Berkeley Undergraduate Researchers

Catherine Welch, current INT UW/N3AS student

Publication on arXiv.org
by Mia Kumamoto and Catherine Welch:
Effects of Landau quantization on neutrino emission and absorption →

Some neutron stars known as magnetars possess very strong magnetic fields, with surface fields as large as and internal fields that are possibly stronger. Recent observations of the radio pulsar GLEAM-X J1627 suggest it may have a surface field as strong as . In the presence of a strong magnetic field, the energy levels of electrons and protons are quantized and the Direct Urca process allows neutron stars to cool rapidly, even at low density. For the case of magnetic fields , we find features in the emissivity due to energy quantization that are not captured by the frequently employed quasiclassical approximation… read more

Danial Baradaran, current N3AS student

Publication accepted by Physical Review D
by Danial Baradaran, Boryana Hadzhiyska, Martin J. White, and Noah Sailer:
Predicting the 21 cm field with a Hybrid Effective Field Theory approach →

A detection of the 21 cm signal can provide a unique window of opportunity for uncovering complex astrophysical phenomena at the epoch of reionization and placing constraints on cosmology at high redshifts, which are usually elusive to large-scale structure surveys. In this work, we provide a theoretical model based on a quadratic bias expansion capable of recovering the 21 cm power spectrum with high accuracy sufficient for upcoming ground-based radio interferometer experiments. In particular, we develop a hybrid effective field theory (HEFT) model in redshift space that leverages the accuracy of N-body simulations with the predictive power of analytical bias expansion models, and test it against the Thesan suite of radiative transfer hydrodynamical simulations… read more

Danial Baradaran

Santiago Rodriguez, Former student;
REU Coordinator, Space Sciences Laboratory

Publication on arXiv.org
by Lucas Johns and Santiago Rodriguez:
Collisional flavor pendula and neutrino quantum thermodynamics →

Neutrino flavor oscillation occurs because neutrinos emitted in a certain flavor are composed of a superposition of different neutrino mass states. In a dense enough environment, neutrino self-interactions synchronize flavor on large scales. In the two-flavor approximation, the resulting dynamics show similar behavior to the classical spinning top and inverted pendulum under some conditions. We explore the neutrino flavor pendulum with the addition of charged-current interactions and absorption/emission processes. In addition, investigating their effects in densities and time scales relevant to the isotropic and monochromatic emission of neutrinos from core-collapse supernovae, similar to neutrino the bulb model. We are able to identify the synchronized and bipolar modes of oscillation and constrain the polarization pendulum to a sphere and a circle in flavor space.

In 2023, Santiago has presented this research at the American Physical Society Far West Section, in San Diego.

Malika Golshan, Former student;
SULI intern at LBL

Publication on arXiv.org
by Malika Golshian and Adrian Bayer:
Massive νs through the CNN lens: interpreting the field-level neutrino mass information in weak lensing →

Neutrinos, once thought to be massless according to the standard model, have proven otherwise due to the fascinating observation of neutrino flavor oscillations. In our research project, we take a unique approach by harnessing the power of machine learning to address a crucial question: Can computers aid in distinguishing between mass-bearing and massless neutrinos? By leveraging Convolutional Neural Networks (CNNs) on simulated weak lensing maps, our goal is to achieve a more accurate measurement of neutrino mass using cosmological methods.

I am deeply grateful to both my mentors. Vanessa, my initial mentor, provided me with a solid foundation and inspiration for this project. Adrian then became my mentor while transitioning to his postdoctoral position at Princeton. His unwavering dedication and expertise guided me through the intricacies of data analysis.

Malika Golshan

Henry Purcell, Former student;
Intern, NASA Ames Research Center

Publication accepted by Physical Review D (May 2024)
by Henry Purcell, Sherwood Richers, Amol V. Patwardhan, Francois Foucart:
Three-flavor, Full Momentum Space Neutrino Spin Oscillations in Neutron Star Mergers →

In the presence of anisotropic neutrino and antineutrino fluxes, the quantum kinetic equations drive coherent oscillations in neutrino helicity, frequently referred to as spin oscillations. These oscillations depend directly on the absolute mass scale and Majorana phase, but are usually too transient to produce important effects. In this paper we present a full momentum-space analysis of Majorana neutrino spin oscillations in a snapshot of a three-dimensional neutron star merger simulation. We find an interesting angular dependence that allows for that resonant and adiabatic oscillations to occur along specific directions in a large volume of the merger remnant… read more

Graduated 2023, currently training in Los Alamos, working with the DUNE team

Discovering the origin of neutrino’s mass and their oscillation parameters could answer the matter antimatter asymmetry in our universe, and allow us to better understand astrophysics phenomena. Currently, multiple flagship experiments exploring neutrinos are underway, and to have full confidence in their results, accurate and precise neutrino nucleus cross sections are required. My project is to analyze data from lattice QCD calculations to determine one of these cross sections.