相关论文: Roper Resonance and S_{11}(1535) from Lattice QCD

We present results for the first positive parity excited state of the nucleon, namely, the Roper resonance ($N^{{{1/2}}^{+}}$=1440 MeV) from a variational analysis technique. The analysis is performed for pion masses as low as 224 MeV in…

The low-lying even-parity states of the nucleon are explored in lattice QCD using the PACS-CS collaboration 2+1-flavor dynamical-QCD gauge-field configurations made available through the International Lattice Datagrid (ILDG). The…

We present a lattice QCD study of the puzzling positive-parity nucleon channel, where the Roper resonance $N^*(1440)$ resides in experiment. The study is based on an ensemble of gauge configurations with $N_f=2+1$ Wilson-clover fermions…

We study excited states of the nucleon in quenched lattice QCD with the spectral analysis using the maximum entropy method. Our simulations are performed on three lattice sizes $16^3\times 32$, $24^3\times 32$ and $32^3\times 32$, at…

Two different descriptions of the existing pion-nucleon scattering data in the region of the Roper resonance are constructed. Both descriptions fit the experimental data very well. In one scenario the resonance is the result of strong…

This brief review focuses on the low-lying even- and odd-parity excitations of the nucleon obtained in recent lattice QCD calculations. Commencing with a survey of the 2014-15 literature we'll see that results for the first even-parity…

The origin of the low-lying nature of the $N$*(1440), or Roper resonance, has been the subject of significant interest for many years, including several investigations using lattice QCD. The majority of lattice studies have not observed a…

We study positive and negative parity nucleons on the lattice using the chirally improved lattice Dirac operator. Our analysis is based on a set of three operators chi_i with the nucleon quantum numbers but in different representations of…

We study the quenched chiral behavior of the pion with mass as low as $\approx 180$ MeV. The calculation is done on a quenched lattice of size $16^3\times 28$ and $a = 0.2$ fm with 80 configurations using overlap fermions and an improved…

The calculation of the masses of the lightest nucleon resonances using lattice QCD is surveyed. Recent results for the mass of the first radial excitation of the nucleon, the Roper resonance, are reviewed and the interpretation in terms of…

A study of the chiral behavior of pseudoscalar masses and decay constants is carried out in quenched lattice QCD with Wilson fermions. Using the modified quenched approximation (MQA) to cure the exceptional configuration problem, accurate…

We present an overview of the correlation-matrix methods developed recently by the CSSM Lattice Collaboration for the isolation of excited states of the nucleon. Of particular interest is the first positive-parity excited-state of the…

We investigate the one pion decay of the Roper resonance $N^*(1440)$$\to$$N$${\pi}$ in the Sakai-Sugimoto model of the holographic QCD. The nucleon and Roper resonance emerge as ground and first excited states of the collective radial…

Using a correlation matrix analysis consisting of a variety of smearings, the CSSM Lattice collaboration has successfully isolated states associated with the Roper resonance and other "exotic" excited states such as the $\Lambda(1405)$ on…

We explore the chiral aspects of extrapolation of observables calculated within lattice QCD, using the nucleon magnetic moments as an example. Our analysis shows that the biggest effects of chiral dynamics occur for quark masses…

This talk contains an analysis of quenched chiral perturbation theory and its consequences. The chiral behavior of a number of quantities such as the pion mass $m_\pi^2$, the Bernard-Golterman ratios $R$ and $\chi$, the masses of nucleons,…

Using lattice QCD on a $16^{3}\times 24$ lattice at $\beta=6.0$, we examine the elastic limit of charge overlap functions in the quenched approximation for the pion and rho meson; results are compared to previous direct current insertion…

We report on our on-going effort to calculate the properties of light nuclei directly from quarks and gluons based on lattice QCD. After briefly introducing our motivations and aims, we describe our strategy of fixing the strange quark mass…

We present the lattice QCD simulation with the 2+1+1 flavor full QCD ensembles using near-physical quark masses and different spatial sizes $L$, at $a\sim$ 0.055 fm. The results suggest that spontaneous chiral symmetry breaking is…

We determine several quantities in quenched lattice QCD with exact chiral symmetry. For 100 gauge configurations generated with Wilson gauge action at $ \beta = 6.0 $ on the $ 16^3 \times 32 $ lattice, we compute quenched quark propagators…