Sensitivity of Two-Body Non-Leptonic Branching Fractions to Theoretical Mass Variations in Heavy-Light Mesons

TL;DR

This paper examines how theoretical mass variations affect two-body non-leptonic decay rates of heavy-light mesons using factorization, highlighting the importance of accurate mass models for reliable predictions.

Contribution

It demonstrates the impact of different wavefunction-based mass models on decay predictions and suggests a simple, extendable formalism for unobserved exotic mesons.

Findings

Gaussian mass models yield more accurate decay rates in bottom mesons.

Mass variations cause non-linear sensitivity in branching fractions.

Hydrogenic masses better predict certain charm decay channels.

Abstract

This study investigates the sensitivity of two-body non-leptonic branching fractions to theoretical mass variations in heavy-light mesons ($D$, $D_s$, $B$, and $B_s$). Utilizing the factorization framework, we compare predictions derived from phenomenological masses evaluated with Gaussian and hydrogenic wavefunctions. For bottom meson decays, naive factorization with the number of color $N = 3$ aligns well with experimental data, and the $N \to \infty$ limit offers no improvement. Furthermore, the theoretical mass variation between wavefunction models induces a pronounced, non-linear sensitivity in the branching fractions, establishing the accurate Gaussian mass as a crucial baseline. Conversely, in the charm sector, naive factorization is inherently limited by final-state interactions due to insufficient relativistic recoil. While the $N \to \infty$ limit partially compensates for this, the systematically lower hydrogenic mass yields more accurate rates for several color-suppressed channels. This mass underestimation acts as a necessary kinematic regulator, cleanly offsetting the inflated amplitudes inherent to charm factorization. Ultimately, combining reliable Gaussian mass predictions with factorization provides a simple formalism extendable to the decay properties of unobserved exotics, such as excited $B_c$ mesons and $T_{bb}$ tetraquarks.