Statistical Mechanics
Directed walks shape a universal square-root law of entropy production rate in nonreciprocal systems
Thiparat Chotibut, Ewa Gudowska-Nowak and Maciej A. Nowak
The
entropy production rate (EPR) quantifies irreversibility of a nonequilibrium steady state, yet standard formulas obscure how a complex interaction network generates it. For multivariate Ornstein-Uhlenbeck dynamics on such networks, we express the EPR as a quadratic form in antisymmetric
matrices measuring the nonreciprocity of aggregate directed walks at every length, and, equivalently, as two weighted-walk quantities: pairs of directed walks sharing both endpoints, and directed closed walks. For diagonalizable interactions, an exact correspondence translates these walk quantities into
eigenvalues and biorthogonal eigenvector overlaps. Across dense, sparse, and deep acyclic random interactions satisfying matched-walk conditions, the mean EPR per node universally follows the square-root law $\phi_*(g)=1-\sqrt{1-g^2}$, where $g \in [0,1)$ parametrizes the interaction strength. Deep acyclic interaction
matrices are nilpotent, with all
eigenvalues fixed at zero for every $g$, yet, as their depth increases, their mean EPR per node approaches $\phi_*(g)$. Thus, the square-root law arises from directed walk properties, rather than from a shared spectral density or specific network
topology.
Read the full abstract ▾
High Energy Physics (Theory)
Tropical Open Strings in a Kalb-Ramond Background
Sarthak Duary, Vi Hong and Sourav Maji
We study tropical open strings arising from the analytically continued action of tropological sigma models in the presence of a constant Kalb-Ramond background. We show that the background field separates the theory into a generic sector and a critical sector. In the generic sector, the canonical structure produces a kinematical nonlocal bracket between the transverse and leafwise target-space coordinates. At the critical value of the Kalb-Ramond field, the Legendre map degenerates and the theory develops a primary constraint, requiring quantization by the Dirac-Bergmann procedure. This critical sector has a finite reduced phase-space structure and differs from the naive limit of the generic theory.
Read the full abstract ▾
Quantum Physics
Real-time decoder for a MegaQuOp quantum computer using a single CPU
Min Ye, Andrii Maksymov and Nicolas Delfosse
As
quantum computers advance toward the regime of MegaQuOp machines executing millions of gates, a decoding system capable of real-time error correction in such a device will be crucial. Recent efforts have been focused on decoding an error-corrected
memory or a small number of logical operations. Here we demonstrate an end-to-end real-time decoding stack for a universal fault-tolerant trapped-ion
quantum computer architecture capable of decoding real workloads with millions of logical gates over hundreds of logical
qubits. The complete pipeline, including on the fly detector error model generation, decoding of all logical
qubits, logical operations, and magic-state factories, runs on a single CPU. We
benchmark the decoder on practically relevant
quantum applications spanning up to 408 logical
qubits, and up to one million $T$ gates. Assuming a trapped-ion architecture with 1 to 5 ms cycle time, the decoding delay stretches the computation by less than $0.3\%$ at $p_{\mathrm{CNOT}}=10^{-4}$ and less than $12\%$ at $p_{\mathrm{CNOT}}=5\times 10^{-4}$ for all workloads studied. These results demonstrate real-time decoding at MegaQuOp scale on a single conventional CPU.
Read the full abstract ▾
Solar and Stellar Astrophysics
A Seismic Technique for Obtaining White Dwarf Fundamental Parameters from Mean Period Spacings and Astrometry
Keaton J. Bell and Agnès Bischoff-Kim
We present a new statistical technique that utilizes the synergy of precision astrometry and time series photometry from modern space missions to obtain reliable physical parameters of pulsating white
dwarf stars. We compute a grid of white
dwarf structural models that span the helium-atmosphere pulsating white
dwarf (DBV) instability strip, showing that mean period spacings between adjacent pulsation modes and absolute magnitudes derived from
Gaia astrometry vary monotonically and in opposing directions across parameter space. While most efforts in white
dwarf asteroseismology to directly fit individual pulsation periods to
stellar models result in degenerate and poorly resolved solutions, the "seismic technique" produces unique and reliable seismic solutions for global parameters of mass and effective temperature when a reliable mean period spacing is detected. Our models sample various physically plausible interior chemical composition profiles based on modern evolutionary models to propagate uncertainty from the precise structures of actual
stars. Once the global
stellar parameters are tightly constrained, seismically resolving white
dwarf interior structures becomes more computationally tractable, and degeneracies can be resolved. This new seismic technique is largely insensitive to the precise absorption line profiles interpreted by the widely used spectroscopic technique, and therefore provides complementary constraints that can be used to test spectroscopic methods. We demonstrate the method for the pulsating helium-atmosphere white
dwarf WD 0158-160 observed by TESS, obtaining $T_\mathrm{eff} = 24584\pm 971$ K and $M_\star = 0.608\pm 0.013$ $M_\odot$.
Read the full abstract ▾
General Relativity and Quantum Cosmology
Exact Integrable $\Lambda$CDM-Mimicking $f(Q)$ Cosmology: Background, Stability, and Perturbations in the First Connection Branch
Wompherdeiki Khyllep, Daniele Gregoris, Saikat Chakraborty et al. (+1 more)
We re-examine the problem of mimicking the standard cosmological model, characterized by $j=1$ (where $j$ is the cosmographic jerk parameter), within the context of the first connection branch of $f(Q)$
gravity. While this problem has previously been addressed via reconstruction techniques$-$yielding the analytic form $f(Q)=-2\Lambda+\alpha Q + \beta\sqrt{-Q}$ with $Q=-6H^2$ $-$here we tackle this problem from two distinct perspectives, applying either a cosmographic closure strategy or an auxiliary-variable hierarchy approach to the traditional dynamical systems formulation. Remarkably, the cosmographic closure renders the dynamical system integrable for $\Lambda$CDM-mimicking $f(Q)$ models. Consequently, we obtain closed-form analytical solutions for all relevant cosmological quantities at both the background and linear perturbation levels, with the perturbative solutions elegantly expressed in terms of generalized Heun functions. Furthermore, we analyze the structural stability of the $\Lambda$CDM-mimicking phase space against small kinematic deviations from $j=1$, demonstrating the robustness of these solutions. Our approach provides a systematic route to studying $\Lambda$CDM-mimicking dynamics without requiring a closed-form analytic reconstruction of the underlying action. Finally, we utilize this framework to establish a direct comparison between $\Lambda$CDM-mimicking dynamics in the first connection branch of $f(Q)$
gravity and those in $f(R)$
gravity.
Read the full abstract ▾
All authors Wompherdeiki Khyllep, Daniele Gregoris, Saikat Chakraborty, Jibitesh Dutta
Quantum Physics
Hardware-Aware Fermion-to-Qubit Mappings for Simulating the 2D Hubbard Model on Heavy-Hexagon Quantum Processors
Alessio Esposito, Andrea Giachero, Zoltàn Zimboràs et al. (+1 more)
Quantum simulation of strongly correlated fermionic systems is among the most promising near- term applications of
quantum computing, but its practical efficiency depends critically on the choice of
fermion-to-
qubit mapping and on the connectivity of the underlying hardware. In this work we address this problem in the context of the two-dimensional Hubbard model, simulated on IBM superconducting
quantum processors with heavy-hexagon connectivity. We numerically
benchmark the Jordan-Wigner, Bravyi-Kitaev, and Bonsai transformations, evaluating their Pauli weight and SWAP overhead across seven heavy-hexagon chips of increasing size. We show that, while the Bravyi-Kitaev mapping initially exhibits a lower Pauli weight, this advantage is eliminated once routing costs are taken into account, confirming the Bonsai mapping as the most hardware-efficient baseline transformation for this architecture. We then use the Bonsai mapping to construct the
qubit Hamiltonian of the 2D spinful
Fermi-Hubbard model, introducing a simulated annealing
algorithm that optimizes the assignment of Majorana strings to
lattice sites, reducing the cost function by nearly 50% percent. Finally, we simulate on
quantum hardware the time
evolution of fermionic states up to 6x6
lattices, confirming the viability of the Bonsai encoding for hardware-aware large-scale two-dimensional simulations.
Read the full abstract ▾
All authors Alessio Esposito, Andrea Giachero, Zoltàn Zimboràs, Leonardo Banchi
Astrophysics of Galaxies
The ionizing properties of JWST's compact broad-line emitters
Sara Mascia, Jorryt Matthee, Alberto Torralba et al. (+4 more)
The recent JWST discovery of a numerous population of broad-line emitters (BLEs) at $z>4$ has reopened the question of whether sources other than faint
galaxies contributed significantly to
cosmic reionization. To assess this contribution, we present a systematic census of compact, blue broad-line emitters at $4\leq z\leq7$ selected from the DJA, designed to isolate sources in which the UV continuum and the broad-line emission originate from the same compact physical region. Starting from a parent sample of 4145
galaxies with NIRSpec/PRISM spectroscopy and NIRCam imaging, we apply criteria on broad Ha emission (FWHM$>2000$km s-1, detected at S/N$\geq5$, complete at $L_{Ha,broad}\geq10^{42.7}$erg s-1), blue continuum slopes ($\beta_{UV}\leq-1.5$, $\beta_{opt}<0.5$), and morphological compactness in both the rest-frame UV and optical, returning a final sample of 20 sources. This constitutes $\sim20%$ of the PRISM-selected broad-line sample, which is dominated by Little Red Dots (LRDs). We find that the compact blue BLEs display hot ionizing continua, high-ionization UV lines (CIV, NIV], HeII), and elevated Lya emitter fractions ($X_{Lya}=50-67%$) relative to
star-forming
galaxies and LRDs. Beyond their similar lack of X-ray emission, their optical spectra closely resemble those of LRDs. This suggests that compact blue BLEs extend this population towards lower column density envelopes, but with similar engines, rather than representing a physically distinct population. Using Sirocco to model physical configurations that reproduce the observed spectra, we find a high ionizing
photon production efficiency (log$\xi_{ion}\sim25.4$Hz erg-1) and a weighted average escape fraction $fesc\sim0.2$ for the bluest sources, and $\sim0.01$ for LRDs. This implies that broad-line sources do not dominate reionization globally, but given their luminosity, their contribution can dominate up to few Mpc scales.
Read the full abstract ▾
All authors Sara Mascia, Jorryt Matthee, Alberto Torralba, Jenny E. Greene, Anna-Christina Eilers, Edoardo Iani, Rohan P. Naidu
Accelerator Physics
High-charge collimated and energy-selected laser-driven MeV electron beams produced by magnetic selection
I. Cohen, I. Slabu, Q. Peysson et al. (+16 more)
We have developed a compact passive energy-selector for MeV-range electrons produced by irradiating solid targets by ultra-intense short-pulse
lasers. The device allows for generating electron beams with a variable energy spread over a broad range of energies, from tens of keV to tens of MeV. Here we have demonstrated its use by producing electrons from solid targets in the MeV range and with a ~10% bandwidth, thereby compensating the intrinsic broadband nature of the electrons produced from such source. Coupled with a pulsed
magnetic field to further compensate the intrinsic large divergence of this source, it allows to produce a highly-collimated beam of narrow-band and ultra-fast electrons, suitable for a wide range of applications, e.g. radiation therapy or time-resolved electron probing.
Read the full abstract ▾
All authors I. Cohen, I. Slabu, Q. Peysson, S. Dorard, Y. Abe, J. Béard, T. Moraine, S.N. Chen, A. Chessa, K.Iida, P. Kempski, Y. Kuramitsu, H. Kusano, F. Nikaido, M. Ruszkowski, K. Sakai, N. Tamaki, O. Tesileanu, J. Fuchs
Solar and Stellar Astrophysics
EncoTESS: Age-Sensitive Encodings from Raw TESS Light Curves
Phil R. Van-Lane, Joshua S. Speagle, Ryan Cloutier et al. (+3 more)
Main sequence
stars of spectral types late F through M exhibit systematic variability in photometric light curves, particularly when they are young. Rotational modulation of starspots manifests as quasi-sinusoidal variability, which enables the measurement of rotation periods. Variability can also be
stochastic, as in
stellar flaring. However, since measurements of
stochastic processes depend on the time of observation, they are typically noisier. Considering that different manifestations of variability have unique observational nuances, models that naturally unify these are incredibly useful for
stellar characterization. Towards this goal, we have developed EncoTESS: a Time Series Foundation Model (TSFM) trained on a subset of TESS 2-min light curves. EncoTESS is specifically designed to handle the observational noise, heteroskedastic measurements, irregular sampling, and large data gaps common to TESS data. It is also ~1% of the size of a typical literature TSFM, so can be run easily on a modern laptop. EncoTESS encodes light curves into a fixed-size latent parameter space, which can be used to infer physical
stellar properties and recovers light curve summary statistics well. EncoTESS outperforms rotation period and variability amplitude as age indicators for
stars that have not converged onto the slow rotator sequence yet; broadly these include K and M
stars less than ~100 Myr, and M
stars less than ~1 Gyr. We focus on age inference as an application of EncoTESS in this work, but other downstream tasks such as
stellar classification could also be explored. The architecture of EncoTESS enables its future extension to TESS light curves of all cadences, and additional surveys such as Kepler and the upcoming PLATO mission. The core EncoTESS framework and library of encodings produced for the
stars used in this work are publicly available at https://github.com/philvanlane/encotess.
Read the full abstract ▾
All authors Phil R. Van-Lane, Joshua S. Speagle, Ryan Cloutier, Christopher A. Theissen, Gwendolyn M. Eadie, Ilay Kamai
Cosmology and Nongalactic Astrophysics
Quantifying the systematic impact of differential beam response on the BICEP CMB polarization data from 2016 through 2024
B. D. Elwood, P. A. R. Ade, Z. Ahmed et al. (+83 more)
As
cosmic microwave background (CMB) polarization experiments, including BICEP3, BICEP Array, and future BICEP experiments, achieve ever-deeper polarization maps in search of
primordial B-modes sourced from inflation, constraining instrumental systematics below statistical uncertainties becomes progressively more challenging. Since polarimetry in the BICEP
telescopes is performed by pair-differencing co-located, orthogonally polarized detectors, differential beam response leads to temperature-to-polarization ($T \rightarrow P$) leakage, introducing a potential systematic bias on the inferred tensor-to-scalar ratio $r$. To mitigate this leakage, the lowest-order beam mismatch modes are filtered out of the CMB polarization maps through deprojection; however, residual undeprojected modes remain. To quantify this residual contamination, we perform dedicated in situ far-field beam measurements of the BICEP receivers during austral-summer calibration campaigns. We quantify the systematic impact of the undeprojected residuals with a specialized set of timestream simulations based on the measured per-detector beams. These "beam measurement-informed simulations" yield an estimate of the false polarized signal sourced by the undeprojected residuals. We summarize the beam measurements relevant to the BK24 data release and present preliminary residual-leakage results for BICEP3 at 95 GHz. For BICEP3 over 2016-2024, deprojecting all six standard templates together with readout-crosstalk templates and their radially smoothed counterparts reduces the equivalent-$r$ leakage amplitude from $\rho=(4.5\pm0.7)\times10^{-3}$ to $(1.12\pm0.06)\times10^{-3}$. We further describe an ongoing program to extend the deprojection basis beyond its historical six modes, guided by a forward optical model that relates candidate leakage modes to perturbations of physical instrument parameters.
Read the full abstract ▾
All authors B. D. Elwood, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, V. Buza, B. Cantrall, J. R. Cheshire IV, J. Connors, J. Cornelison, M. Crumrine, A. J. Cukierman, E. Denison, L. Duband, M. A. Echter, M. Eiben, S. Fatigoni, J. P. Filippini, A. Fortes, M. Gao, C. Giannakopoulos, N. Goeckner-Wald, D. C. Goldfinger, S. Gratton, J. A. Grayson, A. Greathouse, P. K. Grimes, M. Halpern, S. Henderson, T. D. Hoang, J. Hubmayr, H. Hui, K. D. Irwin, M. Izquierdo Poza, J. H. Kang, K. S. Karkare, S. Kefeli, J. M. Kovac, C. Kuo, K. Lasko, K. Lau, M. Lautzenhiser, T. Liu, S. C. Mackey, N. Maher, K. G. Megerian, L. Minutolo, L. Moncelsi, Y. Nakato, H. T. Nguyen, R. O'Brient, S. N. Paine, A. Patel, M. A. Petroff, A. R. Polish, T. Prouve, C. Pryke, C. D. Reintsema, T. Romand, M. Salatino, A. Schillaci, B. Schmitt, B. Singari, A. Soliman, T. St. Germaine, A. Steiger, B. Steinbach, R. Sudiwala, K. L. Thompson, C. Tucker, A. D. Turner, C. Vergès, A. G. Vieregg, A. Wandui, A. C. Weber, J. Willmert, W. L. K. Wu, H. Yang, C. Yu, L. Zeng, C. Zhang, S. Zhang
Instrumentation and Methods for Astrophysics
Status of BICEP Array and Integration of the 220/270 GHz Receiver
A. Steiger, P. A. R. Ade, Z. Ahmed et al. (+83 more)
Measurements of the polarization of the
cosmic microwave background are critical for modern cosmology as they constrain the physics of the early universe and
cosmic inflation. BICEP Array is using a series of small-aperture polarimeters located at the South Pole to measure this signal with a projected uncertainty on the tensor-to-scalar ratio r of approximately 0.001 by 2034. The 30/40 GHz receiver and the 150 GHz receiver have been observing the
cosmic microwave background for multiple years, and data from these receivers will be included in the next published BICEP analysis result which includes all data taken through 2024. The 220/270 GHz receiver is partially completed with seven out of twelve detector modules installed, and is planned to be filled with five additional modules prior to the 2027 observation season. Finishing this receiver is a top priority for BA as the science goals of the experiment require the
dust foreground cleaning this receiver will enable. On-site characterization efforts for this receiver from the 2025-26 austral summer show satisfactory spectroscopy, beam pointing, and 220 GHz efficiency, while the 270 GHz efficiency is an active area of work.
Read the full abstract ▾
All authors A. Steiger, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, V. Buza, B. Cantrall, J. R. Cheshire IV, J. Connors, J. Cornelison, M. Crumrine, A. J. Cukierman, E. Denison, L. Duband, M. A. Echter, M. Eiben, B. D. Elwood, S. Fatigoni, J. P. Filippini, A. Fortes, M. Gao, C. Giannakopoulos, N. Goeckner-Wald, D. C. Goldfinger, S. Gratton, J. A. Grayson, A. Greathouse, P. K. Grimes, M. Halpern, S. Henderson, T. D. Hoang, J. Hubmayr, H. Hui, K. D. Irwin, M. Izquierdo Poza, J. H. Kang, K. S. Karkare, S. Kefeli, J. M. Kovac, C. Kuo, K. Lasko, K. Lau, M. Lautzenhiser, G. Liu, S. C. Mackey, N. Maher, K. G. Megerian, L. Minutolo, L. Moncelsi, Y. Nakato, H. T. Nguyen, R. O'Brient, S. N. Paine, A. Patel, M. A. Petroff, A. R. Polish, T. Prouve, C. Pryke, C. D. Reintsema, T. Romand, M. Salatino, A. Schillaci, B. Schmitt, B. Singari, A. Soliman, T. St. Germaine, B. Steinbach, R. Sudiwala, K. L. Thompson, C. Tucker, A. D. Turner, C. Vergès, A. G. Vieregg, A. Wandui, A. C. Weber, J. Willmert, W. L. K. Wu, H. Yang, C. Yu, L. Zeng, C. Zhang, S. Zhang
Instrumentation and Methods for Astrophysics
Optics and broadband anti-reflection coatings for the BA4-90/150 receiver
A. R. Polish, P. A. R. Ade, Z. Ahmed et al. (+84 more)
The BICEP Array
telescopes search for
primordial B-mode polarization from inflationary gravitational waves. This signal is exceedingly faint, demanding excellent map depth and systematics control. The new BA4-90/150 receiver introduces a wide 80-169GHz dichroic band, requiring upgrades throughout the optics chain to reduce loss, reflections, and thermal loading. We developed improved anti-reflection (AR) coatings for our HMPE window, HDPE lenses, and nylon infrared filter, extending our AR technology to span more than an octave of bandwidth. The thermal filtering scheme and several mechanical elements were also updated to further suppress optical loss, reflections, and beam truncation. We aim to build on the proven success of deployed BICEP Array (BA)
telescopes to produce a new small aperture instrument with the lowest optical systematics to date.
Read the full abstract ▾
All authors A. R. Polish, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, V. Buza, B. Cantrall, J. R. Cheshire IV, J. Connors, J. Cornelison, M. Crumrine, A. J. Cukierman, E. Denison, L. Duband, M. A. Echter, M. Eiben, B. D. Elwood, S. Fatigoni, J. P. Filippini, A. Fortes, M. Gao, C. Giannakopoulos, N. Goeckner-Wald, D. C. Goldfinger, S. Gratton, J. A. Grayson, A. Greathouse, P. K. Grimes, M. Halpern, S. Henderson, T. D. Hoang, J. Hubmayr, H. Hui, K. D. Irwin, M. Izquierdo Poza, J. H. Kang, K. S. Karkare, S. Kefeli, J. M. Kovac, C. Kuo, K. Lasko, K. Lau, M. Lautzenhiser, T. Liu, S. C. Mackey, N. Maher, K. G. Megerian, L. Minutolo, L. Moncelsi, Y. Nakato, H. T. Nguyen, R. O'Brient, S. N. Paine, A. Patel, M. A. Petroff, T. Prouve, C. Pryke, C. D. Reintsema, P. J. Rioles, T. Romand, M. Salatino, A. Schillaci, B. Schmitt, B. Singari, A. Soliman, T. St. Germaine, A. Steiger, B. Steinbach, R. Sudiwala, K. L. Thompson, C. Tucker, A. D. Turner, C. Vergès, A. G. Vieregg, A. Wandui, A. C. Weber, J. Willmert, W. L. K. Wu, H. Yang, C. Yu, L. Zeng, C. Zhang, S. Zhang
Instrumentation and Methods for Astrophysics
Advanced Time-Division Multiplexed Readout Chain for the BICEP Array 90/150 GHz Receiver
B. Cantrall, P. A. R. Ade, Z. Ahmed et al. (+89 more)
This work presents the current performance of the advanced time-division multiplexed (TDM) readout chain for the BICEP Array 90/150 GHz receiver. BA4-90/150, scheduled for deployment to the South Pole in 2026–27, will use
photon-noise-limited, feedhorn-coupled transition edge sensor detectors and an upgraded DC SQUID-based TDM system to map the
cosmic microwave background. This new TDM system mitigates readout-induced systematics that are beginning to emerge above the noise floor of the most sensitive maps produced by the BICEP collaboration. Improvements include faster, fully differential SQUID designs, higher TES signal amplification, reduced crosstalk, and hierarchical row-addressing that reduces wiring required for row switching. Measurements made through legacy single-ended warm readout electronics show the upgraded cryogenic readout chain performs as well as or better than the TDM system currently fielded on the BICEP experiment. New warm electronics currently in development at SLAC National Accelerator Laboratory will provide matched fully differential
circuits and higher bandwidth, reducing RF susceptibility and aliased noise contributions. On-sky demonstration of this technology will establish a new low-noise, high-bandwidth TDM architecture for future CMB observatories.
Read the full abstract ▾
All authors B. Cantrall, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, V. Buza, J. R. Cheshire IV, J. Connors, J. Cornelison, M. Crumrine, A. J. Cukierman, E. Denison, W. B. Doriese, L. Duband, M. Durkin, M. A. Echter, M. Eiben, B. D. Elwood, S. Fatigoni, J. P. Filippini, A. Fortes, J. Gard, M. Gao, C. Giannakopoulos, N. Goeckner-Wald, D. C. Goldfinger, S. Gratton, J. A. Grayson, A. Greathouse, P. K. Grimes, G. Haller, M. Halpern, S. Henderson, T. D. Hoang, J. Hubmayr, H. Hui, K. D. Irwin, M. Izquierdo Poza, J. H. Kang, K. S. Karkare, S. Kefeli, J. M. Kovac, C. Kuo, K. Lasko, K. Lau, M. Lautzenhiser, T. Liu, S. C. Mackey, N. Maher, K. G. Megerian, L. Minutolo, L. Moncelsi, Y. Nakato, H. T. Nguyen, R. O'Brient, S. N. Paine, A. Patel, M. A. Petroff, A. R. Polish, T. Prouve, C. Pryke, C. D. Reintsema, T. Romand, M. Salatino, L. Sapozhnikov, A. Schillaci, B. Schmitt, R. Shi, B. Singari, A. Soliman, T. St. Germaine, A. Steiger, B. Steinbach, R. Sudiwala, K. L. Thompson, C. Tucker, A. D. Turner, C. Vergès, A. G. Vieregg, A. Wandui, A. C. Weber, J. Willmert, W. L. K. Wu, H. Yang, C. Yu, L. Zeng, C. Zhang, S. Zhang
Instrumentation and Methods for Astrophysics
Optical characterization of the BICEP array 150 and 220/270GHz CMB polarimeters in the 2026 season
M. Izquierdo Poza, P. A. R. Ade, Z. Ahmed et al. (+83 more)
BICEP Array (BA) is the current-generation instrument in the BICEP series of small-aperture, on-axis refracting
telescopes at the South Pole, designed to constrain the tensor-to-scalar ratio $r$ through degree-scale measurements of B-mode polarization in the
cosmic microwave background (CMB). As BA pushes to deeper sensitivity, control of instrumental systematics, and beam shape mismatch between the co-located orthogonally polarized detectors in particular, has become an increasingly important factor in translating raw sensitivity into a robust constraint on $r$. In these proceedings we report on the 2026 far field beam mapping (FFBM) campaign, which used a thermal chopped source to characterize the BA2 (150~GHz) and BA3 (220/270~GHz) beams. We fit two-dimensional elliptical Gaussians to each detector's beam, derive per-pair differential parameters (differential pointing, beamwidth, and ellipticity). The resulting high-signal-to-noise array-averaged beam maps are used to compute the beam window function $B_l$ for the power spectrum analysis, while the individual per-detector beams feed dedicated beam convolution simulations used to validate the temperature-to-polarization (T$\rightarrow$ P) deprojection procedure. After correcting for the chopper aperture, the recovered beamwidths follow the expected $\lambda/D$ ordering. We also describe two pipeline improvements carried out during the 2026 campaign: an out-and-back jackknife for noise quantification and an elnod-based gain calibration.
Read the full abstract ▾
All authors M. Izquierdo Poza, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, V. Buza, B. Cantrall, J. R. Cheshire IV, J. Connors, J. Cornelison, M. Crumrine, A. J. Cukierman, E. Denison, L. Duband, M. A. Echter, M. Eiben, B. D. Elwood, S. Fatigoni, J. P. Filippini, A. Fortes, M. Gao, C. Giannakopoulos, N. Goeckner-Wald, D. C. Goldfinger, J. A. Grayson, A. Greathouse, P. K. Grimes, M. Halpern, S. Henderson, T. D. Hoang, J. Hubmayr, H. Hui, K. D. Irwin, M. Izquierdo Poza, J. H. Kang, K. S. Karkare, S. Kefeli, J. M. Kovac, C. Kuo, K. Lasko, K. Lau, M. Lautzenhiser, T. Liu, S. C. Mackey, N. Maher, K. G. Megerian, L. Minutolo, L. Moncelsi, Y. Nakato, H. T. Nguyen, R. O'Brient, S. N. Paine, A. Patel, M. A. Petroff, A. R. Polish, T. Prouve, C. Pryke, C. D. Reintsema, T. Romand, M. Salatino, A. Schillaci, B. Schmitt, B. Singari, A. Soliman, T. St. Germaine, A. Steiger, B. Steinbach, R. Sudiwala, K. L. Thompson, C. Tucker, A. D. Turner, C. Vergès, A. G. Vieregg, A. Wandui, A. C. Weber, J. Willmert, W. L. K. Wu, H. Yang, C. Yu, L. Zeng, C. Zhang, S. Zhang
Instrumentation and Detectors
Aliased noise characterization and mitigation in BICEP Array 150, 220 and 270 GHz time-division multiplexed detectors
S. Fatigoni, P. A. R. Ade, Z. Ahmed et al. (+83 more)
Early observations with the BICEP Array 150 GHz (BA2-150) and 220/270 GHz (BA3-220/270) receivers revealed detector noise equivalent temperatures (NETs) higher than expected, together with substantial detector-to-detector and module-to-module scatter. Noise measurements acquired with multiplexing off and high frequency sampling demonstrate that this excess originates from elevated high-frequency detector noise that aliases into the science band during time-division multiplexing. We show that the excess high-frequency noise is correlated with anomalously large logarithmic TES transition slopes, {\alpha}, resulting in elevated electrothermal loop gain and operation near the detector stability boundary. Measurements of {\alpha} indicate values substantially larger than expected, consistent with the sharper superconducting transitions introduced by the inverted TES fabrication process adopted for BA2-150 and BA3-220/270 detectors. Operational mitigation strategies were investigated through both increased multiplexing rates and elevated focal-plane operating temperatures. Faster multiplexing reduces aliasing by shifting the multiplexing Nyquist frequency beyond the excess noise roll-off, while elevated bath temperatures reduce TES electrical power and loop gain, improving detector stability and reducing NET by approximately 10%. These results demonstrate the importance of balancing TES responsivity, electrothermal stability, and multiplexed readout performance in next-generation CMB polarimeters.
Read the full abstract ▾
All authors S. Fatigoni, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, V. Buza, B. Cantrall, J. R. Cheshire IV, J. Connors, J. Cornelison, M. Crumrine, A. J. Cukierman, E. Denison, L. Duband, M. A. Echter, M. Eiben, B. D. Elwood, J. P. Filippini, A. Fortes, M. Gao, C. Giannakopoulos, N. Goeckner-Wald, D. C. Goldfinger, S. Gratton, J. A. Grayson, A. Greathouse, P. K. Grimes, M. Halpern, S. Henderson, T. D. Hoang, J. Hubmayr, H. Hui, K. D. Irwin, M. Izquierdo Poza, J. H. Kang, K. S. Karkare, S. Kefeli, J. M. Kovac, C. Kuo, K. Lasko, K. Lau, M. Lautzenhiser, T. Liu, S. C. Mackey, N. Maher, K. G. Megerian, L. Minutolo, L. Moncelsi, Y. Nakato, H. T. Nguyen, R. O'Brient, S. N. Paine, A. Patel, M. A. Petroff, A. R. Polish, T. Prouve, C. Pryke, C. D. Reintsema, T. Romand, M. Salatino, A. Schillaci, B. Schmitt, B. Singari, A. Soliman, T. St. Germaine, A. Steiger, B. Steinbach, R. Sudiwala, K. L. Thompson, C. Tucker, A. D. Turner, C. Vergès, A. G. Vieregg, A. Wandui, A. C. Weber, J. Willmert, W. L. K. Wu, H. Yang, C. Yu, L. Zeng, C. Zhang, S. Zhang
Quantum Physics
The bottleneck dimension of quantum operations
Pavel Sekatski
Programmable
quantum devices nominally act on a
Hilbert space whose dimension grows exponentially with the number of constituents, but the presence of noise makes it unlikely that they remain coherent across all of this immense
Hilbert space. Then, what is the effective coherent
quantum dimension that should be associated with such imperfect devices? To answer this question we here introduce an operational basis-independent framework which imposes a dimension bottleneck on the programmable transformations. Concretely we ask how strongly the
quantum information they process can be compressed. Formalizing this idea we identify three inequivalent notions, termed $d$-compressibility, $d$-simulability and $d$-embeddability, which differ in the causal structure used to impose the bottleneck and form a strict hierarchy. The framework unifies several existing notions: joint measurability and simulability of
quantum measurements, and the absolute dimensionality of state ensembles, are recovered as special cases. We illustrate the hierarchy with noisy
qubit measurements in complementary bases, and we determine the white-noise thresholds at which the set of all noisy
unitary channels in dimension $n$, a noisy universal
quantum processor, becomes $d$-compressible, $d$-simulable and $d$-embeddable. The thresholds confirm the expectation – maintaining coherence across the full
Hilbert space becomes increasingly demanding as the nominal dimension $n$ increases.
Read the full abstract ▾
Quantum Physics · Cross-listed from math.AG
Kochen-Specker Configurations from Grids on Dual Quadrics
Giuseppe Favacchio
We develop a
geometric framework for constructing and organizing Kochen–Specker configurations in real four-dimensional space. The construction uses finite grids on pairs of smooth quadrics related by Euclidean polarity. Their incidence geometry directly produces orthogonal measurement contexts and parity proofs of
quantum contextuality, yielding infinite families of configurations and a
geometric interpretation and extension of a previously known cyclic construction. For a distinguished subfamily, the same geometry admits a canonical completion determined by secant lines. The first two instances of this completion recover the exceptional root configurations of types $F_4$ and $H_4$, while the smallest case also recovers the Cabello configuration and its
embedding in the Peres configuration. Thus several prominent four-dimensional contextual configurations, previously obtained from different constructions, arise from a single projective-
geometric mechanism.
Read the full abstract ▾
High Energy Physics (Theory)
Remarks on Vafa-Witten theory, or how to sit on a wall
Sergei Alexandrov and Aradhita Chattopadhyaya
We prove three results about refined $SU(N)$ VW invariants on Hirzebruch surfaces. First, we crucially simplify the modular anomaly equation satisfied by the generating series of these invariants by expressing it in terms of complementary generalized error functions, which requires extending these error functions to their singular loci. Second, we evaluate the variation of the modular completions of the generating series upon change of polarization. Finally, a representation of the generating functions in terms of indefinite theta series allows us to compute VW invariants at the walls of marginal stability, and to express them in terms of the invariants on the two sides of the wall and those of lower ranks. All the results exhibit a universal structure suggesting their wider applicability.
Read the full abstract ▾
Quantum Physics
Fluctuation-dissipation structure of quantum geometry
Per Moosavi
Geometry of
quantum states is a fundamental research area with applications ranging from topological materials in condensed matter to variational
algorithms in
quantum information. Due to their relative simplicity, pure states are often studied, while mixed states are generally needed, e.g., to have nonzero temperature. Mixed-state geometry, however, is much more challenging and has so far lacked any structure relating distance and
curvature, like the Kähler structure does for pure states. This work introduces that structure. We show that it has the physical meaning of fluctuation-dissipation—by identifying distance with fluctuations and
curvature with linear response—and that it becomes the known structure for pure states, but is non-Kähler otherwise. This paints a simple picture that unifies fluctuation-dissipation and geometry of
quantum states. It also applies on parameter spaces, as encountered in condensed matter or estimation theory. Our picture implies that the geometry contains all linear responses and fluctuations, proves the fluctuation-dissipation relation, explains that
quantum geometry appears in any sum rule, and allows one to geometrically characterize generic transport behaviors. Closed and open systems are treated with equal ease.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Slowly Rolling on a Quantum Correction
Ido Ben-Dayan, Ayushi Srivastava and Amresh Verma
Recent advances in cosmological measurements such as DESI and ACT may indicate an increase in the preferred value of the spectral tilt $n_s$ such that it disfavors rather popular models such as the
Higgs or Starobinski inflation models. We argue that it actually means that the data is now sensitive enough to
quantum corrections beyond simple tree-level models. Resurrecting the old theme of Coleman-Weinberg effective potential, we analyze the predictions of such models, as well as likelihood analysis, leading to a more established and interesting predictive framework.
Read the full abstract ▾
Solar and Stellar Astrophysics
Potsdam Wolf-Rayet stellar atmosphere grids of OB-type stars: I. Spectroscopic temperature diagnostics across metallicity
D. Pauli, H. Todt, W.-R. Hamann et al. (+5 more)
Massive hot
stars are among the major ionizing sources in the Universe. The ionizing flux of a
star strongly depends on its temperature, which is best measured spectroscopically using lines of different ionization stages of the same element. For the quantitative spectral analysis of O-type
stars, helium lines are commonly employed, and for B-type
stars, lines of silicon and magnesium are used. At low
metallicity, many of the diagnostic metal lines disappear. We conduct a systematic theoretical analysis of
stellar atmosphere models of OB
stars to study the effect of
metallicity on key temperature diagnostic lines and how this impacts spectral classification. We computed large grids of state-of-the-art non-LTE
stellar atmosphere models at four different
metallicities, ranging from
solar to 1/31
solar. We presented equivalent widths of selected diagnostic lines in the temperature-
gravity plane and investigated their dependence on
metallicity. Using
Galactic stellar templates of O- and B-type
stars, we established equivalent width ratios for spectral classification and applied them to our models. For the hottest
stars in our model grids, He I lines become detectable at lower
metallicity due to the reduced back-warming in the atmosphere, opening new possibilities for their classification. Metal lines used for the analysis of B-type
stars are mostly absent in the spectra of
stars with
metallicity below that of the Small Magellanic Cloud, except Si lines, challenging current classification schemes. Our
stellar atmosphere grids reveal that the decrease in
metallicity causes many metal lines to disappear, leaving different sensitivities of He I lines the only temperature indicators for B-type
stars in the optical. The ionizing flux of OB-type
stars can be partially trapped within the
stellar wind. As a result, at lower
metallicity, a larger fraction of
stars can emit hard ionizing radiation.
Read the full abstract ▾
All authors D. Pauli, H. Todt, W.-R. Hamann, L. M. Oskinova, A. A. C. Sander, T. Shenar, V. Ramachandran, S. Reyero Serantes
Mesoscale and Nanoscale Physics
Photonic spin-Hall effect as a probe for time-reversal-symmetry broken band topological phases
Deblina Samanta and Darshan G. Joshi
When a plane polarized Gaussian beam of light is incident on a surface, upon reflection it splits into right and left circularly polarized beams that are spatially separated in the direction perpendicular to the plane of incidence. This is known as the photonic
spin-
Hall effect (PSHE). In this work, we show that the centroid shift, which is the intensity weighted average of the shifts of the right and the left circularly polarized beams directly probes the optical
Hall conductivity, which carries the essential information about the topological properties of the system. We show that the centroid shift as a function of the frequency of light has a unique sign structure depending on whether the system is in a time-reversal
symmetry broken band topological phase or a trivial phase. Thus, the PSHE may serve as an unambiguous and a non-invasive probe to detect time-reversal
symmetry broken band topological phases.
Read the full abstract ▾
High Energy Physics (Phenomenology)
Resonant Induced Orbital Electron Capture: Novel method for low-energy $\bar{\nu}_e$ detection
Evgeny Akhmedov, Thierry Lasserre and Leonardo Maturi
We propose a novel approach to detecting low-energy electron antineutrinos based on the induced capture of orbital electrons by
nuclei. This process is resonant, requiring the antineutrino energy to precisely match the energy difference between the final and initial atomic systems. For continuous-spectrum sources, the resonance conditions can be satisfied without fine-tuning, and the effective cross sections depend on the spectral intensity of the $\bar{\nu}_e$ flux at the resonance rather than on the
neutrino energy itself. This opens the possibility of detecting
neutrinos of never previously probed low energies. We identify a number of candidate nuclides that allow transitions to excited states of the daughter
nuclei corresponding to resonant $\bar{\nu}_e$ energies below the inverse $\beta$ decay threshold of 1.8 MeV, and we consider a distinctive atomic-
nuclear coincidence signature for background rejection. We discuss implications of the proposed method for detecting low-energy reactor
neutrinos, geoneutrinos, and keV-scale thermal
solar neutrinos. Applications to
neutrino oscillation experiments and to reactor monitoring are also briefly discussed.
Read the full abstract ▾
High Energy Physics (Theory)
Equivariant Localization for N=2 Theories with Hypermultiplets
Matthias Dennemann and Jan Manschot
Equivariant localization in the $\Omega$-background is a powerful technique for the evaluation of the partition function of $\mathcal{N}=2$ supersymmetric field theory on a toric four-
manifold. For the complex projective plane $\mathbb{CP}^2$, we apply equivariant localization to supersymmetric Yang-Mills theories with gauge groups $SU(2)$ and $SO(3)$ with $N_f$ massive hypermultiplets in the fundamental representation, and the $\mathcal{N}=2^*$ theory with the hypermultiplet in the adjoint representation. We evaluate equivariant correlation functions, which provide an equivariant extension of intersection numbers of
moduli spaces of instantons on $\mathbb{CP}^2$, such as Euler numbers and Segre invariants. In the non-equivariant limit, we compare our results with the evaluation using low energy field theory and integration over the $u$-plane. Using this comparison, we identify a specific overall factor, which captures the difference between a partition function for gauge group $U(2)$ and $SU(2)$ or $SO(3)$ on a compact four-
manifold. We also discuss our results in the context of $S$-duality of the $N_f=4$ and $\mathcal{N}=2^*$ theory, which includes the triality
automorphism group of the
flavor group for $N_f=4$.
Read the full abstract ▾
Solar and Stellar Astrophysics
Magnetic Heating Across the Sun and Solar-like Stars: Universal Scaling Laws from Chromospheres to Coronae
Shin Toriumi, Kosuke Namekata, Yuta Notsu et al. (+2 more)
Magnetic activity in cool
stars governs the thermal structure and high-energy radiative output of their outer atmospheres, thereby influencing
stellar evolution,
stellar winds, and the atmospheres of orbiting (exo)
planets. A long-standing question in
stellar astrophysics is whether the mechanisms responsible for atmospheric heating are universal across the Sun and cool
stars spanning different ages and activity levels. In this paper, we review recent progress in understanding
magnetic heating across the Sun and Sun-like
stars through empirical scaling relations between photospheric
magnetic flux and radiative output from the chromosphere, transition region, and corona. Analysis of more than a decade of Sun-as-a-
star observations reveals that irradiance and
magnetic flux follow power-law relationships over a wide temperature range. While coronal emissions exhibit superlinear scaling with
magnetic flux, chromospheric and transition-region diagnostics show weaker, sublinear dependencies. Remarkably, observations of G-type
stars with ages ranging from 50 Myr to 4.5 Gyr are found to lie on extensions of the
solar scaling laws, suggesting that a common
magnetic-heating mechanism operates across different levels of
stellar activity. We further discuss the application of these scaling relations to reconstructing
stellar X-ray and ultraviolet (XUV) spectra from observed
magnetic fluxes. The resulting synthetic spectra reproduce actual observations of young, active
solar analogs, providing a practical tool to estimate the ionizing radiation whose extreme UV emissions cannot be directly measured.
Read the full abstract ▾
All authors Shin Toriumi, Kosuke Namekata, Yuta Notsu, Mai Yamashita, Vladimir S. Airapetian
Solar and Stellar Astrophysics
Black hole astrometric binaries in the Roman Galactic Bulge Time Domain Survey
Casey Y. Lam, Jessica R. Lu, Kareem El-Badry et al. (+6 more)
The Nancy Grace Roman Space
Telescope (Roman), NASA's next flagship mission, is currently scheduled to launch in August 2026. As part of its mission, Roman will conduct the
Galactic Bulge Time Domain Survey (GBTDS), which will generate $\sim$50,000 epochs of high-precision photometric and astrometric data for $\sim 10^8$ sources across 1.7 deg$^2$ in the
Galactic Bulge. Roman GBTDS astrometry is comparable to
Gaia Data Release 4 in terms of number of
stars, astrometric precision, and time baseline, and is highly complementary in terms of wavelength and sky location. In this paper, we investigate a synthetic population of GBTDS sources to characterize the detectability of unresolved astrometric binaries, in particular those with compact object companions. Assuming the occurrence rate of black holes (BHs) and
neutron stars (NSs) in AU-scale orbits around
stars is $10^{-7}$ and $10^{-6}$, respectively, and that Roman achieves an astrometric precision of $1\%$ of a pixel, $\mathcal{O}(10)$ BH+
star and $\mathcal{O}(10)$ NS+
star detached binaries will be detectable. The BHs will have median mass measurement uncertainties of $\sim 25\%$, increasing the existing sample of detached astrometric BH binaries by a factor of three. Together with the $\mathcal{O}(10^2)$ isolated BHs expected to be discovered by microlensing in the Roman GBTDS and an additional $\mathcal{O}(10)$ detached BH binaries in
Gaia DR4, this will provide a representative view of the quiescent
Galactic stellar-mass BH population.
Read the full abstract ▾
All authors Casey Y. Lam, Jessica R. Lu, Kareem El-Badry, Anil Seth, Joshua D. Simon, Natasha S. Abrams, Andrea Bellini, Matthew W. Hosek Jr., Peter McGill
General Relativity and Quantum Cosmology
Anti-Ultralocality and Plateau Models of Inflation
Joshua Shterenberg, David Garfinkle, Anna I. Rosenzweig et al. (+2 more)
Anti-ultralocality refers to the growth of spatial gradient terms relative to velocity terms in the coupled Einstein–scalar field equations. It is a characteristic feature of decelerated expansion before the onset of inflation. Previous numerical relativity studies have shown that anti-ultralocality prevents the onset of inflation in models with power-law inflaton potentials. In this paper, we show that models with plateau-shaped inflaton potentials, which are considered to be the simplest way to generate a tensor-to-scalar ratio below current observational upper limits, are especially vulnerable to anti-ultralocality effects. The reasons are the flatness of the plateau and the energy density gap of $\sim 10$ orders of magnitude between the Planck density and the plateau potential energy. To study the problem, we develop a protocol for assessing the viability of inflationary models in general, and we apply it to a plateau potential using a previously validated numerical relativity code. We find that, starting from generic initial conditions, the growth of gradient terms in the Einstein equations relative to non-gradient terms either prevents inflation from lasting for enough $e$-folds or triggers a phase of
quantum runaway. We show that the fine-tuning of initial conditions necessary to avoid these issues becomes more severe as the energy scale of inflation is made smaller, disfavoring common approaches for reducing the tensor-to-scalar ratio.
Read the full abstract ▾
All authors Joshua Shterenberg, David Garfinkle, Anna I. Rosenzweig, David Shlivko, Paul J. Steinhardt
High Energy Physics (Theory) · Cross-listed from math.AG
Genus 4 Supermoduli Space Is Not Projected
Ron Donagi and Simone Noja
The supermoduli stack ${\mathfrak M}_g$, parametrizing smooth unpunctured super Riemann surfaces of genus $g$, is known to be non-projected for $g \ge 5$. We extend this result to the even-
spin component of ${\mathfrak M}_4$. This is done by exhibiting an appropriate compact curve in the
spin moduli space ${\mathcal S\mathcal M}_4^{+}$, and computing the restriction to it of the class obstructing the projectedness of ${\mathfrak M}_4^{+}$. This restriction turns out to be non-zero, proving that ${\mathfrak M}_4^{+}$ is non-projected.
Read the full abstract ▾
Strongly Correlated Electrons
Microscopic Modeling of the Charge-Density-Waves in the Rare-Earth Tritellurides
Sijia Zhao, Julian May-Mann, Ian R. Fisher et al. (+1 more)
Despite being arguably the simplest and best characterized quasi-2D charge-density-wave (CDW) systems, the rare-earth tritellurides ($R$Te$_3$) continue to yield surprising experimental results, including recent evidence suggestive of mirror-
symmetry breaking associated with the onset of CDW order. Motivated by this, we consider a 2D electron-
phonon model for a single Te square-net plane, which we analyze using mean-field theory. For an appropriate region of parameter space, we find a finite-temperature continuous transition from the normal state to a unidirectional CDW state with an ordering vector matching that observed experimentally. At lower temperatures, we find a second translation-
symmetry-breaking transition, similar to what occurs in $R$Te$_3$ compounds with heavier rare-earth elements. In certain parameter regimes, we also find an intervening mirror-
symmetry-breaking transition occurring between the two transitions described above. These results reveal an intrinsic susceptibility to mirror-
symmetry breaking in the unidirectional CDW phase, which is relevant to understanding recent experiments on the $R$Te$_3$ compounds.
Read the full abstract ▾
All authors Sijia Zhao, Julian May-Mann, Ian R. Fisher, Steven A. Kivelson
High Energy Physics (Phenomenology)
Low-Frequency Gravitational Bremsstrahlung and Memory in a Medium
Diego Blas, Silvia Gasparotto, Hitoshi Murayama et al. (+2 more)
Gravitational radiation from the early Universe offers a powerful window into physics beyond the Standard Model (SM). In this paper, we investigate the low-frequency tail of gravitational radiation produced by the decay of massive particles. The energy spectrum in Minkowski space-time, $dE/d\omega$, exhibits two distinct regimes: a flat bremsstrahlung/
memory spectrum above a characteristic cutoff frequency and a suppressed quadratic frequency scaling below it. The typical rate of momentum change of the decay products determines the cutoff frequency. We calculate $dE/d\omega$ in two independent but equivalent ways: using Weinberg's soft graviton
theorem and by solving the equations of motion. This further establishes the connection between Weinberg's soft graviton
theorem and the gravitational
memory formula, which we generalize to incorporate the effects of final-state scattering. We then compute the cosmological
stochastic gravitational energy spectrum $h^2\Omega_{\rm h}$ generated by many particle decays in the early Universe. We demonstrate that $h^2\Omega_{\rm h}$ exhibits linear scaling with frequency above the cutoff frequency, transitioning to cubic scaling below it. Our findings reveal a suppression of the low-frequency signal compared to a naive linear extrapolation, with implications for detection prospects. Our results also reveal the connection between bremsstrahlung and
memory in the context of cosmological
stochastic gravitational energy spectra from the early Universe.
Read the full abstract ▾
All authors Diego Blas, Silvia Gasparotto, Hitoshi Murayama, Jan Schütte-Engel, Jann Zosso