ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Search for the Dimuon Decay of the Higgs Boson in pp Collisions at root s=13 TeV with the ATLAS Detector. Phys. Rev. Lett., 119(5), 051802–20pp.
Abstract: A search for the dimuon decay of the Higgs boson was performed using data corresponding to an integrated luminosity of 36.1 fb(-1) collected with the ATLAS detector in pp collisions at root s = 13 TeV at the Large Hadron Collider. No significant excess is observed above the expected background. The observed (expected) upper limit on the cross section times branching ratio is 3.0 (3.1) times the Standard Model prediction at the 95% confidence level for a Higgs boson mass of 125 GeV. When combined with the pp collision data at root s = 7 TeV and root s = 8 TeV, the observed (expected) upper limit is 2.8 (2.9) times the Standard Model prediction.
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Lubicz, V., Melis, A., & Simula, S. (2017). Masses and decay constants of D-(s)* and B-(s)* mesons with N-f=2+1+1 twisted mass fermions. Phys. Rev. D, 96(3), 034524–10pp.
Abstract: We present a lattice calculation of the masses and decay constants of D-(s)* and B-(s)* mesons using the gauge configurations produced by the European Twisted Mass Collaboration (ETMC) with N-f=2+1+1 dynamical quarks at three values of the lattice spacing a similar to(0.06-0.09) fm. Pion masses are simulated in the range M-pi similar or equal to(210-450) MeV, while the strange and charm sea-quark masses are close to their physical values. We compute the ratios of vector to pseudoscalar masses and decay constants for various values of the heavy-quark mass mh in the range 0.7m(c)(phys) less than or similar to m(h) less than or similar to 3m(c)(phys). In order to reach the physical b-quark mass, we exploit the Heavy Quark Effective Theory prediction that, in the static limit of infinite heavy-quark mass, the considered ratios are equal to one. At the physical point our results are: M-D*/M-D=1.0769(79), M-D*(s)/M-Ds=1.0751(56), f(D)*/f(D)=1.078(36), f(D)*s/f(Ds)=1.087(20), M-B*/M-B=1.0078(15), M-B*(s)/M-Bs=1.0083(10), f(B)*/f(B)=0.958(22) and f(B)*s/f(Bs)=0.974(10). Combining them with the experimental values of the pseudoscalar meson masses (used as input to fix the quark masses) and the values of the pseudoscalar decay constants calculated by ETMC, we get: M-D*=2013(14) MeV, M-D*(s)=2116(11) MeV, f(D)*=223.5(8.4) MeV, f(D)*(s)=268.8(6.6) MeV, M-B*=5320.5(7.6) MeV, M-B*(s)=5411.36(5.3) MeV, f(B)*=185.9(7.2) MeV and f(B)*(s)=223.1(5.4) MeV.
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Samart, D., Liang, W. H., & Oset, E. (2017). Triangle mechanisms in the build up and decay of the N*(1875). Phys. Rev. C, 96(3), 035202–14pp.
Abstract: We studied the N*(1875)(3/ 2-) resonance with a multichannel unitary scheme, considering the Delta pi and Sigma * K, with their interaction extracted from chiral Lagrangians, and then added two more channels, the N*(1535) p and N sigma, which proceed via triangle diagrams involving the Sigma * K and Delta pi respectively in the intermediate states. The triangle diagram in the N*(1535) p case develops a singularity at the same energy as the resonance mass. We determined the couplings of the resonance to the different channels and the partial decay widths. We found a very large decay width to Sigma * K, and also observed that, due to interference with other terms, the N sigma channel has an important role in the pi pi mass distributions at low invariant masses, leading to an apparently large N sigma decay width. We discuss justifying the convenience of an experimental reanalysis of this resonance, in light of the findings of the paper, using multichannel unitary schemes.
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T2K Collaboration(Abe, K. et al), Cervera-Villanueva, A., & Novella, P. (2017). Measurement of (nu)over-bar(mu) and nu(mu) charged current inclusive cross sections and their ratio with the T2K off-axis near detector. Phys. Rev. D, 96(5), 052001–15pp.
Abstract: We report a measurement of cross section sigma(nu(mu) + nucleus. -> mu(-) + X) and the first measurements of the cross section sigma((sigma) over bar (mu) + nucleus -> mu(+) + X) and their ratio R(sigma((nu) over bar)sigma(nu)) at (anti) neutrino energies below 1.5 GeV. We determine the single momentum bin cross section measurements, averaged over the T2K (nu) over bar/nu-flux, for the detector target material (mainly carbon, oxygen, hydrogen and copper) with phase space restricted laboratory frame kinematics of theta(mu) < 32 degrees and p(mu) > 500 MeV/c. The results are sigma((nu) over bar) = (0.900 +/- 0.029d (stat) +/- 0.088(syst) x 10(-39) and sigma(nu) = (2.41 +/- 0.022(stat) +/- 0.231(syst)) x 10(-39) in units of cm(2)/nucleon and R(sigma((nu) over bar)/sigma(nu) = 0.373 +/- 0.012(stat) +/- 0.015(syst).
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Afonso, V. I., Olmo, G. J., & Rubiera-Garcia, D. (2017). Scalar geons in Born-Infeld gravity. J. Cosmol. Astropart. Phys., 08(8), 031–35pp.
Abstract: The existence of static, spherically symmetric, self-gravitating scalar field solutions in the context of Born-Infeld gravity is explored. Upon a combination of analytical approximations and numerical methods, the equations for a free scalar field (without a potential term) are solved, verifying that the solutions recover the predictions of General Relativity far from the center but finding important new effects in the central regions. We find two classes of objects depending on the ratio between the Schwarzschild radius and a length scale associated to the Born-Infeld theory: massive solutions have a wormhole structure, with their throat at r = 2 M, while for the lighter configurations the topology is Euclidean. The total energy density of these solutions exhibits a solitonic profile with a maximum peaked away from the center, and located at the throat whenever a wormhole exists. The geodesic structure and curvature invariants are analyzed for the various configurations considered.
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