Publications – Physics

Creating Pileups of Eccentric Planet Pairs Wide of Mean Motion Resonances through Divergent Migration

lynn — Thu, 20 Nov 2025 22:26:22 +0000

Jingyun Lin?(�־��),?Ivan Dudiak,?Samuel Hadden, and?Daniel Tamayo

The Astrophysical Journal, 994, 123 (2025).

Abstract

Observed pileups of planets with period ratios ��1% wide of strong mean motion resonances (MMRs) pose an important puzzle. Early models showed that they can be created through sustained eccentricity damping, driving a slow separation of the orbits, but this picture is inconsistent with elevated eccentricities measured through transit-timing variations (TTVs). We argue that any source of divergent migration (tides, planet�Cdisk interactions, etc.) will cause planets that encounter an MMR to both jump over it (piling up wide of resonance) and get a kick to their eccentricities. We find that normalizing observed deviations from resonance by the value at which the pair would encounter and jump over the resonance leads to a significantly clearer trough narrow of the resonance. We additionally find that the jumps in eccentricity expected from slow MMR crossings are sufficiently large to explain the scale of eccentricities measured through TTVs, though some residual eccentricity damping would be required to quantitatively match observations.

Closing in on singly charged scalars

OCM — Tue, 02 Sep 2025 07:00:00 +0000

Snehadri Das, Will Howe, Brian Shuve*, David Tucker-Smith, Ruby Yager

Physical Review D 112, 055003 (2025)

Abstract

We investigate current experimental constraints and future search prospects for a hypothetical ? ?(2) and ? ?(3) singlet spin-zero particle that carries unit electric charge: a singly charged scalar (SCS). In addition to providing useful benchmarks for collider searches, SCS particles are also well-motivated ingredients in relatively minimal dark sectors. We focus on scenarios in which the SCS decays promptly at colliders to a lepton plus either a neutrino or an invisible dark-sector particle of negligible mass. A promptly decaying SCS can easily have appreciable branching ratios to more than one lepton flavor while remaining consistent with constraints on lepton flavor violation. This broadens the allowed range of SCS masses to extend well beyond those for right-handed selectrons, smuons, or staus. For particular benchmark SCS branching ratios, we find that SCS masses above ��185 GeV and in a lower-mass window ��80�C125 GeV are still allowed at 95% confidence level. We carry out Monte Carlo simulations to explore the potential of a boosted-decision-tree-based analysis to probe the surviving SCS parameter space in future searches at the (HL-)LHC, finding a significant increase in sensitivity relative to cut-based analyses both in the lower-mass window and at higher SCS masses.

Exchange-symmetrized qudit Bell bases and Bell-state distinguishability

OCM — Wed, 06 Aug 2025 07:00:00 +0000

Oscar Scholin and Theresa W. Lynn*

Physical Review Research 7, 033124 (2025)

Abstract

Entanglement of qudit pairs, with single-particle Hilbert space dimension , has important potential for quantum information processing, with applications in cryptography, algorithms, and error correction. For a pair of qudits of arbitrary even dimension , we introduce a generalized Bell basis with definite symmetry under exchange of internal states between the two particles. We show that no complete exchange-symmetrized basis can exist for odd . This framework extends prior work on exchange-symmetrized hyperentangled qubit bases, where is a power of 2. For our exchange-symmetrized basis, we show that measurement devices restricted to linear evolution and local measurement (LELM) can unambiguously distinguish 2? ?1 qudit Bell states for any even . This achieves the upper bound in general for reliable Bell-state distinguishability via LELM and augments previously known limits for =2 and =3. This result is relevant to near-term realizations of quantum communication protocols.

Towards satellite tests combining general relativity and quantum mechanics through quantum optical interferometry: progress on the deep space quantum link

OCM — Fri, 20 Jun 2025 07:00:00 +0000

Makan Mohageg, Charis Anastopoulos, Olivia Brasher, Jason Gallicchio*, Bei Lok Hu, Thomas Jennewein, Spencer Johson, Shih-Yuin Lin, Alexander Ling, Alexander Lohrmann, Christoph Marquardt, Luca Mazzarella, Matthias Meister, Raymond Newell, Albert Roura, Giuseppe Vallone, Paolo Villoresi, Lisa Worner, and Paul Kwiat

EPJ Quantum Technology 12, 78 (2025)

Abstract

The Deep Space Quantum Link (DSQL) is a space-mission concept that aims to explore the interplay between general relativity and quantum mechanics using quantum optical interferometry. This mission concept was formally presented to the United States National Academy of Science Decadal Survey as a research campaign for Fundamental Physics in 2022. Since then, advances have been made in the space-based quantum optical technologies required to conduct a DSQL-type mission. In addition, other research efforts have defined alternative measurement concepts to explore the same scientific questions motivating the DSQL mission. This paper serves as an update to the community on the status of the DSQL mission concept and related research and technology development efforts.

A Unified, Physical Framework for Mean Motion Resonances

lynn — Mon, 02 Jun 2025 21:35:00 +0000

Daniel Tamayo and Samuel Hadden

The Astrophysical Journal 986, 11 (2025).

Abstract

The traditional approach to analyzing mean motion resonances (MMRs) is through the canonical perturbation theory. While this is a powerful method, its generality leads to complicated combinations of variables that are challenging to interpret and require looking up numerical coefficients particular to every different resonance. In this paper, we develop simpler scaling relations in the limit where orbits are closely spaced (period ratios ?2), and interplanetary interactions can be approximated by only considering the close approaches each time the inner planet overtakes the outer at the conjunction. We develop geometric arguments for several powerful results: (i) that p:p ? q MMRs of the same order q are all rescaled versions of one another, (ii) that the general case of two massive planets on closely spaced, eccentric, coplanar orbits can be approximately mapped onto the much simpler case of an eccentric test particle perturbed by a massive planet on a coplanar circular orbit, and (iii) that, while the effects of consecutive conjunctions add up coherently for first-order (p:p ? 1) MMRs, they partially cancel for p:p ? q MMRs with order q > 1, providing a physical explanation for why these higher-order MMRs are weaker and can often be ignored. Finally, we provide simple expressions for the widths of MMRs and their associated oscillation frequencies that are universal to all closely spaced MMRs of a given order q, in the pendulum approximation.

Carving Out the Inner Edge of the Period Ratio Distribution through Giant Impacts

lynn — Fri, 21 Mar 2025 21:42:00 +0000

Kaitlyn Chen, Oswaldo Cardenas, Brandon Bonifacio, Nikolas Hall, Rori Kang, and Daniel Tamayo

The Astrophysical Journal 982, 100 (2025).

Abstract

The distribution of orbital period ratios between adjacent observed exoplanets is approximately uniform, but exhibits a strong falloff toward close orbital separations. We show that this falloff can be explained through past dynamical instabilities carving out the period ratio distribution. Our suite of numerical experiments would have required ��3 million CPU hr through direct N-body integrations, but was achieved with only ��50 CPU hr by removing unstable configurations using the Stability of Planetary Orbital Configurations Klassifier machine learning model. This highlights the role of dynamical instabilities in shaping the observed exoplanet population, and shows that the inner part of the period ratio distribution provides a valuable observational anchor on the giant impact phase of planet formation.

Updates to the FeatureClassifier in the Stability of Planetary Orbital Configurations Klassifier

lynn — Sun, 16 Feb 2025 22:24:00 +0000

Elio Thadhani, Yanming Ba (��), Hanno Rein, and Daniel Tamayo

Research Notes of the AAS 9, 27 (2025).

Abstract

The Stability of Planetary Orbital Configurations Klassifier (SPOCK) package collects machine learning models for predicting the stability and collisional evolution of compact planetary systems. In this paper we explore improvements to SPOCK��s binary stability classifier (FeatureClassifier), which predicts orbital stability by collecting data over a short N-body integration of a system. We find that by using a system-specific timescale (rather than a fixed 10⁴ orbits) for the integration, and by using this timescale as an additional feature, we modestly improve the model��s AUC metric from 0.943 to 0.950 (AUC = 1 for a perfect model). We additionally discovered that ��10% of N-body integrations in SPOCK��s original training data set were duplicated by accident, and that <1% were misclassified as stable when they in fact led to ejections. We provide a cleaned data set of 100,000+ unique integrations, release a newly trained stability classification model, and make minor updates to the API.

Orbital Migration Through Atmospheric Mass Loss

lynn — Wed, 11 Dec 2024 22:14:00 +0000

Benjamin Hanf, William Kincaid, Hilke Schlichting, Livan Cappiello, and Daniel Tamayo

The Astronomical Journal 169, 19 (2024)

Abstract

Atmospheric mass loss is thought to have strongly shaped the sample of close-in exoplanets. These atmospheres should be lost isotropically, leading to no net migration on the planetary orbit. However, strong stellar winds can funnel the escaping atmosphere into a tail trailing the planet. We derive a simple kinematic model of the gravitational interaction between the planet and this anisotropic wind, and derive expressions for the expected migration of the planet. Over the expected range of parameters, we find typical migrations of a few tenths to a few percent inward. We argue that this modest migration may be observable for planet pairs near mean motion resonances, which would provide an independent observational constraint on atmospheric mass loss models.

Electroweak Axion Portal to Dark Matter

OCM — Tue, 12 Nov 2024 08:00:00 +0000

Stephanie Allen, Albany Blackburn, Oswaldo Cardenas, Zoe Messenger, Ngan Nguyen, and Brian Shuve*

Physical Review D 110, 095010 (2024).

Abstract

Axion-like particles (ALPs) are good candidates for mediators to the dark sector. We explore scenarios in which an ALP mediates interactions between dark matter and electroweak gauge bosons. These models yield testable electromagnetic signals in astrophysical, cosmological, and terrestrial probes. We find promising prospects for both indirect detection and accelerator tests, with interesting parameter space already constrained by current experiments. Our work provides concrete benchmarks for future tests of the electroweak ALP portal.

Accelerating Giant-impact Simulations with Machine Learning

lynn — Wed, 06 Nov 2024 22:33:00 +0000

Caleb Lammers, Miles Cranmer, Sam Hadden, Shirley Ho, Norman Murray, and Daniel Tamayo

The Astrophysical Journal 975, 228 (2024).

Abstract

Constraining planet-formation models based on the observed exoplanet population requires generating large samples of synthetic planetary systems, which can be computationally prohibitive. A significant bottleneck is simulating the giant-impact phase, during which planetary embryos evolve gravitationally and combine to form planets, which may themselves experience later collisions. To accelerate giant-impact simulations, we present a machine learning (ML) approach to predicting collisional outcomes in multiplanet systems. Trained on more than 500,000 N-body simulations of three-planet systems, we develop an ML model that can accurately predict which two planets will experience a collision, along with the state of the postcollision planets, from a short integration of the system��s initial conditions. Our model greatly improves on non-ML baselines that rely on metrics from dynamics theory, which struggle to accurately predict which pair of planets will experience a collision. By combining with a model for predicting long-term stability, we create an ML-based giant-impact emulator, which can predict the outcomes of giant-impact simulations with reasonable accuracy and a speedup of up to 4 orders of magnitude. We expect our model to enable analyses that would not otherwise be computationally feasible. As such, we release our training code, along with an easy-to-use user interface for our collision-outcome model and giant-impact emulator ().