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SUMMARY:Operator mixing with the gradient flow
DTSTART;VALUE=DATE-TIME:20220124T140000Z
DTEND;VALUE=DATE-TIME:20220124T150000Z
DTSTAMP;VALUE=DATE-TIME:20220127T153057Z
UID:indico-event-31644@indico.desy.de
DESCRIPTION:The hypothetical presence of a nonzero electric dipole moment
of the neutron would imply a violation of charge-parity symmetry (CP) whic
h is absent from the Standard Model. Toward the characterization of potent
ial BSM sources of CP violation\, we study effective interactions in which
the high-energy BSM fields are integrated out\, leaving a basis of higher
-dimensional\, local QCD operators. Since these are composite operators\,
any attempt at renormalization involves some sort of operator mixing\, whi
ch at hadronic scales must be studied nonperturbatively on the lattice. Na
turally\, the operator mixing is parametrized solely by the lattice spacin
g\, producing power and logarithmic divergences as the regulator is remove
d. We use the gradient flow to reparametrize the operator mixing in terms
of the flow time\, so that at fixed flow times\, each continuum limit may
be taken independently\, taking the physical $t\\rightarrow0^+$ limit only
at the end. Additionally\, since operators are multiplicatively renormali
zed at positive flow time\, it is trivial to identify the physical renorma
lized operators once the mixing matrix is computed. To that end\, the dive
rgent operator mixing may be calculated in perturbation theory to arbitrar
y order\, constraining the high-energy matching to nonperturbative results
. Moreover\, since the continuum limit is possible at each positive flow t
ime (identified with the inverse-squared renormalization scales)\, we may
renormalize our operator bases over a wide range of hadronic scales as wel
l. We study the renormalization of the quark chromoelectric dipole moment
(qCEDM)\, presenting both nonperturbative and next-to-leading-order pertur
bative results on the power-divergent mixing with the pseudoscalar density
with some perturbative results on the leading logarithms.\n\nhttps://indi
co.desy.de/event/31644/
LOCATION:Zoom
URL:https://indico.desy.de/event/31644/
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