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Title: Is negative longitudinal magnetoresistance a chiral-anomaly signature
Plain: Many semimetals conduct better when a magnetic field points along the current, as the chiral anomaly predicts, but uneven current flow inside the sample (current jetting) can produce the same effect.
Precise: In Weyl and Dirac semimetals (Na3Bi, Cd3As2, the TaAs family, ZrTe5), the chiral anomaly predicts a longitudinal conductivity increase $\Delta \sigma_{zz} = C_a B^2$ for $E$ parallel to $B$, with $C_a$ proportional to $v^{3}\tau_v/\mu^{2}$ ($v$ Fermi velocity, $\tau_v$ intervalley scattering time, $\mu$ chemical potential from the node). Determine for each material whether the measured negative magnetoresistance follows this scaling once current jetting and inhomogeneity are excluded. An answer is a material-by-material verdict with $\tau_v$ measured independently.
Settled by: Multi-contact potential mapping that excludes current jetting, with $C_a$ measured versus $\mu$ across gated or doped samples and compared with independently measured $\tau_v$.
Kind: well-posed
Answer type: identification
References: (empty)
Literature status: contested
Status note: (empty)
Posed since: 2013