Peer Revenue Fully funded

Papers

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

Physics

Watch Physics

Monday 20 July

High Energy Physics (Theory)

Asymptotic behaviour of the derivative expansion in the ERG

Tim R. Morris

We show that the derivative expansion of the exact (functional) renormalization group is a divergent series in any dimension, both for an exponential cutoff and more general smooth cutoffs. We prove this by showing that within massless $\lambda\varphi^4$ perturbation theory, such divergences arise first at two loops. From several lines of theoretical argument and by analysing infinite classes of two- and three-loop contributions, we conclude that the derivative expansion is an asymptotic series that initially converges towards the exact result before divergent behaviour takes over.
Read the full abstract

Strongly Correlated Electrons

Quantum critical fan and emergent relativistic symmetry of two-dimensional Dirac semimetals

Friederike Ihssen, Bilal Hawashin, Mireia Tolosa-Simeón et al. (+1 more)

Two-dimensional Dirac semimetals near a quantum critical point can be described by Gross–Neveu–Yukawa models. In view of recent experimental advances exhibiting a transition from Dirac semimetal to insulator in highly-tunable van-der-Waals heterostructures, a better understanding of finite-temperature effects is mandatory. Here, we study the Gross–Neveu–Yukawa phase diagram of the chiral Ising model with a non-perturbative field-theory approach at zero and finite temperature, both in the semimetallic phase and in the insulating phase with spontaneously broken $\mathbb{Z}_2$ symmetry. At zero temperature, we find a quantum critical point with critical exponents that are close to the ones of the chiral Ising universality class, and show that relativistic symmetry is emergent close to the quantum critical point. At finite temperature, the ordered phase survives up to a finite critical temperature, at which we observe a classical phase transition into the disordered phase. We confirm that this transition lies in the two-dimensional Ising universality class. Finally, we determine the extent and scaling properties of the quantum critical fan, and the behavior of the quasiparticle weight, therein. In summary, we present a unified field-theoretical framework for the phase diagram of the chiral Ising model in the surroundings of its quantum critical point.
Read the full abstract

All authors Friederike Ihssen, Bilal Hawashin, Mireia Tolosa-Simeón, Michael M. Scherer

General Relativity and Quantum Cosmology

Hawking emission of massive vector fields by Kerr black holes

Marco Calzà, Miguel Faria, Yuber F. Perez-Gonzalez et al. (+1 more)

We compute, for the first time, the Hawking emission spectrum of massive vector (Proca) fields by spinning Kerr black holes, determining the associated greybody factors and the resulting mass and spin loss functions. We show, in particular, that the scalar (longitudinal) polarization of the Proca field has a spectrum approaching that of a free scalar field in the massless limit (in which it becomes a pure gauge mode), although we find substantial differences for finite mass. The contribution of the two vector (transverse) polarization modes coincides, as expected, with the one obtained by Page for the Maxwell field in the massless limit. The black hole's evaporation rate is dominated by the scalar mode for slowly spinning black holes and by the two vector modes as the black hole approaches extremality. As for other fields, we find that Proca Hawking emission is Boltzmann-suppressed for Hawking temperatures $T_H\lesssim |\mu-\Omega_H|$, where $\mu$ is the field mass and $\Omega_H$ is the angular velocity of the black hole's horizon. This implies that highly spinning black holes can efficiently emit massive vector fields at temperatures parametrically below the field's mass. Finally, we also find that superradiant emission is more pronounced for massive vector fields, with a maximum amplification factor of $\simeq 7\%$ (compared to $\simeq 4\%$ for massless photons).
Read the full abstract

All authors Marco Calzà, Miguel Faria, Yuber F. Perez-Gonzalez, João G. Rosa

Strongly Correlated Electrons

Non-Fermi-Liquid Behaviors in Weakly Interacting Two-Dimensional Quasicrystals

Junmo Jeon and Shiro Sakai

Non-Fermi-liquid (NFL) behavior is usually associated with strong electronic correlations, quantum criticality, or singular fluctuations that invalidate the quasiparticle picture. Quasicrystals are known to provide a fundamentally different route to such physics: their lack of translational symmetry gives rise to critical single-particle states and fragmented spectra even in the absence of electron-electron interactions. Here, we numerically study the NFL behaviors in quasicrystals with weak interactions. Using Penrose and Ammann–Beenker tilings as representative quasiperiodic systems, we analyze thermodynamic, magnetic, and transport properties within a weak-coupling perturbative framework. The Sommerfeld coefficient and magnetic susceptibility show anomalous temperature dependences governed by the singular energy dependence of the density of states near the Fermi level. The Wilson ratio reveals that low-temperature NFL behavior in quasicrystals is accompanied by enhanced spin fluctuations over a broad range of filling fractions, while its magnitude and temperature dependence vary sensitively with filling fraction. The self-energy shows anomalous scaling and a finite residual scattering rate, indicating the breakdown of quasiparticles. Our site-resolved analysis reveals a pronounced enhancement of the residual scattering rate in regions with a high local density of states. These results serve as a guide to analyze experimental data for quasicrystals and to identify the microscopic mechanism of the NFL behaviors.
Read the full abstract

High Energy Physics (Theory)

The black hole S-matrix in gauge/gravity duality

Emil J. Martinec

A variety of examples of gauge/gravity duality have a Coulomb branch for the gauge theory dynamics. We exploit this feature to construct an S-matrix, in which the initial state is a shell of branes converging on the origin of the Coulomb branch. In the gravitational dual, the shell of branes sources a geometry with a capped throat; the cap descends from the asymptotic region to larger and larger redshift. A trapped surface forms when the redshift of the cap reaches the point where the excitation of strings stretching between the branes is unsuppressed, and the dual gauge theory deconfines. The intermediate state is a long-lived black hole, which then decays via the slow emission of branes back onto the Coulomb branch. We compare and contrast the descriptions of this process in the bulk effective field theory and the dual gauge theory; and discuss the consequences of this construction for the black hole information paradox.
Read the full abstract

Quantum Physics

Calculus of Robinet: completely positive reconstruction of time-averaged diffusive quantum trajectories

Hector Hutin and Antoine Tilloy

Truly continuous quantum trajectories, obtained from homodyne or heterodyne readouts, can only ever be reconstructed approximately. The continuous measurement signal, needed for exact reconstruction, is averaged over bins of finite time $\Delta t$ during any analog to digital conversion step. The best reconstruction possible, knowing only this discrete record, was introduced recently and dubbed the Robinet state. In this article, we show how the Robinet state can be computed with a numerical discretization scheme that is completely positive, accurate to arbitrarily high order in $\Delta t$, and that does not rely on any other external solver. Our derivation relies on a dilation of the stochastic master equation into a system + transmission line setup, constructed in such a way that measuring what we call the "zero mode" of the line yields the Robinet state. We test the method on a challenging example with random Hamiltonian and jump operator, and verify its accuracy up to order $10$. Apart from its numerical interest, our approach provides a wealth of physical insights, extending in particular recent results on purity obtained by Wonglakhon, Chantasri, and Wiseman, that would be difficult to obtain in any other way.
Read the full abstract

Cosmology and Nongalactic Astrophysics

GUEST: Gravitational Universe Exploration with Satellite Tracking. A passive satellite laser-ranging mission for the dark gravitational Universe

Diego Blas, Aurélien Hees, F. Javier Atapuerca et al. (+78 more)

GUEST is a space mission concept whose central objective is the detection of gravitational waves (GWs) in the microhertz band – a physics-rich frequency window that no other present or planned detector can reach at a significant level. The concept is simple: two dense, passive spheres, covered with cube-corner retroreflectors, deployed in {highly eccentric} Earth orbits ($e \gtrsim 0.7$, period $P \gtrsim 33$ h), tracked continuously by the global network of satellite laser-ranging stations over a minimum observation time of 10 years, with an expected total duration of 30 years. The orbits themselves act as resonant detectors of the oscillating gravitational perturbations, with the microhertz sensitivity emerging from the selected orbital parameters. From the same data stream, GUEST delivers a programme of fundamental and applied science that cuts across particle physics, gravitational-wave astronomy, cosmology, astrophysics, and geodesy: the first coherent search for GWs from supermassive black-hole binaries in the $\mu$Hz band, the exploration of primordial GW backgrounds in the unexplored energy-scale gap between pulsar-timing arrays and LISA, a dedicated probe of ultra-light dark matter in a parameter region untouched by any other experiment, a new way to search for ultra-light bosons, order-of-magnitude-improved tests of new gravitational interactions at astronomical ranges, and a step change in the absolute determination of $GM_\oplus$ that underpins the Global Geodetic Observing System and future navigation and Earth-observation missions. This white paper presents the motivation, scientific reach, and mission concept of GUEST.
Read the full abstract

All authors Diego Blas, Aurélien Hees, F. Javier Atapuerca, Giada Bargiacchi, Massimo Bassan, Joshua N. Benabou, Bruno Bertrand, Adrien Bourgoin, Clare Burrage, Nicolò Burzillà, Alfonso Caldiero, Roberto Campagnola, Andrea Caputo, Ana Caramete, Laurentiu Caramete, Joan Manel Casalta Escuer, Julien Chabé, Gabriel Chiritoi, Marco Cinelli, Florin-Ioan Constantin, Neil J. Cornish, Clément Courde, Simone Dell'Agnello, Alessandro Di Marco, Sebastian Ellis, Malcolm Fairbairn, Ariadna Farrés, Joshua W. Foster, Silvia Gasparotto, Marta Goli, Yann Gouttenoire, Michael Häfner, Antonio J. Iovino, Maria-Catalina Isfan, Justin Janquart, Alexander C. Jenkins, Jean-Paul Kneib, Sébastien Le Maistre, David Lucchesi, Marco Lucente, Angus Macdonald, Jorge Martín Camalich, Rosa Martínez Rubiella, Josep J. Masdemont, Ilia Musco, Toshimichi Otsubo, Cristóbal Padilla, Fco. Rogelio Palomo Pinto, Alice Paun, Alice Perego, Roberto Peron, Florentina-Crenguta Pislan, Florin Adrian Popescu, Luca Porcelli, Nanda Rea, Rafael Rebolo, Marco Reyes, Ignasi Ribas, José C. Rodríguez, Pascal Rosenblatt, Albert Roura, Soumen Roy, Mariano Sánchez Nogales, Francesco Santoli, Feliciana Sapio, Anja Schlicht, Ulrich Schreiber, Angela Serrano, Daniel Serrano Lombillo, Alberto Sesana, Carlos F. Sopuerta, Krzysztof Sośnica, Nicola Tamanini, Elisa Todarello, Sokratis Trifinopoulos, Miguel Vanvlasselaer, Dario Vetrano, Massimo Visco, Hanxi Wang, Xiao Xue, Miguel Zumalacárregui

Strongly Correlated Electrons

Exotic Electronic Order in a Parabolic Kagome Semimetal

C. Alexander Baum, Jonas Issing, Sarbajit Mazumdar et al. (+4 more)

We study an interacting kagome-lattice realization of a quadratic band-touching semimetal at 2/3 filling with onsite and nearest-neighbor repulsive interactions. Combining functional renormalization group and slave-boson approaches, we map its phase diagram from intermediate to strong coupling and uncover a hierarchy of unconventional electronic orders. The leading instabilities comprise loop-current order, spontaneous altermagnetism arising from a spin-Pomeranchuk instability, and spin-loop-current order with distinctive and largely unexplored properties. We demonstrate how the interplay of band kinematics, electronic interactions, and quantum geometry governs the selection of these phases. Our findings establish quadratic band-touching semimetals as a promising platform for unconventional symmetry breaking and suggest analogous phenomena in other parabolic semimetals.
Read the full abstract

All authors C. Alexander Baum, Jonas Issing, Sarbajit Mazumdar, Matteo Dürrnagel, Michael Klett, Ronny Thomale, Lennart Klebl

Statistical Mechanics

Information Compression at Criticality

Simon Jiricek, Miroslav Hopjan, Boris Altshuler et al. (+2 more)

Highly excited quantum states at the critical boundary of ergodicity are known to deviate from thermal behavior, yet their dynamical properties remain poorly understood. Here, we uncover the complexity of quantum dynamics at criticality through the lens of intrinsic information compression in energy space. We show that the Hamiltonian spectrum can be systematically truncated, yielding a simplified description of the dynamics while preserving its essential features. Specifically, for both interacting and noninteracting systems, we demonstrate that a vanishing fraction of Hamiltonian eigenlevels suffices to reproduce the power-law decay of the survival probability. The resulting truncated spectrum exhibits a fractal structure characterized by a level-spacing distribution with a power-law tail, while its spectral form factor displays the same asymptotic power-law decay as the survival probability.
Read the full abstract

All authors Simon Jiricek, Miroslav Hopjan, Boris Altshuler, Vladimir Kravtsov, Lev Vidmar

Quantum Physics

Remote entanglement need not be the bottleneck for modular trapped-ion quantum computing

Felix W. Knollmann, David P. Nadlinger, John Blue et al. (+7 more)

Modularity underpins classical computing; as quantum processors encounter limits on fabrication yield, reliability, and size, they will also need it acutely. The bottleneck to linking modules is producing shared entanglement at sufficient rate, density, and fidelity. Trapped ions hold the best demonstrated photonic links, yet they rely on bulky collection optics that cap how densely links can be packed, and remote entanglement operations trail local gates by two orders of magnitude in rate and fidelity. We synthesize several enabling results $\unicode{x2014}$ single-photon heralding, coherent recoil correction, projective distillation, and trap-integrated photonics $\unicode{x2014}$ into one comprehensive architecture that substantially narrows this gap. Single-photon heralding leads to linear scaling of success probability with detection efficiency, allowing compact integrated photonics to saturate the entanglement rate at a local-operation limit in dense, easy-to-parallelize channels. Addressing its inherent error mechanisms at their source, we project a Bell-pair fidelity of 99.9% at rates and densities compatible with fault-tolerant operations. Remote entanglement then need not remain the bottleneck for modular trapped-ion computing; the limit shifts to the local operations that must improve regardless.
Read the full abstract

All authors Felix W. Knollmann, David P. Nadlinger, John Blue, Sabrina M. Corsetti, Sam J. Bishop, Adam R. Martinez, Jelena Notaros, Colin D. Bruzewicz, Robert McConnell, Isaac L. Chuang

Mesoscale and Nanoscale Physics

Fragile Topology is Unstable Under Translation Refinement

Yoonseok Hwang, Saavanth Velury and Taylor L. Hughes

Fragile topological phases become trivial upon the addition of suitable trivial bands, distinguishing them from stable topological phases. Nevertheless, various response phenomena and material realizations have been proposed for fragile phases. At the same time, many of these phenomena can also occur in atomic insulators, leaving open the question of what properties are specific to fragile phases. Enlarging the unit cell offers a natural perspective on this question. Band folding increases the number of bands in a manner analogous to adding trivial bands. In this work, we establish a systematic framework for determining the stability of fragile topology under unit-cell enlargement. We first establish a systematic criterion for trivialization under enlargements compatible with space-group symmetry, grounded in a physical electron-positron picture and formulated through a Hilbert-basis analysis of momentum-space symmetry data. We then show that, for all two-dimensional wallpaper groups, with or without spin-orbit coupling and/or time-reversal symmetry, every symmetry-indicated fragile phase is adiabatically connected to an atomic insulator in a suitable finite supercell and can therefore be trivialized by an arbitrarily small symmetry-preserving perturbation. Our results reveal that fragile topology has only finite stability under translation-symmetry refinement. This highlights that the fate of a fragile phase can depend on translation-symmetry-breaking perturbations, such as charge-density-wave ordering, and suggests that physical signatures insensitive to translation refinement are unlikely to uniquely characterize fragile topology.
Read the full abstract

Astrophysics of Galaxies

Star formation powers optical line emission from the CGM

Huanian Zhang, Lizhi Xie, Zhijie Qu et al. (+9 more)

Using integral field spectroscopy, we explore the disk-halo interface, or the inner circumgalactic medium (CGM), of individual galaxies by constructing and analyzing emission-line maps for a large sample (72) of normal, low-redshift galaxies spanning three orders of magnitude in stellar mass and four orders in star formation rate (SFR). We find a steep turnover occurring at $(1-2) R_e$ in the H$\alpha$, [O {\small II}], and [O {\small III}] line emission radial profiles. Beyond this radius, the slope of the line emission radial profiles becomes shallower as the SFR of the central galaxy decreases, which might reflect the strength of the feedback processes. The line emission fluxes at large radius ($(5-10) R_e$ or $\sim (0.1-0.25)r_{\rm vir}$) correlate with the galaxy's SFR, but not with its stellar mass. These findings suggest that ionizing photons escaping from star-forming regions in the central galaxy account for the observed emission line fluxes from the inner CGM, with escape fractions inferred from the [O {\small III}] and [O {\small II}] ratio. Different state-of-the-art theoretical models do not agree on the predicted dependence of cool gas on the SFR of the central galaxies, highlighting the importance of CGM emission line measurements to distinguish between different subgrid models for star formation and feedback processes.
Read the full abstract

All authors Huanian Zhang, Lizhi Xie, Zhijie Qu, Dennis Zaritsky, Luis C. Ho, Min Bao, Fabio Fontanot, Michaela Hirschmann, Chenxu Liu, Gabriella De Lucia, Enci Wang, Haoyan Zheng

Cosmology and Nongalactic Astrophysics

Bispectrum BAO and the baryon-dark matter relative velocity

Adriana Nadal-Matosas, Héctor Gil-Marín and Licia Verde

We evaluate the Baryon Acoustic Oscillation (BAO) signal in the bispectrum as a tool to detect and characterize the relative velocity effect. We extend the existing framework by presenting an updated model for the redshift-space tree-level bispectrum that comprehensively incorporates all relative velocity terms. We introduce a novel, unbiased technique to extract the isotropic BAO dilation parameter ($\alpha_{\rm iso}$) solely from the bispectrum monopole. Validated against N-body simulations, this template-based extraction successfully recovers the acoustic scale and enhances the statistical constraining power by $\sim30\%$, when analyzed in tandem with the pre-reconstruction power spectrum, offering a powerful complement to standard post-reconstruction pipelines. We quantify how individual relative velocity components distort both two- and three-point statistics. We find that these effects induce distinct systematic shifts in the extracted $\alpha_{\rm iso}$ between the two probes. We find systematic discrepancies of up to $2\%$ for $b_{v^2}=\pm0.05$ and up to $20\%$ for $b_{\delta^{bc}}\le-2$. This differences demonstrate that a direct comparison of independent power spectrum and bispectrum BAO measurements can break parameter degeneracies and isolate the amplitude of these biases. Finally, we provide a concrete prescription to detect and constrain the three associated relative velocity bias parameters, showing that a joint analysis is highly sensitive to the $b_{v^2}$ and $b_{\delta^{bc}}$ amplitudes. This establishes the bispectrum BAO as a robust cosmological probe for current and next-generation galaxy surveys, serving both as a cross-check for standard analyses and a crucial diagnostic tool against systematic biases.
Read the full abstract

Quantum Physics

Adlam's Frame: comment on "Wigner's Frame"

Andrea Di Biagio and Anne-Catherine de la Hamette

Recent no-go theorems based on extended Wigner's Friend scenarios (EWFS) reveal a deep tension between the universal validity of quantum theory and local friendliness (LF), the conjunction of three natural assumptions: the absoluteness of observed events, locality, and no-superdeterminism. In a recent work, Adlam argues that this tension can be dissolved by appealing to quantum reference frames (QRFs). We present and critically assess her proposal. We show that her proposed resolution does not arise from QRFs, but instead relies on three independent modifications: certain degrees of freedom are always definite, observers can flip upon measuring spins, and the outcomes the superobservers record and use to test the inequalities are not their friends' observed results. The proposal and the arguments for the plausibility of these modifications rest on several misconceptions about QRFs and EWFS, which we rectify. We conclude that, within standard quantum theory, quantum reference frames do not evade the EWFS no-go theorems.
Read the full abstract

High Energy Physics (Phenomenology)

Towards the Swampland of Flavour Symmetries

Xiyuan Gao

In this thesis, we demonstrate the predictive power of the flavour models without explicit flavour symmetries, which we call the `swampland of flavour symmetries'. Firstly, we revisit the minimal type II seesaw model, which extends the Standard Model (SM) with a TeV-scale triplet scalar field. We find that certain flavour textures of the neutrino mass matrix can suppress the tightly constrained $\mu\to e$ transition rates and allow a $5-6$ TeV effective cut-off scale, even when the relevant flavour symmetries are all strongly broken. Next, we show two examples in which some SM flavour parameters are calculable, but the underlying symmetries remain implicit. (i) In the most minimal $SO(10)$ theory, although the quark-lepton symmetry does not manifest at low energies, we find that the $b-\tau$ mass ratio can be correctly predicted when the leptoquarks contained in the scalar sector lie at TeV scale, as motivated by the long-standing $B$ anomalies. (ii) We identify a new class of anomaly-free chiral symmetries in the SM (including three right-handed neutrinos), referred to as enhanced $B-L$, under which all neutrinos are massless. In this framework, the neutrino masses are not free parameters but arise solely through the dynamical symmetry breaking effects, known as neutrino condensate. Furthermore, we note that the swampland of flavour symmetries could also involve light new particles, in particular the flavourful axions. As a preliminary study, we calculate an overlooked two-loop contribution to the axion flavour violating interactions in a minimal axion model, and analyze its impact on explaining a recent excess at Belle II.
Read the full abstract

High Energy Physics (Phenomenology)

Gravitational waves from self-resonance during reheating with a quantum-corrected inflaton potential

Tomoya Inada, Noel Jonathan Jobu, Kenji Nishiwaki et al. (+2 more)

We investigate how localized quantum corrections to the inflaton potential affect preheating dynamics and the resulting stochastic gravitational wave (GW) spectrum. When these corrections sufficiently suppress the quadratic term of the potential near its minimum, inflaton self-resonance can produce a peaked GW spectrum. On the other hand, we find that a smooth and enhanced spectrum can appear if the quadratic term acquires a negative coefficient. As a concrete realization, we analyze the $\alpha$-attractor T-model with a one-loop Coleman–Weinberg correction induced by a heavy scalar and compute the resulting GW spectra using lattice simulations. The GW signals lie in the ultra-high-frequency regime at frequencies above the kHz range. These results suggest that GW signals from preheating may probe quantum corrections to the inflaton potential, thereby providing indirect information about the underlying UV physics.
Read the full abstract

All authors Tomoya Inada, Noel Jonathan Jobu, Kenji Nishiwaki, Toshifumi Noumi, Naoki Yamatsu

High Energy Physics (Phenomenology)

Fate of Metastable Vacua in the Type-II Two-Higgs Doublet Model

Debtosh Chowdhury, Kirtimaan A. Mohan, Poulami Mondal et al. (+1 more)

The scalar potential of the Two-Higgs-Doublet Model (2HDM) can admit multiple non-degenerate vacua due to the presence of the two Higgs doublets unlike the Standard Model (SM). For a physically viable parameter point, one of these vacua must correspond to the physical electroweak (EW) symmetry breaking vacuum with the vacuum expectation value of about $246$ GeV. Given the complex structure of the scalar potential, the physical EW vacuum may be metastable in nature rather than the global minimum of the potential. In this work, we delineate regions of the parameter space in the Type-II 2HDM accommodating multiple extrema of the scalar potential and analyze, in a gauge-independent manner, the stability of the EW vacuum there at the tree level and beyond. A Bayesian global fit of the Type-II 2HDM, including next-to-leading-order unitarity constraints and the latest experimental measurements, indicates that parameter space regions leading to metastable EW vacua are excluded at both the tree and one-loop levels.
Read the full abstract

All authors Debtosh Chowdhury, Kirtimaan A. Mohan, Poulami Mondal, Subrata Samanta

Mathematical Physics

A converse to generalized Runcorn's theorem

Vjekoslav Kovač and Ivica Smolić

We study an inverse problem for generalized Runcorn's theorem motivated by an apparent paradox of lunar magnetism. In mathematical terms, we characterize square-integrable complex functions $f$ such that $$ \int_{\{ x\in\mathbb{R}^n : a \leq |x| \leq b \}} f(x) \nabla u(x)\cdot\nabla v(x)\,\mathrm{d}\mathrm{V}(x) = 0 $$ for every complex harmonic function $u$ in the inner ball $|x|<r_+$ and every complex harmonic function $v$ in the exterior region $|x|>r_-$ that vanishes at infinity. The solution space depends on whether the radii $a$ and $b$ such that $r_-<a<b<r_+$ are regarded as varying or fixed. The solutions are described through the expansion of $f$ into spherical harmonics, and explicit representations are provided.
Read the full abstract

Cosmology and Nongalactic Astrophysics

Probing large mass-splitting inelastic Dark Matter with RES-NOVA

D. Alloni, G. Benato, P. Carniti et al. (+46 more)

Probing inelastic dark matter at large mass splittings requires heavy target nuclei, an extended recoil-energy range, and the high-velocity tail of the dark-matter distribution. We exploit these features with the RES-NOVA prototype detector, featuring a PbWO4 cryogenic calorimeter, produced from archaeological Pb and operated at the deep-underground laboratory of Gran Sasso of INFN (Italy), analyzing a 32.4 g day exposure over 2.5 keV - 1 MeV under both the Standard Halo Model (SHM) and a Large Magellanic Cloud (LMC)-motivated velocity distribution. We extend direct-detection constraints beyond the 330 keV reach of established technologies (e.g. Xe-based TPCs), probing splittings up to 510 (780) keV in the SHM (LMC) benchmark, while future exposures will probe new regions of the parameter space.
Read the full abstract

All authors D. Alloni, G. Benato, P. Carniti, M. Cataldo, L. Chen, M. Clemenza, M. Consonni, G. Croci, I. Dafinei, F.A. Danevich, C. de Vecchi, D. Di Martino, R. Elleboro, N. Ferreiro Iachellini, F. Ferroni, F. Filippini, S. Ghislandi, A. Giachero, L. Gironi, P. Gorla, C. Gotti, D.L. Helis, D.V. Kasperovych, V.V. Kobychev, G. Marcucci, A. Melchiorre, A. Menegolli, S. Nisi, M. Musa, L. Pagnanini, L. Pattavina, G. Pessina, S. Pirro, S. Pozzi, M.C. Prata, A. Puiu, S. Quitadamo, M.P. Riccardi, M. Rossella, R. Rossini, E. Sala, F. Saliu, A. Salvini, V.I. Tretyak, L. Trombetta, D. Trotta, H. Yuan, J. Luengas, H. Ramani

High Energy Physics (Phenomenology)

Factorization of the triple-collinear $q \to qc\bar{c}$ splitting function at first order in opacity

Shahin Iqbal and Urs Achim Wiedemann

In strongly ordered collinear limits, triple-collinear $1\to 3$ splitting functions factorize into products of $1\to 2$ splitting functions. Here, we investigate whether, and under which conditions, this factorization persists in a finite QCD medium. To this end, we reformulate the opacity expansion as a medium-modification of the compact Catani-Grazzini representation of collinear $1\to n$ splitting functions. We compute the fully differential medium-modified triple-collinear $q\to q c\bar{c}$ splitting function to first order in opacity and leading order in $N_c$, and show that it can be expressed as a sum of momentum-shifted vacuum $q\to q c\bar{c}$ splitting functions multiplied by simple interference factors. In vacuum, this splitting function has a single strongly ordered collinear limit, in which the invariant mass of the outgoing $c\bar{c}$ pair is much smaller than all other invariant masses. The medium-modified splitting function instead exhibits three distinct strongly ordered limits, depending on how the relevant invariant masses – multiplied by a boost factor and interpretable as inverse formation times – compare with the medium length. Remarkably, in all three cases the triple-collinear splitting factorizes also in the medium into a tensor product of $q\to qg$ and $g\to c\bar{c}$ splitting functions. In two of these limits, the latter are medium modified to first order in opacity. This first proof shows that factorization extends to medium-modified triple-collinear splitting functions. Lastly, we relate our results to the longstanding problem of overlapping formation times and discuss their implications for jet-quenching parton showers based on medium-modified $1\to 2$ splittings. We also outline further applications of our formalism and note that our results may inform future phenomenological studies of spin (de)correlations in final-state radiation in dense QCD matter.
Read the full abstract

Cosmology and Nongalactic Astrophysics

Dark Energy Bubble as Dynamical Dark Energy: Properties and CMB Constraints

Batia Friedman-Shaw, Matthew C. Johnson and Katherine J. Mack

Recent DESI results are in tension with the constant dark energy density predicted by the $\Lambda$CDM model. If dark energy is associated with the vacuum energy of a scalar field in a metastable state, it will undergo a first-order phase transition through the nucleation of bubbles containing a reduced dark energy density. In this paper, we explore the consequences of this model, where dark energy density varies in both space and time. We model a single bubble spacetime using the Israel junction conditions and derive each of the usual distance measures in this inhomogeneous cosmology. We find that the model predictions of Alcock-Paczynski distortion have features that align strikingly well with the DESI measurements if the dark energy phase transition occurred at roughly a redshift of 1.4 and if the bubble of lower dark energy density has roughly 10$\%$ less dark energy density than the outer cosmology. Despite this feature, we find that the dark energy bubble is heavily constrained by the CMB which excludes the region of parameter space that reproduces the DESI BAO measurements. Still, the peculiar features in the distance measurements of the dark energy bubble cosmology serve as a useful toy model to motivate and inform future work in the currently poorly explored area of spatially varying dynamical dark energy.
Read the full abstract

High Energy Physics (Theory)

Unlocking the Wronskian Tower: A Simplification of the Holomorphic Modular Bootstrap

Arpit Das and Sunil Mukhi

Characters of rational conformal field theories solve modular linear differential equations labelled by their order and the Wronskian index $\ell$. Direct classification of admissible solutions by solving MLDEs becomes increasingly difficult at higher $\ell$ – where movable poles and accessory parameters appear. In this work we introduce differential operators that relate higher-$\ell$ solutions to lower-$\ell$ ones while preserving modular covariance and integrality of the \(q\)-series. In rank two, this generates all allowed Wronskian sectors from the Mathur–Mukhi–Sen equation. In rank three and higher, it reduces the construction of higher-$\ell$ quasi-characters to simpler equations with lower $\ell$. This gives an efficient new route for organising candidate RCFT characters, and more generally quasi-characters, across the Wronskian tower. As an application, we apply our construction to prove a previously conjectured property on the signs of $\ell=2$ quasi-characters in rank 2.
Read the full abstract

Quantum Physics

Nishimori Threshold Estimation for Bayesian Inference and $\mathbb{Z}_q$ Surface Code Decoding

Rohit Mukherjee and Simon Trebst

In quantum error correction, the error threshold provides essential quantitative guidance for the ability to bring about fault-tolerance through decoding the effects of incoherent noise, weak measurement or inference. However, the numerical value of an error threshold is typically only accessible through large-scale numerical simulations of the underlying noise model. Here we introduce an analytical estimate of error thresholds falling into the Nishimori universality class via a Fourier–Walsh projection scheme that maps the critical point of the underlying disorder-free statistical-mechanics model to the Born-disordered Nishimori critical point. Using a minimal replica theory approach, this closed-form estimate is obtained from a projection of the exact replicated single-bond weight which we find to reproduce (within a percentage point) the known numerical thresholds of random-bond and random-plaquette Ising models / $\mathbb Z_2$ stabilizer codes in spatial dimensions $d=2-5$, and extends to Potts variables with $q\le4$. The main application of our projection scheme is to $\mathbb Z_q$ surface codes, whose decoding problem maps to the disordered $q$-state clock model. For $q\ge5$ the clean clock model has two Berezinskii–Kosterlitz–Thouless transitions, which the projection maps to two Nishimori temperatures that bound an intermediate information-critical phase. The resulting threshold values not only accurately agree with recent decohered-$\mathbb Z_q$-toric-code numerics, but are found to satisfy the Gilbert–Varshamov self-dual entropy relation $\ln q \simeq H_q(T_1^\ast)+H_q(T_2^\ast),$ although no duality condition is imposed in the construction. Our approach thereby points to a deeper connection between the clean and Born-disordered models, while allowing for instant analytical estimates of error thresholds for a variety of stabilizer codes.
Read the full abstract

High Energy Physics (Phenomenology)

Soft Gluon Wave Function and Evolution Operator in the CGC at Next-to-Leading Order

Ramkumar Radhakrishnan

We construct the soft gluon light cone wave function of a fast moving hadron and the associated unitary evolution operator $\Omega$ up to $\mathcal{O}(g^{2})$ in pure Yang Mills theory $(N_{f} = 0)$, within the Color Glass Condensate (CGC) framework. Working in light cone gauge, we perform a Born Oppenheimer separation between fast valence and soft modes and implement the eikonal approximation, which allows $\Omega$ to be written as a fully normal ordered series in soft gluon creation and annihilation operators. The expansion coefficients are functionals of the non-commuting valence color charge density operators $\rho$. We fix the coefficients by using the unitarity and explicit diagrammatic calculations within light-cone perturbation theory (LCPT). As an application, we diagonalize the pure Yang Mills soft Hamiltonian through orders $g$ and $g^{2}$ and show that the off diagonal mixing elements between Fock sectors cancel leading to the coherent background field energy proportional to $\rho^{2}$.
Read the full abstract

High Energy Physics (Phenomenology)

Probing the Cosmic Axion Background via Axion-Photon Conversion in Filaments

Duncan Rocha, Gordan Krnjaic and Matthew J. Baldwin

The cosmic axion background (CaB) is a hypothetical population of relativistic axions produced in the early universe. If the CaB is produced from dark matter decays, the axions in this population can convert to photons in the magnetic fields of cosmological filaments, resulting in an isotropic gamma ray background flux. We present new indirect detection constraints on the axion mass and axion-photon coupling, for GeV-TeV dark matter with a decay lifetime below $10^{30}$ sec, by comparing this flux against experimental data. We exclude significant parameter space for axion masses below $10^{-5}$~eV for a broad range of dark matter masses and lifetimes, assuming conservative filament magnetic field strengths ($\sim 1$ nG). For large filament fields ($\sim 100$ nG), our strategy also constrains a portion of the QCD-axion parameter space for TeV-scale dark matter masses.
Read the full abstract

Mesoscale and Nanoscale Physics

Probing Synthetic Caroli-de Gennes-Matricon States Through Critical Current in Full-Shell Nanowire Josephson Junctions

Carlos Payá, Ángel Ibabe, Mario Gómez et al. (+6 more)

Full-shell hybrid nanowires consisting of a semiconductor core fully enveloped by a superconducting shell have emerged as a platform to study Caroli-de Gennes-Matricon (CdGM) analogs. These subgap states can be considered a synthetic version of CdGM states in Abrikosov vortices. Unlike conventional CdGM states, these analogs exhibit a level spacing comparable to the superconducting gap, making them readily observable via tunneling spectroscopy techniques. The spectral density of CdGM analogs follows a characteristic skewed pattern as a function of applied axial magnetic field, an effect that is superimposed on the Little-Parks oscillations of the shell's gap induced by fluxoid quantization. Here, we provide experimental evidence for CdGM analogs through a distinctive skewness fingerprint in the critical current and zero-bias resistance of overdamped Josephson junctions based on full-shell nanowires.
Read the full abstract

All authors Carlos Payá, Ángel Ibabe, Mario Gómez, Thomas Kanne, Jesper Nygård, Ramón Aguado, Pablo San-Jose, Eduardo J. H. Lee, Elsa Prada

Earth and Planetary Astrophysics

Late-infall-induced formation of giant planets, multigenerational planetesimals, and disk substructures

Haichen Zhao, Tommy Chi Ho Lau, Joanna Drążkowska et al. (+2 more)

Late infall can replenish the building materials of planets in protoplanetary disks and dramatically alter their structural evolution. The resulting pressure bumps effectively accumulate dust, facilitate grain coagulation, and trigger planetesimal formation via the streaming instability. In this work, we investigated the potential for planetesimal and planet formation, as well as the emergence of observable substructures, in disks undergoing late-stage infall. We utilized a comprehensive modeling framework that couples dust coagulation and dynamics, planetesimal formation, N-body gravity, planetary growth, and planet-disk interactions. Our results show that the abundant dust supply and the migration barrier created by the infalling gas enable the rapid formation of gas giants via pebble and gas accretion within one million years, even at large orbital distances (~70 au). These giants, in turn, exert torques that generate multiple secondary disk substructures, fostering multigenerational planetesimal formation and resulting in diverse planetary system configurations. The planetesimals exhibit distinct dynamical properties that are determined by their formation epoch and environment, which are analogous to the small-body populations in the outer Solar System. Both the infall- and planet-induced substructures are clearly visible in synthetic 1.3-mm continuum observations, closely resembling the multi-ring disks detected in ALMA surveys. Our model provides a new perspective on the origin of distant giant planets, long-lasting planetesimal formation, and the prevalence of disks with multiple substructures.
Read the full abstract

All authors Haichen Zhao, Tommy Chi Ho Lau, Joanna Drążkowska, Tilman Birnstiel, Sebastian M. Stammler

Cosmology and Nongalactic Astrophysics

Dissecting the Scalar Cosmological Collider with the Cosmic Microwave Background

Oliver H. E. Philcox

The cosmological collider program probes ultra-high-energy physics by searching for subtle oscillatory signatures induced by inflationary particle exchange. Due to the non-linear symmetries usually assumed in inflation, these signals do not appear in isolation; moreover, their amplitudes are bounded by perturbativity and unitarity. To comprehensively probe cosmological collider physics, we must jointly analyze the full multi-field inflationary Lagrangian: in this work, we conduct such a study, probing single, double, and triple scalar field exchange and self-interactions across a wide range of masses (in both the complementary and principal series), mixings, and sound-speeds. Using modern theoretical tools (including the cosmological bootstrap and the cosmological flow), we construct a vast library of tree-level primordial bispectra: combining these with recent measurements of the inflationary shape function from Planck and modern sampling techniques, we perform Bayesian exploration of the eight-parameter multi-field likelihood. Most previous studies of cosmological collider physics assume weak mixing, such that the coupling between the scalar field and the Goldstone mode can be treated perturbatively: in our companion study, we demonstrate that this assumption is incompatible with current datasets except at the smallest masses. By solving for the inflationary bispectra numerically using CosmoFlow, we perform the first analysis of the strongly-mixed collider, demonstrating that the Planck constraints are much tighter than the theoretical bounds, though the oscillatory contributions are heavily suppressed. Across the full multi-field landscape, we find no evidence for new physics with a maximal $\chi^2$ improvement of $5.3$.
Read the full abstract

Instrumentation and Methods for Astrophysics

Search for Planetary-mass Black Holes with an Improved Viterbi Algorithm

Raul Rodriguez, George Alestas, Sachiko Kuroyanagi et al. (+1 more)

Primordial black holes in the planetary-mass range have attracted renewed interest; however, the search for gravitational waves from such binaries remains challenging due to their long-lived nature. In this work, we present, define, and validate a fully operational search pipeline developed to detect planetary-mass binaries during their inspiral phase. We use the Viterbi algorithm, a dynamic programming technique that recovers the most likely track based on a Hidden Markov Model. To enhance its performance, we introduce a novel time-frequency representation of the data and a candidate isolation procedure that separates signals from background noise. The evaluation of candidates is carried out using the two detection statistics, $n_{\sigma}$ and NMSE, which quantify the power significance and the consistency with the expected binary evolution. We then validate the search method using O3 LIGO Hanford data with a population of injected signals. The pipeline is able to recover most of the signals with a fixed false-alarm ratio of $3\%$, covering Galactic scales across most of the parameter space and reaching luminosity distances $ \gtrsim 100$ kpc in the most sensitive region. For each candidate, we also obtain an estimate of the system's chirp mass, whose accuracy remains high throughout the detectable range, enabling a rapid characterization of the system upon detection.
Read the full abstract

All authors Raul Rodriguez, George Alestas, Sachiko Kuroyanagi, Juan Garcia-Bellido

Quantum Physics

Probing gravitational interaction between milligram optomechanical oscillators operating in the quantum regime

M. Bonaldi, A. Borrielli, G. Di Giuseppe et al. (+12 more)

We present an ongoing optomechanical experiment aimed at detecting gravitational interaction between milligram-scale oscillators, and exploring its interplay with quantum mechanics. The setup employs two microfabricated oscillators coupled via gravity and read out through a high-finesse optical cavity, at ultra-cryogenic temperature. Finite element simulations, noise modelling, and sensitivity estimates demonstrate that gravitational coupling can be detected with integration times ranging from minutes to hours. The experiment establishes a realistic platform for probing gravitational effects in systems approaching the quantum regime.
Read the full abstract

All authors M. Bonaldi, A. Borrielli, G. Di Giuseppe, N. Malossi, F. Marin, F. Marino, F. Marzioni, R. Natali, G. Novelli, P. Piergentili, A. Pontin, P. Sberna, E. Serra, G. Sordo, D. Vitali