arXiv subjects

Malcolm Lazarow

Publications and source records attributed to Malcolm Lazarow.

6 recordsLinked to original sources

arXiv2026

Quark-mass dependence of two-nucleon scattering

Understanding how the properties of the visible Universe depend on the parameters of the Standard Model of particle physics requires \emph{ab initio} theoretical computations. To that end, we investigate the quark-mass dependence of low-energy nucleon-nucleon scattering in the deuteron and dineutron channels. We perform lattice-QCD calculations at pion masses $M_π\approx 200$ and $280$ MeV and compare their results to phenomenology at the physical point and to a previous calculation at $M_π\approx 710$ MeV. Scattering amplitudes, phase shifts, and threshold parameters are determined from finite-volume spectra using quantization conditions that explicitly incorporate long-distance effects from one-pion exchange. We analyze the pion-mass dependence of scattering lengths and effective ranges using chiral effective field theory with Weinberg and Kaplan-Savage-Wise power countings. From this, we estimate the pion-mass derivatives of the inverse scattering lengths and binding momentum, at the physical point. Both power countings indicate that the deuteron unbinds near $M_π\approx 220$ MeV.

hep-lat↗

arXiv2026

Two-nucleon scattering amplitudes at light quark masses from lattice QCD

We present a lattice-QCD determination of nucleon-nucleon scattering amplitudes at pion masses of $M_π\approx 200$ MeV and $M_π\approx 280$ MeV at a single lattice spacing $a \approx 0.064$ fm on two CLS ensembles. The finite-volume energy spectra are extracted from large Hermitian correlation matrices constructed within the distillation framework using an extensive basis of two-nucleon interpolating operators. To reliably relate the finite-volume spectra to the infinite-volume scattering amplitudes, we employ two recently developed formalisms that explicitly account for the long-range interaction generated by one-pion exchange: the plane-wave quantization condition and the relativistic left-hand-cut formalism. We discuss the quark-mass dependence of the nucleon-nucleon scattering lengths, effective ranges, shape parameters and pole positions. At all pion masses considered, our analysis prefers virtual states in both isospin channels by more than $1σ$. Comparing also results from our previous calculation at $M_π\approx 710$ MeV, we observe that the inverse scattering lengths and binding momenta approach their physical-point phenomenological values monotonically as the pion mass is varied.

hep-lat↗

arXiv2026

Preliminary study of the $H$ dibaryon in $N_{\rm f}=2+1$ lattice QCD

We present preliminary results on the $I=0$, $S=-2$ $H$ dibaryon in $N_{\rm f}=2+1$ QCD. The calculation is performed with heavier-than-physical quarks ($m_π\approx 280$ MeV) on a single CLS ensemble. Correlation matrices are constructed using the distillation technique and the three relevant channels, $ΛΛ$, $NΞ$, $ΣΣ$, are investigated to determine the interacting spectrum relevant for $S$-wave across multiple momentum frames. The scattering amplitude is determined by solving the corresponding two-body quantization condition. These preliminary results are part of the ongoing efforts to determine the properties of di-hyperons and to establish whether the $H$ dibaryon exists down to physical quark masses.

hep-lat↗

arXiv2024

A Gravitational Waveform Model for Detecting Accelerating Inspiraling Binaries

We present an analytic frequency-domain gravitational waveform model for an inspiraling binary whose center-of-mass undergoes a small acceleration, assumed to be constant during the detection, such as when it orbits a distant tertiary mass. The center-of-mass acceleration along the line of sight is incorporated as a new parameter that perturbs the standard TaylorF2 model. We calculate the wave phase to 3rd post-Newtonian order and first order in the acceleration. It is shown that acceleration most significantly modifies the wave phase in the low frequency portion of the signal, so ground-based detectors with a good sensitivity at low frequencies are the most effective at detecting this effect. We present a Fisher information calculation to quantify the detectability of this effect at advanced LIGO A Plus, Cosmic Explorer, and Einstein Telescope over the mass range of neutron stars and stellar-mass black holes, and discuss degeneracy between acceleration and other parameters. We also determine the parameter space where the acceleration is large enough that the wave phase model would have to be extended to nonlinear orders in the acceleration.

gr-qc↗

arXiv2022

The hyperon spectrum from lattice QCD

Hyperon decays present a promising alternative for extracting $\vert V_{us} \vert$ from lattice QCD combined with experimental measurements. Currently $\vert V_{us} \vert$ is determined from the kaon decay widths and a lattice calculation of the associated form factor. In this proceeding, I will present preliminary work on a lattice determination of the hyperon mass spectrum. I will additionally summarize future goals in which we will calculate the hyperon transition matrix elements, which will provide an alternative means for accessing $\vert V_{us} \vert$. This work is based on a particular formulation of SU(2) chiral perturbation theory for hyperons; determining the extent to which this effective field theory converges is instrumental in understanding the limits of its predictive power, especially since some hyperonic observables are difficult to calculate near the physical pion mass (e.g., hyperon-to-nucleon form factors), and thus the use of heavier than physical pion masses is likely to yield more precise results when combined with extrapolations to the physical point.}

hep-lat↗

arXiv2020

Nonlinear Polarization Transfer and Control of Two Laser Beams Overlapping in a Uniform Nonlinear Medium

A scheme for polarization control using two laser beams in a non-linear optical medium is studied using both co- and counter-propagating beam geometries. In particular, we show that under certain conditions it is possible for two laser beams to exchange their polarization states. A model accounting for a more realistic, 2D propagation geometry is presented. The 2D model produces drastically different results (compared to the 1D propagation geometry), creating difficulties for implementing polarization control in a realistic setting. A proposal for overcoming these difficulties by reducing the non-linear optical medium to a thin slab is presented.

physics.optics↗