0000000000284378
AUTHOR
Murat M. Kaskulov
On the background in the gamma p -> omega(pi(0)gamma)p reaction and mixed event simulation
In this paper we evaluate sources of background of the gamma p -> omega p reaction, with the omega detected through its pi(0)gamma decay channel, to compare with the experiment carried out at ELSA. We find background from gamma p -> pi(0)pi(0)p followed by decay of a pi(0) into two gamma, recombining one pi(0) and one gamma, and from the gamma p -> pi(0)eta p reaction with subsequent decay of the eta into two photons. This background accounts for the data at pi(0)gamma invariant masses beyond 700 MeV, but strength is missing at lower invariant masses which was attributed to photon misidentification events, which we simulate to get a good reproduction of the experimental background. Once thi…
$A$ dependence of the $\gamma$- and $p$-induced production of the $\Lambda(1520)$ from nuclei
Using results of a recent calculation of the $\Lambda(1520)$ in the nuclear medium, which show that the medium width is about five times the free width, we study the A dependence of the $\Lambda(1520)$ production cross section in the reactions $\gamma ~A \to K^+ \Lambda(1520) A^\prime$ and $p~ A \to p~ K^+ \Lambda(1520) A^\prime$. We find a sizable A dependence in the ratio of the nuclear cross sections for heavy nuclei with respect to a light one due to the large value of the $\Lambda(1520)$ width in the medium, showing that devoted experiments, easily within reach in present facilities, can provide good information on that magnitude by measuring the cross sections studied here.
Possible omega bound states in nuclei produced with the (gamma, p) reaction
We perform calculations for ω production in nuclei by means of the (γ,p) reaction for photon energies and proton angles suited to currently running and future experiments in present laboratories. For some cases of possible ω optical potentials, we find that clear peaks are observable when a good resolution in the ω energy is available. We also study the inclusive production of π(0)γ in nuclei around the ω energy and find a double hump structure for the energy spectra, with a peak around a π(0)γ energy of m(ω) -100 MeV, which could easily be misidentified by a signal of an ω bound state in nuclei, while it is actually due to a different scaling of the uncorrelated π(0)γ production and ω prod…
$\Lambda(1520)$ and $\Sigma(1385)$ in the nuclear medium
Recent studies of the $\Lambda(1520)$ resonance within chiral unitary theory with coupled channels find the resonance as a dynamically generated state from the interaction of the decuplet of baryons and the octet of mesons, essentially a quasibound state of $\pi \Sigma^*(1385)$ in this case, although the coupling of the $\Lambda(1520)$ to the $\bar{K}N$ and $\pi \Sigma$ makes this picture only approximate. The $\pi \Sigma^*(1385)$ decay channel of the $\Lambda(1520)$ is forbidden in free space for the nominal mass of the $\Sigma^*(1385)$, but the coupling of the $\pi$ to $ph$ components in the nuclear medium opens new decay channels of the $\Lambda(1520)$ in the nucleus and produces a much …
Inclusive omega photoproduction from nuclei and omega in the nuclear medium
With the aim of extracting information on the shift of the $\omega$ mass in the nuclear medium we analyze data obtained at ELSA from where claims for evidence of a mass shift of the $\omega$ have been made. We develop a Monte Carlo simulation code which takes into account the possible reactions in the experimental set up of $(\gamma ~ A \to \pi^0 \gamma ~X)$ in the vicinity of the $\omega$ production region with subsequent $\omega \to \pi^0 \gamma$ decay. We compare our results with experiment for the distribution of $\pi^0 \gamma$ invariant masses and conclude that the distribution is compatible with an enlarged $\omega$ width of about 90 MeV at nuclear matter density and no shift in the m…