Transverse-momentum-dependent wave functions with Glauber gluons in $B \to ππ$, $ρρ$ decays

We investigate the Glauber-gluon effect on the $B \to ππ$ and $ρρ$ decays, which is introduced via a convolution of a universal Glauber phase factor with transverse-momentum-dependent(TMD) meson wave functions in the $k_T$ factorization theorem. For an appropriate parametrization of the Glauber phase, it is observed that a TMD wave function for the pion ($ρ$ meson) with a weak (strong) falloff in parton transverse momentum $k_T$ leads to significant (moderate) modification of the $B^0 \to π^0 π^0$ ($B^0 \to ρ^0 ρ^0$) branching ratio: the former (latter) is enhanced (reduced) by about a factor of 2 (15\%). This observation is consistent with the dual role of the pion as a massless Nambu-Goldstone boson and as a $q \bar q$ bound state, which requires a tighter spatial distribution of its leading Fock state relative to higher Fock states. The agreement between the theoretical predictions and the data for all the $B \to ππ$ and $ρ^0 ρ^0$ branching ratios is then improved simultaneously, and it is possible to resolve the $B \to ππ$ puzzle.

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