Gran, R., Nieves, J., Sanchez, F., & Vicente Vacas, M. J. (2013). Neutrino-nucleus quasi-elastic and 2p2h interactions up to 10 GeV. Phys. Rev. D, 88(11), 113007–10pp.
Abstract: We extend to 10 GeV results from a microscopic calculation of charged-current neutrino-nucleus reactions that do not produce a pion in the final state. For the class of events coming from neutrino interactions with two nucleons producing two holes (2p2h), limiting the calculation to three-momentum transfers less than 1.2 GeV produces a two-dimensional distribution in momentum and energy transfer that is roughly constant as a function of energy. The cross section for 2p2h interactions approximately scales with the number of nucleons for isoscalar nuclei, similar to the quasi-elastic cross section. When limited to momentum transfers below 1.2 GeV, the cross section is 26% of the quasi-elastic cross section at 3 GeV, but 14% if we neglect a Delta(1232) resonance absorption component. The same quantities are 33% and 17% for antineutrinos. For the quasi-elastic interactions, the full nuclear model with long range correlations produces an even larger, but approximately constant distortion of the shape of the four-momentum transfer at all energies above 2 GeV. The 2p2h enhancement and long-range correlation distortions to the cross section for these interactions are significant enough they should be observable in precision experiments to measure neutrino oscillations and neutrino interactions at these energies, but also balance out and produce less total distortion than each effect does individually.
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Ledwig, T., Martin Camalich, J., Geng, L. S., & Vicente Vacas, M. J. (2014). Octet-baryon axial-vector charges and SU(3)-breaking effects in the semileptonic hyperon decays. Phys. Rev. D, 90(5), 054502–16pp.
Abstract: The octet-baryon axial-vector charges and the g(1)/f(1) ratios measured in the semileptonic hyperon decays are studied up to O(p(3)) using the covariant baryon chiral perturbation theory with explicit decuplet contributions. We clarify the role of different low-energy constants and find a good convergence for the chiral expansion of the axial-vector charges of the baryon octet, g(1)(0), with O(p(3)) corrections typically around 20% of the leading ones. This is a consequence of strong cancellations between different next-to-leading- order terms. We show that considering only nonanalytic terms is not enough and that analytic terms appearing at the same chiral order play an important role in this description. The same effects still hold for the chiral extrapolation of the axial-vector charges and result in a rather mild quark-mass dependence. As a result, we report a determination of the leading-order chiral couplings, D = 0.623(61)(17) and F = 0.441(47)(2), as obtained from a completely consistent chiral analysis up to O(p(3)). Furthermore, we note that the appearance of an unknown low-energy constant precludes the extraction of the proton octet charge from semileptonic decay data alone, which is relevant for an analysis of the composition of the proton spin.
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Ren, X. L., Oset, E., Alvarez-Ruso, L., & Vicente Vacas, M. J. (2015). Antineutrino induced Lambda(1405) production off the proton. Phys. Rev. C, 91(4), 045201–11pp.
Abstract: We have studied the strangeness-changing antineutrino-induced reactions (v) over bar (l)p -> l(+)phi B, with phi B = K(-)p, (K) over bar (0)n, pi(0)Lambda, pi(0)Sigma(0), eta Lambda, eta Sigma(0), pi(+)Sigma(-), pi(-)Sigma(+), K+Xi(-), and K-0 Xi(0), using a chiral unitary approach. These ten coupled channels are allowed to interact strongly, using a kernel derived from the chiral Lagrangians. This interaction generates two Lambda(1405) poles, leading to a clear single peak in the pi Sigma invariant mass distributions. At backward scattering angles in the center-of-mass frame, (nu) over bar (mu)p -> mu(+)pi(0)Sigma(0) is dominated by the Lambda(1405) state at around 1420 MeV while the lighter state becomes relevant as the angle decreases, leading to an asymmetric line shape. In addition, there are substantial differences in the shape of pi Sigma invariant mass distributions for the three charge channels. If observed, these differences would provide valuable information on a claimed isospin I = 1, strangeness S = -1 baryonic state around 1400 MeV. Integrated cross sections have been obtained for the pi Sigma and (K) over barN channels and the impact of unitarization in the results has been investigated. The number of events with Lambda(1405) excitation in (nu) over bar μp collisions in the recent antineutrino run at the Main Injector Experiment for nu-A (MINER nu A) has also been obtained. We find that this reaction channel is relevant enough to be investigated experimentally and to be taken into account in the simulation models of future experiments with antineutrino beams.
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Alvarez-Ruso, L., Hernandez, E., Nieves, J., & Vicente Vacas, M. J. (2016). Watson's theorem and the N Delta(1232) axial transition. Phys. Rev. D, 93(1), 014016–16pp.
Abstract: We present a new determination of the N Delta axial form factors from neutrino induced pion production data. For this purpose, the model of Hernandez et al. [Phys. Rev. D 76, 033005 (2007)] is improved by partially restoring unitarity. This is accomplished by imposing Watson's theorem on the dominant vector and axial multipoles. As a consequence, a larger C-5(A) (0), in good agreement with the prediction from the off-diagonal Goldberger-Treiman relation, is now obtained.
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Sun, Z. F., & Vicente Vacas, M. J. (2016). Masses of doubly charmed baryons in the extended on-mass-shell renormalization scheme. Phys. Rev. D, 93(9), 094002–8pp.
Abstract: In this work, we investigate the mass corrections of the doubly charmed baryons up to (NLO)-L-2 in the extended-on-mass-shell (EOMS) renormalization scheme, comparing with the results of heavy baryon chiral perturbation theory. We find that the terms from the heavy baryon approach are a subset of those obtained in the EOMS scheme. By fitting the lattice data, we can determine the parameters (m) over tilde, alpha, c(1) and c(7) from the Lagrangian, while in the heavy baryon approach no information on c(1) can be obtained from the baryons mass. Correspondingly, the masses of m(Xi cc) and m(Omega cc) are predicted, in the EOMS scheme, extrapolating the results from different values of the charm quark and the pion masses of the lattice QCD calculations.
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