$\Delta \mathit T$ = 1 WEAK NEUTRAL CURRENT FORBIDDEN
Allowed by higher-order electroweak interactions.
 $\Gamma\mathrm {( {{\mathit t}} \rightarrow {{\mathit H}} {{\mathit c}})}$ $/$ $\Gamma\mathrm {(total)}$ $<4.3\times 10^{-4}$ CL=95.0%
 $\Gamma\mathrm {( {{\mathit t}} \rightarrow {{\mathit H}} {{\mathit u}})}$ $/$ $\Gamma\mathrm {(total)}$ $<1.9\times 10^{-4}$ CL=95.0%
 $\Gamma\mathrm {( {{\mathit t}} \rightarrow {{\mathit \ell}^{+}} {{\overline{\mathit q}}} {{\overline{\mathit q}}^{\,'}} ({{\mathit q}}={{\mathit d}},{{\mathit s}},{{\mathit b}}; {{\mathit q}^{\,'}}={{\mathit u}},{{\mathit c}}))}$ $/$ $\Gamma\mathrm {(total)}$ $<1.6\times 10^{-3}$ CL=95.0%
 $\Gamma\mathrm {( {{\mathit t}} \rightarrow {{\mathit Z}} {{\mathit q}} ({{\mathit q}}={{\mathit u}},{{\mathit c}}))}$ $/$ $\Gamma\mathrm {(total)}$ [1] $<1.2\times 10^{-4}$ CL=95.0%

 [1] This limit is for $\Gamma\mathrm {( {{\mathit t}} \rightarrow {{\mathit Z}} {{\mathit q}})}/\Gamma\mathrm {( {{\mathit t}} \rightarrow {{\mathit W}} {{\mathit b}})}$.