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Aiola, S., Amhis, Y., Billoir, P., Jashal, B. K., Henry, L., Oyanguren, A., et al. (2021). Hybrid seeding: A standalone track reconstruction algorithm for scintillating fibre tracker at LHCb. Comput. Phys. Commun., 260, 107713–5pp.
Abstract: We describe the Hybrid seeding, a stand-alone pattern recognition algorithm aiming at finding charged particle trajectories for the LHCb upgrade. A significant improvement to the charged particle reconstruction efficiency is accomplished by exploiting the knowledge of the LHCb magnetic field and the position of energy deposits in the scintillating fibre tracker detector. Moreover, we achieve a low fake rate and a small contribution to the overall timing budget of the LHCb real-time data processing.
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Borsato, M. et al, Zurita, J., Henry, L., Jashal, B. K., & Oyanguren, A. (2022). Unleashing the full power of LHCb to probe stealth new physics. Rep. Prog. Phys., 85(2), 024201–45pp.
Abstract: In this paper, we describe the potential of the LHCb experiment to detect stealth physics. This refers to dynamics beyond the standard model that would elude searches that focus on energetic objects or precision measurements of known processes. Stealth signatures include long-lived particles and light resonances that are produced very rarely or together with overwhelming backgrounds. We will discuss why LHCb is equipped to discover this kind of physics at the Large Hadron Collider and provide examples of well-motivated theoretical models that can be probed with great detail at the experiment.
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Calefice, L., Hennequin, A., Henry, L., Jashal, B. K., Mendoza, D., Oyanguren, A., et al. (2022). Effect of the high-level trigger for detecting long-lived particles at LHCb. Front. Big Data, 5, 1008737–13pp.
Abstract: Long-lived particles (LLPs) show up in many extensions of the Standard Model, but they are challenging to search for with current detectors, due to their very displaced vertices. This study evaluated the ability of the trigger algorithms used in the Large Hadron Collider beauty (LHCb) experiment to detect long-lived particles and attempted to adapt them to enhance the sensitivity of this experiment to undiscovered long-lived particles. A model with a Higgs portal to a dark sector is tested, and the sensitivity reach is discussed. In the LHCb tracking system, the farthest tracking station from the collision point is the scintillating fiber tracker, the SciFi detector. One of the challenges in the track reconstruction is to deal with the large amount of and combinatorics of hits in the LHCb detector. A dedicated algorithm has been developed to cope with the large data output. When fully implemented, this algorithm would greatly increase the available statistics for any long-lived particle search in the forward region and would additionally improve the sensitivity of analyses dealing with Standard Model particles of large lifetime, such as KS0 or Lambda (0) hadrons.
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LHCb Collaboration(Aaij, R. et al), Fernandez Casani, A., Jaimes Elles, S. J., Jashal, B. K., Libralon, S., Lucio Martinez, M., et al. (2026). First evidence of violation in beauty baryon to charmonium decays. Sci. Bull., 71(3), 547–557.
Abstract: A study of the difference in the CP asymmetries between Lambda(0)(b) -> J/psi p pi(-) and Lambda(0)(b) -> J/psi pK(-)decays, Delta A(CP), is performed using proton-proton collision data collected by the LHCb experiment in the years 2015-2018, corresponding to an integrated luminosity of 6fb(-1). This quantity is measured to be Delta A(CP) = (4.03 +/- 1.18 +/- 0.23)%, where the first uncertainty is statistical and the second is systematic. When combined with the previous LHCb result, a value of Delta A(CP) = (4.31 +/- 1.06 +/- 0.28)% is obtained, corresponding to a significance of 3.9 sigma against the CP symmetry hypothesis. Studies of triple-product asymmetries, which provide an additional probe of CP violation, show no significant deviation from CP symmetry.
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LHCb Collaboration(Aaij, R. et al), Fernandez Casani, A., Jaimes Elles, S. J., Jashal, B. K., Libralon, S., Martinez-Vidal, F., et al. (2025). Study of Ds1(2460)+ → Ds+ π+π- in B → (D)over-bar(*)Ds+π+π- decays. Sci. Bull., 70(9), 1432–1444.
Abstract: An amplitude analysis of the D-s1(2460)(+) -> D-s(+)pi(+)pi(-) transition is performed simultaneously in B-0 -> D-Ds+pi(+)pi(-), B+ -> (D) over bar D-0(s)+pi(+)pi(-), and B-0 -> D*D--(s)+pi(+)pi(-) decays. The study is based on a data sample of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of root s = 7,8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb(-1). A clear double-peak structure is observed in the m(pi(+)pi(-)) spectrum of the D-s1(2460)(+) -> D-s(+)pi(+)pi(-) decay. The data can be described either with a model including f(0)(500), f(0)(980), and f(2)(1270) resonances, in which the contributions of f(0)(980) and f(2)(1270) are unexpectedly large, or with a model including f(0)(500), a doubly charged open-charm tetraquark state T-c (s) over bar(++) and its isospin partner T-c (s) over bar(0). If the former is considered implausible, the T-c (s) over bar states are observed with high significance, and the data are consistent with isospin symmetry. When imposing isospin constraints between the two T-c (s) over bar states, their mass and width are determined to be (2327 +/- 13 +/- 13) MeV and (96 +/- 16(-23)(+170)) MeV, respectively, where the first uncertainty is statistical and the second is systematic. The mass is slightly below the DK threshold, and a spin-parity of 0(+) is favoured with high significance. (c) 2025 The Authors. Published by Elsevier B.V. and Science China Press.
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