Alves, J. M., Botella, F. J., Branco, G. C., Cornet-Gomez, F., & Nebot, M. (2021). The framework for a common origin of delta(CKM) and delta S-PMN. Eur. Phys. J. C, 81(8), 727–11pp.
Abstract: We analyse a possible connection between CP violations in the quark and lepton sectors, parametrised by the CKM and PMNS phases. If one assumes that CP breaking arises from complexYukawa couplings, both in the quark and lepton sectors, the above connection is not possible in general, sinceYukawa couplings in the two sectors have independent flavour structures. We show that both the CKM and PMNS phases can instead be generated by a vacuum phase in a class of two Higgs doublet models, and in this case a connection may be established. This scenario requires the presence of scalar FCNC at tree level, both in the quark and lepton sectors. The appearance of these FCNC is an obstacle and a blessing. An obstacle since one has to analyse which models are able to conform to the strict experimental limits on FCNC, both in the quark and lepton sectors. A blessing, because this class of models is falsifiable since FCNC arise at a level which can be probed experimentally in the near future, specially in the processes h up arrow e(+/-) t +/- and t -> hc. The connection between CP violations in CKM and PMNS is explicitely illustrated in models with Minimal Flavour Violation.
|
Feijoo, A., Molina, R., Dai, L. R., & Oset, E. (2022). Lambda(1405) mediated triangle singularity in the K(-)d -> p Sigma(-) reaction. Eur. Phys. J. C, 82(11), 1028–16pp.
Abstract: We study for the first time the p Sigma(-) -> K- d and K- d -> p Sigma(-) reactions close to threshold and show that they are driven by a triangle mechanism, with the Lambda(1405), a proton and a neutron as intermediate states, which develops a triangle singularity close to the (K) over bard threshold. We find that a mechanism involving virtual pion exchange and the K- p -> pi(+)Sigma(-) amplitude dominates over another one involving kaon exchange and the K- p -> K- p amplitude. Moreover, of the two Lambda(1405) states, the one with higher mass around 1420 MeV, gives the largest contribution to the process. We show that the cross section, well within measurable range, is very sensitive to different models that, while reproducing (K) over barN observables above threshold, provide different extrapolations of the (K) over barN amplitudes below threshold. The observables of this reaction will provide new constraints on the theoretical models, leading to more reliable extrapolations of the (K) over barN amplitudes below threshold and to more accurate predictions of the Lambda(1405) state of lower mass.
|
ATLAS Collaboration(Aad, G. et al), Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Cardillo, F., Castillo, F. L., et al. (2022). Performance of the ATLAS Level-1 topological trigger in Run 2. Eur. Phys. J. C, 82(1), 7–26pp.
Abstract: During LHC Run 2 (2015-2018) the ATLAS Level-1 topological trigger allowed efficient data-taking by the ATLAS experiment at luminosities up to 2.1 x10(34) cm(-2) s(-1), which exceeds the design value by a factor of two. The system was installed in 2016 and operated in 2017 and 2018. It uses Field Programmable Gate Array processors to select interesting events by placing kinematic and angular requirements on electromagnetic clusters, jets, tau-leptons, muons and the missing transverse energy. It allowed to significantly improve the background event rejection and signal event acceptance, in particular for Higgs and B-physics processes.
|
Ling, P., Dai, X. H., Du, M. L., & Wang, Q. (2021). Prompt production of the hidden charm pentaquarks in the LHC. Eur. Phys. J. C, 81(9), 819–15pp.
Abstract: Motivated by the observation of the first hidden charm pentaquarks by the LHCb collaboration in 2015 and the updated analysis with an order-of-magnitude larger data set in 2019, we estimate their cross sections for the prompt production as well as their heavy quark spin partners, in the Sigma(()(c)*()) (D) over bar (()*()) hadronic molecular picture, at the center-of-mass energy 7 TeV in the pp collision. Their cross sections are several nb and we would expect several tens hidden charm pentaquark events in the LHC based on its current integrated luminosity. The cross sections show a sizable deviation of the cross sections for hidden charm pentaquarks with the third isospin component Iz = + 1/2 (P-c(+)) from those with Iz = – 1/2 (P-c(0)). The cross sections decrease dramatically with the increasing transverse momentum. Our study can also tell where to search for the missing hidden charm pentaquarks. The confirmation of the complete hidden charm pentaquarks in the heavy quark symmetry would further verify their Sigma(()(c)*()) (D) over bar (()*()) molecular interpretation. In addition, the relative strength among these cross sections for pentaquarks can help us to identify the quantum numbers of the P-c(4440) and P-c(4457).
|
Desai, N., Domingo, F., Kim, J. S., Ruiz de Austri, R., Rolbiecki, K., Sonawane, M., et al. (2021). Constraining electroweak and strongly charged long-lived particles with CheckMATE. Eur. Phys. J. C, 81(11), 968–19pp.
Abstract: Long-lived particles have become a new frontier in the exploration of physics beyond the Standard Model. In this paper, we present the implementation of four types of long-lived particle searches, viz. displaced leptons, disappearing track, displaced vertex with either muons or with missing transverse energy, and heavy charged tracks. These four categories cover the signatures of a large range of physics models. We illustrate their potential for exclusion and discuss their mutual overlaps in mass-lifetime space for two simple phenomenological models involving either a U(1)-charged or a coloured scalar.
|
