The Bethe ansatz represents an analytical method enabling the exact solution of numerous models in condensed matter physics and statistical mechanics. When a global symmetry is present, the trial wavefunctions of the Bethe ansatz consist of plane wave superpositions. We show that the Bethe ansatz can be recast as a deterministic quantum circuit, and determine the analytical expression of the circuit gates. As a crucial step of the derivation, we present a simple set of diagrammatic rules that define a novel Matrix Product State network building Bethe wavefunctions. Remarkably, this provides a new perspective on the equivalence between the coordinate and algebraic versions of the Bethe ansatz. This approach allows to efficiently prepare the eigenstates of the XX model on a quantum computer with quantum resources that match previous state-of-the-art approaches. Using these ideas, we also obtain the first quantum circuit able to prepare efficiently all eigenstates of an interacting spin chain, the folded XXZ model. We run small-scale error-mitigated implementations on the IBM quantum computers, including the preparation of the ground state for the XX and XXZ models on 4 sites, and performed error-mitigated noisy simulations for small folded XXZ circuits assuming different qubit connectivities, achieving a relative error below 5%.

A dark photon is a massive dark-sector force mediator. This dark-sector could be weakly-interacting with the regular matter, whereas the dark photon, even if, in the minimal model, not coupling directly to the Standard Model particles, could kinetically mix to the regular photon via a suppression factor.

LHCb is a spectrometer in the forward region. It was originally designed as a heavy-flavor detector although it has been shown for long now its potential as a general purpose experiment. Specifically, LHCb has been able to show its sensitivity to dark sectors in pp collisions in a complementary way with respect to, for instance, ATLAS and CMS. LHCb has conducted a search for a massive dark photon decaying to two muons in the mass range [211 MeV, 70 GeV] using the full Run 2 data delivered by the LHC. Right now, LHCb is collecting the Run 3 data with the upgraded detector and trigger system. The removal of the hardware trigger and the incorporation of a triggerless readout and a GPU based software trigger in the first selection layer, allows to implement neural metwork based electron and muon identification algorithms. This not only optimizes the sensitivity to the dimuon final state but also enables a more challenging dielectron search, below the dimuon threshold. 

Director: Christoph Adam

In this talk I will present a systematic procedure to compute the effective action that governs the dynamics of Goldstone degrees of freedom associated to the breaking of spacetime symmetries in the formation of domain wall and string defects, as well as their couplings to other massive modes such as bound states. I will show how the predictions of such effective action compare to the true, field theoretical evolution for collapsing domain walls, and argue that no curvature corrections should appear in the case of collapsing strings, as opposed to previous claims in the literature.