Session LA: Award Session

Mentoring Award: Can a photophobic vector boson explain the ATOMKI anomaly?

In 2016, the ATOMKI collaboration announced the  observation an unexpected enhancement of the  electron-positron pair production signal in one of the nuclear transitions induced by an incident proton beam on a 7Li target. This finding led to many beyond-standard-model physics explanations. One popular theory is that the anomaly is caused by the creation of a protophobic vector boson (X) with a mass around 17 MeV  the nuclear transition. We studied [2] this hypothesis by deriving an isospin relation between photon and X couplings to nucleons. This allowed us to find simple relations between protophobic X-production cross sections and those for measured photon production. The net result is that X production can be  dominated by direct transitions induced by and (transverse and longitudinal electric dipoles) and (charge dipole) without going through any nuclear resonance (i.e. Bremsstrahlung radiation) with a smooth energy dependence that occurs for all proton beam energies above threshold. This work caused the ATOMKI [3] and other collaborations to search for the production of X particles in non-resonant transitions. An update will be provided.

1. A.J. Krasznahorkay, et al.,  Phys. Rev. Lett. 116, 042501 (2016)]

2. X. Zhang and G. A. Miller, Phys. Lett. B813, 136061 (2021)

3. N. J. Sas et al., arXiv:2205.07744 [nucl-ex]

    

Freedman Award: Laser spectroscopy studies of radioactive atoms and molecules

Atoms and molecules containing radioactive nuclei, with extreme proton-to-neutron ratios, can be created to study particular nuclear phenomena. Precision laser spectroscopy measurements of these systems can offer unique insights into the properties of atomic nuclei, nuclear matter, and the fundamental particles and forces of nature. In this talk, I will present recent results and perspectives from laser spectroscopy experiments of these exotic species.   

Dissertation Award in Nuclear Physics Talk: The equation of state of dense nuclear matter from heavy-ion collisions

The equation of state (EOS) of dense nuclear matter has been the center of numerous research efforts over the years. Studies of giant monopole resonances in heavy nuclei indicate that the EOS is soft around the saturation density of nuclear matter. On the other hand, recent analyses of neutron star data strongly suggest that in the cores of neutron stars, where densities may reach several times that of normal nuclear matter, the EOS becomes very stiff — so stiff, in fact, that the speed of sound squared may substantially exceed the conformal limit of 1/3.  

In this talk, I will discuss my thesis work in which I proposed a novel way of using higher moments of the baryon number distribution, measured in experiments, to infer the speed of sound in dense nuclear matter created in low-energy heavy-ion collisions. I will also highlight the need for state-of-the-art hadronic transport simulations to draw meaningful conclusions from the experimental data. I will then present the framework I developed to enable comprehensive studies of the influence of the dense nuclear matter EOS on experimental observables, and its potential for playing an important role in uncovering the phase diagram of dense QCD matter.   

Dissertation Award in Nuclear Physics Talk: Building Efficient and Interpretable AI for Neutrinoless Double-Beta Decay Searches

The discovery of Majorana neutrinos would fundamentally revise our understanding of physics and the cosmos. Currently, the most effective experimental probe of the Majorana neutrinos is neutrinoless double-beta decay(0??ββ). Meanwhile, the explosive growth of artificial intelligence over the last decade has brought new opportunities to 0??ββ experiments. Efficient and interpretable AI algorithms could break down significant technological barriers and, in turn, deliver the world's most sensitive search for 0??ββ. This talk will discuss one such algorithm--KamNet, which plays a pivotal role in the new result of the KamLAND-Zen experiment. With the help of KamNet, KamLAND-Zen provides a limit that reaches below 50 meV for the first time and is the first search for 0νββ in the inverted mass ordering region. Looking further, the next-generation 0??ββ experiment LEGEND has created the Germanium Machine Learning group to pursue an efficient and interpretable AI analysis chain. As the odyssey continues, AI will enlighten the bright future of 0νββ and fundamental symmetries in general.