Carleton University

About: Carleton University is a education organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 15852 authors who have published 39650 publications receiving 1106610 citations.

The Exotic XYZ Charmonium-Like Mesons

Abstract: Charmonium, the spectroscopy of mesons, has recently enjoyed a renaissance with the discovery of several missing states and numerous unexpected charmonium-like resonances. These discoveries were made possible by the extremely large data samples made available by the B factories at SLAC and KEK, as well as CESR. Conventional states are well described by quark potential models; however, many of the newly discovered charmonium-like mesons do not seem to fit into the conventional spectrum. There is growing evidence that at least some of these new states are exotic, e.g., new forms of hadronic matter such as mesonic molecules, tetraquarks, and/or hybrid mesons. In this review we describe expectations for the properties of conventional charmonium states and the predictions for molecules, tetraquarks, and hybrids and the various processes that produce them. We examine the evidence for the new candidate exotic mesons, possible explanations, and experimental measurements that might reveal the nature of these states.

Search for Higgs boson pair production in the γ γ bb¯ final state with 13 TeV pp collision data collected by the ATLAS experiment

Abstract: A search is performed for resonant and non-resonant Higgs boson pair production in the $ \upgamma \upgamma b\overline{b} $ final state. The data set used corresponds to an integrated luminosity of 36.1 fb$^{−1}$ of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. No significant excess relative to the Standard Model expectation is observed. The observed limit on the non-resonant Higgs boson pair cross-section is 0.73 pb at 95% confidence level. This observed limit is equivalent to 22 times the predicted Standard Model cross-section. The Higgs boson self-coupling (κ$_{λ}$ = λ$_{HHH}$/λ$_{HHH}^{SM}$ ) is constrained at 95% confidence level to −8.2 < κ$_{λ}$ < 13.2. For resonant Higgs boson pair production through $ X\to HH\to \upgamma \upgamma b\overline{b} $ , the limit is presented, using the narrow-width approximation, as a function of m$_{X}$ in the range 260 GeV < m$_{X}$ < 1000 GeV. The observed limits range from 1.1 pb to 0.12 pb over this mass range.

Deficits of escape performance following catecholamine depletion: implications for behavioral deficits induced by uncontrollable stress.

Abstract: Following exposure to inescapable shock, mice exhibit deficits of escape performance, which are progressively more pronounced as training continues. Comparable effects were produced by DA and NE depletion by α-MpT and reserpine, NE depletion by FLA-63, and DA receptor blockade through haloperidol. Treatment with PCPA or 5-HTP did not influence performance. The disruptive effects of reserpine and α-MpT, as well as haloperidol and FLA-63, were additive. Unexpectedly, mice that received both reserpine and FLA-63 exhibited escape latencies that were significantly lower than those of mice that received either treatment alone. Consistent with the view that increased DA synthesis in the reserpine plus FLA-63 condition prevented the escape interference, L-DOPA antagonized the effects of both α-MpT and FLA-63. The results suggest that DA and NE act in a serial fashion to produce the escape deficits. Moreover, although both newly synthesized and previously stored amines contribute to the interference, the short latency responses seen during initial test trials could not be ascribed to previously stored amines.