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Albaladejo, M., Bibrzycki, L., Dawid, S. M., Fernandez-Ramirez, C., Gonzalez-Solis, S., Hiller Blin, A. N., et al. (2022). Novel approaches in hadron spectroscopy. Prog. Part. Nucl. Phys., 127, 103981–75pp.
Abstract: The last two decades have witnessed the discovery of a myriad of new and unexpected hadrons. The future holds more surprises for us, thanks to new-generation experiments. Understanding the signals and determining the properties of the states requires a parallel theoretical effort. To make full use of available and forthcoming data, a careful amplitude modeling is required, together with a sound treatment of the statistical uncertainties, and a systematic survey of the model dependencies. We review the contributions made by the Joint Physics Analysis Center to the field of hadron spectroscopy.
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Hiller Blin, A. N., Fernandez-Ramirez, C., Jackura, A., Mathieu, V., Mokeev, V. I., Pilloni, A., et al. (2016). Studying the P-c(4450) resonance in J/psi photoproduction off protons. Phys. Rev. D, 94(3), 034002–8pp.
Abstract: A resonancelike structure, the P-c(4450), has recently been observed in the J/psi p spectrum by the LHCb Collaboration. We discuss the feasibility of detecting this structure in J/psi photoproduction in the CLAS12 experiment at JLab. We present a first estimate of the upper limit for the branching ratio of the P-c (4450) to J/psi p. Our estimates, which take into account the experimental resolution effects, predict that it will be possible to observe a sizable cross section close to the J/psi production threshold and shed light on the P-c(4450) resonance in the future photoproduction measurements.
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Nys, J., Mathieu, V., Fernandez-Ramirez, C., Hiller Blin, A. N., Jackura, A., Mikhasenko, M., et al. (2017). Finite-energy sum rules in eta photoproduction off a nucleon. Phys. Rev. D, 95(3), 034014–20pp.
Abstract: The reaction gamma N -> eta N is studied in the high-energy regime (with photon lab energies E gamma(lab) > 4 GeV) using information from the resonance region through the use of finite-energy sum rules. We illustrate how analyticity allows one to map the t dependence of the unknown Regge residue functions. We provide predictions for the energy dependence of the beam asymmetry at high energies.
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Rodas, A., Pilloni, A., Albaladejo, M., Fernandez-Ramirez, C., Mathieu, V., & Szczepaniak, A. P. (2022). Scalar and tensor resonances in J/psi radiative decays. Eur. Phys. J. C, 82(1), 80–17pp.
Abstract: We perform a systematic analysis of the J/psi -> gamma pi(0)pi(0) and -> gamma(KSKS0)-K-0 partial waves measured by BESIII. We use a large set of amplitude parametrizations to reduce the model bias. We determine the physical properties of seven scalar and tensor resonances in the 1-2.5 GeV mass range. These include the well known f(0)(1500) and f(0)(1710), that are considered to be the primary glueball candidates. The hierarchy of resonance couplings determined from this analysis favors the latter as the one with the largest glueball component.
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Smith, W. A., Glazier, D. I., Mathieu, V., Albaladejo, M., Albrecht, M., Baldwin, Z., et al. (2023). Ambiguities in partial wave analysis of two spinless meson photoproduction. Phys. Rev. D, 108(7), 076001–12pp.
Abstract: We describe the formalism to analyze the mathematical ambiguities arising in partial-wave analysis of two spinless mesons produced with a linearly polarized photon beam. We show that partial waves are uniquely defined when all accessible observables are considered, for a wave set which includes S and D waves. The inclusion of higher partial waves does not affect our results, and we conclude that there are no mathematical ambiguities in partial-wave analysis of two mesons produced with a linearly polarized photon beam. We present Monte Carlo simulations to illustrate our results.
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Winney, D., Fernandez-Ramirez, C., Pilloni, A., Hiller Blin, A. N., Albaladejo, M., Bibrzycki, L., et al. (2023). Dynamics in near-threshold J/ψ photoproduction. Phys. Rev. D, 108, 054018–15pp.
Abstract: The study of J/ψ photoproduction at low energies has consequences for the understanding of multiple aspects of nonperturbative QCD, ranging from mechanical properties of the proton to the binding inside nuclei and the existence of hidden-charm pentaquarks. Factorization of the photon-c¯c and nucleon dynamics or vector meson dominance are often invoked to justify these studies. Alternatively, open-charm intermediate states have been proposed as the dominant mechanism underlying J/ψ photoproduction. As the latter violates this factorization, it is important to estimate the relevance of such contributions. We analyze the latest differential and integrated photoproduction cross sections from the GlueX and J/ψ−007 experiments. We show that the data can be adequately described by a small number of partial waves, which we parametrize with generic models enforcing low-energy unitarity. The results suggest a non-negligible contribution from open-charm intermediate states. Furthermore, most of the models present an elastic scattering length incompatible with previous extractions based on vector meson dominance and thus call into question its applicability to heavy mesons. Our results indicate a wide array of physics possibilities that are compatible with present data and need to be disentangled.
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