相关论文: On Narrow Nucleon Excitation N*(1685)

Photoproduction of $\eta$ mesons off $^{12}$C, $^{40}$Ca, $^{93}$Nb, and $^{nat}$Pb nuclei has been measured with a tagged photon beam with energies between 0.6 and 2.2 GeV. The experiment was performed at the Bonn ELSA accelerator with the…

We re-analyze the predictions of chiral-soliton models for the masses and decay widths of baryons in the exotic antidecuplet of flavour SU(3). The calculated ranges of the chiral-soliton moment of inertia and the \pi-nucleon scattering…

A narrow baryon resonance is observed in invariant mass of the pKshort system formed in neutrino and antineutrino collisions with nuclei. The mass of the resonance is estimated as (1533+-5)MeV. The observed width is less than 20 MeV, and is…

Quasi-free photoproduction of $\pi\eta$-pairs has been investigated from threshold up to incident photon energies of 1.4 GeV, respectively up to photon-nucleon invariant masses up to 1.9 GeV. Total cross sections, angular distributions,…

We examine eta prime photoproduction, as a novel tool to study baryon resonances around 2 GeV, of particular interest to the quark shell model, which predicts a number of them. We find important roles of the form factors at the strong…

Identifying a zero-range exchange of vector mesons as the driving force for the s-wave scattering of pseudo-scalar mesons off the baryon ground states, a rich spectrum of molecules is formed. We argue that chiral symmetry and large-$N_c$…

A search is presented for a narrow resonance decaying to a pair of oppositely charged muons using $\sqrt{s} =$ 13 TeV proton-proton collision data recorded at the LHC. In the 45-75 and 110-200 GeV resonance mass ranges, the search is based…

The known ratio of the branching fractions for D_s^* --> D_s pi^0 and D_s^* --> D_s gamma may be used to extract the coupling of eta mesons to strange quarks once the value of the pi^0-eta mixing angle is known. This requires that realistic…

CLAS photoproduction data on deuterium and hydrogen targets have been analyzed in a search for an exotic baryon state with strangeness S=+1, the \Theta^+ (originally named the Z^+). This resonance was predicted recently in theoretical work…

A formalism is developed for the partial wave analysis of data on meson photoproduction off deuterons and applied to photoproduction of $\eta$ and $\pi^0$ mesons. Different interpretations of a dip-bump structure of the $\eta$…

We present a unitary and gauge-invariant model with coupled channels, which provides a consistent description of pion photoproduction off nucleons in the E$_{0+}$ channel and eta-meson photoproduction off protons and deuterons. An effective…

We reexamine properties of the baryon antidecuplet $\Theta^+$ and $N^*$, and the $\pi N$ sigma term within the framework of a chiral soliton model, focusing on their dependence on the $\Theta^+$ mass. It turns out that the measured value of…

An overview of the GW SAID and ITEP groups effort to analyze pion photoproduction on the neutron-target will be given. The disentanglement the isoscalar and isovector EM couplings of N* and Delta* resonances does require compatible data on…

Advances in the exploration of the spectrum and structure of the excited states of the nucleon from experiments with electromagnetic probes on proton targets are presented. Impressive progress has been achieved in the studies of exclusive…

Quasi-free photoproduction of $\eta$-mesons has been measured off nucleons bound in $^3$He nuclei for incident photon energies from the threshold region up to 1.4 GeV. The experiment was performed at the tagged photon facility of the Mainz…

All the time since its discovery the N$^*$(1440) baryon state, commonly known as Roper resonance, has been a state with many question marks - despite of its 4-star ranking in the particle data book. One reason is that it does not produce…

Impressive progress achieved in the past decade in experimental studies of exclusive meson photoproduction off protons and global multi-channel amplitude analyses has resulted in the discovery of several long-awaited new nucleon resonances,…

We observe narrowband pairs of time-correlated photons of wavelengths 776\,nm and 795\,nm from non-degenerate four-wave mixing in a laser-cooled atomic ensemble of $^{87}${Rb} using a cascade decay scheme. Coupling the photon pairs into…

We calculate formation spectra of eta-nucleus systems in (pi,N) reactions with nuclear targets, which can be performed at existing and/or forthcoming facilities, including J-PARC, in order to investigate eta-nucleus interactions. Based on…

The existence of non-strange partner of pentaquark, the J^p = 1/2^+ narrow resonance, has been investigated by utilizing kaon photoproduction off a proton. It is found that the corresponding mass is 1650 MeV and the appropriate observables…