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Wang, E., Xie, J. J., & Oset, E. (2016). chi(c0)(1P) decay into (Sigma)over-bar Sigma pi search of an I=1, 1/2(-) baryon state around (K)over-barN threshold. Phys. Lett. B, 753, 526–532.
Abstract: We present the theoretical study of the process chi(c0)(1P) -> (Sigma) over bar Sigma pi decay, by taking into account the pi Sigma and pi(Sigma) over bar final state interactions of the final meson-baryon pair based on the chiral unitary approach. We show that the process filters the isospin I = 1 in the pi Sigma channel and offers a reaction to test the existence of an I = 1 state with strangeness S = -1 and spin-parity J(p) = 1/2(-) around the (K) over barN threshold predicted by some theories and supported by some experiments.
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Camarero, D., de Azcarraga, J. A., & Izquierdo, J. M. (2017). Bosonic D=11 supergravity from a generalized Chern-Simons action. Nucl. Phys. B, 923, 633–652.
Abstract: It is shown that the action of the bosonic sector of D= 11supergravity may be obtained by means of a suitable scaling of the originally dimensionless fields of a generalized Chern-Simons action. This follows from the eleven-form CS-potential of the most general linear combination of closed, gauge invariant twelve-forms involving the sp(32)-valued two-form curvatures supplemented by a three-form field. In this construction, the role of the skewsymmetric four-index auxiliary function needed for the first order formulation of D= 11supergravity is played by the gauge field associated with the five Lorentz indices generator of the bosonic sp(32) subalgebra of osp(1|32).
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Wang, E., Chen, H. X., Geng, L. S., Li, D. M., & Oset, E. (2016). Hidden-charm pentaquark state in Lambda(0)(b) -> J/psi p pi(-) decay. Phys. Rev. D, 93(9), 094001–10pp.
Abstract: We study here the A(b)(0) -> J/psi p pi(-) reaction in analogy to the A(b)(0) -> J/psi pK(-) one, and we note that in both decays there is a sharp structure (dip or peak) in the J/psi p mass distribution around 4450 MeV, which is associated in the A(b)(0) -> J/psi pK(-) experiment to an exotic pentaquark baryonic state, although in J/psi p pi(-) it shows up with relatively low statistics. We analyze the A(b)(0) -> J/psi p pi(-) interaction along the same lines as the A(b)(0) -> J/psi pK(-) one, with the main difference stemming from the reduced Cabibbo strength in the former and the consideration of the pi(-)p final state interaction instead of the K(-)p one. We find that with a minimal input, introducing the pi(-)p and J/psi p interaction in S-wave with realistic interactions, and the empirical P-wave and D-wave contributions, one can accomplish a qualitative description of the pi(-)p and J/psi p mass distributions. More importantly, the peak structure followed by a dip of the experimental J/psi p mass distribution is reproduced with the same input as used to describe the data of A(b)(0) -> J/psi pK(-) reaction. The repercussion for the triangular singularity mechanism, invoked in some works to explain the pentaquark peak, is discussed.
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Albaladejo, M., Nieves, J., Oset, E., Sun, Z. F., & Liu, X. (2016). Can X(5568) be described as a B-s pi, B(K)over-bar resonant state? Phys. Lett. B, 757, 515–519.
Abstract: The DO Collaboration has recently seen a resonant-like peak in the B-s pi invariant mass spectrum, claimed to be a new state called X(5568). Using a B-s pi-B (K) over bar coupled channel analysis, implementing unitarity, and with the interaction derived from Heavy Meson Chiral Perturbation Theory, we are able to reproduce the reported spectrum, with a pole that can be associated to the claimed X(5568) state, and with mass and width in agreement with the ones reported in the experimental analysis. However, if the T-matrix regularization is performed by means of a momentum cutoff, the value for the latter needed to reproduce the spectrum is Lambda = 2.80 +/- 0.04 GeV, which is much larger than a “natural” value Lambda similar or equal to 1 GeV. In view of this, it is difficult to interpret the nature of this new state. This state would not qualify as a resonance dynamically generated by the unitarity loops. Assuming the observed peak to correspond to a physical state, we make predictions for partners in the D, D*, and B* sectors. Their observation (or lack thereof) would shed light into this issue.
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ATLAS Collaboration(Aad, G. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2016). Measurements of Z gamma and Z gamma gamma production in pp collisions at root s=8 TeV with the ATLAS detector. Phys. Rev. D, 93(11), 112002–41pp.
Abstract: The production of Z bosons with one or two isolated high-energy photons is studied using pp collisions at root s = 8 TeV. The analyses use a data sample with an integrated luminosity of 20.3 fb(-1) collected by the ATLAS detector during the 2012 LHC data taking. The Z gamma and Z gamma gamma production cross sections are measured with leptonic (e(+) e(-), mu(+) mu(-), nu(nu) over bar) decays of the Z boson, in extended fiducial regions defined in terms of the lepton and photon acceptance. They are then compared to cross-section predictions from the Standard Model, where the sources of the photons are radiation off initial-state quarks and radiative Z-boson decay to charged leptons, and from fragmentation of final-state quarks and gluons into photons. The yields of events with photon transverse energy E-T > 250 GeV from l(+) l(-) gamma events and with E-T > 400 GeV from nu(nu) over bar gamma events are used to search for anomalous triple gauge-boson couplings ZZ gamma and Z gamma gamma. The yields of events with diphoton invariant mass m(gamma gamma) > 200 GeV from l(+) l(-) gamma gamma events and with m(gamma gamma) > 300 GeV from nu(nu) over bar gamma gamma events are used to search for anomalous quartic gauge-boson couplings ZZ gamma gamma and Z gamma gamma gamma. No deviations from Standard Model predictions are observed and limits are placed on parameters used to describe anomalous triple and quartic gauge-boson couplings.
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