Configuration#

Configuration files support JSON-like syntax and contain general steering parameters for a run, FOAM parameters, kinematic cuts and parameters of the Standard Model. The configuration can be split into several files and included to index.conf file by .include <relative or absolute path to file> macro.

Cross section structure#

The cross section of the electron-positron process at the one-loop level can be divided into four parts:

\(\hat{\sigma}^{\text{1-loop}} = \hat{\sigma}^{\mathrm{Born}} + \hat{\sigma}^{\mathrm{virt}}(\lambda) + \hat{\sigma}^{\mathrm{soft}}(\lambda, \omega) + \hat{\sigma}^{\mathrm{hard}}(\omega),\)

and the cross section of the partonic process at the one-loop level can be divided into five parts:

\(\hat{\sigma}^{\text{1-loop}} = \hat{\sigma}^{\mathrm{Born}} + \hat{\sigma}^{\mathrm{virt}}(\lambda) + \hat{\sigma}^{\mathrm{soft}}(\lambda, \omega) + \hat{\sigma}^{\mathrm{hard}}(\omega) + \hat{\sigma}^{\mathrm{brdq}}(\omega),\)

where \(\hat{\sigma}^{\mathrm{Born}}\) is the Born level cross section, \(\hat{\sigma}^{\mathrm{virt}}\) is the contribution of virtual (loop) corrections, \(\hat{\sigma}^{\mathrm{soft}}\) corresponds to the soft photon emission, \(\hat{\sigma}^{\mathrm{hard}}\) is the hard photon emission part (with energy \(E_{\gamma} > \omega\)), and \(\hat{\sigma}^{\mathrm{brdq}}\) corresponds to quark mass subtraction. Auxiliary parameters \(\lambda\) (fictitious “photon mass” which regularizes infrared divergences) and \(\omega\) (photon energy which separates the regions of the phase space associated with the soft and hard emissions) cancel out after summation. Also there is an option in ReneSANCe to include in calculation the case with two photons in initial state for NC DY \(\hat{\sigma}^{\mathrm{Ibaa}}\) (photon fusion) and the case with one photon and one quark or one gluon and one quark in initial state for NC and CC DY \(\hat{\sigma}^{\mathrm{Ibaq}}\) (inverse bremsstrahlung contribution). In the last case there are two parts of quark mass subtraction \(\hat{\sigma}^{\mathrm{Ibs1}}\) (NC and CC DY) and \(\hat{\sigma}^{\mathrm{Ibs2}}\) (NC DY only).

The calculation of the total cross-section in ReneSANCe generator is divided into separate branches according to kinematics and all the branches have their own settings. All branches are named as corresponding part of cross section, while Virt branch means Born+Soft+Virt contributions.

General parameters#

outputDir [string]#

set output directory in which results are stored

Process parameters#

pid [integer]#

defines a process to calculate. Processes with pid>200 can be used only with ReneSANCe_pp binary.

  • 101: \(e^+e^- \to e^-e^+\),

  • 102: \(e^+e^- \to ZH\)

  • 103: \(e^+e^- \to \mu^-\mu^+\),

  • 104: \(e^+e^- \to \tau^-\tau^+\),

  • 201: \(hh \to e^-e^+X\),

  • 202: \(hh \to \mu^-\mu^+X\)

  • 203: \(hh \to \tau^-\tau^+X\),

  • 211: \(hh \to e^-\bar\nu_e X\),

  • 212: \(hh \to \mu^-\bar\nu_\mu X\),

  • 213: \(hh \to \tau^-\bar\nu_\tau X\),

  • 221: \(hh \to \nu_e e^+ X\),

  • 222: \(hh \to \nu_\mu \mu^+ X\),

  • 223: \(hh \to \nu_\tau \tau^+ X\).

ecm [double]#

sets collider energy in the center-of-momentum frame.

alr [integer]#

switches generation mode:

  • 0: \(\sigma\),

  • 1: \(\sigma_{RL}-\sigma_{LR}\),

  • 2: \(\sigma_{RL}+\sigma_{LR}\),

  • 3: \(\sigma_{0L}-\sigma_{0R}\),

  • 4: \(\sigma_{0L}+\sigma_{0R}\).

lamep [double]#

polarization degree of the positron.

lamem [double]#

polarization degree of the electron.

costhcut [double]#

cut on \(|\cos\theta|\) for both final state particle.

e5max [double]#

cut on maximum energy of hard photon.

ome [double]#

is the parameter separating contributions from soft and hard photon Bremsstrahlung (\(\omega=ome \sqrt{s}/2\)).

Flags controlling components of the NLO EW computations#

iqed [integer]#

  • 0: disables QED corrections,

  • 1: with full QED corrections,

  • 2: only initial state QED radiation (ISR),

  • 3: initial-final QED radiation interference term (IFI),

  • 4: only final state QED radiation (FSR),

  • 5: sum of initial and final state radiation contributions [IFI+FSR],

  • 6: sum of initial state and initial-final QED interference terms [ISR+IFI],

  • 7: sum of initial and final state QED radiation contributions [ISR+FSR].

iew [integer]#

  • 0: disables weak corrections,

  • 1: enables weak corrections.

iborn [integer]#

  • 0: enables NLO corrections,

  • 1: forces LO calculation.

ifgg [integer]#

  • 1: default vacuum polarization \((1+\mathcal{F}_{\gamma\gamma}(\mathrm{NLO}))\),

  • 2: ressummed vacuum polarization \((1/[1 - \mathcal{F}_{\gamma\gamma}(\mathrm{NLO})])\).

irun [integer]#

  • 0: fixed gauge boson width,

  • 1: running gauge boson width.

gfscheme [integer]#

flag selects electroweak scheme in which the calculation is performed:

  • 0: \(\alpha(0)\)-scheme,

  • 1: \(G_{\mu}\)-scheme,

  • 2: \(\alpha(M_Z)\)-scheme.

iqedll [integer]#

  • 0: disables LL ISR QED corrections,

  • 1: \(O(alpha L)\) gamma corrections. Attention! Double counting is possible! Only for crosscheck.

  • 2: \(O(alpha^2 L^2)\) gamma corrections,

  • 3: \(O(alpha^2 L^2)\) el pair corrections,

  • 4: \(O(alpha^2 L^2)\) mu pair corrections,

  • 5: \(O(alpha^3 L^3)\) gamma corrections,

  • 6: \(O(alpha^3 L^3)\) el pair corrections,

  • 7: \(O(alpha^3 L^3)\) mu pair corrections,

  • 8: \(O(alpha^4 L^4)\) gamma corrections,

  • 9: \(sum_{n=2}^2 O(alpha^n L^n)\) corrections,

  • 10: \(sum_{n=2}^3 O(alpha^n L^n)\) corrections,

  • 11: \(sum_{n=2}^4 O(alpha^n L^n)\) corrections – best choice.

deltall [double]#

small auxiliary parameter for LL corrections calculation. The result does not depend on it.

scalell [double]#

scale at which LL corrections are calculated.

Special process parameters for hadron mode#

ibeams [integer]#

  • 1: corresponds to \(pp\) colliding beams,

  • 2: corresponds to \(p\bar p\) colliding beams.

pdfname [string]#

sets the name of the PDF set connected via LHAPDF.

pdfmember [string]#

sets a member of the PDF set.

iph [integer]#

flag controls which photon induced contributions are calculated.

  • 0: disables photon induced contributions,

  • 1: only \(\gamma\gamma\) contribution is enabled,

  • 2: both \(\gamma\gamma\) and \(\gamma q\) contributions are enabled,

  • 3: only \(\gamma q\) contribution is enabled.

iscale [integer]#

flag sets factorization scale \(Q^2\).

  • 1: \(Q^2 = S = x1*x2*ecm\),

  • 2: \(Q^2 = M_Z^2\) for NC, \(Q^2 = M_W^2\) for CC,

  • 3: \(Q^2 = M(l^+l^-)^2\).

Standard Model parameters#

alpha, gf, alphas, conhc [double]#

a list of constants and coefficients:

\(\alpha_{EM}\), \(G_{\mu}\), \(\alpha_{S}\), conversion constant from \(GeV^{-2}\) to pb.

mw, mz, mh [double]#

W, Z, Higgs boson masses.

wz, ww, wh, wtp [double]#

W, Z, Higgs and the top quark widths.

men, mel, mmn, mmo, mtn, mta [double]#

\(\nu_e\), e, \(\nu_{\mu}\), \(\mu\), \(\nu_{\tau}\), \(\tau\) lepton masses.

mdn, mup, mst, mch, mbt, mtp [double]#

d, u, s, c, b, t quark masses.

Flags controlling input/output#

explore{Born,Virt,Hard,Brdq,Ibaa,Ibaq,Ibs1,Ibs2} [boolean]#

true/false: generates new grid for corresponding branch or use existing grid.

printROOT [boolean]#

true/false: saves events in ROOT format.

printLHE [boolean]#

true/false: saves events in LHE format.