Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userModification of the $omega$-Meson Lifetime in Nuclear Matter
529
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The photo production of $omega$ mesons on the nuclei C, Ca, Nb and Pb has been measured using the Crystal Barrel/TAPS detector at the ELSA tagged photon facility in Bonn. The dependence of the $omega$ meson cross section on the nuclear mass number has been compared with three different types of models, a Glauber analysis, a BUU analysis of the Giessen theory group and a calculation by the Valencia theory group. In all three cases, the inelastic $omega$ width is found to be $130-150 rm{MeV/c^2}$ at normal nuclear matter density for an average 3-momentum of 1.1 GeV/c. In the restframe of the $omega$ meson, this inelastic $omega$ width corresponds to a reduction of the $omega$ lifetime by a factor $approx 30$. For the first time, the momentum dependent $omega$N cross section has been extracted from the experiment and is in the range of 70 mb.
rate research
Read More
We have measured invariant mass spectra of electron-positron pairs in the target rapidity region of 12GeV p+A reactions. We have observed a significant difference in the mass spectra below the $omega$ meson between p+C and p+Cu interactions. The difference is interpreted as a signature of the $rho/omega$ modification at normal nuclear-matter density.
We discuss the effect of changes in meson properties in a nuclear medium on physical observables, notably, $J/Psi$ dissociation on pion and $rho$ meson comovers in relativistic heavy ion collisions, and the prediction of the $omega$-, $eta$- and $eta$-nuclear bound states.
Invariant mass spectra of e+e- pairs have been measured in 12 GeV p+A reactions to detect possible in-medium modification of vector mesons. Copper and carbon targets are used to study the nuclear-size dependence of e+e- invariant mass distributions. A significant excess on the low-mass side of the phi meson peak is observed in the low beta gamma (=beta/sqrt(1-beta^2)) region of phi mesons (beta gamma < 1.25) with copper targets. However, in the high beta gamma region (beta gamma > 1.25), spectral shapes of phi mesons are well described by the Breit-Wigner shape when experimental effects are considered. Thus, in addition to our earlier publication on rho / omega modification, this study has experimentally verified vector meson mass modification at normal nuclear density.
Changes in the meson-nucleon coupling constant and the vertex form factor in nuclear matter are studied in a modified Skyrme Lagrangian including the sigma-meson field that satisfies the scale invariance. Renormalization of the axial-vector coupling constant, and the nucleon mass are studied in a consistent model. The results are consistent with the empirical evidence. A calculation of pi N commutator, sigma-term, indicates that the medium changes its magnitude considerably.
Heavy-flavor quarks are dominantly produced in initial hard scattering processes and experience the whole evolution of the system in heavy-ion collisions at RHIC energies. Thus they are suggested to be an excellent probe to the medium properties through their interaction with the medium. In this proceedings, we report our first measurement of $D^0$ production via topological reconstruction using STARs recently installed Heavy Flavor Tracker (HFT). We also report our new measurement of Nuclear Modification Factor ($R_{AA}$) of $D^0$ mesons in central Au+Au collisions at $sqrt{s_{NN}}$ = 200 GeV as a function of transverse momentum ($p_{T}$). New results confirm the strong suppression at high $p_{T}$ with a much improved precision, and show that the $R_{AA}$ at high $p_{T}$ are comparable with light hadrons ($pi$) and with D meson measurements at the LHC. Furthermore, several theoretical calculations are compared to our data, and with charm diffusion coefficient 2${pi}TD_{S}$ $sim$ 2-12 can reproduce both the $D^0$ $R_{AA}$ and $v_2$ data in Au+Au collisions at RHIC.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
