TY  - JOUR
AU  - Silvi, Giorgio
AU  - Paul, Srijit
AU  - Alexandrou, Constantia
AU  - Krieg, Stefan
AU  - Leskovec, Luka
AU  - Meinel, Stefan
AU  - Negele, John
AU  - Petschlies, Marcus
AU  - Pochinsky, Andrew
AU  - Rendon, Gumaro
AU  - Syritsyn, Sergey
AU  - Todaro, Antonino
TI  - $P$-wave nucleon-pion scattering amplitude in the $\Delta(1232)$ channel from lattice QCD
JO  - Physical review / D
VL  - 103
IS  - 9
SN  - 2470-0010
CY  - Melville, NY
PB  - Inst.
M1  - FZJ-2021-02538
SP  - 094508
PY  - 2021
AB  - We determine the $\Delta(1232)$ resonance parameters using lattice QCD and the L{\"u}scher method.  The resonance occurs in elastic pion-nucleon scattering with $J^P=3/2^+$ in the isospin $I = 3/2$, $P$-wave channel.  Our calculation is performed with $N_f=2+1$ flavors of clover fermions on a lattice with $L\approx 2.8$ fm. The pion and nucleon masses  are $m_\pi =255.4(1.6)$ MeV and $m_N=1073(5)$ MeV, respectively, and the strong decay channel $\Delta \rightarrow \pi N$ is found to be above the threshold.  To thoroughly map out the energy-dependence of the nucleon-pion scattering amplitude, we compute the spectra in all relevant irreducible  representations of the lattice symmetry groups for total momenta up to $\vec{P}=\frac{2\pi}{L}(1,1,1)$, including irreps that mix $S$ and $P$ waves.  We perform global fits of the amplitude parameters to up to 21 energy levels, using a Breit-Wigner model for the $P$-wave phase shift and the effective-range expansion for the $S$-wave phase shift.   From the location of the pole in the $P$-wave scattering amplitude, we obtain the resonance mass $m_\Delta=1378(7)(9)$ MeV and the coupling $g_{\Delta\text{-}\pi N}=23.8(2.7)(0.9)$.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000655868700008
DO  - DOI:10.1103/PhysRevD.103.094508
UR  - https://juser.fz-juelich.de/record/893066
ER  -