Review of ISR physics at BABAR

Transcription

1 Review of ISR physics at BABAR Konrad Griessinger on behalf of the BABAR Collaboration Institute for Nuclear Physics Mainz University Hadronic Physics with Lepton and Hadron Beams, Jefferson Lab, September 217 K. Griessinger (U Mainz) ISR physics at BABAR September / 23

2 ISR hadronic cross sections at BABAR cross sections, nb π + π γ π + π π π + π π π preliminary π + π π + π π + π π + π π 2π + 2π 2π 3π + 3π + K K γ + + K K K K K + K π K + K π π + K K π + π K + K π + π π + K K π + π π + π K S K L K S K L π + π K K + π + S ± K S K π η ± K π π S K + K S K S K K K S K S π + π + ηk K (notφ) + ηk K π + π + ηπ π + ηπ π π + π ppbar ± ± E, GeV as of end 216, courtesy of F. Ignatov K. Griessinger (U Mainz) ISR physics at BABAR September / 23

3 Introduction The contributions to a µ and its uncertainty µ = g µ e 2m s (g µ 2)/2 a µ = (Dirac equation) K. Griessinger (U Mainz) ISR physics at BABAR September / 23

4 Introduction The contributions to a µ and its uncertainty e µ = g µ 2m s (g µ 2)/2 =: aµ SM = aµ QED + aµ weak + aµ hadronic K. Griessinger (U Mainz) ISR physics at BABAR September / 23

5 Introduction The contributions to a µ and its uncertainty γ e µ = g µ 2m s (g µ 2)/2 =: aµ SM = aµ QED + aµ weak + aµ hadronic B µ + µ QED K. Griessinger (U Mainz) ISR physics at BABAR September / 23

6 Introduction The contributions to a µ and its uncertainty e µ = g µ 2m s (g µ 2)/2 =: aµ SM = aµ QED + aµ weak + aµ hadronic B B γ γ µ + µ µ + µ QED weak K. Griessinger (U Mainz) ISR physics at BABAR September / 23

7 Introduction The contributions to a µ and its uncertainty e µ = g µ 2m s (g µ 2)/2 =: aµ SM = aµ QED + aµ weak + aµ hadronic B B B γ γ γ µ + µ µ + µ µ + µ q QED weak q hadronic K. Griessinger (U Mainz) ISR physics at BABAR September / 23

8 Introduction The contributions to a µ and its uncertainty e µ = g µ 2m s (g µ 2)/2 =: aµ SM = aµ QED + aµ weak + aµ hadronic Contribution [ 1 1 ] Uncertainty [ 1 1 ] QED [1] weak [8] hadronic VP [5, 11] hadronic LbL [1, 4] theory total Experiment E821 [14] ExperimentTheory K. Griessinger (U Mainz) ISR physics at BABAR September / 23

9 Introduction Discrepancy between SM prediction and direct measurement from Eur.Phys.J., C71:1515, 211 [5]. HMNT 7 (e + e based) 285 ± 51 JN 9 (e + e ) 299 ± 65 Davier et al. 9/1 (τbased) 157 ± 52 Davier et al. 9/1 (e + e ) 312 ± 51 Davier et al. 9/2 (e + e w/ BABAR) 255 ± 49 HLMNT 1 (e + e w/ BABAR) 259 ± 48 DHMZ 1 (τ newest) 195 ± 54 DHMZ 1 (e + e newest) 287 ± 49 BNLE821 (world average) ± 63 BNLE a µ a µ exp 1 11 Just a fluctuation? 3σ effect, thus reduction of uncertainties necessary! K. Griessinger (U Mainz) ISR physics at BABAR September / 23

10 Introduction Connection between a µ and σ had aµ had = 1 4π 3 mπ 2 1 4m2 e s 1 + 2m2 e s K µ (s) σ e + e had(s)ds Kernel function cross section K. Griessinger (U Mainz) ISR physics at BABAR September / 23

11 Introduction ± ± + ± ± + π + π Connection between a µ and σ had aµ had = 1 4π 3 mπ 2 1 4m2 e s 1 + 2m2 e s K µ (s) σ e + e had(s)ds cross sections, nb Courtesy of F. Ignatov π + π γ π + π π π + π π π preliminary π + π π + π π + π π + π π 2π + 2π 2π 3π + 3π K K γ K K K K K + K π K + K π π K K π + π K + K π + π π K K π + π π + π K S K L K S K L π + π K K + π + S K S K π η K π π S K K S K S K K K S K S π + π ηk K (notφ) ηk K π + π ηπ π ηπ π ppbar E, GeV K. Griessinger (U Mainz) ISR physics at BABAR September / 23

12 Introduction The BABAR Experiment Experimental specifications Energy: s 1.58 GeV (E e 9. GeV, E e GeV), Luminosity: L 5 fb 1 (mostly Υ (4S)) K. Griessinger (U Mainz) ISR physics at BABAR September / 23

13 Introduction The BABAR Experiment Experimental specifications Energy: s 1.58 GeV (E e 9. GeV, E e GeV), Luminosity: L 5 fb 1 (mostly Υ (4S)) K. Griessinger (U Mainz) ISR physics at BABAR September / 23

14 Introduction Initial State Radiation (ISR) events at BABAR e (9GeV) γ ISR s = E CM hadrons γ hadrons e + (3GeV) ISR selection Detected high energy photon: E γ > 3GeV defines E CM & provides strong background rejection Event topology: γ ISR backtoback to hadrons high acceptance Kinematic fit including γ ISR very good energy resolution (4 15MeV) Continuous measurement from threshold to 5GeV provides common, consistent systematic uncertainties K. Griessinger (U Mainz) ISR physics at BABAR September / 23

15 Cross section e + e π + π e + e π + π Phys. Rev. D86 (212) 3213 [13] K. Griessinger (U Mainz) ISR physics at BABAR September / 23

16 Cross section e + e π + π Resulting cross section e + e π + π Cross section (nb) dominant background µ + µ (γ) CS calculated relative to µ + µ γ half of BABAR dataset used, new analysis in progress E CM (GeV) s (GeV) E CM (GeV) Syst. unc %.6.9.5% % % Contribution to g µ 2 a µ ( s < 1.8 GeV) = (514.9±2.22 stat ±3.11 syst ) 1 1 K. Griessinger (U Mainz) ISR physics at BABAR September / 23

17 Cross section e + e π + π Pion form factor π 2 F Fitted with GounarisSakurai parameterization [9] motivated by VMD allows comparison to other data E CM (GeV) s (GeV) K. Griessinger (U Mainz) ISR physics at BABAR September / 23

18 Cross section e + e π + π Pion form factor 2 π F Fitted with GounarisSakurai parameterization [9] motivated by VMD allows comparison to other data E CM (GeV) s (GeV) 4 F 2 π E CM s (GeV) (GeV) K. Griessinger (U Mainz) ISR physics at BABAR September / 23

19 Cross section e + e π + π Pion form factor 2 π F Fitted with GounarisSakurai parameterization [9] motivated by VMD allows comparison to other data F E CM (GeV) s (GeV) E CM s (GeV) (GeV) E CM s (GeV) (GeV) K. Griessinger (U Mainz) ISR physics at BABAR September / 23 F 2 π 2 π

20 Cross section e + e π + π π e + e π + π π Phys. Rev. D7 (24) 724 [2] K. Griessinger (U Mainz) ISR physics at BABAR September / 23

21 Cross section e + e π + π π Resulting cross section e + e π + π π Cross section (nb) BABAR SND DM M 3π (GeV/c 2 ) dominant bkg π + π π π disagreement with DM2 around 1.6 GeV/c 2 energy range 1.5 < E CM < 3 GeV Systematic uncertainties: 5 1% Contribution to g µ 2 (comp. [6]) a µ ( s < 1.8 GeV) = (46.2 ±.4 stat ± 1.4 syst ) 1 1 K. Griessinger (U Mainz) ISR physics at BABAR September / 23

22 Cross section e + e π + π π Intermediate resonances: ω, φ π + π π events/(2.5 MeV/c 2 ) 15 1 e + e π + π π M 3π (GeV/c 2 ) K. Griessinger (U Mainz) ISR physics at BABAR September / 23

23 Cross section e + e π + π π Intermediate resonances: ω, φ, and J/ψ π + π π events/(2.5 MeV/c 2 ) 15 1 e + e π + π π events/(2.5 MeV/c 2 ) M 3π (GeV/c 2 ) M 3π (GeV/c 2 ) J/ψ branching fraction B(J/ψ 3π) = (2.18 ±.19) % K. Griessinger (U Mainz) ISR physics at BABAR September / 23

24 Cross section e + e π + π π + π e + e π + π π + π Phys. Rev. D85 (212) 1129 [12] K. Griessinger (U Mainz) ISR physics at BABAR September / 23

25 Cross section e + e π + π π + π Resulting cross section σ(e + e π + π π + π ) (nb) CMD CMD2 ND SND OLYA GG2 e + e π + π π + π M3N DM1 DM2 BaBar 25 this work dominant bkgs K + K π + π and K s K ± π full data set Photon detection and tracking systematics improved E CM (MeV) E CM (GeV) Syst. unc % % > 2.8 4% Contribution to g µ 2 a µ ( s < 1.8 GeV) = (13.64 ±.3 stat ±.36 syst ) 1 1 K. Griessinger (U Mainz) ISR physics at BABAR September / 23

26 Cross section e + e π + π π + π Internal structure in various E CM energy slices Entries / 25 MeV/c GeV/c 2 DATA MC (EPJ C18, 497 (21)) First column (4 entries/event): a 1(126) GeV/c GeV/c GeV/c a 1 (126) GeV/c M 3π (GeV/c 2 ) M 2π (GeV/c 2 ) M 2π (GeV/c 2 ) K. Griessinger (U Mainz) ISR physics at BABAR September / 23

27 Cross section e + e π + π π + π Internal structure in various E CM energy slices Entries / 25 MeV/c GeV/c 2 DATA MC GeV/c GeV/c (EPJ C18, 497 (21)) ρ First column (4 entries/event): a 1(126) Second column (4 entries/event): strong ρ contribution e.g. for M 4π > 1.4 GeV/c 2 : 1/4th of entries in ρ peak ρ ρ is forbidden ρ in each event! GeV/c a 1 (126) GeV/c M 3π (GeV/c 2 ) M 2π (GeV/c 2 ) M 2π (GeV/c 2 ) K. Griessinger (U Mainz) ISR physics at BABAR September / 23

28 Cross section e + e π + π π + π Internal structure in various E CM energy slices Entries / 25 MeV/c a 1 (126) GeV/c GeV/c 2 DATA MC GeV/c GeV/c GeV/c 2 (EPJ C18, 497 (21)) ρ f 2 (127) f (98) First column (4 entries/event): a 1(126) Second column (4 entries/event): strong ρ contribution e.g. for M 4π > 1.4 GeV/c 2 : 1/4th of entries in ρ peak ρ ρ is forbidden ρ in each event! Third column (1 entry/event): 2π lie within ρ mass other π + π s mass plotted M 3π (GeV/c 2 ) M 2π (GeV/c 2 ) M 2π (GeV/c 2 ) M2π other Mρ < 25 MeV/c2 f 2(127), a 1(126), f (98)...? Partial Wave Analysis needed K. Griessinger (U Mainz) ISR physics at BABAR September / 23

29 Cross section e + e π + π π π e + e π + π π π PRELIMINARY submitted to PRD, arxiv: K. Griessinger (U Mainz) ISR physics at BABAR September / 23

30 Cross section e + e π + π π π Resulting cross section σ(e + e π + π 2π ) (nb) e + e π + π π π SND ADONE γγ2 ADONE MEA ACO DCIM3N ND OLYA BaBar PRELIMINARY dominant ISRbkg π + π 3π removed using data most precise measurement to date widest energy range.85 < E CM < 4.5 GeV E CM (GeV) E CM (GeV) Syst. unc % % > % Contribution to g µ 2 a µ (.85 < s < 1.8 GeV) = (17.9 ±.1 stat ±.6 syst ) 1 1 K. Griessinger (U Mainz) ISR physics at BABAR September / 23

31 Cross section e + e π + π π π Resulting cross section σ(e + e π + π 2π ) (nb) e + e π + π π π SND ADONE γγ2 ADONE MEA ACO DCIM3N ND OLYA BaBar PRELIMINARY σ () (nb) Data raw > σ tot /dm PRELIMINARY E CM (GeV) E CM (GeV) Syst. unc % % > % M 4π (GeV/c 2 ) Comparison to Chiral Pert. Theo. (Eur.Phys.J., C24: , 22 [7]) K. Griessinger (U Mainz) ISR physics at BABAR September / 23

32 Cross section e + e π + π π π Intermediate resonances J/ψ π + π π π σ (nb) e + e JPsi π + π π π PRELIMINARY M 4π (GeV/c 2 ) J/ψ branching fraction B(J/ψ 2π2π ) = (.51 ±.5) % K. Griessinger (U Mainz) ISR physics at BABAR September / 23

33 Cross section e + e π + π π π Intermediate resonances J/ψ, ωπ π + π π π σ (nb) e + e JPsi π + π π π M 4π (GeV/c 2 ) PRELIMINARY σ(e + e ωπ π + π 2π ) (nb) e + e ωπ π + π π π BaBar SND216 SND2 CMD2 DM2 PRELIMINARY E CM (GeV) J/ψ branching fraction B(J/ψ 2π2π ) = (.51 ±.5) % ωπ contribution to π + π 2π (32.1 ±.2 stat ± 2.6 syst ) % K. Griessinger (U Mainz) ISR physics at BABAR September / 23

34 Cross section e + e π + π π + π π e + e π + π π + π π Phys.Rev. D76 (27) 925 [3] K. Griessinger (U Mainz) ISR physics at BABAR September / 23

35 Cross section e + e π + π π + π π Resulting cross section σ(e + e 2(π + π )π ) (nb) E c.m. (GeV) E CM (GeV) Syst. unc % % > 3.5 5% e + e π + π π + π π dominant bkgs K + K π + π π and K s K ± π π most precise measurement to date energy range 1 < E CM < 4.5 GeV Contribution to g µ 2 (comp. [6]) a µ ( s < 1.8 GeV) = (.96 ±.9) 1 1 K. Griessinger (U Mainz) ISR physics at BABAR September / 23

36 Cross section e + e π + π π + π π Intermediate resonances: ω/ηπ + π e + e π + π π + π π σ(e + e 2(π + π )π ) (nb) 4 2 total ωπ + π ηπ + π E c.m. (GeV) K. Griessinger (U Mainz) ISR physics at BABAR September / 23

37 Cross section e + e π + π π + π π Intermediate resonances: ω/ηπ + π, J/ψ e + e π + π π + π π σ(e + e 2(π + π )π ) (nb) 4 2 total ωπ + π ηπ + π Events/.1 GeV/c E c.m. (GeV) m(2(π + π )π ) (GeV/c 2 ) J/ψ branching fraction B(J/ψ 4ππ ) = (5.46 ±.35) % K. Griessinger (U Mainz) ISR physics at BABAR September / 23

38 Cross section e + e π + π π + π π Intermediate resonances: ω/ηπ + π, J/ψ, and ψ(2s) e + e π + π π + π π σ(e + e 2(π + π )π ) (nb) 4 2 total ωπ + π ηπ + π Events/.1 GeV/c E c.m. (GeV) m(2(π + π )π ) (GeV/c 2 ) ψ(2s) branching fraction B(ψ(2S) 4ππ ) = (1.2 ± 1.1) % K. Griessinger (U Mainz) ISR physics at BABAR September / 23

39 Summary Summary ISR physics has proven to be a very productive field even years after the end of data taking at the Bfactories Precision measurements of hadronic cross sections have greatly improved aµ SM & more final states in preparation. Shown today: e + e π + π Phys. Rev. D86 (212) 3213 [13] e + e π + π π Phys. Rev. D7 (24) 724 [2] e + e π + π π + π Phys. Rev. D85 (212) 1129 [12] e + e π + π π π submitted to PRD, arxiv: e + e π + π π + π π Phys.Rev. D76 (27) 925 [3] New results from BABAR forthcoming: e + e π + π η e + e π + π (new method, full dataset) K. Griessinger (U Mainz) ISR physics at BABAR September / 23

40 Summary Thank you! Any questions? K. Griessinger (U Mainz) ISR physics at BABAR September / 23

41 References K. Griessinger (U Mainz) ISR physics at BABAR September / 23

42 References I [1] T. Aoyama, M. Hayakawa, T. Kinoshita, and M. Nio. Complete tenthorder qed contribution to the muon g 2. Phys. Rev. Lett., 19:11188, Sep 212. [2] B. Aubert et al. Study of e + e π + π π process using initial state radiation with BaBar. Phys.Rev., D7:724, 24. [3] B. Aubert et al. The e+ e 2(pi+ pi) pi, 2(pi+ pi) eta, K+ K pi+ pi pi and K+ K pi+ pi eta Cross Sections Measured with InitialState Radiation. Phys. Rev., D76:925, 27. [Erratum: Phys. Rev.D77,11992(28)]. K. Griessinger (U Mainz) ISR physics at BABAR September / 23

43 References II [4] G. Colangelo, M. Hoferichter, A. Nyffeler, M. Passera, and P. Stoffer. Remarks on higherorder hadronic corrections to the muon g 2. Phys.Lett., B735:9 91, 214. [5] M. Davier, A. Hoecker, B. Malaescu, and Z. Zhang. Reevaluation of the Hadronic Contributions to the Muon g 2 and to α(m Z ). Eur.Phys.J., C71:1515, 211. [6] M. Davier, A. Hoecker, B. Malaescu, and Z. Zhang. Reevaluation of the hadronic vacuum polarisation contributions to the Standard Model predictions of the muon g2 and alpha(mz) using newest hadronic crosssection data K. Griessinger (U Mainz) ISR physics at BABAR September / 23

44 References III [7] G. Ecker and R. Unterdorfer. FourPion Production in e + e Annihilation. Eur. Phys. J., C24: , 22. [8] C. Gnendiger, D. Stöckinger, and H. StöckingerKim. The electroweak contributions to (g 2) µ after the Higgs boson mass measurement. Phys.Rev., D88(5):535, 213. [9] G. J. Gounaris and J. J. Sakurai. Finite width corrections to the vector meson dominance prediction for ρ e + e. Phys. Rev. Lett., 21: , K. Griessinger (U Mainz) ISR physics at BABAR September / 23

45 References IV [1] F. Jegerlehner and A. Nyffeler. The Muon g2. Phys.Rept., 477:1 11, 29. [11] A. Kurz, T. Liu, P. Marquard, and M. Steinhauser. Hadronic contribution to the muon anomalous magnetic moment to nexttonexttoleading order. Phys.Lett., B734: , 214. [12] J. Lees et al. InitialState Radiation Measurement of the e + e π + π π + π Cross Section. Phys.Rev., D85:1129, 212. K. Griessinger (U Mainz) ISR physics at BABAR September / 23

46 References V [13] J. P. Lees et al. Precise Measurement of the e + e π + π (γ) Cross Section with the InitialState Radiation Method at BABAR. Phys. Rev., D86:3213, 212. [14] K. Olive et al. Review of Particle Physics. Chin.Phys., C38:91, 214. K. Griessinger (U Mainz) ISR physics at BABAR September / 23