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Figueroa, P., Garcia-Cely, C., & Landini, G. (2026). Dark neutrons as dark matter: collisions in halos and direct detection from dark CP violation. J. High Energy Phys., 10(10), 128–35pp.
Abstract: We consider confining gauge theories with a non-vanishing topological angle theta, which induces CP-violating interactions among dark pions and dark baryons, with dark matter consisting of dark neutrons. The theta term generates scalar pion-baryon couplings analogous to the CP-violating pion-nucleon interactions of QCD. These interactions give rise to an attractive long-range Yukawa potential mediated by the dark pions, whose strength is proportional to theta. Since the dark pions are naturally light pseudo-Goldstone bosons, the resulting force can lead to sizable dark matter self-interactions, providing a simple and theoretically motivated realization of the self-interacting dark matter paradigm.We also investigate the implications for direct detection in scenarios where the dark sector communicates with the Standard Model through a dark photon portal. The theta term induces dark electric dipole moments proportional to theta, which couple directly to the electric fields of nuclei and can substantially enhance direct detection rates. We show how the underlying interactions shape the recoil spectra and discuss the possibility of identifying the CP-violating origin of the signal through its time dependence. Finally, we analyze the interplay between dark matter self-interactions and direct detection signals, showing that both are controlled by the same CP-violating parameter. Our results demonstrate that the topological angle theta can play a central role in determining the phenomenology of composite dark matter.
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LHCb Collaboration(Aaij, R. et al), Fernandez Casani, A., Jaimes Elles, S. J., Libralon, S., Lucio Martinez, M., Martinez-Vidal, F., et al. (2026). Observation of the charmless purely baryonic decay Λb0 → Λp(p)over-bar. J. High Energy Phys., 08(8), 040–25pp.
Abstract: A search for the charmless purely baryonic decay Lambda(0)(b)-> Lambda p (p) over bar is performed using proton-proton collision data recorded by the LHCb experiment at a centre-of-mass energy of root s = 13TeV and corresponding to an integrated luminosity of 6.0 fb(-1). The signal decay is observed with a significance of 5.1 standard deviations. Its branching fraction is measured for the first time, relative to that of the topologically similar decay Lambda(0)(b)-> Lambda K+ K-. Contributions from intermediate charmonium resonances decaying to the p (p) over bar and K+ K- final states are explicitly excluded with a requirement on the invariant mass of the companion hadron system, m( h (h) over bar) < 2.85 GeV, where h stands for a proton or a charged kaon. The relative branching fraction is found to be B(Lambda(0)(b)-> Lambda p (p) over bar)/B(Lambda(0)(b)-> Lambda K+K-) = (5.1 +/- 1.3((stat)) +/- 0.3((syst))) x 10(-2).
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Peñalver, D., De Vito, M., Balbinot, R., & Fabbri, A. (2026). Sonic black holes with thick horizons in BECs. Phys. Rev. D, 114(6), 065030–21pp.
Abstract: We consider simple one dimensional models of acoustic black holes formed by Bose-Einstein condensates where the flow is stepwise homogeneous. We concentrate on the case in which an extended sonic region is present, i.e., a region where the flow velocity equals exactly the speed of sound. These models can be thought of as acoustic black holes with a thick horizon. Particular attention is devoted to the number of created particles and to the density-density correlation functions, these latter being at present time the experimental tool to identify Hawking-like radiation in acoustic black holes.
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Usui, A., Niezgoda, A., & Gessner, M. (2026). Spinor Bose-Einstein condensate as an analog simulator of molecular bending vibrations. Quantum, 10, 2226–19pp.
Abstract: We demonstrate that spinor Bose-Einstein condensates (BECs) can be operated as an analog simulator of the twodimensional vibron model. This algebraic model describes bending vibrations of molecules and, in the case of triatomic molecules, exhibits two phases where linear and bent configurations are stabilised. Spinor BECs can be engineered to simulate states that correspond to linear or bent triatomic molecules, with the Wigner function of the BEC encoding information about the molecular configuration. We show how quantum simulations of the bending dynamics of linear molecules can be realised, and how preparing a linear configuration in the bent phase leads to a dynamical instability. In the dynamics triggered by the corresponding instability, a significant amount of entanglement is generated, and we characterise the dynamics with the squeezing parameter and the quantum Fisher information (QFI). The scaling of the non-Gaussian sensitivity, described by the difference between squeezing and QFI, grows with the system size once the spinor system crosses from the linear to the bent phase, thus serving as a dynamical witness for the quantum phase transition.
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ATLAS Collaboration(Aad, G. et al), Ahuja, S., Aikot, A., Cabrera Urban, S., Cantero, J., Carrion Martinez, C., et al. (2026). Search for displaced decays of long-lived particles in events with missing transverse momentum in √s=13 TeV pp collisions with the ATLAS detector. J. High Energy Phys., 08(8), 016–62pp.
Abstract: A search for long-lived particles in events with significant missing transverse momentum and at least one displaced vertex is presented. This analysis is performed using 137 fb(-1) of pp collision data collected between 2016-2018 during Run 2 of the Large Hadron Collider by the ATLAS detector. Displaced vertices are identified using two different secondary vertexing algorithms, including a novel “fuzzy” vertexing algorithm optimized for identifying displaced decays of heavy quarks. Separate searches are performed using each algorithm, and the expected Standard Model background is independently estimated for each search using a data-driven procedure. No significant excess is observed over the background in either case. The results are used to set 95% confidence-level limits on potential beyond-the-Standard Model physics that could produce this final state. Results are interpreted in the context of four models: long-lived gluinos that form R-hadrons before decaying, neutralinos decaying via Higgs-mediated channels in the Bino-Wino coannihilation model, long-lived Higgsinos decaying to axinos, and an exotic Higgs portal model predicting displaced decays of light pseudoscalars.
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