arXiv subjects

P. K. Resmi

Publications and source records attributed to P. K. Resmi.

6 recordsLinked to original sources

arXiv2019

First measurements of the $ϕ_3$-sensitive decay $B^{\pm} \to D(K_{\rm S}^0 π^+ π^- π^0) K^{\pm}$ with Belle

The current experimental uncertainty on the CKM unitarity triangle angle $ϕ_3$ is significantly larger than that on the standard model prediction. A more precise measurement of $ϕ_3$ is crucial for testing the SM description of $CP$ violation and probing for new physics effects. The precision can be improved by exploring new $B$ and $D$ decay modes. The first model-independent measurement of the CKM angle $ϕ_3$ using $B^{\pm} \to D(K_{\rm S}^0 π^+ π^- π^0) K^{\pm}$ decays is presented here. The GGSZ method is used by binning the five-dimensional phase space of the $D$ decay. This analysis uses the measurement of the average strong-phase differences across the phase space in $D\to K_{\rm S}^0 π^+ π^- π^0$ decays from CLEO-c, as input. The results are obtained from the full Belle data set with an integrated luminosity of 711~fb$^{-1}$ collected at the $Υ(4S)$ resonance.

hep-ex↗

arXiv2019

First measurement of the CKM angle $ϕ_3$ with $B^{\pm}\to D(K_{\rm S}^0π^+π^-π^0)K^{\pm}$ decays

We present the first model-independent measurement of the CKM unitarity triangle angle $ϕ_3$ using $B^{\pm}\to D(K_{\rm S}^0π^+π^-π^0)K^{\pm}$ decays, where $D$ indicates either a $D^{0}$ or $\overline{D}^{0}$ meson. Measurements of the strong-phase difference of the $D \to K_{\rm S}^0π^+π^-π^0$ amplitude obtained from CLEO-c data are used as input. This analysis is based on the full Belle data set of $772\times 10^{6}$ $B\overline{B}$ events collected at the $Υ(4S)$ resonance. We obtain $ϕ_3 = (5.7~^{+10.2}_{-8.8} \pm 3.5 \pm 5.7)^{\circ}$ and the suppressed amplitude ratio $r_{B} = 0.323 \pm 0.147 \pm 0.023 \pm 0.051$. Here the first uncertainty is statistical, the second is the experimental systematic, and the third is due to the precision of the strong-phase parameters measured from CLEO-c data. The 95% confidence interval on $ϕ_3$ is $(-29.7,~109.5)^{\circ}$, which is consistent with the current world average.

hep-ex↗

arXiv2019

Measurement of the CKM angle $ϕ_3$ at Belle II

The precise measurement of the CKM angle $ϕ_3$ is important to further test the Standard Model description of $CP$ violation. The small values of the branching fractions of the decays involved in the measurement limits the precision, hence a larger dataset has to be accumulated to improve the precision. The Belle~II experiment at the SuperKEKB asymmetric-energy $e^+e^-$ collider aims to collect 50~ab$^{-1}$ of data, a factor of 50 more than that of its predecessor Belle. The accelerator has been successfully commissioned in 2016 and the first physics collisions were recorded in April 2018. The best sensitivity to $ϕ_3$ can be achieved by harnessing all possible final states of $B \to D^{(*)}K^{(*)}$ decays. With the full dataset, Belle~II is expected to achieve a precision of 1$^{\circ}$ for the angle $ϕ_3$. The expected sensitivities and rediscoveries from 2018 data are presented here.

hep-ex↗

arXiv2019

Construction and quality assurance of the Belle II Silicon Vertex Detector

The Belle II experiment, which is situated at the interaction point of the SuperKEKB $e^+e^{-}$ collider at KEK, Tsukuba, Japan, is expected to collect data corresponding to an integrated luminosity of 50~ab$^{- 1}$. This data set will be sensitive to beyond-the-standard-model physics via precision measurements and searches for very rare decays. At its heart lies a six-layer vertex detector consisting of two layers of pixel detectors (PXD) and four layers of double-sided silicon microstrip detectors (SVD). Precise vertexing as provided by this device is essential for measurements of time-dependent $CP$ violation. Crucial aspects of the SVD assembly are precise alignment, as well as rigorous electrical and geometrical quality assurance. We present an overview of the construction of the SVD, including the precision gluing of SVD component modules and the wire-bonding of various electrical components. We also discuss the electrical and geometrical quality assurance tests.

physics.ins-det↗

arXiv2018

Latest results on $B\to DK/Dπ$ decays from Belle

The CKM angle $ϕ_3$ is less precisely known than the angle $ϕ_1$ and the only one that is accessible with tree-level decays in a theoretically clean way. The key method to measure $ϕ_3$ is through the interference between $B^+\to D^0 K^+$ and $B^+ \to \bar D^0 K^+$ decays which occurs if the final state of the charm-meson decay is accessible to both the $D^0$ and $\bar D^0$ mesons. To achieve the best sensitivity, a large variety of $D$ and $B$ decay modes is required, which is possible at Belle experiment as almost any final state can be reconstructed including those with photons. The results from Belle, as well as the ongoing studies, are discussed here. The details of the planned measurement at Belle II, a substantial upgrade of the Belle detector which will operate at the SuperKEKB energy-asymmetric $e^+ e^-$ collider, are also discussed. The results from the first collisions at Belle II during April-July 2018 are shown too.

hep-ex↗

arXiv2018

Input from the charm threshold for the measurement of $γ$

A brief overview of the inputs from charm threshold that are essential to the determination of the Unitarity Triangle angle $γ$ is presented. The focus is on the measurements of four-body final states that have not previously been considered: $D^0\to K_{\rm S}^0 π^+ π^- π^0 $ and $D^0 \to π^+ π^- π^+ π^-$.

hep-ex↗