the e+e- Collider VEPP-2000 Sergey Serednyakov Novosibirsk State - - PowerPoint PPT Presentation

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Nov 11, 2023 203 likes •523 views

Light Hadron Production in Experiments with SND Detector at the e+e- Collider VEPP-2000 Sergey Serednyakov Novosibirsk State University Budker Institute of Nuclear Physics 13 th workshop on meson production, properties and interaction Cracow,

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Light Hadron Production in Experiments with SND Detector at the e+e- Collider VEPP-2000

Sergey Serednyakov

Novosibirsk State University Budker Institute of Nuclear Physics

13th workshop on meson production, properties and interaction Cracow, Poland, 29 may – 3 June, 2014

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BINP, Novosibirsk

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Outline

  • 1. Experiment
  • 2. e+e- -> mesons
  • 3. e+e- -> nucleons
  • 4. Conclusions

Meson 2014, 29.05-3.06 2014

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VEPP-2000 complex , in operation since 2010

VEPP-2000: revolut.frequency – 12 MHz current – 0.2 A beam length – 3.3 см energy spread – 0.7 МэВ L ≃ 1.1032 at 2E=2.0 ГэВ L=2.1031cm-2s-1 at 2E=1.0 ГэВ Meson 2014, 29.05-3.06 2014

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5 11.09.2013 PhiPsi2013 5

SND CMD-3 VEPP-2000

Meson 2014, 29.05-3.06 2014

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SND, in operation since 1995

  • 1 – beam pipe, 2 – tracking system,
  • 3 – aerogel cherenkov counter ,
  • 4 – NaI(Tl) crystals, 5 – phototriodes,
  • 6 – iron muon absorber, 7–9 –
  • muon detector, 10 – focusing

solenoids. NIM A449 (2000) 125-139

Meson 2014, 29.05-3.06 2014

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SND

Meson 2014, 29.05-3.06 2014

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Experiments 2010 - 2012

Experiment/year (1.05  2.0 GeV) Integrated luminosity s > 1.88 GeV MHAD 2010 5 pb-1 71 nb-1 MHAD 2011 25 pb-1 3.8 pb-1 MHAD 2012 17 pb-1 4.9 pb-1 Total 47pb-1 8.8 pb-1

Experiment 2013

Energy region (s, GeV) Integrated luminosity, pb -1  -  region, pb -1  - meson region, pb-1  - meson region, pb-

1

non- resonant, pb-1 0.321.06 32 15.5 3.5 7.5 5.5

Meson 2014, 29.05-3.06 2014

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e+e→ ωπ0 → π0π0γ (1)

  • Systematic error: 3.4%
  • (2E<1.55 GeV)

CVC test: SND : Br(--)= (1.96±0.02±0.10)% PDG: Br(--) = (1.95±0.08)%

(arXiv:1303.5198[hep-ex]) Phys.Rev. D88 (2013) 054013 Fit: ρ(770), ρ′(1450), ρ(1700) Meson 2014, 29.05-3.06 2014

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e+e→ ωπ0 → π0π0γ (2)

(Transition form factor γ*ωπ0, F)

(0+-)

Solid line – from cross section fit with ρ(770), ρ′(1450), ρ(1700), dashed line – ρ(770) contribution.

|F(q2)/ F(0)|2

(arXiv:1303.5198[hep-ex]) Phys.Rev. D88 (2013) 054013 Meson 2014, 29.05-3.06 2014

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e+e- -> K+ K-,

New SND measurement after Babar Aerogel Cherenkov

  • -- kaon ID

Meson 2014, 29.05-3.06 2014

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e+e- -> + 

Beginning of the analysis, 5 pb-1 Meson 2014, 29.05-3.06 2014 Very preliminary

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e+e→ π+π-π0

  • Systematic: ~5%

Contributions - (783), ′(1420), (1650).

Close to the end of analysis The most precise measurement !

Only half of statistics

Meson 2014, 29.05-3.06 2014

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e+e→ ηπ+π

  • Systematic error: 4.7%
  • (1450–1700 MeV)

Fit: ρ(770), ρ′(1450), ρ(1500) CVC test: SND : Br(--0)= (0.188+0.058-0.057)% PDG: Br(--0) = (0.139±0.01)% Ready to submit to journal Meson 2014, 29.05-3.06 2014

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e+e→ ηK+K

Very preliminary Meson 2014, 29.05-3.06 2014

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e+e→ π+π-π0π0

  • The bump comes from ρ(770),

ρ′(1450), ρ(1700).

ωπ0 non-ωπ0

Main feature – many intermediate states: ωπ0, a1π, ρππ, ρ+ρ-, ρf0.

  • Systematics  10%

Close to the end of analysis Meson 2014, 29.05-3.06 2014

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e+e→ π+π-π0 ( >2 )

f ‘(1680)

(783)

f (1020)

very preliminary first measurement Meson 2014, 29.05-3.06 2014

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e+e– → ηγ → 7γ,

first measurement for s >1.4GeV)

Photon recoil energy

MC MC

f(1680)

(1450)

(770), (782) , f(1020)

Summary fit Evidence of magnetic dipole decays of excited vector mesons The SND data are described By r(1450) and f(1680) states arXiv:1312.7078 [hep-ex] Submitted to PRD Meson 2014, 29.05-3.06 2014

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e+e- → NN cross section

         + +  

 +

) cos 1 ( 4 ) cos 1 ( 4 ) (

2 2 2 2 2 2 2 2 2

    

E B M

G m m G m C B B e e

  / ), 1 /(   

y e y c

y

        +  

 + 2 2 2 2 2 2

2 3 4 ) (

E B M

G m m G m C B B e e    

Effective form factor

2 2 2 2 2

4 , 2 / 1 1 2 /

B E M

m m G G F  + +    

At threshold : s=4mB

2 → |GE| = |GM| = |F|

Asymptotic prediction: F(+∞) = -F(-∞ ) ~ 1/s2 Differential cross section: Total cross section: Two measurable values: 1 – effective FF, 2 – GE/GM C for protons : C=1 for neutrons Meson 2014, 29.05-3.06 2014

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e+e- →pp, SND  systemat. ~0.05 nb

Meson 2014, 29.05-3.06 2014 T.G. preliminary

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Cos  , e+e-→ pp, SND

Ebeam=960 – 1000 MeV GE/GM= 1.64  0.26 Preliminary Babar :

GE/GM= 1.42  0.09

Second measurement after Babar, confirmed Babar Meson 2014, 29.05-3.06 2014

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e+e- nn

nn candidate event, Ebeam=950MeV Meson 2014, 29.05-3.06 2014

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e+e- nn, SND

preliminary Second measurement after FENICE (1998) e+e- -> n anti-n

aver = 0.8+-0.2 nb

Meson 2014, 29.05-3.06 2014

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Neutron effective FF Proton and neutron FFs

2 2 2 2

4 , 2 / 1 1 2 /

N E M

m s G G F  + +    

Effective form factor: Preliminary Neutron and proton form factors Meson 2014, 29.05-3.06 2014

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Cos  , |GE/GM|, e+e-→ nn, SND

Meson 2014, 29.05-3.06 2014 Monte Carlo Data & Fit GE/GM>0, 90% CL

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Compensation effect in total e+e- -> hadron cross section at the nucleon threshold

  • Negative jump in e+e->6
  • Positive jump in e+e N anti-N
  • No jump in total cross section
  • No explanation, why in 6 ..

arXiv:1402.5225v1 [hep-ph] 21 Feb 2014

Meson 2014, 29.05-3.06 2014

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List of analysis, E=1.05 – 2 GeV 1*. e+e→ ωπ0 → π0π0γ 2-. e+e- -> K+K- 3-. e+e- -> + 

  • 4. e+e→ π+π-π0
  • 5. e+e→ ηπ+π

6-. e+e- -> K+K-

  • 7. e+e→ π+π-π0π0

8-. e+e→ π+π-π0 9*. e+e– → ηγ → 7γ

  • 10. e+e- -> p anti-p
  • 11. e+e- -> n anti-n

12*. e+e->6 * N anti-N

Meson 2014, 29.05-3.06 2014

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Possible applications of VEPP-2000 data 1. g-2

2. em (s=MZ

2)

  • 3. CVC ( e+e- -> )
  • 4. V * -> ’, ’, f’, …

5.

Meson 2014, 29.05-3.06 2014

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Conclusions

  • 1. VEPP-2000 e+e- collider since 2011 had accumulated

~70 inv.pb data with each SND and CMD-3 detectors in the range E=0.3 – 2 GeV. First results are published.

  • 2. At SND the data analysis on meson and nucleon production

is going on. The results for more than 10 processes are presented at MESON 2014 Conference.

  • 3. After VEPP-2000 upgrade in 2015 the data taking runs

will be resumed with the goal of ~ 1 inv.fb of integrated luminosity.

  • 4. We hope to reach about ~3-5 % accuracy for the most of

e+e- -> hadrons cross sections. Meson 2014, 29.05-3.06 2014

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Thank you for attention