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DOE OSTI2021

Commissioning the DIRC Detector and Searching for Axion-like Particles at GlueX

This thesis centers around problems in the study of the strong nuclear force. The GlueX DIRC, a Cherenkov radiation-based detector, was proposed to upgrade the particle identification capability of the GlueX experiment, which aims to perform quantitative tests of Quantum Chromodynamics in the nonperturbative regime by searching for and studying hybrid mesons. This thesis describes the construction, commissioning, reconstruction, and calibration of the GlueX DIRC detector. Originally proposed to solve the strong CP problem, axions and axion-like particles are hypothetical pseudoscalar particles found in many proposed extensions to the Standard Model of particle physics. This thesis presents a search for photoproduction of axion-like particles using data in photon-proton interactions collected by the GlueX experiment at Jefferson Laboratory in the $\gamma\gamma$ and $\pi^+\pi^-\pi^0$ final states of the axion-like particles. In addition, the Monte Carlo modeling of the strong interaction at low energies leads to challenges known as the event generator tuning problem. This thesis presents a novel approach to the Monte Carlo event generator tuning problem using Bayesian optimization.

Yang, Yunjie↗

DOE OSTI2021

Partial Wave Analysis of Meson Resonances That Decay K*K¯ Using Data from the GlueX Experiment

The GlueX experiment housed in Hall D of the Thomas Jefferson National Laboratory was created to map the light meson spectrum in order to contribute to the Standard Model of particle physics by strengthening our understanding of the strong interaction. GlueX is a medium-energy photoproduction experiment that utilizes a linearly polarized photon beam to create hadronic forms of matter.

Cole, Sebastian↗

DOE OSTI2022

A New Charged Lepton Flavor Violation Program at Fermilab

The muon has played a central role in establishing the Standard Model of particle physics, and continues to provide valuable information about the nature of new physics. A new complex at Fermilab, the Advanced Muon Facility, would provide the world's most intense positive and negative muon beams by exploiting the full potential of PIP-II and the Booster upgrade. This facility would enable a broad muon physics program, including studies of charged lepton flavor violation, muonium-antimuonium transitions, a storage ring muon EDM experiment, and muon spin rotation experiments. This document describes a staged realization of this complex, together with a series of next-generation experiments to search for charged lepton flavor violation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2025

Neutrino-Nucleus Scattering Cross Sections at Medium Energies

The weak interactions of neutrinos with other Standard Model particles are well described within the Standard Model of particle physics. However, modern accelerator-based neutrino experiments employ nuclei as targets, where neutrinos interact with bound nucleons, turning a seemingly simple electroweak process into a complex many-body problem in nuclear physics. At the time of writing this Encyclopedia of Particle Physics chapter, neutrino-nucleus interactions remain one of the leading sources of systematic uncertainty in accelerator-based neutrino oscillation measurements. This chapter provides a pedagogical overview of neutrino interactions with nuclei in the medium-energy regime, spanning a few hundred MeV to several GeV. It introduces the fundamental electroweak formalism, outlines the dominant interaction mechanisms - including quasielastic scattering, resonance production, and deep inelastic scattering - and discusses how nuclear effects such as Fermi motion, nucleon-nucleon correlations, meson-exchange currents, and final-state interactions modify observable cross sections. The chapter also presents a brief survey of the foundational and most widely used theoretical models for neutrino-nucleus cross sections, together with an overview of current and upcoming accelerator-based neutrino oscillation experiments that are shaping the field. Rather than targeting experts, this chapter serves as a primer for advanced undergraduates, graduate students, and early-career researchers entering the field. It provides a concise foundation for understanding neutrino-nucleus scattering, its relevance to oscillation experiments, and its broader connections to both particle and nuclear physics.

Pandey, Vishvas [Fermilab] (ORCID:0000000230827987↗

DOE OSTI2026

US Participation in the Higgs Discovery

On July 4, 2012, scientists at CERN announced the discovery of an essential part of the Standard Model of particle physics: the Higgs boson. The search for the Higgs at experiments at the Large Hadron Collider was an international effort involving thousands of people, with physicists and engineers from US institutions playing a significant role throughout.

Fermilab, Fermilab↗

DOE OSTI2019

Search for the Higgs and Physics Beyond the Standard Model with the CMS Electromagnetic Calorimeter

The Compact Muon Solenoid (CMS) Experiment is a general purpose particle detector experiment at the Large Hadron Collider (LHC) at the European Laboratory for Nuclear Research (CERN). The LHC is the world’s highest energy particle collider, providing proton-proton collisions up to a center-of-mass energy of 13 TeV. The primary aim of the LHC and the CMS Experiment is to discover new physics at this high energy frontier. In 2012, the discovery of the Higgs boson at the LHC marked a crucial milestone in the Standard Model (SM) of particle physics and ushered in the beginning of a new era of exploration at the high energy frontier. Since this discovery, two key areas of study were the characterization of the new particle to confirm that it is, indeed, the predicted SM Higgs boson and also the examination of possible deviations from the SM that may hint at new physics. As a member of the CMS collaboration, the main interest of PI Orimoto has been the study of electromagnetic objects (electrons and photons) as a critical ingredient in the characterization of the Higgs boson, and as a window into physics beyond-the-SM (BSM). To this end, the Orimoto group has led numerous physics analyses ranging from SM Higgs boson studies, searches for exotic production and decay of the Higgs boson, as well as searches for supersymmetric particles. Moreover, the Orimoto group has made significant contributions to the CMS electromagnetic calorimeter (ECAL), the sub-detector responsible for the precise measurement of the energies of electrons and photons. The Orimoto group’s contributions have been recognized with many leadership roles and high profile conference presentations. This report outlines the group’s products and accomplishments from the award period (June 2013 through July 2018).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2020

NLOX, a one-loop provider for Standard Model processes

NLOX is a computer program for calculations in high-energy particle physics. It provides fully renormalized scattering matrix elements in the Standard Model of particle physics, up to one-loop accuracy for all possible coupling-power combinations in the strong and electroweak couplings, and for processes with up to six external particles.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2021

The Search for μ+ → e+γ with 10–14 Sensitivity: The Upgrade of the MEG Experiment

The MEG experiment took data at the Paul Scherrer Institute in the years 2009–2013 to test the violation of the lepton flavor conservation law, which originates from an accidental symmetry that the Standard Model of elementary particle physics has, and published the most stringent limit on the charged lepton flavor violating decay μ+→e+γ: BR(μ+→e+γ) <4.2×10−13 at 90% confidence level. The MEG detector has been upgraded in order to reach a sensitivity of 6×10−14. The basic principle of MEG II is to achieve the highest possible sensitivity using the full muon beam intensity at the Paul Scherrer Institute (7×107 muons/s) with an upgraded detector. The main improvements are better rate capability of all sub-detectors and improved resolutions while keeping the same detector concept. In this paper, we present the current status of the preparation, integration and commissioning of the MEG II detector in the recent engineering runs.

physics beyond the Standard Model↗

DOE OSTI2017

Cosmological constraints on interacting light particles

Cosmological observations are becoming increasingly sensitive to the effects of light particles in the form of dark radiation (DR) at the time of recombination. The conventional observable of effective neutrino number, N {sub eff}, is insufficient for probing generic, interacting models of DR. In this work, we perform likelihood analyses which allow both free-streaming effective neutrinos (parametrized by N {sub eff}) and interacting effective neutrinos (parametrized by N {sub fld}). We motivate an alternative parametrization of DR in terms of N {sub tot} (total effective number of neutrinos) and f {sub fs} (the fraction of effective neutrinos which are free-streaming), which is less degenerate than using N {sub eff} and N {sub fld}. Using the Planck 2015 likelihoods in conjunction with measurements of baryon acoustic oscillations (BAO), we find constraints on the total amount of beyond the Standard Model effective neutrinos (both free-streaming and interacting) of Δ N {sub tot} < 0.39 at 2σ. In addition, we consider the possibility that this scenario alleviates the tensions between early-time and late-time cosmological observations, in particular the measurements of σ{sub 8} (the amplitude of matter power fluctuations at 8 h {sup −1} Mpc), finding a mild preference for interactions among light species. We further forecast the sensitivities of a variety of future experiments, including Advanced ACTPol (a representative CMB Stage-III experiment), CMB Stage-IV, and the Euclid satellite. This study is relevant for probing non-standard neutrino physics as well as a wide variety of new particle physics models beyond the Standard Model that involve dark radiation.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2024

Probing New Physics with Tau Leptons using the CMS Detector

The Standard Model (SM) of particle physics is a thoroughly well-tested theory of all electroweak scale phenomena to date—the most recent test being the discovery of the long-predicted Higgs boson. However, there is much evidence to suggest that it is incomplete. On the formal side, the mass of the Higgs particle itself is perplexingly small, while the largest theoretical energy scale of the SM is 17 orders of magnitude larger, a puzzle known as the hierarchy problem. On the experimental side, among other things, the SM lacks a candidate for dark matter, which is now known to play an indispensable role in astrophysical large scale structure formation. Many theories that address the fundamental puzzles of the SM predict the existence of multiple Higgs bosons, including a very light boson that couples preferentially to third-generation fermions. Observation of this new light boson, either directly produced or in the decay of the recently discovered SM Higgs, would provide an unmistakable sign of new dynamics in nature. The research supported by this award used data collected by the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) to explore boosted di-tau signatures of a new light boson as a tool in the quest to understand the shortcomings of the SM. With a proton-proton collision energy of 13 trillion electron-volts (TeV) and peak instantaneous proton luminosity of over 10^34 collisions per square centimeter per second (cm –2 s –1 ), the LHC is the only facility in the world that could enable this line of research. The research sought to address the hierarchy problem and other shortcomings of the SM through a mixture of LHC data analysis, maintenance of the CMS detector to ensure high quality data, and contributions to the Phase 2 upgrade detector for the upcoming High Luminosity phase of the LHC (HL-LHC).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2019

Review on Composite Higgs Models

Composite Higgs Models explore the possibility that the Higgs boson is an excitation of a new strongly interacting sector giving rise to electro-weak symmetry breaking. After describing how this new sector can be embedded into the Standard Model of elementary particle physics meeting experimental constraints, I will review efforts by the community to explore the physics of the new strong interaction using methods of lattice field theory. Challenges in understanding the numerical results are discussed and an outlook is given on possible future directions allowing to confirm or reject the composite Higgs hypothesis.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2016

Enhancing the Higgs associated production with a top quark pair

It is pointed out that in a wide class of models reminiscent of type-II Two-Higgs-Doublet Models (2HDM) the signal of the Higgs produced in association with a top-antitop quark pair ($tth$) and decaying into gauge bosons can be significantly larger than the Standard Model (SM) prediction without violating any experimental constraints. The crucial feature of these models is enhanced (suppressed) Higgs coupling to top (bottom) quarks and existence of light colored particles that give negative contribution to the effective Higgs coupling to gluons resulting in the gluon fusion rates in the gauge boson decay channels close to SM predictions. We demonstrate this mechanism in NMSSM with light stops and show that $tth$ signal in the W W decay channel can be two times larger than the SM prediction, as suggested by the excesses observed by ATLAS and CMS, provided that the Higgs-singlet superpotential coupling $λ ≳$ 0.8 and the MSSM-like Higgs boson masses are in the range of 160 to 300 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Discovering Elusive Dynamics Across Frontiers (Final Technical Report)

Profound puzzles, such as the nature of dark matter, the origins of the electroweak scale, the mechanism behind the small neutrino mass, and the strong CP problem, suggested new physics beyond the Standard Model and drove the particle physics program in search of the associated new particles. Despite extensive searches, conventional realizations of new physics have not yet provided conclusive evidence. This raised the serious possibility that new dynamics might be more elusive, perhaps due to a richer gauge and matter structure than previously considered. Notably, the existence of dark matter and advancements in understanding the naturalness problem urged exploration into sectors with complex gauge and matter structures. Through experiments like the LHC, DUNE, and small-scale experiments, the robust US HEP program played a critical role in pursuing these well-motivated but under-explored scenarios for new physics. I explored these physics opportunities in depth, focusing on novel searches and significant improvements in parameter space coverage. The elusive dynamics revealed rich information about the underlying theory and were essential in identifying observable opportunities. Understanding the observable consequences required a deep comprehension of the theory, which I also developed. The proposal included essential components aimed at coherently increasing our knowledge in well-motivated elusive dynamics models. Through research on high-quality axions, composite neutrinos, the Higgs boson as a portal to hidden strong dynamics, and new scalar potentials to generate alternative electroweak phase transitions, I focused on identifying new signatures and parameter regions in plausible elusive dynamics models. The exploration emphasized generic possibilities motivated by broad classes of elusive dynamics models. These signatures were not effectively probed previously due to various challenges such as triggering, background suppression, or experimental design. My research involved close interaction with experimental colleagues to overcome these difficulties, leveraging new theoretical and experimental possibilities. These efforts included identifying new observables such as timing information and substructure in calorimetries, new multiple-hit techniques, new scattering events, and new resonance searches in liquid argon detectors. This work created a positive feedback loop: theory and experimental work inspired each other, revealing new exciting opportunities that supported both programs.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2016

Landscape of Future Accelerators at the Energy and Intensity Frontier

An overview is provided of the currently envisaged landscape of charged particle accelerators at the energy and intensity frontiers to explore particle physics beyond the standard model via 1-100 TeV-scale lepton and hadron colliders and multi-Megawatt proton accelerators for short- and long- baseline neutrino experiments. The particle beam physics, associated technological challenges and progress to date for these accelerator facilities (LHC, HL-LHC, future 100 TeV p-p colliders, Tev-scale linear and circular electron-positron colliders, high intensity proton accelerator complex PIP-II for DUNE and future upgrade to PIP-III) are outlined. Potential and prospects for advanced “nonlinear dynamic techniques” at the multi-MW level intensity frontier and advanced “plasma- wakefield-based techniques” at the TeV-scale energy frontier and are also described.

43 PARTICLE ACCELERATORS↗

DOE OSTI2014

FSU High Energy Physics

The High Energy Physics group at Florida State University (FSU), which was established in 1958, is engaged in the study of the fundamental constituents of matter and the laws by which they interact. The group comprises theoretical and experimental physicists, who sometimes collaborate on projects of mutual interest. The report highlights the main recent achievements of the group. Significant, recent, achievements of the group’s theoretical physicists include progress in making precise predictions in the theory of the Higgs boson and its associated processes, and in the theoretical understanding of mathematical quantities called parton distribution functions that are related to the structure of composite particles such as the proton. These functions are needed to compare data from particle collisions, such as the proton-proton collisions at the CERN Large Hadron Collider (LHC), with theoretical predictions. The report also describes the progress in providing analogous functions for heavy nuclei, which find application in neutrino physics. The report highlights progress in understanding quantum field theory on a lattice of points in space and time (an area of study called lattice field theory), the progress in constructing several theories of potential new physics that can be tested at the LHC, and interesting new ideas in the theory of the inflationary expansion of the very early universe. The focus of the experimental physicists is the Compact Muon Solenoid (CMS) experiment at CERN. The report, however, also includes results from the D0 experiment at Fermilab to which the group made numerous contributions over a period of many years. The experimental group is particularly interested in looking for new physics at the LHC that may provide the necessary insight to extend the standard model (SM) of particle physics. Indeed, the search for new physics is the primary task of contemporary particle physics, one motivated by the need to explain certain facts, such as the non-zero neutrino masses or the overwhelming astrophysical evidence for an invisible form of matter, called dark matter, that has had a marked effect on the evolution of structure in the universe. The report highlights the main, recent, experimental achievements of the experimental group, which include the investigation of properties of the W and Z bosons; the search for new heavy stable charged particles and the search for a proposed property of nature called supersymmetry in proton-proton collisions that yield high energy photons. In addition, we report a few results from a more general search for supersymmetry at the LHC, initiated by the group. The report also highlights the group's significant contributions, both theoretical and experimental, to the 2012 discovery of the Higgs boson and the measurement of its properties.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2016

Neutrons and Fundamental Symmetries

The research supported by this project addressed fundamental open physics questions via experiments with subatomic particles. In particular, neutrons constitute an especially ideal “laboratory” for fundamental physics tests, as their sensitivities to the four known forces of nature permit a broad range of tests of the so-called “Standard Model”, our current best physics model for the interactions of subatomic particles. Although the Standard Model has been a triumphant success for physics, it does not provide satisfactory answers to some of the most fundamental open questions in physics, such as: are there additional forces of nature beyond the gravitational, electromagnetic, weak nuclear, and strong nuclear forces?, or why does our universe consist of more matter than anti-matter? This project also contributed significantly to the training of the next generation of scientists, of considerable value to the public. Young scientists, ranging from undergraduate students to graduate students to post-doctoral researchers, made significant contributions to the work carried out under this project.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2018

Muon Anomalous Precession Frequency Measurement Using Lead Fluoride Calorimeters in the Muon g-2 Experiment

aThe Standard Model (SM) of particle physics has been strikingly successful in explaining a wide range of physical phenomena and almost all experimental results. One of the most significant discrepancies at present is the anomalous magnetic moment $a_\mu$=(g−2)/2 of the muon, which was measured by the E821 collaboration at BNL in 2004 to be more than three-standard-deviation greater than the SM prediction. Various models beyond SM physics have been proposed to explain this discrepancy, but the key to resolving this tension remains a more precise measurement of $a_{\mu}$. The Muon g-2 collaboration at Fermilab aims to measure $a_{\mu}$ with a precision goal of 140 parts per billion, a fourfold improvement over BNL's result. If the central values of the experimental result and the theoretical prediction remain unchanged, the discrepancy will exceed seven standard deviations which a clear indication of physics beyond SM. In this poster, preliminary results from th e ongoing physics data taking will be presented, especially on the measurement of the muon anomalous precession frequency using lead fluoride calorimeters. Energy calibration and timing alignment procedures of calorimeter channels will also be described, and their impact on high-level analyses will be discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Exploring the Higgs and Hidden Sectors (Final Report for SC0023093)

This grant partially supported the research of the PI, Stefania Gori, and of the postdoc, Jeff Dror, at the University of California, Santa Cruz. The supported research focused on particle physics beyond the Standard Model (SM) and, more specifically, on addressing the nature of Dark Matter (DM) and the origin of flavor.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗