TY - JOUR

T1 - Exploratory Lattice QCD Study of the Rare Kaon Decay K+→π+ν ν ¯

AU - Bai, Ziyuan

AU - Christ, Norman H.

AU - Feng, Xu

AU - Lawson, Andrew

AU - Portelli, Antonin

AU - Sachrajda, Christopher T.

PY - 2017/6/21

Y1 - 2017/6/21

N2 - We report a first, complete lattice QCD calculation of the long-distance
contribution to the K+→π+ν ν ¯
decay within the standard model. This is a second-order weak process
involving two four-Fermi operators that is highly sensitive to new
physics and being studied by the NA62 experiment at CERN. While much of
this decay comes from perturbative, short-distance physics, there is a
long-distance part, perhaps as large as the planned experimental error,
which involves nonperturbative phenomena. The calculation presented
here, with unphysical quark masses, demonstrates that this contribution
can be computed using lattice methods by overcoming three technical
difficulties: (i) a short-distance divergence that results when the two
weak operators approach each other, (ii) exponentially growing,
unphysical terms that appear in Euclidean, second-order perturbation
theory, and (iii) potentially large finite-volume effects. A follow-on
calculation with physical quark masses and controlled systematic errors
will be possible with the next generation of computers.

AB - We report a first, complete lattice QCD calculation of the long-distance
contribution to the K+→π+ν ν ¯
decay within the standard model. This is a second-order weak process
involving two four-Fermi operators that is highly sensitive to new
physics and being studied by the NA62 experiment at CERN. While much of
this decay comes from perturbative, short-distance physics, there is a
long-distance part, perhaps as large as the planned experimental error,
which involves nonperturbative phenomena. The calculation presented
here, with unphysical quark masses, demonstrates that this contribution
can be computed using lattice methods by overcoming three technical
difficulties: (i) a short-distance divergence that results when the two
weak operators approach each other, (ii) exponentially growing,
unphysical terms that appear in Euclidean, second-order perturbation
theory, and (iii) potentially large finite-volume effects. A follow-on
calculation with physical quark masses and controlled systematic errors
will be possible with the next generation of computers.

U2 - 10.1103/PhysRevLett.118.252001

DO - 10.1103/PhysRevLett.118.252001

M3 - Article

SN - 0031-9007

VL - 118

SP - 252001

JO - Physical Review Letters

JF - Physical Review Letters

IS - 25

ER -