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Romero-Lopez, F., Rusetsky, A., Schlage, N., & Urbach, C. (2021). Relativistic N-particle energy shift in finite volume. J. High Energy Phys., 02(2), 060–52pp.
Abstract: We present a general method for deriving the energy shift of an interacting system of N spinless particles in a finite volume. To this end, we use the nonrelativistic effective field theory (NREFT), and match the pertinent low-energy constants to the scattering amplitudes. Relativistic corrections are explicitly included up to a given order in the 1/L expansion. We apply this method to obtain the ground state of N particles, and the first excited state of two and three particles to order L-6 in terms of the threshold parameters of the two- and three-particle relativistic scattering amplitudes. We use these expressions to analyze the N-particle ground state energy shift in the complex phi (4) theory.
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Romero-Barrientos, J., Marquez Damian, J. I., Molina, F., Zambra, M., Aguilera, P., Lopez-Usquiano, F., et al. (2022). Calculation of kinetic parameters beta eff and L with modified open source Monte Carlo code OpenMC(TD). Nucl. Eng. Technol., 54(3), 811–816.
Abstract: This work presents the methodology used to expand the capabilities of the Monte Carlo code OpenMC for the calculation of reactor kinetic parameters: effective delayed neutron fraction beff and neutron generation time L. The modified code, OpenMC(Time-Dependent) or OpenMC(TD), was then used to calculate the effective delayed neutron fraction by using the prompt method, while the neutron generation time was estimated using the pulsed method, fitting L to the decay of the neutron population. OpenMC(TD) is intended to serve as an alternative for the estimation of kinetic parameters when licensed codes are not available. The results obtained are compared to experimental data and MCNP calculated values for 18 benchmark configurations.
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Rojas, N., Srivastava, R., & Valle, J. W. F. (2019). Simplest scoto-seesaw mechanism. Phys. Lett. B, 789, 132–136.
Abstract: By combining the simplest (3,1) version of the seesaw mechanism containing a single heavy “right-handed” neutrino with the minimal scotogenic approach to dark matter, we propose a theory for neutrino oscillations. The “atmospheric” mass scale arises at tree level from the seesaw, while the “solar” oscillation scale emerges radiatively, through a loop involving the “dark sector” exchange. Such simple setup gives a clear interpretation of the neutrino oscillation lengths, has a viable WIMP dark matter candidate, and implies a lower bound on the neutrinoless double beta decay rate.
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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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Rocha-Moran, P., & Vicente, A. (2019). Lepton flavor violation in a Z ' model for the b -> s anomalies. Phys. Rev. D, 99(3), 035016–10pp.
Abstract: In recent years, several observables associated to semileptonic b -> s processes have been found to depart from their predicted values in the Standard Model, including a few tantalizing hints of lepton flavor universality violation. In this work, we consider an existing model with a massive Z' boson that addresses the anomalies in b -> s transitions and extend it with a nontrivial embedding of neutrino masses. We analyze lepton flavor-violating effects, induced by the nonuniversal interaction associated to the b -> s anomalies and by the new physics associated to the neutrino mass generation, and determine the expected ranges for the most relevant observables.
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Roca, L., & Oset, E. (2021). Scalar resonances in the D+ -> K-K+K+ decay. Phys. Rev. D, 103(3), 034020–9pp.
Abstract: We study theoretically the resonant structure of the double Cabibbo suppressed D+ -> K-K+K+ decay. We start from an elementary production diagram, considered subleading in previous approaches, which cannot produce a final K-K+ pair at the tree level but which we show to be able to provide the strength of the decay through final meson-meson state interaction. The different meson-meson elementary productions are related through SU(3), and the final rescattering is implemented from a suitable implementation of unitary extensions of chiral perturbation theory, which generate dynamically the scalar resonances1 f(0)(980) and a(0)(980). We obtain a good agreement with recent experimental data from the LHCb Collaboration with a minimal freedom in the fit and show the dominance of the a(0)(980) contribution close to the threshold of the K-K+ spectrum.
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Roca, L., Liang, W. H., & Oset, E. (2022). Inconsistency of the data on the K-1(1270) -> pi K-0*(1430) decay width. Phys. Lett. B, 824, 136827–3pp.
Abstract: We show, using the same Lagrangian for the K-1(1270) -> pi K-0*(1430) and K-0*(1430) -> K-1 (1270)pi decays, that the present PDG data on the partial decay width of K-1 (1270) -> pi K-0*(1430) implies a width for K-0*(1430) -> K-1 (1270)pi decay which is about one order of magnitude larger than the total K-0*(1430) width. A discussion on this inconsistency is done, stressing its relationship to the existence of two K-1(1270) states obtained with the chiral unitary theory, which are not considered in the experimental analyses of K pi pi data.
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Rinaldi, M., & Vento, V. (2020). Pure glueball states in a light-front holographic approach. J. Phys. G, 47(5), 055104–12pp.
Abstract: A phenomenological analysis of the scalar glueball and scalar meson spectra is carried out by using the AdS/QCD framework in the bottom-up approach. The resulting spectra are in good agreement for glueballs with lattice QCD results and for mesons with PDG data. We make use of the relation between the mode functions in AdS/QCD and the wave functions in Light-Front QCD to discuss the mixing of glueballs and mesons. The results of our investigation point out that above 2 GeV scalar particles will appear in almost degenerate pairs of unmixed glueball and mesons states leading to an interesting phenomenology whereby gluon dynamics could be well investigated.
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Rinaldi, M., & Vento, V. (2020). Scalar spectrum in a graviton soft wall model. J. Phys. G, 47(12), 125003–16pp.
Abstract: In this study we present a unified phenomenological analysis of the scalar glueball and scalar meson spectra within an AdS/QCD framework in the bottom up approach. For this purpose we generalize the recently developed graviton soft-wall (GSW) model, which has shown an excellent agreement with the lattice QCD glueball spectrum, to a description of glueballs and mesons with a unique energy scale. In this scheme, dilatonic effects, are incorporated in the metric as a deformation of the AdS space. We apply the model also to the heavy meson spectra with success. We obtain quadratic mass equations for all scalar mesons while the glueballs satisfy an almost linear mass equation. Besides their spectra, we also discuss the mixing of scalar glueball and light scalar meson states within a unified framework: the GSW model. To this aim, the light-front (LF) holographic approach, which connects the mode functions of AdS/QCD to the LF wave functions, is applied. This relation provides the probabilistic interpretation required to properly investigate the mixing conditions.
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Rinaldi, M., & Vento, V. (2021). Meson and glueball spectroscopy within the graviton soft wall model. Phys. Rev. D, 104(3), 034016–17pp.
Abstract: The graviton soft wall (GSW) model provides a unified description of the scalar glueball and meson spectra with a unique energy scale. This success has led us to extend the analysis to the description of the spectra of other hadrons. We use this model to calculate masses of the odd and even ground states of glueballs for various spins, and show that the GSW model is able to reproduce the Regge trajectory of these systems. In addition, the spectra of the rho, a(1 )and eta mesons will be addressed. Results are in excellent agreement with current experimental data. Furthermore such an achievement is obtained without any additional parameters. Indeed, the only two parameters appearing in these spectra are those that were previously fixed by the light scalar meson and glueball spectra. Finally, in order to describe the pi meson spectrum, a suitable modification of the dilaton profile function has been included in the analysis to properly take into account the Goldstone realisation of chiral symmetry. The present investigation confirms that the GSW model provides an excellent description of the spectra of mesons and glueballs with only a small number of parameters unveiling a relevant predicting power.
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