Publications

2022

• Holographic Lorentz and Carroll Frames
  
  • Campoleoni Andrea
  • Ciambelli Luca
  • Delfante Arnaud
  • Marteau Charles
  • Petropoulos P. Marios
  • Ruzziconi Romain
  , 2022. Relaxing the Bondi gauge, the solution space of three-dimensional gravity in the metric formulation has been shown to contain an additional free function that promotes the boundary metric to a Lorentz or Carroll frame, in asymptotically AdS or flat spacetimes. We pursue this analysis and show that the solution space also admits a finite symplectic structure, obtained taking advantage of the built-in ambiguities. The smoothness of the flat limit of the AdS symplectic structure selects a prescription in which the holographic anomaly appears in the boundary Lorentz symmetry, that rotates the frame. This anomaly turns out to be cohomologically equivalent to the standard holographic Weyl anomaly and survives in the flat limit, thus predicting the existence of quantum anomalies in conformal Carrollian field theories. We also revisit these results in the Chern--Simons formulation, where the prescription for the symplectic structure admitting a smooth flat limit follows from the variational principle, and we compute the charge algebra in the boundary conformal gauge.
• Ce and Dy substitutions in Nd2Fe14B : Site-specific magnetic anisotropy from first principles
  
  • Boust James
  • Aubert Alex
  • Fayyazi Bahar
  • Skokov Konstantin
  • Skourski Yurii
  • Gutfleisch Oliver
  • Pourovskii Leonid
  Physical Review Materials, American Physical Society, 2022, 6 (8), pp.084410. (10.1103/PhysRevMaterials.6.084410)
  DOI : 10.1103/PhysRevMaterials.6.084410
• Multi-band D-TRILEX approach to materials with strong electronic correlations
  
  • Vandelli Matteo
  • Kaufmann Josef
  • El-Nabulsi Mohammed
  • Harkov Viktor
  • Lichtenstein Alexander
  • Stepanov Evgeny
  SciPost Physics, SciPost Foundation, 2022, 13 (2), pp.036. We present the multi-band dual triply irreducible local expansion (D-TRILEX) approach to interacting electronic systems and discuss its numerical implementation. This method is designed for a self-consistent description of multi-orbital systems that can also have several atoms in the unit cell. The current implementation of the D-TRILEX approach is able to account for the frequency- and channel-dependent long-ranged electronic interactions. We show that our method is accurate when applied to small multi-band systems such as the Hubbard-Kanamori dimer. Calculations for the extended Hubbard, the two-orbital Hubbard-Kanamori, and the bilayer Hubbard models are also discussed. (10.21468/SciPostPhys.13.2.036)
  DOI : 10.21468/SciPostPhys.13.2.036
• Two-loop three-gluon vertex from the Curci-Ferrari model and its leading infrared behavior to all loop orders
  
  • Barrios Nahuel
  • Peláez Marcela
  • Reinosa Urko
  , 2022. We evaluate the three-gluon vertex with one vanishing external momentum within the Curci-Ferrari (CF) model at two-loop order and compare our results to Landau-gauge lattice simulations of the same vertex function for the SU(2) and SU(3) gauge groups in four dimensions. The parameters of the model being adjusted by fitting the two-point functions to lattice data, our evaluation of the three-gluon vertex arises as a pure prediction. We find that two-loop corrections systematically improve the agreement between the model and the lattice data as compared to earlier one-loop calculations, with a better agreement in the SU(3) case, as already seen in previous studies [1,2]. We also analyze the renormalization scheme dependence of our calculation. In all cases, this dependence diminishes when two-loop corrections are included, which is consistent with the perturbative CF paradigm. In addition, we study the low momentum regime of the three-gluon vertex in relation with the possibility of zero-crossing. Within the CF model, we show that the leading infrared behavior of the exact vertex is given by the same linear logarithm that arises at one-loop order, multiplied by the all orders cubic ghost dressing function at zero-momentum (we provide similar exact results for other vertex functions). We argue that this property remains true within the FP framework under the assumption that the resummed gluon propagator features a decoupling behavior. This shows that the zero-crossing is a property of the exact three-gluon vertex function. Within the CF model, we find however that the scale of the zero-crossing is considerably reduced when going from one- to two-loop order. This seems consistent with some recent lattice simulations [3]. Our analysis also allows us to support recent claims about the dominance of the tree-level tensor component [4].
• Eliminating Orbital Selectivity from the Metal-Insulator Transition by Strong Magnetic Fluctuations
  
  • Stepanov Evgeny
  Physical Review Letters, American Physical Society, 2022, 129 (9), pp.096404. (10.1103/PhysRevLett.129.096404)
  DOI : 10.1103/PhysRevLett.129.096404
• A novel formulation of the unintegrated gluon distribution for DIS
  
  • Boussarie Renaud
  • Mehtar-Tani Yacine
  Physics Letters B, Elsevier, 2022, 831, pp.137125. (10.1016/j.physletb.2022.137125)
  DOI : 10.1016/j.physletb.2022.137125
• Formation of an Electron-Phonon Bifluid in Bulk Antimony
  
  • Jaoui Alexandre
  • Gourgout Adrien
  • Subedi Alaska
  • Lorenz Thomas
  • Fauqué Benoît
  • Behnia Kamran
  • Seyfarth Gabriel
  Physical Review X, American Physical Society, 2022, 12 (3), pp.031023. The flow of charge and entropy in solids usually depends on collisions decaying quasiparticle momentum. Hydrodynamic corrections can emerge, however, if most collisions among quasiparticles conserve momentum and the mean-free-path approaches the sample dimensions. Here, through a study of electrical and thermal transport in antimony (Sb) crystals of various sizes, we document the emergence of a two-component fluid of electrons and phonons. Lattice thermal conductivity is dominated by electron scattering down to 0.1 K and displays prominent quantum oscillations. The Dingle mobility does not vary despite an order-of-magnitude change in transport mobility. The Bloch-Grüneisen behavior of electrical resistivity is suddenly aborted below 15 K and replaced by a quadratic temperature dependence. At Kelvin temperature range, the phonon scattering time and the electron-electron scattering time display a similar amplitude and temperature dependence. Taken together, the results draw a consistent picture of a bi-fluid where frequent momentumconserving collisions between electrons and phonons dominate the transport properties. (10.1103/PhysRevX.12.031023)
  DOI : 10.1103/PhysRevX.12.031023
• Backward timelike Compton scattering to decipher the photon content of the nucleon
  
  • Pire Bernard
  • Semenov-Tian-Shansky Kirill M.
  • Shaikhutdinova Alisa A.
  • Szymanowski Lech
  European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2022. The exclusive photoproduction off nucleon of a large invariant mass lepton pair in the backward region specified by the small Mandelstam variable -u is discussed in the framework of collinear QCD factorization. The amplitude is factorized in terms of photon-to-nucleon Transition Distribution Amplitudes (TDAs) which encode the photon content of the nucleon. Model estimates of these new non-perturbative objects are described and the corresponding cross sections calculated. The background due to the electromagnetic Bethe-Heitler process is shown to be negligible in the kinematical regime of interest. (10.1140/epjc/s10052-022-10587-4)
  DOI : 10.1140/epjc/s10052-022-10587-4
• Predictions for the sPHENIX physics program
  
  • Belmont Ron
  • Brewer Jasmine
  • Brodsky Quinn
  • Caucal Paul
  • Connors Megan
  • Djordjevic Magdalena
  • Ehlers Raymond
  • Escobedo Miguel A
  • Ferreiro Elena G
  • Giacalone Giuliano
  • Hatta Yoshitaka
  • Holguin Jack
  • Ke Weiyao
  • Kang Zhong-Bo
  • Kumar Amit
  • Mazeliauskas Aleksas
  • Mehtar-Tani Yacine
  • Nukazuka Genki
  • Pablos Daniel
  • Perepelitsa Dennis V
  • Rajagopal Krishna
  • Sickles Anne M
  • Strickland Michael
  • Tywoniuk Konrad
  • Vitev Ivan
  • Wang Xin-Nian
  • Yang Zhong
  • Zhao Fanyi
  , 2024, 1043, pp.122821. sPHENIX is a next-generation detector experiment at the Relativistic Heavy Ion Collider, designed for a broad set of jet and heavy-flavor probes of the Quark-Gluon Plasma created in heavy ion collisions. In anticipation of the commissioning and first data-taking of the detector in 2023, a RIKEN-BNL Research Center (RBRC) workshop was organized to collect theoretical input and identify compelling aspects of the physics program. This paper compiles theoretical predictions from the workshop participants for jet quenching, heavy flavor and quarkonia, cold QCD, and bulk physics measurements at sPHENIX. (10.1016/j.nuclphysa.2024.122821)
  DOI : 10.1016/j.nuclphysa.2024.122821
• Causality constraints on nonlinear supersymmetry
  
  • Bonnefoy Quentin
  • Casagrande Gabriele
  • Dudas Emilian
  , 2022. It is well-known that gravitino propagation in standard supergravities is free of any causality problems. However, two issues related to gravitino propagation were recently uncovered in specific supergravities with nonlinear supersymmetry. One of them concerns potential acausality/superluminality, whereas the second one arises from the vanishing of the sound speed at specific points during inflation. The former is famously related to positivity constraints on specific EFT operators, derived from dispersion relations on the energy-growing part of scattering amplitudes, and indeed we show that subluminality constraints for the gravitino are related via the equivalence theorem to positivity bounds in low-energy goldstino actions. However, the former are stronger, in the sense that they apply to functions of the scalar fields not only in the ground state, but for any field values such as those scanned by time-dependent solutions, unlike bounds derived from $2\to 2$ scattering amplitudes in the vacuum. We also argue that nontrivial causality constraints arise only in the case where nonlinear supersymmetry in the matter sector is encoded into superfield constraints which do not seem to arise from microscopic two-derivative lagrangians, in particular for the orthogonal constraint used to build minimal models of inflation in supergravity. This allows us to propose simple alternatives which maintain the minimality of the spectra and are causal in all points of the theory parameter space. We also discuss minimal supergravity models of inflation along these lines.
• Modeling magnetic multipolar phases in density functional theory
  
  • Fiore Mosca Dario
  • Pourovskii Leonid
  • Franchini Cesare
  Physical Review B, American Physical Society, 2022, 106 (3), pp.035127. (10.1103/PhysRevB.106.035127)
  DOI : 10.1103/PhysRevB.106.035127
• Snowmass 2021 White Paper: Electron Ion Collider for High Energy Physics
  
  • Abdul Khalek R.
  • d'Alesio U.
  • Arratia Miguel
  • Bacchetta A.
  • Battaglieri M.
  • Begel M.
  • Boglione M.
  • Boughezal R.
  • Boussarie Renaud
  • Bozzi G.
  • Chekanov S.V.
  • Celiberto F.G.
  • Chirilli G.
  • Cridge T.
  • Cruz-Torres R.
  • Corliss R.
  • Cotton C.
  • Davoudiasl H.
  • Deshpande A.
  • Dong Xin
  • Emmert A.
  • Fazio S.
  • Forte S.
  • Furletova Yulia
  • Gal Ciprian
  • Gwenlan Claire
  • Guzey V.
  • Harland-Lang L.A.
  • Helenius I.
  • Hentschinski M.
  • Hobbs Timothy J.
  • Höche S.
  • Hou T.-J.
  • Ji Y.
  • Jing X.
  • Kelsey M.
  • Klasen M.
  • Kang Zhong-Bo
  • Kovchegov Y.V.
  • Kumar K.S.
  • Lappi Tuomas
  • Lee K.
  • Lee Yen-Jie
  • Li H.-T.
  • Li X.
  • Lin H.-W.
  • Liu H.
  • Liu Z.L.
  • Liuti S.
  • Lorcé C.
  • Lunghi E.
  • Marcarelli R.
  • Magill S.
  • Makris Y.
  • Mantry S.
  • Melnitchouk W.
  • Mezrag C.
  • Moch S.
  • Moutarde H.
  • Mukherjee Swagato
  • Murgia F.
  • Nachman B.
  • Nadolsky P.M.
  • Nam J.D.
  • Neill D.
  • Neill E.T.
  • Nocera E.
  • Nycz M.
  • Olness F.
  • Petriello F.
  • Pitonyak D.
  • Plätzer S.
  • Prestel Stefan
  • Prokudin Alexei
  • Qiu J.
  • Radici M.
  • Radhakrishnan S.
  • Sadofyev A.
  • Rojo J.
  • Ringer F.
  • Salazar Farid
  • Sato N.
  • Schenke Björn
  • Schlichting Sören
  • Schweitzer P.
  • Sekula S.J.
  • Shao D.Y.
  • Sherrill N.
  • Sichtermann E.
  • Signori A.
  • Şimşek K.
  • Simonelli A.
  • Sznajder P.
  • Tezgin K.
  • Thorne R.S.
  • Tricoli A.
  • Venugopalan R.
  • Vladimirov A.
  • Vicini Alessandro
  • Vitev Ivan
  • Wiegand D.
  • Wong C.-P.
  • Xie K.
  • Zaccheddu M.
  • Zhao Y.
  • Zhang J.
  • Zheng X.
  • Zurita P.
  , 2022. Electron Ion Collider (EIC) is a particle accelerator facility planned for construction at Brookhaven National Laboratory on Long Island, New York by the United States Department of Energy. EIC will provide capabilities of colliding beams of polarized electrons with polarized beams of proton and light ions. EIC will be one of the largest and most sophisticated new accelerator facilities worldwide, and the only new large-scale accelerator facility planned for construction in the United States in the next few decades. The versatility, resolving power and intensity of EIC will present many new opportunities to address some of the crucial and fundamental open scientific questions in particle physics. This document provides an overview of the science case of EIC from the perspective of the high energy physics community.
• White Paper on Forward Physics, BFKL, Saturation Physics and Diffraction
  
  • Hentschinski Martin
  • Royon Christophe
  • Peredo Marco Alcazar
  • Baldenegro Cristian
  • Bellora Andrea
  • Boussarie Renaud
  • Celiberto Francesco Giovanni
  • Cerci Salim
  • Chachamis Grigorios
  • Contreras J.G.
  • Fichet Sylvain
  • Fucilla Michael
  • von Gersdorff Gero
  • González Pablo
  • van Hameren Andreas
  • Jalilian-Marian Jamal
  • Kampshoff Mats
  • Khoze Valery
  • Klasen Michael
  • Klein Spencer Robert
  • Krintiras Georgios
  • Kotko Piotr
  • Kutak Krzysztof
  • Lansberg Jean-Philippe
  • Li Emilie
  • Loizides Constanin
  • Mohammed Mohammed M.A.
  • Nefedov Maxim
  • Ozcelik Melih A.
  • Papa Alessandro
  • Pitt Michael
  • Vera Agustin Sabio
  • Salomon Jens
  • Sapeta Sebastian
  • da Silveira Gustavo Gil
  • Gonçalves Victor Paulo
  • Strikman Mark
  • Cerci Deniz Sunar
  • Szymanowski Lech
  • Takaki Daniel Tapia
  • Taševský Marek
  • Wallon Samuel
  , 2023, 54 (3), pp.2. The goal of this whitepaper is to give a comprehensive overview of the rich field of forward physics. We discuss the occurrences of BFKL resummation effects in special final states, such as Mueller-Navelet jets, jet gap jets, and heavy quarkonium production. It further addresses TMD factorization at low x and the manifestation of a semi-hard saturation scale in (generalized) TMD PDFs. More theoretical aspects of low x physics, probes of the quark gluon plasma, as well as the possibility to use photon-hadron collisions at the LHC to constrain hadronic structure at low x, and the resulting complementarity between LHC and the EIC are also presented. We also briefly discuss diffraction at colliders as well as the possibility to explore further the electroweak theory in central exclusive events using the LHC as a photon-photon collider. (10.5506/APhysPolB.54.3-A2)
  DOI : 10.5506/APhysPolB.54.3-A2
• 4D spatio-temporal electric field characterization of ultrashort light pulses undergoing filamentation
  
  • Neoričić Lana
  • Jusko Christoph
  • Mikaelsson Sara
  • Guo Chen
  • Miranda Miguel
  • Zhong Shiyang
  • Garmirian Félix
  • Major Balázs
  • Brown Jeffrey M
  • Gaarde Mette B
  • Couairon Arnaud
  • Morgner Uwe
  • Kovačev Milutin
  • Arnold Cord L
  Optics Express, Optical Society of America - OSA Publishing, 2022, 30. We present an experimental method capable of capturing the complete spatiotemporal dynamics of filamenting ultrashort laser pulses. By employing spatially resolved Fourier transform spectrometry in combination with the capability to terminate the filament at any length, we can follow the nonlinear dynamics in four dimensions, i.e. the transverse domain, time and filament length. Our method thus not only enables the full characterization of the filamentation process throughout its evolution, but also allows to identify and select laser pulses with desired parameters. (10.1364/oe.461388)
  DOI : 10.1364/oe.461388
• Electronic structure of the highly conductive perovskite oxide SrMoO 3
  
  • Cappelli E.
  • Hampel A.
  • Chikina A.
  • Guedes E. Bonini
  • Gatti G.
  • Hunter A.
  • Issing J.
  • Biskup N.
  • Varela M.
  • Dreyer C.
  • Tamai A.
  • Georges A.
  • Bruno F.
  • Radovic M.
  • Baumberger F.
  Physical Review Materials, American Physical Society, 2022, 6 (7), pp.075002. We use angle-resolved photoemission to map the Fermi surface and quasiparticle dispersion of bulklike thin films of SrMoO3 grown by pulsed laser deposition. The electronic self-energy deduced from our data reveals weak to moderate correlations in SrMoO3, consistent with our observation of well-defined electronic states over the entire occupied bandwidth. We further introduce spectral function calculations that combine dynamical mean-field theory with an unfolding procedure of density functional calculations and demonstrate good agreement of this approach with our experiments. (10.1103/PhysRevMaterials.6.075002)
  DOI : 10.1103/PhysRevMaterials.6.075002
• Filamentation of collimated 744 nm beam under amplitude modulation
  
  • Mokrousova D.V.
  • Rizaev G.E.
  • Koribut A.V.
  • Panov N.A.
  • Nikolaeva I.A.
  • Shipilo D.E.
  • Mitina E.V.
  • Pushkarev D.V.
  • Couairon A.
  • Houard A.
  • Savel'Ev A.B.
  • Kosareva O.G.
  • Seleznev L.V.
  • Ionin A.A.
  , 2022, pp.1-1. (10.1109/ICLO54117.2022.9839914)
  DOI : 10.1109/ICLO54117.2022.9839914
• Renormalization in tensor field theory and the melonic fixed point
  
  • Harribey Sabine
  , 2022. This thesis focuses on the study of the renormalization group flow in tensor field theories. Its first part considers a quartic tensor model with O(N)3 symmetry and long-range propagator. The existence of a non-perturbative fixed point in any d at large N is established. We found four lines of fixed points parametrized by the so-called tetrahedral coupling. One of them is infrared attractive, strongly interacting and gives rise to a new kind of conformal field theories, called melonic CFTs. This melonic CFT is then studied in more details. We first compute dimensions of bilinears and operator product expansion coefficients at the fixed point. The results are consistent with a unitary CFT at large N. We then compute 1/N corrections to the fixed point. At next-to-leading order, the line of fixed points collapses to one fixed point. However, the corrections are complex and unitarity is broken at next-to-leading order. Finally, the F-theorem is investigated for this model. This theorem states that the free energy of a CFT on the sphere in dimension 3 decreases along the renormalization group flow. We show that our model respects this theorem.The next part of the thesis investigates sextic tensor field theories in rank 3 and 5. In rank 3, we found two infrared stable real fixed points in short range and a line of infrared stable real fixed points in long range. Surprisingly, the only fixed point in rank 5 is the Gaussian one. For the rank 3 model, in the short-range case, we still find two infrared stable fixed points at next-to-leading order. However, in the long-range case, the corrections to the fixed points are non-perturbative and hence unreliable: we found no precursor of the large N fixed point.The last part of the thesis investigates the class of model exhibiting a melonic large N limit. Indeed, this limit was lacking for models with ordinary tensor representations of O(N) and Sp(N), such as symmetric traceless or antisymmetric ones. Recently, it was proven that models with tensors in an irreducible representation of O(N) or Sp(N) in rank 3 indeed admit a large N limit. This proof is here extended in rank 5. This generalization relies on recursive bounds derived from a detailed combinatorial analysis of Feynman graphs involved in the perturbative expansion of our model. (10.70675/a907e881zbcf1z49b8za5dczfe92aee45669)
  DOI : 10.70675/a907e881zbcf1z49b8za5dczfe92aee45669
• Holography, hydrodynamics and strongly-correlated condensed matter
  
  • Gouteraux Blaise
  , 2022.
• Ultrafast spectroscopy applied to photoinduced phase transition
  
  • Privault Gaël
  • Collet Eric
  • Lorenc Maciej
  • Humbert Bernard
  • Subedi Alaska
  , 2022.
• Perturbative higher-derivative terms in N = 6 asymmetric orbifolds
  
  • Bianchi Massimo
  • Bossard Guillaume
  • Consoli Dario
  Journal of High Energy Physics, Springer, 2022, 2022 (6), pp.88. We analyse the perturbative four-point amplitudes in the simplest string theory examples of T-fold backgrounds, which enjoy N = 6 supersymmetries in four dimensions. There are two theories defined as asymmetric orbifolds of order 2 and 3, respectively. The perturbative spectrum and the one-loop four-point amplitudes are shown to be invariant under an arithmetic symplectic group defined over the Hurwitz (respectively Eisenstein) quaternions. The supersymmetry constraints on the low energy effective couplings are determined and we conjecture the U-duality group of the theory and the non-perturbative completion of the six-derivative coupling as a rank one theta series. We discuss the non-perturbative spectrum of BPS states in the light of our analysis. (10.1007/JHEP06(2022)088)
  DOI : 10.1007/JHEP06(2022)088
• Dynamical Mean-Field Theory of Moiré Bilayer Transition Metal Dichalcogenides: Phase Diagram, Resistivity, and Quantum Criticality
  
  • Zang Jiawei
  • Wang Jie
  • Cano Jennifer
  • Georges Antoine
  • Millis Andrew
  Physical Review X, American Physical Society, 2022, 12 (2), pp.021064. We present a comprehensive dynamical mean field study of the triangular lattice moiré Hubbard model, which is believed to represent the physics of moiré bilayer transition metal dichalcogenides. In these materials, important aspects of the band structure including the bandwidth and the order and location of van Hove singularities can be tuned by varying the interlayer potential. We present a magnetic and metal-insulator phase diagram and a detailed study of the dependence of the resistivity on temperature, band filling, and interlayer potential. We find that transport displays Fermi liquid, strange metal, and quantum critical behaviors in distinct regions of the phase diagram. Specifically, we find that the cube-root van Hove singularity [ρ(ε)∼|ε|−1/3] gives a strange metal behavior with a T-linear scattering rate and ω/T scaling. We show how magnetic order affects the resistivity. Our results elucidate the physics of the correlated states and the metal-insulator continuous transition recently observed in twisted homobilayer WSe2 and heterobilayer MoTe2/WSe2 experiments. (10.1103/PhysRevX.12.021064)
  DOI : 10.1103/PhysRevX.12.021064
• Strongly-correlated bosons in optical quasicrystals
  
  • Sanchez-Palencia Laurent
  , 2022.
• Coexisting charge density wave and ferromagnetic instabilities in monolayer InSe
  
  • Stepanov Evgeny
  • Harkov Viktor
  • Rösner Malte
  • Lichtenstein Alexander
  • Katsnelson Mikhail
  • Rudenko Alexander
  npj Computational Materials, Springer Nature, 2022, 8 (1), pp.118. Abstract Recently fabricated InSe monolayers exhibit remarkable characteristics that indicate the potential of this material to host a number of many-body phenomena. In this work, we systematically describe collective electronic effects in hole-doped InSe monolayers using advanced many-body techniques. To this end, we derive a realistic electronic-structure model from first principles that takes into account the most important characteristics of this material, including a flat band with prominent van Hove singularities in the electronic spectrum, strong electron–phonon coupling, and weakly screened long-ranged Coulomb interactions. We calculate the temperature-dependent phase diagram as a function of band filling and observe that this system is in a regime with coexisting charge density wave and ferromagnetic instabilities that are driven by strong electronic Coulomb correlations. This regime can be achieved at realistic doping levels and high enough temperatures, and can be verified experimentally. We find that the electron–phonon interaction does not play a crucial role in these effects, effectively suppressing the local Coulomb interaction without changing the qualitative physical picture. (10.1038/s41524-022-00798-4)
  DOI : 10.1038/s41524-022-00798-4
• Phenomenology of diphoton photoproduction at next-to-leading order
  
  • Grocholski Oskar
  • Pire Bernard
  • Sznajder Paweł
  • Szymanowski Lech
  • Wagner Jakub
  Physical Review D, American Physical Society, 2022, 105, pp.094025. We develop the analysis of diphoton exclusive photoproduction in the kinematics where a collinear QCD factorization framework applies, namely nearly forward large invariant mass diphoton production. We work at the leading twist level and at the next-to-leading order (NLO) in the strong coupling constant alpha_S. We compare our predictions for cross-sections with Born order calculations for the experimental conditions accessible to JLab experiments and show the interesting sensitivity of our results to various models of generalized parton distributions (GPDs). The NLO corrections are rather large and negative but do not prevent the studied reaction from being a promising tool for the extraction of C-dd GPDs, which do not contribute to either spacelike or timelike deeply virtual Compton scattering amplitudes.
• Asymptotically free solutions of the scalar mean field flow equations
  
  • Kopper Christoph
  Annales de l'Institut Henri Poincaré, Presses universitaires de France — PUF, 2022, 23, pp.3453-3492. The flow equations of the renormalisation group permit to analyse rigorously the perturbative n-point functions of renormalisable quantum field theories including gauge theories. In this paper we want to do a step towards a rigorous nonperturbative analysis of the flow equations (FEs). We restrict to massive scalar (one-component) fields and analyse a mean field limit where the Schwinger functions are considered to be momentum independent and thus are replaced by their zero momentum values. We analyse smooth solutions of the system of FEs for the n-point functions for different sets of boundary conditions. We will realise that allowing for nonvanishing irrelevant terms permits to construct asymptotically free nontrivial smooth solutions of the scalar field mean field FEs. (10.1007/s00023-022-01194-w)
  DOI : 10.1007/s00023-022-01194-w