Azimuthal anisotropy of dijet events in PbPb collisions at √s\u3csub\u3eNN\u3c/sub\u3e = 5.02 TeV

The path-length dependent parton energy loss within the dense partonic medium created in lead-lead collisions at a nucleon-nucleon center-of-mass energy of √sNN = 5.02TeV is studied by determining the azimuthal anisotropies for dijets with high transverse momentum. The data were collected by the CMS experiment in 2018 and correspond to an integrated luminosity of 1.69 nb−1. For events containing back-toback jets, correlations in relative azimuthal angle and pseudorapidity (η) between jets and hadrons, and between two hadrons, are constructed. The anisotropies are expressed as the Fourier expansion coefficients vn, n = 2–4 of these azimuthal distributions. The dijet vn values are extracted from long-range (1.5 \u3c |Δη| \u3c 2.5) components of these correlations, which suppresses the background contributions from jet fragmentation processes. Positive dijet v2 values are observed which increase from central to more peripheral events, while the v3 and v4 values are consistent with zero within experimental uncertainties

Search for Flavor-Changing Neutral Current Interactions of the Top Quark and Higgs Boson in Final States with Two Photons in Proton-Proton Collisions at √s =13 TeV

Proton-proton interactions resulting in final states with two photons are studied in a search for the signature of flavor-changing neutral current interactions of top quarks (t) and Higgs bosons (H). The analysis is based on data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb−1. No significant excess above the background prediction is observed. Upper limits on the branching fractions (Ɓ) of the top quark decaying to a Higgs boson and an up (u) or charm (c) quark are derived through a binned fit to the diphoton invariant mass spectrum. The observed (expected) 95% confidence level upper limits are found to be 0.019% (0.031%) for Ɓ(t → Hu) and 0.073% (0.051%) for Ɓ(t → Hc). These are the strictest upper limits yet determined

Search for higgsinos decaying to two Higgs bosons and missing transverse momentum in proton-proton collisions at √s = 13 TeV

Results are presented from a search for physics beyond the standard model in proton-proton collisions at √s = 13TeV in channels with two Higgs bosons, each decaying via the process H ⟶ b[], and large missing transverse momentum. The search uses a data sample corresponding to an integrated luminosity of 137 fb−1 collected by the CMS experiment at the CERN LHC. The search is motivated by models of supersymmetry that predict the production of neutralinos, the neutral partners of the electroweak gauge and Higgs bosons. The observed event yields in the signal regions are found to be consistent with the standard model background expectations. The results are interpreted using simplified models of supersymmetry. For the electroweak production of nearly mass-degenerate higgsinos, each of whose decay chains yields a neutralino ([]01 ) that in turn decays to a massless goldstino and a Higgs boson, []01 masses in the range 175 to 1025 GeV are excluded at 95% confidence level. For the strong production of gluino pairs decaying via a slightly lighter []02 to H and a light []01, gluino masses below 2330 GeV are excluded