Abstract
We present a determination of nucleon-nucleon scattering phase shifts for ℓ≥0. The S, P, D and F phase shifts for both the spin-triplet and spin-singlet channels are computed with lattice Quantum ChromoDynamics. For ℓ>0, this is the first lattice QCD calculation using the Lüscher finite-volume formalism. This required the design and implementation of novel lattice methods involving displaced sources and momentum-space cubic sinks. To demonstrate the utility of our approach, the calculations were performed in the SU(3)-flavor limit where the light quark masses have been tuned to the physical strange quark mass, corresponding to mπ=mK≈800 MeV. In this work, we have assumed that only the lowest partial waves contribute to each channel, ignoring the unphysical partial wave mixing that arises within the finite-volume formalism. This assumption is only valid for sufficiently low energies; we present evidence that it holds for our study using two different channels. Two spatial volumes of V≈(3.5 fm)3 and V≈(4.6 fm)3 were used. The finite-volume spectrum is extracted from the exponential falloff of the correlation functions. Said spectrum is mapped onto the infinite volume phase shifts using the generalization of the Lüscher formalism for two-nucleon systems.
| Original language | English |
|---|---|
| Pages (from-to) | 285-292 |
| Number of pages | 8 |
| Journal | Physics Letters B |
| Volume | 765 |
| DOIs | |
| State | Published - Feb 10 2017 |
| Externally published | Yes |
Funding
We would like to thank Raúl Briceño for extensive consultations regarding the finite volume formalism, as well as Dean Lee for discussions regarding the comparison between finite-volume bound state energies and unitarity. We would like to acknowledge W. Detmold, R. Edwards, D. Richards and K. Orginos for use of the JLab/W&M configurations used in this work. These calculations were performed with software built upon the Chroma software suite [76] and the optimized lattice QCD GPU library QUDA [77,78]. We also utilized the highly efficient HDF5 I/O Library [79] with an interface to HDF5 in the USQCD Software Stack added with SciDAC 3 support [80]. We thank the Lawrence Livermore National Laboratory (LLNL) Multiprogrammatic and Institutional Computing program for the Grand Challenge allocation. Our calculations were performed on the LLNL BG/Q supercomputer, Aztec cluster and Surface GPU cluster and on Edison at NERSC, the National Energy Research Scientific Computing Center (a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231). We thank LLNL for funding from LDRD 13-ERD-023. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work was supported in part by the Office of Nuclear Physics in the US Department of Energy under grants KB0301052 (SciDAC), DE-SC00046548 (Berkeley), and DE-AC02-05CH11231. The work of AWL was supported in part by the U.S. Department of Energy under contract DE-AC05-06OR23177, under which Jefferson Science Associates, LLC, manages and operates the Jefferson Lab, and by the U.S. DOE Early Career Award under contract DE-SC0012180.
| Funders | Funder number |
|---|---|
| Aztec cluster and Surface GPU cluster | |
| U.S. Department of Energy | DE-AC02-05CH11231, DE-SC0012180, KB0301052, DE-AC05-06OR23177, DE-SC00046548 |
| Office of Science | |
| Nuclear Physics | |
| Lawrence Livermore National Laboratory | |
| Laboratory Directed Research and Development | 13-ERD-023, DE-AC52-07NA27344 |
| National Energy Research Scientific Computing Center |