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Bruschini, R., & Gonzalez, P. (2021). Strong decays of the lowest bottomonium hybrid within an extended Born-Oppenheimer framework. Eur. Phys. J. C, 81(1), 74–9pp.
Abstract: We analyze the decays of the theoretically predicted lowest bottomonium hybrid H(1P) to open bottom two-meson states. We do it by embedding a quark pair creation model into the Born-Oppenheimer framework which allows for a unified, QCD-motivated description of bottomonium hybrids as well as bottomonium. A new 1P1 decay model for H(1P) comes out. The same analysis applied to bottomonium leads naturally to the well-known 3 P0 decay model. We show that H(1P) and the theoretically predicted bottomonium state Upsilon (5S), whose calculated masses are close to each other, have very different widths for such decays. A comparison with data from Upsilon (10860), an experimental resonance whose mass is similar to that of Upsilon (5S) and H(1P), is carried out. Neither a Upsilon (5S) nor a H(1P) assignment can explain the measured decay widths. However, a Upsilon (5S)-H(1P) mixing may give account of them supporting previous analyses of dipion decays of Upsilon (10860) and suggesting a possible experimental evidence of H(1P).
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Bruschini, R., & Gonzalez, P. (2023). chi(c1)(2p): an overshadowed charmoniumlike resonance. J. High Energy Phys., 02(2), 216–23pp.
Abstract: A thorough study of the J(PC )= 1(++) elastic D0 & macr;D*(0) and D+D*(-) scattering, where the form of the meson-meson interaction is inferred from lattice QCD calculations of string breaking, is carried out for center-of-mass energies up to 4 GeV. We show that the presence of chi c1(3872), which can be naturally assigned to either a bound or virtual charmoniumlike state close below the D0 & macr;D*0 threshold, can overshadow a quasiconventional charmoniumlike resonance lying above threshold. This makes difficult the experimental detection of this resonance through the D0 & macr;D*(0) and D+D*(-) channels, despite being its expected main decay modes. We analyze alternative strong and electromagnetic decay modes. Comparison with existing data shows that this resonance may have already been observed through its decay to omega J/psi.
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Bruschini, R., & Gonzalez, P. (2019). Quark model description of psi(4260). Phys. Rev. C, 99(4), 045205–9pp.
Abstract: From lattice indications we follow a Born-Oppenheimer approximation to build a quark-antiquark static potential for J(Pc) = 1(--) charmonium states below their first S-wave meson-meson threshold. We show that a good description of the mass and decay properties of the experimentally well established psi(4260) resonance is feasible.
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Bruschini, R., & Gonzalez, P. (2019). Radiative decays in bottomonium beyond the long wavelength approximation. Phys. Rev. D, 100(7), 074001–13pp.
Abstract: We revisit the nonrelativistic quark model description of electromagnetic radiative decays in bottomonium. We show that even for the simplest spectroscopic quark model the calculated widths can be in good agreement with data once the experimental masses of bottomonium states and the photon energy are properly implemented in the calculation. For transitions involving the lower lying spectral states this implementation can be easily done via the long wavelength approximation. For transitions where this approximation does not apply we develop a new method of implementing the experimental energy dependencies.
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Bruschini, R., & Gonzalez, P. (2020). Radiative decays in charmonium beyond the p/m approximation. Phys. Rev. D, 101(1), 014027–16pp.
Abstract: We analyze the theoretical description of radiative decays in charmonium. We use an elementary emission decay model to build the most general electromagnetic transition operator. We show that accurate results for the widths can be obtained from a simple quark potential model reasonably fitting the spectroscopy if the complete form of the operator is used instead of its standard p/m approximation and the experimental masses are properly implemented in the calculation.
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