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Son T. Nguyen

Publications and source records attributed to Son T. Nguyen.

9 recordsLinked to original sources
arXiv2026

Lattice Regularization of Non-relativistic Interacting Fermions in One Dimension

Few-body systems in one spatial dimension provide an ideal setting for testing lattice methods, since exact results are available against which lattice systematics can be assessed. We study two-component non-relativistic fermions with attractive contact interactions on a lattice, where the even ($s$-wave) interaction acts between opposite spins and the odd ($p$-wave) interaction between like spins, using exact diagonalization. The couplings are fixed entirely from two-body data. We demonstrate that the two-body couplings alone determine the few-body physics. We compute the three- and four-body systems' ground states when $s$- and $p$-wave interactions coexist and find that both of them, expressed relative to the two-body threshold, depend only on a single dimensionless parameter.

cond-mat.quant-gas↗
arXiv2025

Electromagnetic form factors of ${}^6$Li, ${}^7$Li, and ${}^7$Be in cluster effective field theory

Effective field theory (EFT) provides a powerful model-independent theoretical framework for illuminating complicated interactions across a wide range of physics areas and subfields. In this work, we consider the low-energy deuteron-Helium-4, triton-Helium-4, and helion-Helium-4 systems at low energies in cluster EFT. In particular, we focus on the deuteron + Helium-4 cluster configuration of the Lithium-6 nucleus, the triton + Helium-4 cluster configuration of the Lithium-7 nucleus, and the Helium-3-Helium-4 configuration of the Beryllium-7 nucleus, respectively. We illustrate how to directly extract the asymptotic normalization coefficient and several observables using experimental measurement of the electromagnetic form factors of these nuclei.

nucl-th↗
arXiv2024

Worldline Monte Carlo method for few body nuclear physics

In this work we introduce a worldline based fermion Monte Carlo algorithm for studying few body quantum mechanics of self-interacting fermions in the Hamiltonian lattice formulation. Our motivation to construct the method comes from our interest in studying renormalization of chiral nuclear effective field theory with lattice regularization. In particular we wish to apply our method to compute the lattice spacing dependence of local lattice interactions as we take the continuum limit of the lattice theory. Our algorithm can compute matrix elements of the operator $\exp(-βH)$ where $H$ is the lattice Hamiltonian and $β$ is a free real parameter. These elements help us compute deep bound states that are well separated from scattering states even at values of $β$ which are not very large. Computing these bound state energies accurately can help us study renormalization of the lattice theory. In addition to developing the algorithm, in this work we also introduce a finite volume renormalization scheme for the lattice Hamiltonian of the leading pionless effective field theory and show how it would work in the one and two body sectors.

nucl-th↗
arXiv2022

Large-$N_c$ constraints for elastic dark matter-light nucleus scattering in pionless effective field theory

Recent proposals for the use of light nuclei as dark matter direct detection targets necessitate a strong theoretical understanding of the nuclear physics involved. We perform relevant calculations for dark matter-light nucleus scattering in a combined pionless effective field theory and large-$N_c$ expansion, where $N_c$ is the number of quark colors. We include a general set of one-nucleon currents that have been used in other effective theories, as well as novel two-nucleon contact currents. First, we obtain constraints for the relative sizes of the dark matter couplings to the one- and two-nucleon currents through the large-$N_c$ expansion. Then, we use these constraints to make predictions for the relative sizes of spin-dependent and spin-independent cross sections for dark matter scattering off of a nucleon, a deuteron, a triton, and helium-3.

nucl-th↗
arXiv2022

Improving Domain Generalization by Learning without Forgetting: Application in Retail Checkout

Designing an automatic checkout system for retail stores at the human level accuracy is challenging due to similar appearance products and their various poses. This paper addresses the problem by proposing a method with a two-stage pipeline. The first stage detects class-agnostic items, and the second one is dedicated to classify product categories. We also track the objects across video frames to avoid duplicated counting. One major challenge is the domain gap because the models are trained on synthetic data but tested on the real images. To reduce the error gap, we adopt domain generalization methods for the first-stage detector. In addition, model ensemble is used to enhance the robustness of the 2nd-stage classifier. The method is evaluated on the AI City challenge 2022 -- Track 4 and gets the F1 score $40\%$ on the test A set. Code is released at the link https://github.com/cybercore-co-ltd/aicity22-track4.

cs.CV↗
arXiv2021

Hierarchical Transformer Encoders for Vietnamese Spelling Correction

In this paper, we propose a Hierarchical Transformer model for Vietnamese spelling correction problem. The model consists of multiple Transformer encoders and utilizes both character-level and word-level to detect errors and make corrections. In addition, to facilitate future work in Vietnamese spelling correction tasks, we propose a realistic dataset collected from real-life texts for the problem. We compare our method with other methods and publicly available systems. The proposed method outperforms all of the contemporary methods in terms of recall, precision, and f1-score. A demo version is publicly available.

cs.CL↗
arXiv2020

Large-$N_c$ and renormalization group constraints on parity-violating low-energy coefficients for three-derivative operators in pionless effective field theory

We extend from operators with one derivative to operators with three derivatives the analysis of two-body hadronic parity violation in a combined pionless effective field theory (EFT$_{π\!/}$) and large-$N_c$ expansion, where $N_c$ is the number of colors in quantum chromodynamics (QCD). In elastic scattering, these operators contribute to $S$-$P$ and $P$-$D$ wave transitions, with five operators and their accompanying low energy coefficients (LECs) characterizing the $S$-$P$ transitions and six operators and LECs those in $P$-$D$ transitions. We show that the large-$N_c$ analysis separates them into leading order in $N_c$, next-to-leading order in $N_c$, etc. Relationships among EFT$_{π\!/}$ LECs emerge in the large-$N_c$ expansion. We also discuss the renormalization scale dependence of these LECs. Our analysis can complement lattice QCD calculations and help prioritize future parity-violating experiments.

hep-ph↗
arXiv2017

Characterization of the metal-insulator transport transition for the two-particle Anderson model

We extend to the two-particle Anderson model the characterization of the metal-insulator transport transition obtained in the one-particle setting by Germinet and Klein. We show that, for any fixed number of particles, the slow spreading of wave packets in time implies the initial estimate of a modified version of the Bootstrap Multiscale Analysis. In this new version, operators are restricted to boxes defined with respect to the pseudo-distance in which we have the slow spreading. At the bottom of the spectrum, within the regime of one-particle dynamical localization, we show that this modified multiscale analysis yields dynamical localization for the two-particle Anderson model, allowing us to obtain a characterization of the metal-insulator transport transition for the two-particle Anderson model at the bottom of the spectrum.

math-ph↗