Dynamics of the near threshold η meson production in proton-proton collisions N * (2007), Bonn, 07.09.2007 R. Czyżykiewicz for the COSY-11 collaboration:

Prezentacja na temat: "Dynamics of the near threshold η meson production in proton-proton collisions N * (2007), Bonn, 07.09.2007 R. Czyżykiewicz for the COSY-11 collaboration:"— Zapis prezentacji:

1 Dynamics of the near threshold η meson production in proton-proton collisions N * (2007), Bonn, 07.09.2007 R. Czyżykiewicz for the COSY-11 collaboration: IKP, Forschungszentrum Jülich, Germany INP, Jagiellonian University, Cracow, Poland IKP, Westfälische Wilhelms-Universität, Münster, Germany Institute of Nuclear Physics, Cracow, Poland Institute of Physics, University of Silesia, Katowice, Poland ZEL, Forschungszentrum Jülich, Jülich, Germany

2 Motivation: unknown production mechanism of the η meson Tools - measurements of: σ, dσ/dθ, A y, C ij

3 K. Nakayama et al., Phys. Rev. C65 (2002) 045210 Dane eksperymentalne: E. Chiavasa et al., Phys. Lett. B322 (1994) 270 H. Calen et al., Phys. Rev. Lett. 79 (1997) 2642 F. Hibou et al., Phys. Lett. B438 (1998) 41 J. Smyrski et al., Phys. Lett. B474 (2000) 180 B. Tatisheff et al., Phys. Rev. C62 (2000) 054001 H. Calen et al., Phys. Rev. C58 (1998) 2667 P. Moskal et al., Phys. Rev. C69 (2004) 025203 Experi,mental data: E. Chiavasa et al., Phys. Lett. B322 (1994) 270 H. Calen et al., Phys. Rev. Lett. 79 (1997) 2642 F. Hibou et al., Phys. Lett. B438 (1998) 41 J. Smyrski et al., Phys. Lett. B474 (2000) 180 B. Tatisheff et al., Phys. Rev. C62 (2000) 054001 H. Calen et al., Phys. Rev. C58 (1998) 2667 P. Moskal et al., Phys. Rev. C69 (2004) 025203 Total cross sections for the pp ppη reaction

4 Differential cross sections for the pp ppη reaction model: K. Nakayama et al., Phys. Rev. C65 (2002) 045210 data: M. Abdel-Bary et al., Eur. Phys. J. A16 (2003) 127

5 σ(pp ppη) = σ 1 σ(pn pnη) = ½ (σ 0 + σ 1 ) R η = σ(pn pnη) / σ(pp ppη) σ 0 = (2R η -1) σ 1 =12 σ 1 Isovector meson exchange H. Calén et al., Phys. Rev. C58 (1998) 2667 Isospin dependence of the η meson production

6 G. Fäldt, C. Wilkin – Phys. Scripta 64 (2001) 427 K. Nakayama et al., Phys. Rev. C68 (2003) 045201 Theoretical predictions for A y at Q=10 and 36 MeV G. Fäldt, C. Wilkin: A y ( ) = A y max sin(2 )

7 where: A y max = A y max (Q ) G. Fäldt, C. Wilkin: A y ( ) = A y max sin(2 )

8 Detection setup Beam: p(pol) COSY: ~7·10 9 x 10 6 /s Cluster target H 2 : ~10 13 atoms/cm 2 Momentum separation due to magnetic field Momentum reconstruction: DC+ magnetic field Velocity measurement – scintillator hodoscope Particle identification by means of the missing mass technique

9 σ(m η ) = 1.50 MeV/c 2 m 2 inv = [p 2 (1 - β 2 )] / β 2 m 2 X = ( E b + E t – E 1 – E 2 ) 2 - ( p b + p t – p 1 – p 2 ) 2

10 Madison convention ζ = {m pp, m p η, θ η, φ η, ψ} σ(ζ, P) = σ 0 (ζ) * (1 + PA y cos(φ η )) cos(φ η ) 1 N up + (θ η ) = σ 0 (θ η ) * (1 + P up A y (θ η ) ) * E(φ η, 0) * L up dt N dn - (θ η ) = σ 0 (θ η ) * (1 - P dn A y (θ η ) ) * E(φ η, 0) *L dn dt L rel = L up dt / L dn dt, P up P dn = P A y (θ η ) = 1 P N up + (θ η ) - L rel N dn - (θ η ) N up + (θ η ) + L rel N dn - (θ η )

11 Luminosity L rel L rel = L up dt / L dn dt = n up /n dn L rel (Q=10 MeV)= 0.98468 ± 0.00056(stat) ± 0.00985(sys) L rel (Q=36 MeV)= 0.98301 ± 0.00057(stat) ± 0.00983(sys)

12 Polarisation measurement

13 Polarisation

14 P(Q=10 MeV)= 0.680 ± 0.007(stat) ± 0.054(sys) -- COSY-11 P(Q=36 MeV)= 0.663 ± 0.003(stat) ± 0.008(sys) -- EDDA Polarisation

15 Asymmetries – Q = 36 MeV cos θ η N up + (cos θ η ) N dn - (cos θ η ) A y (cos θ η ) [-1 ; -0.5) --- --- --- [-0.5 ; 0) 103 ± 16(stat) ± 2(sys) 100 ± 18(stat) ± 2(sys) 0.039 ± 0.179(stat) ± 0.012(sys) [0 ; 0.5) 144 ± 16(stat) ± 2(sys) 153 ± 18(stat) ± 2(sys) -0.029 ± 0.122(stat) ± 0.010(sys) [0.5 ; 1] 259 ± 24(stat) ± 4(sys) 296 ± 28(stat) ± 4(sys) -0.084 ± 0.100(stat) ± 0.011(sys) R. Czyżykiewicz, P. Moskal et al., Phys. Rev. Lett. 98 (2007) 122003; R. Czyżykiewicz, P. Moskal et al., Int. J. Mod. Phys. 22 (2007) 518.

16 Asymmetries – Q = 10 MeV cos θ η N up + (cos θ η ) N dn - (cos θ η ) A y (cos θ η ) [-1 ; -0.5) 306 ± 27(stat) ± 5(sys) 250 ± 26(stat) ± 4(sys) 0.163 ± 0.099(stat) ± 0.022(sys) [-0.5 ; 0) 267 ± 22(stat) ± 4(sys) 260 ± 24(stat) ± 4(sys) 0.035 ± 0.091(stat) ± 0.012(sys) [0 ; 0.5) 198 ± 18(stat) ± 3(sys) 208 ± 19(stat) ± 3(sys) -0.021 ± 0.095(stat) ± 0.011(sys) [0.5 ; 1] 279 ± 23(stat) ± 4(sys) 286 ± 25(stat) ± 4(sys) -0.003 ± 0.088(stat) ± 0.009(sys ) R. Czyżykiewicz, P. Moskal et al., Phys. Rev. Lett. 98 (2007) 122003; R. Czyżykiewicz, P. Moskal et al., Int. J. Mod. Phys. 22 (2007) 518.

17 χ 2 pseudoscalar /DOF = 0.54 Prob(pseudoscalar) 81 % χ 2 vector /DOF = 2.76 Prob(vector) 0.6 % Results for Q = 10, and 36 MeV A y 0 s-wave production ( 2S+1 L J 2S'+1 L' J' s ) R. Czyżykiewicz, P. Moskal et al., Phys. Rev. Lett. 98 (2007) 122003; R. Czyżykiewicz, P. Moskal et al., Int. J. Mod. Phys. 22 (2007) 518.

18 where: A y max = A y max (Q ) G. Fäldt, C. Wilkin: A y ( ) = A y max sin(2 )

19 A y max (Q=10 MeV) = -0.071 ± 0.058 A y max (Q=36 MeV) = -0.081 ± 0.091 Results

20

21 A y max (Q=10 MeV) = -0.074 ± 0.062 A y max (Q=36 MeV) = -0.096 ± 0.108 Results

22 A y max (Q = 10 MeV) = -0.071 ± 0.058 A y max (Q = 36 MeV) = -0.081 ± 0.091 Results A y max (Q = 10 MeV) = -0.074 ± 0.062 A y max (Q = 36 MeV) = -0.096 ± 0.108 1 σ 4.3 σ R. Czyżykiewicz, P. Moskal et al., Phys. Rev. Lett. 98 (2007) 122003; R. Czyżykiewicz, P. Moskal et al., Int. J. Mod. Phys. 22 (2007) 518.

23 Predictions of the pseudoscalar meson dominance model are in line with the experimental data at the significance level of α = 0.81 indication of the π meson exchange Predictions of the vector meson exchange model, based on the η meson photoproduction aymmetries, disagree with the experimental data at a significance level of α = 0.006 Analysis of the A y max shown that the pseudoscalar meson exchange model agrees with the experimental data at the level of 1 σ, while the predictions of the vector meson exchange model lie within 4.3 σ from exp. data A y for Q = 10 and 36 MeV consistent with zero – possible production of the η meson in the s-wave Conclusions

24 Measurements with WASA-at-COSY

25 K. Nakayama, private communication (2007). S 11 (1535) D 13 (1520) + S 11 (1535) + S 11 (1650) + D 13 (1700)

26 Results

27

28 Kraków, 16.04.2007 Średnie geometryczne N ± : str. 11-12: N + = N + N + N - = N - N - N ( ) = s 0 (q ) * (1 + P A y (q ) ) * E(q, 0) * L dt N ( ) = s 0 (q ) * (1 + P A y (q ) ) * E(q, ) * L dt N ( ) = s 0 (q ) * (1 - P A y (q ) ) * E(q, ) * L dt N ( ) = s 0 (q ) * (1 - P A y (q ) ) * E(q, 0) * L dt

29 Produkcja rezonansowa Kraków, 16.04.2007

30 Wykresy Dalitz'a – Q=10 MeV PRELIMINARY Zgodne z wynikami dla Q=15.5 MeV P. Moskal et al., Phys. Rev. C69 (2004) 025203; K. Nakayama et al., Phys. Rev. C68 (2003) 045201) Kraków, 16.04.2007

31 Wykresy Dalitz'a c.d. PRELIMINARY Dopasowanie kinematyczne i poprawki na akceptancję Brakuje odcięcia tła Kraków, 16.04.2007

32 dane: P. Moskal et al., Phys. Rev. C69 (2004) 025203 M. Abdel-Bary et al., Eur. Phys. J. A16 (2003) 127 Róż niczkowe przekroje czynne dla pp pp Q = 15 i 15.5 MeV Q = 41 MeV Kraków, 16.04.2007

33 (pp pph) = 1 (pn pnh) = ½ ( 0 + 1 ) R h = (pn pnh) / (pp pph) 0 = (2R h – 1) 1 =12 1 (pp pph) = C|t p + t h + t r + t w | 2 |y I=1 (0)| 2 (pn pnh) = C|-3t p + t h + 3t r - t w | 2 |y I=0 (0)| 2 |y I=0 (0)| 2 / |y I=1 (0)| 2 = 0.8 |t p + t h + t r + t w | 2 |-3t p + t h + 3t r - t w | 2 =15 wymiana mezonów izowektorowych H. Calen et al., Phys. Rev. C58 (1998) 2667 C. Wilkin, Report No. TSL/ISV-96-0147 (1996) Kraków, 16.04.2007

34 Zasada zachowania parzystości a świetlność Kraków, 16.04.2007

35 2 pseudoscalar /DOF = 0.54 Prob(pseudoscalar) 81 % 2 vector /DOF = 2.76 Prob(vector) 0.6 % Wyniki analizy dla Q=10 oraz 36 MeV A y 0 prawdopod. fali s ( notacja: 2S+1 L J 2S'+1 L' J' s ) Kraków, 16.04.2007

36 A y max (Q=10 MeV) = -0.071 0.058 A y max (Q=36 MeV) = -0.081 0.091 Wyniki analizy Kraków, 16.04.2007

37 A y for the pp pp @ COSY-11 Q = 40 MeV P. Winter et al., Phys. Lett. B 544 (2002) 251; 553 (2003) 339 (E) G. Fäldt, C. Wilkin, Phys. Scripta 64 (2001) 427 K. Nakayama et al., Phys. Rev. C68 (2003) 045201 Kraków, 17.06.2007