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Foffa, S., Mastrolia, P., Sturani, R., Sturm, C., & Bobadilla, W. J. T. (2019). Static Two-Body Potential at Fifth Post-Newtonian Order. Phys. Rev. Lett., 122(24), 241605–6pp.
Abstract: We determine the gravitational interaction between two compact bodies up to the sixth power in Newton's constant, G(N), in the static limit. This result is achieved within the effective field theory approach to general relativity, and exploits a manifest factorization property of static diagrams which allows us to derive static post Newtonian (PN) contributions of (2n + 1) order in terms of lower order ones. We recompute in this fashion the 1PN and 3PN static potential, and present the novel 5PN contribution.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Barranco Navarro, L., Cabrera Urban, S., et al. (2019). Combination of Searches for Invisible Higgs Boson Decays with the ATLAS Experiment. Phys. Rev. Lett., 122(23), 231801–20pp.
Abstract: Dark matter particles, if sufficiently light, may be produced in decays of the Higgs boson. This Letter presents a statistical combination of searches for H -> invisible decays where H is produced according to the standard model via vector boson fusion, Z(ll)H, and W/Z(had)H, all performed with the ATLAS detector using 36.1 fb(-1) of pp collisions at a center-of-mass energy of root s = 13 TeV at the LHC. In combination with the results at root s = 7 and 8 TeV, an exclusion limit on the H -> invisible branching ratio of 0.26(0.17(-0.05)(+0.07)) at 95% confidence level is observed (expected).
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2019). Measurement of the Mass Difference Between Neutral Charm-Meson Eigenstates. Phys. Rev. Lett., 122(23), 231802–10pp.
Abstract: We report a measurement of the mass difference between neutral charm-meson eigenstates using a novel approach that enhances sensitivity to this parameter. We use 2.3 x 10(6) D-0 -> K-S(0)pi(+)pi(-) decays reconstructed in proton-proton collisions collected by the LHCb experiment in 2011 and 2012. Allowing for CP violation in mixing and in the interference between mixing and decay, we measure the CP-averaged normalized mass difference x(cp)= [2.7 +/- 1.6(stat) +/- 0.4(syst)] x 10(-3) and the CP-violating parameter Delta x = [-0.53 +/- 0.70(stat) +/- 0.22(syst)] x 10(-3). The results are consistent with CP symmetry. These determinations are the most precise from a single experiment and, combined with current world-average results, yield the fast evidence that the masses of the neutral charm-meson eigenstates differ.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2019). Observation of an Excited B-c(+) State. Phys. Rev. Lett., 122(23), 232001–10pp.
Abstract: Using pp collision data corresponding to an integrated luminosity of 8.5 fb(-1) recorded by the LHCb experiment at center-of-mass energies of root s = 7, 8, and 13 TeV, the observation of an excited B-c(+) state in the B-c(+)pi(+)pi(-) invariant-mass spectrum is reported. The observed peak has a mass of 6841.2 +/- 0.6(stat) +/- 0.1(syst) +/- 0.8(B-c(+)) MeV/c(2), where the last uncertainty is due to the limited knowledge of the B-c(+) mass. It is consistent with expectations of the B-c*(2(3)S(1))(+) state reconstructed without the low-energy photon from the B-c*(1(3)S(1))(+) -> B-c(+)gamma decay following B-c*(2(3)S(1))(+) -> B-c*(1(3)S(1))(+)pi(+)pi(-). A second state is seen with a global (local) statistical significance of 2.2 sigma (3.2 sigma) and a mass of 6872.1 +/- 1.3(stat) +/- 0.1(syst) +/- 0.8(B-c(+)) MeV/c(2), and is consistent with the B-c(2(1)S(0))(+) state. These mass measurements are the most precise to date.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2019). Observation of a Narrow Pentaquark State, P-c(4312)(+), and of the Two-Peak Structure of the P-c(4450)(+). Phys. Rev. Lett., 122(22), 222001–11pp.
Abstract: A narrow pentaquark state, P-c(4312)(+), decaying to J/psi p, is discovered with a statistical significance of 7.3 sigma in a data sample of Lambda(0)(b) -> J/psi pK(-) decays, which is an order of magnitude larger than that previously analyzed by the LHCb Collaboration. The P-c(4450)(+) pentaquark structure formerly reported by LHCb is confirmed and observed to consist of two narrow overlapping peaks, P-c(4440)(+) and P-c(4457)(+), where the statistical significance of this two-peak interpretation is 5.4 sigma. The proximity of the Sigma(+)(c)(D) over bar (0) and Sigma(+)(c)(D) over bar (*0) thresholds to the observed narrow peaks suggests that they play an important role in the dynamics of these states.
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