arXiv subjects

Yu-Lu Liu

Publications and source records attributed to Yu-Lu Liu.

3 recordsLinked to original sources

arXiv2026

Examining Temporal Characteristics of GCRs in the AMS-02 era

The energy spectra of Galactic cosmic rays (GCRs) serve as critical probes of their astrophysical origins and propagation mechanisms through the interstellar medium. Among the key physical processes shaping the observed spectra, solar modulation, driven by turbulent heliospheric magnetic fields and the variability of the solar wind, plays a dominant role in modifying GCR fluxes within the inner heliosphere. The recent release of time-dependent flux measurements for He, Li, Be, B, C, N, and O by AMS-02 provides unprecedented precision to investigate solar modulation phenomena. In this study, we demonstrate that Li, Be, B, C, N, and O nuclei exhibit solar modulation parameters consistent with those of protons (p) and He within a modified force-field approximation (FFA) framework incorporating rigidity-dependent modulation potentials. By positing that GCRs with the same charge-sign sharing the solar modulation parameters, we further forecast daily fluxes of Ne, Mg and Si from 2011 to 2020.

astro-ph.HE↗

arXiv2025

Evolution of unpolarized transverse momentum dependent parton distributions of twist-3

We revisit the calculation of the evolution equations for four unpolarized twist-3 transverse momentum dependent (TMD) parton distribution functions (PDFs) at $\mathcal {O}(α_s)$. Unlike the existing calculations in the literature, which are based on the background field method, we derive the evolution equations directly through diagram expansion. Additionally, instead of using the $δ$ regulator, we employ the exponential regulator to regularize the rapidity divergences. We find that the evolutions of the four twist-3 TMD PDFs are governed by eight homogeneous equations. Our evolution kernels agree with one set of results in the literature, but differ from another by a sign. Considering the advantages of the exponential regulator in high-order perturbative calculations, our results are crucial for computing the twist-3 TMD PDFs at $\mathcal {O}(α_s^2)$.

hep-ph↗

arXiv2011

Experimental Investigation of Longitudinal Space-Time Correlations of the Velocity Field in Turbulent Rayleigh-Bénard Convection

We report an experimental investigation of the longitudinal space-time cross-correlation function of the velocity field, $C(r,τ)$, in a cylindrical turbulent Rayleigh-Bénard convection cell using the particle image velocimetry (PIV) technique. We show that while the Taylor's frozen-flow hypothesis does not hold in turbulent thermal convection, the recent elliptic model advanced for turbulent shear flows [He & Zhang, \emph{Phys. Rev. E} \textbf{73}, 055303(R) (2006)] is valid for the present velocity field for all over the cell, i.e., the isocorrelation contours of the measured $C(r,τ)$ have a shape of elliptical curves and hence $C(r,τ)$ can be related to $C(r_E,0)$ via $r_E^2=(r-βτ)^2+γ^2τ^2$ with $β$ and $γ$ being two characteristic velocities. We further show that the fitted $β$ is proportional to the mean velocity of the flow, but the values of $γ$ are larger than the theoretical predictions. Specifically, we focus on two representative regions in the cell: the region near the cell sidewall and the cell's central region. It is found that $β$ and $γ$ are approximately the same near the sidewall, while $β\simeq0$ at cell center.

physics.flu-dyn↗