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17 latex pages.- 7 figures.- 2 tables.- Some typos corrected ; 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. ; We thank Callum Wilkinson for making the results of Ref. [63] available to us. This research has been supported by the Spanish Ministerio de Economia y Competitividad (MINECO) and the European fund for regional development (FEDER) under Contracts No. FIS2011-28853-C02-01, No. FIS2011-28853-C02-02, No. FPA2013-47443-C2-2-P, No. FIS2014-51948-C2-1-P, No. FIS2014-51948-C2-2-P, No. FIS2014-57026-REDT, and No. SEV-2014-0398; by Generalitat Valenciana under Contract No. PROMETEOII/2014/0068; and by the European Union HadronPhysics3 project, Grant No. 283286. ; Peer reviewed

The pion mass dependence of the nucleon mass within the covariant SU(2) baryon chiral perturbation theory both without and with explicit Delta(1232) degrees of freedom up to order p(4) is investigated. By fitting to a comprehensive set of lattice QCD data in 2 and 2 + 1 flavors from several collaborations, for pion masses M-pi < 420 MeV, we obtain low energy constants of natural size that are compatible with pion-nucleon scattering data. Our results are consistent with the rather linear pion mass dependence showed by lattice QCD. In the 2 flavor case we have also performed simultaneous fits to nucleon mass and sigma(pi N) data. As a result of our analysis, which encompasses the study of finite volume corrections and discretization effects, we report a value of sigma(pi N) = 41(5)(4) MeV in the 2 flavor case and sigma(pi N) = 52(3)(8) MeV for 2 + 1 flavors, where the inclusion of the Delta(1232) resonance changes the results by around 9 MeV. In the 2 flavor case we are able to set independently the scale for lattice QCD data, given by a Sommer scale of r(0) = 0.493(23) fm. ; We thank Doug Toussaint for making the new MILC data available to us. We are also grateful to Jose M. Alarcon, Michele Della Morte, Jambul Gegelia, Juan Nieves and Vladimir Pascalutsa for useful discussions. The work by L. A. R., T. L. and M. V. V. has been supported by the Spanish Ministerio de Economia y Competitividad and European FEDER funds under Contracts No. FIS2011-28853-C02-01 and No. FIS2011-28853-C02-02, Generalitat Valenciana under Contract No. PROMETEO/2009/0090 and the EU Hadron-Physics3 project, Grant No. 283286. J. M. C. acknowledges support from the Science Technology and Facilities Council (STFC) under Grant No. ST/J000477/1, the Spanish Government and FEDER funds under Contract No. FIS2011-28853-C0201 and the Grants No. FPA2010-17806 and Fundacion Seneca No. 11871/PI/09. ; Peer reviewed

We study single kaon production off the nucleon induced by electrons (positrons) i.e., e(-) (e(+)) + N -> v(e) ((v) over bar (e)) + (K) over bar (K) + N' at low energies. The possibility of observing these processes with the high luminosity beams available at TJNAF and Mainz is discussed, taking into account that the strangeness conserving electromagnetic reactions have a higher energy threshold for (K) over bar (K) production. The calculations are done using 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 Sigma*(1385) ; We acknowledge useful discussions with P. Achenbach and S. K. Singh. M. R. A. wishes to acknowledge the financial support from the University of Valencia and Aligarh Muslim University under the academic exchange program and also to the C. S. I. R., Government of India for S. R. F. This work has been partially supported by the DST, Government of India under Grant No. SR/S2/HEP-0001/2008, the Spanish Ministerio de Economia y Competitividad and European FEDER funds under Contracts No. FIS2011-28853-C02-01 and No. FIS2011-24149, by Generalitat Valenciana under Contract No. PROMETEO/2009/0090, by Junta de Andalucia Grant No. FQM-225 and by the EU Hadron-Physics2 project, Grant No. 227431. I. R. S. also wishes to acknowledge the financial support from MIUR Grant No. PRIN-2009TWL3MX. ; Peer reviewed

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. ; We want to acknowledge discussions with P. Stamoulis. This work is partly supported by DGICYT Contract No. FIS 2006-03438, the Generalitat Valenciana in the program Prometeo and the EU Integrated Infrastructure Initiative Hadron Physics Project under contract RII3-CT-2004-506078. I.R.S. acknowledges support from the Ministerio de Educación. M.R.A. wishes to acknowledge the financial support from the University of Valencia and Aligarh Muslim University under the academic exchange program and also to the DST, Government of India for the financial support under the grant SR/S2/HEP-0001/2008. ; Peer reviewed