Nuclear Theory·nucl-th

Monday·May 19, 2025

7 papers—4 primary·3 cross-listed

05
Distribution Functions of $Λ$ and $Σ^{0}$ Baryons
Yang Yu🇨🇳 · Peng Cheng🇨🇳 · Hui-Yu Xing🇨🇳 · Daniele Binosi🇮🇹 · Craig D. Roberts🇨🇳
Treating baryons as quark + interacting-diquark bound states, a symmetry-preserving formulation of a vector $\times$ vector contact interaction (SCI) is used to deliver an extensive, coherent set of predictions for $Λ, Σ^{0}$ baryon unpolarised and polarised distribution functions (DFs) -- valence, glue, and four-flavour separated sea -- and compare them with those of a like-structured nucleon. $Λ, Σ^{0}$ baryons are strangeness negative-one isospin partners within the SU $(3)$ -flavour baryon octet. This makes such structural comparisons significant. The study reveals impacts of diquark correlations and SU $(3)$ -flavour symmetry breaking on $Λ$ , $Σ^{0}$ structure functions, some of which are significant. For instance, were it not for the presence of axialvector diquarks in the $Σ^{0}$ at the hadron scale, the $s$ quark could carry none of the $Σ^{0}$ spin. The discussion canvasses issues that include helicity retention in hard scattering processes; the sign and size of polarised gluon DFs; and the origin and decomposition of baryon spins. Interpreted judiciously, the SCI analysis delivers an insightful explanation of baryon structure as expressed in DFs.
↳ hep-phhep-exhep-latnucl-ex+1EPJA(2025)·8 citations
06
Some Aspects of Three-Quark Potentials (Part II)
Oleg Andreev🇩🇪
We continue our investigation of the effective string model for the triply heavy quark system, mimicking that in pure $S U (3)$ gauge theory. We present analytical and numerical studies of the three-quark potential for isosceles and collinear geometries. In the general case, we derive the asymptotic expression of the potential in the infrared limit. Here we also demonstrate the universality of the string tension and interpret the transition between two distinct regimes, occurring when one of the triangle's angles formed by the quarks is equal to $\frac{2}{3} π$ , as a breaking of permutational symmetry. This symmetry breaking implies the emergence of a heavy quark dressed by gluons, transforming in the two-index antisymmetric representation. Additionally, we discuss various aspects of the $Y$ - and $Δ$ -laws, diquarks, and connections to lattice QCD.
↳ hep-phhep-lathep-thnucl-thPRD(2025)·3 citations
07
Thermal Static Potential and Pseudo-Scalar Quarkonium Spectral Functions from 2+1 Flavor Lattice QCD
Sajid Ali🇩🇪 · Dibyendu Bala🇩🇪 · Olaf Kaczmarek🇩🇪 · Pavan🇩🇪
Quarkonia, which are bound states of a heavy quark and antiquark, play a key role in probing the quark-gluon plasma (QGP). The dynamics of quarkonia in the QGP are encoded in their finite-temperature spectral functions. In this work, we estimate the quarkonium spectral functions in the pseudo-scalar channel using 2+1 flavor lattice QCD with a pion mass of $320 MeV$ , at temperatures of $220 MeV (1.2 T_{p c}), 251 MeV (1.4 T_{p c}) and 293 MeV (1.6 T_{p c})$ . Reconstructing the spectral function from the Euclidean lattice correlator is a well-known ill-posed problem, requiring additional physics-motivated input. We address this by smoothly matching contributions from different frequency regions of the spectral function, using appropriate physics valid for each region. The spectral function around $ω \sim 2 M_{q}$ is obtained using a non-perturbative complex potential, while for $ω ≫ 2 M_{q}$ it is modeled using results from vacuum perturbation theory. Since the pseudoscalar channel does not receive a transport contribution near $ω \sim 0$ , we find that the combination of these two regions already provides a good description of the relativistic lattice pseudoscalar correlator. We observe a substantial thermal width in the $η_{c} (1 S)$ state, indicating that pseudoscalar charmonium ( $η_{c}$ ) is nearing dissolution at the studied temperatures. In comparison, the $η_{b}$ ground state exhibits little change and remains well-defined.
↳ hep-lathep-exhep-phhep-th+1PRD(2025)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE

Distribution Functions of Λ and Σ0 Baryons

Some Aspects of Three-Quark Potentials (Part II)

Thermal Static Potential and Pseudo-Scalar Quarkonium Spectral Functions from 2+1 Flavor Lattice QCD

Affiliations

Distribution Functions of $Λ$ and $Σ^{0}$ Baryons