The Particle Physics Community Planning Exercise, also known as “Snowmass” is organized every ~10 years by the American Physical Society (APS) Division of Particles and Fields (DPF). It is meant to “identify and document a scientific vision for the future of particle physics in the U.S. and its international partners”.

I focused on contributions to the Neutrino Frontier (NF) and the Community Engagement Frontier (CEF).

Neutrino Frontier (NF)

Toward CUPID-1T

Current experiments to search for broken lepton-number symmetry through the observation of neutrinoless double-beta decay (0$\nu\beta\beta$) provide the most stringent limits on the Majorana nature of neutrinos and the effective Majorana neutrino mass (m_$\beta\beta$). The next-generation experiments will focus on the sensitivity to the 0$\nu\beta\beta$ half-life of O(10²⁷–10²⁸ years) and m_$\beta\beta$$\le$15 meV, which would provide complete coverage of the so-called Inverted Ordering region of the neutrino mass parameter space. By taking advantage of recent technological breakthroughs, new, future calorimetric experiments at the 1-ton scale can increase the sensitivity by at least another order of magnitude, exploring the large fraction of the parameter space that corresponds to the Normal neutrino mass ordering. In case of a discovery, such experiments could provide important insights toward a new understanding of the mechanism of 0$\nu\beta\beta$. We present here a series of projects underway that will provide advancements in background reduction, cryogenic readout, and physics searches beyond 0$\nu\beta\beta$, all moving toward the next-to-next generation CUPID-1T detector.

Community Engagement Frontier (CEF)

Diversity, Equity, and Inclusion in Particle Physics

To achieve the highest level of intellectual excellence calls for the greatest extent of diversity. However, due to the unjust institutional and societal barriers, the field of particle physics remains as one of the least diverse fields, severely limiting the potential of our scientific achievements. In order for the US Particle Physics Community, including the accelerator science and engineering fields, to remain at the forefront of global scientific leadership, it is imperative for our community to act urgently and diligently to improve the status quo of diversity, equity, inclusion, and accessibility (DEIA). This report summarizes the community contributions and recommendations within the Diversity and Inclusion Topical Group of the Community Engagement Frontier (CEF3) at the Snowmass 2021.

Climate of the Field: Snowmass 2021

How are formal policies put in place to create an inclusive, equitable, safe environment? How do these differ between different communities of practice (institutions, labs, collaborations, working groups)? What policies towards a more equitable community are working? For those that aren’t working, what external support is needed in order to make them more effective? We present a discussion of the current climate of the field in high energy particle physics and astrophysics (HEPA), as well as current efforts toward making the community a more diverse, inclusive, and equitable environment. We also present issues facing both institutions and HEPA collaborations, with a set of interviews with a selection of HEPA collaboration DEI leaders. We encourage the HEPA community and the institutions & agencies that support it to think critically about the prioritization of people in HEPA over the coming decade, and what resources and policies need to be in place in order to protect and elevate minoritized populations within the HEPA community.

Transforming U.S. Particle Physics Education: A Snowmass 2021 Study

The pursuit of knowledge in particle physics requires constant learning. As new tools become available, new theories are developed, and physicists search for new answers with ever-evolving methods. However, it is the case that formal educational systems serve as the primary training grounds for particle physicists. Graduate school (and undergraduate school to a lesser extent) is where researchers learn most of the technical skills required for research, develop scientific problem-solving abilities, learn how to establish themselves in their field, and begin developing their career. It is unfortunate, then, that the skills gained by physicists during their formal education are often mismatched with the skills actually required for a successful career in physics. We performed a survey of the U.S. particle physics community to determine the missing elements of graduate and undergraduate education and to gauge how to bridge these gaps. In this contributed paper, part of the 2021-22 Snowmass Community Planning Exercise, we report the results of this survey. We also recommend several specific community actions to improve the quality of particle physics education; the “community” here refers to physics departments, national labs, professional societies, funding agencies, and individual physicists.