LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). Measurement of forward Z -> e(+)e(-) production at root s=8 TeV. J. High Energy Phys., 05(5), 109–21pp.
Abstract: A measurement of the cross-section for Z-boson production in the forward region of pp collisions at 8 TeV centre-of-mass energy is presented. The measurement is based on a sample of Z -> e(+)e(-) decays reconstructed using the LHCb detector, corresponding to an integrated luminosity of 2.0 fb(-1). The acceptance is defined by the requirements 2.0 < eta < 4.5 and p(T) > 20 GeV for the pseudorapidities and transverse momenta of the leptons. Their invariant mass is required to lie in the range 60-120 GeV. The cross-section is determined to be sigma(pp -> Z -> e(+)e(-)) = 93.81 +/- 0.41(stat) +/- 1.48(syst) +/- 1.14(lumi) pb, where the first uncertainty is statistical and the second reflects all systematic effects apart from that arising from the luminosity, which is given as the third uncertainty. Differential cross-sections are presented as functions of the Z-boson rapidity and of the angular variable phi*, which is related to the Z-boson transverse momentum.
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Bayar, M., Ren, X. L., & Oset, E. (2015). States of rho D*(D)over-bar* with J=3 within the fixed center approximation to the Faddeev equations. Eur. Phys. J. A, 51(5), 61–9pp.
Abstract: We study the interaction of rho, D* and (D) over bar* with spins aligned using the fixed center approximation to the Faddeev equations. We select a cluster of D*(D) over bar*, which is found to be bound in I = 0 and can be associated to the X(3915), and let the rho meson orbit around the D* and (D) over bar*. In this case we find an I = 1 state with mass around 4340 MeV and narrow width of about 50MeV. We also investigate the case with a cluster of rho D* and let the (D) over bar * orbit around the system of the two states. The rho D* cluster is also found to bind and leads to the D-2*(2460) state. The addition of the extra (D) over bar* produces further binding and we find, with admitted uncertainties, a state of I = 0 around 4000MeV, and a less bound narrow state with I = 1 around 4200 MeV.
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Taprogge, J. et al, Gadea, A., & Montaner-Piza, A. (2015). beta decay of Cd-129 and excited states in In-129. Phys. Rev. C, 91(5), 054324–11pp.
Abstract: The beta decay of Cd-129, produced in the relativistic fission of a U-238 beam, was experimentally studied at the RIBF facility at the RIKEN Nishina Center. From the gamma radiation emitted after the beta decays, a level scheme of In-129 was established comprising 31 excited states and 69 gamma-ray transitions. The experimentally determined level energies are compared to state-of-the-art shell-model calculations. The half-lives of the two beta-decaying states in Cd-129 were deduced and the beta feeding to excited states in In-129 were analyzed. It is found that, as in most cases in the Z < 50, N <= 82 region, both decays are dominated by the nu 0g(7/2) -> pi 0g(9/2) Gamow-Teller transition, although the contribution of first-forbidden transitions cannot be neglected.
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Martinez Torres, A., Oset, E., Prelovsek, S., & Ramos, A. (2015). Reanalysis of lattice QCD spectra leading to the Ds0*(2317) and Ds1*(2460). J. High Energy Phys., 05(5), 153–22pp.
Abstract: We perform a reanalysis of the energy levels obtained in a recent lattice QCD simulation, from where the existence of bound states of KD and KD* are induced and identified with the narrow D-s0*(2317) and D-s1*(2460) resonances. The reanalysis is done in terms of an auxiliary potential, employing a single-channel basis KD(*()), and a two-channel basis KD(*()), eta D-s(()*()). By means of an extended Luscher method we determine poles of the continuum t-matrix, bound by about 40 MeV with respect to the KD and KD* thresholds, which we identify with the D-s0*(2317) and D-s1*(2460) resonances. Using a sum rule that reformulates Weinberg compositeness condition we can determine that the state D-s0*(2317) contains a KD component in an amount of about 70%, while the state D-s1*(2460) contains a similar amount of KD*. We argue that the present lattice simulation results do not still allow us to determine which are the missing channels in the bound state wave functions and we discuss the necessary information that can lead to answer this question.
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Fuster, J., Garcia, I., Gomis, P., Perello, M., Ros, E., & Vos, M. (2015). Study of single top production at high energy electron positron colliders. Eur. Phys. J. C, 75(5), 223–7pp.
Abstract: The effect of single top production on the study of top quark pair production in future high energy electron-positron colliders is evaluated. The rate of the single top quark production process is sizeable throughout a large range of center-of-mass energies and the final state cannot easily be distinguished from the dominant pair production process. We discuss the impact on the top quark mass extraction from a scan through the pair production threshold and the determination of top quark form factors in the continuum. These results advocate for the exploration of the inclusive e(+) e(-) -> W(+)bW(-)b(-) process, that includes both top quark pair and single top quark production.
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