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1. Measurement of differential cross sections for Z bosons produced in association with charm jets in pp collisions at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP04(2021)109  

   Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Escalante Del Valle, A.; Frühwirth, R.; Jeitler, M.; Krammer, N.; et al (April 2021, Journal of High Energy Physics)

   null (Ed.)

   A bstract Measurements are presented of differential cross sections for the production of Z bosons in association with at least one jet initiated by a charm quark in pp collisions at $$ \sqrt{s} $$ s = 13 TeV. The data recorded by the CMS experiment at the LHC correspond to an integrated luminosity of 35.9 fb − 1 . The final states contain a pair of electrons or muons that are the decay products of a Z boson, and a jet consistent with being initiated by a charm quark produced in the hard interaction. Differential cross sections as a function of the transverse momentum p T of the Z boson and p T of the charm jet are compared with predictions from Monte Carlo event generators. The inclusive production cross section 405 . 4 ± 5 . 6 (stat) ± 24 . 3 (exp) ± 3 . 7 (theo) pb, is measured in a fiducial region requiring both leptons to have pseudorapidity |η| < 2 . 4 and p T > 10 GeV, at least one lepton with p T > 26 GeV, and a mass of the pair in the range 71–111 GeV, while the charm jet is required to have p T > 30 GeV and |η| < 2 . 4. These are the first measurements of these cross sections in proton-proton collisions at 13 TeV. 

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2. Flavor SU(3) in Cabibbo-favored D-meson decays

   https://doi.org/10.1007/JHEP10(2021)024  

   Bhattacharya, Bhubanjyoti; Datta, Alakabha; Petrov, Alexey A.; Waite, John (October 2021, Journal of High Energy Physics)

   null (Ed.)

   A bstract Model-independent description of nonleptonic decays of charmed mesons is a challenging task due to large nonperturbative effects of strong interactions on the transition amplitudes. We discuss the equivalence of two different flavor-SU(3)-based descriptions of Cabibbo-favored non-leptonic decays of charmed mesons to two-pseudoscalars final states including the η and η ′ mesons. 

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3. Search for new physics in the τ lepton plus missing transverse momentum final state in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP09(2023)051  

   Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Escalante Del Valle, A.; Hussain, P. S.; Jeitler, M.; et al (September 2023, Journal of High Energy Physics)

   A bstract A search for physics beyond the standard model (SM) in the final state with a hadronically decaying tau lepton and a neutrino is presented. This analysis is based on data recorded by the CMS experiment from proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, corresponding to a total integrated luminosity of 138 fb − 1 . The transverse mass spectrum is analyzed for the presence of new physics. No significant deviation from the SM prediction is observed. Limits are set on the production cross section of a W′ boson decaying into a tau lepton and a neutrino. Lower limits are set on the mass of the sequential SM-like heavy charged vector boson and the mass of a quantum black hole. Upper limits are placed on the couplings of a new boson to the SM fermions. Constraints are put on a nonuniversal gauge interaction model and an effective field theory model. For the first time, upper limits on the cross section of t -channel leptoquark (LQ) exchange are presented. These limits are translated into exclusion limits on the LQ mass and on its coupling in the t -channel. The sensitivity of this analysis extends into the parameter space of LQ models that attempt to explain the anomalies observed in B meson decays. The limits presented for the various interpretations are the most stringent to date. Additionally, a model-independent limit is provided. 

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4. Test of lepton universality in beauty-quark decays

   https://doi.org/10.1038/s41567-021-01478-8  

   Aaij, R.; Beteta, C. Abellán; Ackernley, T.; Adeva, B.; Adinolfi, M.; Afsharnia, H.; Aidala, C. A.; Aiola, S.; Ajaltouni, Z.; Akar, S.; et al (March 2022, Nature Physics)

   Abstract The standard model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton–proton collision data collected with the LHCb detector at CERN’s Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the standard model, such as a new fundamental interaction between quarks and leptons. 

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5. Higgs boson decay to charmonia via c-quark fragmentation

   https://doi.org/10.1007/JHEP08(2022)073  

   Han, Tao; Leibovich, Adam K.; Ma, Yang; Tan, Xiao-Ze (August 2022, Journal of High Energy Physics)

   A bstract We calculate the decay branching fractions of the Higgs boson to J / ψ and η c via the charm-quark fragmentation mechanism for the color-singlet and color-octet states in the framework of non-relativistic QCD. The decay rates are governed by the charm-quark Yukawa coupling, unlike the decay H → J / ψ + γ , which is dominated by the γ ∗ - J / ψ mixing. We find that the decay branching fractions can be about 2 × 10 − 5 for $$ H\to c\overline{c}+J/\psi $$ H → c c ¯ + J / ψ , and 6 × 10 − 5 for $$ H\to c\overline{c}+{\eta}_c $$ H → c c ¯ + η c . We comment on the perspective of searching for the Higgs boson to J / ψ transition at the High-Luminosity LHC for testing the charm-quark Yukawa coupling. 

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