N[sup ∗] production from pp and p̄p collisions

Abstract

With an effective Lagrangian approach, we give a full analysis on the NN → NNππ and pp → pnπ + reactions for proton beam energy from 1 to 1.5 GeV. The results are very consistent with the experiment data from CELSIUS, KEK, COSY, and so on. Based on these results, we consider theNN →NNππ andpp →pnπ + for proton beam energy up to 4 GeV. Compare to the pp collisions, there are many benefits to study N * resonances in these two reactions. And for the high proton beam energy up to 15 GeV, we consider some new resonances with hidden charm which are definitely beyond three constituent quarks model in thepp →ppJ/ψ andpp →ppη c , where there are very nice places to find these new N * cc . The predicted results aboutpp collisions can be looked for at the forthcoming PANDA/FAIR experiments.

Multiquark States

“…This model requires J P = 3/2 − and provides a natural explanation for its narrow width. A dynamically generated c D * state was predicted by Wu et al (171,172) with a mass around 4,412 MeV and a total width of = 47.3 MeV, in agreement with the measured width, with the largest contribution from J/ψ p decays. This model also predicts several narrow J/ψ states, which can be probed in b → J/ψ K − decays.…”

Disentangling the nature of resonances in coupled-channel models

“…On the experimental side, the scattering of stable particles and the hadronic decay of heavy quarkonium are usually used to extract empirical information of resonances. The typical examples are the πN, γN [1][2][3][4][5], eN and pN reactions [6][7][8][9][10][11][12][13] and the decay of the charmonium states, e.g. J/ψ, ψ and χ cJ [14][15][16].…”

“…The states with isospin one should be studied in other reactions, but they are usually convoluted with isospin zero components. In the pN reactions [6][7][8][9][10][11][12][13], the coupledchannel effects are complicated due to three or more particles in final states so the study is still in the initial stage. For the photo-induced reactions, though the non-resonant background is large due to the enhancement of Born terms resulting from the gauge invariance [2], the unprecedented development of coupled-channel models has reliably dissociated the resonances from the background and investigated the properties of many states by treating the amount of πN and γN data on an equal footing.…”