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 continue the program [1] of carving out the space of large $N$ confininggauge theories by modern S-matrix bootstrap methods, with the ultimate goal ofcornering large $N$ QCD. In this paper, we focus on the effective field theoryof massless pions coupled to background electromagnetic fields. We derive thefull set of positivity constraints encoded in the system of 2 $\to$ 2scattering amplitudes of pions and photons. This system probes a larger set ofintermediate meson states, and is thus sensitive to intricate large $N$selection rules, especially when supplemented with expectations from Reggetheory. It also has access to the coefficient of the chiral anomaly. We findnovel numerical bounds on several ratios of Wilson coefficients, in units ofthe rho mass. By matching the chiral anomaly with the microscopic theory, wealso derive bounds that contain an explicit $N$ dependence.

Bootstrapping Pions at Large $N$. Part II: Background Gauge Fields and the Chiral Anomaly