
Bayar, M., Liang, W. H., Uchino, T., & Xiao, C. W. (2014). Description of rho(1700) as a rho Kappa(sic) system with the fixedcenter approximation. Eur. Phys. J. A, 50(4), 67–10pp.
Abstract: We study the system with the aim to describe the rho(1700) resonance. The chiral unitary approach has achieved success in the description of systems of the light hadron sector. With this method, the system in the isospin sector I = 0, is found to be a dominant component of the f (0)(980) resonance. Therefore, by regarding the system as a cluster, the f (0)(980) resonance, we evaluate the system applying the fixedcenter approximation to the Faddeev equations. We construct the rho K unitarized amplitude using the chiral unitary approach. As a result, we find a peak in the threebody amplitude around 1732 MeV and a width of about 161 MeV. The effect of the width of the rho and f (0)(980) is also discussed. We associate this peak to the rho(1700) which has a mass of 1720 +/ 20MeV and a width of 250 +/ 100 MeV.



Bayar, M., Xiao, C. W., Hyodo, T., Dote, A., Oka, M., & Oset, E. (2012). Energy and width of a narrow I=1/2 DNN quasibound state. Phys. Rev. C, 86(4), 044004–16pp.
Abstract: The energies and widths of DNN quasibound states with isospin I = 1/2 are evaluated in two methods, the fixed center approximation to the Faddeev equation and the variational method approach to the effective onechannel Hamiltonian. The DN interactions are constructed so they dynamically generate the Lambda(c)(2595) (I = 0, J(pi) = 1/2()) resonance state. We find that the system is bound by about 250 MeV from the DNN threshold, root s similar to 3500 MeV. Its width, including both the mesonic decay and the D absorption, is estimated to be about 2040 MeV. The I = 0 DN pair in the DNN system is found to form a cluster that is similar to the Lambda(c)(2595).



Dote, A., Bayar, M., Xiao, C. W., Hyodo, T., Oka, M., & Oset, E. (2013). A narrow quasibound state of the DNN system. Nucl. Phys. A, 914, 499–504.
Abstract: We have investigated a charmed system of DNN (composed of two nucleons and a D meson) by a complementary study with a variational calculation and a Faddeev calculation with fixedcenter approximation (FaddeevFCA). In the present study, we employ a DN potential based on a vectormeson exchange picture in which a resonant A(c)(2595) is dynamically generated as a DN quasibound state, similarly to the A(1405) as a (K) over barN one in the strange sector. As a result of the study of variational calculation with an effective DN potential and three kinds of NN potentials, the DNN(J(pi) =0(), I = 1/2) is found to be a narrow quasibound state below A(c)(2595)N threshold: total binding energy similar to 225 MeV and mesonic decay width similar to 25 MeV. On the other hand, the J(pi) =1() state is considered to be a scattering state of A(c)(2595) and a nucleon. These results are essentially supported by the FaddeevFCA calculation. By the analysis of the variational wave function, we have found a unique structure in the DNN(J(pi) = 0, I = 1/2) such that the D meson stays around the center of the total system due to the heaviness of the D meson.



Feijoo, A., Wang, W. F., Xiao, C. W., Wu, J. J., Oset, E., Nieves, J., et al. (2023). A new look at the Pcs states from a molecular perspective. Phys. Lett. B, 839, 137760–7pp.
Abstract: We have a look at the Pcs states generated from the interaction of (D) over bar(*)Xi(c)('*) coupled channels. We consider the blocks of pseudoscalarbaryon (1/2(+) , 3/2(+)) and vectorbaryon (1/2(+), 3/2(+)), and find 10 resonant states coupling mostly to (D) over bar Xi(c), <(D)*over bar>*Xi(c), (D) over bar Xi(c)' <(DA novel aspect of the work is the realization that the <(Dover bar>Xi(c), (Dover bar>(s) Lambda(c) or (Dover bar>*Xi(c), Ds*Lambda(c) channels, with a strong transition potential, collaborate to produce a larger attraction than the corresponding states <(Dover bar>Xi(c), <(Dover bar>Lambda(c) or (D) over bar*Xi(c), (D) over bar*Lambda(c) appearing in the generation of the strangenessless Pc states, since in the latter case the transition potential between those channels is zero. The extra attraction obtained in the (D) over bar Xi(c), (D) over bar* Xi(c) pairs preclude the association of the Pcs(4338) state coupling mostly to (D) over bar*Xi(c) while the Pcs(4459) is associated to the state found that couples mostly to (D) over bar Xi(c)'. Four more states appear, like in other molecular pictures, and some of the states are degenerate in spin. Counting different spin states we find 10states, which we hope can be observed in the near future.



Holz, S., Plenter, J., Xiao, C. W., Dato, T., Hanhart, C., Kubis, B., et al. (2021). Towards an improved understanding of eta > gamma*gamma *. Eur. Phys. J. C, 81(11), 1002–15pp.
Abstract: We argue that highquality data on the reaction e(+)e() > pi(+) pi() eta will allow one to determine the doublyvirtual form factor eta > gamma*gamma* in a modelindependent way with controlled accuracy. This is an important step towards a reliable evaluation of the hadronic lightbylight scattering contribution to the anomalous magnetic moment of themuon. When analyzing the existing data for e(+) e() > pi(+) pi() eta for total energies squared k(2) > 1GeV(2), we demonstrate that the effect of the a(2) meson provides a natural breaking mechanism for the commonly employed factorization ansatz in the doublyvirtual form factor Feta gamma*gamma* (q(2), k(2)). However, better data are needed to draw firm conclusions.



Li, H. P., Yi, J. Y., Xiao, C. W., Yao, D. L., Liang, W. H., & Oset, E. (2024). Correlation function and the inverse problem in the BD interaction. Chin. Phys. C, 48(5), 053107–7pp.
Abstract: We study the correlation functions of the (BD+)D0, (B+D0) system, which develops a bound state of approximately 40MeV, using inputs consistent with the Tcc(3875) state. Then, we address the inverse problem starting from these correlation functions to determine the scattering observables related to the system, including the existence of the bound state and its molecular nature. The important output of the approach is the uncertainty with which these observables can be obtained, considering errors in the (BD+)D0, (B+D0) correlation functions typical of current values in correlation functions. We find that it is possible to obtain scattering lengths and effective ranges with relatively high precision and the existence of a bound state. Although the pole position is obtained with errors of the order of 50% of the binding energy, the molecular probability of the state is obtained with a very small error of the order of 6%. All these findings serve as motivation to perform such measurements in future runs of high energy hadron collisions.



Liang, W. H., Uchino, T., Xiao, C. W., & Oset, E. (2015). Baryon states with open charm in the extended local hidden gauge approach. Eur. Phys. J. A, 51(2), 16–14pp.
Abstract: In this paper we examine the interaction of DN and D* N states, together with their coupled channels, by using an extension of the local hidden gauge formalism from the light meson sector, which is based on heavy quark spin symmetry. The scheme is based on the use of the impulse approximation at the quark level, with the heavy quarks acting as spectators, which occurs for the dominant terms where there is the exchange of a light meson. The pion exchange and the WeinbergTomozawa interactions are generalized and with this dynamics we look for states generated from the interaction, with a unitary coupled channels approach that mixes the pseudoscalarbaryon and vectorbaryon states. We find two states with nearly zero width, which are associated to the I > (c) (2595) and I > (c) (2625). The lower state, with J (P) = 1/2(), couples to DN and D* N, and the second one, with J (P) = 3/2(), to D* N. In addition to these two I > (c) states, we find four more states with I = 0, one of them nearly degenerate in two states of J (P) = 1/2, 3/2. Furthermore we find three states in I = 1, two of them degenerate in J = 1/2, 3/2.



Liang, W. H., Xiao, C. W., & Oset, E. (2014). Baryon states with open beauty in the extended local hidden gauge approach. Phys. Rev. D, 89(5), 054023–15pp.
Abstract: In this paper, we examine the interaction of (B) over barN, (B) over bar Delta, (B) over bar *N, and (B) over bar*Delta states, together with their coupled channels, by using a mapping from the light meson sector. The assumption that the heavy quarks act as spectators at the quark level automatically leads us to the results of the heavy quark spin symmetry for pion exchange and reproduces the results of the Weinberg Tomozawa term, coming from light vector exchanges in the extended local hidden gauge approach. With this dynamics we look for states dynamically generated from the interaction and find two states with nearly zero width, which we associate to the A(b)(5912) and A(b)(5920) states. The states couple mostly to (B) over bar *N, which are degenerate with the Weinberg Tomozawa interaction. The difference of masses between these two states, with J = 1/2 and 3/2, respectively, is due to pion exchange connecting these states to intermediate (B) over barN states. In addition to these two A(b) states, we find three more states with I = 0, one of them nearly degenerate in two states of J = 1/2, 3/2. Furthermore, we also find eight more states in I = 1, two of them degenerate in J = 1/2, 3/2, and another two degenerate in J = 1/2, 3/2, 5/2.



Liang, W. H., Xiao, C. W., & Oset, E. (2013). Study of eta K(K)overbar and eta ' K(K)overbar with the fixed center approximation to Faddeev equations. Phys. Rev. D, 88(11), 114024–10pp.
Abstract: In the present work we investigate the threebody systems of eta K (K) over bar and eta'K (K) over bar, by taking the fixed center approximation to Faddeev equations. We find a clear and stable resonance structure around 1490 MeV in the squared eta K (K) over bar scattering amplitude, which is not sensitive to the renormalization parameters. Conversely, we get only an enhancement effect of the threshold in the eta'K (K) over bar amplitude that indicates the difficulty to bind the eta'K (K) over bar system as a consequence of the eta'K interaction being weaker than the eta K one. We associate the eta K (K) over bar state found to the eta(1475).



Lin, J. X., Chen, H. X., Liang, W. H., Xiao, C. W., & Oset, E. (2024). (B)overbars0 → Ds1(2460)+ K, Ds1(2536)+ K and the nature of the two Ds1 resonances. Eur. Phys. J. C, 84(4), 439–8pp.
Abstract: Starting from the molecular picture for the Ds1(2460) and Ds1(2536) resonances, which are dynamically generated by the interaction of coupled channels, the most important of which are the D* K for the Ds1(2460) and DK* for the Ds1(2536), we evaluate the ratio of decay widths for the (B) over bar (0)(s) > Ds1(2460)(+) K and (B) over bar (0)(s) > Ds1(2536)(+) K decays, the latter of which has been recently investigated by the LHCb collaboration, and we obtain a ratio of the order of unity. The present results should provide an incentive for the related decay into the Ds1(2460) resonance to be performed, which would provide valuable information on the nature of these two resonances.

