Session J12: Neutrinos and Physics Beyond the Standard Model

Live

The Deep Underground Neutrino Experiment (DUNE) is a next-generation long-baseline neutrino experiment. Projected to start taking data in the 2020s, DUNE involves a 1.2 MW neutrino beam from Fermilab’s Long Baseline Neutrino Facility (LBNF) and a 40-kt liquid argon TPC Far Detector at the Sanford Underground Research Facility (SURF), coupled with a Near Detector (ND) placed 574 m downstream of the neutrino beam production target. The DUNE ND is crucial for controlling systematic uncertainties at the Far Detector, in particular for the CP violation measurement, and will itself be an important source of data for investigating neutrino-interaction physics. While the conceptual design of the DUNE ND is largely finalized, detailed simulation studies are required for optimizing the DUNE ND configuration details. In this talk, we will discuss a DUNE ND geometry created using the General Geometry Description (GGD) software, which allows easy manipulation of detector geometries and configurations. This geometry is currently in use by the DUNE ND Software Group for GENIE, an MC neutrino interaction event generator, sample generation and subsequent simulation studies.   

Live

Evolutionary algorithms borrow from biology the concepts of mutation and selection to approach complex problems more efficiently than traditional techniques. The GENETIS project uses genetic algorithms to develop antenna designs with higher sensitivity to radio impulses from ultra-high energy neutrino interactions than current designs. We attempt to improve on antenna designs used in current experiments, using geometric constraints imposed by a narrow hole in deep ice. By integrating the XFdtd finite-difference time domain modeling program with simulations of neutrino experiments, we are able to assign a fitness score that is based on neutrino sensitivities. We will report initial results from this project.   

Live

The LHC interaction region is a very compact source of tau neutrinos from $D_s$ and $B$ meson decays. For angles close to the beam direction, these prompt decays dominate neutrino production. We use next-to-leading order QCD production of heavy quarks with initial partonic $k_T$ smearing, followed by heavy quark fragmentation and decay to neutrinos, to present a new calculation of the spectrum of neutrinos in the very forward region. For definiteness, we evaluate the number of events in a detector of 1 m radius and length of 1 m of lead target located 480 m from the LHC interaction point. With this approach, thousands of tau neutrino plus antineutrino events are predicted for an LHC integrated luminosity of 3000 fb$^{-1}$. The impacts on the tau neutrino energy distribution from $k_T$ smearing and from perturbative QCD uncertainties associated with the renormalization and factorization scales are assessed in the context of comparisons with LHCb data on double differential cross sections in transverse momentum and rapidity for $D_s$ production. We illustrate the potential for an experiment that measures tau neutrino interactions with this 480 m oscillation baseline to constrain a 3+1 active-sterile mixing scenario with a fourth neutrino mass of order tens of eV.   

Live

LUX-ZEPLIN (LZ) is a new multi-ton liquid xenon time projection chamber for dark matter direct detection.~ The central volume of LZ will be both low background and low threshold, sensitive to electron recoils down to roughly 1 keV.~ At these energies, electron recoils of pp solar neutrinos will be a significant fraction of the total event rate, and LZ will be sensitive to any non-standard model effects that may enhance the neutrino-electron scattering cross section at low energies.~ We present a sensitivity study using simulation data, predicting LZ{\&}apos;s significant sensitivity to neutrino magnetic moment and effective milli-charge.   

Live

The impressive improvement by the ACME Collaboration in 2018 suggests the presence of a new electron Yukawa coupling, ρee, that accompanies an extra top Yukawa coupling, ρtt, where the latter is responsible for electroweak baryogenesis (EWBG). In the context of the general two Higgs doublet model that permits such extra Yukawa couplings, we elucidate an exquisite cancellation among dangerous diagrams for the electron electric dipole moment, broadening the solution space for EWBG ρtt-driven. The cancellation calls for the new Yukawa couplings to have hierarchical structures that echo the observed pattern of the Standard Model Yukawa couplings.   

Live

The integrated $\eta$ and $\eta'$ meson samples collected in earlier experiments have been about ~$10^9$ events limiting considerably the search for such rare decays. A new experiment, REDTOP, is being proposed, to Fermilab and CERN, with the goal of collecting more than $10^{13}$ eta/year ($10^{11}$ eta'/year) for studying of rare processes. Such statistics is sufficient for investigating symmetry violations, and for searches of new particles BSM. Recent studies have indicated that REDTOP has vey good sensitivity to processes that couple to the Standard Model through three portals: the vector, the scalar and the axion portal. REDTOP is aiming at running at Fermilab with a staged approach. In Phase-I, the experiment will be located in the APS hall and receive protons at 1.8-3.5GeV from the Delivery Ring. In Phase-II, an upgraded version of the detector will be proposed for running at PIP-II, where the $\eta$ mesons will be produced with tagging. The kinematics will be fully closed and a the experiment will be sensitive to long-lived particles by measuring the missin 4-momentum of the event. The physics program, the accelerator systems and the detector for REDTOP will be discussed during the presenta   

Fitting neutrino masses in a realistic intersecting D-braneworld

The correct quark and charged lepton mass matrices along with a nearly correct CKM matrix may be naturally accommodated in a Pati-Salam model constructed from intersecting D6 branes on a $T^6/(Z_2 \times Z_2)$ orientifold. Also, near-tribimaximal mixing for neutrinos may arise naturally due to the structure of the Yukawa matrices. Consistency with the quark and charged lepton mass matrices in combination with obtaining near-tribimaximal mixing fixes the Dirac neutrino mass matrix completely. Then, applying the seesaw mechanism for different choices of right-handed neutrino masses and running the obtained neutrino parameters down to the electroweak scale via the RGEs, we are able to make predictions for the neutrino masses and mixing angles. We obtain lepton mixing angles which are close to the observed values, $\theta_{12} =33.8^{\circ}\pm1.2^{\circ}$, $\theta_{23}=46.9^{\circ}\pm0.9^{\circ}$, and $\theta_{13}=8.56^{\circ}\pm0.20^{\circ}$. In addition, the neutrino mass-squared differences are found to be $\Delta m^2_{32} = 0.0025\pm0.0001$ eV$^2$ and $\Delta m^2_{21} = 0.000075\pm0.000003$ eV with $m_1=0.0150\pm0.0002$ eV, $m_2=0.0173\pm0.0002$ eV, and $m_3=0.053\pm 0.002$ eV so that $\sum_i m_i = 0.085\pm0.002$ eV, consistent with experimental observations.   

Explaining the ATOMKI X17 particle within the Standard Model

In 2016, Krasznahorkay $et$ $al.$ at the Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI), announced data indicating the existence of a hypothetical gauge boson. In 2019 Krasznahorkay $et$ $al.$ announced additional evidence indicating the existence of the 'hypothetic X17 particle' in the form of $e^+e^-$ pairs from the M0 transition depopulating the 21.01 MeV $0^-$ state in $^4$He, with 7.2 $\sigma$ significance. We critically analyze the original results of ATOMKI as well as new evidence in the context of Standard Model processes, in particular interference effects between non-resonant decay amplitudes and higher-order QED corrections.   

Magnetic Moment of Leptons in a Medium

We show that the magnetic moment of leptons is significantly modified at finite temperature and density as compared to the corresponding vacuum value. We compare the magnetic~moment of all different leptons near nucleosynthesis temperature to show the relevance of the calculations with the early universe. It is shown that the significance of~thermal corrections depends on the temperature of the universe and the respective lepton~mass. In the early universe, particle mass was growing quadratically with temperature which~affects the corresponding value of magnetic moment.