Bulletin of the American Physical Society
6th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Sunday–Friday, November 26–December 1 2023; Hawaii, the Big Island
Session L11: Physics Beyond the Standard Model I |
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Chair: Wouter DEKENS, Institute for Nuclear Theory Room: Hilton Waikoloa Village Kings 1 |
Friday, December 1, 2023 9:00AM - 9:15AM |
L11.00001: Constraining Baryon Number Violation with Neutron Stars, Probing Dark Sectors Jeffrey Berryman, Susan V Gardner, Mohammadreza Zakeri Hidden-sector particles with baryon number can give rise to new decay channels of the neutron, mediating apparent baryon violation. |
Friday, December 1, 2023 9:15AM - 9:30AM |
L11.00002: Nucleon Electric Dipole Moments using Lattice Gauge Theory Tanmoy Bhattacharya The standard model of particle physics agrees remarkably well with most experimental results, and yet, is in violent contradiction with our cosmological models: the universe seems too homogeneous and isotropic on large scales, too clumpy on smaller scales and has altogether too much matter. To have a coherent picture of our universe requires us to look for physics beyond the standard model (BSM). One of the most fruitful places to look for this is by studying a very weakly broken symmetry of the standard model: that of invariance under simultaneous charge conjugation and parity flip (CP)—a symmetry that prohibits electric dipole moments (EDMs) of systems with no near-degenerate excitations. A number of experiments are, therefore, looking for EDMs of neutrons and protons and their current limits are squarely in the range that is informative of new physics just beyond the weak scale. Using an effective field theory language, we can parameterize the leading effects of BSM theories in terms of coefficients of CP-violating dimension-5 and 6 operators. In recent years, simulations of lattice Quantum Chromodynamics (QCD) have attempted to evaluate the matrix elements of many of these operators, with mixed success. In this presentation, we will discuss relevant work from our collaboration. |
Friday, December 1, 2023 9:30AM - 9:45AM |
L11.00003: From the Detector Characterization to the Analysis of Commissioning Data of the Nab Experiment Jin Ha Choi Located at the Spallation Neutron Source (SNS) Oak Ridge National Laboratory (ORNL), the Nab experiment aims to test the Standard Model and search for Beyond Standard Model physics through the precision measurement of electron-antineutrino correlation coefficient and Fierz interference term of free neutron beta decay. Kinematics of decay products is reconstructed from measured proton time-of-flight and electron energy, and systematic effects in the energy reconstruction, including Bremsstrahlung energy loss and linearity of the energy calibration, make a sizable addition to the overall systematic uncertainty budget. Using radioactive sources, we have recently performed ex-situ and in-situ characterization of our highly segmented silicon detectors to understand their response functions. The Nab experiment is currently taking commissioning data with silicon detectors installed at both ends of the Nab spectrometer observing neutron decays. I will present, focusing primarily on energy reconstruction, some of the results of our recent detector characterization campaign at ORNL and the commissioning data. |
Friday, December 1, 2023 9:45AM - 10:00AM |
L11.00004: The Polarization and Transmission Test of the nEDM@SNS's Cryogenic Apparatus Marie A Blatnik The nEDM@SNS experiment's aim to measure the neutron's electric dipole moment (nEDM) to the order of 10^-28 e cm requires novel cryogenic-based techniques, such as loading its two measurement cells in situ with ultracold neutrons produced by the downscattering of 9 A neutrons in superfluid 4He and shielding magnetic field variation with a superconducting lead shield. The cryogenic apparatus consists of nested layers, including an inner magnet vessel containing a magnet package for spin manipulation and its flux return layer inside of the superconducting lead shield. A polarization and transmission test was constructed at the Spallation Neutron Source at Oak Ridge National Lab to characterize a 9 A neutron beam passing through the layers of the cryogenic apparatus. This will inform and troubleshoot the sensitivity for the final nEDM@SNS experiment. The construction efforts and measurement status will be presented. |
Friday, December 1, 2023 10:00AM - 10:15AM |
L11.00005: An overview of the MOLLER experiment at Jefferson Lab Devi L Adhikari, Zuhal Seyma Demiroglu The MOLLER experiment aims to carry out a precise measurement of the parity-violating asymmetry from electron-electron scattering in Hall A at Jefferson Lab. The measured asymmetry will be used to precisely determine the weak charge of the electron to a precision of 2.4 % at an average Q2 of 0.0056 GeV2. This measurement results in an ultra-precise determination of the weak mixing angle, an important fundamental parameter of the Standard Model. The measurement will allow us to indirectly search for Physics Beyond the Standard Model, complementing direct searches at high-energy colliders. The experiment is fully funded and is currently in the construction and prototype testing phase. In this talk, I will give an overview of the science, describe the experimental apparatus, and report on the status of the MOLLER construction project. |
Friday, December 1, 2023 10:15AM - 10:30AM |
L11.00006: The Main Detector and Electronics for the MOLLER Experiment Jie Pan The MOLLER (Measurement Of a Lepton Lepton Electroweak Reaction) experiment at Jefferson Lab is designed to measure the parity-violating asymmetry in polarized electron-electron (Moller) scattering. The experimental goal is to measure the predicted 35 parts per billion (ppb) asymmetry to 0.7 ppb, from which the weak mixing angle sin2θW can be determined to approximately 0.1%. At such a high precision, the measurement would provide a sensitive test of the Standard Model and enhance the search for new physics at multi-TeV scale. The experiment will be carried out mainly in integrating mode for asymmetry measurement and periodically in event mode for kinematics and background studies. An array of radiation hard fused-silica Cerenkov detectors is employed to measure the scattered electrons. The detector signals in both operating modes are processed by a set of dedicated electronics. In this talk, I shall provide an overview of the MOLLER main detector system, with an emphasis on its integrating electronics development. |
Friday, December 1, 2023 10:30AM - 10:45AM |
L11.00007: Testing the Main Integrating Detector Design for the MOLLER Experiment Brynne E Blaikie The MOLLER experiment, in preparation at Jefferson Lab, aims to constrain physics beyond the Standard Model by measuring the parity-violating asymmetry of electron-electron (Møller) scattering. By measuring this asymmetry to extreme precision, MOLLER will provide an ultra-precise determination of the weak mixing angle to 0.1% fractional uncertainty. Among the most challenging aspects of the experiment will be the detection of the small asymmetry in the detector signal. The main detectors and electronics chain has undergone several iterations of simulation, prototyping, and testing to optimize event mode and integration mode data collection. This talk will provide an overview of the design and function of the main detector modules, focusing on the Møller electron detectors, with results of recent beam tests. |
Friday, December 1, 2023 10:45AM - 11:00AM |
L11.00008: Design and Testing of the Cherenkov Detector Assembly for the MOLLER Experiment Jonathon R Mott, Larry Bartoszek, Sayak Chatterjee, Krishna S Kumar The Measurement of a Lepton-Lepton Electroweak Reaction (MOLLER) experiment plans to measure the parity-violating asymmetry of longitudinally polarized electron-electron (møller) scattering. The experiment uses an 11 GeV electron beam impinging on a liquid hydrogen target. Scattered electrons are then momentum analyzed by a magnetic spectrometer before being intercepted by a cylindrical array of radiation-hard fused silica Cherenkov detectors. This array is divided into 6 rings, with our group focused on the optimization of ring 6 using optical simulations. Mechanically, the rings are assembled using 28 segments in the beam's azimuth, and a single-segment assembly is being constructed and tested in a cosmic stand. In this talk, I will discuss the ring 6 design and prototype performance as well as results from the multiple-ring segment assembly tests. |
Friday, December 1, 2023 11:00AM - 11:15AM |
L11.00009: Test beam facility for the MOLLER and the P2 Experiment Sebastian Baunack, Boris Gläser, Rahima Krini, Frank Maas, Tobias Rimke, Tobias Rimke, Malte Wilfert The MOLLER and the P2 experiment aim to measure the weak mixing angle at small momentum transfer in Moller scattering and elastic Electron Proton scattering respectively. The target accuracy is comparable to the most accurate measurements at the Z-pole. This comprises a sensitive test of the Standard Model. Deviations of the measurement results from the Standard Model prediction can point to new physics beyond the Standard Model, and the sensitivities for new physics of MOLLER and P2 are complementary up to a mass scale of about 50 TeV. Both experiments work at very high (order 100GHz) scattered electron rates requiring largely improved analogue detection techniques. |
Friday, December 1, 2023 11:15AM - 11:30AM |
L11.00010: Neutrino Energy Spectrum and Tensor Current Limit from Boron-8 Beta Decay Brenden R Longfellow, Aaron T Gallant, Grigor H Sargsyan, Mary T Burkey, Tsviki Y Hirsh, Guy Savard, Nicholas Scielzo, Louis Varriano, Maxime Brodeur, Daniel Burdette, Jason A Clark, Daniel Lascar, Kristina D Launey, Peter Mueller, Dwaipayan Ray, Kumar S Sharma, Adrian A Valverde, Gemma L Wilson, Xinliang Yan The high-energy neutrinos observed in solar neutrino astrophysics experiments on Earth predominately originate from 8B beta decay in the Sun. These experiments require the 8B neutrino energy spectrum to be known with high accuracy and precision. Furthermore, 8B beta decay has a large Q value and the daughter 8Be breaks up into two alpha particles making the system particularly sensitive to beyond the standard model physics. Results on both topics from a high-statistics experiment performed at Argonne National Laboratory using the Beta-decay Paul Trap (BPT) will be presented. The energies of the alpha and beta particles were precisely measured with four 32x32 double-sided silicon strip detectors surrounding the BPT. This allowed the unoscillated 8B neutrino energy spectrum, an important input for solar neutrino astrophysics, to be reconstructed. In addition, the measurements were compared with high-fidelity simulations of the decay to set stringent limits on a possible tensor current component to the electroweak interaction. |
Friday, December 1, 2023 11:30AM - 11:45AM |
L11.00011: Unraveling New Physics with Double Beta Decays and Beyond Lukas Graf The quest for neutrinoless double beta decay (0νββ) represents a prominent probe of physics beyond the Standard Model. The new particle physics underlying any potential lepton-number-violating signal can be parametrized within the framework of effective field theory in terms of a set of higher-dimensional operators triggering a variety of distinct 0νββ mechanisms. While it seems to be challenging to unravel the dominant contribution from the observation of this rare nuclear process itself, the (non-)conservation of lepton number can be also tested in a variety of other experiments. We will discuss the phenomenological consequences of double beta decay searches, the limitations and the complementary probes of lepton number violation. |
Friday, December 1, 2023 11:45AM - 12:00PM |
L11.00012: Beta decay beyond the Standard Model in SMEFT Maria Dawid Standard Model Effective Field Theory (SMEFT) provides a model-independent framework for exploring physics beyond the Standard Model. The new physics effects are represented by operators with canonical dimensions D > 4 added to the SM Lagrangian. In this framework, corresponding Wilson coefficients are free parameters that must be determined from experimental data. In this work, we employ a one-loop renormalization-group (RG) improved perturbation theory to constrain relevant dimension-six Wilson coefficients from beta decay. Running the parameters from 5 TeV down to the electroweak scale, we investigate the operator mixing effects of the RG Equations, which introduce new parameters relevant to the beta decay at one loop. Due to the high precision of both experiments and the theory, we received results improving the bounds obtained from other processes at the tree level. In particular, we find a bound for the Wilson coefficient of the four-fermion operator involving light and top quarks to be 5×10-3 which is an order of magnitude better than the result from the top pair production process. |
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