LBNL Physics Division Research Progress Meetings

Speaker: Alex Wang (UCSC) - Title: Searching for di-Higgs production with the bbγγ final state: early Run 3 and beyond
2025-07-24 16:00 - 17:00 UTC
Research Progress Meeting
Date: July 24, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Alex Wang (UCSC)
Title: Searching for di-Higgs production with the bbγγ final state: early Run 3 and beyond
Abstract: Since the discovery of the Higgs boson by the ATLAS and CMS experiments in 2012, many of its properties have been constrained by precision measurements using LHC Run 2 data. One notable exception is the Higgs self coupling lambda, which modifies the shape of the Higgs potential and, in the Standard Model, is completely determined by the Higgs mass and vacuum expectation value. A value of lambda different from the Standard Model prediction could have profound implications for particle physics and cosmology. The simultaneous production of two Higgs bosons (di-Higgs), is the most accessible way to study this coupling at the LHC but presents experimental challenges due to its low production cross-section, about three orders of magnitude smaller than that of single Higgs.
In this talk, I will present the latest ATLAS search for di-Higgs production with the bbγγ final state, in which one Higgs decays into a pair of b-quarks and the other decays into a pair of photons. This is one of the most experimentally powerful channels due to the high H->bb branching ratio and the excellent ATLAS photon resolution. With the inclusion of the Run 2 (2015 – 2018) and early Run 3 (2022 – 2024) LHC datasets, these new results constitute both the first ATLAS result using over 300ifb of data and also the world’s best single-channel di-Higgs constraints to-date. Finally, I will discuss the latest prospects for the High Luminosity LHC, which is expected to increase the dataset by over a factor of 10 and bring us within observation of di-Higgs production.
https://lbnl.zoom.us/j/98854322464?pwd=[REDACTED]
Meeting ID: 988 5432 2464

Passcode: [REDACTED]

Speaker: Regina Demina (U of Rochester) - Title: How Quantum Are Elementary Particles? Exploring Entanglement and the Quest for Toponium
2025-07-15 16:00 - 17:00
Research Progress Meeting
Date: July 15, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Regina Demina (University of Rochester)
Title: How Quantum Are Elementary Particles? Exploring Entanglement and the Quest for Toponium

Abstract: While quantum mechanics underpins particle physics, truly quantum effects are surprisingly difficult to establish in high-energy interactions. A rare exception comes from recent observations of quantum entanglement in top–antitop quark pairs by the ATLAS and CMS experiments. In certain regions of phase space, these particles appear to lie outside the causality cone, making the result even more intriguing. In this talk, I will review the details of these groundbreaking measurements, their implications, and potential criticisms. Some deviation in the observed level of correlation between top and antitop quarks resulted in an exciting discovery of toponium, a bound state of top and antitop quarks observed by CMS. Recently confirmed by Atlas, toponium is the heaviest known composite particle, with a mass of 343 GeV—surpassing even the heaviest nucleus, Oganesson, at 279 GeV.
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Meeting ID: 956 7989 2182
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Speaker: Michael Reh (Boulder) - Title: Improving the Super-Kamiokande Analysis in the T2K Experiment
2025-07-10 16:00 - 17:00
Research Progress Meeting
Date: July 10, 2025
Time: 4:00- 5:00 pm
Location: This is a virtual event. Please see zoom link below.
Speaker: Michael Reh (Boulder)
Title: Improving the Super-Kamiokande Analysis in the T2K Experiment
Abstract: The Tokai-to-Kamioka (T2K) Experiment is a long baseline neutrino oscillation experiment located in Japan. T2K searches for muon neutrino disappearance and electron neutrino appearance oscillations at its far detector, Super-Kamiokande (SK). When performing the T2K neutrino oscillation analysis, the SK detector performance and reconstruction must be well understood in order to be certain of the number of muon and electron neutrino events observed. The T2K event reconstruction algorithm fiTQun does well to classify simulated electron and muon events in the detector, however differences in reconstruction performance between simulated and real data events can bias the T2K analysis results. In this seminar, the methods for estimating the T2K-SK detector reconstruction uncertainty will be discussed, including significant upgrades that include events with multiple visible particle final states in the T2K-SK analysis for the first time.
https://lbnl.zoom.us/j/98854322464?pwd=[REDACTED]
Meeting ID: 988 5432 2464

Passcode: [REDACTED]

Speaker: Nicole Hartman (Technical University of Munich) - Title: b-tagging unlocks the Higgs Potential — deep learning for jet flavour tagging on ATLAS
2025-07-03 12:00 - 13:00
Research Progress Meeting
Date: July 3, 2025
Time: noon – 1:00 pm [note special time]
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Nicole Hartman (Technical University of Munich)
Title: b-tagging unlocks the Higgs Potential — deep learning for jet flavour tagging on ATLAS
Abstract:
Electroweak symmetry breaking involves a Higgs potential that generates mass for the weak bosons. In the Standard Model, this potential has a quartic form—but this is merely an ansatz that has yet to be experimentally verified. A first experimental probe of the Higgs potential could come from measuring the simultaneous production of two Higgs bosons (“di-Higgs”). This is an exceptionally rare process, expected to require another decade of data collection to discover using current analysis methods. The most probable decay mode of a Higgs boson is into a pair of b-quarks, which in turn produce b-jets in the detector. The channels driving di-Higgs sensitivity therefore all include b-jets in the final state.
Machine learning is transforming many areas of life, and particle physics is no exception. Because of the complexity of jets at the LHC, b-jet classification (or flavour tagging) has become a leading application of deep learning in the field. This seminar presents the state-of-the-art in flavour tagging: a transformer model, the same backbone architecture used in ChatGPT. These modern transformers deliver an impressive factor-of-four improvement in performance compared to earlier b-taggers based on recurrent neural networks. In addition, transformers are more data-efficient, allowing us to benefit from a tenfold increase in training statistics. Importantly, these gains in simulation also translate to actual LHC data.
Transformers are general-purpose architectures that can be integrated at multiple stages of the analysis pipeline. As training datasets continue to grow, we can begin to view jet tagging as a foundation model for LHC physics—one that can be customized or “fine-tuned” for specific physics goals. We conclude by highlighting how an end-to-end optimizable analysis can fine-tune a jet-tagger for an HH physics search, helping to further advance our di-Higgs program and quest to understand the Higgs potential.

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Meeting ID: 988 8101 1162
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Speaker: Marco Bonici (Waterloo) - Title: Taming projection effects in galaxy clustering analysis
2025-07-01 16:00 - 17:00
Research Progress Meeting
Date: July 1, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Marco Bonici (Waterloo)
Title: Taming projection effects in galaxy clustering analysis
Abstract: The analysis of galaxy clustering measurements from surveys like Euclid or DESI is likely to be affected by the so called projection effects, which causes the 1D marginals of the analysis to not contain the bestfit; this is a serious issue which can potentially harm the cosmological interpretation of these analyses. I will outline three complementary strategies to mitigate this bias: (i) simulation-calibrated priors, (ii) a frequentist framework based on profile likelihoods, and (iii) a Bayesian re-parameterisation that isolates degenerate directions. Applied to full shape data, each method reduces the impact of projection effects. I will present the reduction of the projection effects for each technique when applied to DESI data.
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Meeting ID: 956 7989 2182
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Speaker: Bob Hirosky (Virginia) - Title: High resolution calorimetry from the LHC to a future Higgs Factory
2025-06-26 16:00 - 17:00
Research Progress Meeting
Date: June 26, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Bob Hirosky (Virginia)
Title: High resolution calorimetry from the LHC to a future Higgs Factory
Abstract: High Energy Physics experiments employ calorimeters using various technologies for the measurement of high energy particles. This talk will review the detector physics and some challenges of precision measurements with the CMS homogeneous crystal calorimeters and discuss preparations to achieve the physics goals of the High Luminonisty LHC.
Looking forward to a future Higgs Factory I will summarize some of the international planning efforts for new detector concepts, including the CalVision/MaxiCC R&D programs which aim to produce a new, hybrid dual-readout calorimeter to achieve state-of-the-art calorimetric measurements of all final state particles.
https://lbnl.zoom.us/j/98854322464?pwd=[REDACTED]
Meeting ID: 988 5432 2464

Passcode: [REDACTED]

Speaker: Ryan Roberts (LBNL) - Title: Measuring the Top Yukawa Coupling with Graph Neural Networks
2025-06-17 16:00 - 17:00
Research Progress Meeting
Date: June 17, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Ryan Roberts (LBNL)
Title: Measuring the Top Yukawa Coupling with Graph Neural Networks
Abstract: The top Yukawa coupling is a key prediction of the Standard Model and has been relatively inaccessible before Run-2 at the LHC. It has ties to many of the big questions surrounding the SM, including the fermion mass hierarchy, vacuum stability, the hierarchy problem, and the nature of the Higgs sector. Sensitive final states, including top-associated Higgs production and four-top production, have complex signatures which are natural targets for advanced machine learning techniques such as graph neural networks (GNNs). This talk presents the observation of four-top production, achieved with a graph neural network, and subsequent constraints on the Higgs boson’s coupling to top quarks and the total width of the Higgs boson. The interplay between physics objectives and developments in machine learning techniques drives the development of new strategies to maximize the physics output of the LHC program, including the sensitivity of future top Yukawa measurements.

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Meeting ID: 956 7989 2182
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Speaker: Josh Dillon (UC Berkeley) - Title: Recent Progress in 21 cm Cosmology with the Hydrogen Epoch of Reionization Array
2025-05-08 16:00 - 17:00
Research Progress Meeting
Date: May 8, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Josh Dillon (UC Berkeley)
Title: Recent Progress in 21 cm Cosmology with the Hydrogen Epoch of Reionization Array
Abstract: 21 cm cosmology promises a revolutionary new probe of the astrophysics and cosmology of the Cosmic Dawn and the epoch of reionization (EoR). I will discuss our progress with the Hydrogen Epoch of Reionization Array (HERA), an interferometer in South Africa with 350 14-m dishes, purpose-built for 21 cm cosmology. With early HERA data and only a small fraction of its final size and bandwidth, we have set world-leading limits on the 21 cm power spectrum. These results already have important astrophysical implications: they largely rule out “cold reionization” scenarios, provide a lower bound on the X-ray heating of the intergalactic medium, and constrain models of its origin. We are now preparing our first limits from HERA’s new broadband system (5 < z < 25), which should lay the groundwork for future results that realize the instrument’s full potential. In this talk, I will present these limits, their interpretation, and their statistical validation. Finally, I will look forward to the exciting science we can expect in the next few years from HERA, as well as the lessons it holds for future arrays for 21 cm cosmology.
https://lbnl.zoom.us/j/98854322464?pwd=[REDACTED]
Meeting ID: 988 5432 2464

Passcode: [REDACTED]

Speaker: Kevin O'Brien (MIT) - Title: Broadband quantum-limited amplification and near-ultrastrong light-matter coupling with superconducting circuits
2025-05-01 16:00 - 17:00
Research Progress Meeting
Date: May 1, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Kevin O’Brien (MIT)
Title: Broadband quantum-limited amplification and near-ultrastrong light-matter coupling with superconducting circuits
Abstract: Superconducting qubits are one of the leading quantum computing platforms in part due to the nonlinearity of the Josephson junction. High quantum efficiency broadband amplification is a key requirement for high fidelity qubit readout and thus implementing quantum error correction. We illustrate the modeling and design of high quantum efficiency broadband parametric amplifiers using our open source package JosephsonCircuits.jl [1]. These amplifiers are engineered to match the Floquet modes in the amplifier to the eigenmodes of the environment, eliminating a previously ubiquitous noise mechanism in broadband amplifiers [2]. We present the fabrication of such amplifiers using a high-Q qubit fabrication process with state of the art junction critical current uniformity. We detail the characterization of these amplifiers including the highest reported quantum efficiency for a traveling wave parametric amplifier [3] and future directions of on-chip integration and isolation. Finally, we show how qubits with quartic [4] rather than the familiar weakly anharmonic potential enable the first demonstration of near-ultrastrong nonlinear coupling [5] with applications in fast qubit readout [6] and gates.
[1] K. Peng, R. Poore, P. Krantz, D. E. Root, and K. P. O’Brien “X-parameter based design and simulation of Josephson traveling-wave parametric amplifiers for quantum computing applications” IEEE QCE22 (2022)
[2] K. Peng, M. Naghiloo, J. Wang, G. D. Cunningham, Y. Ye, and K. P. O’Brien “Floquet-Mode Traveling-Wave Parametric Amplifiers” PRX Quantum 3, 020306 (2022)
[3] J. Wang*, K. Peng*, G. D. Cunningham, A. Lombo, A. Yen, D. Zaidenberg, W. D. Oliver, K. P. O’Brien “High-Efficiency, Low-Loss Floquet-Mode Traveling-Wave Parametric Amplifier” arxiv 2503.11812 (2025)
[4] Y. Ye, K. Peng, M. Naghiloo, G. Cunningham, K. P. O’Brien “Engineering purely nonlinear coupling between superconducting qubits using a quarton” Physical Review Letters 127 (5), 050502 (2022)
[5] Y. Ye, J. B. Kline, A. Yen, G. Cunningham, M. Tan, A. Zang, M. Gingras, B. M. N., H. Stickler, K. Serniak, M. E. Schwartz, K. P. O’Brien “Near-ultrastrong nonlinear light-matter coupling in superconducting circuits” arXiv:2404.19199 (2024)
[6] Y. Ye, J. B. Kline, S. Chen, A. Yen, K. P. O’Brien “Ultrafast superconducting qubit readout with the quarton coupler” Science Advances 10 (41), eado9094 (2024)
https://lbnl.zoom.us/j/98854322464?pwd=[REDACTED]
Meeting ID: 988 5432 2464

Passcode: [REDACTED]

Speaker: Michael Williams (LBNL) - Title: First Above-Ground Dark Matter Search Results from the TESSERACT Collaboration
2025-04-24 16:00
Research Progress Meeting
Date: April 24, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Michael Williams (LBNL)
Title: First Above-Ground Dark Matter Search Results from the TESSERACT Collaboration
Abstract: The TESSERACT collaboration will search for dark matter particles with masses below that of the proton using two novel, ultra-sensitive detector technologies: SPICE and HeRALD. These detectors are designed to deliver world-leading sensitivity to a broad range of low-mass dark matter candidates. In this talk, I will share recent progress in the development of Transition Edge Sensors (TESs) with sub-eV energy resolution, a critical advancement enabling the next generation of low-mass dark matter searches. I will focus on our improved understanding of the “low energy excess” background commonly observed in cryogenic detectors, along with new techniques developed to discriminate this background from potential signals. This will culminate in discussion of TESSERACT’s first above-ground dark matter search, which achieved world-leading sensitivity to dark matter masses below 87 MeV/c², powered by the most sensitive athermal phonon sensors ever deployed.
https://lbnl.zoom.us/j/98854322464?pwd=[REDACTED]

Meeting ID: 988 5432 2464

Passcode: [REDACTED]

Speaker: Victoria Xu (UCB) - Title: Broadband quantum enhancement of the LIGO detectors with frequency-dependent squeezing
2025-04-17 16:00 - 17:00
Research Progress Meeting
Date: April 17, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Victoria Xu (UCB)
Title: Broadband quantum enhancement of the LIGO detectors with frequency-dependent squeezing
Abstract: Quantum noise imposes a fundamental limitation on the sensitivity of laser-interferometric gravitational-wave detectors like LIGO, manifesting as shot noise and quantum radiation pressure noise. We present the realization of frequency-dependent squeezing for the fourth astrophysical observing run of the LIGO detectors, resulting in the reduction of both shot noise and quantum radiation pressure noise, alongside broadband detector sensitivity enhancement from tens of hertz to several kilohertz. We further show that frequency-dependent squeezing enables astrophysical operation with quantum noise squeezed below the Standard Quantum Limit by almost 3 dB around 50 Hz, where the LIGO detectors are most astrophysically sensitive. Frequency-dependent squeezing was enabled by the addition of a 300-meter-long in-vacuum filter cavity at each detector, as part of the A+ upgrade to Advanced LIGO. For the LIGO Hanford detector, squeezing reduced the detector noise power by ~5 dB near 1 kHz; for the Livingston detector, detector noise power was reduced by ~6 dB. Combined with technical noise improvements, the quantum upgrade to frequency-dependent squeezing has expanded the detectors’ astrophysical range by almost 20% with respect to no squeezing, and thus improved astrophysical trigger rates by up to 70% during the ongoing fourth observing run of the LIGO detectors.
https://lbnl.zoom.us/j/98854322464?pwd=[REDACTED]

Meeting ID: 988 5432 2464

Passcode: [REDACTED]

Speaker: Harry Teplitz (Caltech/IPAC) - Title: Euclid: an ESA Mission with NASA Involvement to Study the Dark Universe
2025-04-08 16:00 - 17:00
Research Progress Meeting
Date: April 8, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Harry Teplitz (Caltech/IPAC)
Title: Euclid: an ESA Mission with NASA Involvement to Study the Dark Universe
Abstract: Euclid is a European Space Agency mission with NASA involvement to study the geometry and nature of the dark universe. It is optimized for two of the primary probes of dark energy: weak gravitational lensing and galaxy clustering. Euclid launched on 1 July 2023 on a SpaceX Falcon 9 from Cape Canaveral. During its 6 year primary mission, Euclid will survey over 13,000 sq.deg. of extragalactic sky and obtain optical images (530-920nm band), near-infrared images (Y,J,H) and slitless near-infrared grism spectra (1206nm-1892nm, R~480). All Euclid data will be made public to the world community after a proprietary period. Euclid’s first large data set of over 60 square degrees was released on March 19, 2025 (Quick Release 1 or Q1), and the first year of data (about 2000 square degrees) will be released in 2026. I will give an overview of Euclid’s science goals, observing status, and the Q1 data and results.

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Meeting ID: 956 7989 2182
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Speaker: Daniela Köck (University of Oregon) - Title: Exploring Electroweak Paths Beyond the Standard Model with ATLAS
2025-03-27 16:00 - 17:00
Research Progress Meeting
Date: March 27, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Daniela Köck (University of Oregon)
Title: Exploring Electroweak Paths Beyond the Standard Model with ATLAS
Abstract: Phenomenological observations such as dark matter in the universe have long hinted at physics beyond the Standard Model of Particle Physics. The Large-Hadron-Collider (LHC) at CERN has unprecedented capabilities to narrow down on models beyond the Standard Model. Hunting for supersymmetric particles has been a part of the search program since the start of the LHC. Even with these extensive explorations, some well-motivated unexplored parameter spaces only now start to become accessible.
This presentation will give an overview of the current status of searches for supersymmetry produced in electroweak interactions with the ATLAS detector. It will give an overview of the search programme carried out throughout Run-2 of the LHC, discuss a few recent highlights and motivate the necessity of future searches for electroweak supersymmetry.
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Meeting ID: 988 5432 2464

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Speaker: Dean Robinson (LBNL) - Title: New Theory Tools for the Next Generation of Precision Flavor
2025-03-20 16:00 - 17:00
Research Progress Meeting
Date: March 20, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Dean Robinson (LBNL)
Title: New Theory Tools for the Next Generation of Precision Flavor
Abstract: The interpretation of upcoming precision flavor data will require a suite of higher-order calculations and theory descriptions for heavy flavor hadronic processes. We’ll discuss new developments and insights in heavy quark effective theory, that show promise to enable the next generation of precision semileptonic measurements and the interpretation and/or resolution of longstanding anomalies. We’ll also discuss status and plans for the Hammer software library, that is now used across the semileptonic experimental program.
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Meeting ID: 988 5432 2464

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Speaker: Andrei Cuceu (LBNL) - Title: DESI DR2 results: Measurements of Baryon Acoustic Oscillations and Cosmological Constraints
2025-03-19 15:00 - 16:00
Research Progress Meeting
Date: March 19, 2025
Time: 3:00- 4:00 pm
Location: B50 Auditorium [In-Person and HYBRID]
Speaker: Andrei Cuceu (LBNL)
Title: DESI DR2 results: Measurements of Baryon Acoustic Oscillations and Cosmological Constraints
Abstract: The Dark Energy Spectroscopic Instrument (DESI) is conducting a 5-year redshift survey of 40 million extra-galactic sources over 14,000 square degrees of the northern sky. One of its primary goals is to measure the cosmic expansion history across a wide range of redshifts using baryon acoustic oscillations (BAO). The first DESI results, released in 2024, were based on the first year of data and showed intriguing hints that dark energy may not be described by a cosmological constant. On March 19th we will announce a new set of BAO measurements which are based on the first three years of DESI data. We will also present the cosmological implications of these measurements alone and in combination with cosmic microwave background, supernovae, and weak lensing experiments. These include constraints on the expansion rate of the Universe, the nature of dark energy, and the sum of the neutrino masses.
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Meeting ID: 919 5791 3705
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Speaker: Isobel Ojalvo (Princeton) - Title: Real-time Anomaly Detection at the CMS Experiment
2025-03-13 16:00 - 17:00
Research Progress Meeting
Date: March 13, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Isobel Ojalvo (Princeton)
Title: Real-time Anomaly Detection at the CMS Experiment
Abstract: During Run-3 at the LHC, the search for new physics has significantly expanded. Development of advanced algorithms for the Level-1 trigger, encompassing techniques such as Long-Lived Particles, Data Scouting, and Muon showers to ensure broad data selection at the CMS experiment. Here, we introduce CICADA (Calorimeter Image Convolutional Anomaly Detection Algorithm), a state-of-the-art, fully autonomous AI algorithm engineered to process LHC event data in real-time and trigger on anomalous topologies. Operating directly on the rawest recorded data – the calorimeter energy deposits – CICADA demonstrates sensitivity to Standard Model processes. It unveils potential for Beyond the Standard Model Physics, including the exploration of previously untapped phase space at the LHC. We will also delve into future prospects for triggering at the CMS experiment during the HL-LHC era.
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Meeting ID: 988 5432 2464

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Speaker: Ryan Bouabid (Duke) - Title: COHERENT: Using Small Recoils to Look for Big Discoveries
2025-02-27 16:00 - 17:00
Research Progress Meeting
Date: February 27, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Ryan Bouabid (Duke)
Title: COHERENT: Using Small Recoils to Look for Big Discoveries
Abstract: The COHERENT collaboration is pioneering the study of Coherent Elastic Neutrino-Nucleus Scattering (CEvNS), a process only recently observed. Using the Spallation Neutron Source at Oak Ridge National Laboratory, COHERENT has deployed a suite of detectors using diverse technologies and targets. This talk will provide an overview of the collaboration’s experimental efforts and status. Beyond the initial measurements of CEvNS, COHERENT’s results have opened new avenues of discovery potential.
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Meeting ID: 988 5432 2464

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Speaker: Atsushi J. Nishizawa (Gifu Shotoku Gakuen University) - Title: Subaru HSC medium band filter survey and photometric redshift of galaxies
2025-02-25 16:00 - 17:00
Research Progress Meeting
Date: February 25, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Atsushi J. Nishizawa (Gifu Shotoku Gakuen University)
Title: Subaru HSC medium band filter survey and photometric redshift of galaxies
Abstract: Photometric redshift (photo-z) is a well-known technique for measuring the redshift of galaxies using imaging observations. The most challenging aspect of photo-z estimation is that the available information is quite limited, as most imaging surveys utilize broad-band filters, resulting in relatively low wavelength resolution. Traditionally, photo-z is measured by fitting model galaxy spectral energy distributions (SEDs) to the observed fluxes and determining the optimal redshift for each galaxy. An alternative approach is to estimate redshifts using machine learning methods, which can learn complex relationships between observables and redshift.
However, significant improvement in photo-z accuracy is unlikely without incorporating additional information. One possible avenue is to extend the wavelength coverage, while another is to improve the wavelength resolution. We are currently developing medium-band filters to be installed on the Hyper-Suprime Cam at the prime focus of the Subaru Telescope. These medium-band filters will offer moderate spectral resolution and high spatial resolution, providing a substantial amount of additional information. We are preparing to conduct a medium-band filter survey in the coming semesters. In this talk, we will introduce several science cases in collaboration with Euclid, the Roman Space Telescope, DESI-II, and the Subaru Prime Focus Spectrograph (PFS).
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Speaker: Aishik Ghosh (UCI), Title: Overcoming challenges of quantum interference in Higgs physics with high-dimensional statistics
2025-02-20 16:00 - 17:00 | 50A-5132 Sessler-Join Zoom
Abstract: Quantum interference between signal and background Feynman diagrams produce non-linear effects that challenge core assumptions going into the statistical analysis methodology in particle physics. I show that for such cases, no single observable can capture all the relevant information needed to perform optimal inference of theory parameters from data collected in our experiments. The optimal data analysis strategy is to perform statistical inference directly on high-dimensional data, without relying on summary histograms. Neural Simulation-Based Inference (NSBI) is a class of techniques that naturally handle high dimensional data, avoiding the need to design low-dimensional summary histograms. We design a general purpose statistical framework in the ATLAS experiment that enables the application of NSBI to full-scale physics analyses, leading to a second publication of the Higgs width measurement on Run2 data, significantly outperforming the previous measurement punished by the experiment on the same data.
Tea and cookies will be served from 3:45 – 4:00 pm in the Sessler conference room.
If you’d like to meet with the speaker, please send your request to Liz Worthy.
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Meeting ID: 988 5432 2464
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Speaker: Krishna Rajagopal (MIT) - Title: Novel Probes of the Primordial Liquid
2025-02-13 16:00 - 17:00
Research Progress Meeting
Date: February 13, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Krishna Rajagopal (MIT)
Title: Novel Probes of the Primordial Liquid
Abstract: Heavy ion collisions reproduce droplets of the trillions-of-degrees-hot liquid that filled the microseconds-old universe, conventionally called quark-gluon plasma (QGP) but better thought of as hot quark soup. Over the past twenty years, data obtained via recreating this primordial fluid have shown that it is the most liquid liquid in the universe, making it the first complex matter to form as well as the source of all protons and neutrons. After a look at what we have learned about the formation and properties of this original liquid from heavy ion collisions, I will focus on the road ahead, in particular on new probes being developed to answer questions like: How does a strongly coupled liquid emerge, given that what you will see if you can probe QGP with high resolution is weakly coupled quarks and gluons? How can we use jets to see the inner workings of QGP and answer this question? And how does the droplet of QGP ripple after it has been probed by a passing jet?
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Speaker: Nicole Yunger Halpern (NIST + QuICS + University of Maryland) - Title: Quantum thermodynamics for lattice gauge theories
2025-01-23 16:00 - 17:00
Research Progress Meeting
Date: January 23, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Nicole Yunger Halpern (NIST + QuICS + University of Maryland)
Title: Quantum thermodynamics for lattice gauge theories
Abstract: A key objective in nuclear and high-energy physics is to describe nonequilibrium dynamics of matter, e.g., in the early universe and in particle colliders, starting from the Standard Model. Classical-computing methods, via the framework of lattice gauge theory, have experienced limited success in this mission. Quantum simulation of lattice gauge theories holds promise for overcoming computational limitations. Because of local constraints (Gauss’s laws), lattice gauge theories have an intricate Hilbert-space structure. This structure complicates the definition of thermodynamic properties of systems coupled to reservoirs during equilibrium and nonequilibrium processes. We show how to define thermodynamic quantities such as work and heat using strong-coupling thermodynamics, a framework that has recently burgeoned within the field of quantum thermodynamics. Our definitions suit instantaneous quenches, simple nonequilibrium processes undertaken in quantum simulators. To illustrate our framework, we compute the work and heat exchanged during a quench in a Z2 lattice gauge theory coupled to matter in 1+1 dimensions. The thermodynamic quantities, as functions of the quench parameter, evidence an expected phase transition.
Reference: Davoudi, Jarzynski, Mueller, Oruganti, Powers, and NYH, Phys. Rev. Lett. 133, 250402 (2024). https://journals.aps.org/prl/abstract/10.1103/ PhysRevLett.133.250402
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Speaker: Lloyd Knox (UC Davis) - Title: A Polarized Look at the Hubble Constant Problem
2025-01-16 16:00 - 17:00
Research Progress Meeting
Date: January 16, 2025
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Lloyd Knox (UC Davis)
Title: A Polarized Look at the Hubble Constant Problem
Abstract: The standard cosmological model has met with enormous empirical success over the past two decades. Continued testing of the model is highly warranted as it relies on additional components beyond the standard model of particle physics: the cold dark matter, the cosmological constant, and some mechanism for generating initial density perturbations. Additional motivation comes from a number of empirical suggestions of deficiencies in the model, with the most statistically significant among these a mismatch between different methods for determining the current rate of the expansion of space (the Hubble constant). In this talk I will present our use of cosmic microwave background (CMB) polarization data from the third generation camera on the South Pole Telescope (SPT-3G) to provide stringent tests of the standard cosmological model and determine the Hubble constant with a standard error of 1.2% using CMB polarization data alone.
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Speaker: Ryan Gibbons (UC Berkeley) - Title: Searching for Dark Matter with LZ and Future LZ Upgrades
2024-12-19 16:00 - 17:00
Research Progress Meeting
Date: December 19, 2024
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Ryan Gibbons (UC Berkeley)
Title: Searching for Dark Matter with LZ and Future LZ Upgrades
Abstract: Direct detection of particle dark matter remains an outstanding opportunity in understanding the nature of the universe, and for discovery of physics beyond the Standard Model. I will discuss the LUX-ZEPLIN (LZ) experiment’s world-leading WIMP dark matter searches as well as a novel search for neutrinoless double beta decay. In addition, I will present three avenues of instrumentation work at LBNL for potential upgrades to the LZ experiment: a solid xenon TPC (crystaLiZe), light element doping of xenon (HydroX), and mitigation of instrument backgrounds to enable sub-GeV dark matter searches.
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Speaker: Sparshita Dey (Oxford) - Title: Chasing Shadows: Illuminating the Path from LZ to the Next Generation Dual-Phase Xe TPC Observatory for Dark Matter
2024-12-17 16:00 - 17:00
Research Progress Meeting
Date: December 17, 2024
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Sparshita Dey (Oxford)
Title: Chasing Shadows: Illuminating the Path from LZ to the Next Generation Dual-Phase Xe TPC Observatory for Dark Matter
Abstract: The nature of dark matter remains one of the most significant unsolved challenges in modern physics. Liquid xenon time projection chambers (LXe-TPCs) have emerged as a powerful tool in the search for WIMP dark matter candidates (Weakly Interacting Massive Particles), particularly in the GeV/c2 range. The XENON-LUX-ZEPLIN-DARWIN (XLZD) collaboration embodies the collective knowledge & expertise of generations of LXe-TPC-based experiments, combining three current world-leading experimental and R&D efforts operating at sub-10-tonne Xe target masses. This talk will present the case for XLZD’s next-generation dual phase xenon observatory for dark matter and neutrino physics, with the capability to explore the WIMP parameter space down to the so-called neutrino fog, a background-limited region where neutrino and WIMP signatures look very similar. A discussion of the lessons learned from the operation & analysis chain for the LUX-ZEPLIN experiment will feature, to motivate the design approach for this detector, as well as an overview of novel detector design concepts and exciting current R&D experiments which may both improve sensitivities to low-mass dark matter models and revolutionise the current dark matter direct detection landscape.
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Speaker: Shion Kubota (Harvard) - Title: Studying neutrinos in high definition with LAr
2024-12-12 16:00 - 17:00
Research Progress Meeting
Date: December 12, 2024
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Shion Kubota (Harvard)
Title: Studying neutrinos in high definition with LAr
Abstract: This talk explores recent advancements in neutrino physics, with a focus on innovative detector technologies developed for the Deep Underground Neutrino Experiment (DUNE). It delves into the use of Liquid Argon Time Projection Chambers (LArTPCs), discussing the challenges associated with the Anode Plane Assembly’s (APA) quality control and how the Digital Wire Analyzer (DWA) has improved the efficiency of wire tension testing. Additionally, the presentation introduces the Q-Pix readout architecture, a promising approach to pixelated detection that streamlines data handling and enhances studies of supernova neutrinos. Simulation results highlight Q-Pix’s potential to improve event reconstruction, extend detection capabilities, and reduce data demands, offering exciting possibilities for future kiloton-scale neutrino experiments.
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Speaker: Tyler Horoho (U. of Virginia) - Title: Searching for sub-GeV Dark Matter with the NOvA Near Detector and Measuring the Performance of the Mu2e Cosmic Ray Veto
2024-12-10 16:00 - 17:00
Research Progress Meeting
Date: December 10, 2024
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Tyler Horoho (U. of Virginia)
Title: Searching for sub-GeV Dark Matter with the NOvA Near Detector and Measuring the Performance of the Mu2e Cosmic Ray Veto
Abstract: The constituents of dark matter are still unknown, and the viable possibilities span a very large mass range. Specific scenarios for the origin of dark matter sharpen the focus to within about an MeV to 100 TeV. Most of the stable constituents of known matter have masses in this lower range, and a thermal origin for dark matter works in a simple and predictive manner. If there is a non-gravitational interaction between dark matter and ordinary matter, as there must be in the case of a thermal origin, then there is necessarily a production mechanism in accelerator-based experiments. NOvA is a high luminosity long-baseline neutrino oscillation experiment at Fermilab that is capable of searching for signatures of dark matter re-scattering with electrons in its near detector after production in the NuMI target. In this talk, I present an analysis to search for an excess of single electron events in the NOvA near detector consistent with the presence of dark matter-electron scattering and show the expected sensitivity of NOvA to sub-GeV dark matter. I will also discuss a future search for sub-GeV dark matter with the Light Dark Matter eXperiment (LDMX), a planned electron-beam fixed-target missing-momentum search for dark matter at SLAC.
The Mu2e experiment at Fermilab will search for charged-lepton flavor violation through the neutrino-less conversion of a muon to an electron in the presence of a nucleus, a sensitive probe for new physics. Mu2e aims to have single-event sensitivity four orders of magnitude beyond current experimental limits. This sensitivity will require less than one expected background event, which will only be possible with sufficient background vetoing. The largest source of background comes from cosmic-rays, which can produce electrons indistinguishable from a conversion electron signature. To mitigate this, Mu2e will use a cosmic ray veto (CRV), which must exceed a veto efficiency of 99.99% to meet Mu2e’s sensitivity goals. I will present performance studies on the CRV detector components.
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Speaker: Cole Kampa (Northwestern U.) - Title: From Muon CLFV to Collider EFT: Advances in New Physics Searches
2024-12-05 16:00 - 17:00
Research Progress Meeting
Date: December 5, 2024
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Cole Kampa (Northwestern U.)
Title: From Muon CLFV to Collider EFT: Advances in New Physics Searches
Abstract: Mu2e, the muon-to-electron conversion experiment at Fermilab, will search for Charged Lepton Flavor Violation (CLFV) – an accidental symmetry forbidden in the Standard Model (SM) of particle physics. Observing CLFV would provide unambiguous evidence of New Physics (NP) beyond the SM. I will briefly outline the experimental design and methodology of Mu2e, emphasizing ongoing efforts to ensure robust physics results. Notably, the introduction of an unbinned maximum likelihood fit has improved the expected sensitivity to Rμe, the muon-to-electron conversion rate, by up to 20%. On the apparatus side, a key component of the experiment is the tracking detector, which reconstructs electron trajectories in a uniform magnetic field. Studies of numerical calculations of the field suggest the calculations should predict the field with 1e-3 level accuracy. However, a 1e-4 level accuracy is required to distinguish signal electrons from the dominant muon decay-in-orbit (DIO) background. To meet this challenge, a custom field mapping apparatus is being developed. The measured field data will be modeled using a novel approach that combines least-squares fitting with a scalar physics-informed neural network (PINN), achieving a modeling fidelity significantly better than the 1e-4 accuracy requirement. I will conclude the CLFV discussion with an overview of two next-generation experiments: Mu2e-II and the Advanced Muon Facility (AMF).

The energy frontier offers a complementary path to NP discovery. Although direct searches at the Large Hadron Collider (LHC) have yet to yield definitive signs of NP, many efforts now focus on model agnostic approaches such as Effective Field Theory (EFT). Recently, the Compact Muon Solenoid (CMS) collaboration observed SM triboson (VVV) production. Building on this milestone, an ongoing CMS analysis employs an EFT framework to constrain heavy NP given the observed rate of VVV. I will conclude by discussing the statistical combination of the various final states being explored in this analysis.
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Speaker: Simon Koch (Oxford) - Title: Measurements with ATLAS, Measurements of ATLAS: A search for leptoquarks in a final state with two tau leptons, and material measurements of the ITk Pixel detector
2024-12-03 16:00 - 17:00
Research Progress Meeting
Date: December 3, 2024
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Simon Koch (Oxford)
Title: Measurements with ATLAS, Measurements of ATLAS: A search for leptoquarks in a final state with two tau leptons, and material measurements of the ITk Pixel detector
Abstract: The ATLAS detector at the LHC has enjoyed great success so far, spanning both new discoveries and precision measurements, and tests of a vast array of theoretical models. This seminar will begin with an introduction to the ATLAS high-mass Drell-Yan di-tau measurement and in particular the search for leptoquarks in this decay channel, including the analysis design and expected results. The search was originally motivated by hints toward lepton-flavour-universality violating behaviour at LHCb, and the leptoquark models explored couple the lepton and quark sectors of the standard model via a new vector or scalar boson. This also introduces unique properties and challenges to the analysis, such as the impact of negative interference with the standard model cross-section.
The future should bring an even greater physics reach thanks to the larger datasets that will be made possible by the High-Luminosity LHC and the ATLAS Inner Tracker (ITk) upgrade. The tracking and vertexing performance of the ITk is critical for future analyses, and hence factors influencing detector performance must be validated so they can be correctly implemented in our Monte-Carlo simulations. One important aspect is the material content of the detector, which has a substantial impact on b-tagging and vertexing resolution due to multiple scattering and hadronic interactions, and is generally only verified using detector data post-commissioning. The second part of this seminar will explore a series of testbeam measurements utilising multiple scattering of low-energy positrons to measure 2D maps of the fractional radiation length x/X₀ of detector components to sub-mm resolution during the R&D phase. A measurement of an ITkPix quad module will be presented, and an outlook will be given on the feasibility of measuring large areas quickly and efficiently with such a technique.
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Speaker: Gillian Kopp (Princeton University) - Title: Enabling Novel Long-Lived Particle Searches through 5D Calorimetry in the CMS Experiment
2024-11-21 16:00 - 17:00
Research Progress Meeting
Date: November 21, 2024
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Gillian Kopp (Princeton University)
Title: Enabling Novel Long-Lived Particle Searches through 5D Calorimetry in the CMS Experiment
Abstract: The Compact Muon Solenoid (CMS) experiment records proton-proton collisions from the LHC to measure properties of the Standard Model and search for new physics. Recently, long-lived particles have emerged as a compelling direction in which to search for physics beyond the Standard Model. As these searches are typically limited by the event selection, implementing dedicated long-lived particle (LLP) triggers provides an excellent avenue to expand experimental coverage into this challenging parameter space. A novel hardware-level LLP trigger has been developed and implemented in the CMS experiment for Run 3 (2022-2026), exploiting the recent hadron calorimeter (HCAL) upgrade. The hardware- and firmware-based trigger algorithm identifies delayed jets, resulting from the decay of massive LLPs, and displaced jets, resulting from LLPs that decay inside the HCAL. This approach significantly increases sensitivity to LLP signatures with soft hadronic final states, including exotic decays of the Higgs boson. I review the trigger implementation, calibration, and performance, showing results from recent HCAL timing scans that produce artificially delayed jets. The data collected with the new triggers provides a first look at the capabilities to capture softer events and expand the phase space accessible in LLP searches.
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Speaker: Claire Lamman (Harvard) - Title: Untangling the Cosmic Web: Correlations between small-scale clustering and large-scale structure
2024-11-12 16:00 - 17:00
Research Progress Meeting
Date: November 12, 2024
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Claire Lamman (Harvard)
Title: Untangling the Cosmic Web: Correlations between small-scale clustering and large-scale structure
Abstract: Gravitational forces from the largest structures in the Universe leave a detectable imprint on galaxies and their local environment. I will present a new approach to tracing the tidal field using these correlations: the intrinsic alignment of small groups of galaxies, or “multipelts”. Multiplets mostly consist of 2-4 galaxies within 1 Mpc/h of each other, and we measure their orientations relative to the galaxy-traced tidal field. Using spectroscopic redshfits from the DESI Y1 survey, we detect intrinsic alignment out to projected separations of 100 Mpc/h and beyond redshift 1. We find a simillar signal regardless of galaxy luminosity or color, which could make multiplet alignment a useful tool for mapping the direction of the tidal field and any cosmological effects which impact it. Our detection demonstrates that galaxy clustering in the non-linear regime of structure formation preserves an interpretable memory of the large-scale tidal field.

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