PWA of J/pp0 and measurement of J/pp, pp' H.X. Yang (for BESII collaboration.) yanghx@ihep.ac.cn Workshop on the Physics of Excited Nucleon – NSTAR2009, Beijing, April 19 – 22, 2009

Outline Introduction of BEPC and BESII Motivation PWA of Measurement of Summary

Beijing Electron Positron Collider (BEPC) at IHEP L ~ 51030 /cm2s at J/ Ebeam~ 1 – 2.5 GeV BESI: run from 1989-1998 BESII: run from 1999-2004 BESIII: running

BESII @ BEPC VC: xy = 100 m TOF: T = 180 ps  counter: r= 3 cm MDC: xy = 220 m BSC: E/E= 22 % z = 5.5 cm dE/dx= 8.5 %  = 7.9 mr B field: 0.4 T p/p =1.7%(1+p2) z = 3.1 cm 4

Motivation Probe the internal structure of baryons Search for missing baryons predicted by quark model Obtain a better understanding of the strong interaction force in the non-perturbative regine

First observation of N(2065) With J/pn- N*(1520) N*(1535) N*(1440)? N*(1650) N*(1675) N*(1680) Quark model predicts N(2050). Never observed. ? N(2050): 1/2+ or 3/2+ N(1440): （N(1440) peak: never be found before) Phys. Rev. Lett. 97 （2006）062001

Study of (i) 0  M2(p0) M

study of (ii)

PWA of (iii) Resonances used in PWA

Example of mass and width scan PWA of (iv) Example of mass and width scan After we decide the best fit result and check there isn’t other N* state needed, we optimize the masses and widths of some N* states. This is an example of mass and width optimization during our analysis. The left plot is mass optimized result and right is width optimized results of N(1520)

Comparison of data With fit results (I) PWA of (v) Comparison of data With fit results (I) + : data hist.: fit

Comparison of data With fit results (II) PWA of (vi) Comparison of data With fit results (II)

PWA of (vii) Nx(2065) exists in this channel with high significance (>>5σ) The spin-parity favors 3/2+ N* M(MeV/c2) (MeV/c2) JP fraction(%) Br (×10-4) N(1440) 1/2+ 9.74~25.93 1.33~3.54 N(1520) 3/2- 2.38~10.92 0.34~1.54 N(1535) 1/2- 6.83~15.58 0.92~2.10 N(1650) 1/2- 6.89~27.94 0.91~3.71 N(1710) 1/2+ 4.17~30.10 0.54~3.86 N(2065) 3/2+ 23.0~41.8 0.91~3.11

Measurement of the branching ratio PWA of (viii) Measurement of the branching ratio Estimate the detection efficiency of each resonance and normalize them with the corresponding fraction in PWA result. The total efficiency of is 13.8% We measure the branching ratio after the partial wave analysis because we use the detection efficiency include N*s. After the systematic errors analysis we get the branching ratio of J/psi to ppbar pi0 is ….

Study of (i) +-0  ’+- ’

Study of (ii) Invariant mass spectrums in

Study of (iii) Invariant mass spectrums in

Study of (iv) Measured Branching Ratios Decay Modes Nobs Br (10-4) PDG BESII J/p pbar  () J/p pbar  (+-0) 12220.1148.9 953.744.7 20.9  1.8 19.20.21.8 18.30.92.4 J/p pbar ’ (’+-) J/p pbar ’ (’) 64.511.5 200.329.3 94 2.30.40.4 1.90.30.3

summary The new excited baryon Nx(2065) is confirmed in with JP=3/2+ and Clear signals for N* are observed, the masses, widths and branching ratios are measured with PWA on N* signals are also observed in The branching ratios of and are measured

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