Speaker
Dr
Chia Cheng Chang
(Lawrence Berkeley National Laboratory)
Description
We calculate in three-flavor lattice QCD the short-distance hadronic matrix elements of all five $\Delta C=2$ four-fermion operators that contribute to neutral $D$-meson mixing both in and beyond the Standard Model. We use the MILC Collaboration's $N_f = 2+1$ lattice gauge-field configurations generated with asqtad-improved staggered sea quarks. We also employ the asqtad action for the valence light quarks and use the clover action with the Fermilab interpretation for the charm quark. We analyze a large set of ensembles with pions as light as $M_\pi \approx 180$ MeV and lattice spacings as fine as $a\approx0.045$ fm, thereby enabling good control over the extrapolation to the physical pion mass and continuum limit. We obtain for the matrix elements in the $\overline{\mathrm{MS}}-\mathrm{NDR}$ scheme using the choice of evanescent operators proposed by Beneke \emph{et al.}, evaluated at 3 GeV, $\langle D^0|\mathcal{O}_i|\bar{D}^0\rangle = \{0.0805(55)(16), -0.1561(70)(31), 0.0464(31)(9), 0.2747(129)(55), 0.1035(71)(21)\}~\text{GeV}^4$ ($i=1$ - 5). The errors shown are from statistics and lattice systematics, and the omission of charmed sea quarks, respectively. To illustrate the utility of our matrix-element results, we place bounds on the scale of CP-violating new physics in $D^0$ mixing, finding lower limits of about 10 - 50$\times 10^3$ TeV for couplings of $\mathrm{O}(1)$. To enable our results to be employed in more sophisticated or model-specific phenomenological studies, we provide the correlations among our matrix-element results. For convenience, we also present numerical results in the other commonly-used scheme of Buras, Misiak, and Urban.
Primary author
Dr
Chia Cheng Chang
(Lawrence Berkeley National Laboratory)
Co-authors
Prof.
Aida El-Khadra
(University of Illinois at Urbana-Champaign)
Prof.
Alexei Bazavov
(MSU)
Dr
Andreas Kronfeld
(FNAL)
Prof.
Carleton DeTar
(University of Utah)
Prof.
Chris Bouchard
(University of Glasgow)
Prof.
Claude Bernard
(Washington University in St. Louis)
Dr
Daping Du
(Syracuse University)
Prof.
Doug Toussaint
(University of Arizona)
Prof.
Elizabeth Freeland
(School of the Art Institute of Chicago)
Prof.
Elvira Gamiz
(Universidad de Granada)
Prof.
Ethan Neil
(University of Colorado, Boulder)
Prof.
Jack Laiho
(Syracuse University)
Dr
James Simone
(FNAL)
Dr
Paul Mackenzie
(FNAL)
Dr
Ran Zhou
(FNAL)
Prof.
Robert Sugar
(UCSB)
Dr
Ruth Van de Water
(FNAL)
Prof.
Steven Gottlieb
(Indiana University)
Prof.
Urs Heller
(APS)
