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1. Measurement of off-shell Higgs boson production in the $H^{\ast }\to ZZ\to 4\ell$ decay channel using a neural simulation-based inference technique in 13 TeV pp collisions with the ATLAS detector

   https://doi.org/10.1088/1361-6633/adcd9a  

   The_ATLAS_Collaboration (May 2025, Reports on Progress in Physics)

   Abstract A measurement of off-shell Higgs boson production in the $H^{\ast }\to ZZ\to 4\ell$decay channel is presented. The measurement uses 140 fb⁻¹of proton–proton collisions at $\sqrt{s}=13$TeV collected by the ATLAS detector at the Large Hadron Collider and supersedes the previous result in this decay channel using the same dataset. The data analysis is performed using a neural simulation-based inference method, which builds per-event likelihood ratios using neural networks. The observed (expected) off-shell Higgs boson production signal strength in the $ZZ\to 4\ell$decay channel at 68% CL is ${0.87}_{-0.54}^{+0.75}$( ${1.00}_{-0.95}^{+1.04}$). The evidence for off-shell Higgs boson production using the $ZZ\to 4\ell$decay channel has an observed (expected) significance of 2.5σ(1.3σ). The expected result represents a significant improvement relative to that of the previous analysis of the same dataset, which obtained an expected significance of 0.5σ. When combined with the most recent ATLAS measurement in the $ZZ\to 2\ell 2\nu$decay channel, the evidence for off-shell Higgs boson production has an observed (expected) significance of 3.7σ(2.4σ). The off-shell measurements are combined with the measurement of on-shell Higgs boson production to obtain constraints on the Higgs boson total width. The observed (expected) value of the Higgs boson width at 68% CL is ${4.3}_{-1.9}^{+2.7}$( ${4.1}_{-3.4}^{+3.5}$) MeV. 

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2. Light-flavor particle production in high-multiplicity pp collisions at $$ \sqrt{\textrm{s}} $$ = 13 TeV as a function of transverse spherocity

   https://doi.org/10.1007/JHEP05(2024)184  

   Acharya, S; Adamová, D; Aglieri_Rinella, G; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; Ahuja, I; Akindinov, A; et al (May 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> Results on the transverse spherocity dependence of light-flavor particle production (π, K, p,ϕ, K^*0,$$ {\textrm{K}}_{\textrm{S}}^0 $$ $K_S^0$, Λ, Ξ) at midrapidity in high-multiplicity pp collisions at$$ \sqrt{s} $$ $\sqrt{s}$= 13 TeV were obtained with the ALICE apparatus. The transverse spherocity estimator$$ \left({S}_{\textrm{O}}^{p_{\textrm{T}}=1}\right) $$ $\left(S_O^{p_T=1}\right)$categorizes events by their azimuthal topology. Utilizing narrow selections on$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$ $S_O^{p_T=1}$, it is possible to contrast particle production in collisions dominated by many soft initial interactions with that observed in collisions dominated by one or more hard scatterings. Results are reported for two multiplicity estimators covering different pseudorapidity regions. The$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$ $S_O^{p_T=1}$estimator is found to effectively constrain the hardness of the events when the midrapidity (|η| < 0.8) estimator is used. The production rates of strange particles are found to be slightly higher for soft isotropic topologies, and severely suppressed in hard jet-like topologies. These effects are more pronounced for hadrons with larger mass and strangeness content, and observed when the topological selection is done within a narrow multiplicity interval. This demonstrates that an important aspect of the universal scaling of strangeness enhancement with final-state multiplicity is that high-multiplicity collisions are dominated by soft, isotropic processes. On the contrary, strangeness production in events with jet-like processes is significantly reduced. The results presented in this article are compared with several QCD-inspired Monte Carlo event generators. Models that incorporate a two-component phenomenology, either through mechanisms accounting for string density, or thermal production, are able to describe the observed strangeness enhancement as a function of$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$ $S_O^{p_T=1}$. 

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3. Measurement of the fraction of jet longitudinal momentum carried by ${\mathrm{\Lambda }}_c^{+}$ baryons in $pp$ collisions

   https://doi.org/10.1103/PhysRevD.109.072005  

   Acharya, S; Adamová, D; Adler, A; Aglieri_Rinella, G; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; Ahuja, I; et al (April 2024, Physical Review D)

   Recent measurements of charm-baryon production in hadronic collisions have questioned the universality of charm-quark fragmentation across different collision systems. In this work the fragmentation of charm quarks into charm baryons is probed, by presenting the first measurement of the longitudinal jet momentum fraction carried by ${\mathrm{\Lambda }}_c^{+}$baryons, $z_{\parallel }^{\mathrm{ch}}$, in hadronic collisions. The results are obtained in proton-proton ( $pp$) collisions at $\sqrt{s}=13\mathrm{TeV}$at the LHC, with ${\mathrm{\Lambda }}_c^{+}$baryons and charged (track-based) jets reconstructed in the transverse momentum intervals of $3\le p_T^{{\mathrm{\Lambda }}_c^{+}}<15\mathrm{GeV}/c$and $7\le p_T^{\text{jet ch}}<15\mathrm{GeV}/c$, respectively. The $z_{\parallel }^{\mathrm{ch}}$distribution is compared to a measurement of ${\mathrm{D}}^0$-tagged charged jets in $pp$collisions as well as to 8 simulations. The data hints that the fragmentation of charm quarks into charm baryons is softer with respect to charm mesons, in the measured kinematic interval, as predicted by hadronization models which include color correlations beyond leading-color in the string formation. © 2024 CERN, for the ALICE Collaboration2024CERN 

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4. First Double-Differential Cross Section Measurement of Neutral-Current ${\pi }^0$ Production in Neutrino-Argon Scattering in the MicroBooNE Detector

   https://doi.org/10.1103/PhysRevLett.134.161802  

   Abratenko, P; Alterkait, O; Andrade_Aldana, D; Arellano, L; Asaadi, J; Ashkenazi, A; Balasubramanian, S; Baller, B; Barnard, A; Barr, G; et al (April 2025, Physical Review Letters)

   We report the first double-differential cross section measurement of neutral-current neutral pion ( $\mathrm{NC}{\pi }^0$) production in neutrino-argon scattering, as well as single-differential measurements of the same channel in terms of final states with and without protons. The kinematic variables of interest for these measurements are the ${\pi }^0$momentum and the ${\pi }^0$scattering angle with respect to the neutrino beam. A total of 4971 candidate $\mathrm{NC}{\pi }^0$events fully contained within the MicroBooNE detector are selected using data collected at a mean neutrino energy of $\sim 0.8\mathrm{GeV}$from $6.4\times {10}^{20}$protons on target from the Booster Neutrino Beam at the Fermi National Accelerator Laboratory. After extensive data-driven model validation to ensure unbiased unfolding, the Wiener-singular-value-decomposition method is used to extract nominal flux-averaged cross sections. The results are compared to predictions from commonly used neutrino event generators, which tend to overpredict the measured $\mathrm{NC}{\pi }^0$cross section, especially in the $0.2–0.5\mathrm{GeV}/\mathrm{c}$ ${\pi }^0$momentum range and at forward scattering angles. Events with at least one proton present in the final state are also underestimated. This data will help improve the modeling of $\mathrm{NC}{\pi }^0$production, which represents a major background in measurements of charge-parity violation in the neutrino sector and in searches for new physics beyond the standard model. 

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5. Measurement of $WWZ$ and $ZH$ Production Cross Sections at $\sqrt{s}=13$ and 13.6 TeV

   https://doi.org/10.1103/6z3d-zjw4  

   Hayrapetyan, A; Makarenko, V; Tumasyan, A; Adam, W; Andrejkovic, J W; Benato, L; Bergauer, T; Damanakis, K; Dragicevic, M; Giordano, C; et al (August 2025, Physical Review Letters)

   A measurement is presented of the cross section in proton-proton collisions for the production of two $W$bosons and one $Z$boson. It is based on data recorded by the CMS experiment at the CERN LHC at center-of-mass energies $\sqrt{s}=13$and 13.6 TeV, corresponding to an integrated luminosity of $200{\mathrm{fb}}^{-1}$. Events with four charged leptons (electrons or muons) in the final state are selected. Both nonresonant $WWZ$production and $ZH$production, with the Higgs boson decaying into two $W$bosons, are reported. For the first time, the two processes are measured separately in a simultaneous fit. Combining the two modes, signal strengths relative to the standard model (SM) predictions of ${0.75}_{-0.29}^{+0.34}$and ${1.74}_{-0.60}^{+0.71}$are measured for $\sqrt{s}=13$and 13.6 TeV, respectively. The observed (expected) significance for the triboson signal is 3.8 (2.5) standard deviations for $\sqrt{s}=13.6\mathrm{TeV}$, thus providing the first evidence for triboson production at this center-of-mass energy. Combining the two modes and the two center-of-mass energies, the inclusive signal strength relative to the SM prediction is measured to be ${1.03}_{-0.28}^{+0.31}$, with an observed (expected) significance of 4.5 (5.0) standard deviations. 

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