LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., & Sanchez Mayordomo, C. (2017). Observation of eta(c)(2S) -> p(p)over-bar and search for X(3872) -> p(p)over-bar decays. Phys. Lett. B, 769, 305–313.
Abstract: The first observation of the decay eta(c)(2S) -> p (p) over bar is reported using proton -proton collision data corresponding to an integrated luminosity of 3.0 fb(-1) recorded by the LHCb experiment at centre -of -mass energies of 7 and 8 TeV. The eta c(2S) resonance is produced in the decay B+ [c (c) over bar ]K+. The product of branching fractions normalised to that for the intermediate state, R-eta c,(2s), is measured to be R-eta c,(2s) equivalent to B(B+-> eta c (2S)K+) x B(eta c(2s)(2S) -> p<<(p)over bar> )/B(B+ -> J/psi k(+)) x B(J/psi -> p<<(p)over bar> ) = (1.58 +/- 0.33 +/- 0.09) x 10(-2), where the first uncertainty is statistical and the second systematic. No signals for the decays B+ -> X(3872)(-> p (p) over bar )K+ and B+ psi(3770)(-> p (p) over bar )K+ are seen, and the 95% confidence level upper limits on their relative branching ratios are found to be R-x(3872) < 0.25 x 10(-2) and R-psi(3770) < 0.10. In addition, the mass differences between the nc(1S) and the J/psi states, between the eta(c)(2S) and the eta(c)(2S) states, and the natural width of the psi(1S) are measured as M-J/psi – M-eta c(7s)= 110.2 +/- 0.5 +/- 0.9 MeV, M psi(2S) – M-eta c (2S) = 52.5 +/- 1.7 +/- 0.6 MeV, Gamma(eta c) (1s) = 34.0 +/- 1.9 +/- 1.3 MeV.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Search for CP violation in the phase space of D-0 -> pi(+)pi(-)pi(+)pi(-) decays. Phys. Lett. B, 769, 345–356.
Abstract: A search for time-integrated CP violation in the Cabibbo-suppressed decay D-0 -> pi(+)pi(-)pi(+)pi(-) is performed using an unbinned, model-independent technique known as the energy test. This is the first application of the energy test in four-body decays. The search is performed for P-even CP asymmetries and, for the first time, is extended to probe the P-odd case. Using proton proton collision data corresponding to an integrated luminosity of 3.0 fb(-1) collected by the LHCb detector at centre-of-mass energies of root s = 7 TeV and 8 TeV, the world's best sensitivity to CP violation in this decay is obtained. The data are found to be consistent with the hypothesis of CP symmetry with a p-value of (4.6 +/- 0.5)% in the P-even case, and marginally consistent with a p-value of (0.6 +/- 0.2)% in the P-odd case, corresponding to a significance for CP non -conservation of 2.7 standard deviations.
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NA48/2 Collaboration(Batley, J. R. et al), & Fiorini, L. (2017). Searches for lepton number violation and resonances in K-+/- -> pi μμdecays. Phys. Lett. B, 769, 67–76.
Abstract: The NA48/2 experiment at CERN collected a large sample of charged kaon decays to final states with multiple charged particles in 2003-2004. A new upper limit on the rate of the lepton number violating decay K-+/- -> pi(+/-)mu(+/-)mu(+/-) is reported: B( K-+/- -> pi(+/-)mu(+/-)mu(+/-)) < 8.6 x 10(-11) at 90% CL. Searches for two-body resonances X in K-+/- -> pi μμdecays (such as heavy neutral leptons N-4 and inflatons chi) are also presented. In the absence of signals, upper limits are set on the products of branching fractions B(K-+/- -> μN-+/-(4))B(N-4 -> pi mu) and B(K-+/- ->pi X-+/-)B(X -> mu(+),mu(-)) for ranges of assumed resonance masses and lifetimes. The limits are in the (10(-11),10(-9)) range for resonance lifetimes below 100 ps.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Measurement of the cross section for inclusive isolated-photon production in pp collisions at root s=13 TeV using the ATLAS detector. Phys. Lett. B, 770, 473–493.
Abstract: Inclusive isolated-photon production in pp collisions at a centre-of-mass energy of 13 TeV is studied with the ATLAS detector at the LHC using a data set with an integrated luminosity of 3.2 fb(-1). The cross section is measured as a function of the photon transverse energy above 125 GeV in different regions of photon pseudorapidity. Next-to-leading-order perturbative QCD and Monte Carlo event-generator predictions are compared to the cross-section measurements and provide an adequate description of the data.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Measurement of CP asymmetries in D-+/- -> eta 'pi(+/-) and D-S(+/-) -> eta 'pi(+/-) decays. Phys. Lett. B, 771, 21–30.
Abstract: A search for CP violation in D-+/- -> eta 'pi(+/-) and D-S(+/-) -> eta 'pi(+/-) decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 3 fb(-1), recorded by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The measured CP-violating charge asymmetries are A(CP)(D-+/- -> eta 'pi(+/-)) = (-0.61 +/- 0.72 +/- 0.53 +/- 0.12)% and A(CP)(D-S(+/-) -> eta 'pi(+/-)) = (-0.82 +/- 0.36 +/- 0.22 +/- 0.27)%, where the first uncertainties are statistical, the second systematic, and the third are the uncertainties on the A(CP)(D-+/- -> K-S(0)pi(+/-)) and A(CP)(D-S(+/-) -> phi pi(+/-)) measurements used for calibration. The results represent the most precise measurements of these asymmetries to date.
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