scholarly journals Interactions of two and three mesons including higher partial waves from lattice QCD

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Tyler D. Blanton ◽  
Andrew D. Hanlon ◽  
Ben Hörz ◽  
Colin Morningstar ◽  
Fernando Romero-López ◽  
...  
Keyword(s):  
Lattice Qcd ◽  
Effective Field Theory ◽  
Energy Levels ◽  
Particle Energy ◽  
Effective Field ◽  
Chiral Perturbation ◽  
Wave Interactions ◽  
Statistical Precision ◽  
K Matrix ◽  
First Time

Abstract We study two- and three-meson systems composed either of pions or kaons at maximal isospin using Monte Carlo simulations of lattice QCD. Utilizing the stochastic LapH method, we are able to determine hundreds of two- and three-particle energy levels, in nine different momentum frames, with high precision. We fit these levels using the relativistic finite-volume formalism based on a generic effective field theory in order to determine the parameters of the two- and three-particle K-matrices. We find that the statistical precision of our spectra is sufficient to probe not only the dominant s-wave interactions, but also those in d waves. In particular, we determine for the first time a term in the three-particle K-matrix that contains two-particle d waves. We use three Nf = 2 + 1 CLS ensembles with pion masses of 200, 280, and 340 MeV. This allows us to study the chiral dependence of the scattering observables, and compare to the expectations of chiral perturbation theory.

scholarly journals Test of the Skyrme effective field theory using quenched lattice QCD

1994 ◽  
Vol 570 (3-4) ◽  
pp. 521-542 ◽  
Author(s):  
M.-C. Chu ◽  
Marcello Lissia ◽  
J.W. Negele
Keyword(s):  
Field Theory ◽  
Lattice Qcd ◽  
Effective Field Theory ◽  
Effective Field

scholarly journals Parton Distribution Functions and Lattice QCD

2019 ◽  
Vol 206 ◽  
pp. 01003
Author(s):  
Huey-Wen Lin
Keyword(s):  
Lattice Qcd ◽  
Parton Distribution ◽  
Pion Mass ◽  
Effective Field ◽  
Distribution Functions ◽  
Large Momentum ◽  
Parton Distribution Functions ◽  
Proton Structure ◽  
Nonperturbative Renormalization ◽  
First Time

Recently, there have been rapid developments in lattice-QCD calculations of proton structure, especially in the parton distribution functions (PDFs). We overcame a longstanding obstacle and for the first time in lattice-QCD are able to directly calculate the Bjorken-x dependence of the quark, helicity and transversity distributions. The PDFs are obtained using the large-momentum effective field theory (LaMET) framework where the full Bjorken-x dependence of finite-momentum PDFs, called “quasi-PDFs”, can be calculated on the lattice. The quasi-PDF nucleon matrix elements are renormalized non-perturbatively in RI/MOM-scheme. Following a nonperturbative renormalization of the parton quasi-distribution in a regularization-independent momentum-subtraction scheme, we establish its matching to the $ \overline {{\rm{MS}}} $ PDF and calculate the non-singlet matching coefficient at next-to-leading order in perturbation theory. In this proceeding, I will show the progress that has been made in recent years, highlighting the latest state-of-the art PDF calculations at the physical pion mass. Future impacts on the large-x global PDF fits are also discussed.

scholarly journals Hamiltonian effective field theory study of the N*(1440) resonance in lattice QCD

2017 ◽  
Vol 95 (3) ◽  
Author(s):  
Zhan-Wei Liu ◽  
Waseem Kamleh ◽  
Derek B. Leinweber ◽  
Finn M. Stokes ◽  
Anthony W. Thomas ◽  
...  
Keyword(s):  
Field Theory ◽  
Lattice Qcd ◽  
Effective Field Theory ◽  
Effective Field

scholarly journals N3LO gravitational spin-orbit coupling at order G4

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Michèle Levi ◽  
Andrew J. McLeod ◽  
Matthew von Hippel
Keyword(s):  
Effective Field Theory ◽  
Dimensional Regularization ◽  
Effective Field ◽  
Compact Objects ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Transcendental Numbers ◽  
Integration Techniques ◽  
First Time

Abstract In this paper we derive for the first time the N3LO gravitational spin-orbit coupling at order G4 in the post-Newtonian (PN) approximation within the effective field theory (EFT) of gravitating spinning objects. This represents the first computation in a spinning sector involving three-loop integration. We provide a comprehensive account of the topologies in the worldline picture for the computation at order G4. Our computation makes use of the publicly-available EFTofPNG code, which is extended using loop-integration techniques from particle amplitudes. We provide the results for each of the Feynman diagrams in this sector. The three-loop graphs in the worldline picture give rise to new features in the spinning sector, including divergent terms and logarithms from dimensional regularization, as well as transcendental numbers, all of which survive in the final result of the topologies at this order. This result enters at the 4.5PN order for maximally-rotating compact objects, and together with previous work in this line, paves the way for the completion of this PN accuracy.

scholarly journals New positivity bounds from full crossing symmetry

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Andrew J. Tolley ◽  
Zi-Yue Wang ◽  
Shuang-Yong Zhou
Keyword(s):  
Field Theory ◽  
Dispersion Relation ◽  
Effective Field Theory ◽  
Scattering Amplitude ◽  
Effective Field ◽  
Field Theories ◽  
Upper And Lower Bounds ◽  
Chiral Perturbation ◽  
Partial Wave Expansion ◽  
Crossing Symmetry

Abstract Positivity bounds are powerful tools to constrain effective field theories. Utilizing the partial wave expansion in the dispersion relation and the full crossing symmetry of the scattering amplitude, we derive several sets of generically nonlinear positivity bounds for a generic scalar effective field theory: we refer to these as the P Q, Dsu, Dstu and $$ {\overline{D}}^{\mathrm{stu}} $$ D ¯ stu bounds. While the PQ bounds and Dsu bounds only make use of the s↔u dispersion relation, the Dstu and $$ {\overline{D}}^{\mathrm{stu}} $$ D ¯ stu bounds are obtained by further imposing the s↔t crossing symmetry. In contradistinction to the linear positivity for scalars, these inequalities can be applied to put upper and lower bounds on Wilson coefficients, and are much more constraining as shown in the lowest orders. In particular we are able to exclude theories with soft amplitude behaviour such as weakly broken Galileon theories from admitting a standard UV completion. We also apply these bounds to chiral perturbation theory and we find these bounds are stronger than the previous bounds in constraining its Wilson coefficients.

scholarly journals Chiral Perturbation Theory at NNNLO

Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1262
Author(s):  
Nils Hermansson-Truedsson
Keyword(s):  
Field Theory ◽  
Perturbation Theory ◽  
Effective Field Theory ◽  
Chiral Perturbation Theory ◽  
Pion Mass ◽  
Effective Field ◽  
Leading Order ◽  
Chiral Perturbation ◽  
Effective Lagrangian ◽  
Low Energies

Chiral perturbation theory is a much successful effective field theory of quantum chromodynamics at low energies. The effective Lagrangian is constructed systematically order by order in powers of the momentum p2, and until now the leading order (LO), next-to leading order (NLO), next-to-next-to leading order (NNLO) and next-to-next-to-next-to leading order (NNNLO) have been studied. In the following review we consider the construction of the Lagrangian and in particular focus on the NNNLO case. We in addition review and discuss the pion mass and decay constant at the same order, which are fundamental quantities to study for chiral perturbation theory. Due to the large number of terms in the Lagrangian and hence low energy constants arising at NNNLO, some remarks are made about the predictivity of this effective field theory.

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