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

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

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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.

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SLIDE 1

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

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SLIDE 2

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 JP 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

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SLIDE 3

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, aµ, where a more than 3.5σ deviation

is observed from the SM prediction

  • 92% of ahad,LO

µ

is saturated by √s from threshold to 2 GeV

  • 73% of ahad,LO

µ

is saturated by e+e− → π+π− at √s < 2 GeV

  • γγ → π0, η, η′ is important for ahad,LBL

µ

  • Hadronic contributions to running α
  • mu(d) and quark /gluon condensates from QCD sum rules
  • Test of CVC by comparing e+e− and τ

S.Eidelman, BINP p.3/18

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SLIDE 4

EPS11, Grenoble July 21-27, 2011

e+e− → 3π+3π−

0.5 1 1.5 2 1 1.5 2 2.5 3 3.5 4 4.5 Ec.m. (GeV) σ(3(π+π-)) (nb)

A new dip structure around 1.9 GeV – baryonium or ρ(1900)?

S.Eidelman, BINP p.4/18

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SLIDE 5

EPS11, Grenoble July 21-27, 2011

VEPP-2000 Accelerator Complex

Machine Physics √s, MeV Lmax, 1030cm−2s−1 R L dt, pb−1 VEPP-2M 1975 – 2000 360–1400 3 ∼ 60 VEPP-2000 2010 – 2020 300–2000 100 ∼ 3000 S.Eidelman, BINP p.5/18

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SLIDE 6

EPS11, Grenoble July 21-27, 2011

VEPP-2000 Collider

Round beams: 1 × 1 bunch, ǫx = ǫy, σ∗

x = σ∗ y, νx = νy

S.Eidelman, BINP p.6/18

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SLIDE 7

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

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SLIDE 8

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

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SLIDE 9

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

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SLIDE 10

EPS11, Grenoble July 21-27, 2011

φ → K+K−, KSKL

S.Eidelman, BINP p.10/18

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SLIDE 11

EPS11, Grenoble July 21-27, 2011

Selection of 3π+3π− Events – I

50 100 150 200 250 300 350 400 450 2 4 6 8 10 12 14 16 18

Total momentum for 6 good tracks - data

50 100 150 200 250 300 350 400 450 100 200 300 400 500

Total momentum for 6 good tracks - MC

200 400 600 800 1000 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

Six Good Track Momentum vs dEdX - data

200 400 600 800 1000 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

Six Good Track Momentum vs dEdX - MC

S.Eidelman, BINP p.11/18

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SLIDE 12

EPS11, Grenoble July 21-27, 2011

Selection of 3π+3π− Events – II

hEtotv6Ngood

Entries 114 Mean

  • 11.66

RMS 30.04 Underflow Overflow Integral 113

  • 300
  • 200
  • 100

100 200 2 4 6 8 10 12 14 16

hEtotv6Ngood

Entries 114 Mean

  • 11.66

RMS 30.04 Underflow Overflow Integral 113

Total energy - 2ebeam for 6 good tracks

hEtotv6Ngood

Entries 6291 Mean

  • 5.423

RMS 26.95 Underflow Overflow Integral 6291

  • 300
  • 200
  • 100

100 200 100 200 300 400 500 600 700 800

hEtotv6Ngood

Entries 6291 Mean

  • 5.423

RMS 26.95 Underflow Overflow Integral 6291

Total energy - 2ebeam for 6 good tracks

hMism0v5Ngood

Entries 303 Mean 3.145e+04 RMS 4.694e+04 Underflow 8 Overflow Integral 278 / ndf

2

χ 67.92 / 172 Prob 1 p0 17.4 ± 235.7 p1 3.773e+03 ± 2.521e+04 p2 4.351e+03 ± 3.095e+04 p3 0.105 ± 0.522 p4 1.448e+03 ± 2.012e+04 p5 1735.4 ± 9715 p6 4.840e-07 ± 7.437e-08 p7 0.0852 ± 0.2452

  • 100
  • 50

50 100 150 200 250

3

10 × 2 4 6 8 10 12 14 16

hMism0v5Ngood

Entries 303 Mean 3.145e+04 RMS 4.694e+04 Underflow 8 Overflow Integral 278 / ndf

2

χ 67.92 / 172 Prob 1 p0 17.4 ± 235.7 p1 3.773e+03 ± 2.521e+04 p2 4.351e+03 ± 3.095e+04 p3 0.105 ± 0.522 p4 1.448e+03 ± 2.012e+04 p5 1735.4 ± 9715 p6 4.840e-07 ± 7.437e-08 p7 0.0852 ± 0.2452

Missing mass for 5 good tracks

hMism0v5Ngood

Entries 14571 Mean 2.35e+04 RMS 2.325e+04 Underflow 110 Overflow Integral 1.444e+04 / ndf

2

χ 431.2 / 129 Prob 3.225e-34 p0 327.8 ± 5496 p1 4.833e+02 ± 2.645e+04 p2 7.547e+02 ±

  • 2.326e+04

p3 0.0733 ±

  • 0.7527

p4 8.714e+01 ± 2.045e+04 p5 121.5 ± 6722 p6 2.998e-06 ±

  • 7.875e-06

p7 0.444 ± 5.048

  • 100
  • 50

50 100 150 200 250

3

10 × 200 400 600 800 1000 1200 1400

hMism0v5Ngood

Entries 14571 Mean 2.35e+04 RMS 2.325e+04 Underflow 110 Overflow Integral 1.444e+04 / ndf

2

χ 431.2 / 129 Prob 3.225e-34 p0 327.8 ± 5496 p1 4.833e+02 ± 2.645e+04 p2 7.547e+02 ±

  • 2.326e+04

p3 0.0733 ±

  • 0.7527

p4 8.714e+01 ± 2.045e+04 p5 121.5 ± 6722 p6 2.998e-06 ±

  • 7.875e-06

p7 0.444 ± 5.048

Missing mass for 5 good tracks

S.Eidelman, BINP p.12/18

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SLIDE 13

EPS11, Grenoble July 21-27, 2011

e+e− → 3π+3π− at CMD-3

Ec.m., (MeV) 1400 1500 1600 1700 1800 1900 2000 2100 Cross section, (nb) 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Good agreement and comparable precision to BABAR, A dip at 1900 MeV confirmed, baryonium or ρ(1900)?

S.Eidelman, BINP p.13/18

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SLIDE 14

EPS11, Grenoble July 21-27, 2011

Selection of e+e− → p¯ p Events – I

Average momentum (MeV) 200 400 600 800 1000 1200 1400 Total energy in calorimeter (MeV) 500 1000 1500 2000 2500

S.Eidelman, BINP p.14/18

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SLIDE 15

EPS11, Grenoble July 21-27, 2011

Selection of e+e− → p¯ p Events – II

Average momentum (MeV) 50 100 150 200 250 300 350 400 450 5 10 15 20 25 30 35 40 Average momentum (MeV) 400 600 800 1000 1200 20 40 60 80 100 120

S.Eidelman, BINP p.15/18

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SLIDE 16

EPS11, Grenoble July 21-27, 2011

Example of an e+e− → p¯ p Event

S.Eidelman, BINP p.16/18

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SLIDE 17

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

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SLIDE 18

EPS11, Grenoble July 21-27, 2011

Conclusions

  • VEPP-2000 has been successfully commissioned

with a luminosity of 2 · 1031 cm−2s−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(3π+3π−) 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 ahad,LO

µ

S.Eidelman, BINP p.18/18

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SLIDE 19

EPS11, Grenoble July 21-27, 2011

Back-up Slides

S.Eidelman, BINP p.19/18

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SLIDE 20

EPS11, Grenoble July 21-27, 2011

Cross Sections with CMD-2 at VEPP-2M

S.Eidelman, BINP p.20/18

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SLIDE 21

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