LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). Limits on neutral Higgs boson production in the forward region in pp collisions at root s=7 TeV. J. High Energy Phys., 05(5), 132–13pp.
Abstract: Limits on the cross-section times branching fraction for neutral Higgs bosons, produced in p p collisions at root s = 7 TeV, and decaying to two tau leptons with pseudorapidities between 2.0 and 4.5, are presented. The result is based on a dataset, corresponding to an integrated luminosity of 1.0 fb(-1), collected with the LHCb detector. Candidates are identified by reconstructing final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. A model independent upper limit at the 95% confidence level is set on a neutral Higgs boson cross-section times branching fraction. It varies from 8.6 pb for a Higgs boson mass of 90 GeV to 0.7 pb for a Higgs boson mass of 250 GeV, and is compared to the Standard Model expectation. An upper limit on tan beta in the Minimal Supersymmetric Model is set in the m(h0)(max) scenario. It ranges from 34 for a CP-odd Higgs boson mass of 90 GeV to 70 for a pseudo-scalar Higgs boson mass of 140 GeV.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Search for a dimuon resonance in the Upsilon mass region. J. High Energy Phys., 09(9), 147–21pp.
Abstract: A search is performed for a spin-0 boson, phi, produced in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, using prompt phi -> mu(+)mu(-) decays and a data sample corresponding to an integrated luminosity of approximately 3.0 fb(-1) collected with the LHCb detector. No evidence is found for a signal in the mass range from 5.5 to 15 GeV. Upper limits are placed on the product of the production cross-section and the branching fraction into the dimuon final state. The limits are comparable to the best existing over most of the mass region considered and are the first to be set near the Upsilon resonances.
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Krause, C., Pich, A., Rosell, I., Santos, J., & Sanz-Cillero, J. J. (2019). Colorful imprints of heavy states in the electroweak effective theory. J. High Energy Phys., 05(5), 092–51pp.
Abstract: We analyze heavy states from generic ultraviolet completions of the Standard Model in a model-independent way and investigate their implications on the low-energy couplings of the electroweak effective theory. We build a general effective Lagrangian, implementing the electroweak symmetry breaking SU(2)(L) circle times SU(2)(R) SU(2)(L+R) with a non-linear Nambu-Goldstone realization, which couples the known particles to the heavy states. We generalize the formalism developed in previous works [1, 2] to include colored resonances, both of bosonic and fermionic type. We study bosonic heavy states with J(P) = 0(+/-) and J(P) = 1(+/-), in singlet or triplet SU(2)(L+R) representations and in singlet or octet representations of SU(3)(C) , and fermionic resonances with that are electroweak doublets and QCD triplets or singlets. Integrating out the heavy scales, we determine the complete pattern of low-energy couplings at the lowest non-trivial order. Some specific types of (strongly- and weakly-coupled) ultraviolet completions are discussed to illustrate the generality of our approach and to make contact with current experimental searches.
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Jung, M., Pich, A., & Tuzon, P. (2010). Charged-Higgs phenomenology in the aligned two-Higgs-doublet model. J. High Energy Phys., 11(11), 003–45pp.
Abstract: The alignment in flavour space of the Yukawa matrices of a general two-Higgs-doublet model results in the absence of tree-level flavour-changing neutral currents. In addition to the usual fermion masses and mixings, the aligned Yukawa structure only contains three complex parameters zeta(f), which are potential new sources of CP violation [1]. For particular values of these three parameters all known specific implementations of the model based on discrete Z(2) symmetries are recovered. One of the most distinctive features of the two-Higgs-doublet model is the presence of a charged scalar H-+/-. In this work, we discuss its main phenomenological consequences in flavour-changing processes at low energies and derive the corresponding constraints on the parameters of the aligned two-Higgs-doublet model.
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Jung, M., & Pich, A. (2014). Electric dipole moments in two-Higgs-doublet models. J. High Energy Phys., 04(4), 076–42pp.
Abstract: Electric dipole moments are extremely sensitive probes for additional sources of CP violation in new physics models. Specifically, they have been argued in the past to exclude new CP-violating phases in two-Higgs-doublet models. Since recently models including such phases have been discussed widely, we revisit the available constraints in the presence of mechanisms which are typically invoked to evade flavour-changing neutral currents. To that aim, we start by assessing the necessary calculations on the hadronic, nuclear and atomic/molecular level, deriving expressions with conservative error estimates. Their phenomenological analysis in the context of two-Higgs-doublet models yields strong constraints, in some cases weakened by a cancellation mechanism among contributions from neutral scalars. While the corresponding parameter combinations do not yet have to be unnaturally small, the constraints are likely to preclude large effects in other CP-violating observables. Nevertheless, the generically expected contributions to electric dipole moments in this class of models lie within the projected sensitivity of the next-generation experiments.
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