arXiv subjects

Pei-Lin Yin

Publications and source records attributed to Pei-Lin Yin.

8 recordsLinked to original sources

arXiv2023

All-Orders Evolution of Parton Distributions: Principle, Practice, and Predictions

Parton distribution functions (DFs) are defining expressions of hadron structure. Exploiting the role of effective charges in quantum chromodynamics, an algebraic scheme is described which, given any hadron's valence parton DFs at the hadron scale, delivers predictions for all its DFs -- unpolarised and polarised -- at any higher scale. The scheme delivers results that are largely independent of both the value of the hadron scale and the pointwise form of the charge; and, inter alia, enables derivation of a model-independent identity that relates the strength of the proton's gluon helicity DF, $ΔG_p^ζ$, to that of the analogous singlet polarised quark DF and valence quark momentum fraction. Using available data fits and theory predictions, the identity yields $ΔG_p(ζ_{\rm C}=\surd 3{\rm GeV})=1.48(10)$. It furthermore entails that the measurable quark helicity contribution to the proton spin is $\tilde a_{0p}^{ζ_{\rm C}}=0.32(3)$, thereby reconciling contemporary experiment and theory.

hep-ph↗

arXiv2023

$Δ$-baryon axialvector and pseudoscalar form factors, and associated PCAC relations

A quark+diquark Faddeev equation treatment of the baryon bound state problem in Poincaré-invariant quantum field theory is used to deliver parameter-free predictions for all six $Δ$-baryon elastic weak form factors. Amongst the results, it is worth highlighting that there are two distinct classes of such $Δ$-baryon form factors, $(g_1, g_3, G_{πΔΔ})$, $(h_1, h_3, H_{πΔΔ})$, the functions within each of which are separately linked via partial conservation of axial current (PCAC) and Goldberger-Treiman (GT) relations. Respectively within each class, the listed form factors possess qualitatively the same structural features as the nucleon axial, induced pseudoscalar, and pion-nucleon coupling form factors. For instance, the $Δ$-baryon $g_1$ axial form factor can reliably be approximated by a dipole function, characterised by an axial charge $g_A^{Δ^+}=0.71(9)$ and mass-scale $m_A^Δ=0.95(2)m_Δ$. Moreover, the two distinct $Δ$-baryon PCAC form factor relations are satisfied to a high degree of accuracy on a large range of $Q^2$; the associated GT relations present good approximations only on $Q^2/m_Δ^2 \simeq 0$; and pion pole dominance approximations are reliable within both classes. There are two $πΔΔ$ couplings: $g_{πΔΔ} = 10.46(1.88)$; $h_{πΔΔ}= 35.73(3.75)$; and the associated form factors are soft. Such couplings commonly arise in phenomenology, which may therefore benefit from our analyses. A flavour decomposition of the axial charges reveals that quarks carry $71$\% of the $Δ$-baryon spin. The analogous result for the proton is $\approx 65$\%.

hep-ph↗

arXiv2023

Unpolarized generalized parton distributions of light and heavy vector mesons

We study the leading-twist unpolarized generalized parton distributions (GPDs) of light and heavy vector mesons, i.e., the $ρ$, $J/ψ$ and $Υ$, at zero skewness. An ansatz incorporating the zero mode contribution is introduced to modify the light front overlap representation of GPDs. The leading Fock-state light front wave functions (LF-LFWFs) of vector mesons from DS-BSEs approach are then employed to study the meson GPDs. The light front spatial distribution of valence quarks within vector mesons is then studied with the impact parameter dependent GPD (IPD GPD). We also investigate the electromagnetic and gravitational form factors, which are the first and second Mellin moments of the GPDs. The light-cone mass radius of $ρ$ is determined to be 0.30 fm, close to a recent NJL model prediction 0.32fm. For $J/ψ$ and $Υ$, they are predicted to be 0.151fm and 0.089 fm respectively.

hep-ph↗

arXiv2021

Masses of positive- and negative-parity hadron ground-states, including those with heavy quarks

A symmetry-preserving treatment of a vector$\times$vector contact interaction is used to compute spectra of ground-state $J^P = 0^\pm, 1^\pm$ $(f\bar g)$ mesons, their partner diquark correlations, and $J^P=1/2^\pm, 3/2^\pm$ $(fgh)$ baryons, where $f,g,h \in \{u,d,s,c,b\}$. Results for the leptonic decay constants of all mesons are also obtained, including scalar and pseudovector states involving heavy quarks. The spectrum of baryons produced by this chiefly algebraic approach reproduces the 64 masses known empirically or computed using lattice-regularised quantum chromodynamics with an accuracy of 1.4(1.2)%. It also has the richness of states typical of constituent-quark models and predicts many baryon states that have not yet been observed. The study indicates that dynamical, nonpointlike diquark correlations play an important role in all baryons; and, typically, the lightest allowed diquark is the most important component of a baryon's Faddeev amplitude.

hep-ph↗

arXiv2019

New algorithm to study the pseudo-Wigner solution of the quark gap equation in the framework of the (2+1)-flavor NJL model

In this paper, we study the pseudo-Wigner solution of the quark gap equation with a recently proposed algorithm in the framework of the (2+1)-flavor Nambu-Jona-Lasinio (NJL) model. We find that for the current quark mass $m_{\rm u,d}=5.5$ MeV and chemical potential $μ<μ_{\rm TCP}=272.5$ MeV, the Nambu solution and the positive pseudo-Wigner solution obtained via this algorithm is consistent with the physical solution obtained with the iterative method. Furthermore, the algorithm we used can help to illustrate the evolution of the solutions of the gap equation from the chiral limit to non-chiral limit and gives a prediction where the crossover line is located in the phase diagram for $μ<272.5$ MeV. In addition, we also study the chiral susceptibilities as well as the loss of solutions for different chemical potentials.

hep-ph↗

arXiv2019

Masses of ground-state mesons and baryons, including those with heavy quarks

Using a confining, symmetry-preserving regularisation of a vector$\times$vector contact interaction, we compute the spectra of ground-state pseudoscalar and vector $(f\bar g)$ mesons, scalar and axial-vector $(fg)$ diquarks, and $J^P=1/2^+, 3/2^+$ $(fgh)$ baryons, where $f,g,h \in \{u,d,s,c,b\}$. The diquark correlations are essentially dynamical and play a key role in formulating and solving the three-valence-quark baryon problems. The baryon spectrum obtained from this largely-algebraic approach reproduces the 22 known experimental masses with an accuracy of $2.9(2.4)$%. It also possesses the richness of states typical of constituent-quark models, predicting many heavy-quark baryons not yet observed. This study indicates that diquark correlations are an important component of all baryons; and owing to the dynamical character of the diquarks, it is typically the lightest allowed diquark correlation which defines the most important component of a baryon's Faddeev amplitude.

nucl-th↗

arXiv2017

Dynamical gap generation in 2D Dirac semimetal with deformed Dirac cone

According to the extensive theoretical and experimental investigations, it is widely accepted that the long-range Coulomb interaction is too weak to generate a dynamical excitonic gap in graphene with a perfect Dirac cone. We study the impact of the deformation of Dirac cone on dynamical gap generation. When a uniaxial strain is applied to graphene, the Dirac cone is made elliptical in the equal-energy plane and the fermion velocity becomes anisotropic. The applied uniaxial strain has two effects: it decreases the fermion velocity; it increases the velocity anisotropy. After solving the Dyson-Schwinger gap equation, we show that dynamical gap generation is promoted by the former effect, but is suppressed by the latter one. For suspended graphene, we find that the systems undergoes an excitonic insulating transition when the strain is roughly 7.34$\%$. We also solve the gap equation in case the Dirac cone is tiled, which might be realized in the organic material $α$-(BEDT-TTF)$_{2}$I$_{3}$, and find that the tilt of Dirac cone can suppress dynamical gap generation. It turns out that the geometry of the Dirac cone plays an important role in the formation of excitonic pairing.

cond-mat.str-el↗

arXiv2016

Effects of gauge boson mass on chiral and deconfinement phase transitions in QED$_{3}$

Based on the experimental observation that there is a coexisting region between the antiferromagnetic (AF) and $\textit{d}$-wave superconducting ($\textit{d}$SC) phases, the influences of gauge boson mass $m_{a}$ on chiral symmetry restoration and deconfinement phase transitions in QED$_{3}$ are investigated simultaneously within a unified framework, i.e., Dyson-Schwinger equations. The results show that the chiral symmetry restoration phase transition in the presence of the gauge boson mass $m_{a}$ is a typical second-order phase transition; the chiral symmetry restoration and deconfinement phase transitions are coincident; the critical number of fermion flavors $N^{c}_{f}$ decreases as the gauge boson mass $m_{a}$ increases and there exists a boundary that separates the $N^{c}_{f}$-$m_{a}$ plane into chiral symmetry breaking/confinement region for ($N_{f}^{c}$, $m_{a}$) below the boundary and chiral symmetry restoration/deconfinement region for ($N_{f}^{c}$, $m_{a}$) above it.

hep-ph↗