A search is presented for fractionally charged particles with charges below 1e, using their small energy loss in the tracking detector as a key variable to observe a signal. The analyzed dataset corresponds to an integrated luminosity of 138 fb^{-1} of proton-proton collisions collected at sqrt[s]=13 TeV in 2016-2018 at the CERN LHC. This is the first search at the LHC for new particles with a charge between e/3 and 0.9e, including an extension of previous results at a charge of 2e/3. Masses up to 640 GeV and charges as low as e/3 are excluded at 95% confidence level. These are the most stringent limits to date for the considered Drell-Yan-like production mode.
- Publikační typ
- časopisecké články MeSH
Nuclear medium effects on B^{+} meson production are studied using the binary-collision scaled cross section ratio between events of different charged-particle multiplicities from proton-lead collisions. Data, collected by the CMS experiment in 2016 at a nucleon-nucleon center-of-mass energy of sqrt[s_{NN}]=8.16 TeV, corresponding to an integrated luminosity of 175 nb^{-1}, were used. The scaling factors in the ratio are determined using a novel approach based on the Z→μ^{-}μ^{+} cross sections measured in the same events. The scaled ratio for B^{+} is consistent with unity for all event multiplicities, putting stringent constraints on nuclear modification for heavy flavor.
- Publikační typ
- časopisecké články MeSH
A search is presented for an extended Higgs sector with two new particles, X and ϕ, in the process X→ϕϕ→(γγ)(γγ). Novel neural networks classify events with diphotons that are merged and determine the diphoton masses. The search uses LHC proton-proton collision data at sqrt[s]=13 TeV collected with the CMS detector, corresponding to an integrated luminosity of 138 fb^{-1}. No evidence of such resonances is seen. Upper limits are set on the production cross section for m_{X} between 300 and 3000 GeV and m_{ϕ}/m_{X} between 0.5% and 2.5%, representing the most sensitive search in this channel.
- Publikační typ
- časopisecké články MeSH
The effects of deficiency of cryptochrome 1 (CRY1), phytochrome B2 (phyB2) and the photoreceptor signalling DET-1 protein (hp-2 mutant) on photosynthesis and pro-/antioxidant balance in Solanum lycopersicum exposed to high-intensity blue light [HIBL, 72 h, 500/1,000 μmol(photon) m-2 s-1] were studied. Noticeable photoinhibition of photosynthesis and PSII was found in all these variants. However, the greatest decrease in photosynthesis and PSII activity was observed in the cry1 mutant. The difference among the other options was less pronounced. This low resistance of the cry1 mutant to HIBL is associated with reduced photosynthetic pigments, phenols, and anthocyanins. It appears that under HIBL, CRY1 and, to a lesser extent, phyB2 are required to maintain photosynthesis and antioxidant defence, mitigating blue light-induced oxidative stress. This study expands our understanding of the defence functions of CRY1 and highlights its importance in adapting the photosynthetic apparatus to HIBL.
- Klíčová slova
- Chl a fluorescence, blue irradiation, high irradiance, photoinhibition, photosynthetic activity, tomato,
- MeSH
- antioxidancia metabolismus MeSH
- fotosyntéza * účinky záření fyziologie MeSH
- fotosystém II (proteinový komplex) metabolismus MeSH
- kryptochromy * metabolismus genetika MeSH
- modré světlo MeSH
- mutace MeSH
- rostlinné proteiny * metabolismus genetika MeSH
- Solanum lycopersicum * účinky záření metabolismus fyziologie genetika MeSH
- světlo * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- antioxidancia MeSH
- fotosystém II (proteinový komplex) MeSH
- kryptochromy * MeSH
- rostlinné proteiny * MeSH
Searches for pair-produced multijet signatures using data corresponding to an integrated luminosity of 128 fb^{-1} of proton-proton collisions at sqrt[s]=13 TeV are presented. A data scouting technique is employed to record events with low jet scalar transverse momentum sum values. The electroweak production of particles predicted in R-parity violating supersymmetric models is probed for the first time with fully hadronic final states. This is the first search for prompt hadronically decaying mass-degenerate higgsinos, and extends current exclusions on R-parity violating top squarks and gluinos.
- Publikační typ
- časopisecké články MeSH
The first search for soft unclustered energy patterns (SUEPs) is performed using an integrated luminosity of 138 fb^{-1} of proton-proton collision data at sqrt[s]=13 TeV, collected in 2016-2018 by the CMS detector at the LHC. Such SUEPs are predicted by hidden valley models with a new, confining force with a large 't Hooft coupling. In events with boosted topologies, selected by high-threshold hadronic triggers, the multiplicity and sphericity of clustered tracks are used to reject the background from standard model quantum chromodynamics. With no observed excess of events over the standard model expectation, limits are set on the cross section for production via gluon fusion of a scalar mediator with SUEP-like decays.
- Publikační typ
- časopisecké články MeSH
The first search for the Z boson decay to ττμμ at the CERN LHC is presented, based on data collected by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb^{-1}. The data are compatible with the predicted background. For the first time, an upper limit at the 95% confidence level of 6.9 times the standard model expectation is placed on the ratio of the Z→ττμμ to Z→4μ branching fractions. Limits are also placed on the six flavor-conserving four-lepton effective-field-theory operators involving two muons and two tau leptons, for the first time testing all such operators.
- Publikační typ
- časopisecké články MeSH
Using proton-proton collision data corresponding to an integrated luminosity of 140 fb - 1 collected by the CMS experiment at s = 13 Te V , the Λ b 0 → J / ψ Ξ - K + decay is observed for the first time, with a statistical significance exceeding 5 standard deviations. The relative branching fraction, with respect to the Λ b 0 → ψ ( 2 S ) Λ decay, is measured to be B ( Λ b 0 → J / ψ Ξ - K + ) / B ( Λ b 0 → ψ ( 2 S ) Λ ) = [ 3.38 ± 1.02 ± 0.61 ± 0.03 ] % , where the first uncertainty is statistical, the second is systematic, and the third is related to the uncertainties in B ( ψ ( 2 S ) → J / ψ π + π - ) and B ( Ξ - → Λ π - ) .
- Publikační typ
- časopisecké články MeSH
A search for collective effects inside jets produced in proton-proton collisions is performed via correlation measurements of charged particles using the CMS detector at the CERN LHC. The analysis uses data collected at a center-of-mass energy of sqrt[s]=13 TeV, corresponding to an integrated luminosity of 138 fb^{-1}. Jets are reconstructed with the anti-k_{T} algorithm with a distance parameter of 0.8 and are required to have transverse momentum greater than 550 GeV and pseudorapidity |η^{jet}|<1.6. Two-particle correlations among the charged particles within the jets are studied as functions of the particles' azimuthal angle and pseudorapidity separations (Δϕ^{*} and Δη^{*}) in a jet coordinate basis, where particles' η^{*}, ϕ^{*} are defined relative to the direction of the jet. The correlation functions are studied in classes of in-jet charged-particle multiplicity up to N_{ch}^{j}≈100. Fourier harmonics are extracted from long-range azimuthal correlation functions to characterize azimuthal anisotropy for |Δη^{*}|>2. For low-N_{ch}^{j} jets, the long-range elliptic anisotropic harmonic, v_{2}^{*}, is observed to decrease with N_{ch}^{j}. This trend is well described by Monte Carlo event generators. However, a rising trend for v_{2}^{*} emerges at N_{ch}^{j}≳80, hinting at a possible onset of collective behavior, which is not reproduced by the models tested. This observation yields new insights into the dynamics of jet evolution in the vacuum.
- Publikační typ
- časopisecké články MeSH
New results are presented on a high-statistics measurement of Collins and Sivers asymmetries of charged hadrons produced in deep inelastic scattering of muons on a transversely polarized ^{6}LiD target. The data were taken in 2022 with the COMPASS spectrometer using the 160 GeV muon beam at CERN, statistically balancing the existing data on transversely polarized proton targets. The first results from about two-thirds of the new data have total uncertainties smaller by up to a factor of three compared to the previous deuteron measurements. Using all the COMPASS proton and deuteron results, both the transversity and the Sivers distribution functions of the u and d quark, as well as the tensor charge in the measured x range are extracted. In particular, the accuracy of the d quark results is significantly improved.
- Publikační typ
- časopisecké články MeSH
