Related papers: Sequential single pion production explaining the d…
Based on measurements the branching ratios for the decay of the recently discovered dibaryon resonance $d^*(2380)$ into two-pion production channels and into the $np$ channel are evaluated. Possibilities for a decay into the isoscalar…
A model for the d d -> alpha pi pi reaction, based on two parallel N N -> d pi reactions, is extended to incorporate a complete set of input amplitudes. While low-energy cross sections are underestimated, the rich structure observed in the…
The reaction pp->pppi0pi0 has been investigated at a beam energy of 1.4 GeV using the WASA-at-COSY facility. The total cross section is found to be (324 +- 21_systematic +- 58_normalization) mub. In order to to study the production…
The total cross sections were measured for coherent double neutral-pion photoproduction on the deuteron at incident energies below 0.9 GeV for the first time. No clear resonance-like behavior is observed in the excitation function for…
The two-pion production in nucleon-nucleon collisions has been studied by exclusive and kinematically complete experiments from threshold up to $T_p$ = 1.36 GeV at CELSIUS-WASA. At near-threshold energies the total and differential…
We study the process $D^0 \to \pi^+ \pi^- f_0(980),\ f_0 \to \pi^+ \pi^-$ by introducing the triangle mechanism, in which $f_0(980)$ is considered to be dynamically generated from the meson-meson interaction. For the total contribution of…
The energy spectrum for high energy $\gamma$-rays ($E_\gamma \geq 10$ MeV) from the process $pp \to \gamma \gamma X$ emitted at $90^0$ in the laboratory frame has been measured at an energy below the pion production threshold, namely, at…
The new data on the elastic $pp$ and single pion production reaction $pp\to pn \pi^{+}$ taken at the incident proton momentum 1683 MeV/c are presented. The data on the $pp\to pn \pi^{+}$ reaction are compared with predictions from the OPE…
We evaluate the contribution to the $X(3872)$ width from a triangle mechanism in which the $X$ decays into $D^{*0}\bar{D}^0 -cc$, then the $D^{*0} (\bar{D}^{*0})$ decays into $D^0 \pi^0$ ($\bar{D}^0 \pi^0$) and the $D^0 \bar{D}^0$ fuse to…
The possible role of the triangle mechanism in the $B^-$ decay into $D^{*0}\pi^-\pi^0\eta$ and $D^{*0}\pi^-\pi^+\pi^-$ is investigated. In this process, the triangle singularity appears from the decay of $B^-$ into $D^{*0}K^-K^{*0}$…
The exotic hadron $G(3900)$, initially observed in the process $e^+ e^- \to D\bar{D}$, has been further supported by analyses from the BESIII Collaboration, which classify it as a $P$-wave molecular state of $D^{+}D^{*-}/D^{-}D^{*+}$.…
The pion-production $\pi^+ A \to \pi^+\pi^{\pm} A'$ reactions were studied on nuclei $^{2}H$, $^{12}C$, $^{40}Ca$ and $^{208}Pb$ at a pion energy of $T_{\pi^{+}}$=283 MeV using the CHAOS spectrometer. The experimental results are reduced to…
We have investigated the cross section for the $\pi^-p\rightarrow K^0\pi\Sigma$ and $pp\rightarrow pK^+\pi\Sigma$ reactions paying attention to a mechanism that develops a triangle singularity. The triangle diagram is realized by the decay…
The ABC effect -- an intriguing low-mass enhancement in the $\pi\pi$ invariant mass spectrum -- is known from inclusive measurements of two-pion production in nuclear fusion reactions. First exclusive measurements carried out at…
In the energy range of present and future accelerator-based neutrino-oscillation experiments, single-pion production (SPP) is one of the main contributions to the neutrino-nucleus scattering cross section. For these neutrino energies,…
Using the high-quality beam of storage rings in combination with a pellet target and the hermetic WASA detector covering practically the full solid angle the two-pion production in nucleon-nucleon collisions has been systematically studied…
The results from the first kinematically complete measurement of the dd --> 4Hepipi reaction are reported. The aim was to investigate a long standing puzzle regarding the origin of the peculiar pipi-invariant mass distributions appearing in…
A measurement is presented of the exclusive and semi-exclusive production of charged pion pairs in proton-proton collisions, pp to p(p*) + $\pi^+\pi^-$ + p(p*) here the $\pi^+\pi^-$ pair is emitted at central rapidities, and the scattered…
$d^\ast(2380)$ was observed by WASA-at-COSY collaborations in the nuclear reaction recently. Its particularly narrow width may indicate the new QCD-allowed hadronic structure. To further confirm the existence of this peculiar particle in a…
We consider exclusive $pp \to pp \pi^{+} \pi^{-}$ and $pp \to pp \pi^{+} \pi^{-}\pi^{+} \pi^{-}$ reactions at high energies. The calculation is based on a tensor pomeron model and the amplitudes for the processes are formulated in an…