The W boson helicity fractions from top quark decays in tt events are measured using data from proton-proton collisions at a centre-of-mass energy of 8 TeV. The data were collected in 2012 with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.8 fb −1 . Events are reconstructed with either one muon or one electron, along with four jets in the final state, with two of the jets being identified as originating from b quarks. The measured helicity fractions from both channels are combined, yielding F 0 = 0.681 ± 0.012 (stat) ± 0.023 (syst), F L = 0.323 ± 0.008 (stat) ± 0.014 (syst), and F R = −0.004 ± 0.005 (stat) ± 0.014 (syst) for the longitudinal, left-, and right-handed components of the helicity, respectively. These measurements of the W boson helicity fractions are the most accurate to date and they agree with the predictions from the standard model.

Abstract:The cross section for the production of Zγ in proton-proton collisions at 8 TeV is measured based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 19.5 fb −1 . Events with an oppositely-charged pair of muons or electrons together with an isolated photon are selected. The differential cross section as a function of the photon transverse momentum is measured inclusively and exclusively, where the exclusive selection applies a veto on central jets. The observed cross sections are compatible with the expectations of next-to-next-to-leading-order quantum chromodynamics. Limits on anomalous triple gauge couplings of ZZγ and Zγγ are set that improve on previous experimental results obtained with the charged lepton decay modes of the Z boson.

Measurement of the top quark mass in the dileptonic tt decay channel using the mass observables M b , M T2 , and M b ν in pp collisions at √ s = 8 TeVThe CMS Collaboration * AbstractA measurement of the top quark mass (M t ) in the dileptonic tt decay channel is performed using data from proton-proton collisions at a center-of-mass energy of 8 TeV. The data was recorded by the CMS experiment at the LHC and corresponds to an integrated luminosity of 19.7 ± 0.5 fb −1 . Events are selected with two oppositely charged leptons ( = e, µ) and two jets identified as originating from b quarks. The analysis is based on three kinematic observables whose distributions are sensitive to the value of M t . An invariant mass observable, M b , and a 'stransverse mass' observable, M T2 , are employed in a simultaneous fit to determine the value of M t and an overall jet energy scale factor (JSF). A complementary approach is used to construct an invariant mass observable, M b ν , that is combined with M T2 to measure M t . The shapes of the observables, along with their evolutions in M t and JSF, are modeled by a nonparametric Gaussian process regression technique. The sensitivity of the observables to the value of M t is investigated using a Fisher information density method. The top quark mass is measured to be 172.22 ± 0.18 (stat) +0.89 −0.93 (syst) GeV. Published in Physical Review D asWe select dileptonic tt events from a data set recorded at √ s = 8 TeV during 2012 corresponding to an integrated luminosity of 19.7 ± 0.5 fb −1 [17]. Events are required to pass one of several triggers that require at least two leptons, ee, eµ, or µµ, where the leading (higher-p T ) lepton

A search for dark matter (DM) particles is performed using events with a Higgs boson candidate and large missing transverse momentum. The analysis is based on protonproton collision data at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC in 2016, corresponding to an integrated luminosity of 35.9 fb −1. The search is performed in five Higgs boson decay channels: h → bb, γγ, τ + τ − , W + W − , and ZZ. The results from the individual channels are combined to maximize the sensitivity of the analysis. No significant excess over the expected standard model background is observed in any of the five channels or in their combination. Limits are set on DM production in the context of two simplified models. The results are also interpreted in terms of a spin-independent DM-nucleon scattering cross section and compared to those from directdetection DM experiments. This is the first search for DM particles produced in association with a Higgs boson decaying to a pair of W or Z bosons, and the first statistical combination based on five Higgs boson decay channels.

By analyzing 482 pb −1 of e þ e − collision data collected at the center-of-mass energy ffiffi ffi s p ¼ 4.009 GeV with the BESIII detector, we measure the branching fractions for the semi-leptonic decays.06 AE 0.54 AE 0.07Þ%, where the first and second uncertainties are statistical and systematic, respectively. The branching fractions for the three semi-muonic decays D þ s → ϕμ þ ν μ ; ημ þ ν μ and η 0 μ þ ν μ are determined for the first time and that of D þ s → ϕe þ ν e is consistent with the world average value within uncertainties.