{Search for direct production of GeV-scale resonances decaying to a pair of muons in proton-proton collisions at s \sqrt{s} = 13 TeV}

A search for direct production of low-mass dimuon resonances is performed using = 13 TeV proton-proton collision data collected by the CMS experiment during the 2017–2018 operation of the CERN LHC with an integrated luminosity of 96.6 fb−1. The search exploits a dedicated high-rate trigger stream that records events with two muons with transverse momenta as low as 3 GeV but does not include the full event information. The search is performed by looking for narrow peaks in the dimuon mass spectrum in the ranges of 1.1–2.6 GeV and 4.2–7.9 GeV. No significant excess of events above the expectation from the standard model background is observed. Model-independent limits on production rates of dimuon resonances within the experimental fiducial acceptance are set. Competitive or world’s best limits are set at 90% confidence level for a minimal dark photon model and for a scenario with two Higgs doublets and an extra complex scalar singlet (2HDM+S). Values of the squared kinetic mixing coefficient ε2 in the dark photon model above 10−6 are excluded over most of the mass range of the search. In the 2HDM+S, values of the mixing angle sin(θH) above 0.08 are excluded over most of the mass range of the search with a fixed ratio of the Higgs doublets vacuum expectation tan β = 0.5

Quarkonium measurements in nucleus-nucleus collisions with ALICE

Quarkonia, i.e. bound states of b (b) over bar and c (c) over bar quarks, are powerful observables to study the properties of nuclear matter under extreme conditions. The formation of a Quark-Gluon Plasma (QGP), which is predicted by lattice QCD calculations at high temperatures as reached at the LHC energies, has a strong influence on the production and behavior of quarkonia. The latest ALICE results on bottomonium and charmonium production in nucleus-nucleus collisions are presented. This includes measurements of the gamma(1S) and gamma(2S) nuclear modification factor (R-AA) at forward rapidity and the J/psi R-AA and v(2) as a function of centrality, P-T and rapidity in Pb-Pb collisions at root S-NN = 5.02 TeV. Also, first results from J/psi measurements in Xe-Xe collisions at root S-NN = 5.44 TeV are presented. Further on, the experimental results are compared to various calculations from theoretical models

Quarkonium measurements in nucleus-nucleus collisions with ALICE

Quarkonia, i.e. bound states of b (b) over bar and c (c) over bar quarks, are powerful observables to study the properties of nuclear matter under extreme conditions. The formation of a Quark-Gluon Plasma (QGP), which is predicted by lattice QCD calculations at high temperatures as reached at the LHC energies, has a strong influence on the production and behavior of quarkonia. The latest ALICE results on bottomonium and charmonium production in nucleus-nucleus collisions are presented. This includes measurements of the gamma(1S) and gamma(2S) nuclear modification factor (R-AA) at forward rapidity and the J/psi R-AA and v(2) as a function of centrality, P-T and rapidity in Pb-Pb collisions at root S-NN = 5.02 TeV. Also, first results from J/psi measurements in Xe-Xe collisions at root S-NN = 5.44 TeV are presented. Further on, the experimental results are compared to various calculations from theoretical models