Related papers: An Update on the Hypothetical X17 Particle
Coherent pi0 photo- and electroproduction on 4He and 12C nuclei is investigated in the framework of a distorted wave impulse approximation in momentum space. The elementary process is described by the recently developed unitary isobar…
Collisions of Xe+Sn at beam energies of $E/A$ = 8 to 29 $MeV$ and leading to fusion-like heavy residues are studied using the $4\pi$ INDRA multidetector. The fusion cross section was measured and shows a maximum at $E/A$ = 18-20 $MeV$. A…
Particle production at LHC energies involves the interplay of hard (perturbative) and soft (non-perturbative) QCD processes. Global observables, such as the charged-particle multiplicity, are related to the initial geometry and the energy…
We estimate the values of Yukawa couplings of a light pseudoscalar A with a mass of about 17 MeV, which would explain the $^8Be$ anomaly observed in the Atomki pair spectrometer experiment. The resulting couplings of A to up and down type…
We study the $e^+e^-\to\gamma\omega J/\psi$ process using $11.6 ~\rm fb^{-1}$ $e^+ e^-$ annihilation data taken at center-of-mass energies from $\sqrt{s}=4.008~\rm GeV$ to $4.600~\rm GeV$ with the BESIII detector at the BEPCII storage ring.…
Spectroscopy results for Belle and BaBar are reported. A particular focus is put on new results of the X(3872) state with its radiative decays to $J$/$\psi$$\gamma$ and $\psi'$$\gamma$, its decay into $J$/$\psi$3$\pi$ and the search for…
This paper investigates the transverse momentum broadening effect for electromagnetic production of dileptons in ultra-peripheral heavy ion collisions accompanied by nuclear dissociation. The electromagnetic dissociation probability of…
Measurements of the $^2$H($^{16}$C,$^{16}$C$^{*}$$\rightarrow^4$He+$^{12}$Be or $^6$He+$^{10}$Be)$^2$H inelastic excitation and cluster-decay reactions have been carried out at a beam energy of about 23.5 MeV/u. A specially designed…
Magnetars in quiescent states continue to emit hard X-rays with a power far exceeding the loss of rotational energy. It has recently been noted that this hard X-ray continuum may bear a direct signature of quantum electrodynamic (QED)…
We perform a full amplitude analysis of the process $e^+ e^- \rightarrow J/\psi D \bar{D}$, where $D$ refers to either $D^0$ or $D^+$. A new charmoniumlike state $X^*(3860)$ that decays to $D \bar{D}$ is observed with a significance of…
During 2002-2003 the number of IR-identified counterparts to the Anomalous X-ray Pulsars (AXPs) has grown to four (4U0142+614, 2E2259+584, 1E 1048-59 and 1RXS J170849-400910) out of the six assessed objects of this class, plus two…
This letter reports results from the partial wave analysis of the $\pi^{-}\pi^{-}\pi^{+}\eta$ final state in $\pi^{-}p$ collisions at 18GeV/c. Strong evidence is observed for production of two mesons with exotic quantum numbers of spin,…
In a recent Letter [1] an overall agreement with the experimental data for the excitation of the single and double giant dipole resonances in relativistic heavy ion collision in 136Xe and 208Pb nuclei has been reported. We point out that…
Using the quasiclassical Green's function in the Coulomb field, we analyze the probabilities of single and multiple $e^+e^-$-pair production at fixed impact parameter $b$ between colliding ultrarelativistic heavy nuclei. We perform…
We present a search for a neutral, long-lived particle $L$ that is produced in $e^+e^-$ collisions and decays at a significant distance from the $e^+e^-$ interaction point into various flavor combinations of two oppositely charged tracks.…
In 2021, the Belle collaboration reported the first observation of a new structure in the $\psi(2S) \gamma$ final state produced in the two-photon fusion process. In the hadronic molecule picture, this new structure can be associated with…
We review recent studies on exotic states at the Belle experiment. The results include: (1) The measurement of the cross sections of $\gamma \gamma \to \omega \phi$, $\phi\phi$, and $\omega \omega$ for masses that range from threshold to…
We show that recently reported radioactive decay data support an earlier observation of an unexpected signal associated with the GW170817 binary neutron star inspiral.
The possible occurence of highly deformed configurations is investigated in the $^{40}$Ca and $^{56}$Ni di-nuclear systems as formed in the $^{28}$Si + $^{12}$C and $^{28}$Si + $^{28}$Si reactions, respectively, by using the properties of…
We demonstrate that the dip observed near the total energy of 3872 MeV in the recent cross section data from the BESIII Collaboration for $e^+e^-\to J/\psi\pi^+\pi^- $ admits a natural explanation as a coupled-channel effect: it is a…