CP asymmetry in $B^{+}\to K^+\pi^{0}$ and New Physics

TL;DR

This paper investigates the discrepancy in CP asymmetry measurements between different B meson decays, exploring whether Standard Model or new physics, such as a two Higgs doublet model, can explain the observations.

Contribution

The study demonstrates that the observed CP asymmetry difference can be explained within the Standard Model using sum rules and parameters, and proposes a two Higgs doublet model as a plausible new physics solution.

Findings

Standard Model can accommodate data with specific parameters.

Modified electroweak penguins and new physics phases are viable explanations.

Two Higgs doublet model can resolve multiple anomalies simultaneously.

Abstract

The CP asymmetry in $B^0\to K^+\pi^-$ is expected to be similar to that in $B^+\to K^+\pi^0$. The experimental data however show $\sim 5\sigma$ difference between the two, leading to the so called $\Delta {A}_{K\pi}$ puzzle. Employing sum rule(s) following from (approximate) flavour symmetry, we show that it is possible to accommodate the observed experimental values within the standard model (SM) for a narrow range of parameters. Sub-leading terms can bring the theoretical predictions in better agreement with the data. Resolution via modified electroweak penguin contributions is possible for a large CP violating phase generated by the new physics. However, the data on polarization in $B\to VV(T)$, $B_s$-$\bar{B}_s$ mixing (and large CP phase) and $B^+\to\tau^+\nu_{\tau}$ rate can not be simultaneously accommodated within SM or new physics with only enhanced electroweak penguins. A plausible resolution to these, and not spoiling the $B\to K\pi$ rates and asymmetries, could be a general two Higgs doublet model.