The I=2 ππ S-wave Scattering Phase Shift from Lattice QCD
- Albert Einstein Zentrum fur Fundamentale Physik, Sidlerstrasse (Switzerland); Univ. of New Hampshire, Durham (New Hampshire)
- Univ. of Barcelona (Spain)
- Jefferson Lab., Newport News, VA (United States); College of William and Mary, Williamsburg, VA (United States)
- Univ. of Washington, Seattle, WA (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Indiana Univ., Bloomington, IN (United States)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
The π+π+ s-wave scattering phase-shift is determined below the inelastic threshold using Lattice QCD. Calculations were performed at a pion mass of mπ ≈ 390 MeV with an anisotropic nf = 2+1 clover fermion discretization in four lattice volumes, with spatial extent L ≈ 2.0, 2.5, 3.0 and 3.9 fm, and with a lattice spacing of bs ≈ 0.123 fm in the spatial direction and bt bs/3.5 in the time direction. The phase-shift is determined from the energy-eigenvalues of π+π+ systems with both zero and non-zero total momentum in the lattice volume using Luscher's method. Our calculations are precise enough to allow for a determination of the threshold scattering parameters, the scattering length a, the effective range r, and the shape-parameter P, in this channel and to examine the prediction of two-flavor chiral perturbation theory: mπ2 a r = 3+O(mπ2/Λχ2). Chiral perturbation theory is used, with the Lattice QCD results as input, to predict the scattering phase-shift (and threshold parameters) at the physical pion mass. Our results are consistent with determinations from the Roy equations and with the existing experimental phase shift data.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Contributing Organization:
- NPLQCD Collaboration
- Grant/Contract Number:
- AC05-06OR23177; AC02-05CH11231; FC02- 07ER41457; AC52-07NA27344; FC02-06ER41443; FG02-07ER41527; FG02-04ER41302; FG03- 97ER4014; AC02- 06CH11357)
- OSTI ID:
- 1035545
- Alternate ID(s):
- OSTI ID: 1099191
- Report Number(s):
- JLAB-THY-11-1381; DOE/OR/23177-1643; arXiv:1107.5023; TRN: US1201148
- Journal Information:
- Physical Review. D, Particles, Fields, Gravitation and Cosmology, Vol. 85, Issue 3; ISSN 1550-7998
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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