Reliable extraction of the $dB(\mathrm{E}1)\mathrm{/}dE$ for ${}^{11}$Be from its breakup at 520 MeV/nucleon

We analyze the breakup of the one-neutron halo nucleus ${}^{11}$Be measured at 520 MeV/nucleon at GSI on Pb and C targets within an eikonal description of the reaction including a proper treatment of special relativity. The Coulomb term of the projectile-target interaction is corrected at first order, while its nuclear part is described at the optical limit approximation. Excellent agreement with the data is obtained using a description of ${}^{11}$Be, which fits the breakup data of RIKEN. This solves the apparent discrepancy between the $dB(\mathrm{E}1)\mathrm{/}dE$ estimations from GSI and RIKEN for this nucleus.