Pulsar braking indices offer insight into the physics that underlies pulsar spin-down .
Only five braking indices have been measured via phase-coherent timing ; all measured values are less than 3 , the value expected from magnetic dipole radiation .
Here we present new measurements for three of the five pulsar braking indices , obtained with phase-coherent timing for PSRs J1846 - 0258 ( n = 2.65 \pm 0.01 ) , B1509 - 58 ( n = 2.839 \pm 0.001 ) and B0540 - 69 ( n = 2.140 \pm 0.009 ) .
We discuss the implications of these results and possible physical explanations for them . \PACS 95.85.Nv 97.60.Gb