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1. Measurement of Angular Coefficients of $\overline{B}\to D^{*}\ell {\overline{\nu }}_{\ell }$ : Implications for $\left|V_{cb}\right|$ and Tests of Lepton Flavor Universality

   https://doi.org/10.1103/PhysRevLett.133.131801  

   Prim, M T; Bernlochner, F; Metzner, F; Aihara, H; Asner, D M; Aushev, T; Ayad, R; Babu, V; Banerjee, Sw; Behera, P; et al (September 2024, Physical Review Letters)

   We measure the complete set of angular coefficients $J_i$for exclusive $\overline{B}\to D^{*}\ell {\overline{\nu }}_{\ell }$decays ( $\ell =e$, $\mu$). Our analysis uses the full $711{\mathrm{fb}}^{-1}$Belle dataset with hadronic tag-side reconstruction. The results allow us to extract the form factors describing the $\overline{B}\to D^{*}$transition and the Cabibbo-Kobayashi-Maskawa matrix element $\left|V_{\mathrm{cb}}\right|$. Using recent lattice QCD calculations for the hadronic form factors, we find $\left|V_{\mathrm{cb}}\right|=(40.7\pm 0.7)\times {10}^{-3}$using the Boyd-Grinstein-Lebed parametrization, compatible with determinations from inclusive semileptonic decays. We search for lepton flavor universality violation as a function of the hadronic recoil parameter $w$and investigate the differences of the electron and muon angular distributions. We find no deviation from standard model expectations. Published by the American Physical Society2024 

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2. Detailed report on the measurement of the positive muon anomalous magnetic moment to 0.20 ppm

   https://doi.org/10.1103/PhysRevD.110.032009  

   Aguillard, D P; Albahri, T; Allspach, D; Anisenkov, A; Badgley, K; Baeßler, S; Bailey, I; Bailey, L; Baranov, V A; Barlas-Yucel, E; et al (August 2024, Physical Review D)

   We present details on a new measurement of the muon magnetic anomaly, $a_{\mu }=(g_{\mu }-2)/2$. The result is based on positive muon data taken at Fermilab’s Muon Campus during the 2019 and 2020 accelerator runs. The measurement uses $3.1\mathrm{GeV}/c$polarized muons stored in a 7.1-m-radius storage ring with a 1.45 T uniform magnetic field. The value of $a_{\mu }$is determined from the measured difference between the muon spin precession frequency and its cyclotron frequency. This difference is normalized to the strength of the magnetic field, measured using nuclear magnetic resonance. The ratio is then corrected for small contributions from beam motion, beam dispersion, and transient magnetic fields. We measure $a_{\mu }=116592057\left(25\right)\times {10}^{-11}$(0.21 ppm). This is the world’s most precise measurement of this quantity and represents a factor of 2.2 improvement over our previous result based on the 2018 dataset. In combination, the two datasets yield $a_{\mu }\left(\mathrm{FNAL}\right)=116592055\left(24\right)\times {10}^{-11}$(0.20 ppm). Combining this with the measurements from Brookhaven National Laboratory for both positive and negative muons, the new world average is $a_{\mu }\left(\exp \right)=116592059\left(22\right)\times {10}^{-11}$(0.19 ppm). Published by the American Physical Society2024 

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3. Enhanced muonization by active-sterile neutrino mixing in protoneutron stars

   https://doi.org/10.1103/PhysRevD.110.043007  

   Ray, Anupam; Qian, Yong-Zhong (August 2024, Physical Review D)

   We study ${\nu }_{\mu }\text{−}{\nu }_s$and ${\overline{\nu }}_{\mu }\text{−}{\overline{\nu }}_s$mixing in the protoneutron star (PNS) created in a core-collapse supernova (CCSN). We point out the importance of the feedback on the general composition of the PNS in addition to the obvious feedback on the ${\nu }_{\mu }$lepton number. We show that for our adopted mixing parameters $\delta m^2\sim {10}^2{\mathrm{keV}}^2$and ${\sin }^{2}2\theta$consistent with the current constraints, sterile neutrino production is dominated by the Mikheyev–Smirnov–Wolfenstein conversion of ${\overline{\nu }}_{\mu }$into ${\overline{\nu }}_s$and that the subsequent escape of ${\overline{\nu }}_s$increases the ${\nu }_{\mu }$lepton number, which in turn enhances muonization of the PNS primarily through ${\nu }_{\mu }+n\to p+{\mu }^{-}$. While these results are qualitatively robust, their quantitative effects on the dynamics and active neutrino emission of core-collapse supernovae should be evaluated by including ${\nu }_{\mu }\text{−}{\nu }_s$and ${\overline{\nu }}_{\mu }\text{−}{\overline{\nu }}_s$mixing in the simulations. Published by the American Physical Society2024 

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4. Search for charged-lepton flavor violation in the production and decay of top quarks using trilepton final states in proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$

   https://doi.org/10.1103/PhysRevD.111.012009  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Escalante_Del_Valle, A; Hussain, P S; et al (January 2025, Physical Review D)

   A search is performed for charged-lepton flavor violating processes in top quark ( $t$) production and decay. The data were collected by the CMS experiment from proton-proton collisions at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of $138{\mathrm{fb}}^{-1}$. The selected events are required to contain one opposite-sign electron-muon pair, a third charged lepton (electron or muon), and at least one jet of which no more than one is associated with a bottom quark. Boosted decision trees are used to distinguish signal from background, exploiting differences in the kinematics of the final states particles. The data are consistent with the standard model expectation. Upper limits at 95% confidence level are placed in the context of effective field theory on the Wilson coefficients, which range between $0.024–0.424{\mathrm{TeV}}^{-2}$depending on the flavor of the associated light quark and the Lorentz structure of the interaction. These limits are converted to upper limits on branching fractions involving up (charm) quarks, $t\to e\mu u$( $t\to e\mu c$), of $0.032\left(0.498\right)\times {10}^{-6}$, $0.022\left(0.369\right)\times {10}^{-6}$, and $0.012\left(0.216\right)\times {10}^{-6}$for tensorlike, vectorlike, and scalarlike interactions, respectively. 

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5. Measurement of the branching fraction and $CP$ -violating asymmetry of the decay $B^0\to {\pi }^0{\pi }^0$ using 387 million $\mathrm{\Upsilon }\left(4S\right)$ decays in Belle II data

   https://doi.org/10.1103/PhysRevD.111.L071102  

   Adachi, I; Aggarwal, L; Ahmed, H; Aihara, H; Alhakami, M; Aloisio, A; Althubiti, N; Anh_Ky, N; Asner, D M; Atmacan, H; et al (April 2025, Physical Review D)

   We measure the branching fraction and $CP$-violating flavor-dependent rate asymmetry of $B^0\to {\pi }^0{\pi }^0$decays reconstructed using the Belle II detector in an electron-positron collision sample containing $387\times {10}^6\mathrm{\Upsilon }\left(4S\right)$mesons. Using an optimized event selection, we find $125\pm 20$signal decays in a fit to background-discriminating and flavor-sensitive distributions. The resulting branching fraction is $(1.25\pm 0.23)\times {10}^{-6}$and the $CP$-violating asymmetry is $0.03\pm 0.30$. Published by the American Physical Society2025 

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