Nucleon contribution to the neutrino electromagnetic vertex in matter

We calculate the nucleon contribution to the electromagnetic vertex of a neutrino in a background of particles, including the effect of the anomalous magnetic moment of the nucleons. Explicit formulas for the form factors are given in various physical limits of practical interest. Several applications of the results are mentioned, including the effect of an external magnetic field on the dispersion relation of a neutrino in matter.Comment: LaTeX, 18 pages; to appear in PR

Neutrino damping rate at finite temperature and density

A first principle derivation is given of the neutrino damping rate in real-time thermal field theory. Starting from the discontinuity of the neutrino self energy at the two loop level, the damping rate can be expressed as integrals over space phase of amplitudes squared, weighted with statistical factors that account for the possibility of particle absorption or emission from the medium. Specific results for a background composed of neutrinos, leptons, protons and neutrons are given. Additionally, for the real part of the dispersion relation we discuss the relation between the results obtained from the thermal field theory, and those obtained by the thermal average of the forward scattering amplitude.Comment: LaTex Document, 19 pages, 3 figure

Field theory of the photon self-energy in a medium with a magnetic field and the Faraday effect

A convenient and general decomposition of the photon self-energy in a magnetized, but otherwise isotropic, medium is given in terms of the minimal set of tensors consistent with the transversality condition. As we show, the self-energy in such a medium is completely parametrized in terms of nine independent form factors, and they reduce to three in the long wavelength limit. We consider in detail an electron gas with a background magnetic field, and using finite temperature field theory methods, we obtain the one-loop formulas for the form factors, which are exact to all orders in the magnetic field. Explicit results are derived for a variety of physical conditions. In the appropriate limits, we recover the well-known semi-classical results for the photon dispersion relations and the Faraday effect. In more general cases, where the semi-classical treatment or the linear approximation (weak field limit) are not applicable, our formulas provide a consistent and systematic way for computing the self-energy form factors and, from them, the photon dispersion relations.Comment: Revtex, 27 page

Nucleon effects on the photon dispersion relations in matter

We calculate the nucleon contribution to the photon self-energy in a plasma, including the effect of the anomalous magnetic moment of the nucleons. General formulas for the transverse and longitudinal components of the self-energy are obtained and we give explicit results in various limits of physical interest. The formulas are relevant for the study of the photon dispersion relations and the dynamical susceptibility in a nuclear medium such as the core of a supernova, and has implications with regard to the recent suggestion that the Cerenkov process $\nu \to \nu\gamma$ can take place in such a system.Comment: RevTe

Bound on the neutrino magnetic moment from chirality flip in supernovae

For neutrinos with a magnetic moment, we show that the collisions in a hot and dense plasma act as an efficient mechanism for the conversion of $\nu_L$ into $\nu_R$. The production rate for right-handed neutrinos is computed in terms of a resummed photon propagator which consistently incorporates the background effects. Assuming that the entire energy in a supernova collapse is not carried away by the $\nu_R$, our results can be used to place an upper limit on the neutrino magnetic moment $\mu_\nu < (0.1-0.4)\times 10^{-11}\mu_B$Comment: 11 pages, minor changes, new title. Final version to appear in Phys. Rev. D (rapid communication

QED symmetries in real-time thermal field theory

We study the discrete and gauge symmetries of Quantum Electrodynamics at finite temperature within the real-time formalism. The gauge invariance of the complete generating functional leads to the finite temperature Ward identities. These Ward identities relate the eight vertex functions to the elements of the self-energy matrix. Combining the relations obtained from the $Z_2$ and the gauge symmetries of the theory we find that only one out of eight longitudinal vertex functions is independent. As a consequence of the Ward identities it is shown that some elements of the vertex function are singular when the photon momentum goes to zero.Comment: New version as it will appear in Phys RevD 19 pages, RevTex, 1figur

Exploring low-energy neutrino physics with the Coherent Neutrino Nucleus Interaction Experiment

The Coherent Neutrino-Nucleus Interaction Experiment (CONNIE) uses low-noise fully depleted charge-coupled devices (CCDs) with the goal of measuring low-energy recoils from coherent elastic scattering ( CE ν NS ) of reactor antineutrinos with silicon nuclei and testing nonstandard neutrino interactions (NSI). We report here the first results of the detector array deployed in 2016, considering an active mass 47.6 g (eight CCDs), which is operating at a distance of 30 m from the core of the Angra 2 nuclear reactor, with a thermal power of 3.8 GW. A search for neutrino events is performed by comparing data collected with the reactor on (2.1 kg-day) and reactor off (1.6 kg-day). The results show no excess in the reactor-on data, reaching the world record sensitivity down to recoil energies of about 1 keV (0.1 keV electron equivalent). A 95% confidence level limit for new physics is established at an event rate of 40 times the one expected from the standard model at this energy scale. The results presented here provide a new window to low-energy neutrino physics, allowing one to explore for the first time the energies accessible through the low threshold of CCDs. They will lead to new constraints on NSI from the CEνNS of antineutrinos from nuclear reactors.Fil: Aguilar Arevalo, Alexis. Universidad Nacional Autónoma de México; MéxicoFil: Bertou, Xavier Pierre Louis. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Universidad Nacional de Cuyo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Bonifazi, Carla Brenda. Universidade Federal do Rio de Janeiro; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cancelo, Gustavo Indalecio. Fermi National Accelerator Laboratory; Estados UnidosFil: Castañeda, Alejandro. Universidad Nacional Autónoma de México; MéxicoFil: Cervantes Vergara, Brenda. Universidad Nacional Autónoma de México; MéxicoFil: Chavez, Claudio. Universidad Nacional de Asunción; ParaguayFil: D’Olivo, Juan C.. Universidad Nacional Autónoma de México; MéxicoFil: Dos Anjos, João C.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Estrada, Juan. Fermi National Accelerator Laboratory; Estados UnidosFil: Fernandes Neto, Aldo R.. Centro Federal de Educacão Tecnológica Celso Suckow Da Fonseca; BrasilFil: Fernández Moroni, Guillermo. Fermi National Accelerator Laboratory; Estados Unidos. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Foguel, Ana. Universidade Federal do Rio de Janeiro; BrasilFil: Ford, Richard. Fermi National Accelerator Laboratory; Estados UnidosFil: Gonzalez Cuevas, Juan. Universidad Nacional de Asunción; ParaguayFil: Hernández, Pamela. Universidad Nacional Autónoma de México; MéxicoFil: Hernandez, Susana. Fermi National Accelerator Laboratory; Estados UnidosFil: Izraelevitch, Federico Hernán. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kavner, Alexander R.. University of Michigan; Estados UnidosFil: Kilminster, Ben. Universitat Zurich; SuizaFil: Kuk, Kevin. Fermi National Accelerator Laboratory; Estados UnidosFil: Lima, H.P.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Makler, Martín. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Molina, Jorge. Universidad Nacional de Asunción; ParaguayFil: Mota, Philipe. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Nasteva, Irina. Universidade Federal do Rio de Janeiro; BrasilFil: Paolini, Eduardo Emilio. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Romero, Carlos. Universidad Nacional de Asunción; ParaguayFil: Sarkis, Y.. Universidad Nacional Autónoma de México; MéxicoFil: Sofo Haro, Miguel Francisco. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de Cuyo; Argentina. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnol.conicet - Patagonia Norte. Unidad de Adm.territorial; ArgentinaFil: Souza, Iruatã M. S.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Tiffenberg, Javier Sebastian. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Wagner, Stefan. Centro Brasileiro de Pesquisas Físicas; Brasil. Pontifícia Universidade Católica do Rio de Janeiro; Brasi