Nuclear Theory·nucl-th

Monday·March 31, 2025

13 papers—5 primary·8 cross-listed

06
Small radius inclusive jet production at the LHC through NNLO+NNLL
Terry Generet🇬🇧 · Kyle Lee🇺🇸 · Ian Moult🇺🇸 · Rene Poncelet🇵🇱 · Xiaoyuan Zhang🇺🇸
The study of hadronic jets and their substructure at hadronic colliders is crucial for improving our understanding of QCD, and searching for new physics. As such, there has been a significant effort to improve their theoretical description. In the small radius limit, inclusive jet production exhibits a universal factorization, enabling the resummation of logarithms which greatly stabilizes theoretical predictions. In this paper, we show how to combine a recently introduced framework for small- $R$ resummation with the STRIPPER subtraction formalism for fragmentation, enabling next-to-next-to-leading order calculations of small- $R$ inclusive jet production for a wide variety of processes at the LHC. We extract the two-loop constants for the jet functions, enabling for the first time next-to-next-to-leading logarithmic resummation matched to next-to-next-to-leading order perturbative calculation. We compare with CMS data for small- $R$ jet production, and find that our results greatly improve the accuracy of the predictions at small- $R$ , and stabilize the perturbative convergence and error estimates at larger $R$ . Our approach is applicable to a wide class of jet substructure observables exhibiting similar factorization theorems, opening the door to an NNLO jet substructure program at the LHC.
↳ hep-phhep-exnucl-thJHEP(2025)·12 citations
07
Visualizing How Jet Structure Shapes Jet Wakes
Arjun Srinivasan Kudinoor🇺🇸 · Daniel Pablos🇪🇸 · Krishna Rajagopal🇺🇸
The ATLAS Collaboration has developed a method to analyze large-radius jets composed of skinny $R = 0.2$ subjets in heavy-ion collisions. We first demonstrate that the measurements pioneered by ATLAS constrain the value of $L_{res}$ , the resolution length of QGP -- and rule out any picture in which an entire parton shower loses energy coherently as a single entity. We then analyze the response of the medium to the passage of large-radius $R = 2$ jets containing two skinny subjets in gamma-jet events. We introduce novel jet-shape observables that allow us to visualize how the internal structure of large-radius jets shapes the wakes they excite in the QGP. We find that even when the subjets are $\sim 0.8$ radians apart, the angular shape of the soft hadrons originating from their wake forms a single broad structure. Only when the two subjets are even farther apart are two sub-wakes revealed. We show that the way in which jet structure shapes the structure of jet-induced wakes can be visualized with similar clarity in experiments by using only low- $p_{T}$ hadrons. The observables we introduce offer a new and distinctive way of seeing jet-induced wakes -- and wake substructure -- in heavy-ion collision data.
↳ hep-phnucl-exnucl-thEPJ Web Conf.(2025)·1 citation
08
Spinor Representations for Fields with any Spin: Lorentz Tensor Basis for Operators and Covariant Multipole Decomposition
Wim Cosyn🇺🇸 · Frank Vera🇺🇸
This paper discusses a framework to parametrize and decompose operator matrix elements for particles with higher spin $(j > 1/2)$ using chiral representations of the Lorentz group, i.e. the $(j, 0)$ and $(0, j)$ representations and their parity-invariant direct sum. Unlike traditional approaches that require imposing constraints to eliminate spurious degrees of freedom, these chiral representations contain exactly the $2 j + 1$ components needed to describe a spin- $j$ particle. The central objects in the construction are the $t$ -tensors, which are generalizations of the Pauli four-vector $σ^{μ}$ for higher spin. For the generalized spinors of these representations, we demonstrate how the algebra of the $t$ -tensors allows to formulate a generalization of the Dirac matrix basis for any spin. For on-shell bilinears, we show that a set consisting exclusively of covariant multipoles of order $0 \leq m \leq 2 j$ forms a complete basis. We provide explicit expressions for all bilinears of the generalized Dirac matrix basis, which are valid for any spin value. As a byproduct of our derivations we present an efficient algorithm to compute the $t$ -tensor matrix elements. The formalism presented here paves the way to use a more unified approach to analyze the non-perturbative QCD structure of hadrons and nuclei across different spin values, with clear physical interpretation of the resulting distributions as covariant multipoles.
↳ hep-phhep-thnucl-thJHEP(2025)·2 citations
09
Crystalline Phases in QCD
Theo F. Motta🇩🇪
For decades now, low-energy models of QCD have shown indications that a crystalline quark phase could be stable at high chemical potentials. Beyond models, however, there are numerous difficulties in investigating such a hypothesis in full QCD, such as the sign problem. Functional methods do not suffer from the sign problem, and thus, can access the high-- $μ$ side of the QCD phase diagram. The main tool used to look for signs of inhomogeneous/crystalline phases in low-energy models is the so-called ``stability analysis''. In this talk, I show how the standard stability analysis was generalised to be applicable in any theory, including QCD.
↳ hep-phhep-thnucl-thPoS(2025)·0 citations
10
SU(3) centre vortex geometry at finite temperature
Jackson A. Mickley🇦🇺 · Waseem Kamleh🇦🇺 · Derek B. Leinweber🇦🇺
The importance of examining the structure of centre-vortex matter in the ground-state fields of nonabelian gauge-field theory has been demonstrated in the recent centre-vortex based discovery of a second finite-temperature transition in QCD associated with quark deconfinement. This signals the presence of a new phase of ground-state field structure between the well separated chiral and deconfinement transitions. In this short presentation, we re-examine pure SU(3) gauge theory which provides a foundation for the development of techniques for the examination of full QCD. This time, we reconsider visualisations of the centre-vortex structure in light of the quantitative analysis that demonstrates the first order nature of the deconfinement phase transition in the pure-gauge theory. Here we consider a detailed side-by-side comparison of the field structure slightly below and slightly above the critical temperature. The abrupt changes of the field structure in the first order phase transition are easy to observe in the representative visualisations.
↳ hep-lathep-thnucl-thPoS(2025)·0 citations
11
Studying the $K Λ$ strong interaction with femtoscopic correlation functions and the $N^{*} (1535)$
Si-Wei Liu🇨🇳 · Ju-Jun Xie🇨🇳
We investigate the $K Λ$ strong interaction dynamics around the energy region of $N^{*} (1535)$ resonance through femtoscopic correlation functions within the Koonin-Pratt formalism, where coupled-channel effects of $π N$ , $K Λ$ , $K Σ$ and $η N$ channels are taken into account, by means of which the $N^{*} (1535)$ resonance can be dynamically generated in the chiral unitary approach. Two-body scattering amplitudes are calculated using the chiral unitary approach, and the corresponding wave functions and correlation functions are obtained. Our analysis shows that the $π N$ channel becomes important to the $K^{+} Λ$ correlation function through coupled channel effects, even if its mass threshold is far from the energy region of the $N^{*} (1535)$ . Furthermore, with the picture that the $N^{*} (1535)$ is a dynamically generated state, we can get a good reproduction of the experimental data on the $K^{+} Λ$ correlation function. This work establishes femtoscopic correlation functions as a sensitive probe for coupled-channel dynamics and validates the Koonin-Pratt framework in multi-channel hadronic systems, offering critical insights into some exotic hadron states and strong interaction mechanisms.
↳ hep-phnucl-thPRD(2025)·12 citations
12
Spin Polarization of $Λ$ hyperons from Dissipative Spin Hydrodynamics
Sapna🇮🇳 · Sushant K. Singh🇮🇹 · David Wagner🇮🇹
We present a framework for spin dynamics in the quark-gluon plasma created in relativistic heavy-ion collisions. Under the approximation of small polarization, macroscopic spin degrees of freedom decouple from the background, and their evolution equations and transport coefficients have been computed using quantum kinetic theory of massive particles with nonlocal collisions. Employing this theory, we numerically solve dissipative relativistic spin hydrodynamics. We explore three interaction scenarios between constituent particles and apply this framework to compute both global and local spin polarization of $Λ$ hyperons in Au+Au collisions at $s_{N N} = 200$ GeV. Our results show that the initially vanishing spin potential relaxes toward thermal vorticity, driving global polarization. Furthermore, we demonstrate that the sign of longitudinal polarization is sensitive to the interaction type, emphasizing the need for a consistent treatment of dissipative effects in spin hydrodynamics to describe experimental data.
↳ hep-phnucl-thPRC(2025)·29 citations
13
Towards a Quantum Information Theory of Hadronization: Dihadron Fragmentation and Neutral Polarization in Heavy Baryons
Rebecca von Kuk🇩🇪 · Kyle Lee🇺🇸 · Johannes K. L. Michel🇳🇱 · Zhiquan Sun🇺🇸
We pioneer the application of quantum information theory to experimentally distinguish between classes of hadronization models. We adapt the CHSH inequality to the fragmentation of a single parton to hadron pairs, a violation of which would rule out classical dynamics of hadronization altogether. Furthermore, we apply and extend the theory of quantum contextuality and local quantum systems to the neutral polarization of a single spin-1 hadronic system, namely the light constituents of excited Sigma baryons $Σ_{c, b}^{*}$ formed in the fragmentation of heavy quarks.
↳ hep-phhep-exnucl-exnucl-th+124 citations

Affiliations

first authorsco-authorsvia INSPIRE