Search results for "Pseudoscalar meson"
showing 10 items of 40 documents
Low-lying even parity meson resonances and spin-flavor symmetry
2010
A study is presented of the $s-$wave meson-meson interactions involving members of the $\rho-$nonet and of the $\pi-$octet. The starting point is an SU(6) spin-flavor extension of the SU(3) flavor Weinberg-Tomozawa Lagrangian. SU(6) symmetry breaking terms are then included to account for the physical meson masses and decay constants, while preserving partial conservation of the axial current in the light pseudoscalar sector. Next, the $T-$matrix amplitudes are obtained by solving the Bethe Salpeter equation in coupled-channel with the kernel built from the above interactions. The poles found on the first and second Riemann sheets of the amplitudes are identified with their possible Particl…
Decay of vector-vector resonances into $\gamma$ and a pseudoscalar meson
2010
We study the decay of dynamically generated resonances from the interaction of two vectors into a $\ensuremath{\gamma}$ and a pseudoscalar meson. The dynamics requires anomalous terms involving vertices with two vectors and a pseudoscalar, which renders it special. We compare our result with data on ${K}_{2}^{*+}(1430)\ensuremath{\rightarrow}{K}^{+}\ensuremath{\gamma}$ and ${K}_{2}^{*0}(1430)\ensuremath{\rightarrow}{K}^{0}\ensuremath{\gamma}$ and find a good agreement with the data for the ${K}_{2}^{*+}(1430)$ case and a width considerably smaller than the upper bound measured for the ${K}_{2}^{*0}(1430)$ meson. We also investigate the decay into ${\ensuremath{\pi}}^{+}\ensuremath{\gamma}$ …
Hidden gauge formalism for the radiative decays of axial-vector mesons
2009
24 pages, 6 tables, 11 figures.--ISI article identifier:000262979700040 .-- ArXiv pre-print avaible at:http://arxiv.org/abs/0809.0943
Antistrange meson-baryon interaction in hot and dense nuclear matter
2014
We present a study of in-medium cross sections and (off-shell) transition rates for the most relevant binary reactions for strange pseudoscalar meson production close to threshold in heavy-ion collisions at FAIR energies. Our results rely on a chiral unitary approach in coupled channels which incorporates the $s$- and $p$-waves of the kaon-nucleon interaction. The formalism, which is modified in the hot and dense medium to account for Pauli blocking effects, mean-field binding on baryons, and pion and kaon self-energies, has been improved to implement full unitarization and self-consistency for both the $s$- and $p$-wave interactions at finite temperature and density. This gives access to i…
Study of reactions disclosing hidden charm pentaquarks with or without strangeness
2016
We present results for five reactions, Lambda(b) -> J/psi K(-)p, Lambda(b) -> J/psi eta Lambda, Lambda(b) -> J/psi pi(-)p, Lambda(b) -> J/psi K-0 Lambda and Xi(-)(b) -> J/psi K-Lambda, where combining information from the meson baryon interaction, using the chiral unitary approach, and predictions made for molecular states of hidden charm, with or without strangeness, we can evaluate invariant mass distributions for the light meson baryon states, and for those of J/psi p or J/psi Lambda. We show that with the present available information, in all of these reactions one finds peaks where the pentaquark states show up. In the Lambda(b) -> J/psi K(-)p, and Lambda(b) -> J/psi pi(-)p reactions w…
The two-photon physics program at BESIII
2017
Abstract One of the main aspects of the two-photon physics program of the BESIII Collaboration is the determination of electromagnetic transition form factors (TFF). Precision measurements of TFF are needed as input to the calculations of the contribution of hadronic light-by-light scattering to the anomalous magnetic moment of the muon a μ . Data acquired with the BESIII detector allow for the determination of TFF of light pseudoscalar mesons at momentum transfers below 2 GeV2, the region of highest relevance for a μ . The measurements of the TFF of π 0 , η and η ′ mesons, as well as pion pairs, are presented, and the potential for a first double-tagged measurement of the pion transition f…
Radiative decay intoγPof the low lying axial-vector mesons
2008
We evaluate the radiative decay into a pseudoscalar meson and a photon of the whole set of the axial-vector mesons dynamically generated from the vector-pseudoscalar meson interaction. We take into account tree level and loop diagrams coming from the axial-vector decay into a vector and a pseudoscalar meson. We find a large span for the values of the radiative widths of the different axial-vector mesons. In particular, we evaluate the radiative decay into K{gamma} of the two K{sub 1}(1270) states, recently claimed theoretically, and discuss the experimental values quoted so far on the assumption of only one state.
B0andBs0decays intoJ/ψf0(980)andJ/ψf0(500)and the nature of the scalar resonances
2014
Abstract We describe the B 0 and B s 0 decays into J / ψ f 0 ( 500 ) and J / ψ f 0 ( 980 ) by taking into account the dominant process for the weak decay of B 0 and B s 0 into J / ψ and a q q ¯ component. After hadronization of this q q ¯ component into pairs of pseudoscalar mesons we obtain certain weights for the meson–meson components and allow them to interact among themselves. The final state interaction of the meson–meson components, described in terms of chiral unitary theory, gives rise to the f 0 ( 980 ) and f 0 ( 500 ) resonances and we can obtain the π + π − invariant mass distributions after the decay of the resonances, which allows us to compare directly to the experiments. We …
Chiral dynamics in theγp→π0ηpandγp→π0K0Σ+reactions
2006
Using a chiral unitary approach for meson-baryon scattering in the strangeness zero sector, where the ${N}^{*}(1535){S}_{11}$ resonance is dynamically generated, we study the reactions $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\eta}p$ and $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{K}^{0}{\ensuremath{\Sigma}}^{+}$ at photon energies at which the final states are produced close to threshold. Among several reaction mechanisms, we find the most important is the excitation of the ${\ensuremath{\Delta}}^{*}(1700){D}_{33}$ state, which subsequently decays into a pseudoscalar meson and a baryon belonging to the $\ensuremath{\Delta}(1232)…
Search for decays of the Z0 into a photon and a pseudoscalar meson
1990
Abstract A search is reported for decays of the Z 0 into π 0 γ , ηγ and η ′ (958) γ in e + e − collisions using data collected during a scan around the Z 0 mass. In order to search for π 0 γ final states, in which the two photons from the π 0 decay are unresolved, the production of pairs of high-energy electromagnetic clusters is studied. The data are compared with the expectations from the pure QED process e + e − → γγ , and a 95% confidence level upper limit on the branching ratio of the Z 0 into π 0 γ of 4.9 × 10 −4 is derived. For η′γ, the decay modes of the mesons that contain two charged particles are largely free from QED background. These modes are used to place upper limits of 4.6 …