Neutrino flavor changing neutral currents and stellar collapse

Flavor changing neutral current interactions are predicted in some extensions of the Standard Model. We discuss a process by which a neutrino can change flavor by scattering with a quark. We show how the stellar collapse environment is sensitive to neutrino flavor changing scattering on heavy nuclei. In particular, when this interaction is included in the stellar collapse model, the dynamics of the core's evolution and outcome of collapse are drastically changed. © 2006 American Institute of Physics

Stellar collapse dynamics with neutrino flavor changing neutral currents

We perform one-zone simulations of the infall epoch of a presupernova stellar core in the presence of neutrino flavor changing scattering interactions. Our calculations give a self-consistent assessment of the relationship between flavor changing rates and the reduction in electron fraction and redistribution of initial electron lepton number among the neutrino flavors. We discuss and include in our calculations subnuclear density medium corrections for flavor changing scattering coherence factors. We find that flavor changing couplings >3×10-4 in either the νeνμ or νeντ channels result in a dynamically significant reduction in the core electron fraction relatively soon after neutrino trapping and well before the core reaches nuclear matter density. © 2007 The American Physical Society

Neutrino flavor changing neutral currents and stellar collapse

Flavor changing neutral current interactions are predicted in some extensions of the Standard Model. We discuss a process by which a neutrino can change flavor by scattering with a quark. We show how the stellar collapse environment is sensitive to neutrino flavor changing scattering on heavy nuclei. In particular, when this interaction is included in the stellar collapse model, the dynamics of the core's evolution and outcome of collapse are drastically changed. © 2006 American Institute of Physics

Stellar collapse dynamics with neutrino flavor changing neutral currents

We perform one-zone simulations of the infall epoch of a presupernova stellar core in the presence of neutrino flavor changing scattering interactions. Our calculations give a self-consistent assessment of the relationship between flavor changing rates and the reduction in electron fraction and redistribution of initial electron lepton number among the neutrino flavors. We discuss and include in our calculations subnuclear density medium corrections for flavor changing scattering coherence factors. We find that flavor changing couplings >3×10-4 in either the νeνμ or νeντ channels result in a dynamically significant reduction in the core electron fraction relatively soon after neutrino trapping and well before the core reaches nuclear matter density. © 2007 The American Physical Society

Flavor changing supersymmetry interactions in a supernova

We consider for the first time flavor changing neutral currents (FCNC's) in the infall stage of stellar collapse. We take as an example R-Parity violating interactions of the minimal standard supersymmetric model involving neutrinos and quarks. However, our considerations extend to other kinds of flavor changing neutrino reactions as well. We examine non-forward neutrino scattering processes on heavy nuclei and free nucleons in the supernova core. This investigation has led to four principal original discoveries/products: (1) first calculation of neutrino flavor changing cross sections for spin 1/2 (e.g., free nucleon) and spin 0 nuclear targets; (2) discovery of nuclear mass number squared (A2) coherent amplification of neutrino-quark FCNC's; (3) analysis of FCNC-induced alteration of electron capture and weak/nuclear equilibrium in the collapsing core; and (4) generalization of the calculated cross sections (mentioned in 1) for the case of hot heavy nuclei to be used in collapse/supernova and neutrino transport simulations. The scattering processes that we consider allow electron neutrinos to change flavor during core collapse, thereby opening holes in the Ve sea, which allows electron capture to proceed and results in a lower core electron fraction Ye. A lower Ye implies a lower homologous core mass, a lower shock energy, and a greater nuclear photo-disintegration burden for the shock. In addition, unlike the standard supernova model, the core now could have net muon and/or tau lepton numbers. These effects could be significant even for supersymmetric couplings below current experimental bounds. © 2005 Elsevier B.V. All rights reserved