Explanipedia

Multi-nucleon matrix elements on the lattice with the Feynman-Hellmann theorem Open

Nabil Humphrey, Kadir Utku Can, R. Horsley, P. E. L. Rakow, G. Schierholz , et al. · 2025

Lattice QCD calculation of the Compton amplitude subtraction function Open

Kadir Utku Can, A. Hannaford-Gunn, R. Horsley, P. E. L. Rakow, T. Schar , et al. · 2025

The Compton amplitude subtraction function is an essential component in work concerning both the proton radius puzzle and the proton-neutron mass difference. However, owing to the difficulty in determining the subtraction function, it rema…

Gross-Llewellyn Smith sum rule from lattice QCD Open

NULL AUTHOR_ID, J. A. Crawford, R. Horsley, P. E. L. Rakow, T. Schar , et al. · 2025

We compute the Gross-Llewellyn Smith sum rule, i.e., the lowest odd moment of the parity-violating structure function, F3, of the nucleon from a lattice QCD calculation of the Compton amplitude. Our calculations are performed on 483×96 lat…

Multi-nucleon matrix elements on the lattice with the Feynman-Hellmann theorem Open

Nabil Humphrey, K. U. Can, R. Horsley, P. E. L. Rakow, G. Schierholz , et al. · 2025

This work presents the first calculation of the lowest moment of the forward Compton structure function $\mathcal{F}_2$ for a multi-nucleon deuteron-like state using Feynman-Hellmann lattice QCD techniques. Using this result as a prototypi…

Transverse Force Distributions in the Proton from Lattice QCD Open

J. A. Crawford, Kadir Utku Can, R. Horsley, P. E. L. Rakow, G. Schierholz , et al. · 2025

Single-spin asymmetries observed in polarized deep-inelastic scattering are important probes of hadron structure. The Sivers asymmetry has been the focus of much attention in QCD phenomenology and is yet to be understood at the quark level…

Fourier-accelerated HMC for the 2D SU(N) x SU(N) principal chiral model Open

B.J. Pendleton, R. Horsley, Pablo Morande · 2025

We report the results of Fourier-accelerated HMC simulations of 2D SU(N) X SU(N) principal chiral models for N = 2, 3, 4, 6, 9. These models share several key properties with 4D QCD, such as asymptotic freedom and dynamical mass generation…

Renormalisation Group Equations for 2+1 clover fermions Open

K. U. Can, R. Horsley, P. E. L. Rakow, G. Schierholz, H. Stüben , et al. · 2025

Many lattice QCD simulations now have many lattice spacings available, and it is of interest to investigate how they scale. In this talk we first derive renormalisation group equations appropriate for 2+1 clover fermions. This is then used…

The parity-odd structure function of nucleon from the Compton amplitude Open

K. Utku Can, R. Horsley, Yoshifumi Nakamura, P. E. L. Rakow, G. Schierholz , et al. · 2024

The dominant contribution to the theoretical uncertainty in the extracted weak parameters of the Standard Model comes from the hadronic uncertainties in the electroweak boxes, i.e. $\\gamma-W^\\pm/Z$ exchange diagrams. A dispersive analysi…

The parity-odd structure function of nucleon from the Compton amplitude Open

K. U. Can, R. Horsley, Y. Nakamura, P. E. L. Rakow, G. Schierholz , et al. · 2024

The dominant contribution to the theoretical uncertainty in the extracted weak parameters of the Standard Model comes from the hadronic uncertainties in the electroweak boxes, i.e. $\gamma-W^\pm/Z$ exchange diagrams. A dispersive analysis …

Hybrid Monte Carlo simulation with Fourier acceleration of the N = 2 principal chiral model in two dimensions Open

R. Horsley, B.J. Pendleton, J. F. Wack · 2023

Motivated by the similarity to QCD, specifically the property of asymptotic freedom, we simulate the dynamics of the SU(2) × SU(2) model in two dimensions using the Hybrid Monte Carlo algorithm. By introducing Fourier Acceleration, we show…

Constraining beyond the standard model nucleon isovector charges Open

R. E. Smail, M. Batelaan, R. Horsley, Yoshifumi Nakamura, H. Perlt , et al. · 2023

At the TeV scale, low-energy precision observations of neutron characteristics provide unique probes of novel physics. Precision studies of neutron decay observables are susceptible to beyond the Standard Model (BSM) tensor and scalar inte…

Hybrid Monte Carlo Simulation with Fourier Acceleration of the $N=2$ Principal Chiral Model in two Dimensions Open

R. Horsley, B.J. Pendleton, J. F. Wack · 2023

Motivated by the similarity to QCD, specifically the property of asymptotic freedom, we simulate the dynamics of the SU(2) $\times$ SU(2) model in two dimensions using the Hybrid Monte Carlo algorithm. By introducing Fourier Acceleration, …

Feynman-Hellmann approach to transition matrix elements and quasidegenerate energy states Open

M. Batelaan, Kadir Utku Can, R. Horsley, Yoshifumi Nakamura, P. E. L. Rakow , et al. · 2023

The Feynman-Hellmann approach to computing matrix elements in lattice QCD by first adding a perturbing operator to the action is described using the transition matrix and the Dyson expansion formalism. This perturbs the energies in the two…

The Compton amplitude and nucleon structure functions in lattice QCD Open

Kadir Utku Can, M. Batelaan, A. Hannaford-Gunn, R. Horsley, Y. Nakamura , et al. · 2023

The structure of hadrons relevant for deep-inelastic scattering are completely characterised by the Compton amplitude. A direct calculation of the Compton amplitude in a lattice QCD setup provides a way to accessing the structure functions…

Feynman--Hellmann approach to transition matrix elements and quasi-degenerate energy states Open

M. Batelaan, Kadir Utku Can, R. Horsley, Yoshifumi Nakamura, P. E. L. Rakow , et al. · 2023

The Feynman--Hellmann approach to computing matrix elements in lattice QCD by first adding a perturbing operator to the action is described using the transition matrix and the Dyson expansion formalism. This perturbs the energies in the tw…

Moments and power corrections of longitudinal and transverse proton structure functions from lattice QCD Open

M. Batelaan, Kadir Utku Can, A. Hannaford-Gunn, R. Horsley, Y. Nakamura , et al. · 2023

We present a simultaneous extraction of the moments of F2 and FL structure functions of the proton for a range of photon virtuality, Q2. This is achieved by computing the forward Compton amplitude on the lattice utilizing the second-order …

Quasi-degenerate baryon energy states, the Feynman-Hellmann theorem and transition matrix elements Open

R. Horsley, M. Batelaan, K.U. Can, Y. Nakamura, H Perlt , et al. · 2023

The standard method for determining matrix elements in lattice QCD requires the computation of three-point correlation functions. This has the disadvantage of requiring two large time separations: one between the hadron source and operator…

FLAG Review 2021 Open

Yasumichi Aoki, Tom Blum, Gilberto Colangelo, Sara Collins, Michele Della Morte , et al. · 2022

We review lattice results related to pion, kaon, D -meson, B -meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More specifically, we report on the determination of th…

Investigating the Compton amplitude subtraction function in lattice QCD Open

A. Hannaford-Gunn, Kadir Utku Can, R. Horsley, H. Perlt, P. E. L. Rakow , et al. · 2022

Theoretical predictions of the proton--neutron mass difference and measurements of the proton's charge radius require inputs from the Compton amplitude subtraction function. Model-dependent and non-relativistic calculations of this subtrac…

The Compton Amplitude, lattice QCD and the Feynman-Hellmann approach Open

Kadir Utku Can, A. Hannaford-Gunn, R. Horsley, Yasunobu Nakamura, H. Perlt , et al. · 2022

A major objective of lattice QCD is the computation of hadronic matrix elements. The standard method is to use three-point and four-point correlation functions. An alternative approach, requiring only the computation of two-point correlati…

Advances in lattice hadron physics calculations using the gradient flow Open

J. M. Zanotti, K. Utku Can, R. Horsley, Yoshifumi Nakamura, H. Perlt , et al. · 2022

Lattice calculations of hadronic observables are aggravated by short-distance fluctuations. The gradient flow, which can be viewed as a particular realisation of the coarse-graining step of momentum space RG transformations, proves a power…

Patterns of flavour symmetry breaking in hadron matrix elements involving u, d and s quarks Open

R. Horsley, J. M. Bickerton, A. N. Cooke, Y. Nakamura, H. Perlt , et al. · 2022

Using an SU(3)-flavour symmetry breaking expansion between the strange and light quark masses, we determine how this constrains the extrapolation of baryon octet matrix elements and form factors. In particular we can construct certain comb…

Nucleon Form Factors from the Feynman-Hellmann Method in Lattice QCD Open

M. Batelaan, R. Horsley, Yoshifumi Nakamura, H. Perlt, D. Pleiter , et al. · 2022

Lattice QCD calculations of the nucleon electromagnetic form factors are of interest at\nboth the high and low momentum transfer regions. For high momentum transfers especially there\nare open questions which require more intense study, su…

Measurements of $SU(3)_f$ symmetry breaking in B meson decay constants Open

S. E. Hollitt, S. A. De La Motte, R. Horsley, P. Jackson, Yoshifumi Nakamura , et al. · 2022

We present updates from UKQCD/QCDSF/CSSM on the $SU(3)_f$ breaking in $B$ meson decay constants. The $b$-quarks are generated with an anisotropic clover-improved action, and are tuned to match properties of the physical $B$ and $B^*$ meson…

Tensor Charges and their Impact on Physics Beyond the Standard Model Open

R. E. Smail, R. Horsley, Yoshifumi Nakamura, H. Perlt, D. Pleiter , et al. · 2022

The nucleon tensor charge, g$_T$, is an important quantity in the search for beyond the Standard Model tensor interactions in neutron and nuclear $\beta$-decays as well as the contribution of the quark electric dipole moment (EDM) to the n…

Generalised Parton Distributions from Lattice Feynman-Hellmann Techniques Open

A. Hannaford-Gunn, R. Horsley, H. Perlt, P. E. L. Rakow, G. Schierholz , et al. · 2022

We report on the use of Feynman-Hellmann techniques to calculate the off-forward Compton amplitude (OFCA) in lattice QCD. At leading-twist, the Euclidean OFCA is parameterised by the Mellin moments of generalised parton distributions (GPDs…

Investigating the low moments of the nucleon structure functions in lattice QCD Open

K. Utku Can, A. Hannaford-Gunn, Edward Sankey, R. Horsley, Yoshifumi Nakamura , et al. · 2022

We highlight QCDSF/UKQCD Collaboration's recent developments on computing the Compton amplitude directly via an implementation of the second order Feynman-Hellmann theorem. As an application, we compute the nucleon Compton tensor across a …

Report on scipost_202201_00026v1 Open

Kadir Utku Can, A. Hannaford-Gunn, R. Horsley, Y. Nakamura, H. Perlt , et al. · 2022

A major objective of lattice QCD is the computation of hadronic matrix elements.The standard method is to use three-point and four-point correlation functions.An alternative approach, requiring only the computation of two-point correlation…

Generalised Parton Distributions from Lattice Feynman-Hellmann Techniques Open

A. Hannaford-Gunn, Kadir Utku Can, R. Horsley, Holder Perlt, P. E. L. Rakow , et al. · 2022

We report on the use of Feynman-Hellmann techniques to calculate the off-forward Compton amplitude (OFCA) in lattice QCD. At leading-twist, the Euclidean OFCA is parameterised by the Mellin moments of generalised parton distributions (GPDs…

Generalized parton distributions from the off-forward Compton amplitude in lattice QCD Open

A. Hannaford-Gunn, Kadir Utku Can, R. Horsley, Y. Nakamura, H. Perlt , et al. · 2022

We determine the properties of generalized parton distributions (GPDs) from a lattice QCD calculation of the off-forward Compton amplitude (OFCA). By extending the Feynman-Hellmann relation to second-order matrix elements at off-forward ki…

R. Horsley YOU? Author Swipe