<p>We propose an alternative to the axion mechanism for addressing the charge parity (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>) problem in QCD. Our approach involves imposing <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> as an inherent symmetry of the Lagrangian, which is then spontaneously broken. To generate the correct texture for the Yukawa matrices, we introduce a discrete <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="double-struck">Z</mi><mn>2</mn></msub></math> symmetry that is softly broken by the scalar potential. By identifying a benchmark point for the Yukawa couplings that aligns with the measured quark masses, the Cabibbo-Kobayashi-Maskawa matrix, and low-energy flavor-changing constraints, our findings suggest that this model offers a viable solution to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> problem.</p>

Germany

Rodolfo Ferro-Hernández

Italy

Stefano Morisi

Mexico

Eduardo Peinado

Axionless strong <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>C</mi><mi>P</mi></mrow></math> problem solution: The spontaneous <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>C</mi><mi>P</mi></mrow></math>-violation case

New heavy neutral leptons lead to non-unitary effects in models for neutrino masses. Such effects could represent a sign of new physics beyond the Standard Model, leading to observable deviations in neutrino oscillation experiments, lepton flavor violation, and other precision measurements. This work explores the parameter space of the linear and inverse low-scale seesaw models based on flavor symmetries consistent with neutrino oscillation experiments. In particular, we investigated the violation of unitarity when the lepton flavor violation is absent and when only one lepton flavor-violating channel is present.

Jesús Celestino-Ramírez

G. Hernández-Tomé

O. Miranda

Non-unitary limits on different textures for low-scale seesaw models

<p>The observation of the coherent elastic neutrino-nucleus scattering process using reactor antineutrinos offers a unique opportunity to probe the Standard Model and explore beyond the Standard Model scenarios. This study reports on the latest results from the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>CONUS</mi><mo>+</mo><mtext>experiment</mtext></mrow></math> conducted at the Leibstadt nuclear power plant in Switzerland. The CONUS collaboration reports <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>395</mn><mo>±</mo><mn>106</mn></math> events detected from reactor antineutrinos with an exposure of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>327</mn><mtext> </mtext><mtext> </mtext><mi>kg</mi><mo>·</mo><mi>days</mi></mrow></math>, utilizing high-purity germanium detectors operated at sub-keV thresholds. A <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>χ</mi><mn>2</mn></msup></math>-based statistical analysis was performed on these results, incorporating systematic uncertainties. This analysis was used to extract the weak mixing angle, establish a limit on the neutrino magnetic moment, and impose constraints on neutrino nonstandard interactions using reactor antineutrinos. The results confirm the potential of coherent elastic neutrino-nucleus scattering experiments in the study of fundamental neutrino properties and probing new physics.</p>

M. Alpízar-Venegas

L.J. Flores

E. Vázquez-Jáuregui

Exploring the standard model and beyond from the evidence of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>CE</mi><mi>ν</mi><mi>NS</mi></mrow></math> with reactor antineutrinos in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>CONUS</mi><mo>+</mo></mrow></math>

In the minimal Scotogenic model with fermionic dark matter, the neutrino Yukawa matrix is fine-tuned to satisfy current bounds on <math><mi>μ</mi><mo>→</mo><mi>e</mi><mi>γ</mi></math> while producing dark matter through thermal freeze-out. One way to avoid this bound is to open a new annihilation channel for dark matter (DM) with a scalar field that breaks the lepton number spontaneously. This introduces a physical Goldstone boson <math><mi>a</mi></math>, which can constitute a light relic and opens up the lepton flavor violating channel <math><mi>μ</mi><mo>→</mo><mi>e</mi><mi>a</mi></math>. In this work, we introduce a model that contains the new annihilation channel for fermionic dark matter but avoids the introduction of the Goldstone boson by using a discrete <math><msub><mi>Z</mi><mn>4</mn></msub></math> instead of a continuous symmetry. In this way, cosmological constraints on the light relic and experimental limits on lepton flavor violating decays to the Goldstone boson are avoided. We analyze the experimental viability of the model, identifying the region of parameter space where lepton flavor violating constraints are not saturated, DM has the correct relic density, and DM direct detection experiments are sensitive to the DM candidate.

Taiwan

Leon M.G. de la Vega

Israel

Patrick J. Fitzpatrick

Rolando Martinez-Ramirez

Leon M. G. de la Vega

Dark matter for Majorana neutrinos in a <math><mrow><msub><mrow><mi>Z</mi></mrow><mrow><mn>4</mn></mrow></msub></mrow></math> symmetry

In this work we analyze the scenario where a MeV scale <math><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></math> gauge boson can explain the deficit in the diffuse ultrahigh-energy (UHE) astrophysical neutrino spectrum observed in IceCube, as well as the discrepancy between experimental and <math><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> scattering data-driven Standard Model calculations of the muon anomalous magnetic moment. We map the parameter space of the model where the elastic resonant s-channel scattering of UHE neutrinos with the cosmic neutrino background, mediated by the new <math><msup><mi>Z</mi><mo>′</mo></msup></math>, can improve the description of the observed cascade and track spectra over the no-scattering hypothesis. Comparing to recent NA64-<math><mi>μ</mi></math> results, we find that some part of the parameter space remains unexplored, but at a data volume of <math><msup><mn>10</mn><mn>11</mn></msup></math> muons on target NA64-<math><mi>μ</mi></math> will completely probe this region.

United States

José Wudka

<math><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></math> solution to the IceCube ultrahigh-energy neutrino deficit in light of NA64

The quantization of a massive spin-<math><mn>1</mn><mo>/</mo><mn>2</mn></math> field that satisfies the Klein-Gordon equation is studied. The framework is consistent, provided it is formulated as a pseudo-Hermitian quantum field theory by the redefinition of the dual field and the identification of an operator that modifies the inner product of states in Hilbert space to preserve a real energy spectrum and unitary evolution. Since the fermion field has mass dimension one, the theory admits renormalizable fermion self-interactions.

Julio Olmos

Carlos A. Vaquera-Araujo

Quantization of second-order fermions

New light gauge bosons can affect several low-energy experiments, such as atomic parity violation or colliders. Here, we explore the possibility that a dark sector is charged under a new U(1) gauge symmetry, and the portal to the Standard Model is through a Z − Z′ mass mixing. In our approach, breaking the new gauge symmetry is crucial to generate neutrino masses. We investigate the parameter space to reproduce neutrino masses, the correct dark matter relic abundance, and to produce the observed core-like DM distribution in galactic centers.

Leon Vega

Neutrino masses and self-interacting dark matter with mass mixing Z − Z′ gauge portal

The hierarchy in scale between atmospheric and solar neutrino mass splittings is investigated through two distinct neutrino mass mechanisms from tree-level and one-loop-level contributions. We demonstrate that the minimal discrete dark matter mechanism contains the ingredients for explaining this hierarchy. This scenario is characterized by adding new RH neutrinos and SU(2)-doublet scalars to the Standard Model as triplet representations of an A 4 flavor symmetry. The A 4 symmetry breaking, which occurs at the electroweak scale, leads to a residual ℤ2 symmetry responsible for the dark matter stability and dictates the neutrino phenomenology. Finally, we show that to reproduce the neutrino mixing angles correctly, it is necessary to violate CP in the scalar potential.

Chile

Cesar Bonilla

Johannes Herms

Spain

Omar Medina

Discrete dark matter mechanism as the source of neutrino mass scales

The sensitivity to new physics of a low threshold scintillating argon bubble chamber measuring coherent elastic neutrino-nucleus scattering in reactors is reported. Namely, light scalar mediators, sterile neutrino oscillations, unitarity violation, and nonstandard interactions are studied. The results indicate that this detector could be able to set stronger constraints than current limits set by the recent COHERENT measurements. Considering the best scenario, a 100 kg detector located 30 m from a <math><mrow><mn>2000</mn><mtext> </mtext><mtext> </mtext><msub><mrow><mi>MW</mi></mrow><mrow><mi>t</mi><mi>h</mi></mrow></msub></mrow></math> reactor, a sterile neutrino search would cover most of the space parameter allowed from the reactor antineutrino anomaly fit. Unitarity violation studies could set constraints on <math><msub><mi>α</mi><mn>11</mn></msub></math>, more stringent than the current oscillation experiments fit. A low threshold argon detector with very low backgrounds has the potential to explore new physics in different scenarios and set competitive constraints.

E. Alfonso-Pita

L. J. Flores

New physics searches in a low threshold scintillating argon bubble chamber measuring coherent elastic neutrino-nucleus scattering in reactors

We examine the potential to probe generalized neutrino interactions (GNIs), exotic effective couplings due to new physics interactions beyond the Standard Model, in the coherent-elastic neutrino-nucleus scattering experiments in light of the latest COHERENT-CsI and -LAr data. Our analysis focuses on scalar-, vector-, and tensor-flavored GNI parameters. A combined analysis has been made to constrain these exotic couplings for the CsI and LAr detector. We further add the projected forthcoming reactor-based scintillating bubble chamber detector to examine these couplings. It has been observed that the addition of reactor data strongly constrained electron flavor GNIs.

Newton Nath

<math><mrow><mi>CE</mi><mi>ν</mi><mi>NS</mi></mrow></math> as a probe of flavored generalized neutrino interactions