arXiv subjects

J. B. Singh

Publications and source records attributed to J. B. Singh.

11 recordsLinked to original sources

arXiv2019

Search for the $B \to Y(4260) K, ~Y(4260) \to J/ψπ^+π^-$ decays

We report the results of a search for the $B \to Y(4260) K, ~Y(4260)\to J/ψπ^+π^-$ decays. This study is based on a data sample corresponding to an integrated luminosity of 711~fb$^{-1}$, collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We investigate the $J/ψπ^+π^-$ invariant mass distribution in the range 4.0 to 4.6 GeV/$c^2$ using both $B^+ \to J/ψπ^+π^- K^+$ and $B^0 \to J/ψπ^+π^- K^0_S$ decays. We find excesses of events above the background levels, with a significances of 2.1 and 0.9 standard deviations for charged and neutral $B \to Y(4260) K$ decays, respectively, taking into account the systematic uncertainties. These correspond to upper limits on the product of branching fractions, ${\cal B}(B^+ \to Y(4260) K^+) \times {\cal B}(Y(4260) \to J/ψπ^+ π^-) <1.4 \times 10^{-5}$ and ${\cal B}(B^0 \to Y(4260) K^0) \times {\cal B}(Y(4260) \to J/ψπ^+ π^-) <1.7 \times 10^{-5}$ at the 90\% confidence level.

hep-ex↗

arXiv2018

High Rate RPC detector for LHC

The High Luminosity LHC (HL-LHC) phase is designed to increase by an order of magnitude the amount of data to be collected by the LHC experiments. The foreseen gradual increase of the instantaneous luminosity of up to more than twice its nominal value of $10\times10^{34}\ {\rm cm}^{-1}{\rm s}^{-2}$ during Phase I and Phase II of the LHC running, presents special challenges for the experiments. The region with high pseudo rapidity ($η$) region of the forward muon spectrometer ($2.4 > |η| > 1.9$) is not equipped with RPC stations. The increase of the expected particles rate up to 2 kHz cm$^{-1}$ ( including a safety factor 3 ) motivates the installation of RPC chambers to guarantee redundancy with the CSC chambers already present. The current CMS RPC technology cannot sustain the expected background level. A new generation of Glass-RPC (GRPC) using low-resistivity glass was proposed to equip the two most far away of the four high $η$ muon stations of CMS. In their single-gap version they can stand rates of few kHz cm$^{-1}$. Their time precision of about 1 ns can allow to reduce the noise contribution leading to an improvement of the trigger rate. The proposed design for large size chambers is examined and some preliminary results obtained during beam tests at Gamma Irradiation Facility (GIF++) and Super Proton Synchrotron (SPS) at CERN are shown. They were performed to validate the capability of such detectors to support high irradiation environment with limited consequence on their efficiency.

physics.ins-det↗

arXiv2017

Physics Potential of the ICAL detector at the India-based Neutrino Observatory (INO)

The upcoming 50 kt magnetized iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) is designed to study the atmospheric neutrinos and antineutrinos separately over a wide range of energies and path lengths. The primary focus of this experiment is to explore the Earth matter effects by observing the energy and zenith angle dependence of the atmospheric neutrinos in the multi-GeV range. This study will be crucial to address some of the outstanding issues in neutrino oscillation physics, including the fundamental issue of neutrino mass hierarchy. In this document, we present the physics potential of the detector as obtained from realistic detector simulations. We describe the simulation framework, the neutrino interactions in the detector, and the expected response of the detector to particles traversing it. The ICAL detector can determine the energy and direction of the muons to a high precision, and in addition, its sensitivity to multi-GeV hadrons increases its physics reach substantially. Its charge identification capability, and hence its ability to distinguish neutrinos from antineutrinos, makes it an efficient detector for determining the neutrino mass hierarchy. In this report, we outline the analyses carried out for the determination of neutrino mass hierarchy and precision measurements of atmospheric neutrino mixing parameters at ICAL, and give the expected physics reach of the detector with 10 years of runtime. We also explore the potential of ICAL for probing new physics scenarios like CPT violation and the presence of magnetic monopoles.

physics.ins-det↗

arXiv2016

Development and characterization of single gap glass RPC

India-based Neutrino Observatory (INO) facility is going to have a 50 kton magnetized Iron CALorimeter (ICAL) detector for precision measurements of neutrino oscillations using atmospheric neutrinos. The proposed ICAL detector will be a stack of magnetized iron plates (acting as target material) interleaved with glass Resistive Plate Chambers (RPCs) as the active detector elements. An RPC is a gaseous detector made up of two parallel electrode plates having high bulk resistivity like that of float glass and bakelite. For the ICAL detector, glass is preferred over bakelite as it does not need any kind of surface treatment to achieve better surface uniformity and also the cost of associated electronics is reduced. Under the detector R&D efforts for the proposed glass RPC detector, a few glass RPCs of 1m X 1m dimension are fabricated procuring glass of ~ 2 mm thickness from one of the Indian glass manufacturers (Asahi). In the present paper, we report the characterization of RPC based on leakage current study, muon detection efficiency and noise rate studies with varying gas compositions.

physics.ins-det↗

arXiv2016

New observables for multiple-parton interactions measurements using Z + jets process at the LHC

Multiple-parton interactions play a vital role in hadron-hadron collisions. This paper presents a study of the multiple-parton interactions with simulated Z + jets events in proton-proton collisions at a centre-of-mass energy of 13 TeV. The events are simulated with POWHEG followed by hadronization and parton-showering using PYTHIA 8. The events with dimuon invariant mass in the range of 60--120 GeV are selected for the analysis. The charged particle jets, having minimum transverse momentum of 5 GeV and absolute pseudo-rapidity less than 2, are used to construct the observables for measurements of the multiple-parton interactions. The proposed observables and phase-space region presented in this paper found to have enhanced sensitivity to multiple-parton interactions. The increased sensitivity to MPI will be lead to precise constraints on the parameters of the MPI models.

hep-ph↗

arXiv2015

Study of $B \to X(3872) K π$ at Belle

We report the first observation of $B^0 \to X(3872) (K^{+}π^{-})$ and evidence for $B^+ \to X(3872) (K^{0}π^{+})$. The product of branching fractions for the former decay mode is measured to be ${\cal B}(B^0 \to X(3872) (K^+ π^-)) \times {\cal B}(X(3872) \to J/ψπ^+ π^-) = (7.9 \pm 1.3(\mbox{stat.})\pm 0.4(\mbox{syst.})) \times 10^{-6}$ and also find that $B^{0}\to X(3872) K^{*}(892)^{0}$ does not dominate the $B^{0}\to X(3872)K^{+}π^{-}$ decay mode in contrast to other charmonium states like $ψ'$. The product of branching fractions for the latter decay mode is measured to be ${\cal B}(B^+ \to X(3872) (K^0 π^+)) \times {\cal B}(X(3872) \to J/ψπ^+ π^-) = (10.6 \pm 3.0(\mbox{stat.}) \pm 0.9(\mbox{syst.})) \times 10^{-6}$. This study is based on the full and final data sample of 711~fb$^{-1}$ ($772\times 10^6 B\bar B$ pairs) collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB collider.

hep-ex↗

arXiv2015

Observation of $X(3872)$ in $B \to X(3872) Kπ$ decays

We report the first observation of $B^0 \to X(3872) (K^{+}π^{-})$ and evidence for $B^+ \to X(3872) (K^{0}π^{+})$. We measure the product of branching fractions for the former to be ${\cal B}(B^0 \to X(3872) (K^+ π^-)) \times {\cal B}(X(3872) \to J/ψπ^+ π^-) = (7.9 \pm 1.3(\mbox{stat.})\pm 0.4(\mbox{syst.})) \times 10^{-6}$ and find that $B^{0}\to X(3872) K^{*}(892)^{0}$ does not dominate the $B^{0}\to X(3872)K^{+}π^{-}$ decay mode. We also measure ${\cal B}(B^+ \to X(3872) (K^0 π^+)) \times {\cal B}(X(3872) \to J/ψπ^+ π^-) = (10.6 \pm 3.0(\mbox{stat.}) \pm 0.9(\mbox{syst.})) \times 10^{-6}$. This study is based on the full data sample of 711~fb$^{-1}$ ($772\times 10^6 B\bar B$ pairs) collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB collider.

hep-ex↗

arXiv2011

Observation of $X(3872)\to J/ψγ$ and search for $X(3872)\toψ'γ$ in B decays

We report a study of $B\to (J/ψγ) K$ and $B\to (ψ' γ)K$ decay modes using $772\times 10^{6}$ $B\bar{B}$ events collected at the Υ(4S)$ resonance with the Belle detector at the KEKB energy-asymmetric $e^+ e^-$ collider. We observe $X(3872) \to J/ψγ$ and report the first evidence for $χ_{c2} \to J/ψγ$ in $B\to (X_{c\bar{c}}γ) K$ decays, while in a search for $X(3872) \to ψ' γ$ no significant signal is found. We measure the branching fractions, $\mathcal{B}(B^{\pm} \to X(3872) K^{\pm}) \mathcal{B}(X(3872) \to J/ψγ)$ $=$ $(1.78^{+0.48}_{-0.44}\pm 0.12)\times 10^{-6}$, $\mathcal{B} (B^{\pm} \toχ_{c2} K^{\pm})$$=$ $(1.11^{+0.36}_{-0.34} \pm 0.09) \times 10^{-5}$, $\mathcal{B}(B^{\pm} \to X(3872) K^{\pm}) \mathcal{B}(X(3872) \to ψ'γ)$ $<$ $3.45\times 10^{-6}$ (upper limit at 90% C.L.) and also provide upper limits for other searches.

hep-ex↗

arXiv2008

Evidence for $B^0 \to χ_{c1} π^0$ at Belle

We present a measurement of the branching fraction for the Cabibbo- and color-suppressed $B^0 \to χ_{c1}π^0$ decay based on a data sample of $657\times 10^6$ $B\bar B$ events collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We observe a signal of $40\pm9$ events with a significance of $4.7σ$ including systematic uncertainties. The measured branching fraction is $\mathcal {B}(B^0 \to χ_{c1} π^0) = (1.12\pm 0.25(\rm {stat.})\pm 0.12({\rm syst.}))\times 10^{-5}$.

hep-ex↗

arXiv2008

Observation of $B^{\pm} \to ψ(2S) π^{\pm}$ and search for direct CP-violation

We report the first observation of $B^{\pm}\toψ(2S)π^{\pm}$, a Cabibbo- and color-suppressed decay. This analysis is based on $657\times10^{6}$ $B\overline B$ events collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB energy-asymmetric $e^+e^-$ collider. The measured branching fraction is ($2.44 \pm 0.22 \pm 0.20$)$\times 10^{-5}$ and the charge asymmetry is $\mathcal{A}=0.022 \pm 0.085 \pm 0.016$. The ratio of the branching fractions $\mathcal {B}(B^{\pm} \to ψ(2S) π^{\pm})$$/ \mathcal {B}(B^{\pm} \to ψ(2S) K^{\pm})$ $ = (3.99 \pm 0.36\pm 0.17)%$ is also determined.

hep-ex↗

arXiv2006

Observation of B^{\pm} \to χ_{c1} π^{\pm} and Search for Direct CP Violation

We report the first observation of $B^{\pm} \to χ_{c1} π^{\pm}$, the Cabibbo- and color-suppressed decay in a data sample of $386\times 10^6$~$B\bar B$ events collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We observe $55\pm10$ signal events with a statistical significance of $6.3σ$ including systematic uncertainties. The measured branching fraction and charge-asymmetry is $\mathcal {B}(B^{\pm} \to χ_{c1} π^{\pm}) = (2.2\pm 0.4\pm 0.3)\times 10^{-5}$ and $\mathcal{A}_π = 0.07 \pm 0.18\pm 0.02$, respectively. We also determine the ratio $\mathcal {B}(B^{\pm} \to χ_{c1} π^{\pm})/\mathcal {B}(B^{\pm} \to χ_{c1} K^{\pm}) = (4.3\pm 0.8\pm 0.3) %$.

hep-ex↗