Publications

2025

• Topological Quantum Spin Hall Semimetals with Light
  
  • Le Hur Karyn
  Physical Review B, American Physical Society, 2025, 112 (7), pp.075120. We introduce a quantum spin Hall semimetal or Fermi liquid characterized with a Z2 topological invariant, measurable through circularly polarized light. We propose its engineering through two topological metallic band structures in crystals on the honeycomb lattice, with spin-orbit interaction, realizable through the interplay of a charge or spin density wave substrate and Zeeman effects, in between a quantum spin Hall and a quantum anomalous Hall insulator. These systems show topologically protected helical edge or photo-induced currents. (10.1103/d72s-m3rk)
  DOI : 10.1103/d72s-m3rk
• Accessing Generalized Parton Distributions through 2 to 3 exclusive processes
  
  • Duplančić Goran
  • Nabeebaccus Saad
  • Passek-K. Kornelija
  • Pire Bernard
  • Szymanowski Lech
  • Wallon Samuel
  PoS - Proceedings of Science, SISSA, 2025, DIS2024, pp.228. We review our results on a new class of 2 to 3 exclusive processes, as a probe of both chiral-even and chiral-odd quark GPDs. We consider the exclusive photoproduction of a photon-meson pair, in the kinematics where the pair has a large invariant mass, described in the collinear factorization framework. We cover the whole kinematical range from medium energies in fixed target experiments to very large energies of colliders, by considering the experimental conditions of JLab 12-GeV, COMPASS, future EIC and LHC (in ultra-peripheral collisions) cases. Our analysis covers neutral and charged rho-mesons, as well as charged pions. The case of the rho-meson, depending on its polarization, provides access to either chiral-even or chiral-odd GPDs, at leading twist. We find that the order of magnitude of the obtained cross sections are sufficiently large for a dedicated experimental analysis to be performed, especially at JLab. Furthermore, we compute the linear photon beam polarization asymmetry, which we find to be sizeable, in the case of a longitudinally polarized $\rho$-meson or of a charged pion. These predictions are obtained for both asymptotic distribution amplitude (DA) and holographic DA. (10.22323/1.469.0228)
  DOI : 10.22323/1.469.0228
• Hund flat band in a frustrated spinel oxide
  
  • Oh Dongjin
  • Hampel Alexander
  • Wakefield Joshua P
  • Moen Peter
  • Smit Steef
  • Luo Xiangyu
  • Zonno Marta
  • Gorovikov Sergey
  • Leandersson Mats
  • Polley Craig
  • Kundu Asish K
  • Rajapitamahuni Anil
  • Vescovo Elio
  • Jozwiak Chris
  • Bostwick Aaron
  • Rotenberg Eli
  • Isobe Masahiko
  • Verma Manish
  • Crispino Matteo
  • Grundner Martin
  • Kugler Fabian B
  • Parcollet Olivier
  • Schollwöck Ulrich
  • Takagi Hidenori
  • Damascelli Andrea
  • Sangiovanni Giorgio
  • Checkelsky Joseph G
  • Georges Antoine
  • Comin Riccardo
  Proceedings of the National Academy of Sciences of the United States of America, National Academy of Sciences, 2025, 122 (45), pp.1-9. Electronic flat bands associated with quenched kinetic energy and heavy electron mass have attracted great interest for promoting strong electronic correlations and emergent phenomena such as high-temperature charge fractionalization and superconductivity. Intense experimental and theoretical research has been devoted to establishing the rich non-trivial metallic and heavy fermion phases intertwined with such localized electronic states. Here, we investigate the transition metal oxide spinel LiV2O4, an enigmatic heavy fermion compound lacking localized f orbital states. We use angle-resolved photoemission spectroscopy and dynamical mean field theory to reveal a new kind of correlation-induced flat band with suppressed inter-atomic electron hopping arising from intra-atomic Hund coupling. The appearance of heavy quasiparticles is ascribed to a proximate orbital-selective Mott state characterized by fluctuating local moments as evidenced by complementary magnetotransport measurements. The spectroscopic fingerprints of long-lived quasiparticles and their disappearance with increasing temperature further support the emergence of a high-temperature bad metal state observed in transport data. This work resolves a long-standing puzzle on the origin of heavy fermion behavior and unconventional transport in LiV2O4. Simultaneously, it opens a new path to achieving flat bands through electronic interactions in d-orbital systems with geometrical frustration, potentially enabling the realization of exotic phases of matter such as the fractionalized Fermi liquids. (10.1073/pnas.2518213122)
  DOI : 10.1073/pnas.2518213122
• Testing strong-field QED with the avalanche precursor
  
  • Mironov A.A
  • Bulanov S.S
  • Di Piazza A
  • Grech M
  • Lancia L
  • Meuren S
  • Palastro J
  • Riconda C
  • Rinderknecht H.G
  • Tzeferacos P
  • Gregori G
  Phys.Plasmas, 2025, 32 (9), pp.093302. A two-beam high-power laser facility is essential for the study of one of the most captivating phenomena predicted by strong-field quantum electrodynamics (QED) and yet unobserved experimentally: the avalanche-type cascade. In such a cascade, the energy of intense laser light can be efficiently transformed into high-energy radiation and electron-positron pairs. The future 50-petawatt-scale laser facility NSF OPAL will provide unique opportunities for studying such strong-field QED effects, as it is designed to deliver two ultra-intense, tightly focused laser pulses onto the interaction point. In this work, we investigate the potential of such a facility for studying elementary particle and plasma dynamics deeply in the quantum radiation-dominated regime, and the generation of QED avalanches. With 3D particle-in-cell simulations, we demonstrate that QED avalanche precursors can be reliably triggered under realistic laser parameters and layout (namely, focusing $f/2$, tilted optical axes, and non-ideal co-pointing) with the anticipated capabilities of NSF OPAL. We demonstrate that seed electrons can be efficiently injected into the laser focus by using targets of three types: a gas of heavy atoms, an overcritical plasma, and a thin foil. A strong positron and high-energy photon signal is generated in all cases. The cascade properties can be identified from the final particle distributions, which have a clear directional pattern. At increasing laser field intensity, such distributions provide signatures of the transition, first, to the radiation-dominated interaction regime, and then to a QED avalanche. Our findings can also be used for designing related future experiments. (10.1063/5.0283438)
  DOI : 10.1063/5.0283438
• Direct measurement of Tan's contact in a one-dimensional Lieb-Liniger gas
  
  • Huang Qi
  • Yao Hepeng
  • Chen Xuzong
  • Sanchez-Palencia Laurent
  Sci.Adv., 2025, 11 (40), pp.adv3727. The Tan contact has emerged as a pivotal quantity in characterizing many-body quantum systems, bridging microscopic short-range correlations to thermodynamic behavior. It is defined as the weight of universal $1/k^4$ fall off in momentum distribution tails, which can be measured directly in ultracold gases. So far, however, its direct measurement has been hindered in Bose gases due to interactions strongly affecting the expansion dynamics. Here, we present the first direct measurement of the Tan contact in a strongly-correlated Lieb-Liniger gas. Leveraging the one-dimensional geometry of our system, we implement a two-stage expansion scheme, yielding interaction-immune time-of-flight imaging. Our results show excellent agreement with theoretical predictions from quantum Monte Carlo calculations, which also provides independent thermometry of the experiment. By varying atom number, temperature, and interaction strength, we obtain results consistent with the universal scaling law predicted for the trapped Lieb-Liniger model. Our work paves the way for further characterization of the Lieb-Liniger gas across broad interaction regimes and holds promise for extension to other correlated quantum gases in confined geometries. (10.1126/sciadv.adv3727)
  DOI : 10.1126/sciadv.adv3727
• The Yukawa potential of a non-homogeneous sphere, with new limits on an ultralight boson
  
  • Fayet Pierre
  Physical Review D, American Physical Society, 2025, 112 (9), pp.095018. Extremely weak long-range forces may lead to apparent violations of the Equivalence Principle. The final MICROSCOPE result, leading at 95 % c.l. to $|δ| < 4.5 \times 10^{-15}$ or $6.5 \times 10^{-15}$ for a positive or negative Eötvös parameter $δ$, requires taking into account the spin of the mediator, and the sign of $Δ(Q/A_r)_{\rm{Ti-Pt}}$ ($Q$ denoting the new charge involved). A coupling to $B-L$ or $B$ should verify $|g_{B-L}|<1.1 \times 10^{-25}$ or $|g_{B}| < 8 \times 10^{-25}$, for a spin-1 mediator of mass $m < 10^{-14}$ eV$/c^2$, with slightly different limits of $1.3 \times 10^{-25}$ or $\,6.6 \times 10^{-25}$ in the spin-0 case. The limits increase with $m$, in a way which depends on the density distribution within the Earth. This involves an hyperbolic form factor, expressed through a bilateral Laplace transform as $Φ(x=mR)= \langle\,\sinh mr/mr \,\rangle$, related by analytic continuation to the Earth form factor $Φ(ix)= \langle \,\sin mr/mr \,\rangle $. It may be expressed as $Φ(x) = \frac{3}{x^2}\, (\cosh x - \frac{\sinh x}{x}) \times\, \barρ(x)/ρ_0\,$, where $\barρ(x)$ is an effective density, decreasing from the average $ρ_0$ at $m=0$ down to the density at the periphery. We give general integral or multishell expressions of $Φ(x)$, evaluating it, and $\barρ(x)$, in a simplified 5-shell model. $Φ(x)$ may be expanded as $\, \sum \frac{x^{2n}}{(2n+1)!} \frac{\langle \,r^{2n}\,\rangle}{R^{2n}} \simeq 1 + .0827\ x^2 + .00271 \ x^4 + 4.78 \times 10^{-5}\,x^6 + 5.26\times 10^{-7}\, x^8 +\ ... \ $, absolutely convergent for all $x$ and potentially useful up to $x\approx 5$. The coupling limits increase at large $x$ like $mR \ e^{mz/2}/\sqrt{1+mr}$ ($z=r-R$ being the satellite altitude), getting multiplied by $\simeq 1.9,\ 34$, or $1.2\times 10^9$, for $m = 10^{-13},\ 10^{-12}$ or $10^{-11}$ eV$/c^2$, respectively. (10.1103/17wc-xxjm)
  DOI : 10.1103/17wc-xxjm
• Topological p-wave Superconductors with Disorder and Interactions
  
  • del Pozo Frederick
  • Herviou Loïc
  • Dmytruk Olesia
  • Hur Karyn Le
  Physical Review B, American Physical Society, 2025, 111 (7), pp.075170. interacting and disordered topological phases of coupled Kitaev wires, which may support further realistic applications of Majorana fermions. We develop a variety of analytical, mathematical and numerical methods for one and two-coupled wires, associated with a topological marker accessible from real-space correlation functions on the wire(s). We verify the stability of the topological superconducting phase and quantify disorder effects close to the quantum phase transitions, e.g. through two-point correlation functions or using a renormalization group (RG) analysis of disorder. We show for the first time that the double critical Ising (DCI) phase -- a fractional Majorana liquid characterized by a pair of half central charges and topological numbers -- is stabilized by strong interactions against disorder which respects the inversion symmetry between the wires (ie. parity conservation on each wire). In the presence of an inter-wire hopping term, the DCI phase turns into a protected topological phase with a bulk gap. We study the localization physics developing along the critical line for weaker interactions. (10.1103/PhysRevB.111.075170)
  DOI : 10.1103/PhysRevB.111.075170
• Relativistic energy-momentum tensor distributions in a polarized nucleon
  
  • Won Ho-Yeon
  • Lorcé Cédric
  Physical Review D, American Physical Society, 2025, 111 (9), pp.094021. We study in detail the relativistic distributions of energy, longitudinal momentum, longitudinal energy flux, and longitudinal thrust inside nucleons based on the quantum phase-space formalism. Similar to recent studies on the electromagnetic current, we include the effects of the nucleon polarization and show that the latter are essential for understanding how the Breit frame distributions transform under a longitudinal Lorentz boost. We also explicitly demonstrate that, in the infinite-momentum frame, these distributions allow one to recover not only the ``good'' but also the ``bad'' components of the light-front energy-momentum tensor distributions. (10.1103/PhysRevD.111.094021)
  DOI : 10.1103/PhysRevD.111.094021
• Using net quark number gain to probe the phases of QCD
  
  • Mari Surkau V. Tomas
  • Reinosa Urko
  Journal of Subatomic Particles and Cosmology, Elsevier, 2025, 4, pp.100227. We discuss an observable that probes the content of a QCD medium at finite temperature and chemical potential, the net quark number gain. It is the response of the thermal bath to a static quark or antiquark probe. While insignificant at high temperatures, it reveals the bath’s tendency to form meson-like or baryon-like configurations (depending on the probe and chemical potential) at low temperatures, which would screen the probe’s color charge. The net quark number gain also helps explain how a single quark/antiquark can be added to a supposedly confining medium in the first place: the latter provides the missing quarks/antiquarks to form hadron-like states. We sketch the derivation of this general result for temperatures much smaller than the constituent quark masses and discuss possible further applications to study the various features of the QCD phase diagram. (10.1016/j.jspc.2025.100227)
  DOI : 10.1016/j.jspc.2025.100227
• Ionospheric Conductances at the Giant Planets of the Solar System: A Comparative Study of Ionization Sources and the Impact of Meteoric Ions
  
  • Clément Noé
  • Nakamura Yuki
  • Blanc Michel
  • Wang Yuxian
  • Al Saati Sariah
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2025, 130 (1), pp.e2024JA033061. The dynamics of giant planet magnetospheres is controlled by a complex interplay between their fast rotation, their interaction with the solar wind, and their diverse internal plasma and momentum sources. In the ionosphere, the Hall and Pedersen conductances are two key parameters that regulate the intensity of currents coupling the magnetosphere and the ionosphere, and the rate of angular momentum transfer and power carried by these currents. We perform a comparative study of Hall and Pedersen conductivities and conductances in the four giant planets of our Solar System -Jupiter, Saturn, Uranus and Neptune. We use a generic ionospheric model (restraining the studied ions to H + 3 , CH + 5 , and meteoric ions) to study the dependence of conductances on the structure and composition of these planets' upper atmospheres and on the main ionization sources (photoionization, ionization by precipitating electrons, and meteoroid ablation). After checking that our model reproduces the conclusions of Nakamura et al. ( 2022), https://doi.org/10.1029/2022ja030312 at Jupiter, that is, the contribution of meteoric ions to the height-integrated conductances is non-negligible, we show that this contribution could also be non-negligible at Saturn, Uranus and Neptune, compared with ionization processes caused by precipitating electrons of energies lower than a few keV (typical energies on these planets). However, because of their weaker magnetic field, the conductive layer of these planets is higher than the layer where meteoric ions are mainly produced, limiting their role in magnetosphere-ionosphere coupling. (10.1029/2024ja033061)
  DOI : 10.1029/2024ja033061
• Long time behavior of a degenerate stochastic system modeling the response of a population face to environmental impacts
  
  • Collet Pierre
  • Ecotière Claire
  • Méléard Sylvie
  Electronic Communications in Probability, Institute of Mathematical Statistics (IMS), 2025, 30 (none). We study the asymptotics of a two-dimensional stochastic differential system with a degenerate diffusion matrix. This system describes the dynamics of a population where individuals contribute to the degradation of their environment through two different behaviors. We exploit the almost one-dimensional form of the dynamical system to compute explicitly the Freidlin-Wentzell action functional. That allows to give conditions under which the small noise regime of the invariant measure is concentrated around the equilibrium of the dynamical system having the smallest diffusion coefficient. (10.1214/24-ECP650)
  DOI : 10.1214/24-ECP650
• One-Dimensional Carrollian Fluids III: Global Existence and Weak Continuity in $L^\infty$
  
  • Petropoulos P. Marios
  • Schulz Simon
  • Taujanskas Grigalius
  J.Lond.Math.Soc., 2025, 111 (6), pp.e70186. The Carrollian fluid equations arise as the $c \to 0$ limit of the relativistic fluid equations and have recently experienced a surge of activity in the flat-space holography community. However, the rigorous mathematical well-posedness theory for these equations does not appear to have been previously studied. This paper is the third in a series in which we initiate the systematic analysis of the Carrollian fluid equations. In the present work we prove the global-in-time existence of bounded entropy solutions to the isentropic Carrollian fluid equations in one spatial dimension for a particular constitutive law ($\gamma = 3$). Our method is to use a vanishing viscosity approximation for which we establish a compensated compactness framework. Using this framework we also prove the compactness of entropy solutions in $L^\infty$, and establish a kinetic formulation of the problem. This global existence result in $L^\infty$ extends the $C^1$ theory presented in our companion paper ``One-Dimensional Carrollian Fluids II: $C^1$ Blow-up Criteria''. (10.1112/jlms.70186)
  DOI : 10.1112/jlms.70186
• Neural Projected Quantum Dynamics: a systematic study
  
  • Gravina Luca
  • Savona Vincenzo
  • Vicentini Filippo
  Quantum, Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften, 2025, 9, pp.1803. We address the challenge of simulating unitary quantum dynamics in large systems using Neural Quantum States, focusing on overcoming the computational instabilities and high cost of existing methods. This work offers a comprehensive formalization of the projected time-dependent Variational Monte Carlo (p-tVMC) method by thoroughly analyzing its two essential components: stochastic infidelity minimization and discretization of the unitary evolution. We investigate neural infidelity minimization using natural gradient descent strategies, identifying the most stable stochastic estimators and introducing adaptive regularization strategies that eliminate the need for manual adjustment of the hyperparameter along the dynamics. We formalize the specific requirements that p-tVMC imposes on discretization schemes for them to be efficient, and introduce four high-order integration schemes combining Taylor expansions, Padé approximants, and Trotter splitting to enhance accuracy and scalability. We benchmark our adaptive methods against a 2D Ising quench, matching state of the art techniques without manual tuning of hyperparameters. This work establishes p-tVMC as a highly promising framework for addressing complex quantum dynamics, offering a compelling alternative for researchers looking to push the boundaries of quantum simulations. (10.22331/q-2025-07-22-1803)
  DOI : 10.22331/q-2025-07-22-1803
• Entropy and multiplicity of hadrons in the high energy limit within dipole cascade models
  
  • Kutak Krzysztof
  • Lökös Sándor
  Physical Review D, American Physical Society, 2025, 112 (9), pp.096017. We investigate and compare QCD dipole cascade models, the 1D Mueller dipole model, its high energy limit and its generalization that follows from studies of 1D systems with conformal symmetry. To address the ambiguity stemming from different definitions of the rapidity ranges in experimental measurements, we propose the entropy as the function of the logarithm of the average multiplicity, $S(\ln\langle n \rangle)$, as a universal observable. From the solutions of the models, we calculate both the entropy and the average charged particle multiplicity and compare to data measured in proton-proton collisions. We obtained these quantities directly from the measured multiplicity distributions and determine the model parameters via fits. We find that the generalized dipole model provides a significantly better description of the data than the 1D Mueller model. (10.1103/23wn-66np)
  DOI : 10.1103/23wn-66np
• Photon Antibunching in Single-Molecule Vibrational Sum-Frequency Generation
  
  • Kalarde Fatemeh Moradi
  • Munoz Carlos Sanchez
  • Feist Johannes
  • Galland Christophe
  Nanophoton., 2025, 14 (1), pp.59-73. Sum-frequency generation (SFG) allows for coherent upconversion of an electromagnetic signal and has applications in mid-infrared vibrational spectroscopy of molecules. Recent experimental and theoretical studies have shown that plasmonic nanocavities, with their deep sub-wavelength mode volumes, may allow to obtain vibrational SFG signals from a single molecule. In this article, we compute the degree of second order coherence ($g^{(2)}(0)$) of the upconverted mid-infrared field under realistic parameters and accounting for the anharmonic potential that characterizes vibrational modes of individual molecules. On the one hand, we delineate the regime in which the device should operate in order to preserve the second-order coherence of the mid-infrared source, as required in quantum applications. On the other hand, we show that an anharmonic molecular potential can lead to antibunching of the upconverted photons under coherent, Poisson-distributed mid-infrared and visible drives. Our results therefore open a path toward a new kind of bright and tunable source of indistinguishable single photons by leveraging ``vibrational blockade'' in a resonantly and parametrically driven molecule, without the need for strong light-matter coupling. (10.1515/nanoph-2024-0469)
  DOI : 10.1515/nanoph-2024-0469
• Fractons on curved spacetime in $2+1$ dimensions
  
  • Hartong Jelle
  • Palumbo Giandomenico
  • Pekar Simon
  • Pérez Alfredo
  • Prohazka Stefan
  SciPost Physics, SciPost Foundation, 2025, 18 (1), pp.022. We study dipole Chern-Simons theory with and without a cosmological constant in $2+1$ dimensions. We write the theory in a second order formulation and show that this leads to a fracton gauge theory coupled to Aristotelian geometry which can also be coupled to matter. This coupling exhibits the remarkable property of generalizing dipole gauge invariance to curved spacetimes, without placing any limitations on the possible geometries. We also use the second order formulation to construct a higher dimensional generalization of the action. Finally, for the $(2+1)$-dimensional Chern-Simons theory we find solutions and interpret these as electric monopoles, analyze their charges and argue that the asymptotic symmetries are infinite-dimensional. (10.21468/SciPostPhys.18.1.022)
  DOI : 10.21468/SciPostPhys.18.1.022
• The exact Wheeler-DeWitt equation for the scale-factor minisuperspace model
  
  • Kaimakkamis Eftychios
  • Partouche Hervé
  • Sil Karunava
  • Toumbas Nicolaos
  Classical and Quantum Gravity, IOP Publishing, 2025, 42 (11), pp.115003. We consider the classical minisuperspace model describing a closed, homogeneous and isotropic Universe, with a positive cosmological constant. Upon canonical quantization, the infinite number of possible operator orderings in the quantum Hamiltonian leads to distinct Wheeler-DeWitt equations for the wavefunction $\psi$ of the Universe. Similarly, ambiguity arises in the path-integral formulation of $\psi$, due to the infinite choices of path-integral measures for the single degree of freedom of the model. For each choice of path-integral measure, we determine the correct operator ordering of the quantum Hamiltonian and derive the exact form of the Wheeler-DeWitt equation, including all corrections in $\hbar$. Additionally, we impose Hermiticity of the Hamiltonian to deduce the Hilbert-space measure $\mu$, which appears in the definition of the Hermitian inner product. Remarkably, all quantum predictions can be expressed through the combination $\Psi=\sqrt{\mu}\, \psi$, which satisfies a universal Wheeler-DeWitt equation, independent of the initial path-integral prescription. This result demonstrates that all seemingly distinct quantum theories arising from different quantization schemes of the same classical model are fundamentally equivalent. (10.1088/1361-6382/add705)
  DOI : 10.1088/1361-6382/add705
• Lighting up the Photon Wigner Distribution via Dilepton Productions
  
  • Shi Yu
  • Chen Lin
  • Wei Shu-Yi
  • Xiao Bo-Wen
  Physics Letters B, Elsevier, 2025, 862, pp.139317. We present a systematic investigation of lepton pair production through photon-photon fusion processes in heavy-ion collisions. It is demonstrated that the dilepton production at a given impact parameter ($b_\perp$) with a fixed transverse momentum imbalance ($q_\perp$) can be factorized into a unified formula in terms of the Wigner photon distribution of heavy nuclei. We show that this framework provides a comprehensive description of all the relevant data from RHIC to the LHC, with a strong evidence that the quasi-real photon can be radiated not only from the nucleus as a whole, standing for the coherent contribution, but also from the sub-structures inside the nucleus, representing the incoherent contribution. Further predictions are made for the anisotropies in the correlations between $q_\perp$, $b_\perp$, and the dilepton transverse momentum ($P_\perp$). This will help us to constrain the photon Wigner distribution which plays a crucial role to study the gluonic matter of nucleus at small-$x$ through the diffractive photoproduction processes in heavy ion collision. (10.1016/j.physletb.2025.139317)
  DOI : 10.1016/j.physletb.2025.139317
• Heavy-quark corner of the Columbia plot from the center-symmetric Curci-Ferrari model
  
  • Surkau V. Tomas Mari
  • Reinosa Urko
  Physical Review D, American Physical Society, 2025, 112 (1), pp.014002. We investigate the heavy-quark corner of the Columbia plot using the gluon potential derived from the Curci-Ferrari extension of the Faddeev-Popov gauge fixing in the center-symmetric Landau gauge, as a proxy for the Polyakov loop potential. In line with the observation that Landau gauge couplings are not that large in the case of heavy-quark QCD, we consider a one-loop approximation and test its consistency by using various renormalization schemes while investigating the dependence of our results on the renormalization scale. We find that the main qualitative features of the phase structure in the heavy-quark regime are reproduced. Our results agree quantitatively with those of simulations to $10\%$ accuracy, which is the expected precision of the one-loop calculations in applications of the Curci-Ferrari model to Yang-Mills or heavy-quark QCD theories. (10.1103/7dx2-vmj6)
  DOI : 10.1103/7dx2-vmj6
• Quantum Gravity, Hydrodynamics and Emergent Cosmology: A Collection of Perspectives
  
  • Ben Achour Jibril
  • Benedetti Dario
  • Bojowald Martin
  • Brandenberger Robert
  • Butera Salvatore
  • Ferrero Renata
  • Giacomini Flaminia
  • Giesel Kristina
  • Goeller Christophe
  • Haas Tobias
  • Höhn Philipp A
  • Kirklin Joshua
  • Marchetti Luca
  • Oriti Daniele
  • Percacci Roberto
  • Pereira Antonio D
  • Pithis Andreas G.A
  • Sakellariadou Mairi
  • Steinhaus Sebastian
  • Thürigen Johannes
  General Relativity and Gravitation, Springer Verlag, 2025, 57 (1), pp.2. This collection of perspective pieces captures recent advancements and reflections from a dynamic research community dedicated to bridging quantum gravity, hydrodynamics, and emergent cosmology. It explores four key research areas: (a) the interplay between hydrodynamics and cosmology, including analog gravity systems; (b) phase transitions, continuum limits and emergent geometry in quantum gravity; (c) relational perspectives in gravity and quantum gravity; and (d) the emergence of cosmological models rooted in quantum gravity frameworks. Each contribution presents the distinct perspectives of its respective authors. Additionally, the introduction by the editors proposes an integrative view, suggesting how these thematic units could serve as foundational pillars for a novel theoretical cosmology framework termed "hydrodynamics on superspace". (10.1007/s10714-024-03335-4)
  DOI : 10.1007/s10714-024-03335-4
• Complete definition of $N \rightarrow \Delta$ transition generalized parton distributions
  
  • Kim June-Young
  • Semenov-Tian-Shansky Kirill M
  • Won Ho-Yeon
  • Son Sangyeong
  • Weiss Christian
  Physical Review D, American Physical Society, 2025, 111 (11), pp.114010. We revisit the definition of the leading-twist chiral-even generalized parton distributions (GPDs) for $N \to \Delta$ baryon transitions. We identify and address deficiencies in previous definitions of the transition GPDs inspired by the transition form factors of the vector and axial-vector currents. Through systematic analysis of all possible covariant structures, respecting discrete symmetries and the baryon spinor equations of motion, we derive complete sets of independent structures for the transition matrix elements of the vector and axial-vector partonic operators. They contain additional structures proportional to the light-cone vector, corresponding to transition GPDs of vanishing first moment, which were not included in previous parametrizations. Their presence is confirmed independently by the light-front multipole expansion and the cross-channel SO(3) partial-wave analysis of the transition matrix elements. Our analysis provides a complete definition of the $N \to \Delta$ transition GPDs for use in theoretical and phenomenological studies. (10.1103/m4vj-bkqy)
  DOI : 10.1103/m4vj-bkqy
• Double DVCS amplitudes including kinematic twist-3 and 4 corrections
  
  • Martinez-Fernandez V.
  • Pire B.
  • Sznajder P.
  • Wagner J.
  Proceedings of Science, 2025, PoS(DIS2024) (PoS(DIS2024)), pp.205. Generalized parton distributions (GPDs) are off-forward matrix elements of quark and gluon operators that work as a window to the total angular momentum of partons and their transverse imaging (nucleon tomography). To access GPDs one needs to look into exclusive processes which are usually studied in a kinematic regime known as the Bj\"orken limit. In this limit, the photon virtualities are much larger than the hadron mass $M$, and the kick to the hadron measured by the Mandelstam's variable $t$. It turns out that this is not enough for the purposes of a precise GPD extraction and, in particular, of nucleon tomography for which measurements in a sizable range of $t$ are required. Deviation with respect to the Bj\"orken limit induces kinematic higher-twist corrections which enter the amplitudes with powers of $|t|/\mathbb{Q}^2$ and $M^2/\mathbb{Q}^2$, where $\mathbb{Q}^2$ denotes the scale of the process (basically, the sum of photon virtualities in the case of DDVCS). There are also corrections by the name of "genuine" higher twists which are a separate topic and are not the subject of this research study. In this manuscript, we present novel calculations of DDVCS amplitudes off a (pseudo-)scalar target including up to kinematic twist-4 corrections. These results are important for measuring DDVCS, DVCS and TCS through the Sullivan process and off helium-4 target at the future Electron-Ion Collider (EIC) and JLab experiments. Preliminary numerical estimates for the pion target are provided. (10.22323/1.469.0205)
  DOI : 10.22323/1.469.0205
• A note on non-Lorentzian duality symmetries
  
  • O'Connor Josh A
  • Pekar Simon
  Journal of High Energy Physics, Springer, 2025, 03, pp.084. We work out non-Lorentzian dual actions for electromagnetism and linearised gravity, both in the Carrollian and Galilean cases. This is done in the same way as for Lorentzian theories, by first constructing a parent action that reduces to a pair of dual actions. In the case of Maxwell theory, each pair of dual actions consists of the known `electric' and `magnetic' limits of the original theories, showing that these limits are related by an off-shell electromagnetic duality. We have obtained dualities between on one hand the non-Lorentzian contractions of linearised gravity in second-order form, and on the other hand the theories one obtains by gauging the corresponding kinematic algebras. In the Carrollian contraction, these dual actions reproduce the known `electric' and `magnetic' Carrollian theories of gravity, and we find a similar result in the Galilean case. (10.1007/JHEP03(2025)084)
  DOI : 10.1007/JHEP03(2025)084
• Near-extremal quantum cross-section for charged fields and superradiance
  
  • Betzios Panos
  • Papadoulaki Olga
  • Zhou Yanjun
  Journal of High Energy Physics, Springer, 2025, 11, pp.114. We study the scattering and absorption properties of charged scalar fields on a near-extremal Reissner-Nordström black hole background. We show that in this low-temperature regime the near-horizon throat experiences large quantum fluctuations, whose leading contribution is described by the one dimensional Schwarzian effective action, while the soft $U(1)$ gauge modes can only contribute to subleading order. We investigate the role of the leading quantum effects both inside and outside the superradiant regime. These effects result in an enhanced reflection coefficient within the superradiant regime, while causing a suppression in the non-superradiant regime. On the other hand, the absorption cross-section increases in both regimes. Additional physical features appear as kinks in the reflection coefficient and absorption cross-section plots, corresponding to the shutdown of absorption in the superradiant regime and of stimulated emission in the non-superradiant regime. (10.1007/JHEP11(2025)114)
  DOI : 10.1007/JHEP11(2025)114
• Strong-field ionization in particle-in-cell simulations
  
  • Mironov A.A
  • Gelfer E.G
  • Tupitsyn I.I
  • Beck A
  • Jirka M
  • Klimo O
  • Meuren S
  • Oberreit G
  • Smorodnikova T
  • Taïeb R
  • Weber S
  • Riconda C
  • Grech M
  • Popruzhenko S.V
  Physical Review E, American Physical Society (APS), 2025, 112 (5), pp.055202. The inclusion of the process of multiple ionization of atoms in high-intensity electromagnetic fields into particle-in-cell (PIC) codes applied to the simulation of laser-plasma interactions is a challenging task. In this paper, we first revisit ionization rates as given by the Smirnov-Chibisov and Perelomov-Popov-Terent'yev formulas within the paradigm of sequential tunnel ionization. We analyze the limit of validity and possible inconsistencies of this approach. We show that a strongly limiting factor to a precise description of ionization is the competing contribution of different sequential ionization processes. To solve this an algorithm is proposed that allows one to find the dominant nonsequential path of tunnel ionization and significantly improves the precision in simulations. This procedure is implemented in the PIC code SMILEI, and includes the dependence of the ionization rates on the magnetic quantum number of the level. The sensitivity to variations in the ionization model is studied via full simulations of the ionization of an argon target by an incident high-intensity laser pulse. Finally, we analyze generalizations of the Perelomov-Popov-Terent'yev rate developed to describe the barrier suppression ionization in high fields and discuss the necessity and possibility of including these extensions in PIC simulations. (10.1103/zlzb-kqtw)
  DOI : 10.1103/zlzb-kqtw