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Wang, E., Liang, W. H., & Oset, E. (2021). Analysis of the e(+)e(-) -> J/psi D(D)over-bar reaction close to the threshold concerning claims of a chi(c0)(2P) state. Eur. Phys. J. A, 57(1), 38–9pp.
Abstract: We analyze the D (D) over bar mass distribution from a recent Belle experiment on the e(+)e(-) -> J/.D (D) over bar reaction, and show that the mass distribution divided by phase sp(c)e does not have a clear peak above the D (D) over bar threshold that justifies the experimental claim of chi(c0)(2P) state from those data. Then we use a unitary formalismwith coupled channels D+ D-, D-0 (D) over bar (0), D-s(D) over bar (s), and eta eta, with some of the interactions taken from a theoretical model, and use the data to fix other parameters. We then show that, given the poor quality of the data, we can get different fits leading to very different D (D) over bar amplitudes, some of them supporting a D (D) over bar bound state and others not. The main conclusion is that the claim for the chi(c0)(2P) state, already included in the PDG, is premature, but refined data can provide very valuable information on the D (D) over bar scattering amplitude. As side effects, we warn about the use of a Breit-Wigner amplitude parameterization close to threshold, and show that the D-s(D) over bar (s) channel plays an important role in this reaction.
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Wang, E., Li, H. S., Liang, W. H., & Oset, E. (2021). Analysis of the gamma gamma -> D(D)over-bar reaction and the D(D)over-bar bound state. Phys. Rev. D, 103(5), 054008–10pp.
Abstract: In this work, we investigate the reaction of gamma gamma -> D (D) over bar, taking into account the S-wave D (D) over bar final state interaction. By fitting to the D (D) over bar, invariant mass distributions measured by the Belle and BABAR Collaborations, we obtain a good reproduction of the data by means of a D (D) over bar, amplitude that produces a bound D (D) over bar, statewith isospin I = 0 close to threshold. The error bands of the fits indicate, however, that more precise data on this reaction are needed to be more assertive about the position and width of such a state.
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Renteria-Estrada, D. F., Hernandez-Pinto, R. J., & Sborlini, G. F. R. (2021). Analysis of the Internal Structure of Hadrons Using Direct Photon Production. Symmetry-Basel, 13(6), 942–10pp.
Abstract: Achieving a precise description of the internal structure of hadrons is crucial for deciphering the hidden properties and symmetries of fundamental particles. It is a hard task since there are several bottlenecks in obtaining theoretical predictions starting from first principles. In order to complement highly accurate experiments, it is necessary to use ingenious strategies to impose constraints from the theory side. In this article, we describe how photons can be used to unveil the internal structure of hadrons. We explore how to describe NLO QCD plus LO QED corrections to hadron plus photon production at colliders and discuss the impact of these effects on the experimental measurements.
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Gonzalez-Iglesias, D., Esperante, D., Gimeno, B., Blanch, C., Fuster-Martinez, N., Martinez-Reviriego, P., et al. (2023). Analysis of the Multipactor Effect in an RF Electron Gun Photoinjector. IEEE Trans. Electron Devices, 70(1), 288–295.
Abstract: The objective of this work is the evaluation of the risk of suffering a multipactor discharge within an RF electron gun photoinjector. Photoinjectors are a type of source for intense electron beams, which are the main electron source for synchrotron light sources, such as free-electron lasers. The analyzed device consists of 1.6 cells and it has been designed to operate at the S-band. Besides, around the RF gun there is an emittance compensation solenoid, whose magnetic field prevents the growth of the electron beam emittance, and thus the degradation of the properties of the beam. The multipactor analysis is based on a set of numerical simulations by tracking the trajectories of the electron cloud in the cells of the device. To reach this aim, an in-house multipactor code was developed. Specifically, two different cases were explored: with the emittance compensation solenoid assumed to be off and with the emittance compensation solenoid in operation. For both the cases, multipactor simulations were carried out exploring different RF electric field amplitudes. Moreover, for a better understanding of the multipactor phenomenon, the resonant trajectories of the electrons and the growth rate of the electrons population are investigated.
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Bayar, M., Ikeno, N., & Oset, E. (2020). Analysis of the psi (4040) and psi (4160) decay into D-(*()) (D)over-bar(()*()), D-s(()*()) (D)over-bar(s)(()*()). Eur. Phys. J. C, 80(3), 222–9pp.
Abstract: We have performed an analysis of the e+e--> D(*) data in the region of the psi(4040) and psi(4160) resonances which have a substantial overlap and require special care. By using the P-3(0) model to relate the different D(*)(D) over bar(*) production modes, we make predictions for production of these channels and compare with experiment and other theoretical approaches. As a side effect we find that these resonances qualify largely as c (c) over bar states and theweight of the meson-meson components in the wave function is very small.
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