Precise measurement of RudsR_{\text{uds}} and RR between 1.84 and 3.72 GeV at the KEDR detector

The present work continues a series of the KEDR measurements of the $R$ value that started in 2010 at the VEPP-4M $e^+e^-$ collider. By combining new data with our previous results in this energy range we measured the values of $R_{\text{uds}}$ and $R$ at nine center-of-mass energies between 3.08 and 3.72 GeV. The total accuracy is about or better than $2.6\%$ at most of energy points with a systematic uncertainty of about $1.9\%$. Together with the previous precise $R$ measurement at KEDR in the energy range 1.84-3.05 GeV, it constitutes the most detailed high-precision $R$ measurement near the charmonium production threshold.Comment: arXiv admin note: text overlap with arXiv:1610.02827 and substantial text overlap with arXiv:1510.0266

Measurement of the branching fraction of J/ψ→ρπJ/\psi\rightarrow\rho\pi at KEDR

We present the study of the decay $J/\psi \rightarrow \rho \pi$. The results are based on of 5.2 million $J/\psi$ events collected by the KEDR detector at VEPP-4M collider. The branching fraction is measured to be $\mathcal{B}(J/\psi\rightarrow\rho\pi) = \big(2.072\pm 0.017 \pm 0.056 \big)\cdot 10^{-2}$ where the first uncertainty is statistical, the second one is systematic. This is the most precise single measurement of this quantity at the moment

Search for decays of the 125 GeV Higgs boson into a Z boson and a ρ or ϕ meson

Decays of the 125 GeV Higgs boson into a Z boson and a ρ^0(770) or ϕ(1020) meson are searched for using proton-proton collision data collected by the CMS experiment at the LHC at √s = 13 TeV. The analysed data set corresponds to an integrated luminosity of 137 fb⁻¹. Events are selected in which the Z boson decays into a pair of electrons or a pair of muons, and the ρ and ϕ mesons decay into pairs of pions and kaons, respectively. No significant excess above the background model is observed. As different polarization states are possible for the decay products of the Z boson and ρ or ϕ mesons, affecting the signal acceptance, scenarios in which the decays are longitudinally or transversely polarized are considered. Upper limits at the 95% confidence level on the Higgs boson branching fractions into Zρ and Zϕ are determined to be 1.04–1.31% and 0.31–0.40%, respectively, where the ranges reflect the considered polarization scenarios; these values are 740–940 and 730–950 times larger than the respective standard model expectations. These results constitute the first experimental limits on the two decay channels

Observation of the B⁰_s → X(3872)ϕ Decay

Using a data sample of proton-proton collisions at √s = 13  TeV, corresponding to an integrated luminosity of 140  fb⁻¹ collected by the CMS experiment in 2016–2018, the B⁰_s → X(3872)ϕ decay is observed. Decays into J/ψπ⁺π⁻ and K⁺K⁻ are used to reconstruct, respectively, the X(3872) and ϕ. The ratio of the product of branching fractions B[B⁰_s → X(3872)ϕ]B[X(3872) → J/ψπ⁺π−] to the product B[B⁰_s → ψ(2S)ϕ]B[ψ(2S) → J/ψπ⁺π−] is measured to be [2.21±0.29(stat)±0.17(syst)]%. The ratio B[B⁰_s → X(3872)ϕ]/B[B⁰ → X(3872)K⁰] is found to be consistent with one, while the ratio B[B⁰_s → X(3872)ϕ]/B[B⁺ → X(3872)K⁺] is two times smaller. This suggests a difference in the production dynamics of the X(3872) in B⁰ and B⁰_s meson decays compared to B⁺. The reported observation may shed new light on the nature of the X(3872) particle

Search for the lepton flavor violating decay τ → 3μ in proton-proton collisions at s \sqrt{\mathrm{s}} = 13 TeV

Results are reported from a search for the lepton flavor violating decay τ → 3μ in proton-proton collisions at $\sqrt{\mathrm{s}}$ = 13 TeV. The data sample corresponds to an integrated luminosity of 33.2 fb$^{-1}$ recorded by the CMS experiment at the LHC in 2016. The search exploits τ leptons produced in both W boson and heavy-flavor hadron decays. No significant excess above the expected background is observed. An upper limit on the branching fraction B(τ → 3μ) of 8.0 x 10$^{-8}$ at 90% confidence level is obtained, with an expected upper limit of 6.9 x 10$^{-8}$

Observation of Forward Neutron Multiplicity Dependence of Dimuon Acoplanarity in Ultraperipheral Pb-Pb Collisions at sNN\sqrt{sNN} =5.02 TeV

The first measurement of the dependence of γγ→μ$^{+}$ μ$^{-}$ production on the multiplicity of neutrons emitted very close to the beam direction in ultraperipheral heavy ion collisions is reported. Data for lead-lead interactions at $\sqrt{^{s}NN}$=5.02 TeV, with an integrated luminosity of approximately 1.5nb$^{-1}$, are collected using the CMS detector at the LHC. The azimuthal correlations between the two muons in the invariant mass region 88.3. The back-to-back correlation structure from leading-order photon-photon scattering is found to be significantly broader for events with a larger number of emitted neutrons from each nucleus, corresponding to interactions with a smaller impact parameter. This observation provides a data-driven demonstration that the average transverse momentum of photons emitted from relativistic heavy ions has an impact parameter dependence. These results provide new constraints on models of photon-induced interactions in ultraperipheral collisions. They also provide a baseline to search for possible final-state effects on lepton pairs caused by traversing a quark-gluon plasma produced in hadronic heavy ion collisions

Inclusive search for highly boosted Higgs bosons decaying to bottom quark-antiquark pairs in proton-proton collisions at <mml:msqrt>s</mml:msqrt>=13 TeV

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