Showing papers by "Prafulla Kumar Behera published in 2001"
TL;DR: The standard model CP violation parameter sin2 phi(1) is measured based on a data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider and it is concluded that the neutral B meson system is observed.
Abstract: We present a measurement of the standard model $\mathrm{CP}$ violation parameter $\mathrm{sin}2{\ensuremath{\varphi}}_{1}$ based on a $29.1{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. One neutral $B$ meson is fully reconstructed as a $J/\ensuremath{\psi}{K}_{S}$, $\ensuremath{\psi}(2S){K}_{S}$, ${\ensuremath{\chi}}_{c1}{K}_{S}$, ${\ensuremath{\eta}}_{c}{K}_{S}$, $J/\ensuremath{\psi}{K}_{L}$, or $J/\ensuremath{\psi}{K}^{*0}$ decay and the flavor of the accompanying $B$ meson is identified from its decay products. From the asymmetry in the distribution of the time intervals between the two $B$ meson decay points, we determine $\mathrm{sin}2{\ensuremath{\varphi}}_{1}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.99\ifmmode\pm\else\textpm\fi{}0.14(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.06(\mathrm{syst})$. We conclude that we have observed $\mathrm{CP}$ violation in the neutral $B$ meson system.
576 citations
TL;DR: In this paper, the branching fraction of the inclusive radiative B meson decay B→Xsγ was measured to be 3.36±0.53(stat)± 0.42(sys)+0.50−0.54(th))×10−4.
199 citations
TL;DR: In this article, a measurement of the standard model violation parameter is presented based on a 10.5-sample data set collected at the KEKB asymmetric collider, and the flavor of the accompanying $B$ meson is identified from its charged particle decay products from the asymmetry in the distribution of the time interval between the two $B€-meson decay points.
Abstract: We present a measurement of the standard model $\mathrm{CP}$ violation parameter $\mathrm{sin}2{\ensuremath{\varphi}}_{1}$ (also known as $\mathrm{sin}2\ensuremath{\beta}$) based on a $10.5{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB asymmetric ${e}^{+}{e}^{\ensuremath{-}}$ collider. One neutral $B$ meson is reconstructed in the $J/\ensuremath{\psi}{K}_{S}$, $\ensuremath{\psi}(2S){K}_{S}$, ${\ensuremath{\chi}}_{c1}{K}_{S}$, ${\ensuremath{\eta}}_{c}{K}_{S}$, $J/\ensuremath{\psi}{K}_{L}$, or $J/\ensuremath{\psi}{\ensuremath{\pi}}^{0}$ $\mathrm{CP}$-eigenstate decay channel and the flavor of the accompanying $B$ meson is identified from its charged particle decay products. From the asymmetry in the distribution of the time interval between the two $B$-meson decay points, we determine $\mathrm{sin}2{\ensuremath{\varphi}}_{1}{\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.58}_{\ensuremath{-}0.34}^{+0.32}(\mathrm{stat}{)}_{\ensuremath{-}0.10}^{+0.09}(\mathrm{syst})$.
81 citations
TL;DR: In this article, a determination of the mixing parameter was made based on the time evolution of dilepton yields in the Euclidean space, and the proper-time difference distributions for same-sign and opposite-sign dilepton events were simultaneously fitted to an expression containing $\ensuremath{\Delta{m}_{d}$ as a free parameter.
Abstract: We report a determination of the ${B}_{d}^{0}\ensuremath{-}{\overline{B}}_{d}^{0}$ mixing parameter $\ensuremath{\Delta}{m}_{d}$ based on the time evolution of dilepton yields in $\ensuremath{\Upsilon}(4S)$ decays. The measurement is based on a $5.9{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing $\ensuremath{\Delta}{m}_{d}$ as a free parameter. Using both muons and electrons, we obtain $\ensuremath{\Delta}{m}_{d}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.463\ifmmode\pm\else\textpm\fi{}0.008(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.016(\mathrm{syst}){\mathrm{ps}}^{\ensuremath{-}1}$. This is the first determination of $\ensuremath{\Delta}{m}_{d}$ from time evolution measurements at the $\ensuremath{\Upsilon}(4S)$. We also place limits on possible $\mathrm{CPT}$ violations.
67 citations
TL;DR: In this paper, the authors report measurements of the branching fractions for $B^0\to\pi+\pi-$, $K^+K^-$, K^+k^-$ and K^ 0\pi^0.
Abstract: We report measurements of the branching fractions for $B^0\to\pi^+\pi^-$, $K^+\pi^-$, $K^+K^-$ and $K^0\pi^0$, and $B^+\to\pi^+\pi^0$, $K^+\pi^0$, $K^0\pi^+$ and $K^+\overline{K}{}^0$. The results are based on 10.4 fb$^{-1}$ of data collected on the $\Upsilon$(4S) resonance at the KEKB $e^+e^-$ storage ring with the Belle detector, equipped with a high momentum particle identification system for clear separation of charged $\pi$ and $K$ mesons. We find ${\cal B}(B^0\to\pi^+\pi^-) =(0.56^{+0.23}_{-0.20}\pm 0.04)\times 10^{-5}$, ${\cal B}(B^0\to K^+\pi^-) =(1.93^{+0.34 +0.15}_{-0.32 -0.06})\times 10^{-5}$, ${\cal B}(B^+\to K^+\pi^0) =(1.63^{+0.35 +0.16}_{-0.33 -0.18})\times 10^{-5}$, ${\cal B}(B^+\to K^0\pi^+) =(1.37^{+0.57 +0.19}_{-0.48 -0.18})\times 10^{-5}$, and ${\cal B}(B^0\to K^0\pi^0) =(1.60^{+0.72 +0.25}_{-0.59 -0.27})\times 10^{-5}$, where the first and second errors are statistical and systematic. We also set upper limits of ${\cal B}(B^+\to\pi^+\pi^0)<1.34\times 10^{-5}$, ${\cal B}(B^0\to K^+K^-)<0.27\times 10^{-5}$, and ${\cal B}(B^+\to K^+\overline{K}{}^0)<0.50\times 10^{-5}$ at the 90% confidence level.
58 citations
TL;DR: In this article, measurements for two-body charmless hadronic B decays with an η′ meson in the final state using 111×106 B pairs collected with the Belle detector.
54 citations
18 citations
TL;DR: The first observations of the B-->D+K-, D(*0)K-, and D(*+)K- decay processes are reported, using a data sample accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) storage ring.
Abstract: We report observations of the Cabibbo suppressed decays B{yields}D{sup (*)}K{sup -} using a 10.4 fb{sup -1} data sample accumulated at the {Upsilon}(4S) resonance with the Belle detector at the KEKB e{sup +}e{sup -} storage ring. We find that the ratios of Cabibbo suppressed to Cabibbo favored branching fractions are B(B{sup -}{yields}D{sup 0}K{sup -})/B(B{sup -} {yields}D{sup 0}{pi}{sup -})= 0.079{+-} 0.009{+-} 0.006 , B({bar B}{sup 0} {yields}D{sup +}K{sup -})/B({bar B}{sup 0 }{yields} D{sup +}{pi}{sup -}) =0.068 {+-}0.015 {+-}0.007 , B(B{sup -}{yields} D{sup *0}K{sup -}) /B(B{sup -} {yields}D{sup *0}{pi}{sup -})= 0.078{+-} 0.019{+-} 0.009 , and B({bar B}{sup 0}{yields} D{sup *+}K{sup -})/ B({bar B}{sup 0}{yields} D{sup *+}{pi}{sup -})=0.074{+-}0.015{+-} 0.006 . These are the first observations of the B{yields}D{sup +}K{sup -} , D{sup *0}K{sup -} , and D{sup *+}K{sup -} decay processes.
18 citations
TL;DR: In this article, the mean multiplicity and momentum spectrum of neutral pions from the decays of the ∆-Upsilon (4S) resonance was measured using the Belle detector operating at the KEKB (e + ∆ + e + e^{\ensuremath{-}}$ storage ring.
Abstract: Using the Belle detector operating at the KEKB ${e}^{+}{e}^{\ensuremath{-}}$ storage ring, we have measured the mean multiplicity and momentum spectrum of neutral pions from the decays of the $\ensuremath{\Upsilon}(4S)$ resonance. We measure a mean of $4.70\ifmmode\pm\else\textpm\fi{}0.04\ifmmode\pm\else\textpm\fi{}0.22$ neutral pions per $\ensuremath{\Upsilon}(4S)$ decay.
16 citations
TL;DR: The first observation of the exclusive decay process was reported in this article, where the authors used a sample of 11.2M meson pairs collected in the Belle detector at the KEKB asymmetric energy collider.
Abstract: We report the first observation of the exclusive decay process $B\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}_{1}(1270)$ using a sample of $11.2M$ $B\overline{B}$ meson pairs collected in the Belle detector at the KEKB asymmetric energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. We measure branching fractions of $B[{B}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}_{1}^{0}(1270)]\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(1.30\ifmmode\pm\else\textpm\fi{}0.34\ifmmode\pm\else\textpm\fi{}0.32)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ and $B[{B}^{+}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}_{1}^{+}(1270)]\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(1.80\ifmmode\pm\else\textpm\fi{}0.34\ifmmode\pm\else\textpm\fi{}0.39)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, where the first error is statistical and the second is systematic. These modes constitute approximately $15%$ of the total number of $B\ensuremath{\rightarrow}J/\ensuremath{\psi}X$ decays. No evidence is seen for $B\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}_{1}(1400)$ and we set an upper limit for this branching fraction.
15 citations
TL;DR: In this article, the rate asymmetry between charge conjugate modes was measured on a data sample of 11.1 million B B bar events recorded on the Upsilon(4S) resonance by the Belle experiment at KEKB.
Abstract: We search for direct CP violation in flavor specific B -> K pi decays by measuring the rate asymmetry between charge conjugate modes. The search is performed on a data sample of 11.1 million B B bar events recorded on the Upsilon(4S) resonance by the Belle experiment at KEKB. We measure 90% confidence intervals in the partial rate asymmetry A_CP of -0.25 < A_CP(K-/+ pi+/-) < 0.37, -0.40 < A_CP(K-/+ pi^0) < 0.36, and -0.53 < A_CP(K^0 pi-/+) < 0.82. By combining the K-/+ pi+/- and K-/+ pi^0 final states, we conclude that -0.22 < A_CP[K-/+(pi+/- + pi^0)] < 0.25 at the 90% confidence level.
Posted Content•
TL;DR: In this article, a search for the flavor-changing neutral current decay was conducted using a 295 fb$^{-1}$ data sample accumulated at the $Upsilon(4S) resonance with the Belle detector at the KEKB $e^{+}e^{-} storage ring.
Abstract: We report a search for the flavor-changing neutral current decay $B \to X_{s} \ell^{+} \ell^{-}$ using a 295 fb$^{-1}$ data sample accumulated at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB $e^{+}e^{-}$ storage ring We observe evidence for $B\to K\mu^+\mu^-$ and report the preliminary branching fraction of ${\cal B}(B \to K \mu^{+} \mu^{-}) =
(099^{+039}_{-032}^{+013}_{-015}) \times 10^{-6}$ We also set the following 90% confidence level upper limits on the branching fractions for exclusive and inclusive decays, ${\cal B}(B \to K e^{+} e^{-}) < 12 \times 10^{-6}$, ${\cal B}(B \to K^*(892) e^{+} e^{-}) < 51 \times 10^{-6}$, ${\cal B}(B \to K^*(892) \mu^{+} \mu^{-}) < 30 \times 10^{-6}$, ${\cal B}(B \to X_{s} e^{+} e^{-}) < 101 \times 10^{-6}$, ${\cal B}(B \to X_{s} \mu^{+} \mu^{-}) < 191 \times 10^{-6}$