted in the source codes. These source codes may be used and redistributed without permission of the author as long as the original code is included in an unaltered form. This code is intended for academic use. While extensive testing has been done to confirm that there are no bugs under current FORTRAN standards, the author makes no guarantee of fitness for any use or correctness. ---------------------------------------------------------------------------- 2. Compiling What you will need/want to edit: makefile - choose compiler options cteqfastpdf.f - set explicit path to CTEQ PDF tables (I've included 5L, 5M1) NOTE: This file is a VERY fast interface to the CTEQ PDF tables, which speeds up PDF evaluation by a factor of 10. cf. Zack Sullivan, ``Fast evaluation of CTEQ parton distributions in Monte Carlos,'' arXiv:hep-ph/0407033. The included makefile includes good choices of compiler flags for the g77 and Intel compilers. To get the executables ZTOPschan.x and ZTOPtchan.x, just type: make You should probably run some tests by changing to the examples/ subdirectory, and executing the file test.bat. This may take a few minutes, but you should verify that the distributions placed in the subdirectories test/schan/ and test/tchan/ agree within round-off errors to the ones in schan/ and tchan/. These numbers were generated using g77, but the Intel compiler produces much faster code. These files are produced with about 1/10 the number of points used for publication. For your own evaluations, use the higher statistics - the programs are fast enough to handle it. ---------------------------------------------------------------------------- 2. s-channel production Executable: ZTOPschan.x Sample input files: ls_nc.in, ls_dc.in, ls_jc.in, ls_tc.in s_nc.in, s_dc.in, s_jc.in, s_tc.in WARNING: There is some error checking, but using parameters other than the recommended ones (indicated with a *) can lead to peculiar behavior. Structure of input: (sample input files are documented) Line 1: Pick order of calculation * 1 : LO 2 : NLO correction only * 3 : Full NLO Line 2: Base factorization and renormalization scale. Note there is not an option in this release to treat the scales differently. 0 : PT of top quark 1 : top quark transverse mass 2 : PT of highest-PT jet * 3 : top quark-b jet invariant mass (just like Drell-Yan) * 4 : top-quark mass (not a great choice for LO) 5 : s^hat 6 : W boson mass Line 3: modifies line 2. * 0 : Do not modify the scales above 1 : 2*(line 2) 2 : (line 2)/2 Lines 4, 6, 8: Set the initial number of iterations for vegas for LO, NLO 2 body, and NLO 3 body (use something like 5, 5, 6). For graphing, this number is doubled. Lines 5, 7, 9: Set the initial number of points for vegas for LO, NLO 2 body, and NLO 3 body. A good ratio to use is 1 : 1.2: 10, e.g. 100000, 120000, 1000000. The error will be dominated by the number of points in line 9. For graphing, this number is multiplied by 10. Line 10: top-quark mass in GeV 175d0 is typical as of June 2004 Line 11: W boson mass in GeV 80.4d0 is typical as of June 2004 Line 12: sqrt(S) in TeV 1.96d0 is the energy of the Tevatron Run II, 1.8d0 was Run I, 14d0 is LHC Line 13: collider type * 1,2: p-pbar for Tevatron * 3 : p-p for LHC Line 14: CTEQ PDF set. Currently the main function is written to used CTEQ PDFs through the PFTOPDG interface. See accompanying PDF interface file for all numbers. * 53 : CTEQ 5L (use for LO cross sections) * 58 : CTEQ 5M1 (use for NLO cross sections) 64 : CTEQ 6L1 (use for LO cross sections) 61 : CTEQ 6M (use for NLO cross sections) # : Other choices 41-49 are CTEQ 4, 1-9 51-59 are CTEQ 5, 1-9 61-64 are CTEQ 6, 1-4 6100-6140 are CTEQ 6M, 100-140 6200-6240 are CTEQ 61, 00- 40 Line 15: Calculate t production? For comparison it is more useful to check just t or t_bar, but not both. * 1 : Yes 0 : No Line 16: Calculate t_bar production? For comparison it is more useful to check just t or t_bar, but not both. * 1 : Yes 0 : No Line 17: k_T cone size. Fixed cones are roughly k_T cones/1.35, e.g. 1d0 is like a fixed cone of 0.74. WARNING: If you use a cone size that is different and try to compare, your answer can be off by more than all theoretical uncertainties combined. * 1d0 : Other reasonable choices 0.54d0, 1.35d0 (like fixed cones 0.4, 1.0) Line 18: k_T cone r_sep. Currently ignored in the code. * Set it equal to line 17 for now. Line 19: Cuts. Also defines the suffix for output files. * 0 : No cuts (nc) * 1 : Require 2 jets (not including top) passing cuts on lines 26, 27. (dc) * 2 : Require at least 1 jet (not including top) passing first cut on lines 26, 27, and any cuts on top quark. (jc) * 3 : Require exactly 1 jet (not including top) passing first cut on lines 26, 27, and any cuts on top quark. Other jets must fail third cuts on lines 26, 27. (tc) Line 20: Smearing * 0 : none 1 : Call simple Gaussian smearing routine on jets 80%/sqrt(E)+5% 2 : 1 + smear top quark (bad choice) Line 21: Vary soft and collinear cut parameters. Used to test for numerical independence of cuts. 0 : Vary delta_soft 1 : Vary delta_collinear * 2 : Vary delta_collinear = delta_soft/(line 24) Lines 22-23: Loop over minimum (line 22) to maximum (line 23) exponents. * 6 : Do not change this unless you understand the code Line 24: Set collinear/soft factor * 300d0 : Do not change this unless you understand the code Line 25: Prefix string (prepended to all output files) * Put whatever you want. Line 26: PT_min cuts (GeV) for jet_1, top quark, jet_2. Cut on jet_2 must be <= cut on jet_1 (since jets are PT_ordered). Top quark cut is only applied if eta cut on line 27 is greater than 10^-5. * Typical values might be 15d0 0d0 15d0 Line 27: Eta_max cuts for jet_1, top quark, jet_2. Cut on jet_2 should be >= cut on jet_1. Top quark cut is only applied if the second value is greater than 10^-5. * Typical values might be 2.5d0 0d0 2.5d0 ---------------------------------------------------------------------------- 3. t-channel production Executable: ZTOPtchan.x Sample input files: lt_nc.in, lt_dc.in, lt_jc.in, lt_tc.in t_nc.in, t_dc.in, t_jc.in, t_tc.in WARNING: There is some error checking, but using parameters other than the recommended ones (indicated with a *) can lead to peculiar behavior. Structure of input: (sample input files are documented) Line 1: Pick order of calculation * 1 : LO 2 : NLO correction only * 3 : Full NLO Line 2: Base factorization scale for light-quark line Line 4: Base factorization scale for heavy-quark line Line 6: Base renormalization scale for light-quark line Line 8: Base renormalization scale for heavy-quark line 0 : PT of top quark 1 : top quark transverse mass 2 : PT of highest-PT jet 3 : top quark-highest-PT jet invariant mass * 4 : top-quark mass (not a great choice for LO) 5 : s^hat * 6 : Q^2 (best choice for light-quark line, massless DIS scale) * 7 : Q^2+mt^2 (best choice for heavy-quark line, massive DIS scale) The rest are nonsensical unless looking for t+2 jets 8 : M_jj dijet invariant mass 9 : Q^2+M_jj^2 10 : MT_jj dijet transverse mass 11 : Q^2+MT_jj^2 (fac) 12 : scalar sum of all PT 13 : scalar sum of all transverse masses Lines 3, 5, 7, 9 modify lines 2, 4, 6, 8, respectively. * 0 : Do not modify the scales above # : Any other number is assumed to be the fraction of the scale/100, e.g. 200 (50) on line 3 would multiply the scale in line 2 by 2 (0.5). Lines 10, 12, 14: Set the initial number of iterations for vegas for LO, NLO 2 body, and NLO 3 body (use something like 5, 5, 6). For graphing, this number is doubled. Lines 11, 13, 15: Set the initial number of points for vegas for LO, NLO 2 body, and NLO 3 body. A good ratio to use is 1 : 1: 10, e.g. 100000, 100000, 1000000. The error will be dominated by the number of points in line 15. For graphing, this number is multiplied by 10. Line 16: top-quark mass in GeV 175d0 is typical as of June 2004 Line 17: W boson mass in GeV 80.4d0 is typical as of June 2004 Line 18: sqrt(S) in TeV 1.96d0 is the energy of the Tevatron Run II, 1.8d0 was Run I, 14d0 is LHC Line 19: collider type * 1,2: p-pbar for Tevatron * 3 : p-p for LHC Line 20: CTEQ PDF set. Currently the main function is written to used CTEQ PDFs through the PFTOPDG interface. See accompanying PDF interface file for all numbers. * 53 : CTEQ 5L (use for LO cross sections) * 58 : CTEQ 5M1 (use for NLO cross sections) 64 : CTEQ 6L1 (use for LO cross sections) 61 : CTEQ 6M (use for NLO cross sections) # : Other choices 41-49 are CTEQ 4, 1-9 51-59 are CTEQ 5, 1-9 61-64 are CTEQ 6, 1-4 6100-6140 are CTEQ 6M, 100-140 6200-6240 are CTEQ 61, 00- 40 Line 21: Calculate t production? For comparison it is more useful to check just t or t_bar, but not both. * 1 : Yes 0 : No Line 22: Calculate t_bar production? For comparison it is more useful to check just t or t_bar, but not both. * 1 : Yes 0 : No Line 23: k_T cone size. Fixed cones are roughly k_T cones/1.35, e.g. 1d0 is like a fixed cone of 0.74. WARNING: If you use a cone size that is different and try to compare, your answer can be off by more than all theoretical uncertainties combined. * 1d0 : Other reasonable choices 0.54d0, 1.35d0 (like fixed cones 0.4, 1.0) Line 24: k_T cone r_sep. Currently ignored in the code. * Set it equal to line 23 for now. Line 25: Cuts. Also defines the suffix for output files. * 0 : No cuts (nc) * 1 : Require 2 jets (not including top) passing cuts on lines 32, 33. (dc) * 2 : Require at least 1 jet (not including top) passing first cut on lines 32, 33, and any cuts on top quark. (jc) * 3 : Require exactly 1 jet (not including top) passing first cut on lines 32, 33, and any cuts on top quark. Other jets must fail third cuts on lines 32, 33. (tc) Line 26: Smearing * 0 : none 1 : Call simple Gaussian smearing routine on jets 80%/sqrt(E)+5% 2 : 1 + smear top quark (bad choice) Line 27: Vary soft and collinear cut parameters. Used to test for numerical independence of cuts. 0 : Vary delta_soft 1 : Vary delta_collinear * 2 : Vary delta_collinear = delta_soft/(line 30) Lines 28-29: Loop over minimum (line 28) to maximum (line 29) exponents. * 6 : Do not change this unless you understand the code Line 30: Set collinear/soft factor * 300d0 : Do not change this unless you understand the code Line 31: Prefix string (prepended to all output files) * Put whatever you want. Line 32: PT_min cuts (GeV) for jet_1, top quark, jet_2. Cut on jet_2 must be <= cut on jet_1 (since jets are PT_ordered). Top quark cut is only applied if eta cut on line 33 is greater than 10^-5. * Typical values might be 15d0 0d0 15d0 Line 33: Eta_max cuts for jet_1, top quark, jet_2. Cut on jet_2 should be >= cut on jet_1. Top quark cut is only applied if the second value is greater than 10^-5. * Typical values might be 2.5d0 0d0 2.5d0 ---------------------------------------------------------------------------- 4. Common structural notes (things you might want to look at): If you wish to use alternate cut schemes, the logic for cuts is in scuts.f and tcuts.f. If you wish to plot alternate quantities, e.g. delta_phi_jj, delta_eta_jj, etc., the histogramming is performed in shist.f and thist.f. There are two things to be careful about: 1. The graphing routine may be entered with 2 or 3 jets defined, so some checking must be done. 2. s-channel ps(0,3) is a b jet. t-channel ps(0,3) or ps(0,5) could be a b jet. The fractional probability is passed in. See thist.f to understand how to deal with this. The CKM matrix is defined in the smain.f and tmain.f files. Currently V_td = V_ts = 0, V_tb = 1, with other values commented out. The programs are fairly modular. To change how PDFs are set up, edit smain.f or tmain.f, and use any set that provides a PFTOPDG interface. Phase space generation is separated from the momentum-dependent part of the matrix element code (up to overall factors). So even VEGAS could be swapped out fairly transparently. ----------------------------------------------------------------------------