More Like this

1. Measurement of the branching fraction of the decay $B^{-}\to D^0\rho (770{)}^{-}$ at Belle II

   https://doi.org/10.1103/PhysRevD.109.L111103  

   Adachi, I; Aggarwal, L; Aihara, H; Akopov, N; Aloisio, A; Anh_Ky, N; Asner, D M; Atmacan, H; Aushev, V; Aversano, M; et al (June 2024, Physical Review D)

   We measure the branching fraction of the decay $B^{-}\to D^0\rho (770{)}^{-}$using data collected with the Belle II detector. The data contain 387 million $B\overline{B}$pairs produced in $e^{+}{e}^{-}$collisions at the $\mathrm{\Upsilon }\left(4S\right)$resonance. We reconstruct $8360\pm 180$decays from an analysis of the distributions of the $B^{-}$energy and the $\rho (770{)}^{-}$helicity angle. We determine the branching fraction to be $(0.939\pm 0.021\left(\mathrm{stat}\right)\pm 0.050\left(\mathrm{syst}\right))\%$, in agreement with previous results. Our measurement improves the relative precision of the world average by more than a factor of two. Published by the American Physical Society2024 

   more » « less
2. $\omega$ Meson from Lattice QCD

   https://doi.org/10.1103/PhysRevLett.133.211906  

   Yan, Haobo; Mai, Maxim; Garofalo, Marco; Meißner, Ulf-G; Liu, Chuan; Liu, Liuming; Urbach, Carsten (November 2024, Physical Review Letters)

   Many excited states in the hadron spectrum have large branching ratios to three-hadron final states. Understanding such particles from first principles QCD requires input from lattice QCD with one-, two-, and three-meson interpolators as well as a reliable three-body formalism relating finite-volume spectra at unphysical pion mass values to the scattering amplitudes at the physical point. In this work, we provide the first-ever calculation of the resonance parameters of the $\omega$meson from lattice QCD, including an update of the formalism through matching to effective field theories. The main result of this pioneering study, the pole position of the $\omega$meson at $\sqrt{s_{\omega }}=\left(778.0\right(11.2)-i3.0(5\left)\right)\mathrm{MeV}$, agrees reasonably well with experiment. In addition we provide an estimate of the $\omega -\rho$mass difference as 29(15) MeV. Published by the American Physical Society2024 

   more » « less
3. Instantons in ${\varphi }^4$ theories: Transseries, virial theorems, and numerical aspects

   https://doi.org/10.1103/PhysRevD.110.036003  

   Giorgini, Ludovico T; Jentschura, Ulrich D; Malatesta, Enrico M; Rizzo, Tommaso; Zinn-Justin, Jean (August 2024, Physical Review D)

   We discuss numerical aspects of instantons in two- and three-dimensional ${\varphi }^4$theories with an internal $O\left(N\right)$symmetry group, the so-called $N$-vector model. By combining asymptotic transseries expansions for large arguments with convergence acceleration techniques, we obtain high-precision values for certain integrals of the instanton that naturally occur in loop corrections around instanton configurations. Knowledge of these numerical properties is necessary in order to evaluate corrections to the large-order factorial growth of perturbation theory in ${\varphi }^4$theories. The results contribute to the understanding of the mathematical structures underlying the instanton configurations. Published by the American Physical Society2024 

   more » « less
4. 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 

   more » « less
5. New graph-neural-network flavor tagger for Belle II and measurement of sin $2{\varphi }_1$ in $B^0\to J/\psi K_{\mathrm{S}}^0$ decays

   https://doi.org/10.1103/PhysRevD.110.012001  

   Adachi, I; Aggarwal, L; Ahmed, H; Aihara, H; Akopov, N; Aloisio, A; Anh_Ky, N; Asner, D M; Atmacan, H; Aushev, T; et al (July 2024, Physical Review D)

   We present GFlaT, a new algorithm that uses a graph-neural-network to determine the flavor of neutral $B$mesons produced in $\mathrm{\Upsilon }\left(4S\right)$decays. It improves previous algorithms by using the information from all charged final-state particles and the relations between them. We evaluate its performance using $B$decays to flavor-specific hadronic final states reconstructed in a $362{\mathrm{fb}}^{-1}$sample of electron-positron collisions collected at the $\mathrm{\Upsilon }\left(4S\right)$resonance with the Belle II detector at the SuperKEKB collider. We achieve an effective tagging efficiency of $(37.40\pm 0.43\pm 0.36\%)$, where the first uncertainty is statistical and the second systematic, which is 18% better than the previous Belle II algorithm. Demonstrating the algorithm, we use $B^0\to J/\psi K_{\mathrm{S}}^0$decays to measure the mixing-induced and direct $CP$violation parameters, $S=(0.724\pm 0.035\pm 0.009)$and $C=(-0.035\pm 0.026\pm 0.029)$. Published by the American Physical Society2024 

   more » « less