This page is still under development. Any comment is welcome.
Note: the following MC samples refer to 1998 D2 processing.
| Generator | Pertinent Features | Recommended Datasets |
| PYTHIA v5.722 | CC03 only. (No interference effects). FSR and multiphoton ISR (with P_t) are implemented. Hadronization is built-in through JETSET v7.409. m_W = 80.323. |
XS_WWPY_E189_F98_1L_D2 |
| EXCALIBUR v1.08 |
All diagrams leading to WW like final states are included. Also
NC qqqq diagrams in there. Non-massive fermions, both in phase space and in the matrix elements. m_W = 80.35. Fixed W width. Interfaced with tau polarisation. FSR is now correctly included. P_t ISR inspired by GRACE. |
XS_WWEX_E189_R98_1L_D2 (EXCALIBUR v1.01) XS_WWEX_E189_SA98_1L_D2 |
| Name | Generator | Pertinent Features | Recommended Datasets |
|
| |||
| qq(g) | PYTHIA v5.722 | See above. |
XS_ZGPY_E188_F98_1L_D2 XS_ZGPY_E188_B98_1L_D2 |
| ee(g) | BABAMC | . |
Bhabha forward (e polar angle > 9 degrees): XS_BAFO_E188_B98_1L_D2 Bhabha barrel (e polar angle >37 degrees): XS_BABA_E188_B98_1L_D2 |
| mm(g) | KORALZ v4.2 |
Can handle tt,mm,vv final states. ISR (with P_t) is implemented. Multiphoton FSR is implemented. Tau polarisation included. More than 20 tau decay modes can be generated. |
XS_MUMU_E188_R98_1L_D2 |
tt(g) | KORALZ v4.2 | See above. |
XS_KORA_E188_R98_1L_D2 |
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| |||
| 'ZZ' | PYTHIA v5.722 | Tau polarisation included. | XS_ZZPY_E189_R98_1L_D2 |
| 'Zee' | PYTHIA v5.722 | Tau polarisation included. | XS_ZEPY_E189_R98_1L_D2 |
| 'Wev' | PYTHIA v5.722 | See above. No D2 available yet. |
XS_WEPY_E189_SA98_1L_A1 |
| 4f non WW | EXCALIBUR v0.94 |
All non-WW like diagrams are available separately. In case of electrons in the final state only the region |cos_theta_e|<0.9999 is covered. See above for other features. |
llll (l.ne.e): XS_LLLL_E189_R98_1L_D2 eeqq: XS_EEQQ_E189_R98_1L_D2 mmqq: XS_MMQQ_E189_R98_1L_D2 (EXCALIBUR v1.05) ttqq: XS_TTQQ_E189_R98_1L_D2 vvqq: XS_VVQQ_E189_R98_1L_D2 eemm: XS_EEMM_E189_R98_1L_D2 eett: XS_EETT_E189_R98_1L_D2 eeee [abs(cos(teta_e))<0.98, m_ee>0.0025 Gev^2]: XS_EEEE_E189_R98_1L_D2 |
(gg)->had. (QPM) |
BDKRC | Can generate eemm, eett, eeqq(QPM) final states. Radiative corrections included. |
Unbiased sample: XS_GGQP_E184_R97_1L_E2/ C0001-20 Biased [E_t>4 GeV, E_forw/E_vis<.7]: XS_GGQP_E184_R97_1L_E2/ C0021-33 |
(gg)->had. (QCD) |
TWOGAM v1.71 | P_t cut set to 1.8 GeV. A cut to 3 GeV is imposed to detectable transverse energy. |
Unbiased sample: XS_GGQC_E184_R97_1L_E2/ C0001-62 Biased [E_t>4 GeV, E_forw/E_vis<.7]: XS_GGQC_E184_R97_1L_E2/ C0063-89 |
(gg)->had. (VDM) |
TWOGAM v1.71 | See above. |
Biased [E_t>4 GeV, E_forw/E_vis<.7]: XS_GGVD_E184_SA97_1L_E2/ C0001-28 |
(gg)->ee |
BDK | All diagrams, but no radiative corrections. |
Unbiased sample: XS_GGEE_E184_B97_1L_E2/ C0085-203 Biased sample [E_t>4 GeV]: XS_GGEE_E184_B97_1L_E2/ C0001-84 |
(gg)->mm |
BDKRC | See above. |
Biased sample [E_t>4 GeV]: XS_GGMU_E184_R97_1L_E2/ C0001-20 Biased sample [E_t>2 GeV]: XS_GGMU_E184_R97_1L_E2/ C0021-38 |
(gg)->tt | BDKRC | See above. |
Unbiased sample: XS_GGTT_E184_R97_1L_E2/ C0001-38 |
Problems in the very soft part of the data.There is an evident data/MC disagreement in low multiplicity and low E_t (P_t) region (gg interactions' region). Probably the gg generators are not able to describe the soft part of the data very well. The discrepancy is not visible after the selection but this represent a problem for the tuning of the cuts and the proper evaluation of the systematics. |
ISR with P_t.One of the desireable features (especially for 4f generators) is the correct reproduction of P_t ISR in order to improve the reconstruction of the event transverse momentum. Many efforts have been put to implement this in EXCALIBUR. Will KORALW represent the solution? |
Better understanding of divergent regions.There are sets of diagrams (like 'Zee') which lead to almost irreducible background for the semileptonic channel. This contributions are divergent (in the massless limit) when the final, non-radiating electron (positron) goes along the beam pipe (which is the most interesting situation from the physics point of view). At the moment the generation of these events is either done with non-massive fermions by setting cuts to the electron (positron) direction (EXCALIBUR), or with approximations to treat the singularity in the forward direction (PYTHIA). Further studies using different approaches (4f+massive electrons) could be helpful in understanding the real contribution of these processes.These studies could then also be used to understand data/MC discrepancy in the gg interactions' region. |