KLOE results on  decays LNF Spring School “Bruno Touschek” Frascati, 16–20 May 2005 F. Perfetto (Università di Napoli “Federico II”  INFN) for the KLOE Collaboration Dynamics of →  decay BR of → 0

The → decay in PT The amplitude of the →  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: Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

 3 @ KLOE +-0 selection: 000 selection: At KLOE  is produced in the process  . N(2001-2002)  17 Mevts. The final state for  +-0 is thus +-, and the final state for  000 is 7, both with almost no physical background. 000 selection: 7 candidates Kinematic fit +-0 selection: 2 track vertex + 3 candidates Kinematic fit Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

The → +-0 Dalitz plot Dalitz shape X(T+-T-) , YT0 “core” Y = 0.027 “core” X = 0.018 Efficiency  36% , almost flat Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Fit to the → +-0 Dalitz plot |A(X,Y)|2 = 1+aY+bY2+cX+dX2+eXY+fY3 c and e are C violating KLOE Preliminary 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 1 63 -1.072  0.005 -0.008 +0.005 --- IN THIS TABLE WE SHOW THE RESULTS OF THE FIT TO THE DALITZ PLOT FOR DIFFERENT PARAMETRIZATION OF AMPLITUDE. WE ARE SENSITIVE TO CUBIC SLOPE IN Y, NEVER MESURED BEFORE. IN AGREEMENT TO C CONSERVATION THE C AND E PARAMETERS ARE CONSISTENT WITH ZERO. FIXING THIS PARAMETERS TO ZERO WE OBTAIN THE SAME RESULTS. Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Q evaluation Using this preliminary KLOE result: [B.V. Martemyanov and V.S. Sopov, PRD 71 (2005) 017501] Q = 22.8 ± 0.4 This result 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 (→ ) Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Asymmetries KLOE Preliminary 1 2 3 4 577741 577849 196104 196264 381585 381637 577741 577849 64082 304455 209204 209043 304930 63876 A = (-0.009  0.093)  10-2 Aq = (-0.02  0.09)  10-2 As = (0.07  0.09)  10-2 ASIMMETRY IS SENSITIVE TO I=0,1,2 C VIOLATING FINAL STATES Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Dalitz plot expansion  The Dalitz plot density for   000 ( |A|2 ) is specified by a single parameter: |A|2  1 + 2z with:  Z  [ 0 , 1 ] Ei = Energy of the i-th pion in the  rest frame.  = Distance to the center of Dalitz plot. max = Maximun value of . Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Matching  to 0 ‘s A 2 like variable is built for each of the 15 combinations in order to find the correct matching of photons to 0 ‘s Cutting on: Minimum 2 value 2 between “best” and “second” combination One can obtain samples with different purity-efficiency Purity = Fraction of events with all photons correctly matched to 0 ‘s Best purity obtained is 98.5% Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Results on MC Phase space Reconstructed Resolution Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Preliminary result  = 0.014  0.004stat  0.005syst We have analyzed 415 pb-1 of 2001-2002 data and we find the preliminary result, on the high purity sample: KLOE Preliminary  = 0.014  0.004stat  0.005syst  = 0.031 ± 0.004stat+syst Cfr. current best measurement (Crystal Ball): Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

→ 0: a window on p6 PT… 8 p2 L2 contributions at tree level: = 0 (Q = 0) 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 -loops = 0.84 ×10-3 eV K-loops = 2.45 ×10-3 eV THERE IS NO CONTRIBUTION AT THIS LEVEL. AT NEXT ORDER THE CONTRIBUTION FROM PION-LOOP AND K-LOOP ARE VERY SMALL. SO THE DOMINANT CONTRIBUTION COME FROM P6, AND THIS ARE THE RESULTS. L6 coefficients determined by the meson propagator. Th. expectations: 6VMD = ( 0.42 ± 0.20 ) eV 6ENJL = ( 0.58 ± 0.3 ) eV 6Ch unit = ( 0.47 ± 0.10 ) eV  0, ,  0  8 a0 0  p6 Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Analysis of → 0 @ KLOE }  →  0 5 final state  ~ 8 pb BR = (7.2  1.4)  104 GAMS2000 Background candidates: Process  (pb) e+e-→0, →0, 0→ 450 →f0, f0→00, 0→ 300 →a0, a0→0, /0→ 260 →, → 17000 →, →000 13000 Process  (pb) e+e-→0, →0, 0→ 450 →f0, f0→00, 0→ 300 →a0, a0→0, /0→ 260 →, → 17000 →, →000 13000 Process  (pb) e+e-→0, →0, 0→ 450 →f0, f0→00, 0→ 300 →a0 a0→0, /0→ 260 →, → 17000 →, →000 13000 Rejected with veto on additional -0- Rejected with energy momentum conservation and likelihood technique to identify splitted/merged clusters Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

BR(→ 0) = ( 8.4 ± 2.7stat ± 1.4syst ) × 10-5 → 0: BR evaluation Fit of data with superposition of background and signal shape. NDATA = 735 Nbkg = 667  36 Nsig = 68  23 N(30) = 2,288,882 THIS IS THE DISTRIBUTION OF INVARIANT MASS OF LESS ENERGETIC PHOTONS IN RED…. BR(→ 0) = ( 8.4 ± 2.7stat ± 1.4syst ) × 10-5 KLOE Preliminary Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

BR(→ 0: comparison with models GAMS (1984) Crystal Ball (2004) KLOE …. THE MEASURE IS SMALLER BY A FACTOR 3 WITH RESPECT TO CRYSTALL BALL KLOE 1 KLOE 2 KLOE 3 P6 calculations Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Conclusions We are analyzing an unprecedented statistics of 3 decays with negligible background and we have new and accurate values for the Dalitz plot slopes of both +-0 and 30 final states. We measure a value of BR(0) smaller by factor 3 w.r.t. recent Crystal Ball value (and an order of magnitude smaller than PDG value) still significantly different from zero, and in agreement with PT p6 calculations. KLOE as already published the best upper limit on C, P(C) violating decay (): BR()  1.3  10-5 [PLB 606 (2005) 276] BR()  1.6  10-5 [PLB 591 (2004) 49] Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Spare slides Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 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) Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Fit to the → +-0 Dalitz plot |A(X,Y)|2 = 1+aY+bY2+cX+dX2+eXY+fY3 c and e are C violating KLOE Preliminary 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 Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Dalitz expansion: theory vs experiment Calculation a b d Tree One-loop[1] Dispersive[2] Tree dispersive Absolute dispersive -1.00 0.25 0.00 -1.33 0.42 0.08 -1.16 0.26 0.10 -1.10 0.31 0.001 -1.21 0.33 0.04 [1] Gasser,J. and Leutwyler, H., Nucl. Phys. B 250, 539 (1985) [2] Kambor, J., Wiesendanger, C. and Wyler, D., Nucl. Phys. B 465, 215 (1996) Measurement N a b d Layter Gormley Crystal Barrel 80884 30000 1077 3230 -1.08  0.14 0.034  0.027 0.046  0.031 -1.17  0.02 0.21  0.03 0.06  0.04 -0.94 0.15 0.11  0.27 -1.22 0.07 0.22 0.11 0.06 fixed Tabella sperimentale di Bijnens Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Fit stability Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Dalitz expansion: theory vs experiment Calculation  Tree One-loop[1] Dispersive[2] Tree dispersive Absolute dispersive 0.00 0.0015 -0.007  -0.014 -0.006 -0.007 [1] Gasser,J. and Leutwyler, H., Nucl. Phys. B 250, 539 (1985) [2] Kambor, J., Wiesendanger, C. and Wyler, D., Nucl. Phys. B 465, 215 (1996) Alde (1984) -0.022  0.023 Crystal Barrel (1998) -0.052  0.020 Crystal Ball (2001) -0.031  0.004 Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005

Fit procedure The fit is done using a binned likelihood approach We obtain an extimate by minimizing Where: ni = recostructed events i = for each MC event (according pure phase space): Evaluate its ztrue and its zrec (if any!) Enter an histogram with the value of zrec Weight the entry with 1 + 2  ztrue Francesco Perfetto LNF Spring School "Bruno Touschek" May 20, 2005