|
|
Oset, E., Bayar, M., Dote, A., Hyodo, T., Khemchandani, K. P., Liang, W. H., et al. (2016). Two-, Three-, Many-body Systems Involving Mesons. Multimeson Condensates. Acta Phys. Pol. B, 47(2), 357–365.
Abstract: In this paper, we review results from studies with unconventional many-hadron systems containing mesons: systems with two mesons and one baryon, three mesons, some novel systems with two baryons and one meson, and finally, systems with many vector mesons, up to six, with their spins aligned forming states of increasing spin. We show that in many cases, one has experimental counterparts for the states found, while in some other cases, they remain as predictions, which we suggest to be searched in BESIII, Belle, LHCb, FAIR and other facilities.
|
|
|
|
Oset, E., Martinez Torres, A., Khemchandani, K. P., Roca, L., & Yamagata-Sekihara, J. (2012). Two, three, many body systems involving mesons. Prog. Part. Nucl. Phys., 67(2), 455–460.
Abstract: In this talk we show recent developments on few body systems involving mesons. We report on an approach to Faddeev equations using chiral unitary dynamics, where an explicit cancellation of the two body off shell amplitude with three body forces stemming from the same chiral Lagrangians takes place. This removal of the unphysical off shell part of the amplitudes is most welcome and renders the approach unambiguous, showing that only on shell two body amplitudes need to be used. Within this approach, systems of two mesons and one baryon are studied, reproducing properties of the low lying 1/2(+) states. On the other hand we also report on multirho and K* multirho states which can be associated to known meson resonances of high spin.
|
|
|
|
Martinez Torres, A., Khemchandani, K. P., Jido, D., Kanada-En'yo, Y., & Oset, E. (2013). Three-body hadron systems with strangeness. Nucl. Phys. A, 914, 280–288.
Abstract: Recently, many efforts are being put in studying three-hadron systems made of mesons and baryons and interesting results are being found. In this talk, we summarize the main features of the formalism used to study such three hadron systems with strangeness S = -1, 0 within a framework built on the basis of unitary chiral theories and solution of the Faddeev equations. In particular, we present the results obtained for the pi(K) over barN, K (K) over barN and KK (K) over bar systems and their respective coupled channels. In the first case, we find four Sigma's and two A's with spin-parity J(P) = 1/2(+), in the 1500-1800 MeV region, as two meson-one baryon s-wave resonances. In the second case, a 1/2(+) N* around 1900 MeV is found. For the last one a kaon close to 1420 MeV is formed, which can be identified with K(1460).
|
|
|
|
Martinez Torres, A., Khemchandani, K. P., & Oset, E. (2023). Theoretical study of the gamma d -> pi(0)eta d reaction. Phys. Rev. C, 107(2), 025202–24pp.
Abstract: We have done a theoretical study of the gamma d -> pi(0)eta d reaction starting with a realistic model for the gamma N -> pi(0)eta N reaction that reproduces cross sections and polarization observables at low energies and involves the gamma N -> Delta(1700) -> eta Delta(1232) -> eta pi N-0 process. For the coherent reaction in the deuteron we considered the impulse approximation together with the rescattering of the pions and the eta on a different nucleon than the one where they are produced. We found this second mechanism very important since it helps share between two nucleons the otherwise large momentum transfer of the reaction. Other contributions to the gamma d -> pi(0)eta d reaction, involving the gamma N -> pi(+/-)pi N-0' process, followed by the rescattering of the pi(+/-) with another nucleon to give eta and a nucleon, have also been included. We find a natural explanation, tied to the dynamics of our model, for the shift of the eta-d mass distribution to lower invariant masses, and of the pi(0)-d mass distribution to larger invariant masses, compared to a phase space calculation. We also study theoretical uncertainties related to the large momenta of the deuteron wave function involved in the process as well as to the couplings present in the model. Striking differences are found with the experimental angular distribution and further theoretical investigations might be necessary.
|
|
|
|
Sekihara, T., Martinez Torres, A., Jido, D., & Oset, E. (2012). Theoretical study of incoherent phi photoproduction on a deuteron target. Eur. Phys. J. A, 48(1), 10–17pp.
Abstract: We study the photoproduction of phi mesons in deuteron, paying attention to the modification of the cross-section from bound protons to the free ones. For this purpose we take into account Fermi motion in single scattering and rescattering of phi to account for phi absorption on a second nucleon as well as the rescattering of the proton on the neutron. We find that the contribution of the double scattering for phi is much smaller than the typical cross-section of gamma p -> phi p in free space, which implies a very small screening of the phi production in deuteron. The contribution from the proton rescattering, on the other hand, is found to be not negligible compared to the cross-section of gamma p -> phi p in free space, and leads to a moderate reduction of the phi photoproduction cross-section on a deuteron at forward angles if the LEPS set-up is taken into account. The Fermi motion allows contribution of the single scattering in regions forbidden by phase-space in the free case. In particular, we find that for momentum transfer squared close to the maximum value, the Fermi motion changes drastically the shape of d sigma/dt, to the point that the ratio of this cross-section to the free one becomes very sensitive to the precise value of t chosen, or the size of the bin used in an experimental analysis. Hence, this particular region of t does not seem to be the most indicated to find effects of a possible phi absorption in the deuteron. This reaction is studied theoretically as a function of t and the results are contrasted with recent experiments at LEPS and Jefferson Lab. The effect of the experimental angular cuts at LEPS is also discussed, providing guidelines for future experimental analyses of the reaction.
|
|
