η, η' photoproduction and electroproduction off nucleons

Photo- and electroproduction of eta, eta-prime mesons on protons are investigated within a relativistic chiral unitary approach based on coupled channels. The s wave potentials for electroproduction and meson-baryon scattering are derived from a chiral effective Lagrangian which includes the eta-prime as an explicit degree of freedom and incorporates important features of the underlying QCD Lagrangian such as the axial U(1) anomaly. The effective potentials are iterated in a Bethe-Salpeter equation and cross sections for eta, eta-prime photo- and electroproduction from protons are obtained. The results for the eta-prime photoproduction cross section reproduce the appearance of an S_(11) resonance around 1.9 GeV observed at ELSA. The inclusion of electromagnetic form factors increases the predicted eta electroproduction cross sections, providing a qualitative explanation for the hard form factor of the photocoupling amplitude observed at CLAS.

[1]  B. Borasoy,et al.  The η′→ηππ decay in U(3) chiral perturbation theory☆ , 2002 .

[2]  T. Inoue,et al.  Chiral unitary approach to S -wave meson baryon scattering in the strangeness S = 0 sector , 2001, hep-ph/0110333.

[3]  R. Workman,et al.  The pion-nucleon Sigma term is definitely large: results from a G.W.U. analysis of pion nucleon scattering data , 2001, hep-ph/0111066.

[4]  E. Santopinto,et al.  The hypercentral constituent quark model , 2001, 1506.05952.

[5]  B. Borasoy,et al.  η- mixing in U(3) chiral perturbation theory , 2001, hep-ph/0107175.

[6]  B. Borasoy.  Threshold eta and eta' electroproduction off nucleons , 2001, hep-ph/0105033.

[7]  J. A. Oller,et al.  Chiral dynamics in the presence of bound states: kaon–nucleon interactions revisited , 2000, hep-ph/0011146.

[8]  R. W. Major,et al.  The ep -->e'p eta reaction at and above the S11(1535) baryon resonance. , 2000, Physical review letters.

[9]  S. Bass,et al.  Axial U(1) dynamics in eta and eta' photoproduction , 2000, hep-ph/0007293.

[10]  H. Leutwyler,et al.  Large $N_ c$ in chiral perturbation theory , 2000, hep-ph/0007101.

[11]  N. Kaiser,et al.  Chiral SU(3) dynamics with coupled channels: inclusion of p-wave multipoles , 1999, nucl-th/9912053.

[12]  J. Nieves,et al.  Bethe–Salpeter approach for unitarized chiral perturbation theory , 1999, hep-ph/9907469.

[13]  B. Borasoy.  The eta' in baryon chiral perturbation theory , 1999, hep-ph/0001102.

[14]  A. Budzanowski,et al.  Measurement of γp→K0Σ+ at photon energies up to 1.55 GeV , 1999 .

[15]  J. A. Oller,et al.  Meson-meson interactions in a nonperturbative chiral approach , 1999 .

[16]  B. Borasoy.  Baryon axial vector currents , 1998, hep-ph/9811411.

[17]  E. al.,et al.  Electroproduction of the Delta (1232) resonance at high momentum transfer , 1998, nucl-ex/9811001.

[18]  M. Tran.  Measurement of ?p?K+? and ?p?K+S0 at photon energies up to 2 GeV , 1998 .

[19]  J. Smyrski,et al.  Photoproduction of η′-mesons with the 4π-detector SAPHIR , 1998 .

[20]  T. Feldmann,et al.  Flavor symmetry breaking and mixing effects in the $\eta \gamma$ and $\eta'\gamma$ transition form factors , 1997, hep-ph/9711231.

[21]  G. Anton,et al.  Break-up and Coherent Photoproduction of {eta} Mesons on the Deuteron , 1997 .

[22]  J. A. Oller,et al.  Chiral symmetry amplitudes in the S-wave isoscalar and isovector channels and the σ, f0(980), a0(980) scalar mesons , 1997 .

[23]  N. Kaiser,et al.  SU(3) chiral dynamics with coupled channels eta and kaon photoproduction , 1996, hep-ph/9607459.

[24]  Zhen-ping Li.  The photoproduction off the nucleon in the quark model , 1996, nucl-th/9607043.

[25]  J. Latorre,et al.  CHIRAL EFFECTIVE LAGRANGIAN IN THE LARGE-NC LIMIT: THE NONET CASE , 1996, hep-ph/9610549.

[26]  U. Meißner,et al.  Chiral expansion of baryon masses and $\sigma$-terms , 1996, hep-ph/9607432.

[27]  H. Leutwyler.  Bounds on the light quark masses , 1996, hep-ph/9601234.

[28]  N. Kaiser,et al.  Chiral dynamics and the S11 (1535) nucleon resonance , 1995, nucl-th/9507036.

[29]  Mukhopadhyay,et al.  Photoproduction of the eta ' mesons as a new tool to probe baryon resonances. , 1995, Physical review. C, Nuclear physics.

[30]  N. Kaiser,et al.  Chiral dynamics and the low-energy kaon - nucleon interaction , 1995, nucl-th/9505043.

[31]  Macgregor,et al.  Near threshold photoproduction of eta mesons off the proton. , 1995, Physical review letters.

[32]  B. Schoch.  Recent results from ELSA , 1995 .

[33]  L. Tiator,et al.  The ηNN coupling in eta photoproduction , 1994, nucl-th/9404013.

[34]  R. G. Roberts,et al.  Consistent analysis of the spin content of the nucleon , 1993, hep-ph/9306289.

[35]  Draper,et al.  Decuplet baryon structure from lattice QCD. , 1992, Physical review. D, Particles and fields.

[36]  Mukhopadhyay,et al.  eta photoproduction from threshold through the S11(1535) resonance. , 1991, Physical review letters.

[37]  C. Bennhold,et al.  Coherent and incoherent η-photoproduction from nuclei☆ , 1991 .

[38]  M. E. Sainio,et al.  Sigma term update , 1991 .

[39]  Carlson,et al.  Distribution amplitudes and electroproduction of the delta and other low-lying resonances. , 1988, Physical review. D, Particles and fields.

[40]  S. Weinberg.  The U(1) Problem , 1975 .

[41]  S. Okubo.  Note on Unitary Symmetry in Strong Interactions , 1962 .

[42]  M. Gell-Mann.  Symmetries of baryons and mesons , 1962 .