Liang, W. H., Albaladejo, M., & Oset, E. (2013). Searching for a hidden charm h(1) state in the X(4660) -> eta h(1) and X(4660) -> eta D*(D)over-bar* decays. Phys. Rev. D, 88(7), 074027–7pp.
Abstract: We explore the possibility of experimentally detecting a predicted h(1) inverted right perpendicular I-G(J(PC)) = 0(-)(1(+-))inverted left perpendicular state of hidden charm made out from the D*(D) over bar* interaction. The method consists in measuring the decay of X(4660) into eta D*(D) over bar* and determining the binding energy with respect to the D*(D) over bar* threshold from the shape of the D*(D) over bar* invariant mass distribution. A complementary method consists in looking at the inclusive X(4660) -> eta X decay and searching for a peak in the X invariant mass distribution. We make calculations to determine the partial decay width of X(4660) -> eta h(1) from the measured X(4660) -> eta D*(D) over bar* distribution. This estimation should serve in an experiment to foresee the possibility of detecting the h(1) state on top of the background of inclusive events.
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Helo, J. C., Kovalenko, S. G., Hirsch, M., & Pas, H. (2013). Short-range mechanisms of neutrinoless double beta decay at the LHC. Phys. Rev. D, 88(7), 073011–19pp.
Abstract: Lepton number violation (LNV) mediated by short- range operators can manifest itself in both neutrinoless double beta decay (0 nu beta beta) and in processes with same- sign dilepton final states at the LHC. We derive limits from existing LHC data at root s = 8 TeV and compare the discovery potential of the forthcoming root s = 14 TeV phase of the LHC with the sensitivity of current and future 0 nu beta beta decay experiments, assuming the short-range part of the 0 nu beta beta decay amplitude dominates. We focus on the first of two possible topologies triggered by one fermion and two bosons in the intermediate state. In all cases, except for the pure leptoquark mechanism, the LHC will be more sensitive than 0 nu beta beta decay in the future. In addition, we propose to search for a charge asymmetry in the final state leptons and to use different invariant mass peaks as a possible tool to discriminate the various possible mechanisms for LNV signals at the LHC.
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Dehnadi, B., Hoang, A. H., Mateu, V., & Zebarjad, S. M. (2013). Charm mass determination from QCD charmonium sum rules at order alpha(3)(s). J. High Energy Phys., 09(9), 103–56pp.
Abstract: We determine the (MS) over bar charm quark mass from a charmonium QCD sum rules analysis. On the theoretical side we use input from perturbation theory at O (alpha(3)(s)). Improvements with respect to previous O (alpha(3)(s)) analyses include (1) an account of all available e(+)e(-) hadronic cross section data and (2) a thorough analysis of perturbative uncertainties. Using a data clustering method to combine hadronic cross section data sets from di ff erent measurements we demonstrate that using all available experimental data up to c. m. energies of 10 : 538 GeV allows for determinations of experimental moments and their correlations with small errors and that there is no need to rely on theoretical input above the charmonium resonances. We also show that good convergence properties of the perturbative series for the theoretical sum rule moments need to be considered with some care when extracting the charm mass and demonstrate how to set up a suitable set of scale variations to obtain a proper estimate of the perturbative uncertainty. As the fi nal outcome of our analysis we obtain (m(c)) over bar((m(c)) over bar) = 1 : 282 +/- (0.009)(stat) +/- (0.009)(syst) +/- (0.019)(pert) +/- (0.010)(alpha s) +/- (0.002)(< GG >) GeV. The perturbative error is an order of magnitude larger than the one obtained in previous O (alpha(3)(s)) sum rule analyses.
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NOMAD Collaboration(Samoylov, O. et al), Cervera-Villanueva, A., Gomez-Cadenas, J. J., & Hernando, J. (2013). A precision measurement of charm dimuon production in neutrino interactions from the NOMAD experiment. Nucl. Phys. B, 876(2), 339–375.
Abstract: We present our new measurement of the cross-section for charm dimuon production in neutrino iron interactions based upon the full statistics collected by the NOMAD experiment. After background subtraction we observe 15 344 charm dimuon events, providing the largest sample currently available. The analysis exploits the large inclusive charged current sample – about 9 x 10(6) events after all analysis cuts – and the high resolution NOMAD detector to constrain the total systematic uncertainty on the ratio of charm dimuon to inclusive Charged Current (CC) cross-sections to similar to 2%. We also perform a fit to the NOMAD data to extract the charm production parameters and the strange quark sea content of the nucleon within the NLO QCD approximation. We obtain a value of m(c)(m(c)) = 1.159 +/- 0.075 GeV/c(2) for the running mass of the charm quark in the (MS) over bar scheme and a strange quark sea suppression factor of kappa(s) = 0.591 +/- 0.019 at Q(2) = 20 GeV2/c(2).
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Bayar, M., & Oset, E. (2013). (K)over-bar N N absorption within the framework of the fixed-center approximation to Faddeev equations. Phys. Rev. C, 88(4), 044003–8pp.
Abstract: We present a method to evaluate the (K) over bar absorption width in the bound (K) over bar N N system. Most calculations of this system ignore this channel and only consider the (K) over bar N -> pi Sigma conversion. Other works make a qualitative calculation using perturbative methods. Since the (1405) resonance is playing a role in the process, the same resonance is changed by the presence of the absorption channels andwe find that a full nonperturbative calculation is called for, which we present here. We employ the fixed center approximation to Faddeev equations to account for (K) over bar rescattering on the (NN) cluster and we find that the width of the states found previously for S = 0 and S = 1 increases by about 30 MeV due to the (K) over bar N N absorption, to a total width of about 80 MeV.
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