Publications

2020

• Non-vanishing zero-temperature normal density in holographic superfluids
  
  • Goutéraux Blaise
  • Mefford Eric
  Journal of High Energy Physics, Springer, 2020, 11, pp.091. The low energy and finite temperature excitations of a d + 1-dimensional system exhibiting superfluidity are well described by a hydrodynamic model with two fluid flows: a normal flow and a superfluid flow. In the vicinity of a quantum critical point, thermodynamics and transport in the system are expected to be controlled by the critical exponents and by the spectrum of irrelevant deformations away from the quantum critical point. Here, using gauge-gravity duality, we present the low temperature dependence of thermodynamic and charge transport coefficients at first order in the hydrodynamic derivative expansion in terms of the critical exponents. Special attention will be paid to the behavior of the charge density of the normal flow in systems with emergent infrared conformal and Lifshitz symmetries, parameterized by a Lifshitz dynamical exponent z > 1. When 1 ≤ z < d + 2, we recover (z = 1) and extend (z > 1) previous results obtained by relativistic effective field theory techniques. Instead, when z > d + 2, we show that the normal charge density becomes non-vanishing at zero temperature. An extended appendix generalizes these results to systems that violate hyperscaling as well as systems with generalized photon masses. Our results clarify previous work in the holographic literature and have relevance to recent experimental measurements of the superfluid density on cuprate superconductors. (10.1007/JHEP11(2020)091)
  DOI : 10.1007/JHEP11(2020)091
• Bootstrapping boundary-localized interactions
  
  • Behan Connor
  • Di Pietro Lorenzo
  • Lauria Edoardo
  • van Rees Balt C.
  Journal of High Energy Physics, Springer, 2020, 2020 (12), pp.182. We study conformal boundary conditions for the theory of a single real scalar to investigate whether the known Dirichlet and Neumann conditions are the only possibilities. For this free bulk theory there are strong restrictions on the possible boundary dynamics. In particular, we find that the bulk-to-boundary operator expansion of the bulk field involves at most a ‘shadow pair’ of boundary fields, irrespective of the conformal boundary condition. We numerically analyze the four-point crossing equations for this shadow pair in the case of a three-dimensional boundary (so a four-dimensional scalar field) and find that large ranges of parameter space are excluded. However a ‘kink’ in the numerical bounds obeys all our consistency checks and might be an indication of a new conformal boundary condition. (10.1007/JHEP12(2020)182)
  DOI : 10.1007/JHEP12(2020)182
• Landau diagrams in AdS and S-matrices from conformal correlators
  
  • Komatsu Shota
  • Paulos Miguel F.
  • van Rees Balt C.
  • Zhao Xiang
  Journal of High Energy Physics, Springer, 2020, 2020 (46), pp.046. Quantum field theories in AdS generate conformal correlation functions on the boundary, and in the limit where AdS is nearly flat one should be able to extract an S-matrix from such correlators. We discuss a particularly simple position-space procedure to do so. It features a direct map from boundary positions to (on-shell) momenta and thereby relates cross ratios to Mandelstam invariants. This recipe succeeds in several examples, includes the momentum-conserving delta functions, and can be shown to imply the two proposals in [1] based on Mellin space and on the OPE data. Interestingly the procedure does not always work: the Landau singularities of a Feynman diagram are shown to be part of larger regions, to be called ‘bad regions’, where the flat-space limit of the Witten diagram diverges. To capture these divergences we introduce the notion of Landau diagrams in AdS. As in flat space, these describe on-shell particles propagating over large distances in a complexified space, with a form of momentum conservation holding at each bulk vertex. As an application we recover the anomalous threshold of the four-point triangle diagram at the boundary of a bad region. (10.1007/JHEP11(2020)046)
  DOI : 10.1007/JHEP11(2020)046
• Gapless and gapped holographic phonons
  
  • Amoretti Andrea
  • Areán Daniel
  • Goutéraux Blaise
  • Musso Daniele
  Journal of High Energy Physics, Springer, 2020, 2020, pp.058. We study a holographic model where translations are both spontaneously and explicitly broken, leading to the presence of (pseudo)-phonons in the spectrum. The weak explicit breaking is due to two independent mechanisms: a small source for the condensate itself and additional linearly space-dependent marginal operators. The low energy dynamics of the model is described by Wigner crystal hydrodynamics. In absence of a source for the condensate, the phonons remain gapless, but momentum is relaxed. Turning on a source for the condensate damps and pins the phonons. Finally, we verify that the universal relation between the phonon damping rate, mass and diffusivity reported in [1] continues to hold in this model for weak enough explicit breaking. (10.1007/JHEP01(2020)058)
  DOI : 10.1007/JHEP01(2020)058
• From Topological Superconductivity to Quantum Hall States in Coupled Wires
  
  • Yang Fan M
  • Perrin Vivien
  • Petrescu Alexandru
  • Garate Ion
  • Hur Karyn Le
  Physical Review B, American Physical Society, 2020. We present a theoretical study of the interplay between topological p-wave superconductivity, orbital magnetic fields and quantum Hall phases in coupled wire systems. First, we calculate the phase diagram and physical observables of a fermionic ladder made of two coupled Kitaev chains, and discuss the presence of two and four Majorana zero modes. Second, we analyze hybrid systems consisting of a Kitaev chain coupled to a Luttinger liquid. By tuning the magnetic field and the carrier density, we identify quantum Hall and charge density wave phases, as well as regimes in which superconductivity is induced in the second chain by proximity effect. Finally, we consider two-dimensional systems made of weakly coupled ladders. There, we engineer a $p+ip$ superconductor and describe a generalization of the $\nu=1/2$ fractional quantum Hall phase. These phases might be realized in solid-state or cold-atom nanowires. (10.1103/PhysRevB.101.085116)
  DOI : 10.1103/PhysRevB.101.085116
• Probing jet medium interactions via $Z(H)$ + jet momentum imbalances
  
  • Chen Lin
  • Wei Shu-Yi
  • Zhang Han-Zhong
  European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2020, 80 (12), pp.1136. Different types of high energy hard probes are used to extract the jet transport properties of the Quark-Gluon Plasma created in heavy-ion collisions, of which the heavy boson tagged jets are undoubtedly the most sophisticated due to its clean decay signature and production mechanism. In this study, we used the resummation improved pQCD approach with high order correction in the hard factor to calculate the momentum ratio $x_J$ distributions of Z and Higgs (H) tagged jets. We found that the formalism can provide a good description of the 5.02 TeV pp data. Using the BDMPS energy loss formalism, along with the OSU 2 + 1D hydro to simulate the effect of the medium, we extracted the value of the jet transport coefficient to be around ${\hat{q}}_0=4\sim 8~\text {GeV}^2/\text {fm}$ by comparing with the Z + jet PbPb experimental data. The H + jet $x_J$ distribution were calculated in a similar manner in contrast and found to have a stronger Sudakov effect as compared with the Z + jet distribution. This study uses a clean color-neutral boson as trigger to study the jet quenching effect and serves as a complimentary method in the extraction of the QGP’s transport coefficient in high energy nuclear collisions. (10.1140/epjc/s10052-020-08702-4)
  DOI : 10.1140/epjc/s10052-020-08702-4
• Weyl Connections and their Role in Holography
  
  • Ciambelli Luca
  • Leigh Robert G.
  Physical Review D, American Physical Society, 2020, 101 (8), pp.086020. It is a well-known property of holographic theories that diffeomorphism invariance in the bulk space-time implies Weyl invariance of the dual holographic field theory in the sense that the field theory couples to a conformal class of background metrics. The usual Fefferman-Graham formalism, which provides us with a holographic dictionary between the two theories, breaks explicitly this symmetry by choosing a specific boundary metric and a corresponding specific metric ansatz in the bulk. In this paper, we show that a simple extension of the Fefferman-Graham formalism allows us to sidestep this explicit breaking; one finds that the geometry of the boundary includes an induced metric and an induced connection on the tangent bundle of the boundary that is a Weyl connection (rather than the more familiar Levi-Civita connection uniquely determined by the induced metric). Properly invoking this boundary geometry has far-reaching consequences: the holographic dictionary extends and naturally encodes Weyl-covariant geometrical data, and, most importantly, the Weyl anomaly gains a clearer geometrical interpretation, cohomologically relating two Weyl-transformed volumes. The boundary theory is enhanced due to the presence of the Weyl current, which participates with the stress tensor in the boundary Ward identity. (10.1103/PhysRevD.101.086020)
  DOI : 10.1103/PhysRevD.101.086020
• Diffractive deeply virtual Compton scattering
  
  • Pire Bernard
  • Szymanowski Lech
  • Wallon Samuel
  Physical Review D, American Physical Society, 2020, 101 (7), pp.074005. Diffractive deeply virtual Compton scattering (DiDVCS) is the process $\gamma^*(- Q^2) + N \rightarrow \rho^0 + \gamma^* (Q'^2)+ N'$, where N is a nucleon or light nucleus, in the kinematical regime of large rapidity gap between the $\rho^0$ and the final photon-nucleus system, and in the generalized Bjorken regime where both photon virtualities $Q^2$ and $ Q'^2$ are large. We show that this process has the unique virtue of combining the large diffractive cross sections at high energy with the tomographic ability of deeply virtual Compton scattering to scrutinize the quark and gluon content of nucleons and light nuclei. Its study at an electron-ion collider will enlighten the internal structure of hadrons.
• The generalised infrared structure of the gluon propagator
  
  • Li Shirley Weishi
  • Lowdon Peter
  • Oliveira Orlando
  • Silva Paulo J.
  Physics Letters B, Elsevier, 2020, 803, pp.135329. Gauge theory correlators are potentially more singular in the infrared than those in non-gauge theories. We determine the implications that these singularities have on the spectrum of the theory, proving that the appearance of generalised poles implies the existence of on-shell states with fixed mass, but zero norm. For quantum chromodynamics these poles have direct relevance for the confinement of coloured states. Using lattice data for the Landau gauge gluon propagator we subsequently test for the presence of these poles, establishing that the data is indeed consistent with such a component. (10.1016/j.physletb.2020.135329)
  DOI : 10.1016/j.physletb.2020.135329
• $SO(3)$-invariant phase of the $O(N)^3$ tensor model
  
  • Benedetti Dario
  • Costa Ilaria
  Physical Review D, American Physical Society, 2020, 101 (8), pp.086021. We study classical and quantum (at large-N) field equations of bosonic tensor models with quartic interactions and O(N)3 symmetry. Among various possible patterns of spontaneous symmetry breaking we highlight an SO(3) invariant solution, with the tensor field expressed in terms of the Wigner 3jm symbol. We argue that such solution has a special role in the large-N limit, as in particular its scaling in N can provide an on-shell justification for the melonic large-N limit of the two-particle irreducible effective action in a broken phase. (10.1103/PhysRevD.101.086021)
  DOI : 10.1103/PhysRevD.101.086021
• Normal charge densities in quantum critical superfluids
  
  • Goutéraux Blaise
  • Mefford Eric
  Physical Review Letters, American Physical Society, 2020, 124 (16), pp.161604. The normal density of a translation-invariant superfluid often vanishes at zero temperature, as is observed in superfluid Helium and conventional superconductors described by BCS theory. Here we show that this need not be the case. We investigate the normal density in models of quantum critical superfluids using gauge-gravity duality. Models with an emergent infrared Lorentz symmetry lead to a vanishing normal density. On the other hand, models which break the isotropy between time and space may enjoy a nonvanishing normal density, depending on the spectrum of irrelevant deformations around the underlying quantum critical ground state. Our results may shed light on recent measurements of the superfluid density and low energy spectral weight in superconducting overdoped cuprates. (10.1103/PhysRevLett.124.161604)
  DOI : 10.1103/PhysRevLett.124.161604
• Generation of ultra-energetic ions by interaction of petawatt lasers with micrometer-scale foils
  
  • Héron A.
  • Adam J.-C.
  • Mora P.
  Physics of Plasmas, American Institute of Physics, 2020, 27 (1). The interaction of an ultraintense (2 × 1021 W/cm2) and ultrashort (18 fs) laser pulse with micrometer-scale aluminum foils is studied via the use of two and three dimensional (2D and 3D) particle-in-cell simulations. One shows that for a plane target with a steep density step, total (collisional and collisionless) absorption is weak. On the other hand, the use of structured targets (gratings in our case) or the presence of a sharp density gradient at the front of the slab allows a better coupling between the laser pulse and the target, and this yields a high absorption rate and ultraenergetic aluminum ions (in the 1 GeV range) generated by target normal sheath acceleration. By changing the characteristics of the grating, it is possible to control, to some extent, the absorption rate and the cutoff of the ion spectrum. It is also shown that a relatively simple model based on the adiabatic self-similar expansion of the target in the ultrarelativistic limit provides reasonable agreement with the simulation results. Finally, the comparison of 2D and 3D results for the interaction with gratings shows that 2D simulations accurately describe the absorption by 2D gratings but, on the other hand, they significantly overestimate the ion-spectrum cutoff. (10.1063/1.5127164)
  DOI : 10.1063/1.5127164
• Lieb-Liniger Bosons in a Shallow Quasiperiodic Potential: Bose Glass Phase and Fractal Mott Lobes
  
  • Yao Hepeng
  • Giamarchi Thierry
  • Sanchez-Palencia Laurent
  Physical Review Letters, American Physical Society, 2020, 125 (6), pp.060401. The emergence of a compressible insulator phase, known as the Bose glass, is characteristic of the interplay of interactions and disorder in correlated Bose fluids. While widely studied in tight-binding models, its observation remains elusive owing to stringent temperature effects. Here we show that this issue may be overcome by using Lieb-Liniger bosons in shallow quasiperiodic potentials. A Bose glass, surrounded by superfluid and Mott phases, is found above a critical potential and for finite interactions. At finite temperature, we show that the melting of the Mott lobes is characteristic of a fractal structure and find that the Bose glass is robust against thermal fluctuations up to temperatures accessible in quantum gases. Our results raise questions about the universality of the Bose glass transition in such shallow quasiperiodic potentials. (10.1103/PhysRevLett.125.060401)
  DOI : 10.1103/PhysRevLett.125.060401
• Photoproduction of three jets in the CGC: gluon TMDs and dilute limit
  
  • Altinoluk Tolga
  • Boussarie Renaud
  • Marquet Cyrille
  • Taels Pieter
  Journal of High Energy Physics, Springer, 2020, 07, pp.143. We study the process γA →$ q\overline{q}g $ + X in the Color Glass Condensate (CGC) effective theory. After obtaining the cross section, we consider two kinematic limits which are encompassed in our result. In the so-called correlation limit, the vector sum of the transverse momenta of the three outgoing particles is small with respect to the individual transverse momenta; the cross section then simplifies considerably and can be written in a factorized form, sensitive to both the unpolarized and linearly-polarized Weizsäcker-Williams transverse momentum dependent gluon distribution function (gluon TMD). The second limit of the CGC cross section that we consider is the dilute limit, which we obtain after performing a weak-field expansion; we recover a typical linear-regime expression, involving a single unintegrated gluon distribution function. Using numerical simulations of the small-x QCD evolution of the TMDs, we investigate the rapidity dependence of the cross section in the correlation limit. (10.1007/JHEP07(2020)143)
  DOI : 10.1007/JHEP07(2020)143
• Applications of Alpha Space
  
  • Rutter Daniel
  • van Rees Balt C.
  Journal of High Energy Physics, Springer, 2020, 2020 (12), pp.048. We extend the definition of ‘alpha space’ as introduced in [1] to two spacetime dimensions. We discuss how this can be used to find conformal block decompositions of known functions and how to easily recover several lightcone bootstrap results. In the second part of the paper we establish a connection between alpha space and the Lorentzian inversion formula of [2]. (10.1007/JHEP12(2020)048)
  DOI : 10.1007/JHEP12(2020)048
• Near Conformal Perturbation Theory in SYK Type Models
  
  • Das Sumit R.
  • Ghosh Animik
  • Jevicki Antal
  • Suzuki Kenta
  Journal of High Energy Physics, Springer, 2020, 12, pp.171. We present a systematic procedure to extract the dynamics of the low energy soft mode in SYK type models with a single energy scale J and emergent reparametrization symmetry in the IR. This is given in the framework of the perturbative scheme of arXiv:1608.07567 based on a specific (off-shell) breaking of conformal invariance in the UV, adjusted to yield the exact large-N saddle point. While this breaking term formally vanishes on-shell, it has a non-trivial effect on correlation functions and the effective action. In particular, it leads to the Schwarzian action with a specific coupling to bi-local matter. The method is applied to the evaluation of O(1) corrections to the correlation function of bi-locals. As a byproduct we confirm precise agreement with the explicit, symmetry breaking procedure. We provide a verification in the large q limit (Liouville theory), where the correlators can be calculated exactly at all length scales. In this case, our scheme illuminates how the enhanced O(J) and the subleading O(1) contributions originate from the Schwarzian dynamics of the soft mode and its interaction with h = 2 (bi-local) matter. (10.1007/JHEP12(2020)171)
  DOI : 10.1007/JHEP12(2020)171
• Fluid modelling of Stimulated Raman Scattering accounting for trapped particles benchmarked against fully kinetic simulations
  
  • Tran Guillaume
  • Loiseau Pascal
  • Fusaro A
  • Héron Anne
  • Hüller Stefan
  • Maëder L
  • Masson-Laborde P.-E
  • Penninckx Denis
  • Riazuelo G
  Physics of Plasmas, American Institute of Physics, 2020, 27 (12), pp.122707. A new fluid model describing backward stimulated Raman scattering (SRS) is presented based on parametric three-wave coupling in multidimensional geometry. It takes into account kinetic effects in the description of the plasma wave via a non linear frequency shift due to trapped electrons. The model is valid in the regime of hot and weakly inhomogeneous plasmas under conditions relevant for inertial confinement fusion with the plasma parameter k L λ De 0.25 (k L standing for the plasma wave number and λ De for the Debye length). Benchmarks of the model have been performed against the Maxwell-particle-in-cell (PIC) code Emi2D in order to calibrate the adjustable parameters controlling the non linear frequency shift. Two major configurations have been tested, one in a homogeneous plasma, with the onset of laser pump depletion and the other in an inhomogeneous plasma, producing auto-resonant growth. Good agreement between fluid and PIC simulations has been found for both configurations, in particular for the growth of SRS, and further on in time for the average backscatter level. The model is a promising tool to be implemented in multi-dimensional laser-plasma interaction packages coupled to hydrodynamics codes in order to compute SRS in mm-size volumes, usually inaccessible with PIC codes. (10.1063/5.0018669)
  DOI : 10.1063/5.0018669
• Analytic constraints on the energy-momentum tensor in conformal field theories
  
  • Lorcé Cédric
  • Lowdon Peter
  Physical Review D, American Physical Society, 2020, 102, pp.125013. In this work we investigate the matrix elements of the energy-momentum tensor for massless on-shell states in four-dimensional unitary, local, and Poincar\'e covariant quantum field theories. We demonstrate that these matrix elements can be parametrised in terms of covariant multipoles of the Lorentz generators, and that this gives rise to a form factor decomposition in which the helicity dependence of the states is factorised. Using this decomposition we go on to explore some of the consequences for conformal field theories, deriving the explicit analytic conditions imposed by conformal symmetry, and using examples to illustrate that they uniquely fix the form of the matrix elements. We also provide new insights into the constraints imposed by the existence of massless particles, showing in particular that massless free theories are necessarily conformal. (10.1103/PhysRevD.102.125013)
  DOI : 10.1103/PhysRevD.102.125013
• J/ψ meson production in SIDIS: matching high and low transverse momentum
  
  • Boer Daniël
  • d'Alesio Umberto
  • Murgia Francesco
  • Pisano Cristian
  • Taels Pieter
  Journal of High Energy Physics, Springer, 2020, 09, pp.040. We consider the transverse momentum spectrum and the cos 2ϕ azimuthal distribution of J/ψ mesons produced in semi-inclusive, deep-inelastic electron-proton scattering, where the electron and the proton are unpolarized. At low transverse momentum, we propose factorized expressions in terms of transverse momentum dependent gluon distributions and shape functions. We show that our formulae, at the order α$_{s}$, correctly match with the collinear factorization results at high transverse momentum. The latter are computed at the order $ {\alpha}_s^2 $ in the framework of nonrelativistic QCD (NRQCD), with the inclusion of the intermediate $ {}^3{S}_1^{\left[1\right]} $ color-singlet Fock state, as well as the subleading color-octet ones that are relatively suppressed by a factor v$^{4}$ in the NRQCD velocity parameter v. We show that the $ {}^1{S}_0^{\left[8\right]} $ and $ {}^3{P}_J^{\left[8\right]} $ (J = 0, 1, 2) contributions diverge in the small transverse momentum region and allow us to determine the perturbative tails of the shape functions, which carry the same quantum numbers. These turn out to be identical, except for the overall magnitude given by the appropriate NRQCD long distance matrix element. (10.1007/JHEP09(2020)040)
  DOI : 10.1007/JHEP09(2020)040
• On the stability of open-string orbifold models with broken supersymmetry
  
  • Abel Steven
  • Coudarchet Thibaut
  • Partouche Hervé
  Nuclear Physics B, North-Holland ; Elsevier [1967-....], 2020, 957, pp.115100. We consider an open-string realisation of N=2→N=0 spontaneous breaking of supersymmetry in four-dimensional Minkowski spacetime. It is based on type IIB orientifold theory compactified on T2×T4/Z2 , with Scherk–Schwarz supersymmetry breaking implemented along T2 . We show that in the regions of moduli space where the supersymmetry breaking scale is lower than the other scales, there exist configurations with minima that have massless Bose-Fermi degeneracy and hence vanishing one-loop effective potential, up to exponentially suppressed corrections. These backgrounds describe non-Abelian gauge theories, with all open-string moduli and blowing up modes of T4/Z2 stabilized, while all untwisted closed-string moduli remain flat directions. Other backgrounds with strictly positive effective potentials exist, where the only instabilities arising at one loop are associated with the supersymmetry breaking scale, which runs away. All of these backgrounds are consistent non-perturbatively. (10.1016/j.nuclphysb.2020.115100)
  DOI : 10.1016/j.nuclphysb.2020.115100
• Universality of the Poincaré gravitational form factor constraints
  
  • Lorcé Cédric
  • Lowdon Peter
  European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2020, 80 (3), pp.207. Relativistic spin states are convention dependent. In this work we prove that the zero momentum-transfer limits of the leading two form factors in the decomposition of the energy–momentum tensor matrix elements are independent of this choice. In particular, we demonstrate that these constraints are insensitive to whether the corresponding states are massive or not, and that they arise purely due to the Poincaré covariance of the states. (10.1140/epjc/s10052-020-7779-z)
  DOI : 10.1140/epjc/s10052-020-7779-z
• 1/8-BPS Couplings and Exceptional Automorphic Functions
  
  • Bossard Guillaume
  • Kleinschmidt Axel
  • Pioline Boris
  SciPost Physics, SciPost Foundation, 2020, 8 (4), pp.054. Unlike the $R^4$ and $\nabla^4 R^4$ couplings, whose coefficients are Langlands--Eisenstein series of the U-duality group, the coefficient $\mathcal{E}^{(d)}_{(0,1)}$ of the $\nabla^6 R^4$ interaction in the low-energy effective action of type II strings compactified on a torus $T^d$ belongs to a more general class of automorphic functions, which satisfy Poisson rather than Laplace-type equations. In earlier work, it was proposed that the exact coefficient is given by a two-loop integral in exceptional field theory, with the full spectrum of mutually 1/2-BPS states running in the loops, up to the addition of a particular Langlands--Eisenstein series. Here we compute the weak coupling and large radius expansions of these automorphic functions for any $d$. We find perfect agreement with perturbative string theory up to genus three, along with non-perturbative corrections which have the expected form for 1/8-BPS instantons and bound states of 1/2-BPS instantons and anti-instantons. The additional Langlands--Eisenstein series arises from a subtle cancellation between the two-loop amplitude with 1/4-BPS states running in the loops, and the three-loop amplitude with mutually 1/2-BPS states in the loops. For $d=4$, the result is shown to coincide with an alternative proposal in terms of a covariantised genus-two string amplitude, due to interesting identities between the Kawazumi--Zhang invariant of genus-two curves and its tropical limit, and between double lattice sums for the particle and string multiplets, which may be of independent mathematical interest. (10.21468/SciPostPhys.8.4.054)
  DOI : 10.21468/SciPostPhys.8.4.054
• Medium-Induced Transverse Momentum Broadening via Forward Dijet Correlations
  
  • Jia Jiangyong
  • Wei Shu-Yi
  • Xiao Bo-Wen
  • Yuan Feng
  Phys.Rev.D, 2020, 101 (9), pp.094008. Dijet azimuthal angle correlation is arguably one of the most direct probes of the medium-induced broadening effects. The evidence for such broadening, however, is not yet clearly observed within the precision of current midrapidity measurements at RHIC and the LHC. We show that the dijet correlation in forward rapidity from the future LHC RUN3, aided by forward detector upgrades, can reveal this broadening thanks to the steeper jet spectra, suppressed vacuum radiations and lower underlying event background, with a sensitivity comparable to that of the future high-luminosity Au+Au run at RHIC. Dijet correlation measurements at the two facilities together can provide powerful constraints on the temperature dependence of medium transport properties. (10.1103/PhysRevD.101.094008)
  DOI : 10.1103/PhysRevD.101.094008
• Supersymmetric Rényi entropy and charged hyperbolic black holes
  
  • Hosseini Seyed Morteza
  • Toldo Chiara
  • Yaakov Itamar
  Journal of High Energy Physics, Springer, 2020, 07, pp.131. (10.1007/JHEP07(2020)131)
  DOI : 10.1007/JHEP07(2020)131
• Particle-number distribution in large fluctuations at the tip of branching random walks
  
  • Mueller A.H.
  • Munier S.
  Physical Review E, American Physical Society (APS), 2020, 102 (2), pp.022104. We investigate properties of the particle distribution near the tip of one-dimensional branching random walks at large times t, focusing on unusual realizations in which the rightmost lead particle is very far ahead of its expected position, but still within a distance smaller than the diffusion radius ∼t. Our approach consists in a study of the generating function GΔx(λ)=∑nλnpn(Δx) for the probabilities pn(Δx) of observing n particles in an interval of given size Δx from the lead particle to its left, fixing the position of the latter. This generating function can be expressed with the help of functions solving the Fisher-Kolmogorov-Petrovsky-Piscounov (FKPP) equation with suitable initial conditions. In the infinite-time and large-Δx limits, we find that the mean number of particles in the interval grows exponentially with Δx, and that the generating function obeys a nontrivial scaling law, depending on Δx and λ through the combined variable [Δx−f(λ)]3/Δx2, where f(λ)≡−ln(1−λ)−ln[−ln(1−λ)]. From this property, one may conjecture that the growth of the typical particle number with the size of the interval is slower than exponential, but, surprisingly enough, only by a subleading factor at large Δx. The scaling we argue is consistent with results from a numerical integration of the FKPP equation. (10.1103/PhysRevE.102.022104)
  DOI : 10.1103/PhysRevE.102.022104