RENCONTRES DE MORIOND 2005 – QCD and Hadronic Interactions KLOE results on f0(980) , a0(980) scalars and h decays S. Giovannella (LNFINFN) for the KLOE Collaboration Study of the f0(980) , a0(980) mesons Dynamics of h→ppp decay BR of h→p0gg RENCONTRES DE MORIOND 2005 – QCD and Hadronic Interactions La Thuile, 12–19 March 2005

DAFNE: the Frascati f-factory e+e– collider @ s 1020 MeV  M peak  3 mb 2004 best: Lpeak = 1.2 × 1032 cm-1s-1 F(1020) g a0(980) f0(980) h(550) h'(960) r(770) KK p 0- 1- 0+ p0 BR = 83% BR = 15% BR = 1.3%  L(pb-1) Lint(01/02) = 450 pb-1 Lint (2004) = 700 pb-1 2005: data taking in progress 1.5 ×109 f in 2001/2002 2.3 ×109 f in 2004 S. Giovannella - MORIOND QCD - 12-19 March 2005

The KLOE experiment The KLOE design was driven by the measurement of direct CP violation through the double ratio: R = G(KL p+p) G(KS p0p0) / G(KS p+p) G(KLp0p0) DRIFT CHAMBER: Helium based gas mixture dpt / pt < 0.4% xy  150 m ; z  2 mm E.M. CALORIMETER: sE / E = 5.4% / (E(GeV)) st = 55 ps / (E(GeV))  40 ps 98% solid angle coverage PID capabilities Magnetic field: B = 0.52 T S. Giovannella - MORIOND QCD - 12-19 March 2005

Light scalar mesons at KLOE g+f0(980) (I=0) g+a0(980) (I=1) p+p- p0p0 h p0 gg p+p- p0 e+e- →  ─ f0(980) and a0(980) scalar mesons not easily interpreted as qq states Other interpretations suggested:  qqqq states [Jaffe 1977]  KK molecule [Weinstein, Isgur 1990] Both BR(f→Sg) and scalar mass spectra are sensitive to their nature [Achasov, Ivanchenko 1989] ─ ─ ─ S. Giovannella - MORIOND QCD - 12-19 March 2005

Light scalar mesons at KLOE Properties of light scalars can be investigated by fitting the Dalitz plot of the three body PPg final state or the MPP spectra to extract the relevant couplings. We use two models: 1) Kaon Loop [Achasov-Ivanchenko, NPB315 (1989) 465] 2) “No Structure” [Isidori-Maiani, private comunication] S V g gVS gSpp P e+ e- S gfKK gSKK gSPP P K+ K- S described as a standard BW (fixed S) + higher order corrections S. Giovannella - MORIOND QCD - 12-19 March 2005

Fit to the M(hp) spectra 2001+2002 data: → (BR = 39.43%) 1.2  104 events 395+10 pb-1 →π+π-π0 (BR = 22.6% ) 4180 events Kaon Loop No Structure → → → →p+p-p0 →p+p-p0 →p+p-p0 Mπ (MeV) √s (MeV) S. Giovannella - MORIOND QCD - 12-19 March 2005

The p0p0g final state 450 pb-1 from 2001 – 2002 data taking ~ 400k events Two main contributions to p0p0g final state @ Mf: f→Sg→p0p0g √s = 1019.6 MeV e+e-→wp0→p0p0g S. Giovannella - MORIOND QCD - 12-19 March 2005

Fit to the p0p0g Dalitz: kaon loop Fit to the Dalitz plot includes: 1. scalar term [f0(980)] 2. VDM contributions 3. All interference terms Statistical errors only r/r p1(2) p2(1) g w e+ e─  Data  Fit f/w/w p1(2) p2(1) g r e+ e─ VDM well under control Scalar term not well reproduced S. Giovannella - MORIOND QCD - 12-19 March 2005

Fit to the p0p0g Dalitz: kaon loop Kaon loop model including s(600) according to PRD 56 (1997) 4084 significantly improves the fit!  Data  Fit Statistical errors only S. Giovannella - MORIOND QCD - 12-19 March 2005

Fit to the p0p0g Dalitz:no structure Also in this case we fit the p0p0g Dalitz with the scalar term, the VDM contributions and their interferences f0 + s (KL) Scalar (NS) Statistical errors only  Data  Fit Similar fit quality w.r.t. KL including s(600) Low mass tail less evident S. Giovannella - MORIOND QCD - 12-19 March 2005

The p+p-g final state e+e-→ +- events with the photon at large angle (45<<135) Main contributions: ISR (radiative return to , ) FSR Search for the f0 signal as a deviation on M(+-) spectrum from the expected ISR + FSR shape 676,000 events selected (2001+2002) Events/1.2 MeV f0(980) region M(pp) (MeV) M(pp) (MeV) √s (MeV) Expected interference pattern of svis vs √s in the signal region Mpp[9001000 MeV] S. Giovannella - MORIOND QCD - 12-19 March 2005

Fit to p+p-g Fit of the full Mpp spectrum with: KL NS Full spectrum Signal region ISR+FSR S. Giovannella - MORIOND QCD - 12-19 March 2005

Scalar mesons: coupling to the f In the “no structure” approach the crucial parameter is the coupling of the scalars to the f (i.e. to the s quark) Meson gfMg (GeV-1) p0 0.12 h 0.66 h 0.70 a0 1.3 f0 1.8 – 2.3 Increasing strange quark content Large coupling values! S. Giovannella - MORIOND QCD - 12-19 March 2005

The h→ppp decay in cPT The amplitude of the h→ppp decay occurs primarily due to the d-u quark mass difference. From lowest order Chiral Pertubation Theory: with and, at L.O. , A good understanding of M(s,t,u) can lead to a very accurate determination of Q: S. Giovannella - MORIOND QCD - 12-19 March 2005

The h→ppp decay @ KLOE The h meson is produced via f→ hg (17 Mevts in 2001/2002) Final state for h → p+p-p0 : +- Final state for h → p0p0p0 : 7g’s In both decays the physical background is almost negligible f→ hg → p0p0p0g p+p-p0 selection: 2 track vertex + 3g candidates Kinematic fit p0p0p0 selection: 7 photon candidates S. Giovannella - MORIOND QCD - 12-19 March 2005

The h→p+p-p0 Dalitz plot Resolution: Dalitz shape “core” sY = 0.027 “core” sX = 0.018 X(T+-T-) , YT0 B/S  0.8% Efficiency  36% , almost flat S. Giovannella - MORIOND QCD - 12-19 March 2005

Fit to the h→p+p-p0 Dalitz plot |A(X,Y)|2 = 1+aY+bY2+cX+dX2+eXY+fY3 KLOE Preliminary c and e are C violating Ndf P2 (%) a b c d e f 147 60 -1.072  0.006 -0.007 + 0.005 0.117  0.006 -0.006 +0.004 0.0001  0.0029 -0.0021 +0.0003 0.047 0.006 -0.005 +0.004 -0.006 0.008 -0. + 0.013 0.13 0.01 -0.01 +0.02 150 63 -1.072  0.005 -0.008 +0.005 --- 0.02 -1.055  0.004 -0.007 +0.006 0.100 0.005 -0.002 +0.004 0.12 0.01 -0.02 +0.02 -1.013  0.003 -0.007 +0.004 0.120  0.005 -0.023 + 0. 0.043 0.006 -0.003 +0.004 S. Giovannella - MORIOND QCD - 12-19 March 2005

Q evaluation Using the preliminary KLOE result presented @ ICHEP04 : [B.V. Martemyanov and V.S. Sopov, PRD 71 (2005) 017501] : Q = 22.8 ± 0.4 This result implies a violation of the Dashen theorem (QDT=24.2) based on DMp(e.m.)=DMK(e.m.) and is in agreement with: Q = 22.0 ± 0.6 [J.Donoghue and A.Perez, PRD 55 (1997) 7075] [J.Bijnens and J.Prades, NPB 490 (1997) 239] Q = 22.4 ± 0.9 [J.Kambor., C.Wiesendanger and D.Whyler, NPB 465 (1996) 215] Q = 22.7 ± 0.8 [A.V.Anisovich and H.Leutwyler, PLB 375 (1997) 335] The theoretical error is currently dominated by PDG error on G(h→ppp) S. Giovannella - MORIOND QCD - 12-19 March 2005

The h→p0p0p0 Dalitz plot z  [ 0 , 1 ] The Dalitz plot density is described with a single parameter: |A|2  1 + 2 a z with: Ei : Energy of the i-th pion in the h rest frame r : Distance from the center of the Dalitz plot rmax : Maximum value of r z  [ 0 , 1 ] S. Giovannella - MORIOND QCD - 12-19 March 2005

Fit to the h→p0p0p0 Dalitz plot 350 pb-1 of 2001-2002 data, using an high purity sample on the photon pairing in p0 → Purity = 98.5% , e = 4.5% a = -0.013 ± 0.005stat  0.004syst KLOE Preliminary Current best measurement from Crystal Ball: a = -0.031 ± 0.004stat+syst S. Giovannella - MORIOND QCD - 12-19 March 2005

h→p0gg: a window on p6 cPT…  0 8 L2 contributions at tree level: = 0 (Q = 0) p2 Coupling proportional to the charges, zero also for L4 @ tree level.  +,K+ -,K- 0 8 1-loop contributions from L2 vertices, suppressed by G parity conservation and kaon mass suppression: p4 Gp-loops = 0.84 ×10-3 eV GK-loops = 2.45 ×10-3 eV h r0, w, f p0 g L6 coefficients determined by the meson propagator. Th. expectations: G6VMD = ( 0.42 ± 0.20 ) eV G6ENJL = ( 0.58 ± 0.3 ) eV G6Ch unit= ( 0.47 ± 0.10 ) eV h8 a0 p0 g p6 S. Giovannella - MORIOND QCD - 12-19 March 2005

… and an experimental challenge! p- + p ® h + n (CERN, Brookhaven, GAMS, Crystal Ball) p+ + d ® p + p + h (67) p+ + p ® p+ + p +h (67,69) K- + p ® L + h (70 AGS) p+ + n ® h + p (71) p- + n ® p- + n + h (80) f ®hg (SND 01) S. Giovannella - MORIOND QCD - 12-19 March 2005

Analysis of h→p0gg @ KLOE } f → h g p0gg 5g final state s ~ 8 pb (GAMS BR measurement) Background candidates: Process s (pb) e+e-→wp0 , w→p0g , p0→gg 450 f→f0g , f0→ p0p0 , p0→gg 300 f→a0g , a0→ hp0 , h/p0→gg 260 f→hg , h→gg 17000 f→hg , h→ p0 p0 p0 13000 Process s (pb) e+e-→wp0 , w→p0g , p0→gg 450 f→f0g , f0→ p0p0 , p0→gg 300 f→a0g , a0→ hp0 , h/p0→gg 260 f→hg , h→gg 17000 f→hg , h→ p0 p0 p0 13000 Process s (pb) e+e-→wp0 , w→p0g , p0→gg 450 f→f0g , f0→ p0p0 , p0→gg 300 f→a0g , a0→ hp0 , h/p0→gg 260 f→hg , h→gg 17000 f→hg , h→ p0 p0 p0 13000 Rejected with veto on additional w-p0-h Rejected with energy momentum conservation and likelihood technique to identify merged clusters S. Giovannella - MORIOND QCD - 12-19 March 2005

BR(h→p0gg) = ( 8.4 ± 2.7stat ± 1.4syst ) × 10-5 h→p0gg: BR evaluation The shape of signal + background after fit well reproduces the data NDATA = 735 Nbkg = 667  36 Nsig = 68  23 N(3p0) = 2,288,882 BR(h→p0gg) = ( 8.4 ± 2.7stat ± 1.4syst ) × 10-5 KLOE Preliminary S. Giovannella - MORIOND QCD - 12-19 March 2005

BRh→p0gg: comparison with models [1] [2] [3] [4] [5] [6] [7] [8] GAMS (1984) [1] J. N. Ng et al.(1992) [2] J.N. Ng et al (1993) [3-4] L. Ametller et al. (1992) [5] S. Bellucci et al. (1995) [6] E. Oset et al (2003) [7] J. Bijnens et al. (1996) [8] A. A. Belkov et al.(1996) 68% 90% 95% 99% Statistical significance Crystal Ball (2004) KLOE KLOE 1s KLOE 2s KLOE 3s P6 calculations S. Giovannella - MORIOND QCD - 12-19 March 2005

Conclusions/Outlook The f0(980), a0(980) scalar resonances are clearly observed in different final states, indicating large values for the couplings with f We are analyzing an unprecedented statistics of h→3p decays, determining accurate values of the Dalitz plot slopes for p+p- p0 /p0 p0 p0 final states We measure a value of BR(h→p0gg) smaller than previous measurement and in agreement with ChPT p6 calculations A factor 5 improvement in statistics expected at the end of current run: Complection/extensions of the on-going analysis (including out of peak data) Search for S→KK Measure of all main h BRs + rare/forbidden h decays (Nh ~ 90 Mevts ) Limit on gluonium content in h [BR(f→hg)/BR(f→hg)] S. Giovannella - MORIOND QCD - 12-19 March 2005