Glasgow, October 25, 2007 Results on e+e- annihilation from CMD2 in addition to SND G.V.Fed

Glasgow, October 25, 2007 Results on e+e- annihilation from CMD2 in addition to SND G.V.Fed

Glasgow, October 25, 2007 Results on e+e- annihilation from CMD2 in addition to SND G.V.Fed

Crowe, Herb, Operations Manager has reference to this Academic Journal, PHwiki organized this Journal Glasgow, October 25, 2007 Results on e+e- annihilation from CMD2 in addition to SND G.V.Fedotovich in addition to S.I.Eidelman Budker Institute of Nuclear Physics Novosibirsk On behalf of CMD-2 in addition to SND collaborations VEPP-2M collider VEPP-2M collider: 0.36-1.4 GeV in c.m., L21030/cm2s at 1 GeV Integrated Luminosity collected by CMD-2 in addition to SND: 70 pb-1 collected in 1993-2000 compared to 6 pb-1 in Orsay in addition to Frascati at 1.4 < 2E < 3 GeV What can we learn 1. Detail study of exclusive processes: e+e- (2 – 7)h, h = ,,K,p, Test of models in addition to input to theory (ChPT, MVD, QCD, ) Properties of vector mesons (’,’,’, ) Search as long as hybrids (qqg in addition to glueballs) Test of CVC relations between e+e- in addition to -lepton Interactions of light (u, d, s) quarks 2. High precision determination of R at low energies in addition to fundamental quantities (g – 2)/2 (M²z) QCD sum rules (s, quark in addition to gluon condensates) Kentucky State University US

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CMD-2 in addition to SND detectors 1 –vacuum chamber, 2 – drift chambers, 3 – scintillation counter, 4 – light guides, 5 – PMT, 6 – NaI(Tl) crystals, 7 – VPT, 8 – iron absorber, 9 – muon range system based on streamer tubes, 10 – iron plates, 11 – scintillation counters 1 – vacuum chamber, 2 – drift chamber, 3 – Z-chamber, 4 – superconducting solenoid, 5 – compensating magnets, 6 – BGO end cap calorimeter, 7 – CsI(Tl,Na) calorimeter, 8 – muon system, 9 – magnet yoke Some features of experiments with CMD-2 in addition to SND Large data sample due to high integrated luminosity in addition to large detectors acceptance (calorimetry 0.94) Multiple scan of the same energy range to avoid possible systematics: step (2E) = 10 MeV in the continuum in addition to 1 MeV near in addition to peaks Absolute calibration of the beam energy using the resonance depolarization method negligible systematic error from an uncertainty in the energy measurement Good space in addition to energy resolutions lead to small background Redundancy – unstable particles detected via different decay modes (º2, e+e-; 2, +-0, 30; ) Detection efficiencies in addition to calorimeter response are studied by using “pure” experimental data samples rather than MC events (about 20 million in addition to meson decays have been used) How cross-sections are measured

Selection of e+e- +- at CMD-2 e// separation using particles momentum in DC can measure N()/N(e) in addition to compare to QED < 0.6 GeV Momentum Energy >0.6 GeV N()/N(e) is fixed according to QED e// separation using energy deposit. in CsI calorimeter Momentum Energy Likelihood minimization: Selection of e+e- +- at SND Event separation is based on neural network: 1 output parameter – Re/ 2 hidden layers 20 neurons each 7 input parameters: energy deposition in each layer as long as both clusters in addition to polar angles Distribution on separation parameter Example of CMD-2 in addition to SND events e+e-+- in CMD-2 e+e-K+K- in SND

Pion as long as m-factor (CMD-2) ~ 9105 +- events Comparison of CMD-2(95) in addition to CMD-2(98) (95-98)0.7%±0.5% Pion as long as m-factor (SND) 3.2% 1.3% Systematic error ~ 8105 +- events

Comparison of CMD-2 in addition to SND s<0.55 GeV 0.6

CMD-3 detector 1 – beam pipe, 2 – drift chamber, 3 – BGO, 4 – Z – chamber, 5 – s.c. solenoid, 6 – LXe, 7 – CSI, 8 – yoke , 9 – VEPP s.c. solenoid Conclusions Despite decades of experiments, precise studies of e+e annihilation into hadrons at low energies are still interesting in addition to can provide a lot of important in as long as mation Experiments at VEPP-2M with two detectors CMD-2 in addition to SND significantly improved the accuracy of hadronic cross sections below 1.4 GeV Progress is particularly important as long as e+e-+-, where systematic uncertainty is 1% or even better Based on data from VEPP-2M together with ISR data obtained at KLOE in addition to BaBar the error of aµ was significantly decreased matching the experimental accuracy aµ(exp)- aµ(SM) differs from 0 by 3.3 necessitating more accurate independent measurements In a few years new precision data from CMD-3 in addition to SND working at VEPP-2000 are expected as well as with ISR at DAFNE in addition to B-factories

Crowe, Herb Operations Manager

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