Mathieu, V., & Vento, V. (2010). eta-eta ' mixing in the flavor basis and large N. Phys. Lett. B, 688(4-5), 314–318.
Abstract: The mass matrix for eta-eta' is derived in the flavor basis at O(p(4)) of the chiral Lagrangian using the large N approximation. Under certain assumptions, the mixing angle phi = 41.4 degrees and the decay constants ratio f(K)/f(pi) = 1.15 are calculated in agreement with the data. It appears that the FKS scheme arises as a special limit of the chiral Lagrangian. Their mass matrix is obtained without the hypothesis on the mixing pattern of the decay constants.
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Cabrera, M. E., Casas, J. A., & Ruiz de Austri, R. (2010). MSSM forecast for the LHC. J. High Energy Phys., 05(5), 043–48pp.
Abstract: We perform a forecast of the MSSM with universal soft terms (CMSSM) for the LHC, based on an improved Bayesian analysis. We do not incorporate ad hoc measures of the fine-tuning to penalize unnatural possibilities: such penalization arises from the Bayesian analysis itself when the experimental value of M-Z is considered. This allows to scan the whole parameter space, allowing arbitrarily large soft terms. Still the low-energy region is statistically favoured (even before including dark matter or g-2 constraints). Contrary to other studies, the results are almost unaffected by changing the upper limits taken for the soft terms. The results are also remarkable stable when using flat or logarithmic priors, a fact that arises from the larger statistical weight of the low-energy region in both cases. Then we incorporate all the important experimental constrains to the analysis, obtaining a map of the probability density of the MSSM parameter space, i.e. the forecast of the MSSM. Since not all the experimental information is equally robust, we perform separate analyses depending on the group of observables used. When only the most robust ones are used, the favoured region of the parameter space contains a significant portion outside the LHC reach. This effect gets reinforced if the Higgs mass is not close to its present experimental limit and persits when dark matter constraints are included. Only when the g-2 constraint (based on e(+)e(-) data) is considered, the preferred region (for μ> 0) is well inside the LHC scope. We also perform a Bayesian comparison of the positive- and negative-mu possibilities.
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Martinez Torres, A., & Oset, E. (2010). The gamma d -> K(+)K(-)np reaction and an alternative explanation for the “Theta(+)(1540) pentaquark” peak. Phys. Rev. C, 81(5), 055202–16pp.
Abstract: We present a calculation of the gamma d -> K(+)K(-)np reaction with the aim of seeing whether the experimental peak observed in the K(+)n invariant mass around 1526 MeV, from where evidence for the existence of the Theta(+) has been claimed, can be obtained without this resonance as a consequence of the particular dynamics of the process and the cuts applied in the experimental setup. We find that a combination of facts leads indeed to a peak around 1530 MeV for the invariant mass of K(+)n without the need to invoke any new resonance around this energy. This, together with statistical fluctuations that we prove to be large with the statistics of the experiment, is likely to produce the narrower peak observed there.
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Barenboim, G. (2010). Gravity triggered neutrino condensates. Phys. Rev. D, 82(9), 093014–13pp.
Abstract: In this work we use the Schwinger-Dyson equations to study the possibility that an enhanced gravitational attraction triggers the formation of a right-handed neutrino condensate, inducing dynamical symmetry breaking and generating a Majorana mass for the right-handed neutrino at a scale appropriate for the seesaw mechanism. The composite field formed by the condensate phase could drive an early epoch of inflation. We find that to the lowest order, the theory does not allow dynamical symmetry breaking. Nevertheless, thanks to the large number of matter fields in the model, the suppression by additional powers in G of higher order terms can be compensated, boosting them up to their lowest order counterparts. This way chiral symmetry can be broken dynamically and the infrared mass generated turns out to be in the expected range for a successful seesaw scenario.
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Perez, A. (2010). Information encoding of a qubit into a multilevel environment. Phys. Rev. A, 81(5), 052326–6pp.
Abstract: I consider the interaction of a small quantum system (a qubit) with a structured environment consisting of many levels. The qubit will experience a decoherence process, which implies that part of its initial information will be encoded into correlations between system and environment. I investigate how this information is distributed on a given subset of levels as a function of its size, using the mutual information between both entities, in the spirit of the partial-information plots studied by Zurek and co-workers. In this case we can observe some differences, which arise from the fact that I am partitioning just one quantum system and not a collection of them. However, some similar features, like redundancy (in the sense that a given amount of information is shared by many subsets), which increases with the size of the environment, are also found here.
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Oset, E., & Ramos, A. (2010). Dynamically generated resonances from the vector octet-baryon octet interaction. Eur. Phys. J. A, 44(3), 445–454.
Abstract: We study the interaction of vector mesons with the octet of stable baryons in the framework of the local hidden gauge formalism using a coupled-channels unitary approach. We examine the scattering amplitudes and their poles, which can be associated to known J(P) = 1/2(-), 3/2(-) baryon resonances, in some cases, or give predictions in other ones. The formalism employed produces doublets of degenerate J(P) = 1/2(-), 3/2(-) states, a pattern which is observed experimentally in several cases. The findings of this work should also be useful to guide present experimental programs searching for new resonances, in particular in the strange sector where the current information is very poor.
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Liang, W. H., Molina, R., & Oset, E. (2010). Radiative open charm decay of the Y(3940), Z(3930), X(4160) resonances. Eur. Phys. J. A, 44(3), 479–486.
Abstract: We determine the radiative decay amplitudes for the decay into D* and (D) over bar gamma, or (D) over bar gamma(s)* and s. of some of the charmonium- like states classified as X, Y, Z resonances, plus some other hidden charm states which are dynamically generated from the interaction of vector mesons with charm. The mass distributions as a function of the (D) over bar gamma or (D) over bar (s)gamma. invariant mass show a peculiar behavior as a consequence of the D* (D) over bar gamma* nature of these states. The experimental search of these magnitudes can shed light on the nature of these states.
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Gonzalez-Alonso, M., Pich, A., & Prades, J. (2010). Violation of quark-hadron duality and spectral chiral moments in QCD. Phys. Rev. D, 81(7), 074007–10pp.
Abstract: We analyze the spectral moments of the V – A two-point correlation function. Using all known short-distance constraints and the most recent experimental data from tau decays, we determine the lowest spectral moments, trying to assess the uncertainties associated with the so-called violations of quark-hadron duality. We have generated a large number of acceptable spectral functions, satisfying all conditions, and have used them to extract the wanted hadronic parameters through a careful statistical analysis. We obtain accurate values for the chi PT couplings L-10 and C-87, and a realistic determination of the dimension six and eight contributions in the operator product expansion, O-6 = (-5.4(-1.6)(+3.6)) . 10(-3) GeV6 and O-8 = d(-8.9-(12.6)(7.4+)) 10(-3) GeV8, showing that the duality-violation effects have been underestimated in previous literature.
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Morisi, S., & Peinado, E. (2010). S-4 model for quarks and leptons with maximal atmospheric angle. Phys. Rev. D, 81(8), 085015–8pp.
Abstract: We consider a model for quark and lepton masses and mixings based on S-4 flavor symmetry. The model contains six Higgs doublets where three of them give mass to the leptons, and the other three gives mass to the quarks. Charged fermion and quark masses arise from renormalizable interactions while neutrino Majorana masses are generated through effective dimension five Weinberg operator. From the study of the minimization of the scalar potential we found a residual μ<-> tau symmetry in the neutrino sector predicting zero reactor angle and maximal atmospheric angle and for the quark sector we found a four-zero texture. We give a fit of the mass hierarchies and mixing angles in the quark sector.
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Bandos, I. A., de Azcarraga, J. A., & Meliveo, C. (2011). Extended supersymmetry in massless conformal higher spin theory. Nucl. Phys. B, 853(3), 760–776.
Abstract: We propose superfield equations in tensorial N-extended superspaces to describe the N = 2,4,8 supersymmetric generalizations of free conformal higher spin theories. These can be obtained by quantizing a superparticle model in N-extended tensorial superspace. The N-extended higher spin supermultiplets just contain scalar and 'spinor' fields in tensorial space so that, in contrast with the standard (super)space approach, no nontrivial generalizations of the Maxwell or Einstein equations to tensorial space appear when N > 2. For N = 4,8, the higher spin-tensorial components of the extended tensorial superfields are expressed through additional scalar and spinor fields in tensorial space which obey the same free higher spin equations, but that are axion-like in the sense that they possess Peccei-Quinn-like symmetries.
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