129 Search Results

The first measurements of the Fourier coefficients ( $V_{n\mathrm{\Delta }}$ ) of the azimuthal distributions of charged hadrons emitted from photon-proton (γp) interactions are presented. The data are extracted from 68.8 nb⁻¹ of ultra-peripheral proton-lead (pPb) collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=8.16\text{TeV}$ using the CMS detector. The high energy lead ions produce a flux of photons that can interact with the oncoming proton. This γp system provides a set of uniquemore » initial conditions with multiplicity lower than in photon-lead collisions but comparable to recent electron-positron and electron-proton data. The $V_{n\mathrm{\Delta }}$ coefficients are presented in ranges of event multiplicity and transverse momentum ( $p_{\mathrm{T}}$ ) and are compared to corresponding hadronic minimum bias pPb results. For a given multiplicity range, the mean $p_{\mathrm{T}}$ of charged particles is smaller in γp than in pPb collisions. For both the γp and pPb samples, $V_{1\mathrm{\Delta }}$ is negative, $V_{2\mathrm{\Delta }}$ is positive, and $V_{3\mathrm{\Delta }}$ consistent with 0. For each multiplicity and $p_{\mathrm{T}}$ range, $V_{2\mathrm{\Delta }}$ is larger for γp events. The γp data are consistent with model predictions that have no collective effects.« less

A search for the exotic decay of the Higgs boson to a pair of light pseudoscalars, each of which subsequently decays into a pair of photons, is presented. The search uses data from proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV recorded with the CMS detector at the LHC that corresponds to an integrated luminosity of 132 fb$$^{−1}$$. The analysis probes pseudoscalar bosons with masses in the range 15–62 GeV, coming from the Higgs boson decay, which leads to four well-isolated photons in the final state. No significant deviation from the background-only hypothesis is observed. Upper limits are setmore » on the product of the Higgs boson production cross section and branching fraction into four photons. The observed (expected) limits range from 0.80 (1.00) fb for a pseudoscalar boson mass of 15 GeV to 0.26 (0.24) fb for a mass of 62 GeV at 95% confidence level.[graphic not available: see fulltext]« less

A search for the direct production of a pair of $$τ$$ sleptons, the supersymmetric partners of $$τ$$ leptons, is presented. Each $$τ$$ slepton is assumed to decay to a $$τ$$ lepton and the lightest supersymmetric particle (LSP), which is assumed to be stable and to not interact in the detector, leading to an imbalance in the total reconstructed transverse momentum. The search is carried out in events identified as containing two $$τ$$ leptons, each decaying to one or more hadrons and a neutrino, and significant transverse momentum imbalance. In addition to scenarios in which the $$τ$$ sleptons decay promptly, themore » search also addresses scenarios in which the $$τ$$ sleptons have sufficiently long lifetimes to give rise to nonprompt $$τ$$ leptons. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC with the CMS detector in 2016–2018, and correspond to an integrated luminosity of 138 fb^-1. No significant excess is seen with respect to standard model expectations. Upper limits on cross sections for the pair production of $$τ$$ sleptons are obtained in the framework of simplified models. In a scenario in which the $$τ$$ sleptons are superpartners of left-handed $$τ$$ leptons, and each undergoes a prompt decay to a $$τ$$ lepton and a nearly massless LSP, $$τ$$ slepton masses between 115 and 340 GeV are excluded. In a scenario in which the lifetime of the $$τ$$ sleptons corresponds to c$$τ$$₀ = 0.1 mm, where $$τ_{0}$$ represents the mean proper lifetime of the $$τ$$ slepton, masses between 150 and 220 GeV are excluded.« less

The double differential cross sections of the Drell–Yan lepton pair ($$\ell^+\ell^-$$, dielectron or dimuon) production are measured as functions of the invariant mass m$$_{\ell\ell}$$, transverse momentum p_T($$\ell\ell$$), and $$\varphi^{*}_{\eta}$$. The observable, derived from angular measurements of the leptons and highly correlated with p_T($$\ell\ell$$), is used to probe the low-p_T region in a complementary way. Dilepton masses up to 1 TeV are investigated. Additionally, a measurement is performed requiring at least one jet in the final state. To benefit from partial cancellation of the systematic uncertainty, the ratios of the differential cross sections for various m$$_{\ell\ell}$$ ranges to those in themore » Z mass peak interval are presented. The collected data correspond to an integrated luminosity of 36.3 fb^-1 of proton–proton collisions recorded with the CMS detector at the LHC at a centre-of-mass energy of 13 TeV. Measurements are compared with predictions based on perturbative quantum chromodynamics, including soft-gluon resummation.« less