arXiv subjects

S. A. De La Motte

Publications and source records attributed to S. A. De La Motte.

118 records · Page 7Linked to original sources

arXiv2022

Measurement of decay-time dependent $CP$ violation in $B^0 \rightarrow K^0_S K^0_S K^0_S$ using 2019--2021 Belle II data

We report a measurement of decay-time dependent $CP$-violating parameters in $B^0 \rightarrow K^0_S K^0_S K^0_S$ decays. We use $(198.0 \pm 3.0) \times 10^6\ B\overline{B}$ pairs collected at the $Υ(4S)$ resonance with the Belle II detector at the SuperKEKB asymmetric-energy $e^+e^-$ collider. The observed mixing-induced and direct $CP$ violation parameters are $\mathcal{S} = -1.86\ _{-0.46}^{+0.91}~{\rm (stat)} \pm 0.09~{\rm (syst)}$ and $\mathcal{A} = -0.22\ _{-0.27}^{+0.30}~{\rm (stat)} \pm 0.04~{\rm (syst)}$, respectively.

hep-ex↗

arXiv2022

Study of Exclusive $B \to πe^+ ν_e$ Decays with Hadronic Full-event-interpretation Tagging in 189.3 fb$^{-1}$ of Belle II Data

We present a reconstruction of the semileptonic decays $B^0 \to π^- e^+ ν_e$ and $B^+ \to π^0 e^+ ν_e$ in a sample corresponding to 189.3 fb$^{-1}$ of Belle II data, using events where the partner $B$-meson is reconstructed from a large variety of hadronic channels via a tagging algorithm known as the full-event-interpretation. We determine the partial branching fractions in three bins of the squared momentum transfer to the leptonic system using fits to the distribution of the square of the missing mass. The partial branching fractions are summed to determine $\mathcal{B}(B^0 \to π^- e^+ ν_e)$ = (1.43 $\pm$ 0.27(stat) $\pm$ 0.07(syst)) $\times 10^{-4}$ and $\mathcal{B}(B^+ \to π^0 e^+ ν_e)$ = (8.33 $\pm$ 1.67(stat) $\pm$ 0.55(syst)) $\times 10^{-5}$. We extract a first Belle II measurement of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{\mathrm{ub}}|$, with $|V_{\mathrm{ub}}|$ = (3.88 $\pm$ 0.45) $\times 10^{-3}$.

hep-ex↗

arXiv2022

Measurement of the branching fractions and $CP$ asymmetries of $B^+ \rightarrow π^+ π^0$ and $B^+ \rightarrow K^+ π^0$ decays in 2019-2021 Belle II data

We determine the branching fractions ${\mathcal{B}}$ and $CP$ asymmetries ${\mathcal{A}_{\it CP}}$ of the decays $B^+ \rightarrow π^+ π^0$ and $B^+ \rightarrow K^+ π^0$. The results are based on a data set containing 198 million bottom-antibottom meson pairs corresponding to an integrated luminosity of $190\;\text{fb}^{-1}$ recorded by the Belle II detector in energy-asymmetric electron-positron collisions at the $Υ(4S)$ resonance. We measure ${\mathcal{B}(B^+ \rightarrow π^+ π^0) = (6.12 \pm 0.53 \pm 0.53)\times 10^{-6}}$, ${\mathcal{B}(B^+ \rightarrow K^+ π^0) = (14.30 \pm 0.69 \pm 0.79)\times 10^{-6}}$, ${\mathcal{A}_{\it CP}(B^+ \rightarrow π^+ π^0) = -0.085 \pm 0.085 \pm 0.019}$, and ${\mathcal{A}_{\it CP}(B^+ \rightarrow K^+ π^0) = 0.014 \pm 0.047 \pm 0.010}$, where the first uncertainties are statistical and the second are systematic. These results improve a previous Belle II measurement and agree with the world averages.

hep-ex↗

arXiv2022

Measurement of Branching Fraction and Longitudinal Polarization in $B^0 \to ρ^+ ρ^-$ Decays at Belle II

We present a measurement of the branching fraction and longitudinal polarization of $B^0 \to ρ^+ ρ^-$ decays. SuperKEKB electron-positron collision data corresponding to 189~fb$^{-1}$ of integrated luminosity and containing $198 \times 10^6 B\bar{B}$ pairs collected with the Belle II detector are used. We obtain \begin{eqnarray*} \mathcal{B}(B^0\toρ^+ρ^-) &=& [2.67\pm0.28\,(\mathrm{stat})\,\pm0.28\,(\mathrm{syst})] \times 10^{-5}, \end{eqnarray*} \begin{eqnarray*} f_L &=& 0.956\pm0.035\,(\mathrm{stat})\,\pm 0.033\,(\mathrm{syst}), \end{eqnarray*} These results are consistent with previous measurements and can be used to constrain penguin pollution and to extract the quark-mixing angle $ϕ_2$.

hep-ex↗

arXiv2022

Angular analysis of $B^+ \to ρ^+ρ^0$ decays reconstructed in 2019, 2020, and 2021 Belle II data

We report on a Belle II measurement of the branching fraction ($\mathcal{B}$), longitudinal polarization fraction ($f_L$), and CP asymmetry ($\mathcal{A}_{CP}$) of $B^+\to ρ^+ρ^0$ decays. We reconstruct $B^+\to ρ^+(\to π^+π^0(\to γγ))ρ^0(\to π^+π^-)$ decays in a sample of SuperKEKB electron-positron collisions collected by the Belle II experiment in 2019, 2020, and 2021 at the $Υ$(4S) resonance and corresponding to 190 fb$^{-1}$ of integrated luminosity. We fit the distributions of the difference between expected and observed $B$ candidate energy, continuum-suppression discriminant, dipion masses, and decay angles of the selected samples, to determine a signal yield of $345 \pm 31$ events. The signal yields are corrected for efficiencies determined from simulation and control data samples to obtain $\mathcal{B}(B^+ \to ρ^+ρ^0) = [23.2^{+\ 2.2}_{-\ 2.1} (\rm stat) \pm 2.7 (\rm syst)]\times 10^{-6}$, $f_L = 0.943 ^{+\ 0.035}_{-\ 0.033} (\rm stat)\pm 0.027(\rm syst)$, and $\mathcal{A}_{CP}=-0.069 \pm 0.068(\rm stat) \pm 0.060 (\rm syst)$. The results agree with previous measurements. This is the first measurement of $\mathcal{A}_{CP}$ in $B^+\to ρ^+ρ^0$ decays reported by Belle II.

hep-ex↗

arXiv2022

Measurement of the branching fraction of the $B^0 \to K_S^0 π^0 γ$ decay using 190 fb$^{-1}$ of Belle II data

We report the measurement of the branching fraction of the $B^0 \to K_S^0 π^0 γ$ decay in $e^+ e^- \to Υ(4S) \to B \overline{B}$ data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy collider and corresponding to 190 fb$^{-1}$ of integrated luminosity. The signal yield is measured to be $121\pm 29\,\hbox{(stat.)}$, leading to the branching fraction ${\cal B}\left(B^0 \to K_S^0 π^0 γ\right) = \left(7.3 \pm 1.8\,\hbox{(stat.)} \pm 1.0\,\hbox{(syst.)} \right)\times 10^{-6}$, which agrees with the known value.

hep-ex↗

arXiv2022

Diversity and inclusion activities in Belle II

These proceedings accompany the Belle II talk in the Science in Society parallel session delivered during Lepton Photon 2021. In this talk we present updated membership statistics using 10 years of data with a diversity and inclusion lens, and we present Belle II's most recent activities to aid and improve diversity and inclusion. This report has the intention to bring light to the social working environment and population representation within our collaboration and, by extension, within high energy physics. Belle II is a particle physics collaboration that has over 1000 people from institutions in 26 countries who work together to achieve its physics goals. Belle II is committed to fostering an open, diverse, and inclusive environment; as part of this commitment it created a diversity office to raise awareness of diversity and inclusion issues, promote an inclusive atmosphere within the collaboration, provide a safe and confidential point to contact for collaborators to report any issues, particularly those related to discrimination and harassment, and ensure that persons from underrepresented groups are considered for positions of responsibility within the collaboration. Diversity and inclusion activities and initiatives at Belle II and analysis of the demographics of the collaboration will be presented.

physics.soc-ph↗

arXiv2022

Measurements of $SU(3)_f$ symmetry breaking in $B$ meson decay constants

We present updates from QCDSF/UKQCD/CSSM on the $SU(3)_f$ breaking in $B$ meson decay constants. The $b$-quarks are generated with an anisotropic clover-improved action, and are tuned to match properties of the physical $B$ and $B^*$ mesons. Configurations are generated with $\overline{m}=(1/3)(2m_l+m_s)$ kept constant to control symmetry breaking effects. Various sources of systematic uncertainty will be discussed, including those from continuum extrapolations and extrapolations to the physical point. We also present new efforts to calculate $f_B$ and $f_{B_s}$ using weighted averages across multiple time fitting regions. The use of an automated weighted averaging technique over multiple fitting ranges allows for timely tuning of the $b$-quark and reduces the impact of systematic errors from fitting range biases in calculations of $f_B$ and $f_{B_s}$

hep-lat↗

arXiv2021

Diversity + Inclusion at Belle II: Where We Are, What We've Done and Where We Want To Be

The Belle II Collaboration comprises over 1000 international high energy physicists, who investigate the properties of $b$-quarks and other particles at the luminosity frontier. In order to achieve our aim of a successful physics program, it is essential that we emphasise contributions from a diverse community. Belle II has thus far focused on diversity in gender and sexuality, among other efforts within our collaboration. These efforts are led by our two Diversity Officers, elected to the newly created positions in 2018. Their role has been to promote an inclusive atmosphere, raising awareness of diversity and being a safe first point of call for issues of discrimination and harassment. These proceedings accompany the short talk delivered during ICHEP 2020, marking the first conference the Belle II Collaboration has presented in the diversity and inclusion stream. It details the efforts described above, as well as examining the evolving gender demographics of our community, since membership began in 2011.

physics.ed-ph↗

arXiv2021

Diversity and inclusion activities in Belle II

These proceedings accompany the Belle II talk in the Diversity and Inclusion parallel session delivered during ICHEP 2020. This marks the first external presentation by the Belle II Collaboration, in which we present some of our data and self-reported statistics regarding diversity and inclusion. We also present Belle II's current and planned activities to aid and improve diversity and inclusion. We find that there is still a lot to be done to improve the social working environment and population representation within our collaboration and within high energy physics.

physics.ed-ph↗