The “imaging-by-smashing” technique <cross-ref refid='br0010' id='crf0090'>[1]</cross-ref> has been developed recently in relativistic nuclear collisions. By smashing heavy nuclei at RHIC and the LHC and analysing the anisotropic expansion (flow) of the final state produced particles, unique information on the structure of the collided nuclei can be obtained. Existing efforts primarily focus on the colliding mode of heavy nuclei collisions. In contrast, nuclear structure studies with collisions of light nuclei and the fixed target mode have not been thoroughly explored despite their significant impact and broad interest. In this Letter, we investigate the nuclear structure of 20Ne and 16O in the fixed-target 208Pb&#8211; 20Ne and 208Pb&#8211; 16O collisions at <math altimg='si1.svg'><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><msub><mrow /><mrow><mi mathvariant='normal'>NN</mi></mrow></msub></mrow></msub></mrow></msqrt></math> = 68.5 GeV, using the parton transport model AMPT. The results of two- and four-particle cumulants of anisotropic flow demonstrate a robust signature of nuclear structure effect that persists regardless of the complex dynamic evolution of the created systems. The comparison to the recent hydrodynamic calculations reveals a new possibility of uncovering the origins of collective flow in small systems. This study highlights the significant impact of the light nuclei collisions at the LHCb SMOG (SMOG2) project.

China

Denmark

Zhiyong Lu

Mingrui Zhao

Emil Gorm Dahlbæk Nielsen

Xiaomei Li

You Zhou

Imprint of light nuclei structure in relativistic nuclear collisions

In this study, we investigate the $R^2$ corrections to the dissociation of heavy quarkonium in the Gauss-Bonnet gravitational background. We analyze the impact of the Gauss-Bonnet parameter $\lambda_{\rm GB}$ on the spectral function of charmonium and bottomonium and examine the effect of $\lambda_{\rm GB}$ on the dissociation of heavy quarkonium. Our results show that $\lambda_{\rm GB}$ reduces the peak height and increases the peak width of the spectral function, suggesting that $\lambda_{\rm GB}$ enhances the dissociation of heavy quarkonium. We also discuss the variation in the dissociation of heavy quarkonium with the ratio of shear viscosity to entropy density and observe that the dissociation is easier in more perfect plasma. Additionally, we observe that the temperature decreases the peak height and widens the peak, thereby accelerating the dissociation.

Zhou-Run Zhu

Manman Sun

Rui Zhou

Jinzhong Han

$\textit{R}$ $^{2}$ corrections to holographic heavy quarkonium dissociation * Rui Zhou supported by the Science and Technology Development Plan Project of Henan Province, China (242102230085), the National Natural Science Foundation of China (12404470), the High Level Talents Research and Startup Foundation Projects for Doctors of Zhoukou Normal University, China (ZKNUC2023017). Manman Sun supported by the National Natural Science Foundation of China (12305076). Zhou-Run Zhu supported by the High Level Talents Research and Startup Foundation Projects for Doctors of Zhoukou Normal University, China (ZKNUC2023018)

For the Laplacian of an n-Riemannian manifold X, the Weyl law states that the k-th eigenvalue is asymptotically proportional to (k/V)2/n , where V is the volume of X. We show that this result can be derived via physical considerations by demanding that the gravitational potential for a compactification on X behaves in the expected (4+n)-dimensional way at short distances. In simple product compactifications, when particle motion on X is ergodic, for large k the eigenfunctions oscillate around a constant, and the argument is relatively straightforward. The Weyl law thus allows to reconstruct the four-dimensional Planck mass from the asymptotics of the masses of the spin 2 Kaluza-Klein modes. For warped compactifications, a puzzle appears: the Weyl law still depends on the ordinary volume V, while the Planck mass famously depends on a weighted volume obtained as an integral of the warping function. We resolve this tension by arguing that in the ergodic case the eigenfunctions oscillate now around a power of the warping function rather than around a constant, a property that we call weighted quantum ergodicity. This has implications for the problem of gravity localization, which we discuss. We show that for spaces with Dp-brane singularities the spectrum is discrete only for p = 6, 7, 8, and for these cases we rigorously prove the Weyl law by applying modern techniques from RCD theory.

United States

G. Luca

Italy

Nicolò Ponti

United Kingdom

Andrea Mondino

Alessandro Tomasiello

Can you hear the Planck mass?

Machine learning-based jet classifiers are able to achieve impressive tagging performance in a variety of applications in high-energy and nuclear physics. However, it remains unclear in many cases which aspects of jets give rise to this discriminating power, and whether jet observables that are tractable in perturbative QCD such as those obeying infrared-collinear (IRC) safety serve as sufficient inputs. In this article, we introduce a new classifier, Jet Flow Networks (JFNs), in an effort to address the question of whether IRC unsafe information provides additional discriminating power in jet classification. JFNs are permutation-invariant neural networks (deep sets) that take as input the kinematic information of reconstructed subjets. The subjet radius and a cut on the subjet’s transverse momenta serve as tunable hyperparameters enabling a controllable sensitivity to soft emissions and nonperturbative effects. We demonstrate the performance of JFNs for quark vs. gluon and Z vs. QCD jet tagging. For small subjet radii and transverse momentum cuts, the performance of JFNs is equivalent to the IRC-unsafe Particle Flow Networks (PFNs), demonstrating that infrared-collinear unsafe information is not necessary to achieve strong discrimination for both cases. As the subjet radius is increased, the performance of the JFNs remains essentially unchanged until physical thresholds that we identify are crossed. For relatively large subjet radii, we show that the JFNs may offer an increased model independence with a modest tradeoff in performance compared to classifiers that use the full particle information of the jet. These results shed new light on how machines learn patterns in high-energy physics data.

Dimitrios Athanasakos

Andrew Larkoski

James Mulligan

Mateusz Płoskoń

Felix Ringer

Is infrared-collinear safe information all you need for jet classification?

The identification of interesting substructures within jets is an important tool for searching for new physics and probing the Standard Model at colliders. Many of these substructure tools have previously been shown to take the form of optimal transport problems, in particular the Energy Mover’s Distance (EMD). In this work, we show that the EMD is in fact the natural structure for comparing collider events, which accounts for its recent success in understanding event and jet substructure. We then present a Shape Hunting Algorithm using Parameterized Energy Reconstruction (Shaper), which is a general framework for defining and computing shape-based observables. Shaper generalizes N-jettiness from point clusters to any extended, parametrizable shape. This is accomplished by efficiently minimizing the EMD between events and parameterized manifolds of energy flows representing idealized shapes, implemented using the dual-potential Sinkhorn approximation of the Wasserstein metric. We show how the geometric language of observables as manifolds can be used to define novel observables with built-in infrared-and-collinear safety. We demonstrate the efficacy of the Shaper framework by performing empirical jet substructure studies using several examples of new shape-based observables.

Demba Ba

Akshunna Dogra

Rikab Gambhir

Abiy Tasissa

Jesse Thaler

SHAPER: can you hear the shape of a jet?

Anisotropic flow, typically defined as the azimuthal correlations of the produced particles with respect to the common symmetry plane over a large kinematic, has been a popular approach in the last three decades to explore the properties of hot and dense QCD matter in high-energy heavy-ion collisions. These flow studies are usually based on the multi-particle correlations method, assuming that multi-particle correlations can be factorized into the product of flow coefficients. However, recent LHC measurements, based on new four-particle correlation observables, show evidence of flow angle decorrelation and flow magnitude decorrelation. These decorrelations break the assumption of the common symmetry plane and factorization. In this paper, we perform systematic studies to investigate the decorrelation with A Multi-Phase Transport (AMPT) model. We examine different tunings of the initial conditions, partonic cross sections, and hadronic interactions, revealing that the decorrelations are mainly driven by the initial geometry fluctuations while weakly influenced by the system’s dynamic evolution. Comparison to experimental data and the AMPT calculations presented in this paper promotes a new possibility to further constraints on the initial conditions of the heavy-ion collisions.

Emil Nielsen

Transverse momentum decorrelation of the flow vector in Pb–Pb collisions at $$\sqrt{s_{_{\textrm{NN}}}}$$ <math> <msqrt> <msub> <mi>s</mi> <msub> <mrow></mrow> <mtext>NN</mtext> </msub> </msub> </msqrt> </math> = 5.02 TeV

We propose that the nature of indirect signals of dark matter (DM) can depend on the Galactic environment they originate from. We demonstrate this possibility in models where DM annihilates into light mediators whose branching fractions depend on a long-range force sourced by ordinary matter. In particular, electromagnetic signals of DM may only arise near the centers of galaxies where the ordinary matter densities, and hence astrophysical background levels, are high. We briefly discuss how our model could explain the Galactic Center gamma ray excess, without leaving much of a trace in baryon-poor environments, like dwarf spheroidal galaxies. Similar spatial dependence of indirect signals can also apply to models featuring metastable DM decay into light mediators.

Hooman Davoudiasl

Julia Gehrlein

Indirect signals of dark matter can change depending on where you look

We study the overshoot problem in the context of post-inflationary string cosmology (in particular LVS). LVS cosmology features a long kination epoch as the volume modulus rolls down the exponential slope towards the final minimum, with an energy density that scales as <math> <msubsup> <mi>m</mi> <mi>s</mi> <mn>4</mn> </msubsup> </math> $$ {m}_s^4 $$ . It is a known fact that such a roll admits attractor tracker solutions, and if these are located the overshoot problem is solved. We show that, provided a sufficiently large hierarchy exists between the inflationary scale and the weak scale, this will always occur in LVS as initial seed radiation grows into the tracker solution. The consistency requirement of ending in a stable vacuum containing the weak hierarchy therefore gives a preference for high inflationary scales — an anthropic argument, if one likes, for a large inflation/weak hierarchy. We discuss various origins, both universal and model-dependent, of the initial seed radiation (or matter). One particularly interesting case is that of a fundamental string network arising from brane inflation — this may lead to an early epoch in which the universe energy density principally consists of gravitational waves, while an LVS fundamental string network survives into the present universe.

Joseph Conlon

Filippo Revello

Catch-me-if-you-can: the overshoot problem and the weak/inflation hierarchy

A special class of four-point correlation functions in the maximally supersymmetric Yang-Mills theory is given by the square of the Fredholm determinant of a generalized Bessel kernel. In this note, we re-express its logarithmic derivatives in terms of a two-dimensional Riemann-Hilbert problem. We solve the latter in the null limit making use of the Deift-Zhou steepest descent. We reproduce the exact octagonal anomalous dimension in 't Hooft coupling and provide its novel formulation as the convolution of a non-linear quasiclassical phase with the Fermi distribution in the limit of the infinite chemical potential.

A.V. Belitsky

Null octagon from Deift-Zhou steepest descent

In this manuscript, we report the outcome of the topical workshop: paving the way to alternative NNLO strategies ( https://indico.ific.uv.es/e/WorkStop-ThinkStart_3.0  ), by presenting a discussion about different frameworks to perform precise higher-order computations for high-energy physics. These approaches implement novel strategies to deal with infrared and ultraviolet singularities in quantum field theories. A special emphasis is devoted to the local cancellation of these singularities, which can enhance the efficiency of computations and lead to discover novel mathematical properties in quantum field theories.

Germany

Spain

W. Torres Bobadilla

G. Sborlini

Switzerland

P. Banerjee

S. Catani

Brazil

A. Cherchiglia

L. Cieri

P. Dhani

F. Driencourt-Mangin

T. Engel

G. Ferrera

C. Gnendiger

Mexico

R. Hernández-Pinto

Portugal

B. Hiller

G. Pelliccioli

J. Pires

R. Pittau

M. Rocco

G. Rodrigo

M. Sampaio

A. Signer

C. Signorile-Signorile

D. Stöckinger

F. Tramontano

Y. Ulrich

May the four be with you: novel IR-subtraction methods to tackle NNLO calculations