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Now showing items 145 - 160 of 187

  • Test of h(1)(1830) made of K*K* with the eta(c) ->phi K*K* decay

    Ren, Xiu-Lei   Geng, Li-Sheng   Oset, E.   Meng, Jie  

    We present a new reaction, complementary to from which an h (1) resonance with mass around 1830 MeV was reported from a BESIII experiment. The new reaction is , or . Using the information from the analysis of , we find that the invariant mass distribution for those two Iu decays exhibits a clear peak around 1830 MeV perfectly distinguishable from what one obtains with pure phase space. We suggest the implementation of these reactions to assert the existence of this elusive resonance which, by its nature as a vector-vector molecule with 0(-)(1(+-)) quantum numbers, only couples to the channel.
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  • An alternative interpretation of the Theta(1540) peak in the gamma d -> K(+)K(-)np

    Torres, A. Martinez   Oset, E.  

    We use a theoretical model to study the gamma d -> K(+)K(-)np reaction adapted to the particular features of the experiment performed by the LEPS collaboration in which a signal in the K(+)n invariant mass was found and associated to the Theta(1540) pentaquark peak. Our study shows that the prescription used at LEPS to reconstruct the K(+)n invariant mass creates an artificial broad structure in the Theta(1540) region and that the LEPS collaboration underestimated the background in that region, such that the signal observed for the Theta(1540) is compatible with a fluctuation of 2 sigma over the calculated background.
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  • Hidden charm dynamically generated resonances and the e(+)e(-) -> J/psi D(D)over-bar, J/psi D(D)over-bar * reactions

    Gamermann, D.   Oset, E.  

    We analyze two recent reactions of Belle, producing D (D) over bar and D (D) over bar* states that have an enhancement of the invariant D (D) over bar, D (D) over bar* mass distribution above threshold, from the point of view that they might be indicative of the existence of a hidden charm scalar and an axial vector meson state below D (D) over bar or D (D) over bar* thresholds, respectively. We conclude that the data is compatible with the existing prediction of a hidden charm scalar meson with mass around 3700MeV, though other possibilities cannot be discarded. The peak seen in the D (D) over bar* spectrum above threshold is, however, unlikely to be due to a threshold enhancement produced by the presence, below threshold, of the hidden charm axial vector meson X(3872).
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  • States of rho D*(D)over-bar* with J=3D3 within the fixed center approximation to the Faddeev equations

    Bayar, M.   Ren, Xiu-Lei   Oset, E.  

    We study the interaction of rho, D* and (D) over bar* with spins aligned using the fixed center approximation to the Faddeev equations. We select a cluster of D*(D) over bar*, which is found to be bound in I =3D 0 and can be associated to the X(3915), and let the rho meson orbit around the D* and (D) over bar*. In this case we find an I =3D 1 state with mass around 4340 MeV and narrow width of about 50MeV. We also investigate the case with a cluster of rho D* and let the (D) over bar * orbit around the system of the two states. The rho D* cluster is also found to bind and leads to the D-2*(2460) state. The addition of the extra (D) over bar* produces further binding and we find, with admitted uncertainties, a state of I =3D 0 around 4000MeV, and a less bound narrow state with I =3D 1 around 4200 MeV.
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  • On the hidden charm pentaquarks in Lambda(b) -> J/psi K- p decay

    Roca, L.   Oset, E.  

    In a previous work we presented a theoretical analysis of the Lambda(b) -> J/psi K- p reaction based on which a recent experiment by the LHCb collaboration at CERN claimed the existence of two hidden charm pentaquarks, P-c(4380)(+) and P-c(4450)(+). In that work we focused only on the Lambda(1405) and P-c(4450)(+) signals and discussed the possible explanation of this pentaquark state within the picture of a dynamical meson-baryon molecule made up mostly from (D) over bar*Sigma(c) and (D) over bar*Sigma(c)* components. In the present work we improve upon the previous one by considering the total K- p and J/psi p data including all the relevant resonances contributing to the spectra, and discuss the possible nature of both P-c(4380)(+) and P-c(4450)(+). We also discuss several important topics, like the effect of the contact term in the reaction, the viability of reproducing the data without the P-c(4380)(+) and the possible quantum number assignment to these pentaquarks.
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  • Meson resonances in the open and hidden charm sectors

    Gamermann, D.   Oset, E.   Strottman, D.   Vacas, M. J. Vicente  

    We briefly present our model for generating open and hidden charm resonances and present the most interesting results. (c) 2008 Elsevier B.V. All rights reserved.
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  • Radiative decay into gamma-baryon of dynamically generated resonances from the vector-baryon interaction

    Garzon, E. J.   Sun, Bao-Xi   Oset, E.  

    We study the radiative decay into. and a baryon of the SU(3) octet and decuplet of nine and ten resonances that are dynamically generated from the interaction of vector mesons with baryons of the octet and the decuplet respectively. We obtain quite different partial decay widths for the various resonances, and for different charge states of the same resonance, suggesting that the experimental investigation of these radiative decays should bring much information on the nature of these resonances. For the case of baryons of the octet we determine the helicity amplitudes and compare them with experimental data when available.
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  • eta ' N scattering at low energies

    Oset, E.   Ramos, A.  

    We calculate the eta' amplitude at low energies considering chiral Lagrangians and eta eta' mixing, the coupling of eta'N to the vector-baryon channels and one Lagrangian allowed for singlet meson-baryon interaction. We obtain cross sections for elastic eta' scattering and transition of eta'N to the open channels pi N, eta N, eta'N, K Lambda and K Sigma,
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  • Study of the D* rho system using QCD sum rules

    Martinez Torres, A.   Khemchandani, K. P.   Nielsen, M.   Navarra, F. S.   Oset, E.  

    In this proceeding we present a study of the D* rho system made by using the method of QCD sum rules. Considering isospin and spin projectors, we investigate the different configurations and obtain three D* mesons with isospin I = 1/2, spin S = 0, 1, 2 and with masses 2500 +/- 67 MeV, 2523 +/- 60 MeV, and 2439 +/- 119 MeV, respectively. The last state can be related to D*(2) (2460) (spin 2) listed by the Particle Data Group, while one of the first two might be associated with D*(2640), whose spin-parity is unknown. In the case of I = 3/2 we also find evidences of three states with spin 0, 1 and 2, respectively, with masses 2467 +/- 82 MeV, 2420 +/- 128 MeV, and 2550 +/- 56 MeV.
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  • Triangle singularity enhancing isospin violation in (B)over-bar(s)(0)-> J/psi pi(0)f(0)(980)

    Liang, Wei-Hong   Sakai, S.   Xie, Ju-Jun   Oset, E.  

    We perform calculations for the (B) over bar (0)(s)-> J/psi pi(0)f(0)(980) and (B) over bar (0)(s)-> J/psi pi(0)a(0)(980) reactions, showing that the first is isospin-suppressed while the second is isospin-allowed. The reaction proceeds via a triangle mechanism, with (B) over bar (0)(s)-> J/psi K*(K) over bar +c.c., followed by the decay K*-> K pi and a further fusion of K (K) over bar into the f(0)(980) or a(0)(980). We show that the mechanism develops a singularity around the pi(0)f(0)(980) or pi(0)a(0)(980) invariant mass of 1420 MeV, where the pi(0)f(0) and pi(0)a(0) decay modes are magnified and also the ratio of pi(0)f(0) to pi(0)a(0) production. Using experimental information for the (B) over bar (0)(s)-> J/psi K*(K) over bar +c.c. decay, we are able to obtain absolute values for the reactions studied which fall into the experimentally accessible range. The reactions proposed and the observables evaluated, when contrasted with actual experiments, should be very valuable to obtain information on the nature of the low lying scalar mesons.
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  • The B+ -> J/phi omega K+ reaction and D*(D)over-bar* molecular states

    Dai, L. R.   Wang, G. Y.   Chen, X.   Wang, E.   Oset, E.   Li, D. M.  

    We study the B+J/K+ reaction, and show that it is driven by the presence of two resonances, the X(3940) and X(3930), that are of molecular nature and couple most strongly to D*D*, but also to J/. Because of that, in the J/ mass distribution we find a peak related to the excitation of the resonances and a cusp with large strength at the D*D* threshold.
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  • Dynamically generated resonances from the vector octet-baryon decuplet interaction

    Sarkar, Sourav   Sun, Bao-Xi   Oset, E.   Vicente Vacas, M. J.  

    We study the interaction of the octet of vector mesons with the decuplet of baryons using Lagrangians of the hidden gauge theory for vector interactions. The unitary amplitudes in coupled channels develop poles that can be associated with some known baryonic resonances, while there are predictions for new ones at the energy frontier of the experimental research. The work offers guidelines on how to search for these resonances.
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  • Three-body hadron systems with strangeness

    Torres, A. Martinez   Khemchandani, K. P.   Jido, D.   Kanada-En'yo, Y.   Oset, E.  

    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). (C) 2013 Elsevier B.V. All rights reserved.
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  • The three-body structure of the X(2175) and the Y(4260) states

    Martinez Torres, A.   Khemchamdani, K. P.   Oset, E.  

    In this talk, I discuss our study of three-meson systems where we find dynamical generation of two resonances: the X(2175) and the Y(4260). Experimentally, the former one has been found in the mass spectrum of the phi f(0)(980) system and the latter one in that of the J/psi pi pi system. Our study of these systems, using the Faddeev equations, reveals that these resonances possess a three-body structure.
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  • Heavy meson production in hot dense matter

    Tolos, L.   Gamermann, D.   Garcia-Recio, C.   Molina, R.   Nieves, J.   Oset, E.   Ramos, A.  

    The properties of charmed mesons in dense matter are studied using a unitary coupled-channel approach in the nuclear medium which takes into account Pauli-blocking effects and meson self-energies in a self-consistent manner. We obtain the open-charm meson spectral functions in this dense nuclear environment, and discuss their implications on hidden charm and charm scalar resonances and on the formation of D-mesic nuclei at FAIR energies.
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  • Kaon absorption in flight and the binding of (K)over-bar in nuclei

    Oset, E.   Magas, V. K.   Ramos, A.   Yamagata-Sekihara, J.   Hirenzaki, S.  

    We make a theoretical study of the kaon absorption in flight on nuclei with a kaon beam of 1 GeV momentum, paying special attention to the forward and energetic emitted protons, which were used to claim a deep kaon nucleus optical potential in a recent experiment. We perform a Monte Carlo simulation of this reaction, which allows to account not only for quasi-elastic (K) over bar p scattering, but also for the other processes which contribute to the proton spectra and which are not taken into account by the ordinary Green's function method analysis. The experiment looks for fast protons, but in coincidence with at least one charged particle in a decay counters sandwiching the target. The coincidence requirement is assumed not to distort the shape of the proton spectra, but we show that this is not the case and as a consequence the conclusions drawn from the experimental analysis do not hold.
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