Aceti, F., Bayar, M., Oset, E., Martinez Torres, A., Khemchandani, K. P., Dias, J. M., et al. (2014). Prediction of an I=1 D(D)over-bar* state and relationship to the claimed Z(c)(3900), Z(c)(3885). Phys. Rev. D, 90(1), 016003–13pp.
Abstract: We study here the interaction of D (D) over bar* in the isospin I = 1 channel in light of recent theoretical advances that allow us to combine elements of the local hidden gauge approach with heavy quark spin symmetry. We find that the exchange of light q (q) over bar is Okubo-Zweig-Iizuka (OZI) suppressed and thus we concentrate on the exchange of heavy vectors and of two pion exchange. The latter is found to be small compared to the exchange of heavy vectors, which then determines the strength of the interaction. A barely D (D) over bar* bound state decaying into eta(c)rho and pi J/psi is found. At the same time we reanalyze the data of the BESIII experiment on e(+)e(-) -> pi(+/-)(D (D) over bar*)(-/+), from where a Z(c)(3885) state was claimed, associated to a peak in the (D (D) over bar*)(-/+) invariant mass distribution close to threshold, and we find the data compatible with a resonance with mass around 3875 MeV and width around 30 MeV. We discuss the possibility that this and the Z(c)(3900) state found at BESIII, reconfirmed at 3894 MeV at Belle, or 3885 MeV at CLEO, could all be the same state and correspond to the one that we find theoretically.
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Xiao, C. W., Bayar, M., & Oset, E. (2012). Prediction of D*-multi-rho states. Phys. Rev. D, 86(9), 094019–10pp.
Abstract: We present a study of the many-body interaction between a D* and multi-rho. We use an extrapolation to SU(4) of the hidden gauge formalism, which produced dynamically the resonances f(2)(1270) in the rho rho interaction and D-2* (2460) in the rho D* interaction. We then let a third particle, rho, D*, or a resonance, collide with them, evaluating the scattering amplitudes in terms of the fixed center approximation of the Faddeev equations. We find several clear resonant structures above 2800 MeV in the multibody scattering amplitudes. They would correspond to new charmed resonances, D-3*, D-4*, D-5*, and D-6*, which are not yet listed in the Particle Data Group, which would be analogous to the rho(3)(1690), f(4)(2050), rho(5)(2350), f(6)(2510) and K-3*(1780), K-4*(2045), K-5*(2380) described before as multi-rho and K*-multi-rho states, respectively.
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Bayar, M., Pavao, R., Sakai, S., & Oset, E. (2018). Role of the triangle singularity in Lambda(1405) production in the pi(-) p -> K-0 pi Sigma and pp -> pK(+) pi Sigma processes. Phys. Rev. C, 97(3), 035203–12pp.
Abstract: We have investigated the cross section for the pi(-) p -> K-0 pi Sigma and pp -> pK(+) pi Sigma reactions, paying attention to a mechanism that develops a triangle singularity. The triangle diagram is realized by the decay of a N* to K* Sigma and the K* decay into pi K, and the pi Sigma finally merges into Lambda (1405). The mechanism is expected to produce a peak around 2140 MeV in the K Lambda (1405) invariant mass. We found that a clear peak appears around 2100 MeV in the K Lambda (1405) invariant mass, which is about 40 MeV lower than the expectation, and that is due to the resonance peak of a N* resonance which plays a crucial role in the K* Sigma production. The mechanism studied produces the peak of the Lambda (1405) around or below 1400 MeV, as is seen in the pp -> pK(+) pi Sigma HADES experiment.
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Ikeno, N., Bayar, M., & Oset, E. (2018). Semileptonic decay of B-c(-) into X (3930), X (3940), X (4160). Eur. Phys. J. C, 78(5), 429–7pp.
Abstract: We study the semileptonic decay of B-c(-) meson into & Unknown;l(-) and the isospin zero X (3930) (2(++)), X(3940) (0(++)), X (4160) (2(++)) resonances. We look at the reaction from the perspective that these resonaces appear as dynamically generated from the vector-vector interaction in the charm sector, and couple strongly to D*& Unknown;D* and D-s*& Unknown;D-s*. We also look into the B-c(-) -> & Unknown;(l)l(-) D*& Unknown;* and B-c(-) -> & Unknown;(l)l(-) D-s*& Unknown;(s)* reactions close to threshold and relate the D*& Unknown;* and D-s*& Unknown;(s)* mass distribution to the rate of production of the X resonances.
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Azizi, K., Bayar, M., Ozpineci, A., Sarac, Y., & Sundu, H. (2012). Semileptonic transition of Sigma(b) to Sigma in light cone QCD sum rules. Phys. Rev. D, 85(1), 016002–8pp.
Abstract: We use distribution amplitudes of the light Sigma baryon and the most general form of the interpolating current for heavy Sigma(b) baryon to investigate the semileptonic Sigma(b) -> Sigma l(+)l(-) transition in light cone QCD sum rules. We calculate all 12 form factors responsible for this transition and use them to evaluate the branching ratio of the considered channel. The order of branching fraction shows that this channel can be detected at LHC.
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Bayar, M., Fernandez-Soler, P., Sun, Z. F., & Oset, E. (2016). States of rho B*(B)over-bar* with J=3 within the fixed center approximation to Faddeev equations. Eur. Phys. J. A, 52(4), 106–8pp.
Abstract: In this work we stu dy the rho B*(B) over bar* three-body system solving the Faddeev equations in the fixed center approximation. We assume the B*B* system forming a cluster, and in terms of the two-body rho B* unitarized scattering amplitudes in the local hidden gauge approach we find a new I(J(PC)) = 1(3(--)) state. The mass of the new state corresponds to a two-particle invariant mass of the rho B* system close to the resonant energy of the B-2(*) (5747), indicating that the role of this J = 2 resonance is important in the dynamical generation of the new state.
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Bayar, M., Ren, X. L., & Oset, E. (2015). States of rho D*(D)over-bar* with J=3 within the fixed center approximation to the Faddeev equations. Eur. Phys. J. A, 51(5), 61–9pp.
Abstract: 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 = 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 = 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 = 0 around 4000MeV, and a less bound narrow state with I = 1 around 4200 MeV.
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Martinez Torres, A., Bayar, M., Jido, D., & Oset, E. (2012). Strategy to find the two Lambda (1405) states from lattice QCD simulations. Phys. Rev. C, 86(5), 055201–13pp.
Abstract: Theoretical studies within the chiral unitary approach, and recent experiments, have provided evidence of the existence of two isoscalar states in the region of the Lambda(1405). In this paper we use the same chiral approach to generate energy levels in a finite box. In a second step, assuming that these energies correspond to lattice QCD results, we devise the best strategy of analysis to obtain the two states in the infinite-volume case, with sufficient precision to distinguish them. We find out that by using energy levels obtained with asymmetric boxes and/or with a moving frame, with reasonable errors in the energies, one has a successful scheme to get the two Lambda(1405) poles.
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Bayar, M., Molina, R., Oset, E., Liu, M. Z., & Geng, L. S. (2024). Subtleties in triangle loops for Ds+ → ρ+ η → π+ π0 η in a0(980) production. Phys. Rev. D, 109(7), 076027–7pp.
Abstract: We address a general problem in the evaluation of triangle loops stemming from the consideration of the range of the interaction involved in some of the vertices, as well as the energy dependence of the width of some unstable particles in the loop. We find sizeable corrections from both effects. We apply that to a loop relevant to the D + s -> pi + pi 0 eta decay, and find reductions of about a factor of 4 in the mass distribution of invariant mass of the pi eta in the region of the a 0 ( 980 ) . The method used is based on the explicit analytical evaluation of the q 0 integration in the d 4 q loop integration, using Cauchy 's residues method, which at the same time offers an insight on the convergence of the integrals and the effect of form factors and cutoffs.
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Bayar, M., & Oset, E. (2013). The (K)over-barNN system revisited including absorption. Nucl. Phys. A, 914, 349–353.
Abstract: We present the Fixed Center Approximation (FCA) to the Faddeev equations for the (K) over bar NN system with S = 0, including the charge exchange mechanisms in the (K) over bar rescattering. The system appears bound by about 35 MeV and the width, omitting two body absorption, is about 50 MeV. We also evaluate the (K) over bar absorption width in the bound (K) over bar NN system by employing the FCA to account for (K) over bar rescattering on the NN cluster. The width of the states found previously for S = 0 and S = 1 is found now to increase by about 30 MeV due to the (K) over bar NN absorption, to a total value of about 80 MeV.
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