Peer Revenue Returns subject to peer review

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics

Watch Physics

Tuesday 23 June

General Relativity and Quantum Cosmology

When Black Holes Can Wear Pants

Giacomo Cacciapaglia, Manuel Del Piano, Francesco Sannino et al. (+1 more)

We investigate the conditions under which black hole fragmentation, the splitting of a black hole horizon into multiple smaller ones, may occur. The simplest realization is that of a single black hole horizon splitting into two, giving rise to the eponymous pants topology. In classical general relativity, the Bekenstein-Hawking area law forbids such processes for Schwarzschild black holes. For spinning Kerr black holes, purely kinematic analyses impose constraints that prevent fragmentation, even in regimes where entropy considerations might allow it, except possibly in near-extremal cases. We then hunt for scenarios where black holes can wear pants: from the well-known Gregory-Laflamme instability in higher dimensions, to the potential effect of superradiant instabilities in non-axisymmetric radiation trapping, to finally gravitational models that modify the relations between entropy and/or horizon radius and the black hole mass in four dimensions. In all such cases, emission of small fragments can be entropically favored, however its occurrence still depends on the kinematic configuration of the initial state. Our analysis clarifies the theoretical landscape where black holes may fragment, which is particularly relevant for primordial black holes and catastrophic events such as black hole mergers.
Read the full abstract

All authors Giacomo Cacciapaglia, Manuel Del Piano, Francesco Sannino, Vania Vellucci

Optics

Inverse designed photonic crystal waveguides for pulsed operation: dispersion, losses, and controlled light-matter interactions

Dominic Thompson, Stephen Hughes and Nir Rotenberg

Photonic crystal waveguides (PCWs) are a powerful platform for optical technologies because they can spatially confine light on sub-wavelength scales and manipulate the group velocity of propagation modes, both of which enhance light-matter interactions. Many applications in photonics require a large bandwidth of low-loss and constant-velocity slow light, a significant challenge for previous dispersion and Bloch mode engineering techniques. By combining inverse design with an efficient mode solver and physics based formulas, we reduce the computational time of PCW designs by more than 100 times, allowing for the realization of PCWs with up to an order of magnitude increase in bandwidth and up to 4 times decrease in loss. We then explore the trade-offs between bandwidth, disorder-induce loss, group index, and dispersion. As examples, we apply this approach to two active and practical areas of research for PCWs design: broadband, position-tolerant Purcell enhancement, and compact phase shifters for optical communications. Our results significantly improve state-of-the-art PCW designs and provide a general method to optimize PCWs integrated technologies.
Read the full abstract

Astrophysics of Galaxies

Weak Lensing with the SKAO: Radio Shear Measurement

Priyamvad Tripathi, Marzia Rivi, Simon Prunet et al. (+2 more)

Cosmic shear measurements have traditionally been dominated by optical surveys, which offer higher resolution, better sensitivity, higher galaxy number density, and wider area coverage than their radio counterparts. With the advent of upcoming radio surveys, particularly those planned with the SKA-Mid, we would reach the high sensitivity and resolution required for weak lensing studies, allowing radio observations to begin competing with optical surveys in this domain. However, radio observations are affected by fundamentally different instrumental and astrophysical systematics, meaning that shape and shear measurement techniques developed for optical surveys cannot be straightforwardly applied. Fully realizing the weak lensing potential of these next generation radio surveys therefore requires the development and validation of methods tailored specifically for radio datasets. In this chapter, we present a simulation pipeline to generate realistic observations of isolated radio galaxies based on the SKA-Mid AA4 array configuration. We apply three recent radio shape measurement techniques: SuperCALS, RadioLensfit, and DeepShape, to assess their performance on these simulations. Our results show that RadioLensfit and DeepShape yield the most accurate shape estimates, although RadioLensfit is significantly more computationally intensive. We also perform shear recovery on simulated data using RadioLensfit and DeepShape, finding multiplicative and additive shear biases of order a few $10^{-2}$ and $10^{-4}$, respectively. Finally, we highlight the challenge of source separation, which will play a critical role in the success of future radio weak lensing analyses.
Read the full abstract

All authors Priyamvad Tripathi, Marzia Rivi, Simon Prunet, Ian Harrison, André Ferrari

High Energy Physics (Phenomenology)

Application of Deep Learning to Jet Charge Discrimination

Meisam Ghasemi Bostanabad and Mojtaba Mohammadi Najafabadi

The Large Hadron Collider (LHC) produces an enormous volume of data in which the identification and characterization of hadronic jets is a central challenge. Determining the electric charge of the parton initiating a light-quark jet; a task known as jet-charge discrimination; is highly valuable for both precision tests of the Standard Model (SM) and searches for physics beyond it. In this work, we benchmark a range of classical and quantum machine-learning models for the task of distinguishing up-quark from anti-up-quark jets in a controlled QCD environment. Among the approaches tested, a Graph Neural Network achieved the best performance, with an AUC of 0.883. Jet-charge tagging of this kind has broad phenomenological applications, from improving measurements of charge asymmetries to enhancing sensitivity in searches for new particles from beyond the SM where quark versus antiquark discrimination is essential. Our study provides a methodological foundation for deploying modern machine-learning techniques in jet-charge analyses at the LHC experiments.
Read the full abstract

Fluid Dynamics

How is the free surface influence transported in turbulent open channel flows?

Yoshiyuki Sakai and Christian Bauer

We investigate how the influence of a free surface is transported in turbulent open channel flow by analysing matched open- and closed-channel direct numerical simulations up to $Re_\mathrm{\tau} \approx 900$ in a domain large enough to accommodate very-large-scale motions (VLSMs). The turbulent kinetic energy (TKE) budget shows that the surface influence is communicated primarily through transport terms. Near the free surface, pressure transport supplies energy towards the interface, whereas turbulent transport and dissipation are reduced; the resulting energy surplus is exported away from the surface predominantly by viscous diffusion. The near-surface budget terms do not exhibit a single universal similarity scaling: viscous diffusion is organised over the near-surface viscous scale $\ell_\mathrm{V}$, dissipation over the Kolmogorov sublayer scale $\ell_\mathrm{K}$, and pressure-related terms require the mixed velocity scale $u_\mathrm{b} u_\mathrm{\tau}^2 /h$. The pressure-strain redistribution further reveals outer-inner coupling: although intense pressure-strain events remain small-scale, their magnitude and directional bias are organised by low-velocity VLSM streaks. The free-surface influence is therefore best understood as a coupled multi-scale process involving local kinematic constraints, Reynolds-number-dependent surface layers, and outer-layer coherent motions.
Read the full abstract

Quantum Physics

Quantum-enabled active matter at the atomic scale

Sabrina Burgardt, Julian Feß, Alexander Guthmann et al. (+8 more)

Active matter comprises particles that extract energy from their local environment and convert it into motion. Although active particles have been miniaturized down to the nanoscale, realizing activity at the fundamentally smaller scale of individual atoms remains an open challenge, where quantum effects become increasingly relevant. Here, we experimentally demonstrate that individual Cs-133 atoms confined in an optical dipole trap extract energy from an ultracold bath of Rb-87 atoms via quantum-mechanical spin interactions and convert it into active motion. We quantitatively reproduce the resulting dynamics using a parameter-free active Langevin model derived from kinetic theory and support it with event-driven Monte Carlo collision simulations. The microscopic origin of activity is identified as quantum spin exchange, which transfers discrete internal spin energy into kinetic motion. Our work establishes a quantum-enabled route to active matter at the fundamental size limit of single atoms and opens perspectives for exploring the interplay of activity, quantum physics, and mesoscopic non-equilibrium thermodynamics.
Read the full abstract

All authors Sabrina Burgardt, Julian Feß, Alexander Guthmann, Silvia Hiebel, Aritra K. Mukhopadhyay, Sangyun Lee, Michael te Vrugt, Benno Liebchen, Hartmut Löwen, Raphael Wittkowski, Artur Widera

Soft Condensed Matter

Dynamics and stability of inertial flexible chains under follower activity

Sattwik Sadhu, Nitin Kriplani and Raghunath Chelakkot

The dynamics of flexible polymers and chains under follower activity is known to produce diverse nonequilibrium states. A prominent feature of such systems is the emergence of periodic motion arising from the coupling between internal activity and chain conformation. Recently, it has been shown that flexible and extensible chains of active particles exhibit rich dynamical patterns in the overdamped limit, where inertia is negligible. Here, we study the complex dynamics of a flexible and extensible chain of active particles under follower activity when inertia is significant. Using numerical simulations, we quantify the chain dynamics as a function of chain length ($N$), segment mass, and activity. To rationalize the numerical results, we develop theoretical descriptions in the limit of short chains ($N=3$) and long chains ($N \gg 1$). In both these limits, we derive approximate expressions for the bond lengths and bond angles along the contour, which show excellent agreement with the numerical results. In addition, for short chains, we derive the stability conditions for a periodic motion as a function of segment mass and activity. For long chains ($N\gg1$) we identify parameter regime in which the circular, periodic solution becomes structurally unstable. Our theoretical and numerical analysis provides insights into the emergence of ordered and periodic behaviour in active chains.
Read the full abstract

General Relativity and Quantum Cosmology

The $\omega$-Effect from a Multimode Squeezed Graviton State

Nick E. Mavromatos and Sarben Sarkar

The $\omega$-effect in entangled neutral-meson systems provides a sensitive probe of CPT violation induced by quantum-gravitational environments. In open quantum systems, interactions with inaccessible gravitational degrees of freedom can render the reduced meson dynamics non-unitary, causing the CPT operator to become ill-defined, even when the underlying microscopic Hamiltonian is CPT invariant. We present a microscopic derivation of the $\omega$-effect arising from a multimode squeezed gravitational environment generated by an axion cloud around a Kerr black hole. Using the Takagi decomposition of the associated complex symmetric squeezing kernel, the graviton field is expressed in terms of independent squeezed supermodes possessing anomalous correlators. These correlators provide a microscopic quantum counterpart of the stochastic fluctuations that appear in earlier D-particle foam descriptions of the $\omega$-effect, replacing phenomenological variances of flavour-changing D-particle recoil by calculable graviton correlation functions. After tracing over the graviton bath, the anomalous correlators and the weak-interactions-induced mixing combine to generate transitions between the antisymmetric and symmetric two-meson sectors. This results in a small exchange-symmetric admixture, parametrised by $\omega$, in the otherwise antisymmetric EPR state. We obtain an explicit expression for $\omega$ in terms of a sum over Takagi supermodes weighted by their squeezing amplitudes and phases together with the weak-interaction flavour-mixing matrix element. The resulting framework suggests that the $\omega$-effect may be a generic signature of non-classical states of gravitational environments, extending beyond the specific axion-cloud scenario considered here. The observability of the $\omega$-effect from other astrophysical and microscopic black-hole sources is discussed.
Read the full abstract

Atomic Physics

Field validation of GNSS-independent positioning enhancement using a wearable ultra-stable quantum magnetometer

Stirling Scholes, Dominic Hunter, Courtney Dyer et al. (+8 more)

Increasing the resilience of positioning systems that currently rely on Global Navigation Satellite System (GNSS) signals can be achieved by incorporating stable and sensitive measurements of the permanent crustal anomalies in the Earth's magnetic field. We have realised this concept using an in-house-developed, wearable, Free-Induction-Decay Optically Pumped Magnetometer (FID-OPM) to carry out precise and stable measurements of the geomagnetic field in a walking trial. We present an end-to-end validation, including qualification of FID-OPM performance, alongside quantification of improvement in accuracy when data from this sensor is added to a dead-reckoning estimation of position. Using our wearable sensor system we achieve a Beckmann-distributed radial positioning error of 2.24 m over a route exceeding 500 m in length and spanning approximately 360 s.
Read the full abstract

All authors Stirling Scholes, Dominic Hunter, Courtney Dyer, Marcin Mrozowski, Allan McWilliam, Phoebe Utting, David Burt, Paul F. Griffin, James McGilligan, Erling Riis, Stuart J. Ingleby

Solar and Stellar Astrophysics

Beyond the Tayler instability: A new global instability of toroidal magnetic fields in stars

Mikhail E. Gusakov, Laura Becerra, Elena M. Kantor et al. (+2 more)

Stellar toroidal magnetic fields are known to be unstable to the Tayler instability. Here we demonstrate the existence of a complementary current-driven instability of essentially arbitrary toroidal-field configurations in stably stratified nonrotating stars with the following properties: (i) in ideal magneto-hydrodynamics, it grows on the Alfvén timescale $\tau_{\rm A}$; (ii) under certain conditions, it may reveal itself by driving shellular differential rotation about an arbitrary axis perpendicular to the magnetic-field symmetry axis; (iii) it is large-scale in the angular directions $\theta$ and $\varphi$, and develops at radial wave-numbers $k \lesssim \mathcal{N}\tau_{\rm A}/R$, where $\mathcal{N}$ is the Brunt-Väisälä frequency and $R$ is the stellar radius. Thus, unlike the Tayler instability, the proposed instability is intrinsically global. Consequently, it may be less susceptible to dissipative suppression than the Tayler instability and can prevail over it in some regimes. This instability may have broad implications for magnetic field generation in stars and could modify scenarios of magnetic field amplification within the Tayler-Spruit dynamo, contributing to models of efficient angular-momentum transport and chemical mixing in stellar interiors.
Read the full abstract

All authors Mikhail E. Gusakov, Laura Becerra, Elena M. Kantor, Andreas Reisenegger, Juan Alejandro Valdivia

Astrophysics of Galaxies · Cross-listed from math.PR

Toeplitz Determinants and Admissible Correlation Intervals

Thomas Erben

For a homogeneous one-dimensional random field, positive semidefiniteness of finite Toeplitz correlation matrices imposes non-trivial constraints on admissible correlation coefficients. The widths of the corresponding admissible intervals are closely related to determinants of principal Toeplitz submatrices. Using the classical Desnanot–Jacobi determinant identity, I derive a simple determinantal representation for the widths of admissible correlation intervals. As an immediate consequence, I recover the product expressions for admissible interval widths previously stated by Schneider & Hartlap (2009). The argument places these relations into the general framework of classical Toeplitz determinant theory.
Read the full abstract

Accelerator Physics

Design criteria for a beam-driven resonant passive transverse deflector for longitudinal beam diagnostics

D. Bazyl, W. Decking, S. Tomin et al. (+1 more)

Conventional radio-frequency (rf) transverse deflecting structures provide high-resolution longitudinal beam diagnostics, but require externally generated high-power rf, waveguide distribution, synchronization and input coupling at the operating frequency. We propose design criteria for a beam-driven resonant passive transverse deflector that does not require an external rf source. A leading drive bunch excites long-range wakefields in an off-axis periodic copper structure and a delayed witness bunch experiences the transverse wake near a zero crossing. The concept is based on the large temporal slope available from high-frequency wake components. A structure designed for installation after the second bunch compressor in the three-bunch-compressor layout of the European XFEL is optimized to place the zero crossing of the drive-bunch-induced transverse wake potential approximately one rf-bucket spacing of the 1.3 GHz linac, behind the drive bunch. The selected geometry produces a multi-mode transverse kick dominated by TM-like modes. We use time-domain wake simulations, frequency-domain decomposition, cell-number scaling, mechanical-tolerance scans, orbit-offset studies and uniform thermal scaling to determine the operating point and its sensitivity. For this geometry, the zero crossing occurs at s0 = 230.6 mm, with a per-cell temporal slope of Scell = 1.186 mV/(pC fs cell). For a compact 1 m structure operated with a 250 pC drive bunch and a 700 MeV witness beam, the estimated temporal resolution is about 33 fs.
Read the full abstract

All authors D. Bazyl, W. Decking, S. Tomin, I. Zagorodnov

Fluid Dynamics

Data-Driven Flux Parameterization for the Atmospheric Boundary Layer

Abed Hammoud, Edriss S. Titi, Mitchell Bushuk et al. (+3 more)

Turbulent fluxes in the atmospheric boundary layer (ABL) govern exchanges of momentum, heat, and mass between the surface and atmosphere, shaping boundary layer structure and influencing weather, climate, and engineering applications. Yet their representation in coarse resolution models remains challenging, particularly under unstable conditions with strongly nonlocal transport and stable conditions with intermittent turbulence. Here, we develop a data driven turbulent flux parameterization in which nondimensional fluxes are represented by a linearized convolution operator acting on nondimensional mean state profiles. We train and evaluate the closure using high resolution large eddy simulations (LES) of idealized flow over homogeneous surfaces spanning multiple stability regimes. Several first order closure variants are constructed from different combinations of mean temperature and velocity profiles to predict heat and momentum fluxes, and the best model is selected by minimizing mean squared error across training and unseen test cases. The resulting parameterization improves predictive skill relative to a standard K-profile closure while retaining an interpretable operator form. Its learned kernels expose the locality and nonlocality of turbulent transport across stability regimes, linking empirical performance to physically inspectable flux–profile relationships. In a posteriori single column simulations, the closure remains stable and produces state profiles that closely match LES, demonstrating its potential as an accurate and transparent ABL flux parameterization.
Read the full abstract

All authors Abed Hammoud, Edriss S. Titi, Mitchell Bushuk, Marc Calaf, Khaled Ghannam, Elie Bou-Zeid

Quantum Physics

Auxiliary Schmidt Rank as a Resource for Photonic Bell Measurements

Pradip Laha and Peter van Loock

In quantum communication and fusion-based quantum computation, photonic Bell measurements are fundamentally limited when only passive linear optics is employed. While for qubits, some Bell states can be unambiguously identified with static beam splitters and no extra photons or entanglement, additional auxiliary photons or at least additional auxiliary degrees of freedom with a certain level of additional entanglement are needed to approach or attain a complete, deterministic Bell measurement. Here, we prove an exact resource threshold when the same two photons carry system qudits of dimension $d$ and a fixed auxiliary entangled state $\Phi$, possibly distributed over several additional degrees of freedom, with total Schmidt rank $r_\Phi$. We show that a single conclusive Bell-label functional can occur for $r_\Phi\geqslant\lceil d/2\rceil$, but deterministic discrimination of all $d^2$ Bell-state labels requires $r_\Phi\geqslant d$. A maximally entangled rank-$d$ auxiliary state achieves the bound by local Bell-basis sorting between each photon's system and auxiliary degrees of freedom. Thus, the auxiliary Schmidt rank is a certified resource for ancilla-photon-free, embedded photonic Bell measurements.
Read the full abstract

Accelerator Physics

Compilation of lessons learned from ESS cryomodule and benchmarking with projects in implementation phase

N. Elias, K. Canderan, V. Parma et al. (+9 more)

This document presents a deliverable of the project Innovate for Sustainable Accelerating Systems (iSAS), funded by the EU under its program HORIZON-INFRA-2023-TECH-01 via grant agreement n{\deg}101131435 (deliverable D16, WP5). It contains an analysis on elliptical cryomodules developed for the European Spallation Source (ESS) and a benchmark of high-beta cryomodules across six leading international facilities.
Read the full abstract

All authors N. Elias, K. Canderan, V. Parma, P. Pierini, H. Przibliski, E. Simpson, M. Skiba, M. Baylac, J. D Hondt, J. Knobloch, C. Pira, A. Stocchi

Solar and Stellar Astrophysics

Evolution of Stars During the Main Sequence and the Transition to the Red Giant Phase

Ravid Achituv and reem sari

We derive a simple analytical description for the structure and evolution of $3$–$10 M_\odot$ stars throughout main-sequence hydrogen burning. We obtain an analytical relation for the convective core mass, $\frac{M_\star}{M_c}=1+2.1\left(\frac{\mu_c}{\mu_e}\right)^2$, where $\mu$ is the mean molecular weight of the core and envelope. Using this relation, we analytically derive the hydrogen abundance profile outside the convective core. We find that $\mu(m)\propto m^{-0.7}$, and show that this profile is important for an analytical description of these stars. Within this region of variable $\mu$, the temperature, density, and pressure are well approximated by power laws of radius. We derive analytical expressions for the core and stellar radii, stellar luminosity, and effective temperature as functions of $\mu_c$. We provide a simple physical explanation for the main-sequence hook, defined by the minimum in effective temperature. We show that the hook occurs when the hydrogen mass fraction in the core is $x_c\simeq0.045$, and stress that the same convective-core burning physics governs the subsequent evolution. In that sense, at the hook hydrogen is not yet fully exhausted. During late main-sequence evolution, we find that the ratio of nuclear luminosity between the core and the surrounding hydrogen-rich shell is $\simeq4000x_c$. Hence, the main sequence terminates only once $x_c\simeq2.5\times10^{-4}$, when the surrounding layers become as luminous as the core itself and $M_c\simeq0.11 M_\star$. Although this terminal core mass is numerically similar to the Sch"onberg–Chandrasekhar limit, we show that the two are physically unrelated, since the core remains far from isothermal even at this stage. We validate all analytical results using MESA simulations.
Read the full abstract

High Energy Physics (Phenomenology)

Analytic electromagnetic signatures of compact pentaquark structure: A multi-current QCD light-cone sum rules analysis of the $P_{\psi s}^{\Lambda}$ states

Ulaş Özdem

Probing the internal organization of hidden-charm pentaquarks – including the spin-color correlations that distinguish compact diquark-diquark-antiquark configurations from loosely bound hadronic molecules – requires observables beyond mass spectroscopy. We argue that multi-current QCD light-cone sum rules (LCSR) provide a diagnostic framework through exact analytic relations among flavor-sector contributions enforced by the algebra of the interpolating currents. We identify two such signatures: (i) the light-quark contributions satisfy $\mu_{u}/\mu_{d}=e_{u}/e_{d}=-2$ in all four currents considered, reflecting a common Lorentz-color kernel; and (ii) for the $J_{3}(x)$ current the charm contribution vanishes identically, $\mu_{c}=0$, from the Dirac structure of the anti-charm coupling rather than the pseudoscalar charm-diquark embedding alone. Using four diquark-diquark-antiquark currents $J_{1}(x)$-$J_{4}(x)$ with $J^{P}=\tfrac{1}{2}^{-}$, we obtain $\mu_{J_{1}}=-1.35^{+0.35}_{-0.28}\,\mu_{N}$, $\mu_{J_{2}}=3.14^{+0.65}_{-0.50}\,\mu_{N}$, $\mu_{J_{3}}=1.01^{+0.25}_{-0.20}\,\mu_{N}$, $\mu_{J_{4}}=-1.79^{+0.41}_{-0.34}\,\mu_{N}$. These predictions are paired with the $P_{\psi s}^{\Lambda}(4338)$ and $P_{\psi s}^{\Lambda}(4459)$ on mass grounds as a working hypothesis, since the $\pm 0.11~\text{GeV}$ uncertainties accommodate either state within $1\sigma$ of all four currents. The magnitudes $|\mu|\sim 1$-$3\,\mu_{N}$ lie above quark-model and heavy pentaquark chiral perturbation theory expectations ($|\mu|\lesssim 0.5\,\mu_{N}$). Applying the same procedure to two previous molecular LCSR analyses yields $\mu_{u}/\mu_{d}=-1/2$ rather than $-2$, providing an LCSR-internal contrast at the flavor-decomposed level even when total magnitudes are comparable. The two signatures are immune to the state-to-current pairing and offer falsifiable tests of the compact picture.
Read the full abstract

Physics Education

Simulated Gravitational Lensing in the Undergraduate Lab

Daniel FitzGreen

This paper presents a method for fabricating acrylic lenses that simulate the gravitational deflection of light. The fabricated lenses reproduce key features of strong gravitational lensing, while the simulation is further extended to the weak- and microlensing regimes with images analogous to modern astronomical observations. The simulated mass of the lens is measured from the quantitative analysis of the lensed images in each gravitational lensing regime. These independently measured masses are mutually consistent and agree with the values predicted from the machined lens curvature.
Read the full abstract

Quantum Gases

Quantum droplets and condensates in an optical lattice coupled to a dissipative cavity: Collective excitations and non-equilibrium dynamics

G. Vivek, Sudip Sinha and Subhasis Sinha

Motivated by recent experiments on light-matter interacting systems, we investigate a dilute Bose gas and self-bound quantum droplets in a one-dimensional optical lattice coupled to a lossy cavity mode. Using a classical-field approach, we determine the stationary states and collective excitations of this non-equilibrium system. Apart from the usual Bogoliubov modes, we identify a polariton-like gapped excitation, the frequency of which softens as a precursor of the density ordering transition. Moreover, its relaxation time diverges as the critical point is approached, signaling the non-equilibrium nature of this transition. Dynamically, this polariton-like mode can be probed by inducing cavity field fluctuations, which in turn generates spatio-temporal oscillations of both the condensate and droplet states. In the droplet regime, we also analyze the bound modes which bear the characteristics of such non-equilibrium self-bound state. In addition, we uncover solitonic non-equilibrium states, including condensate with kink-like configuration and double-droplet state, and investigate their robustness following a sudden quench. Remarkably, although these states become unstable beyond a critical coupling, they continue to manifest in the dynamics, akin to the scarring phenomena. Our results demonstrate that dissipative cavity coupling provides a versatile route for exploring rich non-equilibrium dynamics of condensates and quantum droplets within experimentally accessible settings.
Read the full abstract

High Energy Physics (Experiment)

First evidence of $X(3872)\to\pi^0\chi_{c0}(1P)$ and search for $X(3915)\to\pi^0\chi_{c1}(1P)$

Belle, Belle II Collaborations: M. Abumusabh, I. Adachi et al. (+410 more)

We search for the pionic transitions $X(3872)\to\pi^0\chi_{cJ}(1P)$ $(J = 0,~1,~2)$ and $X(3915)\to\pi^0\chi_{c1}$ in $B^+\to \pi^0\chi_{cJ}K^+$ decays using the Belle and Belle~II data samples collected at the $\Upsilon(4S)$ resonance, corresponding to integrated luminosities of $711~\mathrm{fb}^{-1}$ and $492~\mathrm{fb}^{-1}$, respectively. We report the first evidence for the decay $X(3872)\to\pi^0\chi_{c0}$ with a significance of $3.4\sigma$, including systematic uncertainties. We measure the product of branching fractions ${\cal B}(B^+\to X(3872)K^+)\times{\cal B}(X(3872)\to\pi^0\chi_{c0})=(20.0\pm6.8\pm2.3)\times10^{-6}$ and the branching fraction ratio ${\cal B}(X(3872)\to\pi^0\chi_{c0})/{\cal B}(X(3872)\to\pi^+\pi^-J/\psi)=2.3\pm0.8\pm0.4$, where the first and second uncertainties are statistical and systematic, respectively. The upper limits at 90% credibility on the products of branching fractions for the $\pi^0\chi_{c1}$ and $\pi^0\chi_{c2}$ modes are $7.5\times10^{-6}$ and $15.3\times10^{-6}$, respectively. The corresponding upper limits on the branching fraction ratios relative to the $\pi^+\pi^-J/\psi$ decay are $0.9$ and $1.8$. The measured branching fractions for $X(3872)\to\pi^0\chi_{cJ}$ are consistent with several theoretical predictions based on the hadronic molecular interpretation of the $X(3872)$. No significant signal is seen for the $X(3915)\to\pi^0\chi_{c1}$ decay, and we set the 90% credibility upper limit of ${\cal B}(B^+\to X(3915)K^+)\times{\cal B}(X(3915)\to\pi^0\chi_{c1})<6.6\times10^{-6}$, while the decays for $J=0$ and 2 are forbidden by parity conservation.
Read the full abstract

All authors Belle, Belle II Collaborations: M. Abumusabh, I. Adachi, A. Aggarwal, H. Ahmed, Y. Ahn, H. Aihara, M. Akdag, N. Akopov, S. Alghamdi, M. Alhakami, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, K. Arai, H. Atmacan, T. Aushev, V. Aushev, R. Ayad, V. Babu, H. Bae, N. K. Baghel, S. Bahinipati, P. Bambade, Sw. Banerjee, M. Barrett, M. Bartl, J. Baudot, A. Beaubien, F. Becherer, J. Becker, G. F. Benfratello, J. V. Bennett, F. U. Bernlochner, V. Bertacchi, M. Bertemes, E. Bertholet, M. Bessner, S. Bettarini, V. Bhardwaj, B. Bhuyan, F. Bianchi, T. Bilka, D. Biswas, D. Bodrov, G. Bonvicini, A. Boschetti, A. Bozek, M. Bračko, P. Branchini, R. A. Briere, T. E. Browder, A. Budano, S. Bussino, F. Callet, Q. Campagna, M. Campajola, M. Carminati, G. Casarosa, C. Cecchi, P. Cheema, C. Chen, L. Chen, B. G. Cheon, C. Cheshta, H. Chetri, K. Chilikin, K. Chirapatpimol, H.-E. Cho, K. Cho, S.-J. Cho, S.-K. Choi, S. Choudhury, S. Chutia, J. Cochran, J. A. Colorado-Caicedo, I. Consigny, L. Corona, S. Cuccuini, J. X. Cui, E. De La Cruz-Burelo, S. A. De La Motte, G. De Nardo, G. De Pietro, R. de Sangro, M. Destefanis, S. Dey, R. Dhayal, A. Di Canto, J. Dingfelder, Z. Doležal, X. Dong, M. Dorigo, G. Dujany, P. Ecker, J. Eppelt, R. Farkas, P. Feichtinger, T. Ferber, T. Fillinger, C. Finck, G. Finocchiaro, F. Forti, A. Frey, B. G. Fulsom, A. Gabrielli, P. Gagneja, E. Ganiev, R. Garg, A. Garmash, G. Gaudino, V. Gaur, V. Gautam, A. Gaz, A. Gellrich, G. Ghevondyan, D. Ghosh, H. Ghumaryan, R. Giordano, A. Giri, P. Gironella Gironell, B. Gobbo, R. Godang, O. Gogota, W. Gradl, E. Graziani, D. Greenwald, K. Gudkova, Y. Han, K. Hayasaka, H. Hayashii, S. Hazra, C. Hearty, M. T. Hedges, A. Heidelbach, G. Heine, I. Heredia de la Cruz, T. Higuchi, M. Hoek, M. Hohmann, R. Hoppe, P. Horak, X. T. Hou, C.-L. Hsu, T. Humair, T. Iijima, K. Inami, N. Ipsita, A. Ishikawa, R. Itoh, M. Iwasaki, P. Jackson, D. Jacobi, W. W. Jacobs, E.-J. Jang, S. Jia, Y. Jin, A. Johnson, K. K. Joo, H. Kakuno, K. H. Kang, G. Karyan, T. Kawasaki, F. Keil, C. Ketter, C. Kiesling, C. Kim, D. Y. Kim, H. Kim, J.-Y. Kim, K.-H. Kim, H. Kindo, K. Kinoshita, P. Kodyš, T. Koga, S. Kohani, A. Korobov, S. Korpar, E. Kovalenko, R. Kowalewski, P. Križan, P. Krokovny, T. Kuhr, Y. Kulii, R. Kumar, K. Kumara, T. Kunigo, S. Kurokawa, A. Kuzmin, Y.-J. Kwon, S. Lacaprara, Y.-T. Lai, T. Lam, J. S. Lange, T. S. Lau, R. Leboucher, H. Lee, M. J. Lee, P. Leo, P. M. Lewis, C. Li, L. K. Li, Q. M. Li, S. X. Li, W. Z. Li, Y. Li, Y. B. Li, Y. P. Liao, J. Libby, J. Lin, Z. Liptak, V. Lisovskyi, C. Liu, G. Liu, M. H. Liu, Q. Y. Liu, D. Liventsev, S. Longo, A. Lozar, T. Lueck, C. Lyu, J. L. Ma, Y. Ma, M. Maggiora, S. P. Maharana, R. Maiti, G. Mancinelli, R. Manfredi, E. Manoni, M. Mantovano, D. Marcantonio, S. Marcello, M. Marfoli, C. Marinas, C. Martellini, A. Martens, T. Martinov, L. Massaccesi, M. Masuda, T. Matsuda, D. Matvienko, S. K. Maurya, M. Maushart, J. A. McKenna, Z. Mediankin Gruberová, R. Mehta, F. Meier, D. Meleshko, M. Merola, C. Miller, M. Mirra, K. Miyabayashi, H. Miyake, R. Mizuk, G. B. Mohanty, S. Moneta, A. L. Moreira de Carvalho, H.-G. Moser, N. Mudgal, Th. Muller, H. Murakami, R. Mussa, K. R. Nakamura, M. Nakao, Y. Nakazawa, Z. Natkaniec, A. Natochii, M. Nayak, M. Neu, S. Nishida, R. Nomaru, S. Ogawa, R. Okubo, H. Ono, Y. Onuki, G. Pakhlova, S. Pardi, J. Park, K. Park, S.-H. Park, A. Passeri, S. Patra, T. K. Pedlar, L. E. Piilonen, P. L. M. Podesta-Lerma, T. Podobnik, L. Polat, A. Prakash, R. pramanik, V. Prasad, C. Praz, S. Prell, E. Prencipe, M. T. Prim, I. Prudiiev, H. Purwar, P. Rados, S. Raiz, K. Ravindran, J. U. Rehman, M. Reif, S. Reiter, M. Remnev, L. Reuter, D. Ricalde Herrmann, I. Ripp-Baudot, S. H. Robertson, J. M. Roney, A. Rostomyan, N. Rout, G. Russo, S. Saha, D. A. Sanders, S. Sandilya, L. Santelj, C. Santos, V. Savinov, B. Scavino, J. Schmitz, S. Schneider, G. Schnell, K. Schoenning, C. Schwanda, Y. Seino, K. Senyo, J. Serrano, C. Sfienti, W. Shan, C. P. Shen, X. D. Shi, T. Shillington, T. Shimasaki, J.-G. Shiu, D. Shtol, B. Shwartz, A. Sibidanov, F. Simon, J. B. Singh, J. Skorupa, A. Soffer, A. Sokolov, E. Solovieva, S. Spataro, K. Špenko, B. Spruck, M. Starič, P. Stavroulakis, S. Stefkova, R. Stroili, M. Sumihama, M. Takahashi, M. Takizawa, U. Tamponi, S. S. Tang, K. Tanida, F. Testa, A. Thaller, D. V. Thanh, T. Tien Manh, O. Tittel, R. Tiwary, E. Torassa, F. F. Trantou, I. Tsaklidis, M. Uchida, I. Ueda, T. Uglov, K. Unger, Y. Unno, K. Uno, S. Uno, Y. Ushiroda, R. van Tonder, K. E. Varvell, M. Veronesi, A. Vinokurova, V. S. Vismaya, L. Vitale, V. Vobbilisetti, R. Volpe, M. Wakai, S. Wallner, M.-Z. Wang, A. Warburton, M. Watanabe, S. Watanuki, C. Wessel, X. P. Xu, B. D. Yabsley, S. Yamada, W. Yan, W. P. Yan, J. Yelton, K. Yi, J. H. Yin, K. Yoshihara, C. Z. Yuan, J. Yuan, L. Yuan, Y. Yusa, L. Zani, F. Zeng, M. Zeyrek, B. Zhang, X. Zhao, V. Zhilich, J. S. Zhou, Q. D. Zhou, X. Y. Zhou, L. Zhu, R. Žlebčík

High Energy Physics (Theory)

Description of curved spacetimes by finite-size matrices in the type IIB matrix model

Keiichiro Hattori, Tatsuya Seko and Asato Tsuchiya

The type IIB matrix model is expected to give a nonperturbative formulation of superstring theory. Its covariant derivative interpretation provides a method to describe curved spacetimes in the model. There, matrices are identified with certain covariant derivatives which can be viewed as infinite-size matrices. Here, by using the Berezin-Toeplitz quantization, we develop a method to regularize these matrices as finite-size ones, which is needed to calculate quantum effects in the interpretation or in particular to apply the interpretation to the results of numerical simulations. As examples, we examine the cases of $T^{2n}$ and $S^2$ in detail.
Read the full abstract

Optics

Color-Center-Compatible Freestanding Diamond Directional Couplers for Quantum Photonics

Colin Sauerzapf, Tom Jäger, Jonathan Enßlin et al. (+6 more)

Freestanding all-diamond color-center photonics is a promising platform for optical integration of spin-based quantum defects. Within this geometry, we realize a key building block for quantum-network interconnects: a directional coupler that acts as an on-chip beam splitter. We design and simulate directional couplers with triangular cross sections using eigenmode and finite-difference time-domain simulations and target near-50:50 splitting at visible wavelengths. We fabricate the devices directly from bulk single-crystal diamond by angled oxygen reactive-ion-beam etching followed by a dry post-release hard-mask removal process. Room-temperature measurements at $\lambda_0\approx 637 \mathrm{nm}$ yield a mean coupling ratio of $C^\mathrm{meas}=46(16) \%$. Finally, we integrate SnV$^{-}$ centers into the nanophotonic structures and observe near-lifetime-limited optical linewidths and coherent optical Rabi oscillations without post-fabrication annealing, identifying the platform as a viable route towards integrated diamond quantum photonics.
Read the full abstract

All authors Colin Sauerzapf, Tom Jäger, Jonathan Enßlin, Oliver von Berg, Vladislav Bushmakin, Roman Kolesov, Rainer Stöhr, Vadim Vorobyov, Jörg Wrachtrup

Instrumentation and Detectors

Anomalously long-delayed afterpulses in large-area photomultipliers

Nikita Ushakov, Bayarto Lubsandorzhiev, Arslan Lukanov et al. (+2 more)

We report the observation of anomalously long-delayed afterpulses in photomultipliers of the Baksan Large Neutrino Telescope project$~-$ 10-inch R7081-100, 8-inch R5912-100, 20-inch R12860 photomultipliers produced by Hamamatsu Photonics, and 20-inch N6205 photomultipliers produced by NNVT. The mean delay times relative to the main pulses are approximately $85~\mu$s, $73~\mu$s, $260~\mu$s, and $90~\mu$s, respectively. The probability of such afterpulses does not exceed 0.1% per photoelectron, and their amplitudes are strictly confined to the single-photoelectron level, regardless of the amplitude of the main pulse. The delay time of these afterpulses shows no significant dependence on the PMT operating voltage.
Read the full abstract

All authors Nikita Ushakov, Bayarto Lubsandorzhiev, Arslan Lukanov, Andrei Sidorenkov, Dmitrii Voronin

Quantum Physics

The Vector and Canonical Components of the Momentum Operator in 3D Euclidean Space Spanned by General Curvilinear Coordinates

M.S.Shikakhwa

We construct the Hermitian vector and canonical components of the momentum operator in 3D Euclidean space spanned by general curvilinear coordinates (GCC's) using a simple, natural and unified approach based on identifying the momentum operator in any coordinate system as mass times the velocity operator. When this latter is calculated by applying the Heisenberg equation of motion, it returns ($-i\hbar$ times) the gradient operator plus an additional zero-valued sum, which when distributed among the components of the gradient, it makes each the Hermitian vector component of the momentum operator in GCC's. The canonical components follow immediately upon symmetrizing each of these vector components in the corresponding base vector. For accessability by wider audiences, we first develop the formalism for the simple polar coordinates and then we develop the case for GCC's.
Read the full abstract

High Energy Physics (Phenomenology)

Universal two-zero texture in SO(10): implications of JUNO and realization from non-invertible symmetries

Zi-Qiang Chen, Wen-Hao Jiang and Ye-Ling Zhou

We apply the universal two-zero texture (UTZT) to all quark and lepton mass matrices in the SO(10) grand unified framework. With charged fermion masses fixed at their best-fit values, this texture contains only seven free parameters to account for nine flavor observables, rendering it highly predictive. Motivated by the recent JUNO indication in favor of the normal ordering of light neutrino masses, we perform an updated analysis of the UTZT in SO(10). The texture remains fully compatible with all current flavor data. The Dirac phase is predicted mainly in two regions, one of which matches very well with current data. A meV-scale $m_{\beta\beta}$ is predicted, beyond the sensitivity bound of future neutrinoless double beta decay measurements. We further explore the origin of the UTZT from non-invertible symmetries, without introducing additional low-energy degrees of freedom. We show that the UTZT can be realized through non-invertible selection rules arising from the $Z_3$ gauging of $Z_N$, with a minimal realization corresponding to $N=7$.
Read the full abstract

Quantum Gases

Optical spectroscopy of Bose-Einstein condensates at finite temperature

R. M. F. Andersen, L. N. Stokholm, I. Zebergs et al. (+4 more)

We report on optical spectroscopic measurements of ultracold and partially condensed 87Rb gases, which show distinct spectral features due to the thermal and the Bose condensed components in the frequency domain. These features are detected in-situ by using a dark-field configuration with single-photon sensitivity and a frequency-agile laser system. To interpret the observed spectra, we develop a model for light propagation through an inhomogeneous atomic cloud. This model enables the extraction of temperature and atom number, which we benchmark against conventional time-of-flight absorption imaging. The spectroscopically obtained cloud parameters show enhanced sensitivity to small thermal fractions in nearly pure condensates. We further compare the spectroscopy in dark-field and bright-field configurations, demonstrating the superior performance of the former. Our results reveal previously unexplored spectral structure in optically dense ultracold gases and establish spectroscopy as a tool for characterizing ultracold systems at very low temperatures.
Read the full abstract

All authors R. M. F. Andersen, L. N. Stokholm, I. Zebergs, N. R. Neubert, A. S. Chatterley, N. Kjærgaard, J. J. Arlt

Medical Physics · Cross-listed from cs.CV

Multilevel Stochastic Plug-and-Play for Sparse-View CT Reconstruction

Antoine De Paepe, Alexandre Bousse and Dimitris Visvikis

Sparse-view computed tomography (SVCT) reduces radiation exposure and acquisition time, but the limited number of projection views makes the reconstruction problem severely ill-posed and leads to streak artifacts when analytical methods are used. Plug-and-Play (PnP) methods combine data fidelity with learned image priors, while stochastic PnP methods use re-noising to reduce the mismatch between denoiser training inputs and reconstruction iterates. However, these methods often require many iterations, which limits their practical efficiency. In this work, we propose multilevel (ML) Stochastic Plug-and-Play (ML-SPnP), a ML stochastic PnP method for SVCT reconstruction formulated on wavelet multiresolution analysis (MRA) approximation spaces. The method combines coarse-to-fine initialization with a finite sequence of ML corrections using resolution-specific denoisers. Under suitable assumptions, the fine-level iterations following the finite ML phase inherit the convergence guarantees of the underlying stochastic PnP algorithm. Experiments on two CT datasets with 20-50 projection views show that ML-SPnP achieves reconstruction quality comparable to the evaluated stochastic PnP methods, while generally requiring less reconstruction time. These results support ML acceleration as an effective strategy for reducing the computational cost of stochastic PnP reconstruction. The code will be made publicly available at https://github.com/antoinedepaepe/ml-spnp.
Read the full abstract

Atmospheric and Oceanic Physics

An observationally constrained probabilistic trigger for organized deep convection in an NWP ensemble

Mark R. Muetzelfeldt, Robert S. Plant, Hannah M. Christensen et al. (+5 more)

A novel stochastic parametrization scheme representing organized convection is described. The effects of mesoscale convective systems (MCSs) are represented in an observationally constrained manner, by probabilistically triggering an MCS scheme in regions of enhanced environmental total column water vapour. In combination with the probabilistic trigger, patterns with given spatiotemporal scales determine where and when the scheme is active. Our scheme builds on the multiscale coherent structure parametrization (MCSP), which represents the top-heavy heating structure associated with MCSs. The original and new MCSP schemes are tested in a numerical weather prediction (NWP) ensemble. Both MCSP schemes improve the spatiotemporal scales of tropical precipitation compared to a control. When the spread-error relationship of tropical precipitation is analysed, the new scheme successfully boosts spread compared to original MCSP, improving the underdispersion of the ensemble seen with the original MCSP.
Read the full abstract

All authors Mark R. Muetzelfeldt, Robert S. Plant, Hannah M. Christensen, Zhixiao Zhang, Tim Woollings, Alison Stirling, Warren Tennant, Mitch Moncrieff

High Energy Physics (Phenomenology)

Disentangle RG Running Parameters with Medium-Baseline Reactor Experiments

Shao-Feng Ge, João Paulo Pinheiro and Shaoyang Qin

We study how the renormalization group running beta functions of mixing angles and leptonic CP phases affect the slow and fast oscillation modes at JUNO. While the slow mode is modulated by the solar parameters, its amplitude can also be affected by the solar angle beta function $\beta_s$ and its phase by the Majorana CP phase counterpart $\beta_{\rm M1}$. On the other hand, the fast mode also receives corrections from the beta functions of the Dirac CP phase $\delta_D$ and the Majorana CP phase $\delta_{\rm M3}$. Since the fast mode is essentially the one measuring the neutrino mass ordering, the RG running effect can then interfere to deteriorate the sensitivity. Fortunately, the JUNO-TAO near detector can provide supplementary measurements of the RG running parameters to restore the mass ordering sensitivity. Since the rephasing phases $\delta_{\rm M1}$ and $\delta_{\rm M3}$ can be shifted by a vector-like rephasing for Dirac neutrinos, their running is physical only in the Majorana case. In consolidated, the mild preference for a nonzero $\beta_{\rm M1}$ by the current JUNO data thus hints the Majorana nature of neutrinos.
Read the full abstract

Quantum Physics

Electrical-Circuit Simulation of the Uhlmann Phase

Yu-Huan Huang, Yu Wang, Jia-Chen Tang et al. (+2 more)

The Uhlmann phase extends the concept of geometric phases to mixed quantum states through a parallel-transport condition on purification amplitudes, but its experimental realization has so far required sophisticated quantum platforms with carefully engineered auxiliary degrees of freedom. In this work, we reformulate the Uhlmann parallel-transport condition as a linear matrix differential equation and vectorize it to obtain an effective dynamical generator. This generator can be directly mapped onto the admittance matrix of a classical RC circuit, thereby translating the Uhlmann dynamics into the evolution of circuit node voltages. We illustrate the mapping using the equatorial-loop model and, via a rotating-frame transformation followed by a real decomposition, derive a time-independent, real-valued dynamical system suitable for analog implementation. LTspice simulations of the resulting active RC network faithfully reproduce the Uhlmann geometric phase and its topological transition at the critical purity, demonstrating that classical electrical circuits offer a simple and accessible platform for probing mixed-state geometric phases.
Read the full abstract

All authors Yu-Huan Huang, Yu Wang, Jia-Chen Tang, Xu-Yang Hou, Hao Guo