First Results from the CMD-3 Detector Simon Eidelman Budker - PowerPoint PPT Presentation

EPS11, Grenoble July 21-27, 2011 First Results from the CMD-3 Detector Simon Eidelman Budker Institute of Nuclear Physics SB RAS and Novosibirsk State University, Novosibirsk, Russia Outline 1. Motivation 2. Experiment 3. First results 4. Conclusions S.Eidelman, BINP p.1/18

EPS11, Grenoble July 21-27, 2011 Physics at VEPP-2000 – I • VEPP-2000 – e + e − collider in Novosibirsk, √ s from threshold to 2 GeV • Total and exclusive cross sections of e + e − → hadrons: 1. Interactions of light quarks 2. Spectroscopy of light vector mesons – ρ ′ , ω ′ , φ ′ 3. Study of mesons with other J P C 4. F/f measurement in various two-body channels 5. p ¯ p, n ¯ n production near threshold 6. Search for various exotics S.Eidelman, BINP p.2/18

EPS11, Grenoble July 21-27, 2011 Physics at VEPP-2000 – II Implications of low energy cross sections for various fundamental quantities: • Muon anomalous magnetic moment, a µ , where a more than 3 . 5 σ deviation is observed from the SM prediction is saturated by √ s from threshold to 2 GeV • 92% of a had , LO µ is saturated by e + e − → π + π − at √ s < 2 GeV • 73% of a had , LO µ • γγ → π 0 , η, η ′ is important for a had , LBL µ • Hadronic contributions to running α • m u ( d ) and quark /gluon condensates from QCD sum rules • Test of CVC by comparing e + e − and τ S.Eidelman, BINP p.3/18

EPS11, Grenoble July 21-27, 2011 e + e − → 3 π + 3 π − σ (3( π + π - )) (nb) 2 1.5 1 0.5 0 1 1.5 2 2.5 3 3.5 4 4.5 E c.m. (GeV) A new dip structure around 1.9 GeV – baryonium or ρ (1900)? S.Eidelman, BINP p.4/18

EPS11, Grenoble July 21-27, 2011 VEPP-2000 Accelerator Complex √ s , MeV L max , 10 30 cm − 2 s − 1 L dt , pb − 1 R Machine Physics VEPP-2M 1975 – 2000 360–1400 3 ∼ 60 VEPP-2000 2010 – 2020 300–2000 100 ∼ 3000 S.Eidelman, BINP p.5/18

EPS11, Grenoble July 21-27, 2011 VEPP-2000 Collider Round beams: 1 × 1 bunch, ǫ x = ǫ y , σ ∗ x = σ ∗ y , ν x = ν y S.Eidelman, BINP p.6/18

EPS11, Grenoble July 21-27, 2011 Luminosity at VEPP-2000 Design luminosity should be achieved after the new injection complex is commissioned in 2012 S.Eidelman, BINP p.7/18

EPS11, Grenoble July 21-27, 2011 CMD-3 Detector 1 Beam pipe 2 Drift chamber 3 BGO calorimeter 4 Z chamber 5 SC solenoid 6 LXe calorimeter 7 CsI calorimeter 8 Flux return 9 LHe supply 10 Vacuum pumpdown 11 SC focusing magnets S.Eidelman, BINP p.8/18

EPS11, Grenoble July 21-27, 2011 Data Taking • Two scans (up and down) were performed from the φ meson to 2 GeV with a step of 25 MeV and ∼ 500 nb − 1 per point • A step was smaller near the p ¯ p threshold • φ meson, 1050, 1075, 1100, 1125, . . . , 1800, 1825, 1850, 1870, 1890, 1900, 1925, 1950, 1975, 2000 • 56 points ⇒∼ 22 pb − 1 • 15 points at the φ meson from 1010 to 1034 MeV, 1 . 9 pb − 1 in total for detector studies and software tests S.Eidelman, BINP p.9/18

EPS11, Grenoble July 21-27, 2011 φ → K + K − , K S K L S.Eidelman, BINP p.10/18

EPS11, Grenoble July 21-27, 2011 Selection of 3 π + 3 π − Events – I Six Good Track Momentum vs dEdX - data Total momentum for 6 good tracks - data 20000 18 18000 16 16000 14 14000 12 12000 10 10000 8 8000 6 6000 4 4000 2 2000 0 0 0 50 100 150 200 250 300 350 400 450 0 200 400 600 800 1000 Six Good Track Momentum vs dEdX - MC Total momentum for 6 good tracks - MC 20000 500 18000 16000 400 14000 12000 300 10000 8000 200 6000 4000 100 2000 0 0 0 50 100 150 200 250 300 350 400 450 0 200 400 600 800 1000 S.Eidelman, BINP p.11/18

EPS11, Grenoble July 21-27, 2011 Selection of 3 π + 3 π − Events – II hMism0v5Ngood hMism0v5Ngood Total energy - 2ebeam for 6 good tracks hEtotv6Ngood hEtotv6Ngood Missing mass for 5 good tracks Entries Entries 303 303 Entries Entries Mean Mean 3.145e+04 3.145e+04 114 114 RMS RMS 4.694e+04 4.694e+04 Mean Mean -11.66 -11.66 Underflow Underflow 8 8 16 16 Overflow Overflow 0 0 RMS RMS 30.04 30.04 Integral Integral 278 278 Underflow Underflow 0 0 χ χ 2 2 / ndf / ndf 67.92 / 172 67.92 / 172 14 14 Prob Prob 1 1 Overflow Overflow 0 0 ± ± p0 p0 235.7 235.7 17.4 17.4 12 12 p1 p1 2.521e+04 2.521e+04 ± ± 3.773e+03 3.773e+03 Integral Integral 113 113 ± ± p2 p2 3.095e+04 3.095e+04 4.351e+03 4.351e+03 ± ± 10 10 p3 p3 0.522 0.522 0.105 0.105 ± ± p4 p4 2.012e+04 2.012e+04 1.448e+03 1.448e+03 ± ± p5 p5 9715 9715 1735.4 1735.4 8 8 ± ± p6 p6 7.437e-08 7.437e-08 4.840e-07 4.840e-07 ± ± p7 p7 0.2452 0.2452 0.0852 0.0852 6 6 4 4 2 2 × 3 10 0 0 -300 -200 -100 0 100 200 -100 -50 0 50 100 150 200 250 hMism0v5Ngood hMism0v5Ngood Total energy - 2ebeam for 6 good tracks hEtotv6Ngood hEtotv6Ngood Missing mass for 5 good tracks Entries Entries 14571 14571 Entries Entries 6291 6291 Mean Mean 2.35e+04 2.35e+04 RMS RMS 2.325e+04 2.325e+04 Mean Mean -5.423 -5.423 Underflow Underflow 110 110 1400 800 RMS RMS 26.95 26.95 Overflow Overflow 0 0 Integral Integral 1.444e+04 1.444e+04 Underflow Underflow 0 0 χ χ 2 2 700 1200 / ndf / ndf 431.2 / 129 431.2 / 129 Overflow Overflow 0 0 Prob Prob 3.225e-34 3.225e-34 ± ± p0 p0 5496 5496 327.8 327.8 600 Integral Integral 6291 6291 1000 ± ± p1 p1 2.645e+04 2.645e+04 4.833e+02 4.833e+02 ± ± p2 p2 -2.326e+04 -2.326e+04 7.547e+02 7.547e+02 500 ± ± p3 p3 -0.7527 -0.7527 0.0733 0.0733 800 ± ± p4 p4 2.045e+04 2.045e+04 8.714e+01 8.714e+01 ± ± p5 p5 6722 6722 121.5 121.5 400 ± ± p6 p6 -7.875e-06 -7.875e-06 2.998e-06 2.998e-06 600 ± ± p7 p7 5.048 5.048 0.444 0.444 300 400 200 200 100 3 × 10 0 0 -100 -50 0 50 100 150 200 250 -300 -200 -100 0 100 200 S.Eidelman, BINP p.12/18

EPS11, Grenoble July 21-27, 2011 e + e − → 3 π + 3 π − at CMD-3 Cross section, (nb) 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 1400 1500 1600 1700 1800 1900 2000 2100 Ec.m., (MeV) Good agreement and comparable precision to BABAR, A dip at 1900 MeV confirmed, baryonium or ρ (1900)? S.Eidelman, BINP p.13/18

EPS11, Grenoble July 21-27, 2011 Selection of e + e − → p ¯ p Events – I Total energy in calorimeter (MeV) 2500 2000 1500 1000 500 0 0 200 400 600 800 1000 1200 1400 Average momentum (MeV) S.Eidelman, BINP p.14/18

EPS11, Grenoble July 21-27, 2011 Selection of e + e − → p ¯ p Events – II 40 120 35 100 30 80 25 20 60 15 40 10 20 5 0 0 0 50 100 150 200 250 300 350 400 450 400 600 800 1000 1200 Average momentum (MeV) Average momentum (MeV) S.Eidelman, BINP p.15/18

EPS11, Grenoble July 21-27, 2011 Example of an e + e − → p ¯ p Event S.Eidelman, BINP p.16/18

EPS11, Grenoble July 21-27, 2011 σ ( e + e − → p ¯ p ) is consistent with that of BABR and older measurements S.Eidelman, BINP p.17/18

EPS11, Grenoble July 21-27, 2011 Conclusions • VEPP-2000 has been successfully commissioned with a luminosity of 2 · 10 31 cm − 2 s − 1 achieved • Two detectors, SND and CMD-3, are taking data, we start understanding their performance • The integrated luminosity collected between 1 and 2 GeV already exceeds the one previously achieved in direct scans with precision close to BABAR • CMD-3 measures σ (3 π + 3 π − ) and confirms a dip at 1900 MeV • About 2000 events of e + e − → p ¯ p near threshold observed • In a few years we hope to measure σ ( e + e − → hadrons) with high accuracy and significantly improve the precision of a had , LO µ S.Eidelman, BINP p.18/18

EPS11, Grenoble July 21-27, 2011 Back-up Slides S.Eidelman, BINP p.19/18

EPS11, Grenoble July 21-27, 2011 Cross Sections with CMD-2 at VEPP-2M S.Eidelman, BINP p.20/18

EPS11, Grenoble July 21-27, 2011 S.Eidelman, BINP p.21/18