arXiv subjects

Joseph Torsiello

Publications and source records attributed to Joseph Torsiello.

3 recordsLinked to original sources

arXiv2026

Mellin Moments of Pion and Kaon Unpolarized PDFs from Nonlocal Operators in Lattice QCD

We present a first-principles lattice-QCD determination of Mellin moments of the unpolarized pion and kaon parton distribution functions using matrix elements of boosted mesons coupled to nonlocal operators containing a straight Wilson line. The calculation is performed on an $N_f=2+1+1$ ensemble of maximally twisted-mass fermions with a clover term, with lattice volume $32^3\times64$, lattice spacing $a=0.0934$ fm, and pion mass $m_π=260$ MeV. Matrix elements are computed for hadron momenta $P_3=0$, 0.41, 0.83, 1.25, 1.66, and 2.07 GeV and analyzed within the short-distance factorization framework. We investigate the dependence of the extracted moments on the truncation of the operator-product expansion, the coordinate-space fit window, and the perturbative accuracy of the Wilson coefficients, comparing next-to-leading-order and next-to-next-to-leading-order results. We also perform an RG-improved analysis as a consistency check of the perturbative treatment. Our final results are obtained from combined fits in $(P_3,z)$ space at next-to-next-to-leading-order and are quoted at $μ=2$ GeV. We also study the SU(3) symmetry-breaking effect and reconstruct the valence PDFs from the moments.

hep-lat↗

arXiv2026

Pion and Kaon PDFs from Lattice QCD via Large Momentum Effective Theory and Short-Distance Factorization

In this work, we present a first-principles lattice-QCD calculation of the unpolarized quark PDF for the pion and the kaon. The lattice data rely on matrix elements calculated for boosted mesons coupled to non-local operators containing a Wilson line. The calculations on this lattice ensemble correspond to two degenerate light, a strange, and a charm quark ($N_f=2+1+1$), using maximally twisted mass fermions with a clover term. The lattice volume is $32^3\times 64$, with a lattice spacing of 0.0934 fm, and a pion mass of 260 MeV. Matrix elements are calculated for hadron boosts of $|P_3| = 0,~0.41,~0.83,~1.25,~1.66,$ and 2.07 GeV. To match lattice QCD results to their light-cone counterparts, we employ two complementary frameworks: the large-momentum effective theory (LaMET) and the short-distance factorization (SDF). Using these approaches in parallel, we also test the lattice data to identify methodology-driven systematics. Results are presented for the standard quark PDFs, as well as the valence sector. Beyond obtaining the PDFs, we also explore the possibility of extracting information on SU(3) flavor-symmetry-breaking effects. For LaMET, we also parametrize the momentum dependence to obtain the infinite-momentum PDFs.

hep-lat↗

arXiv2022

Engineering frictional characteristics of MoS2 structure by tuning thickness and morphology- An atomic, electronic structure, and exciton analysis

We performed atomic and electron dynamics analysis to study the impact of morphological and thickness changes of a MoS2 system on its tribological properties through a diamond tip. We had considered 4 cases: variable layers (1-4 layers) and number (2-8 indents), radius (12Å, 16Å, 20Å, 24Å), and pattern of indents (0°, 25°, 30°, 35°, 45°, 60°) resulting into 18 subcases. MD results showed changing the radius and number of indents were the most, and number of layers and indents' pattern were the least effective way to tune the frictional characteristics. Ground state ab-initio study demonstrated an increase in the number and radius of indents, raising the number of stretched bonds. Consequently, the volume covered by the HOMO iso-surface increases, and that of LUMO decreases. That makes higher area/volume available to lose/share electrons, resulting in stronger interlocking between layers and tip. And TD-DFT calculation proves the existence of interfacial excitons, resulting in stronger interlocking between the layer's surface and tip despite a contraction in the LUMO iso-surfaces' area/volume. We believe these interlayer excitons result in higher average Z-axis(hence frictional force) reaction forces for the indents number subcases and lower for indents radius subcases as the number and radius of indents increase.

cond-mat.mtrl-sci↗