## Lattice QCD determination of neutron-antineutron matrix elements with physical quark masses [Lattice QCD determination of neutron-antineutron matrix elements at *m* _{π} = 135 MeV]

## Abstract

Matrix elements of six-quark operators are needed to extract new physics constraints from experimental searches for neutron-antineutron oscillations. This work presents, in detail, the first lattice quantum chromodynamics calculations of the necessary neutron-antineutron transition matrix elements including calculation methods and discussions of systematic uncertainties. Implications of isospin and chiral symmetry on the matrix elements, power counting in the isospin limit, and renormalization of a chiral basis of six-quark operators are discussed. Calculations are performed with a chiral-symmetric discretization of the quark action and physical light quark masses in order to avoid the need for chiral extrapolation. Nonperturbative renormalization is performed, including a study of lattice cutoff effects. Excited-state effects are studied using two nucleon operators and multiple values of source-sink separation. Results for the dominant matrix elements are found to be significantly larger compared to previous results from the MIT bag model. Future calculations are needed to fully account for systematic uncertainties associated with discretization and finite-volume effects but are not expected to significantly affect this conclusion.

- Authors:

- Brookhaven National Lab. (BNL), Upton, NY (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

- Publication Date:

- Research Org.:
- Brookhaven National Lab. (BNL), Upton, NY (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); RIKEN

- OSTI Identifier:
- 1508199

- Alternate Identifier(s):
- OSTI ID: 1511573

- Report Number(s):
- BNL-211592-2019-JAAM

Journal ID: ISSN 2470-0010; PRVDAQ

- Grant/Contract Number:
- SC0012704; FG02-00ER41132; SC0011090; AC52-07NA27344; AC02-06CH11357

- Resource Type:
- Published Article

- Journal Name:
- Physical Review D

- Additional Journal Information:
- Journal Volume: 99; Journal Issue: 7; Journal ID: ISSN 2470-0010

- Publisher:
- American Physical Society (APS)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 73 NUCLEAR PHYSICS AND RADIATION PHYSICS

### Citation Formats

```
Rinaldi, Enrico, Syritsyn, Sergey, Wagman, Michael L., Buchoff, Michael I., Schroeder, Chris, and Wasem, Joseph. Lattice QCD determination of neutron-antineutron matrix elements with physical quark masses [Lattice QCD determination of neutron-antineutron matrix elements at mπ = 135 MeV]. United States: N. p., 2019.
Web. doi:10.1103/PhysRevD.99.074510.
```

```
Rinaldi, Enrico, Syritsyn, Sergey, Wagman, Michael L., Buchoff, Michael I., Schroeder, Chris, & Wasem, Joseph. Lattice QCD determination of neutron-antineutron matrix elements with physical quark masses [Lattice QCD determination of neutron-antineutron matrix elements at mπ = 135 MeV]. United States. doi:10.1103/PhysRevD.99.074510.
```

```
Rinaldi, Enrico, Syritsyn, Sergey, Wagman, Michael L., Buchoff, Michael I., Schroeder, Chris, and Wasem, Joseph. Mon .
"Lattice QCD determination of neutron-antineutron matrix elements with physical quark masses [Lattice QCD determination of neutron-antineutron matrix elements at mπ = 135 MeV]". United States. doi:10.1103/PhysRevD.99.074510.
```

```
@article{osti_1508199,
```

title = {Lattice QCD determination of neutron-antineutron matrix elements with physical quark masses [Lattice QCD determination of neutron-antineutron matrix elements at mπ = 135 MeV]},

author = {Rinaldi, Enrico and Syritsyn, Sergey and Wagman, Michael L. and Buchoff, Michael I. and Schroeder, Chris and Wasem, Joseph},

abstractNote = {Matrix elements of six-quark operators are needed to extract new physics constraints from experimental searches for neutron-antineutron oscillations. This work presents, in detail, the first lattice quantum chromodynamics calculations of the necessary neutron-antineutron transition matrix elements including calculation methods and discussions of systematic uncertainties. Implications of isospin and chiral symmetry on the matrix elements, power counting in the isospin limit, and renormalization of a chiral basis of six-quark operators are discussed. Calculations are performed with a chiral-symmetric discretization of the quark action and physical light quark masses in order to avoid the need for chiral extrapolation. Nonperturbative renormalization is performed, including a study of lattice cutoff effects. Excited-state effects are studied using two nucleon operators and multiple values of source-sink separation. Results for the dominant matrix elements are found to be significantly larger compared to previous results from the MIT bag model. Future calculations are needed to fully account for systematic uncertainties associated with discretization and finite-volume effects but are not expected to significantly affect this conclusion.},

doi = {10.1103/PhysRevD.99.074510},

journal = {Physical Review D},

number = 7,

volume = 99,

place = {United States},

year = {2019},

month = {4}

}

DOI: 10.1103/PhysRevD.99.074510