Pich, A., & Rodriguez-Sanchez, A. (2016). Determination of the QCD coupling from ALEPH tau decay data. Phys. Rev. D, 94(3), 034027–26pp.
Abstract: We present a comprehensive study of the determination of the strong coupling from tau decay, using the most recent release of the experimental ALEPH data. We critically review all theoretical strategies used in previous works and put forward various novel approaches which allow one to study complementary aspects of the problem. We investigate the advantages and disadvantages of the different methods, trying to uncover their potential hidden weaknesses and test the stability of the obtained results under slight variations of the assumed inputs. We perform several determinations, using different methodologies, and find a very consistent set of results. All determinations are in excellent agreement, and allow us to extract a very reliable value for alpha(s)(m(tau)(2)). The main uncertainty originates in the pure perturbative error from unknown higher orders. Taking into account the systematic differences between the results obtained with the contour-improved perturbation theory and fixed-order perturbation theory prescriptions, we find alpha((nf=3))(s) (m(tau)(2)) = 0.328 +/- 0.013 which implies alpha((nf=5))(s) (M-Z(2)) = 0.1197 +/- 0.0015.
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Maiezza, A., Nemevsek, M., & Nesti, F. (2016). Perturbativity and mass scales in the minimal left-right symmetric model. Phys. Rev. D, 94(3), 035008–11pp.
Abstract: The scalar sector of the minimal left-right model at TeV scale is revisited in light of the large quartic coupling needed for a heavy flavor-changing scalar. The stability and perturbativity of the effective potential is discussed and merged with constraints from low-energy processes. Thus, the perturbative level of the left-right scale is sharpened. Lower limits on the triplet scalars are also derived: The left-handed triplet is bounded by oblique parameters, while the doubly charged right-handed component is limited by the h -> gamma gamma, Z gamma decays. Current constraints disfavor their detection as long as W-R is within the reach of the LHC.
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Hiller Blin, A. N., Fernandez-Ramirez, C., Jackura, A., Mathieu, V., Mokeev, V. I., Pilloni, A., et al. (2016). Studying the P-c(4450) resonance in J/psi photoproduction off protons. Phys. Rev. D, 94(3), 034002–8pp.
Abstract: A resonancelike structure, the P-c(4450), has recently been observed in the J/psi p spectrum by the LHCb Collaboration. We discuss the feasibility of detecting this structure in J/psi photoproduction in the CLAS12 experiment at JLab. We present a first estimate of the upper limit for the branching ratio of the P-c (4450) to J/psi p. Our estimates, which take into account the experimental resolution effects, predict that it will be possible to observe a sizable cross section close to the J/psi production threshold and shed light on the P-c(4450) resonance in the future photoproduction measurements.
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Lami, A., & Roig, P. (2016). H -> ll ' in the simplest little Higgs model. Phys. Rev. D, 94(5), 056001–7pp.
Abstract: Little Higgs models are promising constructs to solve the hierarchy problem affecting the Higgs boson mass for generic new physics. However, their preservation of lepton universality forbids them to account for the H -> tau μCMS hint and at the same time respect (as they do) the severe limits on H -> μe inherited from the nonobservation of μ-> e gamma We compute the predictions of the simplest little Higgs model for the H -> ll' decays and conclude that the measurement of any of these decays at LHC (even with a much smaller rate than currently hinted) would, under reasonable assumptions, disfavor this model. This result is consistent with our earlier observation of very suppressed lepton flavor violating semileptonic tau decays within this model.
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Garcilazo, H., Valcarce, A., & Vijande, J. (2016). Doubly heavy baryon spectra guided by lattice QCD. Phys. Rev. D, 94(7), 074003–8pp.
Abstract: This paper provides results for the ground state and excited spectra of three-flavored doubly heavy baryons, bcn and bcs. We take advantage of the spin-independent interaction recently obtained to reconcile the lattice SU(3) QCD static potential and the results of nonperturbative lattice QCD for the triply heavy baryon spectra. We show that the spin-dependent potential might be constrained on the basis of nonperturbative lattice QCD results for the spin splittings of three-flavored doubly heavy baryons. Our results may also represent a challenge for future lattice QCD work, because a smaller lattice error could help in distinguishing between different prescriptions for the spin-dependent part of the interaction. Thus, by comparing with the reported baryon spectra obtained with parameters estimated from lattice QCD, one can challenge the precision of lattice calculations. The present work supports a coherent description of singly, doubly and triply heavy baryons with the same Cornell-like interacting potential. The possible experimental measurement of these states at LHCb is an incentive for this study.
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