arXiv subjects

I. Domínguez Jiménez

Publications and source records attributed to I. Domínguez Jiménez.

78 records · Page 5Linked to original sources

arXiv2023

Measurement of the $B^0$ lifetime and flavor-oscillation frequency using hadronic decays reconstructed in 2019-2021 Belle II data

We measure the $B^0$ lifetime and flavor-oscillation frequency using $B^0\to D^{(*)-}π^+$ decays collected by the Belle II experiment in asymmetric-energy $e^+e^-$ collisions produced by the SuperKEKB collider operating at the $Υ(4S)$ resonance. We fit the decay-time distribution of signal decays, where the initial flavor is determined by identifying the flavor of the other $B$ meson in the event. The results, based on $33000$ signal decays reconstructed in a data sample corresponding to ${190}\text{fb}^{-1}$, are $τ_{B^0} = {1.499}\pm{0.013}\pm{0.008}\;\text{ps}$, $Δm_d = {0.516}\pm{0.008}\pm{0.005}\;\text{ps}^{-1}$, where the first uncertainties are statistical and the second are systematic. These results are consistent with the world-average values.

hep-ex↗

arXiv2021

Combined analysis of Belle and Belle II data to determine the CKM angle $ ϕ_{3} $ using $B^+ \to D(K_{S}^0 h^- h^+) h^+$ decays

We present a measurement of the Cabibbo-Kobayashi-Maskawa unitarity triangle angle $ ϕ_{3} $ (also known as~$γ$) using a model-independent Dalitz plot analysis of \linebreak $B^+\to D\left(K_{S}^{0}h^{+}h^{-}\right)h^+$, where $D$ is either a $D^0$ or $\bar{D}{}^0$ meson and $h$ is either a $π$ or $K$. This is the first measurement that simultaneously uses Belle and Belle~II data, combining samples corresponding to integrated luminosities of \SI{711}{fb^{-1}} and \SI{128}{fb^{-1}}, respectively. All data were accumulated from energy-asymmetric $e^+e^-$ collisions at a centre-of-mass energy corresponding to the mass of the $Υ(4S)$ resonance. We measure $ϕ_3 = \left(78.4 \pm 11.4 \pm 0.5 \pm 1.0 \right)^{\circ}$, where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is from the uncertainties on external measurements of the $D$-decay strong-phase parameters.

hep-ex↗

arXiv2021

Precise measurement of the $D^0$ and $D^+$ lifetimes at Belle II

We report a measurement of the $D^0$ and $D^+$ lifetimes using $D^0\to K^-π^+$ and $D^+\to K^-π^+π^+$ decays reconstructed in $e^+e^-\to c\bar{c}$ data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy $e^+e^-$ collider. The data, collected at center-of-mass energies at or near the $Υ(4S)$ resonance, correspond to an integrated luminosity of $72\,{\rm fb}^{-1}$. The results, $τ(D^0) = 410.5\pm1.1\,{\rm(stat)}\pm0.8\,{\rm(syst.)}\,{\rm fs}$ and $τ(D^+) = 1030.4\pm4.7\,{\rm(stat)}\pm3.1\,{\rm(syst.)}\,{\rm fs}$, are the most precise to date and are consistent with previous determinations.

hep-ex↗

arXiv2021

Search for $B^{+}\to K^{+}ν\barν$ decays using an inclusive tagging method at Belle II

A search for the flavor-changing neutral-current decay $B^{+}\to K^{+}ν\barν$ is performed at the Belle II experiment at the SuperKEKB asymmetric energy electron-positron collider. The results are based on a data sample corresponding to an integrated luminosity of $63\,\mbox{fb}^{-1}$ collected at the $Υ{(4S)}$ resonance and a sample of $9\,\mbox{fb}^{-1}$ collected at an energy $60\mathrm{\,Me\kern -0.1em V}$ below the resonance. A novel measurement method is employed, which exploits topological properties of the $B^{+}\to K^{+}ν\barν$ decay that differ from both generic bottom-meson decays and light-quark pair production. This inclusive tagging approach offers a higher signal efficiency compared to previous searches. No significant signal is observed. An upper limit on the branching fraction of $B^{+}\to K^{+}ν\barν$ of $4.1 \times 10^{-5}$ is set at the 90% confidence level.

hep-ex↗

arXiv2020

Search for an invisibly decaying $Z^{\prime}$ boson at Belle II in $e^+ e^- \to μ^+ μ^- (e^{\pm} μ^{\mp})$ plus missing energy final states

Theories beyond the standard model often predict the existence of an additional neutral boson, the $Z^{\prime}$. Using data collected by the Belle II experiment during 2018 at the SuperKEKB collider, we perform the first searches for the invisible decay of a $Z^{\prime}$ in the process $e^+ e^- \to μ^+ μ^- Z^{\prime}$ and of a lepton-flavor-violating $Z^{\prime}$ in $e^+ e^- \to e^{\pm} μ^{\mp} Z^{\prime}$. We do not find any excess of events and set 90\% credibility level upper limits on the cross sections of these processes. We translate the former, in the framework of an $L_μ-L_τ$ theory, into upper limits on the $Z^{\prime}$ coupling constant at the level of $5 \times 10^{-2}$ -- $1$ $M_{Z^\prime}\leq 6$ GeV/$c^2$.

hep-ex↗

arXiv2019

Measurement of the integrated luminosity of the Phase 2 data of the Belle II experiment

From April to July 2018, a data sample at the peak energy of the $Υ(4S)$ resonance was collected with the Belle~II detector at the SuperKEKB electron-positron collider. This is the first data sample of the Belle~II experiment. Using Bhabha and digamma events, we measure the integrated luminosity of the data sample to be ($496.3 \pm 0.3 \pm 3.0$)~pb$^{-1}$, where the first uncertainty is statistical and the second is systematic. This work provides a basis for future luminosity measurements at Belle~II.

hep-ex↗