English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We develop a new method that allows us to deal with two-photon intermediatestates in a lattice QCD calculation. We apply this method to perform afirst-principles calculation of the $\pi^0 \rightarrow e^+ e^-$ decayamplitude. Both the real and imaginary parts of amplitude are calculated. Theimaginary part is compared with the prediction of optical theorem todemonstrate the effectiveness of this method. Our result for the real part ofdecay amplitude is $19.68(52)(1.10) \ \text{eV}$, where the first error isstatistical and the second is systematic.

Calculating the Two-photon Contribution to $\pi^0 \rightarrow e^+ e^-$ Decay Amplitude