A search for physics beyond the standard model in the final state with two same-flavour leptons (electrons or muons) and two quarks produced in proton-proton collisions at sqrt(s) = 13 TeV is presented. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 2.3 inverse femtobarns. The observed data are in good agreement with the standard model background prediction. The results of the measurement are interpreted in the framework of a recently proposed model in which a heavy Majorana neutrino, N(l), stems from a composite-fermion scenario. Exclusion limits are set for the first time on the mass of the heavy composite Majorana neutrino, m[N(l)], and the compositeness scale Lambda. For the case m[N(l)] = Lambda, the existence of N(e) (N(mu)) is excluded for masses up to 4.60 (4.70) TeV at 95% confidence level.
Invariant mass distribution of two electrons and one large-radius jet. The events are selected accordingly to the signal region slection in the electron channel described in the paper.
Invariant mass distribution of two muons and one large-radius jet. The events are selected accordingly to the signal region slection in the muon channel described in the paper.
95% CL upper limits on the product of the production cross section $\sigma(pp\to N_e)$ and the branching ratio $B(N_e \to e q \bar{q}^{\prime})$ in electron channel, compared with theoretical predictions for HCMN model calculated with CalcHEP.
Two searches for new phenomena in final states containing a same-flavour opposite-lepton (electron or muon) pair, jets, and large missing transverse momentum are presented. These searches make use of proton--proton collision data, collected during 2015 and 2016 at a centre-of-mass energy $\sqrt{s}=13$ TeV by the ATLAS detector at the Large Hadron Collider, which correspond to an integrated luminosity of 14.7 fb$^{-1}$. Both searches target the pair production of supersymmetric particles, squarks or gluinos, which decay to final states containing a same-flavour opposite-sign lepton pair via one of two mechanisms: a leptonically decaying Z boson in the final state, leading to a peak in the dilepton invariant-mass distribution around the Z boson mass; and decays of neutralinos (e.g. $\tilde{\chi}_2^0 \rightarrow \ell^+\ell^- \tilde{\chi}_1^0$), yielding a kinematic endpoint in the dilepton invariant-mass spectrum. The data are found to be consistent with the Standard Model expectation. Results are interpreted in simplified models of gluino-pair (squark-pair) production, and provide sensitivity to gluinos (squarks) with masses as large as 1.70 TeV (980 GeV).
Dilepton invariant mass distribution in SRZ.
Dilepton transverse momentum distribution in SRZ.
Missing transverse momentum distribution in SRZ.
The cross section for $e^+ e^- \to \pi^+ \pi^- J/\psi$ between 3.8 GeV and 5.5 GeV is measured with a 967 fb$^{-1}$ data sample collected by the Belle detector at or near the $\Upsilon(nS)$ ($n = 1,\ 2,\ ...,\ 5$) resonances. The Y(4260) state is observed, and its resonance parameters are determined. In addition, an excess of $\pi^+ \pi^- J/\psi$ production around 4 GeV is observed. This feature can be described by a Breit-Wigner parameterization with properties that are consistent with the Y(4008) state that was previously reported by Belle. In a study of $Y(4260) \to \pi^+ \pi^- J/\psi$ decays, a structure is observed in the $M(\pi^\pm\jpsi)$ mass spectrum with $5.2\sigma$ significance, with mass $M=(3894.5\pm 6.6\pm 4.5) {\rm MeV}/c^2$ and width $\Gamma=(63\pm 24\pm 26)$ MeV/$c^{2}$, where the errors are statistical and systematic, respectively. This structure can be interpreted as a new charged charmonium-like state.
Measured cross section with statistical errors only.
The global topologies of inclusive three-- and four--jet events produced in $\pp$ interactions are described. The three-- and four--jet events are selected from data recorded by the D\O\ detector at the Tevatron Collider operating at a center--of--mass energy of $\sqrt{s} = 1800$ GeV. The measured, normalized distributions of various topological variables are compared with parton--level predictions of tree--level QCD calculations. The parton--level QCD calculations are found to be in good agreement with the data. The studies also show that the topological distributions of the different subprocesses involving different numbers of quarks are very similar and reproduce the measured distributions well. The parton shower Monte Carlo generators provide a less satisfactory description of the topologies of the three-- and four--jet events.
The estimated systematic uncertainty is 6 PCT.
The estimated systematic uncertainty is 6 PCT.
The estimated systematic uncertainty is 6 PCT.
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