Tripartite entanglements seen from a relativistically moving frame

In the rest frame of an observer, amoving system of three spin -1/2 massive particles described by a Gaussian momentum distributed wave packet, is considered. The spin part is assumed be maximally entangled as the Greenberger-Horne-Zeilinger (GHZ) or the W state. In a boosted frame the spin entanglements change as a result of the Wigner rotation produced by the Lorentz transformation. As a measure for these tripartite entanglements, the logarithmic negativity is calculated for the corresponding reduced density matrix viewed in the boosted frame. For a specific Lorentz boost, when the momentum part of the system is separable, the logarithmic negativity for both the spin states desend uniformly to nonzero asymptotic values depending on the width of the momentum distribution. However, when the momentum part is perfectly correlated, there exist boosts with determined speed that completely remove the GHZ spin entanglement. Also, there exist boosts leading to minimal destruction of the GHZ entanglement, provided that the width of the momentum distribution is large enough. Interestingly, the W spin entanglement in this case is Lorentz invariant.