arXiv subjects

Andrew Hanlon

Publications and source records attributed to Andrew Hanlon.

25 records · Page 2Linked to original sources

arXiv2019

$Kπ$ scattering and excited meson spectroscopy using the stochastic LapH method

Elastic $I=1/2$, $s$- and $p$-wave $Kπ$ scattering amplitudes are simultaneously calculated using a Lüscher style analysis on a single ensemble of dynamical Wilson-clover fermions at $m_π\sim 230$ MeV. Partial wave mixing due to the reduced rotational symmetries of the finite volume is included up to $\ell=2$. We also present finite-volume QCD spectra on two large anisotropic lattices ($32^3 \times 256$, $24^3 \times 128$) with $m_π\sim 230,\ 390$ MeV respectively. In each symmetry channel, a large basis of one- and two-hadron interpolating operators is employed with all-to-all quark propagation treated using the stochastic LapH method.

hep-lat↗

arXiv2018

The $H$ dibaryon from lattice QCD with SU(3) flavor symmetry

We show recent results from the Mainz group using $N_f = 2 + 1$ CLS ensembles generated at the $SU(3)$ symmetric point. Temporal correlation functions using two-baryon interpolating operators are calculated with the distillation method. In addition to the spin-0 operators relevant for studying the $H$ dibaryon, we added spin-1 operators to our basis, thereby extending our results to other flavor sectors. These preliminary results show a finite-volume energy below the $ΛΛ$ threshold. Further calculations are necessary to establish whether the $H$ dibaryon is bound at the physical point.

hep-lat↗

arXiv2018

Scattering phase shift determinations from a two-scalar field theory

A field theory involving two interacting scalar fields, previously studied by Rummukainen and Gottlieb, is revisited. Our study is not restricted to the limit of large quartic couplings, and a Symanzik-improved action is used so that continuum dispersion relations work well. The Metropolis method, combined with a local microcanonical updating algorithm, is employed in our Monte Carlo calculations. Isotropic lattices ranging from $16^3 \times 48$ to $53^3 \times 48$ are used, and scattering phase shifts are determined using a Lüscher analysis with multiple partial waves.

hep-lat↗

arXiv2018

Determination of $s$- and $p$-wave $I=1/2$ $Kπ$ scattering amplitudes in $N_{\mathrm{f}}=2+1$ lattice QCD

The elastic $I=1/2$, $s$- and $p$-wave kaon-pion scattering amplitudes are calculated using a single ensemble of anisotropic lattice QCD gauge field configurations with $N_{\mathrm{f}} = 2+1$ flavors of dynamical Wilson-clover fermions at $m_π = 230\mathrm{MeV}$. A large spatial extent of $L = 3.7\mathrm{fm}$ enables a good energy resolution while partial wave mixing due to the reduced symmetries of the finite volume is treated explicitly.The $p$-wave amplitude is well described by a Breit-Wigner shape with parameters $m_{K^{*}}/m_π = 3.808(18)$ and $g^{\mathrm{BW}}_{K^{*}Kπ} = 5.33(20)$ which are insensitive to the inclusion of $d$-wave mixing and variation of the $s$-wave parametrization. An effective range description of the near-threshold $s$-wave amplitude yields $m_πa_0 = -0.353(25)$.

hep-lat↗

arXiv2017

Scattering from finite-volume energies including higher partial waves and multiple decay channels

A new implementation of estimating the two-to-two $K$-matrix from finite-volume energies based on the Luescher formalism is described. The method includes higher partial waves and multiple decay channels, and the fitting procedure properly includes all covariances and statistical uncertainties. The method is also simpler than previously used procedures. Formulas and software for handling total spins up to $S=2$ and orbital angular momenta up to $L=6$ are presented.

hep-lat↗

arXiv2017

Estimating the two-particle $K$-matrix for multiple partial waves and decay channels from finite-volume energies

An implementation of estimating the two-to-two $K$-matrix from finite-volume energies based on the Lüscher formalism and involving a Hermitian matrix known as the "box matrix" is described. The method includes higher partial waves and multiple decay channels. Two fitting procedures for estimating the $K$-matrix parameters, which properly incorporate all statistical covariances, are discussed. Formulas and software for handling total spins up to $S=2$ and orbital angular momenta up to $L=6$ are obtained for total momenta in several directions. First tests involving $ρ$-meson decay to two pions include the $L=3$ and $L=5$ partial waves, and the contributions from these higher waves are found to be negligible in the elastic energy range.

hep-lat↗

arXiv2015

Excited-state energies and scattering phase shifts from lattice QCD with the stochastic LapH method

Recent results in computing excited-state energies and meson-meson scattering phase shifts in lattice QCD are presented. A stochastic method of treating the low-lying modes of quark propagation that exploits Laplacian Heaviside quark-field smearing makes such studies possible now on large 32^3 x 256 and 48^3 x 128 lattices at near physical pion masses. Levels are identified using a variety of probe interpolating operators, which include both single-hadron and a large number of two-hadron operators.

hep-lat↗