Related papers: K+N scattering data and exotic Z+ resonances
We study meson-baryon scattering with strangeness -1 in unitary chiral perturbation theory. Ten coupled channels are considered in our work, namely $\pi^0 \Lambda$, $\pi^0 \Sigma^0$, $\pi^- \Sigma^+$, $\pi^+ \Sigma^-$, $K^- p$, $\bar{K}^0…
The one-pion exchange interaction between the kaon and the vector antikaon is investigated by solving the Schr\"odinger equation in the S-wave approximation. In addition to the particle $f_1(1285)$, another bound state of $K \bar{K}^*$ is…
We investigate S-wave kaon-nucleon ($KN$) interactions with strangeness $S=+1$ in lattice QCD using the time-dependent HAL QCD method. Employing the $(2+1)$-flavor gauge configuration with $m_{\pi}\approx 137~\textrm{MeV}$ and $m_{K}\approx…
A strangeness +1 exotic baryon Theta^+ has recently been seen in a number of experiments. We demonstrate that in large N_c QCD the existence of such a state implies the existence of S = +1 partner states with various spins and isospins but…
The K$^{-}$ over K$^{+}$ multiplicity ratio is measured in deep-inelastic scattering, for the first time for kaons carrying a large fraction $z$ of the virtual-photon energy. The data were obtained by the COMPASS collaboration using a 160…
Coupled-channel $\pi K$ and $\eta K$ scattering amplitudes are determined by studying the finite-volume energy spectra obtained from dynamical lattice QCD calculations. Using a large basis of interpolating operators, including both those…
Quenched and unquenched quark models predict very different patterns for the spectrum of the low excited hyperon states. Evidence is accumulating for the existence of some new hyperon resonances, such as a $\Sigma^*$ of spin-parity…
Motivated by the $1/N_c$ expansion, we study a simple model in which the pi-K scattering amplitude is the sum of a current-algebra contact term and resonance pole exchanges. This phenomenological model is crossing symmetric and, when a…
We have continued our investigation of the charge-exchange reaction K^+ Xe --> K^0 p Xe' in the bubble chamber DIANA. In agreement with our previous results based on part of the present statistics, formation of a narrow p K^0 resonance with…
A classification of the $IJ^{PC}=00^{++}$ mesons is performed on the basis of the K-matrix analysis of meson spectra in the reactions: (i) GAMS data on $\pi p\to \pi^0\pi^0 n$, $\eta\eta n$, $\eta\eta' n$; (ii) Crystal Barrel data on $p\bar…
A combined analysis of the published data on the pp -> dK+K0bar reaction at excess energies of 47.4 MeV and 104.7 MeV is presented. Evidence is found for both the production of the a0+(980)scalar resonance and for a strong K0bar:d final…
A search for additional evidence for the rare kaon decay K^+ --> pi^+ nu nubar has been made with a new data set comparable in sensitivity to the previous exposure that produced a single event.
Experimental evidence for and against the existence of pentaquarks has accumulated rapidly in the last three years. If they exist, they would be dramatic examples of hadronic states beyond our well-tested and successful particle models. The…
Neutron spin-flip scattering observations of a resonance in the superconducting state is often taken as evidence of an unconventional superconducting state in which the gap changes sign $\Delta(k+Q)=-\Delta(k)$ for momentum transfers $Q$…
Experimental data as a stereo photographs from the 2m propane bubble chamber LHE, JINR have been analyzed for exotic multibaryon metastable and stable states searches. A number of peculiarities were found in the effective mass spectra of:…
We report on the SVD-2 experiment data analysis aimed to search for an exotic baryon state, the $\Theta^+$-baryon, in a $pK^0_s$ decay mode with IHEP U-70 accelerator proton beam at $70 GeV/c$. A resonant structure with…
We discuss properties of 1^{-+} exotic mesons within the framework of the QCD field-theoretic approach. We estimate the mass of the lowest-lying 1^{-+} exotic meson using renormalization-improved QCD sum rules, and find that the mass lies…
Within the framework of a low-energy effective field theory we consider the procedure of extraction of the S-wave kaon-nucleon scattering lengths a0 and a1 from a combined fit to the kaonic hydrogen and kaonic deuterium data. It is…
The hadronic reaction pp --> Sigma+ K0 p was measured exclusively at a beam momentum of 2.95 GeV/c using the TOF detector at the COSY storage ring. A narrow peak was observed in the invariant mass spectrum of the K0 p subsystem at 1530 +- 5…
The first observation of exotic states with a new quark content $c \bar{c} u \bar{s}$ decaying to the $J/\psi K^+$ final state is reported with high significance from an amplitude analysis of the $B^+ \to J/\psi \phi K^+$ decay. The…