Excited hadrons on the lattice: Baryons

Abstract

We present results for masses of excited baryons from a quenched calculation with Chirally Improved quarks at pion masses down to 350 MeV. Our analysis of the correlators is based on the variational method. In order to provide a large basis set for spanning the physical states, we use interpolators with different Dirac structures and Jacobi smeared quark sources of different width. Our spectroscopy results for a wide range of ground state and excited baryons are discussed.Comment: 11 pages, 8 figure

Three-particle quantization condition in a finite volume: 1. The role of the three-particle force

“…6 We have also checked that the same result is obtained when divergent integrals are regularized with a momentum cutoff Λ but we refrain from showing explicit expressions here. In this case, divergences up to fifth order in the cutoff Λ appear.…”

“…As an example, we quote the calculation of the parameters of the Roper resonance [1][2][3][4][5][6][7][8][9][10], which decays -at a substantial rate -into a nucleon and two pions. The finite-volume effects in such few-body systems are expected to be rather pronounced.…”

“…This generates a non-trivial dependence of the couplings C 0 and C 2 on the renormalization scale µ which must cancel in physical observables. 6 The Schrödinger equation for the wave function in the S-wave is rewritten as…”

Three-particle quantization condition in a finite volume: 2. General formalism and the analysis of data

“…As a prominent example, we cite the numerous attempts to calculate the mass of the Roper resonance and solve the problem of the level ordering between this resonance and the N * (1535) [41][42][43][44][45][46][47][48][49][50]. It is a well known experimental fact that the Roper resonance decays with a significant probability (up to 40%) into the final state of a nucleon and two pions.…”

The 1405MeV Lambda Resonance in Full-QCD

“…There have been quite a few Lattice QCD studies of the Λ baryon, however most have used the quenched approximation, and none have identified an odd-parity state low enough in energy to be identified with the Λ(1405) [2][3][4][5][6]. Most recently, Takahasi and Oki identified two nearly degenerate states at around 1.6 GeV [6].…”