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First measurement of coherent photoproduction of Y(1S) mesons in lead-lead ultraperipheral collisions at = 5.02 TeV
No full textCoherent photoproduction of heavy-flavor vector mesons in ultrarelativistic heavy ion collisions (UPCs) provides a direct probe of the gluonic structure of nuclei. This note presents the first measurement of coherent photoproduction of off heavy nuclei. The analysis uses of data collected by the CMS experiment in at the CERN LHC in lead-lead collisions at a center-of-mass energy per nucleon-nucleon pair of . The differential cross section for coherent is presented as a function of rapidity () up to . At photon-nucleus center-of-mass energies per nucleon , the coherent photoproduction cross section is found to be significantly suppressed compared to the expected results from -proton interactions. Results of this study are compared to theoretical calculations based on quantum chromodynamics
Search for resonant double Higgs production in the bbττ final state at the CMS experiment.
No full textThis thesis presents a search for resonant Higgs bosons pair (HH) production via the Gluon-gluon Fusion (ggF) mechanism, predicted in different Beyond Standard Model (BSM) scenarios to be observable with the current Large Hadron Collider (LHC) dataset. The search focuses on the HH → b¯bτ+τ− final state, which offers a good balance between branching fraction and experimental feasibility but presents challenges due to neutrinos in τ decays and background discrimination. Advanced techniques are employed for τ reconstruction and identification, along with sophisticated modeling of the relevant backgrounds. The analysis, performed on proton-proton (pp) collision data collected by the Compact Muon Solenoid (CMS) experiment during Run 2 (2016–2018) with an integrated luminosity of 137.1 fb−1, employs advanced techniques for τ reconstruction and background modeling. The τ+τ− pair is studied through three decay channels: τhτh (fully hadronic) and τhτℓ, where τh represents a tau lepton decaying into hadrons plus a ντ , and τℓ corresponds to the leptonic decay of the tau into either an electron (ℓ = e) or a muon (ℓ = μ). A key aspect of the analysis is the use of machinelearning- based identification algorithms, including DeepTau for τ identification. The primary results are obtained using DeepTau2017v2p1, the stable version recommended for Run 2 analyses. Additionally, a study with DeepTau2018v2p5, an improved and re-trained version optimized for future runs, demonstrates better data/MC agreement, confirming its suitability for upcoming analyses. As part of the CMS internal review process, the analysis remains blinded to avoid bias. The 95% Confidence Level upper limits on the HH production cross section are set as a function of resonance mass and spin, interpreted within the Warped Extra Dimensions theory (WED) model for masses from 250 to 3000 GeV under spin-0 and spin-2 hypotheses
Exact chiral symmetries of Hamiltonian lattice fermions in 3+1d
No full textWe will discuss methods of circumventing the fermion doubling problem in 3+1d Hamiltonian lattice models. In particular, we will construct a 3+1d model with a single Weyl fermion and an exact UV symmetry which implies the conservation of chiral charge in the IR. We will do the same for the SU(2) symmetry of a single Weyl doublet, finding a connection between an object in integrability known as the Onsager algebra, and Witten's SU(2) anomaly. Time permitting, we will also discuss 2+1d models with the parity anomaly.
This talk is based on https://arxiv.org/abs/2503.07708 with Lei Gioia (Caltech)
(online talk)</p
Minutes of 3rd DRD7 Collaboration Board meeting
No full textMinutes of 3rd DRD7 Collaboration Board meeting held on 31st January 202
SMEFT combinations in ATLAS
No full textEFT interpretation in ATLAS, focusing on the role of the EW sector in the combination
