<p>In this work, we investigate in a quantitative way how much radiative corrections to the matter potential for neutrino oscillations can impact the sensitivity to neutrino mass ordering in long-baseline accelerator experiments. Using numerical simulations for the future experiment DUNE, we find that the statistical significance for excluding the incorrect mass ordering can be enhanced by about <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.4</mn><mi>σ</mi></math> if a one-loop correction of 2.0%—based on the Fermi coupling constant <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>G</mi><mi>μ</mi></msub></math> derived from measurements of muon lifetime—is included. The radiative corrections at one-loop level lead to resolving the neutrino mass ordering at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>5</mn><mi>σ</mi></math> confidence level 4–9 days earlier than at tree level. In contrast, the sensitivity to leptonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation in DUNE is essentially unchanged. Finally, we emphasize that one-loop corrections should be incorporated into analyses of future neutrino oscillation data in a consistent and systematic manner.</p>

China

Jihong Huang

Sweden

Tommy Ohlsson

Sampsa Vihonen

Shun Zhou

Effects of the matter potential at one-loop level on neutrino oscillations in long-baseline experiments

By introducing three right-handed neutrino singlets, the popular canonical seesaw mechanism is able to simultaneously explain the tiny masses of Majorana neutrinos and the baryon asymmetry of the Universe. In this paper, we provide an explicit calculation in this model with the help of the Wigner-like parametrization. We work in a special ansatz where both <math altimg='si1.svg'><msubsup><mrow><mi mathvariant='bold'>m</mi></mrow><mrow><mi mathvariant='normal'>D</mi></mrow><mrow><mi mathvariant='normal'>&#8224;</mi></mrow></msubsup><msub><mrow><mi mathvariant='bold'>m</mi></mrow><mrow><mi mathvariant='normal'>D</mi></mrow></msub></math> and <math altimg='si2.svg'><msubsup><mrow><mi mathvariant='bold'>m</mi></mrow><mrow><mi mathvariant='normal'>R</mi></mrow><mrow><mi mathvariant='normal'>&#8224;</mi></mrow></msubsup><msub><mrow><mi mathvariant='bold'>m</mi></mrow><mrow><mi mathvariant='normal'>R</mi></mrow></msub></math> are diagonal, with <math altimg='si3.svg'><msub><mrow><mi mathvariant='bold'>m</mi></mrow><mrow><mi mathvariant='normal'>D</mi></mrow></msub></math> and <math altimg='si4.svg'><msub><mrow><mi mathvariant='bold'>m</mi></mrow><mrow><mi mathvariant='normal'>R</mi></mrow></msub></math> being accordingly the Dirac and Majorana neutrino mass matrices, and <math altimg='si5.svg'><mo stretchy='false'>[</mo><msubsup><mrow><mi mathvariant='bold'>m</mi></mrow><mrow><mi mathvariant='normal'>D</mi></mrow><mrow><mi mathvariant='normal'>&#8224;</mi></mrow></msubsup><msub><mrow><mi mathvariant='bold'>m</mi></mrow><mrow><mi mathvariant='normal'>D</mi></mrow></msub><mo>,</mo><msubsup><mrow><mi mathvariant='bold'>m</mi></mrow><mrow><mi mathvariant='normal'>R</mi></mrow><mrow><mi mathvariant='normal'>&#8224;</mi></mrow></msubsup><msub><mrow><mi mathvariant='bold'>m</mi></mrow><mrow><mi mathvariant='normal'>R</mi></mrow></msub><mo stretchy='false'>]</mo><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn mathvariant='bold'>0</mn></math> holds. Physical observables can be exactly calculated without any approximation, where three light Majorana neutrino masses <math altimg='si6.svg'><msub><mrow><mi>m</mi></mrow><mrow><mi>i</mi></mrow></msub></math>, leptonic mixing angles <math altimg='si7.svg'><msub><mrow><mi>&#952;</mi></mrow><mrow><mi>i</mi><mi>j</mi></mrow></msub></math>, CP-violating phases <math altimg='si8.svg'><mo stretchy='false'>{</mo><mi>&#948;</mi><mo>,</mo><mi>&#961;</mi><mo>,</mo><mi>&#963;</mi><mo stretchy='false'>}</mo></math>, and three rotation angles <math altimg='si9.svg'><msub><mrow><mi>&#977;</mi></mrow><mrow><mi>i</mi></mrow></msub></math> describing the hierarchy between electroweak and seesaw scales are chosen as input parameters. For demonstration, we evaluate the branching fractions of the lepton-flavor-violating decays of charged leptons and the CP-violating asymmetries in the resonant thermal leptogenesis. The model parameters are constrained by the latest experimental limits.

Experimental constraints on seesaw parameters in the Wigner-like parametrization

<p>In this paper, we perform a complete calculation of the differential cross section for elastic neutrino-electron scattering at the one-loop level in the Standard Model (SM), by using up-to-date values of relevant input parameters in the on-shell renormalization scheme. A careful comparison with the calculation done by Sarantakos, Sirlin, and Marciano more than forty years ago in the same scheme is carried out, and an excellent agreement is found if the same values of input parameters are taken. Then we apply our results to compute the event rates for the detection of reactor antineutrinos in both JUNO and TAO experiments, which are now under construction and will soon be in operation. It should be emphasized that one-loop radiative corrections in the SM must be taken into account in the first place when searching for possible new-physics effects in the coming era of precision neutrino physics.</p>

Elastic neutrino-electron scattering at the one-loop level in the standard model

We point out that the observed pattern of lepton flavor mixing can be well described by a proper nearest-neighbor expansion of a constant <math><mn>3</mn><mo>×</mo><mn>3</mn></math> unitary matrix in powers of a small parameter characterizing the fine effect of μ-τ permutation symmetry breaking. We take an example of this kind for illustration, and provide complete discussions on the usefulness in the study of leptonic CP violation and unitarity triangles in matter.

A nearest-neighbor expansion of lepton flavor mixing in powers of the - Permutation Symmetry Breaking Effect

When neutrinos are propagating in ordinary matter, their coherent forward scattering off background particles results in the so-called Mikheyev-Smirnov-Wolfenstein (MSW) matter potential, which plays an important role in neutrino flavor conversions. In this paper, we present a complete one-loop calculation of the MSW matter potential in the Standard Model. First, we carry out the one-loop renormalization of the Standard Model in the on-shell scheme, where the electromagnetic fine-structure constant <math><mrow><mi>α</mi></mrow></math>, the weak gauge-boson masses <math><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>W</mi></mrow></msub></mrow></math> and <math><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>Z</mi></mrow></msub></mrow></math>, the Higgs-boson mass <math><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>h</mi></mrow></msub></mrow></math> and the fermion masses <math><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>f</mi></mrow></msub></mrow></math> are chosen as input parameters. Then, the finite corrections to the scattering amplitudes of neutrinos with the electrons and quarks are calculated, and the one-loop MSW matter potentials are derived. Adopting the latest values of all physical parameters, we find that the relative size of one-loop correction to the charged-current matter potential of electron-type neutrinos or antineutrinos turns out to be 6%, whereas that to the neutral-current matter potential of all-flavor neutrinos or antineutrinos can be as large as 8%. The calculations are also performed in the <math><mrow><mover><mrow><mtext>MS</mtext></mrow><mrow><mo>¯</mo></mrow></mover></mrow></math> scheme and compared with previous results in the literature.

Mikheyev-Smirnov-Wolfenstein matter potential at the one-loop level in the Standard Model

We improve the Monte-Carlo based QCD sum rules by introducing the rigorous Hölder-inequality-determined sum rule window and a Breit-Wigner type parametrization for the phenomenological spectral function. In this improved sum rule analysis methodology, the sum rule analysis window can be determined without any assumptions on OPE convergence or the QCD continuum. Therefore, an unbiased prediction can be obtained for the phenomenological parameters (the hadronic mass and width etc.). We test the new approach in the ρ meson channel with re-examination and inclusion of αs corrections to dimension-4 condensates in the OPE. We obtain results highly consistent with experimental values. We also discuss the possible extension of this method to some other channels.

Qi-Nan Wang

Canada

Zhu-Feng Zhang

T.G. Steele

Hong-Ying Jin

Zhuo-Ran Huang

A comprehensive revisit of the ρ meson with improved Monte-Carlo based QCD sum rulesSupported by NSFC (11175153, 11205093, 11347020), Open Foundation of the Most Important Subjects of Zhejiang Province, and K. C. Wong Magna Fund in Ningbo University, TGS is Supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), Z. F. Zhang and Z. R. Huang are Grateful to the University of Saskatchewan for its Warm Hospitality