Beyond Tree Level with Solar Neutrinos: Towards Measuring the Flavor Composition and CP Violation

After being produced as electron neutrinos (<math altimg="si1.svg"><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub></math>), solar neutrinos partially change their flavor to <math altimg="si2.svg"><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub></math> and <math altimg="si3.svg"><msub><mrow><mi>ν</mi></mrow><mrow><mi>τ</mi></mrow></msub></math> en route to Earth. Although the flavor ratio of the <math altimg="si1.svg"><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub></math> flux to the total flux has been well measured, the <math altimg="si4.svg"><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub><mo>:</mo><msub><mrow><mi>ν</mi></mrow><mrow><mi>τ</mi></mrow></msub></math> composition has not yet been experimentally probed. In this work we investigate the potential of the next-generation experiments for measuring the <math altimg="si4.svg"><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub><mo>:</mo><msub><mrow><mi>ν</mi></mrow><mrow><mi>τ</mi></mrow></msub></math> flavor ratio by utilizing flavor-dependent radiative corrections in the cross sections for <math altimg="si2.svg"><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub></math> and <math altimg="si3.svg"><msub><mrow><mi>ν</mi></mrow><mrow><mi>τ</mi></mrow></msub></math> scattering. Since the transition probabilities of <math altimg="si1.svg"><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub></math> to <math altimg="si2.svg"><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub></math> and <math altimg="si3.svg"><msub><mrow><mi>ν</mi></mrow><mrow><mi>τ</mi></mrow></msub></math> depend on the leptonic CP phase, we also investigate the sensitivity to the CP phase and show that a statistical significance of <math altimg="si5.svg"><mo>∼</mo><mn>1</mn><mi>σ</mi></math> could be reached through precision measurements of solar neutrino spectra.