536 research outputs found
Carta manuscrita de Eulogio Oset (Port Jefferson, EUA) a Pere Pascual comentant diverses notícies
No full textCarta de Eulogio Oset a l'oficina editorial de Nuclear Physics (Copenhaguen) adjuntant còpia d'un treball que voldria veure publicat
No full textCarta manuscrita de Eulogio Oset (SUNY at Stony Brook, NY, EUA) a Pere Pascual comentant diverses notícies
No full text
Carta manuscrita d'Eulogio Oset Báguena (Universidad de Salamanca) a Pere Pascual comentant diverses notícies
No full textHeavy meson production in hot dense matter
No full textThe 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.</p
On the ambiguities of sign determination of the S-matrix from energy levels in a finite box
No full textIn a recent paper the authors make a study on the determination of the S-matrix elements for scattering of particles in the infinite volume from the energy levels in a finite box for the case of multiple channels. The study is done with a toy model in 1+1 dimension and the authors find that there is some ambiguity in the sign of nondiagonal matrix elements, casting doubts on whether the needed observables in the infinite volume can be obtained from the energy levels of the box. In this paper I present an easy derivation, confirming the ambiguity of the sign and argue that this, however, does not put restrictions in the determination of observables.The author would like to thank T. Cohen and A.
Parre ̃no for discussions and Michael D ̈oring for a careful
reading of the manuscript. This work is partly supported
by DGICYT contract FIS2011-28853-C02-01, FEDER
funds of the EU, the Generalitat Valenciana in the pro-
gram Prometeo, 2009/090, and the EU Integrated Infras-
tructure Initiative Hadron Physics 3 Project under Grant
Agreement no. 283286Peer reviewe
Transparency ratio in γ A -> η' A ' and the in-medium η ' width
No full textThe photoproduction of η′η′-mesons off different nuclei has been measured with the CBELSA/TAPS detector system for incident photon energies between 1500-2200 MeV. The transparency ratio has been deduced and compared to theoretical calculations describing the propagation of η′η′-mesons in nuclei. The comparison indicates a width of the η′η′-meson of the order of Γ=15-25 MeVΓ=15-25 MeV at ρ=ρ0ρ=ρ0 for an average momentum pη′=1050 MeV/cpη′=1050 MeV/c, at which the η′η′-meson is produced in the nuclear rest frame. The inelastic η′Nη′N cross section is estimated to be 3-10 mb. Parameterizing the photoproduction cross section of η′η′-mesons by σ(A)=σ0Aασ(A)=σ0Aα, a value of α=0.84±0.03α=0.84±0.03 has been deduced.M. Nanova1, V. Metag1, A. Ramos2, E. Oset3, I. Jaegle4,a, K. Makonyi1, K. Brinkmann5,
O. Bartholomy5, D. Bayadilov5,6, Y.A. Beloglazov6, V. Crede5,b, H. Dutz5, A. Ehmanns5,
D. Elsner7, K. Essig5, R. Ewald7, I. Fabry5, M. Fuchs5, Ch. Funke5, R. Gregor1,
A.B. Gridnev6, E. Gutz5, S. H¨offgen5, P. Hoffmeister5, I. Horn5, J. Junkersfeld5,
H. Kalinowsky5, Frank Klein7, Friedrich Klein7, E. Klempt5, M. Konrad7, B. Kopf8,9,
B. Krusche4, J. Langheinrich7,9, H. L¨ohner10, I.V. Lopatin6, J. Lotz5, S. Lugert1,
D. Menze7, T. Mertens4, J.G. Messchendorp10, C. Morales7, R. Novotny1, M. Ostrick7,c,
L.M. Pant1,d, H. van Pee5, M. Pfeiffer1, A. Roy1,e, A. Radkov6, S. Schadmand1,f ,
Ch. Schmidt5, H. Schmieden7, B. Schoch7, A. S¨ule7, V. V. Sumachev6,
T. Szczepanek5, U. Thoma5, D. Trnka1, R. Varma1,g, D. Walther5, Ch. Wendel5
(The CBELSA/TAPS Collaboration)Ramos, A., Oset, E.,... [et al.] fins 61 autor
Dynamical Hadrons: Case Studies of Meson-Meson and Meson-Baryon Molecules and Triangle Singularities
No full textIn this thesis we use various methods to study the interaction of hadrons. We focus on topics related to exotic hadrons, such as tetraquarks from meson-meson interaction, pentaquarks from meson-baryon, and also triangular singularities. We show how experimental data can be explained with our theoretical models, and make predictions that can be compared with future experiments.
In chapter 1 we show our method to describe meson-meson interactions, known as chiral unitary approach, showing how the interaction of pseudoscalars generates the f0(500), f0(980) and a0(980), which appear in the two articles discussed in this chapter: that of the eta_c -> eta pi+ pi- decay, and that of the a0(980)-f0(980) mixing in chi_c1 -> pi0 pi0 eta and chi_c1 -> pi0 pi+ pi-. Both works share common features of a method used in an earlier study of the chi_c1 -> eta pi+ pi- decay, which consists in using SU(3) symmetry to see the weight of different trios of pseudoscalars produced in the charmonium decay c cbar -> 123.
In chapter 2 we show a method for studying meson-baryon interactions and looking for new states as poles in the scattering amplitude. We discuss how to extend the local hidden gauge approach to the charm sector, through the exchange of light vectors with SU(3) symmetry and the heavy quark as spectator. We present three papers: the one on the five Omega_c states recently discovered by the LHCb collaboration, three of them in remarkable agreement with our calculations; then the follow-up article on how to observe these states in the weak decay Omega_b -> Xi_c+ K- pi- and a third one with predictions for Omega_b molecular states.
In chapter 3 we see how triangular singularities can be formed in the decay A -> 1+R, followed by R -> 2+3 and the rescattering 1+2 -> 1'+2'. We see that in the case when there is a resonance from the rescattering, at the same energy corresponding to the singularity, its effect can be seen in the experiment and misinterpreted as a new state. In our first work we study the production and decay of the f1(1285) in pi a0(980) and K* Kbar. We find an enhancement tied to a triangular singularity concluding that the f1(1420) is not a genuine resonance, but the manifestation of these decay modes at higher energies. Next, we study the reaction gamma p -> p pi0 eta paying attention to the two main mechanisms at low energies, gamma p -> Delta(1700) -> eta Delta(1232) or pi N(1535), where the second involves a triangular singularity. Finally, we investigate the Schmid theorem that states the possible triangle singularity developed by the elastic reescattering does not change the cross section provided by the tree level. We investigate the process in terms of the width of the unstable particle produced and determine the violation and the limits for validity of the theorem.
Overall we have shown the importance of the dynamically generated states and how this description should be part of our understanding of the fundamental properties of matter
Triangle singularity in B-→ K-X(3872) ; X→ ππ+π- and the X(3872) mass
No full textWe evaluate the contribution to the X(3872) width from a triangle mechanism in which the X decays into DD¯ - cc, then the D(D¯ ) decays into Dπ (D¯ π) and the DD¯ fuse to produce ππ. This mechanism produces an asymmetric peak from a triangle singularity in the ππ invariant mass with a shape very sensitive to the X mass. We evaluate the branching ratios for a reaction where this effect can be seen in the B→ Kπππ reaction and show that the determination of the peak in the invariant mass distribution of ππ is all that is needed to determine the X mass. Given the present uncertainties in the X mass, which do not allow to know whether the DD¯ state is bound or not, measurements like the one suggested here should be most welcome to clarify this issue
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