[Paper Review] Hypothesis about semi-weak interaction and experiments with solar neutrinos

L. M. Slad|arXiv (Cornell University)|Feb 11, 2015

Neutrino Physics Research33 references3 citations

TL;DR

This paper proposes a semi-weak interaction mediated by a massless pseudoscalar boson that causes electron neutrinos to undergo ~10 collisions with nucleons in the Sun, flipping their chirality and modifying their energy spectrum. This model explains the observed solar neutrino fluxes in $^{37}$Cl, $^{71}$Ga, elastic scattering, and deuteron disintegration with excellent agreement to experimental data, offering an alternative to neutrino oscillations with a single free parameter.

ABSTRACT

A new concept is proposed to solve the solar neutrino problem, that is based on a hypothesis about the existence of semi-weak interaction of electron neutrinos with nucleons mediated by massless pseudoscalar bosons. Owing to about 10 collisions of a solar neutrino with nucleons of the Sun, the fluxes of left- and right-handed solar neutrinos at the Earth surface are approximately equal, and their spectrum is changed in comparison with the one at the production moment. The postulated model with one free parameter provides a good agreement between the calculated and experimental characteristics of the processes with solar neutrinos: ${}^{37}{ m Cl} ightarrow {}^{37}{ m Ar}$, ${}^{71}{ m Ga} ightarrow {}^{71}{ m Ge}$, $ν_{e} e^{-} ightarrow ν_{e} e^{-}$, and $ν_{e}D ightarrow e^{-}pp$.

Motivation & Objective

• To resolve the solar neutrino problem by proposing a new interaction mechanism that explains discrepancies between standard solar model predictions and experimental observations.
• To provide a unified explanation for multiple solar neutrino experiments, including $^{37}$Cl, $^{71}$Ga, elastic scattering, and deuteron disintegration, without relying on neutrino oscillations.
• To demonstrate that the observed fluxes and energy dependencies in experiments can be explained by neutrino scattering in the Sun's inhomogeneous medium via a semi-weak interaction.
• To quantify the coupling strength of the proposed interaction using observed neutrino fluxes and collision statistics in the solar interior.

Proposed method

• Proposes a semi-weak interaction mediated by a massless pseudoscalar boson coupling electron neutrinos to nucleons, with a coupling product $ g_{\nu_e ps}g_{N ps}/4\pi = (3.2 \pm 0.2) \times 10^{-5} $.
• Models neutrino propagation through the Sun as a short-term Brownian motion with ~10 collisions per neutrino, leading to chirality flipping between left- and right-handed states.
• Assumes the total cross-section for neutrino-nucleon scattering is energy-independent, preserving the number of collisions across energies.
• Uses energy loss per collision proportional to $ \Delta\omega/\omega \simeq \omega/M $, leading to a softened neutrino spectrum by the time they exit the Sun.
• Calculates effective fluxes for different processes by integrating over the modified neutrino spectrum, accounting for energy-dependent cross sections.
• Compares theoretical predictions for reaction rates in $^{37}$Cl, $^{71}$Ga, $\nu_e e^-$, and $\nu_e D$ processes with experimental data to validate the model.

Experimental results

Research questions

• RQ1 Can the observed solar neutrino fluxes in $^{37}$Cl, $^{71}$Ga, elastic scattering, and deuteron disintegration be explained by a single interaction mechanism without neutrino oscillations?
• RQ2 What is the effect of repeated neutrino-nucleon collisions in the Sun on the neutrino energy spectrum and chirality distribution?
• RQ3 How does the energy dependence of cross sections for different processes interact with the modified neutrino spectrum to reproduce experimental rates?
• RQ4 What is the required coupling strength of a new semi-weak interaction to match observed solar neutrino data?
• RQ5 Why do current oscillation-based models fail to provide a unified, parameterized calculation of all solar neutrino process rates?

Key findings

• The model achieves good agreement between theoretical predictions and experimental data for $^{37}$Cl → $^{37}$Ar, $^{71}$Ga → $^{71}$Ge, $\nu_e e^-$ scattering, and $\nu_e D \to e^- pp$ processes.
• The effective number of neutrino-nucleon collisions in the Sun is estimated to be approximately 10, consistent with the observed energy spectrum softening.
• The product of coupling constants $ g_{\nu_e ps}g_{N ps}/4\pi $ is determined to be $ (3.2 \pm 0.2) \times 10^{-5} $, significantly smaller than electromagnetic or weak coupling constants.
• The energy loss per collision is proportional to $ \omega/M $, leading to a total energy reduction of about 0.3% for neutrinos exiting the Sun, within the theoretical uncertainty of the standard solar model.
• The model explains the observed difference in effective fluxes between $^{8}$B neutrino processes due to differing energy dependencies of cross sections and the modified neutrino spectrum.
• The hypothesis is considered robust, with the probability of accidental agreement being negligible, and offers a logically consistent, alternative explanation to neutrino oscillations.