1 / 24

KLOE results on hadron physics

MENU07, Julich 11/09/2007. KLOE results on hadron physics. Cesare Bini Università “La Sapienza” and INFN Roma. Outline: The KLOE experiment Results on pseudoscalar mesons Results on scalar mesons Prospects. 1. The KLOE experiment at DA  NE. DAFNE @ Frascati Laboratories

kcarol
Download Presentation

KLOE results on hadron physics

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. MENU07, Julich 11/09/2007 KLOE results on hadron physics Cesare Bini Università “La Sapienza” and INFN Roma Outline: The KLOE experiment Results on pseudoscalar mesons Results on scalar mesons Prospects

  2. 1. The KLOE experiment at DANE DAFNE @ Frascati Laboratories • e+e-collider with 2 separate rings: s = Mf= 1019.4 MeV • Luminosity up to 1.5×1032 cm-2s-1 • 2 interaction regions 1. KLOE 2700 pb-1 2. DEAR (kaonic atoms) 100 pb-1FINUDA (hypernuclei) 1100 pb-1 STATUS:  March 2006: end of KLOE data taking 2500 pb-1 on-peak 8 × 109f decays 200 pb-1 off-peak (energy scan + 1 GeV run)  December 2006 - June 2007: FINUDA run  Now: machine tests and preparation of SIDDHARTA (kaonic atoms) run

  3. The KLOE detector: A large drift chamber; A hermetic calorimeter A solenoidal superconducting coil Drift Chamber (He-IsoBut. 2m× 3m) E.M. Calorimeter (lead-scintillating fibres) Magnetic field (SuperConducting Coil) = 0.52 T (solenoid) The KLOE physics program: Kaon physics: CP and CPT violation, CKM unitarity, rare decays, ChPT tests Hadron physics: lowest mass pseudoscalar, scalar and vector mesons Hadronic cross-section below 1 GeV: hadronic corrections to g-2

  4. 2. Results on pseudoscalar mesons. The lowest mass pseudoscalar mesons (JPC=0-+) are accessible at a  - factory through the decays: B.R. Nev KLOE (2.5 fb-1) K+K-0.49 3.7  109 K0K0KSKL0.33 2.5  109 1.3  10-2 9.7  107 1.2  10-3 9.0  106 ’6.2  10-5 4.6  105 Results presented here: 2.1 Precision measurement of themass 2.2Improved measurement of the - ’ mixing 2.3 Dynamics of3decays 2.4 Measurement of KS 2.5 Other analyses in progress (, -e+e-)

  5. 2.1 Precision measurement of themass Motivated by the discrepancy between the two best measurements: NA48 (2002) M() = 547.843 ± 0.030 ± 0.041 MeV GEM (2005) M() = 547.311 ± 0.028 ± 0.032 MeV ( >10 , PDG average gives a scale factor of 5.8 !) Recently a new measurement has been presented by CLEO: CLEO (2007) M() = 547.785 ± 0.017 ± 0.057 MeV • KLOE method: analysis of fully neutral 3events • with  • with • 3 clusters in the calorimeter only. • Kinematic fit with 4 constraints ==> energies by cluster positions • Discrimination betweenandvery easy from Dalitz plot. • Absolute energy scale from the e+e- center of mass energys • (kinematic fit input) - calibrated comparing M() obtained by the • energy scan to the PDG value

  6. 3Dalitz plot mass peak KLOE final result: M() = 547.873± 0.007± 0.031 MeV Systematic error due to: - space uniformity; - Dalitz plot cuts. mass check: M() = 134.906 0.0120.048 (well compatible with PDG value)

  7. 2.2 Measurement of theh – h’mixing KLOE method: measurement of 2002 result (Phys.Lett.B541,45) Lint= 16 pb-1 ,  final states 2007 result (Phys.Lett.B648,267) Lint=427 pb-1 ,  final states Errors are now dominated by “intermediate  and ’ B.R.s”: (BR(’ ) known @ 3%, BR((’ ) @ 5.7%) (*) evaluated according to A.Bramon et al., Eur.Phys.J. C7, 271 (1999)

  8. KLOE analysis uses the constraints: J.L.Rosner, Phys.Rev. D27 (1983) 1101, A.Bramon et al., Phys.Lett. B503(2001) 271 E.Kou, Phys.Rev.D63(2001) 54027 Y1: ’ Y2: ’ Y3: R Y4: ’ A >3 effect is found: Z2’ = 0.14  0.04 P = (39.7  0.7)o R.Escribano and J.Nadal (JHEP 0705,006,2007) reanalyze all V P and P V decays updating wavefunction overlaps parameters ==> no evidence of gluonium content Experimentally: improve (’), BR(’), ’measurements Constrain to the ’ gluonium content:

  9.   Dalitz plot analysis: 1.34 106 events   ”slope” analysis: 0.65 106 events 2.3 Dynamics of the 3 decay '3 decay isospin violation in strong interactions mu md ms A test of low energy effective theories of QCD KLOE has studied with high statistics the dynamics of both channels:

  10. Fit results of the  Dalitzplot Including systematic errors a=-1.090  0.005 +0.008-0.019 b= 0.124  0.006  0.010 d= 0.057  0.006 +0.007-0.016 f= 0.14  0.01  0.02 Comments: 0. the odd terms (c and e) in X are compatible with 0 (no asymmetries); 1. the quadratic term in X (d) is unambiguosly different from 0; 2. the cubic term in Y (f) is needed to get an acceptable fit; 3. the b=a2/2(current algebra rule) is largely violated. According to B.Borasoy and R.Nissler (Eur.Phys.J.A26 (2005) 383) it is difficult to accomodate such a small b value in a ChPT approach

  11. Dalitz plot asymmetries ==> test of C invariance Left-Right C-invariance Quadrant C-invariance in I=2 amplit. Sextant C-invariance in I=1 amplit. (see J.G.Layter et al.,Phys.Rev.Lett.29 (1972) 316) KLOE results:x 5 statistics respect to best previous experiment All asymmetries are compatible with 0 up to the 10-3 level

  12. Fit results of the  ”slope” The slope is evaluated by comparing the z distribution of the data with a Montecarlo simulation with =0 (pure phase space)  High sensitivity to the value of M() (Dalitz plot contour) MC with M()=547.3 MC with M()=547.822 New result:  = -0.027  0.004 +0.004-0.006 ==> in agreement with Crystal Ball (=-0.0310.004);

  13. KLOE method:  KSKL - KS tagging provided by KL interacting in the calorimeter: - Large background from KS  decay (105 times more frequent) BR(KS )=(2.27  0.13(stat)+0.03 -0.04(syst))10-6 Result compared to other experiments and theory Red= MC signal Blue= MC background Points=data 2.4 Measurement of the decay KS  BR estimated by ChPT @ order p4 (G.D’Ambrosio, D.Espriu, Phys.Lett.B175 (1986)27)

  14. 2.5 Others (2 flashes on other ongoing KLOE analyses)   0: ChPT “golden mode” 3 signal (only 1/5 of full statistics) signal confirmed in full data sample. Updated B.R. result soon with 15% statistical error  +-e+e-: signal observed: 1500 events expected with 2.5 fb-1 Few % sensitivity on plane asymmetry (CP violation, D.Gao, Mod.Phys.Lett.A17 (2002) 1583)

  15. 3. Results on scalar mesons. KLOE contribution to the understanding of the lowest mass scalars: f0(980), a0(980), (500) through radiative decays in pairs of pseudoscalars •  S (I=0)f0   (I=0) f0  (I=1) a0 K+K- (I=0,1) f0a0  K0K0  (I=0,1) f0a0 Mass (GeV/c2) f(1020) 1 a0(980) f0(980) Motivations: 1. f |ss>scalar quark composition 2. Search for evidence of (500) k(800) s(500) Results presented here: 3.1 Review of KLOE results on f0(980) 3.2 High statistics study of(preliminary) 3.3 Search for the decay K0K0 : 0 I=0 I=1/2 I=1

  16. 3.1Review of KLOE results on f0(980) KLOE has observed the decay  f0(980) in and 00 channels: : Phys.Lett.B634 (2006) 148; : Phys.Lett.B537 (2002) 21; Eur. Phys.J. C49 (2006) 433; FB asymmetry Dalitzplot f0(980) massspectrum Fit results: 1.The Kaon-Loop well describes the mass spectra; 2.The f0(980) is strongly coupled to the s quark: gf0KK > gf0p+p-, gf0is large 3.The scalar amplitude has a large low mass tail (m<600 MeV) that can be interpreted as due to the (500) (not clear results yet);

  17. 3.2 High statistics study of  : the a0(980). “Pure” final state, expected dominance of a0(980) intermediate state • Selection of: • 1.  events with : fully neutral 5 events; • 2.  events with : 2tracks and 5 events • Background subtraction: 18% in sample 1, 13% in sample 2 • Event counting: 18400 in sample 1, 3600 in sample 2 B.R.( )(1) = (6.92  0.10stat 0.20syst) 10-5 B.R.( )(2) = (7.19  0.17stat 0.24syst) 10-5 In good agreement, (part of the systematic errors are common). Error improvement: 9% (Phys.Lett.B536 (2002) 216)  3% (this result) • M() spectra • Combined fit of the two spectra with a0 production parametrizations • (convoluted with efficiencies and resolutions)

  18. KL fit: points =data red =fitting curve (model  efficiency and resolution) The fit parameters. Ratio BR()/BR()  BR(  ) contribution (KL) Kaon-Loop: (N.Achasov,A.V.Kiselev, Phys.Rev.D73(2006)054029)  Ma0, couplings ga0KK ga0, phase  (NS) Breit-Wigner + polynominal “background”: (G.Isidori et al., JHEP0605 (2006) 049)  Ma0, couplings ga0ga0KK ga0

  19. Comments: 1. Good consistency between sample 1 and 2: the result is experimentally “solid”; 2. KL fit is stable, NS requires to fix some parameters; Results: 2.1 ga0KK 2 GeV and ga0KK / ga0  0.8  “conflict” with qqqq hypothesys (not for f0(980)); 2.2 Large values of BR( ) and of ga0 sizeable coupling with the (as for f0(980))

  20. 3.3 Search for the decay  KSKS In K0K0 the K0K0 pair is: in a J=0 state  = [|KSKS>+|KLKL>]/2; in a I=0,1 isospin state a0 and f0 can contribute; Very small allowed phase space: 2MK < MKK < Msmall B.R. Predictions on B.R.: from 10-13(no scalar contribution) up to 10-7 • We have used the decay chain: •  KSKS  ()()  4 tracks+1 photon (Emax=24 MeV) • Overall efficiency = 20.6% • Very small bckg (ISR KSKL) Result : (Ldt= 1.4 fb-1) 1 event found; 0 expected background; BR( KSKS)<1.810-8 90% CL

  21. 4. Prospects. The DAFNE team is testing now a new scheme to increase luminosity KLOE phase-2could start (2009):  10 times more statistics  improved detector(inner tracker, improved calorimeter readout,  tagger, new small angle calorimeters)  “enriched” physics program Kaon, , ’ decays (high statistics)    (sigma), 0 2 width deeply bound kaonic states (AMADEUS proposal) The possibility to increase the center of mass energy up to 2.5 GeV is also considered (KLOE phase-3)  physics program extended to hadronic cross-section (g-2, em) baryon time-like form factors (DANTE proposal)  physics (,’,f0(980),a0(980) 2 widths) [see http://www.lnf.infn.it/lnfadmin/direzione/roadmap/roadmap.html F.Ambrosino et al., Eur.Phys.J. C50,729 (2007)]

  22. Conclusions: Hadron Physics is an important part of the KLOE program; Many results have been obtained; Others are to come: full data sample to be analysed more channels not yet analysed

  23. SPARES

More Related