arXiv subjects

Bilas Pal

Publications and source records attributed to Bilas Pal.

10 recordsLinked to original sources

arXiv2025

The Imaging Time-of-Propagation Detector at Belle II

We report on the construction, operation, and performance of the Time-of-Propagation detector with imaging used for the Belle II experiment running at the Super-KEKB $e^+e^-$ collider. This detector is located in the central barrel region and uses Cherenkov light to provide particle identification among hadrons. The Cherenkov light is radiated in highly polished bars of synthetic fused silica (quartz) and transported to the ends of the bars via total internal reflection. One bar end is instrumented with finely segmented micro-channel-plate photomultiplier tubes to record the light, while the other end has a mirror attached to reflect the photons back to the instrumented end. Both the propagation times and hit positions of the Cherenkov photons are measured; these depend on the Cherenkov angle and together provide good discrimination among charged pions, kaons, and protons with momenta up to around 4 GeV/$c$. To date, the detector has been used to record and analyze almost 600 fb$^{-1}$ of Belle II data.

hep-ex↗

arXiv2018

Charmless two-body decays at Belle and prospects at Belle II

Charmless hadronic $B$ decays are a good testing ground for the Standard Model (SM) of Particle Physics. The dominant amplitudes are CKM suppressed tree diagrams and/or $ b\to s$ or $b\to d$ loop ("penguin") diagrams. Non-SM particle could appear in the loop, and hence these decays are sensitive to search for New Physics (NP). Some of the recent measurements of two-body charmless hadronic $B$ decays from Belle and their prospects at Belle II are discussed.

hep-ex↗

arXiv2018

Measurements of $B^0\to J/ψπ^0$ and other CP violating modes at Belle

We report the recent measurements of $B^0\to J/ψπ^0$ and other CP violation modes based on the data collected by the Belle experiment at the KEKB collider. The CP asymmetry parameters for the decay $B^0\to J/ψπ^0$ have previously been measured by BaBar and Belle experiments, but the results of mixing induced CP asymmetry $[S=-η_f\sin(2ϕ_1)]$ were not in good agreement with each other. Furthermore, the BaBar result lies outside the physically allowed region. Previous Belle measurements were based on $535\times10^6$ $B\bar{B}$ pairs. We updated the measurements using the final Belle data set of $772\times10^6$ $B\bar{B}$ pairs. The CP asymmetry parameters from a charmless $B^0\to K_S^0π^0π^0$ decay using final Belle data set and measurement of $\cos(2ϕ_1)$ in $B^0\to D^{(*)}h^0$ using joint BaBar and Belle analysis are also discussed.

hep-ex↗

arXiv2018

Recent Belle results related to $π-K$ interactions

We report the recent results related to $π-K$ interactions based on the data collected by the Belle experiment at the KEKB collider. This includes the branching fraction and $CP$ asymmetry measurements of $B^+\to K^+K^-π^+$ decay, search for the $Λ_c^+\toϕpπ^0$, $Λ_c^+\to P_s^+π^0$ decays, branching fraction measurement of $Λ_c^+\to K^-π^+pπ^0$, first observation of doubly Cabibbo-suppressed decay $Λ_c^+\to K^+π^-p$, and the measurement of CKM angle $ϕ_3$ ($γ$) with a model-independent Dalitz plot analysis of $B^{\pm}\to DK^{\pm},D\to K_S^0π^+π^-$ decay.

hep-ex↗

arXiv2017

Belle II iTOP Optics: Design, Construction and Performance

The imaging-Time-of-Propogation (iTOP) counter is a new type of ring-imaging Cherenkov counter developed for particle identification at the Belle II experiment. It consists of 16 modules arranged azimuthally around the beam line. Each module consists of one mirror, one prism and two quartz bar radiators. Here we describe the design, acceptance test, alignment, gluing and assembly of the optical components. All iTOP modules have been successfully assembled and installed in the Belle II detector by the middle of 2016. After installation, laser and cosmic ray data have been taken to test the performance of the modules. First results from these tests are presented.

physics.ins-det↗

arXiv2017

Recent results of charmed baryon decays at Belle

We report the recent results of charmed baryon decays, based on the data collected by the Belle experiment at the KEKB collider. This includes the observation of the doubly Cabibbo-suppressed decay $Λ_c^+\toπ^-K^+p$, search for the decay $Λ_c^+\toϕp π^0$, and the branching fraction measurement of $Λ_c^+\toπ^+K^-pπ^0$.

hep-ex↗

arXiv2017

Measurements of CKM angles at Belle

In this review recent studies on $CP$ violation and related hadronic $B$ decays by the Belle experiment, in particular measurements of CKM angles $ϕ_1$ and $ϕ_2$ are reported.

hep-ex↗

arXiv2016

Charmless $B_s^0$ decays at Belle

We report on recent results on charmless hadronic and radiative rare $B_s^0$ decays, based on the data collected by the Belle experiment at the KEKB $e^+e^-$ collider. These include the studies of $B_s^0\rightarrow K^0\bar{K^0}$, $B_s^0\rightarrowϕγ$ and $B_s^0\rightarrowγγ$.

hep-ex↗

arXiv2015

Recent results on charmless hadronic $B$ decays at Belle

Two-body charmless hadronic decays of $B$ mesons are important for determining Standard Model parameters and for detecting the presence of new physics. We present recent results from the Belle experiment on the charmless hadronic decays $B\rightarrow ηπ^0$ and $B\rightarrow π^0 π^0$.

hep-ex↗

arXiv2013

Measurements of b hadron lifetimes and effective lifetimes at LHCb

Precision measurements of b-hadron lifetimes are a key goal of the LHCb experiment. In the B_s sector, the measurement of the effective lifetimes for B_s mesons decaying to CP-odd, CP-even and flavor specific final states are essential for constraining the B_s mixing parameters, $ΔΓ_s$, the average width, $Γ_s$, and the CP-violating phase, $ϕ_s$. Measurements of $b$ baryon lifetimes are also important to test theoretical models. We present the latest results from LHCb on these topics.

hep-ex↗