1 / 46

Meson-Production Experiments at COSY-Jülich

Meson-Production Experiments at COSY-Jülich. Tools (1): COoler SYnchrotron COSY. WASA. (Polarized) p & d beams Electron & stochasting cooling Beam momentum: 0.30 – 3. 70 GeV/c pp  pp X ( m X  1.1 GeV/c 2 ) dd  4 He X ( m X  1.0 3 GeV/c 2 ). ANKE. p , d. 10 m.

carys
Download Presentation

Meson-Production Experiments at COSY-Jülich

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Meson-Production Experimentsat COSY-Jülich

  2. Tools (1): COoler SYnchrotron COSY WASA • (Polarized) p & d beams • Electron & stochasting cooling • Beam momentum: 0.30 – 3.70 GeV/c • pp  pp X (mX  1.1 GeV/c2) • dd  4He X (mX  1.03 GeV/c2) ANKE p, d 10 m PAX TOF ~ 340 users, 15 countries

  3. COSY Tools (2): Hadronic Interactions • + Large production cross section • + Reactions = “Isospin filters” • e.g.pp→d X (Ix = 1) • dd→4He X (Ix = 0) • – Large background  highly selective detectors!

  4. Tools (3): ANKE & WASA WASA ANKE • Forward spectrometer • Excellent K+/K−i.d. • Cluster-jet target (L~ few1031 cm-2s-1)Polarized target • Almost 4p coverage • Charged and neutral particle detection • Frozen-pellet target (L~ 1032 cm-2s-1)

  5. Precise h-mass determination 1

  6. mass: conflicting results new exp. with better knowledge of beam energy MAMI/Crystal Ball preliminary *) GEM/COSY 05 *) http://wwwa1.kph.uni-mainz.de/Bosen/archive/talks/2007/seminars/Nikolaev.pdf

  7. Measurement of the h mass at ANKE: The idea • Measurement of the two-body reaction dp→3Hehusing a ramped COSY deuteron beam •  Determine dp→3He+hreaction threshold (Q = 0) from kinematics •  Calibrate absolute beam momentum pd with a spin-resonance method

  8. Kinematics 3He momentum [MeV/c] size of kinematic ellipse determines Q value and threshold location beam momentum [MeV/c]

  9. Beam energy determination: the method • Depolarize a vertically polarized deuteron beam through an artificially induced spin resonance • induced by an external rf solenoid field • if frequency of the rf field = spin-flip resonance frequency fr→ beam depolarizes fr EDDA detector as beam polarimeter polarization [arb. units] rf-solenoid frequency [MHz]

  10. Beam energy determination: results Gd– gyromagnetic anomaly fr – spin resonance frequency f0 – beam revolution frequency (from Schottky noise) ∆p/p ≤ 6×10−5 P. Goslawski et al., subm. to PR ST-AB arXiv:0908.3103v1 [physics.acc-ph]  Expected accuracy of h mass: ∆mh ≤ 50 keV/c²

  11. Symmetry tests in h-meson decays 2

  12. h  3p0 • First WASA-at-COSY production run (April 2007) • 4 days data taking, pp→pph, L=1031 cm-2s-1, Tp=1.4 GeV C.Adolph et al., PLB 677, 24 (2009) [arXiv:0811.2763 [nucl-ex] ] 1.2 · 105 events a = –0.027 ± 0.008(stat) ± 0.008(syst) analysis: P.Vlasov p.vlasov@fz-juelich.de

  13. h 3p0: status of experiment vs. theory experiment ↔ PT calculations (up to NNLO)  strong discrepancy

  14. Towards rare h decays at WASA • pd→ 3He h • 4 weeks data taking (Sept. 2008) • L= 2.5·1031 cm-2s-1, Q=60 MeV, Tp=1000 MeV • 107h mesons on disk / all decay channels • 8 more weeks in Aug./Sept. 2009 • Channels being analyzed: p+p–g (BR=4.6%) e+e–g (6.8·10-3) p+p–e+e– (4.2·10-4) e+e–p0 (<4·10-5) e+e–e+e– (<6.9·10-5) e+e– (<7.7·10-5) 17 h data taking (3% of total statistics) Trigger on 3He (no further cuts)

  15. h→e+e–e+e– F(q1², q2²) • Determination of the h transition form factor F(q1², q2²) • Study off-shell structure of the hgg vertex • Input for calculation of muon anomalous magnetic moment • Measure shape of M(e+e–) [= q²(g*)] distribution • Branching ratio • Exp.: < 6.9 · 10-5 • Theory: ~ 6 · 10-5 see e.g. J.Bijnens and J.Gasser, Phys. Scripta T99 (2002) 34 [arXiv:hep-ph/0202242] R.R. Akhmetshin et al. [CMD-2 Collaboration] PL B 501, 191 (2001) [arXiv:hep-ex/0012039]

  16. h→e+e–e+e– at WASA analysis: L.Yurev l.yurev@fz-juelich.de COSY beam Central „Mini Drift Chamber“ XY projection currently 15 candidate events (from 4 weeks of pd→ 3He h data)

  17. Rare h decays: beyond Standard Model? • Example: h→ e+e– • WASA’s “golden channel” • SM prediction: BR = (5.8 ±0.2)·10–9 • any larger BR hints at physics beyond SM • current upper limit: BR < 2.7·10–5 • WASA ≥2010pp→ pph • ~20 times larger cross section than pd→ 3Heh • larger background ⇒ more selective on-line trigger  goal 1010 h/year D. Gómez Dumm and A. Pich, PRL 80, 4633 (1998) WASA/CELSIUS M. Berlowski et al., PR D 77 (2008) 032004.

  18. 2p0 production 3

  19. pn→ dp0p0 Talk by M.Bashkanov Tuesday 02:20pm • Narrow structure in √s distribution! • Not seen in isospin-related reactions Preliminary pn → d p0p0 pp → d p+p0

  20. Kaon-pair production 4

  21. p/d-induced KK production: World data set total cross section, nb pp → ppK+K– pp → dK+K0 pn → dK+K– pd → 3HeK+K– dd → 4HeK+K– ●■▲ - COSY ANKE, COSY-11, MOMO ○ - DISTO test fordd → 4He f0(980) ↳ a0(980) excess energy, MeV

  22. x 1011 !! 5 pb dd4He K+K– X.Yuan et al., EPJ A in print DOI 10.1140/epja/i2009-10849-7 arXiv:0905.0979 [nucl-ex] ~5 events cross section for the “isospin filter” dd→4HeX is extremely small  better @BES (J/y →ff0→fa0→f(p0h) )

  23. KK production: Interpretation pp (→ pK+L(1405)) → ppK+K– pp→ pK+L(1405) → pK+p0S0 Analysis of the coupled p0S0K–p final states • Resonances below KK [a0/f0(980)] and KN [L(1405)] thresholds C. Wilkin arXiv:0812.0098  Driven through L(1405) production Close-to-threshold regime: limited phase space & strong FSI

  24. Scattering length and effective range for pp: K–p scattering length Our simple FSI parameterization (here pp→ppK+K–) Also used for pp→pph by: U.-G.Meißner et al. EPJ A 4 (1999) 259 K+K– FSI: 2nd order effect K+p interaction: neglected

  25. Simple FSI ansatz: Successful! pp→ppK+K– (Q=51 MeV) pp→dK+K0 (Q=104 MeV) • Describes all data up to 100 MeV excess energy Strong dK0 FSI visible

  26. K+K– K0K0 KK invariant mass distributions • Low-mass enhancement K+K– K0K0 thresholds

  27. Coupled-channel effects in KK production • The model: virtual K0K0 production followed by a K0K0→ K+K– conversion • Enhancement factor: KK production amplitudes (I=0,1) elastic scattering ∝ K0K0⇌ K+K– scattering length • K-matrix formalism with assumptions: • constant matrix elements • s-wave scattering • isospin invariance broken only by K0–K± mass difference A.Dzyuba et al., PLB 668, 315-318 (2008) arXiv:0807.0524 [nucl-ex]

  28. Coupled-channel effects in KK production • Kaon pairs are dominantly produced in isospin zero configuration pp→ppK+K– K0K0threshold A.Dzyuba et al., PLB 668, 315-318 (2008) arXiv:0807.0524 [nucl-ex]

  29. Summary • COSY with ANKE & WASA (and others) • Symmetry & SM tests in hadronic interactions • High precision experiments utilizing spin • Antikaon-Nucleon systems

  30. Thank you for your attention

  31. Spare foils

  32. Tools (1): COoler SYnchrotron COSY-Jülich

  33. WASA - Wide Angle Shower Apparatus

  34. ANKE – Apparatus for detection of Nucleon and Kaon Ejectiles

  35. TOF – Time Of Flight spectrometer Target Tracking Detectors

  36. Internal targets at COSY Cooled Laval nozzle Operation principle: Focussing and defocussing of hydrogen or deuterium hyperfine states Condensation point Virtual target point Skimmer Pellet Polarized (ABS) Cluster jet

  37. Some words about the h meson • Simple QM characterization: • All important quantum numbers are zero: spin, isospin, el.charge, strangeness, charm, bottom, baryon & lepton number • Parity: P|h> = –1|h>; charge conjugation: C|h> = +1|h> • All first order strong, electro-magn., weak decays are forbidden •  Study higher order or weak processes •  Test the symmetries that forbid first order decays • Example: h → 3p: • Forbidden by isospin conservation • Test ground for EFTs of QCD • Potentially delivers quark mass ratios see e.g. J.Bijnens and J.Gasser, Phys. Scripta T99 (2002) 34 [arXiv:hep-ph/0202242]

  38. pp→ pph large cross section:s=10 µb at Q=60 MeV ideal for rare decays high background direct multi-pion productions(2p0)/s(h) ~ 20 trigger on specific h decays ideal for:h → 3p0 , e+e–p+p– , e+e–e+e– , e+e– pd→ 3He h lower cross section:s=0.4 µb less multi-pion backgrounds(2p0)/s(h) ~ 1 unbiased trigger (all h decays) clean h tagging via 3He i.d. ideal for:h → p+p–p0 , p0gg Hadronic hproduction: complementary reactions

  39. Quark-mass ratios from h 3p “Leutwyler’s ellipse” H.Leutwyler, hep-ph/9609465

  40. Rare h decays: possible symmetry tests with WASA • Many current upper limits can be improved C. Amsler et al. (Particle Data Group), PLB 667, 1 (2008)

  41. h→p+p–p0 with WASA • another test of PT / up-down quark-mass difference • ~5·105 events expected, incl. 2009 (KLOE: 1.3·106) • analysis in progress G(3p0)/G(p+p–p0), Dalitz plot etc. • Other channels being analyzed: p+p–g (BR=4.6%), e+e–g (6.8·10-3), p+p–e+e– (4.2·10-4), e+e–p0(<4·10-5), e+e–e+e– (<6.9·10-5), e+e– (<7.7·10-5) analysis: P.Adlarson patrik.adlarson@fysast.uu.se

  42. Sensitivity of WASA *) conservative estimate; factor 2-3 more expected

  43. p0 h ga0KK gf0KK gf0KK ga0KK a0 f0 a00(980) – f0(980) mixing: Kaon loops Enhanced mixing by “Kaon loops“ K0 K+ a0 a0 f0 f0 L =  K0 _ K– a mK+ + mK- 2mK0 8 MeV d d CSB amplitude “normal“ IV o(1%) (Product of mixing amplitude L and f0 productionoperator)2 N.N.Achasov et al., PL B 88, 367 (1979)

  44. pd→ 3Heh close to threshold • Total cross section reaches maximum within Q = 0.5 MeV! PRL 98, 242301 (2007)) PLB 649, 258 (2007))

  45. Sensitive observables • KN FSI expected to be small • K and K have the same mass → kinematic effects negligible

More Related