Search results for "Eta meson"

Photo- and Electroproduction of Eta Mesons on Nucleons and Nuclei

1995

Eta photo- and electroproduction off the nucleon is investigated in an approach that contains Born terms, vector meson and nucleon resonance contributions. In a comparison with the new Mainz data we find a large sensitivity on the elementary ηN N coupling. Our analysis results in a pseudoscalar ηN N coupling with a coupling constant of g ηN N 2 /4π=0.4. Furthermore, we also study coincidence cross sections for eta electroproduction and present calculations for structure functions and kinematical conditions that are most sensitive to the S 11(1535) and the D 13(1520) resonances. Finally, we show results on the inclusive eta photoproduction off complex nuclei with a very good agreement with r…

Search for the rare charmless hadronic decayB+→a0+π0

2008

We present a search for B decays to a charged scalar meson a0+ and a pi0 where the a0+ decays to an eta meson and a pi+. The analysis was performed on a data sample consisting of 383x10-6 BBbar pairs collected with the Babar detector at the PEP-II asymmetric-energy B Factory at SLAC. We find no significant signal and set an upper limit on the product branching fraction BF[(B+ -> a0+ pi0) x (a0+ -> eta pi+)] of 1.4x10-6 at the 90% confidence level.

Spin dependence of {\eta} meson production in proton-proton collisions close to threshold

2018

Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and the high degree of the polarized proton beam of COSY, the reaction pp{\to} pp{\eta} has been measured close to threshold to explore the analyzing power Ay. The angular distribution of Ay is determined with the precision improved by more than one order of magnitude with respect to previous results allowing a first accurate comparison with theoretical predictions. The determined analyzing power is consistent with zero for an excess energy of Q = 15 MeV signaling s wave production with no evidence for higher partial waves. At Q = 72 MeV the data reveals strong interference of P s and P p partial waves …

Production of π0 and η mesons in Cu+Au collisions at √sNN = 200 GeV

2018

Production of π0 and η mesons has been measured at midrapidity in Cu+Au collisions at √sNN = 200 GeV. Measurements were performed in π0 (η) → γ γ decay channel in the 1(2)-20 GeV/c transverse momentum range. A strong suppression is observed for π0 and η meson production at high transverse momentum in central Cu+Au collisions relative to the p + p results scaled by the number of nucleon-nucleon collisions. In central collisions the suppression is similar to Au + Au with comparable nuclear overlap. The η/π0 ratio measured as a function of transverse momentum is consistent with mT -scaling parametrization down to pT = 2 GeV/c, its asymptotic value is constant and consistent with Au + Au and p …

Neutral pion and η meson production at midrapidity in Pb-Pb collisions at √sNN = 2.76 TeV

2018

Neutral pion and η meson production in the transverse momentum range 1 < p T < 20 GeV / c have been measured at midrapidity by the ALICE experiment at the Large Hadron Collider (LHC) in central and semicentral Pb-Pb collisions at √ s NN = 2.76 TeV. These results were obtained using the photon conversion method as well as the Photon Spectrometer (PHOS) and Electromagnetic Calorimeter detectors. The results extend the upper p T reach of the previous ALICE π 0 measurements from 12 to 20 GeV / c and present the first measurement of η meson production in heavy-ion collisions at the LHC. The η / π 0 ratio is similar for the two centralities and reaches at high p T a plateau value of 0.457 ± 0 . 0…

Electro-excitation of nucleon resonances and meson production

2005

"Table 8" of "Neutral pion and $\eta$ meson production at mid-rapidity in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV"

2018

Nuclear modification factor R_AA of $\eta$ produced in 20-50% central Pb-Pb collisions at sqrt{s_NN} = 2.76 TeV at mid-rapidity, T_AA uncertainty of 3.3% and uncertainty of \sigma_{inel} of 3.9% included in systematic uncertainties.

"Table 7" of "Neutral pion and $\eta$ meson production at mid-rapidity in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV"

2018

Nuclear modification factor R_AA of $\eta$ produced in 0-10% central Pb-Pb collisions at sqrt{s_NN} = 2.76 TeV at mid-rapidity, T_AA uncertainty of 3.25% and uncertainty of \sigma_{inel} of 3.9% included in systematic uncertainties.

"Table 3" of "Neutral pion and $\eta$ meson production at mid-rapidity in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV"

2018

Invariant yields of the $\eta$ meson in the centrality class 0-10% in Pb-Pb collisions at sqrt{s_NN} = 2.76 TeV at mid-rapidity.

"Table 4" of "Neutral pion and $\eta$ meson production at mid-rapidity in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV"

2018

Invariant yields of the $\eta$ meson in the centrality class 20-50% in Pb-Pb collisions at sqrt{s_NN} = 2.76 TeV at mid-rapidity.