Quest for precision in hadronic cross sections at low energy: Monte Carlo tools vs. experimental data

Abstract

We present the achievements of the last years of the experimental and theoretical groups working on hadronic cross section measurements at the low-energy e (+) e (-) colliders in Beijing, Frascati, Ithaca, Novosibirsk, Stanford and Tsukuba and on tau decays. We sketch the prospects in these fields for the years to come. We emphasise the status and the precision of the Monte Carlo generators used to analyse the hadronic cross section measurements obtained as well with energy scans as with radiative return, to determine luminosities and tau decays. The radiative corrections fully or approximately implemented in the various codes and the contribution of the vacuum polarisation are discussed. ; This work was supported in part by: – European Union Marie-Curie Research Training Networks MRTN-CT-2006-035482 "FLAVIAnet" andMRTN-CT-2006- 035505 "HEPTOOLS"; – European Union Research Programmes at LNF, FP7, Transnational Access to Research Infrastructure (TARI), Hadron Physics2-Integrating Activity, Contract No. 227431; – Generalitat Valenciana under Grant No. PROMETEO/2008/069; – German Federal Ministry of Education and Research (BMBF) grants 05HT4VKA/3, 06-KA-202 and 06-MZ-9171I; – German Research Foundation (DFG): 'Emmy Noether Programme', contracts DE839/1-4, 'Heisenberg Programme' and Sonderforschungsbereich/Transregio SFB/TRR 9; – Initiative and Networking Fund of the Helmholtz Association, contract HA-101 ("Physics at the Terascale"); – INTAS project Nr 05-1000008-8328 "Higher-order effects in e+e− annihilation and muon anomalous magnetic moment"; – Ministerio de Ciencia e Innovación under Grant No. FPA2007- 60323, and CPAN (Grant No. CSD2007-00042); – National Natural Science Foundation of China under Contracts Nos. 10775142, 10825524 and 10935008; – Polish Government grant N202 06434 (2008-2010); – PST.CLG.980342 – Research Fellowship of the Japan Society for the Promotion of Science for Young Scientists; – RFBR grants 03-02-16477, 04-02-16217, 04-02-1623, 04-02- 16443, 04-02-16181-a, 04-02-16184-a, 05-02-16250-a, 06-02- 16192-a, 07-02-00816-a, 08-02-13516, 08-02-91969 and 09- 02-01143; – Theory-LHC-France initiative of CNRS/IN2P3; – US DOE contract DE-FG02-09ER41600. We thank J. Libby for useful correspondence about the luminosity measurement at CLEO-c, and A. Pich, J. Portolés, D. Gómez-Dumm, M. Jamin and Z.H. Guo for fruitful collaborations and useful suggestions related to the Tau Physics section. S. Eidelman and V. Cherepanov are grateful to the Cracow Institute of Nuclear Physics where part of this work has been performed. M. Gunia acknowledges a scholarship from the UPGOW project co-financed by the European Social Fund. F. Jegerlehner acknowledges support by the Foundation for Polish Science. ; Peer reviewed