Publications

2024

• Many-body physics in the era of quantum simulation II
  
  • Sanchez-Palencia Laurent
  , 2024.
• Many-body physics in the era of quantum simulation I
  
  • Sanchez-Palencia Laurent
  , 2024.
• Stochastic foraging paths primarily drives within-species variations of prey consumption rates
  
  • Bansaye Vincent
  • Berthelot Geoffroy
  • El Bachari Amina
  • Chazottes Jean-René
  • Billiard Sylvain
  , 2024. The speed at which individuals interact, in particular prey and predators, affects ecological processes at all scales, including how fast matter and energy flow through ecosystems, and how stable communities are. Environmental heterogeneity and individual variabilities are generally believed to be the main factors underlying the variation of consumption rates of prey by predators. We challenge this view by comparing predicted variability from a stochastic model to experimental data. We first analyze a stochastic model of a simple random walk with elementary ecological processes involved in prey consumption, including prey depletion, predator movements and prey handling. We provide sharp approximations of the distribution of the consumption rate and a quantitative prediction of the coefficient of variation when stochastic foraging is the only source of variability. Predictions are then compared to the coefficients of variation estimated from data from dozens of various species and experimental contexts. We show that the predictions only accounting for intrinsic stochasticity in foraging are compatible with the range of observed values, in particular in 1 or 2 dimensional space. After evaluating the robustness of our model’s predictions through stochastic computer simulations, we conclude that the main driver of the variation of the consumption rate is the foraging process itself rather than environmental or between-individual variabilities. Our approach lays the foundations for unifying foraging theory and population ecology, and as such has many empirical and theoretical implications for both fields.
• Can Orbital-Selective N\'eel Transitions Survive Strong Nonlocal Electronic Correlations?
  
  • Stepanov Evgeny
  • Biermann Silke
  Physical Review Letters, American Physical Society, 2024, 132 (22), pp.226501. Spin- or orbital-selective behaviours in correlated electron materials offer rich promise for spintronics or orbitronics phenomena and applications deriving from them. Strong local electronic Coulomb correlations might lead to an orbital-selective Mott state, characterised by the coexistence of localized electrons in some orbitals with itinerant electrons in others. Nonlocal electronic fluctuations are much more entangled in orbital space than the local ones. For this reason, finding orbital-selective phenomena related to nonlocal correlations, such as orbital-selective magnetic transitions, is a challenge. In this work we investigate possibilities to realize an orbital-selective N\'eel transition (OSNT). We illustrate that stabilising this state requires a decoupling of magnetic fluctuations in different orbitals, which can only be realized in the absence of Hund's exchange coupling. On the basis of two-orbital calculations for a Hubbard model with different bandwidths we show that the proposed OSNT can be found all the way from the weak to the strong coupling regime. In the weak coupling regime the transition is governed by a Slater mechanism and thus occurs first for the narrow orbital. At strong coupling a Heisenberg mechanism of the OSNT sets in, and the transition occurs first for the wide orbital. Remarkably, at intermediate values of the interaction we find a non-trivial regime of the OSNT, where the Slater mechanism leads to a N\'eel transition occurring first for the wide orbital. Our work suggests strategies for searching for orbital-selective N\'eel ordering in real materials, in view of possible spin-orbitronics applications. (10.1103/PhysRevLett.132.226501)
  DOI : 10.1103/PhysRevLett.132.226501
• Charge Density Wave Ordering in NdNiO$_2$: Effects of Multiorbital Nonlocal Correlations
  
  • Stepanov Evgeny
  • Vandelli Matteo
  • Lichtenstein Alexander
  • Lechermann Frank
  npj Computational Materials, Springer Nature, 2024, 10 (1), pp.108. In this work, we investigate collective electronic fluctuations and, in particular, the possibility of the charge density wave ordering in an infinite-layer NdNiO$_2$. We perform advanced many-body calculations for the ab-initio three-orbital model by taking into account local correlation effects, non-local charge and magnetic fluctuations, and the electron-phonon coupling. We find that in the considered material, electronic correlations are strongly orbital- and momentum-dependent. Notably, the charge density wave and magnetic instabilities originate from distinct orbitals. In particular, we show that the correlation effects lead to the momentum-dependent hybridization between different orbitals, resulting in the splitting and shifting of the flat part of the Ni-$d_{z^2}$ band. This strong renormalization of the electronic spectral function drives the charge density wave instability that is related to the intraband Ni-$d_{z^2}$ correlations. Instead, the magnetic instability stems from the Ni-$d_{x^2-y^2}$ orbital, which remains half-filled through the redistribution of the electronic density between different bands even upon hole doping. Consequently, the strength of the magnetic fluctuations remains nearly unchanged for the considered doping levels. We argue that this renormalization is not inherent to the stoichiometric case but can be induced by hole doping. (10.1038/s41524-024-01298-3)
  DOI : 10.1038/s41524-024-01298-3
• Holographic Carrollian Conformal Scalars
  
  • Bekaert Xavier
  • Campoleoni Andrea
  • Pekar Simon
  Journal of High Energy Physics, Springer, 2024, 05, pp.242. We provide holographic realisations in Minkowski spacetime of a free conformal Carrollian scalar field living at null infinity. To this end, we first show that the electric and magnetic limits of a relativistic conformal scalar are equivalent and we study the representation of the Carroll, Poincaré and BMS algebras that is realised on the resulting solution space. We then realise it as a quotient of the solution space of a free massless scalar in Minkowski spacetime with unusual falloff, in full analogy with the interpretation of Dirac's singleton as a shortened scalar in Anti de Sitter spacetime. (10.1007/JHEP05(2024)242)
  DOI : 10.1007/JHEP05(2024)242
• Testing the scalar weak gravity conjecture in no-scale supergravity
  
  • Dudas Emilian
  • Gherghetta Tony
  • Olive Keith
  • Verner Sarunas
  Journal of High Energy Physics, Springer, 2024, 2024 (5), pp.249. A bstract We explore possible extensions of the Weak Gravity Conjecture (WGC) to scalar field theories. To avoid charged black hole remnants, the WGC requires the existence of a particle with a mass m ≤ gqM P , with charge q and U(1) gauge coupling g , allowing the decay to shed the black hole charge. Although there is no obvious problem that arises in the absence of a U(1) charge, it has been postulated that gravity must remain the weakest force even when extended to scalar interactions. Quantifying this conjecture may be done by comparing scalar and gravitational amplitudes, or as we advocate here by comparing scattering cross sections. In theories with non-trivial field space geometries, by working out examples with perturbation theory around arbitrary field values and performing tadpole resummations, we argue that the conjecture must be applied only at extrema of the scalar potential (when expressed in locally canonical coordinates). We consider several toy models in the context of no-scale supergravity and also consider examples of inflationary models. (10.1007/JHEP05(2024)249)
  DOI : 10.1007/JHEP05(2024)249
• Black hole — wormhole transitions in two dimensional string theory
  
  • Betzios Panos
  • Gaddam Nava
  • Papadoulaki Olga
  Journal of High Energy Physics, Springer, 2024, 2024 (5), pp.132. We study charged black hole and wormhole solutions of Type 0A/IIA string theory in two dimensions, by analysing their low energy equations of motion at leading order in α ′ . There is a competition between Euclidean wormholes and near extremal black holes in the thermodynamic ensemble. In a certain regime of phase space, the former can disassociate into the latter. Since such solutions are of string scale near the wormhole throat that takes an AdS 2 form, there is a need for an exact worldsheet description. We discuss relevant WZW coset models which we argue will shed light on this problem. Finally, we present appropriate versions of the Type 0A/IIA matrix quantum mechanics models that are expected to describe these geometries. (10.1007/JHEP05(2024)132)
  DOI : 10.1007/JHEP05(2024)132
• Signatures of Hund metal and finite-frequency nesting in Sr2RuO4 revealed by electronic Raman scattering
  
  • Blesio Germán
  • Beck Sophie
  • Gingras Olivier
  • Georges Antoine
  • Mravlje Jernej
  Physical Review Research, American Physical Society, 2024, 6 (2), pp.023124. We investigate the electronic Raman scattering of Sr2RuO4 using a material-realistic dynamical mean-field theory approach. We identify the low-energy Fermi liquid behavior and point out that the enhanced Raman response at higher energies is a fingerprint of Hund metals. These signatures originate in the two-stage coherence of Hund metals and associated quasiparticle "unrenormalization." In agreement with recent experimental observations, we find the B-1g and B-2g responses differ, but our calculations suggest a novel interpretation of this dichotomy. The B-1g response is dominated by the xy orbital and the B-2g response receives contributions from all orbitals and is strongly affected by previously unnoticed finite-frequency interband nesting. We calculate the vertex-corrections to Raman response and show that their effect is nonvanishing but small. (10.1103/PhysRevResearch.6.023124)
  DOI : 10.1103/PhysRevResearch.6.023124
• Quantum simulation of quasicrystals with ultracold atoms
  
  • Sanchez-Palencia Laurent
  , 2024.
• The small-$N$ series in the zero-dimensional $O(N)$ model: constructive expansions and transseries
  
  • Benedetti Dario
  • Gurau Razvan
  • Keppler Hannes
  • Lettera Davide
  Annales Henri Poincaré, Springer Verlag, 2024. We consider the 0-dimensional quartic $O(N)$ vector model and present a complete study of the partition function $Z(g,N)$ and its logarithm, the free energy $W(g,N)$, seen as functions of the coupling $g$ on a Riemann surface. Using constructive field theory techniques we prove that both $Z(g,N)$ and $W(g,N)$ are Borel summable functions along all the rays in the cut complex plane $\mathbb{C}_{\pi} =\mathbb{C}\setminus \mathbb{R}_-$. We recover the transseries expansion of $Z(g,N)$ using the intermediate field representation. We furthermore study the small-$N$ expansions of $Z(g,N)$ and $ W(g,N)$. For any $g=|g| e^{\imath \varphi}$ on the sector of the Riemann surface with $|\varphi|<3\pi/2$, the small-$N$ expansion of $Z(g,N)$ has infinite radius of convergence in $N$ while the expansion of $W(g,N)$ has a finite radius of convergence in $N$ for $g$ in a subdomain of the same sector. The Taylor coefficients of these expansions, $Z_n(g)$ and $W_n(g)$, exhibit analytic properties similar to $Z(g,N)$ and $W(g,N)$ and have transseries expansions. The transseries expansion of $Z_n(g)$ is readily accessible: much like $Z(g,N)$, for any $n$, $Z_n(g)$ has a zero- and a one-instanton contribution. The transseries of $W_n(g)$ is obtained using M\"oebius inversion and summing these transseries yields the transseries expansion of $W(g,N)$. The transseries of $W_n(g)$ and $W(g,N)$ are markedly different: while $W(g,N)$ displays contributions from arbitrarily many multi-instantons, $W_n(g)$ exhibits contributions of only up to $n$-instanton sectors. (10.1007/s00023-024-01437-y)
  DOI : 10.1007/s00023-024-01437-y
• Near-critical dark opalescence in out-of-equilibrium SF6
  
  • Martelli Valentina
  • Anquetil Amaury
  • Atik Lin Al
  • Jiménez J. Larrea
  • Subedi Alaska
  • Lobo Ricardo P. S. M.
  • Behnia Kamran
  Communications Physics, Nature Research, 2024, 7 (1), pp.133. Abstract The first-order phase transition between the liquid and gaseous phases ends at a critical point. Critical opalescence occurs at this singularity. Discovered in 1822, it is known to be driven by diverging fluctuations in the density. During the past two decades, boundaries between the gas-like and liquid-like regimes have been theoretically proposed and experimentally explored. Here, we show that fast cooling of near-critical sulfur hexafluoride (SF 6 ), in presence of Earth’s gravity, favors dark opalescence, where visible photons are not merely scattered, but also absorbed. When the isochore fluid is quenched across the critical point, its optical transmittance drops by more than three orders of magnitude in the whole visible range, a feature which does not occur during slow cooling. We show that transmittance shows a dip at 2eV near the critical point, and the system can host excitons with binding energies ranging from 0.5 to 4 eV. The spinodal decomposition of the liquid-gas mixture, by inducing a periodical modulation of the fluid density, can provide a scenario to explain the emergence of this platform for coupling between light and matter. The possible formation of excitons and polaritons points to the irruption of quantum effects in a quintessentially classical context. (10.1038/s42005-024-01622-9)
  DOI : 10.1038/s42005-024-01622-9
• Rigid vacua with Brane Supersymmetry Breaking
  
  • Angelantonj Carlo
  • Condeescu Cezar
  • Dudas Emilian
  • Leone Giorgio
  Journal of High Energy Physics, Springer, 2024, 2024 (4), pp.103. We construct new string vacua featuring Brane Supersymmetry Breaking, based on T 4 /ℤ N orientifolds with O5 + planes and $\overline{\text{D}5}$ branes. Differently from the original construction, in these vacua the cancellation of twisted R-R charges of D-branes and orientifold planes is achieved in a non-trivial way, and results in rigid configurations with few open-string moduli, which highly restrict the possible deformations of the model. The breaking of supersymmetry and, consequently, the non-vanishing untwisted and twisted NS-NS tadpoles, generates a rich potential both for the dilaton and the blown-up moduli. We also uncover the stringy origin of the J form entering the gauge kinetic functions in the low-energy effective action, and display its relation to the NS-NS tadpoles for the scalars in the tensor multiplets. As a result, the J form can be consistently identified also when supersymmetry is broken, thus solving an embarrassing puzzle related to its very existence. We also discuss the unitarity constraints for one-dimensional defects in these vacua, where the Kač-Moody algebra for D9 and $\overline{\text{D}5}$ can be realised both in the left-moving and right-moving sectors. (10.1007/JHEP04(2024)103)
  DOI : 10.1007/JHEP04(2024)103
• Kinematical higher-twist corrections in gamma* to M_1 bar M_2 gamma: II. Charged meson production
  
  • Pire Bernard
  • Song Qin-Tao
  Physical Review D, American Physical Society, 2024, 109 (07), pp.074016. Generalized distribution amplitudes (GDAs) of mesons can be probed by the reactions $e^- e^+ \to M_1 M_2 \gamma$, which are accessible at electron-positron colliders such as BESIII and Belle II. After discussing the neutral meson production case in the first paper of this series, we discuss here the complementary case of the charged meson ($M^+ M^-$) production, where one can extract the complete information on GDAs from the interference of the amplitudes of the two competing processes where the photon is emitted either in the initial or in the final state. Considering the importance of the charged meson production, we present a complete expression for the interference term of the cross section which is experimentally accessible thanks to its charge conjugation specific property. We adopt two types of models for leading twist $\pi \pi$ GDAs to estimate the size of the interference term in the process $e^- e^+ \to \pi^+ \pi^- \gamma$ numerically, namely a model extracted from previous experimental results on $\gamma^* \gamma \to \pi^0 \pi^0$ at Belle and the asymptotic form predicted by QCD evolution equations. We include in the calculation the kinematical higher-twist corrections up to twist 4 for the helicity amplitudes. Both models of GDAs indicate that the kinematical corrections are not negligible for the interference term of the cross section measured at BESIII, thus it is necessary to include them if we try to extract the GDAs precisely. On the other side, the kinematical corrections are very tiny for the measurements at Belle II, and the leading twist-2 formula of the interference term will be good enough to describe the charge conjugation odd part of the differential cross section. (10.1103/PhysRevD.109.074016)
  DOI : 10.1103/PhysRevD.109.074016
• Can we measure Double DVCS at JLab and the EIC?
  
  • Deja K.
  • Martinez-Fernandez V.
  • Pire B.
  • Sznajder P.
  • Wagner J.
  PoS - Proceedings of Science, SISSA, 2024, PoS(SPIN2023), pp.148. Double deeply virtual Compton scattering (DDVCS) is a very precise tool for the nucleon tomography. Its measurement requires high luminosity electron beams and precise dedicated detectors, since its amplitude is quite small in the interesting kinematical domain where collinear QCD factorization allows the extraction of quark and gluon generalized parton distributions (GPDs). We analyze the prospects for its study in the JLab energy domain as well as in higher energy electron-ion colliders. Our results are very encouraging for various observables both with an unpolarized and polarized lepton beam. Using various realistic models for GPDs, we demonstrate that DDVCS measurements are indeed very sensitive to their behaviour. Implementing our lowest order cross-section formulae in the EpIC Monte Carlo generator, we estimate the expected number of interesting events.
• Branching diffusion processes and spectral properties of Feynman-Kac semigroup
  
  • Collet Pierre
  • Méléard Sylvie
  • San MARTIN Jaime
  , 2024. In this article we study the long time behavior of linear functionals of branching diffusion processes as well as the time reversal of the spinal process by means of spectral properties of the Feynman-Kac semigroup. We generalize for this non Markovian semigroup the theory of quasi-stationary distribution (q.s.d.) and Q-process. The most amazing result is the identification of the law of the reversal time spinal process issued from q.s.d. with the Q-process of the Feynman-Kac semigroup.
• Thermoelectric Transport Properties of Electron-Doped Pyrite FeS2
  
  • Mukherjee Anustup
  • Subedi Alaska
  Journal of Physical Chemistry C, American Chemical Society, 2024, 128 (16), pp.6573-6580. Pyrite FeS2 has been investigated for a wide range of applications, including thermoelectrics, due to previous observations of large thermopower at room temperature. However, the values of thermopower reported in the literature are extremely sensitive to the nature of the sample─whether they are natural or lab-grown, bulk crystals or thin films─and an ambiguity in the magnitude and sign of the thermopower of pure FeS2 exists. Variation in the magnitude of room-temperature thermopower has also been observed in Co-doped samples. Therefore, it is of interest to clarify the intrinsic thermopower of this system that could be measured in more pure samples. In this paper, we investigate the thermoelectric properties of Co-doped FeS2 using first-principles calculations. We apply three different doping schemes to understand the effect of electron doping in FeS2, namely, explicit Co substitution, jellium doping, and electron addition within a rigid band approximation (RBA) picture. The calculated thermopower is less than −50 μV/K for all values of Co doping that we studied, suggesting that this system may not be useful in thermoelectric applications. Interestingly, we find that RBA substantially overestimates the magnitude of calculated thermopower compared to the explicit Co substitution and jellium doping schemes. The overestimation occurs because the changes in the electronic structure due to doping-induced structural modification and charge screening are not taken into account by the rigid shift of the Fermi level within RBA. RBA is frequently used in first-principles investigations of the thermopower of doped semiconductors, and Co-substituted FeS2 illustrates a case where it fails. (10.1021/acs.jpcc.4c00147)
  DOI : 10.1021/acs.jpcc.4c00147
• 3D structure of hadrons and energy-momentum tensor
  
  • Lorcé Cédric
  , 2025, DIS2024, pp.003. The three-dimensional spatial structure of hadrons is encoded in their form factors. Via appropriate Fourier transform, the latter describe how charge, energy, linear and angular momentum, but also pressure are distributed inside these systems. Electromagnetic form factors of the nucleon have been measured for a long time, but it is only recently that some gravitational form factors have been extracted from experimental data, creating a great deal of enthusiasm in the hadronic community. Here we summarize some of the recent developments on the interpretation of these form factors, and provide a quick overview of what we can learn about the nucleon mass, spin and internal pressure. (10.22323/1.469.0003)
  DOI : 10.22323/1.469.0003
• Asymptotic Symmetries for Logarithmic Soft Theorems in Gauge Theory and Gravity
  
  • Choi Sangmin
  • Laddha Alok
  • Puhm Andrea
  , 2024. Gauge theories and perturbative gravity in four dimensions are governed by a tower of infinite-dimensional symmetries which arise from tree-level soft theorems. However, aside from the leading soft theorems which are all-loop exact, subleading ones receive loop corrections due to long-range infrared effects which result in new soft theorems with logarithmic dependence on the energy of the soft particle. The conjectured universality of these logarithmic soft theorems to all loop orders cries out for a symmetry interpretation. In this letter we initiate a program to compute long-range infrared corrections to the charges that generate the asymptotic symmetries in (scalar) QED and perturbative gravity. For late-time fall-offs of the electromagnetic and gravitational fields which give rise to infrared dressings for the matter fields, we derive finite charge conservation laws and show that in the quantum theory they correspond precisely to the first among the infinite tower of logarithmic soft theorems. This symmetry interpretation, by virtue of being universal and all-loop exact, is a key element for a holographic principle in spacetimes with flat asymptotics.
• Gluon tomography through diffractive processes in a saturation framework
  
  • Boussarie Renaud
  • Fucilla Michael
  • Grabovsky Andrey V
  • Li Emilie
  • Szymanowski Lech
  • Wallon Samuel
  , 2025, DIS2024, pp.090. We discuss a series of results aimed at bringing saturation physics and gluon tomography into an era of precision. In particular, the NLO treatment of diffractive: 1) exclusive dijet, 2) exclusive longitudinally polarized light vector meson and 3) semi-inclusive single or double hadron photo- or electroproduction with large $p_T$, on a nucleon or a nuclei. Finally, we discuss the more complicated 4) exclusive transversely polarized light vector meson production, which starts at the next-to-leading power and therefore requires a beyond leading twist treatment. This new class of processes provides an access to precision physics of gluon saturation dynamics, with very promising future phenomenological studies at the EIC, or, at the LHC in $p A$ and $A A$ scattering, using Ultra Peripheral Collisions (UPC). (10.22323/1.469.0090)
  DOI : 10.22323/1.469.0090
• The Hund-metal path to strong electronic correlations
  
  • Georges Antoine
  • Kotliar Gabriel
  Physics today, American Institute of Physics, 2024, 77 (4), pp.46-53. A new type of metal has taken the scientific community by surprise. Classic concepts from atomic physics—the electrons’ orbitals and spin alignment—are key to understanding it. (10.1063/pt.wqrz.qpjx)
  DOI : 10.1063/pt.wqrz.qpjx
• Rigid Vacua with Brane Supersymmetry Breaking
  
  • Angelantonj Carlo
  • Condeescu Cezar
  • Dudas Emilian
  • Leone Giorgio
  , 2024. We construct new string vacua featuring Brane Supersymmetry Breaking, based on $T^4/\mathbb{Z}_N$ orientifolds with $\text{O}5_+$ planes and $\overline{\text{D}5}$ branes. Differently from the original construction, in these vacua the cancellation of twisted R-R charges of D-branes and orientifold planes is achieved in a non-trivial way, and results in rigid configurations with few open-string moduli, which highly restrict the possible deformations of the model. The breaking of supersymmetry and, consequently, the non-vanishing untwisted and twisted NS-NS tadpoles, generates a rich potential both for the dilaton and the blown-up moduli. We also uncover the stringy origin of the $J$ form entering the gauge kinetic functions in the low-energy effective action, and display its relation to the NS-NS tadpoles for the scalars in the tensor multiplets. As a result, the $J$ form can be consistently identified also when supersymmetry is broken, thus solving an embarrassing puzzle related to its very existence. We also discuss the unitarity constraints for one-dimensional defects in these vacua, where the Ka$\check{\text{c}}$-Moody algebra for D9 and $\overline{\text{D}5}$ can be realised both in the left-moving and right-moving sectors.
• Wilson loops and wormholes
  
  • Betzios Panos
  • Papadoulaki Olga
  Journal of High Energy Physics, Springer, 2024, 2024 (3), pp.66. We analyse the properties of Wilson loop observables for holographic gauge theories, when the dual bulk geometries have a single and/or multiple boundaries (Euclidean spacetime wormholes). Such observables lead to a generalisation and refinement of the characterisation in [1] based on the compressibility of cycles and the pinching limit of higher genus Riemann surfaces, since they carry information about the dynamics and phase structure of the dual gauge theory of an arbitrary dimensionality. Finally, we describe how backreacting correlated observables such as Wilson loops can lead to wormhole saddles in the dual gravitational path integral, by taking advantage of a representation theoretic entanglement structure proposed in [13, 15]. (10.1007/JHEP03(2024)066)
  DOI : 10.1007/JHEP03(2024)066
• Flat-space Partial Waves From Conformal OPE Densities
  
  • van Rees Balt C
  • Zhao Xiang
  , 2024. We consider the behavior of the OPE density $c(\Delta,\ell)$ for conformal four-point functions in the flat-space limit where all scaling dimensions become large. We find evidence that the density reduces to the partial waves $f_\ell(s)$ of the corresponding scattering amplitude. The Euclidean inversion formula then reduces to the partial wave projection and the Lorentzian inversion formula to the Froissart-Gribov formula. The flat-space limit of the OPE density can however also diverge, and we delineate the domain in the complex $s$ plane where this happens. Finally we argue that the conformal dispersion relation reduces to an ordinary single-variable dispersion relation for scattering amplitudes.
• Shock formation in flowing plasmas by temporally and spatially smoothed laser beams
  
  • Ludwig J D
  • Hüller S
  • Rose H A
  • Bruulsema C
  • Farmer W
  • Michel P
  • Milder A
  • Swadling G F
  • Rozmus W
  Physics of Plasmas, American Institute of Physics, 2024, 31, pp.032103. The cumulative impact of multiple laser speckles on the supersonic plasma flow across optically smoothed laser beams is investigated. The bending of the laser beams caused by ponderomotive laser-plasma coupling, together with flow, lead to plasma response by momentum conservation that results in a deceleration of the flow. Once the flow velocity decreases to a subsonic level, the action of the laser beams can generate a shock within the plasma. This scenario has been predicted theoretically and confirmed by hydrodynamic simulations. The conditions of shock generation are given in terms of the ponderomotive pressure, speckle size and the flow velocity. The nonlinear properties of the shocks are analyzed using Rankine-Hugoniot relations. According to linear theory, temporally smoothed beams exhibit a higher threshold for shock generation. Numerical simulations with beams that are smoothed by spectral dispersion compare well with the linear theory results, diverging from those produced by beams with only a random phase plates in the nonlinear regime. The conditions necessary for shock generation and their effects on the laser plasma coupling in the inertial confinement fusion experiments are also discussed. (10.1063/5.0189559)
  DOI : 10.1063/5.0189559