Gorkavenko, V., Jashal, B. K., Kholoimov, V., Kyselov, Y., Mendoza, D., Ovchynnikov, M., et al. (2024). LHCb potential to discover long-lived new physics particles with lifetimes above 100 ps. Eur. Phys. J. C, 84(6), 608–15pp.
Abstract: For years, it has been believed that the main LHC detectors can play only a limited role of a lifetime frontier experiment exploring the parameter space of long-lived particles (LLPs)-hypothetical particles with tiny couplings to the Standard Model. This paper demonstrates that the LHCb experiment may become a powerful lifetime frontier experiment if it uses the new Downstream algorithm reconstructing tracks that do not allow hits in the LHCb vertex tracker. In particular, for many LLP scenarios, LHCb may be as sensitive as the proposed experiments beyond the main LHC detectors for various LLP models, including heavy neutral leptons, dark scalars, dark photons, and axion-like particles.
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Gonzalez-Sprinberg, G. A., & Vidal, J. (2015). The top quark right coupling in the tbW-vertex. Eur. Phys. J. C, 75(12), 615–11pp.
Abstract: The most general parametrization of the tbW vertex includes a right coupling V-R that is zero at tree level in the standard model. This quantity may be measured at the Large Hadron Collider where the physics of the top decay is currently investigated. This coupling is present in new physics models at tree level and/or through radiative corrections, so its measurement can be sensitive to non-standard physics. In this paper we compute the leading electroweak and QCD contributions to the top V-R coupling in the standard model. This value is the starting point in order to separate the standard model effects and, then, search for new physics. We also propose observables that can be addressed at the LHC in order to measure this coupling. These observables are defined in such a way that they do not receive tree level contributions from the standard model and are directly proportional to the right coupling. Bounds on new physics models can be obtained through the measurements of these observables.
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Gonzalez Felipe, R., Ivanov, I. P., Nishi, C. C., Serodio, H., & Silva, J. P. (2014). Constraining multi-Higgs flavour models. Eur. Phys. J. C, 74(7), 2953–12pp.
Abstract: To study a flavour model with a non-minimal Higgs sector one must first define the symmetries of the fields; then identify what types of vacua exist and how they may break the symmetries; and finally determine whether the remnant symmetries are compatible with the experimental data. Here we address all these issues in the context of flavour models with any number of Higgs doublets. We stress the importance of analysing the Higgs vacuum expectation values that are pseudo-invariant under the generators of all subgroups. It is shown that the only way of obtaining a physical CKM mixing matrix and, simultaneously, non-degenerate and non-zero quark masses is requiring the vacuum expectation values of the Higgs fields to break completely the full flavour group, except possibly for some symmetry belonging to baryon number. The application of this technique to some illustrative examples, such as the flavour groups Delta (27), A(4) and S-3, is also presented.
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Gomez-Izquierdo, J. C., Gonzalez-Canales, F., & Mondragon, M. (2015). Q(6) as the flavor symmetry in a non-minimal SUSY SU(5) model. Eur. Phys. J. C, 75(5), 221–16pp.
Abstract: We present a non-minimal renormalizable SUSY SU(5) model, with extended Higgs sector and right-handed neutrinos, where the flavor sector exhibits a Q(6) flavor symmetry. We analyzed the simplest version of this model, in which R-parity is conserved and the right-handed neutrino masses in the flavor doublet are considered with and without degeneracy. We find the generic form of the mass matrices both in the quark and lepton sectors. We reproduce, according to current data, the mixing in the CKM matrix. In the leptonic sector, in the general case where the right-handed neutrino masses are not degenerate, we find that the values for the solar, atmospheric, and reactor mixing angles are in very good agreement with the experimental data, both for a normal and an inverted hierarchy. In the particular casewhere the right-handed neutrinos masses are degenerate, the model predicts a strong inverted hierarchy spectrum and a sum rule among the neutrino masses. In this case the atmospheric and solar angles are in very good agreement with experimental data, and the reactor one is different from zero, albeit too small (theta(lth)(13) similar to 3.38.). This value constitutes a lower bound for.13 in the general case. We also find the range of the values for the neutrino masses in each case.
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Gnendiger, C., Signer, A., Stockinger, D., Broggio, A., Cherchiglia, A. L., Driencourt-Mangin, F., et al. (2017). To d, or not to d: recent developments and comparisons of regularization schemes. Eur. Phys. J. C, 77(7), 471–39pp.
Abstract: We give an introduction to several regularization schemes that deal with ultraviolet and infrared singularities appearing in higher-order computations in quantum field theories. Comparing the computation of simple quantities in the various schemes, we point out similarities and differences between them.
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