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Rafi Alam, M., Ruiz Simo, I., Sajjad Athar, M., & Vicente Vacas, M. J. (2010). Weak kaon production off the nucleon. Phys. Rev. D, 82(3), 033001–8pp.
Abstract: The weak kaon production off the nucleon induced by neutrinos is studied at the low and intermediate energies of interest for some ongoing and future neutrino oscillation experiments. This process is also potentially important for the analysis of proton decay experiments. We develop a microscopical model based on the SU(3) chiral Lagrangians. The basic parameters of the model are f pi, the pion decay constant, Cabibbo's angle, the proton and neutron magnetic moments, and the axial vector coupling constants for the baryons octet, D and F, that are obtained from the analysis of the semileptonic decays of neutron and hyperons. The studied mechanisms are the main source of kaon production for neutrino energies up to 1.2 to 1.5 GeV for the various channels and the cross sections are large enough to be amenable to be measured by experiments such as Minerva and T2K.
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Yamagata-Sekihara, J., Cabrera, D., Vicente Vacas, M. J., & Hirenzaki, S. (2010). Formation of phi Mesic Nuclei. Prog. Theor. Phys., 124(1), 147–162.
Abstract: We consider the structure and formation of the phi mesic nuclei to investigate the experimental feasibility of the observation of signals of the phi mesic nucleus formation. phi mesic nuclei are considered to be very important objects to study the in-medium modification of the phi-meson spectral function at finite density. We consider ((p) over bar, phi), (gamma, p) and (pi(-), n) reactions to produce a phi-meson inside the nucleus and evaluate the effects of its medium modifications to the reaction cross sections. We also estimate the consequences of the uncertainties of the in-medium (K) over bar self-energy to the phi-nucleus interaction. We find that it may be possible to see peak structures in the reaction spectra for the strong attractive potential cases. On the other hand, for strong absorptive interaction cases with relatively weak attraction, it is very difficult to observe clear peaks and we may need to know the spectrum shape in a wide energy region to deduce the properties of phi.
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Martin Camalich, J., Geng, L. S., & Vicente Vacas, M. J. (2010). Lowest-lying baryon masses in covariant SU(3)-flavor chiral perturbation theory. Phys. Rev. D, 82(7), 074504–7pp.
Abstract: We present an analysis of the baryon-octet and -decuplet masses using covariant SU(3)-flavor chiral perturbation theory up to next-to-leading order. Besides the description of the physical masses we address the problem of the lattice QCD extrapolation. Using the PACS-CS Collaboration data we show that a good description of the lattice points can be achieved at next-to-leading order with the covariant loop amplitudes and phenomenologically determined values for the meson-baryon couplings. Moreover, the extrapolation to the physical point up to this order is found to be better than the linear one given at leading-order by the Gell-Mann-Okubo approach. The importance that a reliable combination of lattice QCD and chiral perturbation theory may have for hadron phenomenology is emphasized with the prediction of the pion-baryon and strange-baryon sigma terms.
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Sarkar, S., Sun, B. X., Oset, E., & Vicente Vacas, M. J. (2010). Dynamically generated resonances from the vector octet-baryon decuplet interaction. Eur. Phys. J. A, 44(3), 431–443.
Abstract: We study the interaction of the octet of vector mesons with the decuplet of baryons using Lagrangians of the hidden gauge theory for vector interactions. The unitary amplitudes in coupled channels develop poles that can be associated with some known baryonic resonances, while there are predictions for new ones at the energy frontier of the experimental research. The work offers guidelines on how to search for these resonances.
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Hernandez, E., Nieves, J., Valverde, M., & Vicente Vacas, M. J. (2010). N-Delta(1232) axial form factors from weak pion production. Phys. Rev. D, 81(8), 085046–5pp.
Abstract: The N Delta axial form factors are determined from neutrino induced pion production ANL and BNL data by using a theoretical model that accounts both for background mechanisms and deuteron effects. We find violations of the off-diagonal Goldberger-Treiman relation at the level of 2 sigma which might have an impact in background calculations for T2K and MiniBooNE low energy neutrino oscillation precision experiments.
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Sajjad Athar, M., Ruiz Simo, I., & Vicente Vacas, M. J. (2011). Nuclear medium modification of the F2(x, Q^2) structure function. Nucl. Phys. A, 857(1), 29–41.
Abstract: We study the nuclear effects in the electromagnetic structure function F-2(x, Q(2)) in the deep inelastic lepton nucleus scattering process by taking into account Fermi motion, binding, pion and rho meson cloud contributions. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations. The ratios R-F2(A) (x, Q(2)) = 2F(2)(A)(x, Q(2))/AF(2)(D)(x, Q(2)) are obtained and compared with recent JLab results for light nuclei with special attention to the slope of the x distributions. This magnitude shows a non-trivial A dependence and it is insensitive to possible normalization uncertainties. The results have also been compared with some of the older experiments using intermediate mass nuclei.
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Nieves, J., Ruiz Simo, I., & Vicente Vacas, M. J. (2011). Inclusive charged-current neutrino-nucleus reactions. Phys. Rev. C, 83(4), 045501–19pp.
Abstract: We present a model for weak charged-current induced nuclear reactions at energies of interest for current and future neutrino oscillation experiments. This model is a natural extension of the work in Refs. [1,2], where the quasielastic contribution to the inclusive electron and neutrino scattering on nuclei was analyzed. The model is based on a systematic many-body expansion of the gauge boson absorption modes that includes one, two, and even three-body mechanisms, as well as the excitation of Delta isobars. The whole scheme has no free parameters, besides those previously adjusted to the weak pion production off the nucleon cross sections in the deuteron, since all nuclear effects were set up in previous studies of photon, electron, and pion interactions with nuclei. We have discussed at length the recent charged-current quasielastic MiniBooNE cross section data, and showed that two-nucleon knockout mechanisms are essential to describing these measurements.
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Haider, H., Ruiz Simo, I., Sajjad Athar, M., & Vicente Vacas, M. J. (2011). Nuclear medium effects in nu(nu)-nucleus deep inelastic scattering. Phys. Rev. C, 84(5), 054610–13pp.
Abstract: We study nuclear medium effects in the weak structure functions F(2)(x, Q(2)) and F(3)(x, Q(2)) in the deep inelastic neutrino and antineutrino induced reactions in nuclei. We use a theoretical model for the nuclear spectral functions which incorporates the conventional nuclear effects, such as Fermi motion, binding, and nucleon correlations. We also consider the pion and rho meson cloud contributions calculated from a microscopic model for meson-nucleus self-energies. The calculations have been performed using relativistic nuclear spectral functions. Our results are compared with the experimental data of the NuTeV and the CERN Dortmund Heidelberg Saclay Warsaw (CDHSW) collaborations.
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Rafi Alam, M., Ruiz Simo, I., Sajjad Athar, M., & Vicente Vacas, M. J. (2012). Antineutrino induced antikaon production off the nucleon. Phys. Rev. D, 85(1), 013014–8pp.
Abstract: The charged-current antikaon production off nucleons induced by antineutrinos is studied at low and intermediate energies. We extend here our previous calculation on kaon production induced by neutrinos. We have developed a microscopic model that starts from the SU(3) chiral Lagrangians and includes background terms and the resonant mechanisms associated to the lowest lying resonance in the channel, namely, the Sigma*(1385). Our results could be of interest for the background estimation of various neutrino oscillation experiments like MiniBooNE and SuperK. They can also be helpful for the planned (nu) over bar experiments like MINER nu A, NO nu A, and T2K phase II, and for beta-beam experiments with antineutrino energies around 1 GeV.
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Nieves, J., Ruiz Simo, I., & Vicente Vacas, M. J. (2012). The nucleon axial mass and the MiniBooNE quasielastic neutrino-nucleus scattering problem. Phys. Lett. B, 707(1), 72–75.
Abstract: The charged-current double differential neutrino cross section, measured by the MiniBooNE Collaboration, has been analyzed using a microscopical model that accounts for, among other nuclear effects, long range nuclear (RPA) correlations and multinucleon scattering. We find that MiniBooNE data are fully compatible with the world average of the nucleon axial mass in contrast with several previous analyses which have suggested an anomalously large value. We also discuss the reliability of the algorithm used to estimate the neutrino energy.
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