We search for CP violation in the charged charm meson decay D+→π+π0, based on a data sample corresponding to an integrated luminosity of 921 fb−1 collected by the Belle experiment at the KEKB e+e− ...asymmetric-energy collider. The measured CP-violating asymmetry is +2.31±1.24(stat)±0.23(syst)%, which is consistent with the standard model prediction and has a significantly improved precision compared to previous results.
Using data samples of 89.5 fb−1, 711.0 fb−1, and 121.4 fb−1 collected with the Belle detector at the KEKB asymmetric-energy e+e− collider at center-of-mass energies 10.52, 10.58, and 10.867 GeV, ...respectively, we study the exclusive reactions e+e−→γχcJ (J=0, 1, 2) and e+e−→γηc. A significant γχc1 signal is observed for the first time at s=10.58 GeV with a significance of 5.1σ including systematic uncertainties. No significant excesses for γχc0, γχc2, and γηc final states are found, and we set 90% credibility level upper limits on the Born cross sections (σB) at 10.52 GeV, 10.58 GeV, and 10.867 GeV. Together with cross sections measured by BESIII at lower center-of-mass energies, the energy dependency of σB(e+e−→γχc1) is obtained.
This paper presents a search for the rare flavor-changing neutral current process B0→K*0τ+τ- using data taken with the Belle detector at the KEKB asymmetric energy $e^+$$e^-$ collider. The analysis ...is based on the entire $\Upsilon$$(4S)$ resonance data sample of $711$ $\mathrm{fb}^{-1}$, corresponding to $772 × 10^6$$B$$\bar{B}$ pairs. In our search we fully reconstruct the companion $B$ meson produced in the process $e^+$$e^-$ → $\Upsilon$$(4S)$ → $B$$\bar{B}$ from its hadronic decay modes and look for the decay B0→K*0τ+τ- in the rest of the event. No evidence for a signal is found. We report an upper limit on the branching fraction $\mathscr{B}$(B0→K*0τ+τ-) < $3.1 × 10^{-3}$ at 90% confidence level. This is the first direct limit on $\mathscr{B}$(B0→K*0τ+τ-).
We report a search for X(3872) and X(3915) in B+→χc1π0K+ decays. We set an upper limit of B(B+→X(3872)K+)×B(X(3872)→χc1π0)<8.1×10−6 and B(B+→X(3915)K+)×B(X(3915)→χc1π0)<3.8×10−5 at 90% confidence ...level. We also measure B(X(3872)→χc1π0)/B(X(3872)→J/ψπ+π−)<0.97 at 90% confidence level. The results reported here are obtained from 772×106 BB events collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider.
Using a data sample of 980 fb–1 of $e^+e^–$ annihilation data taken with the Belle detector operating at the KEKB asymmetric-energy $e^+e^–$ collider, we report the results of a study of the decays ...of the $Ω^0_c$ charmed baryon into hadronic final states. We report the most precise measurements to date of the relative branching fractions of the $Ω^0_c$ into $Ω^–π^+π^0, Ω^–π^+π^–π^+$, $Ξ^–K^–π^+π^+$, and $Ξ^0K^–π^+$, as well as the first measurements of the branching fractions of the $Ω^0_c$ into $Ξ^–\overline{K}^0π^+$, $Ξ^0\overline{K}^0$, and $Λ\overline{K}^0\overline{K}^0$, all with respect to the $Ω^–π^+$ decay. In addition, we investigate the resonant substructure of these modes. Finally, we present a limit on the branching fraction for the decay $Ω^0_c→Σ^+K^–K^–π^+$.
We present the results of the first Dalitz plot analysis of the decay D 0 → K-π +η. The analysis is performed on a data set corresponding to an integrated luminosity of 953 fb-1 collected by the ...Belle detector at the asymmetric-energy e+e- KEKB collider. The Dalitz plot is well described by a combination of the six resonant decay channels K- * (892)0 η, K-a0(980)+, K-a2(1320)+, K¯ * (1410)0 η, K* (1680)-π + and K* 2 (1980)-π +, together with Kπ and Kη S-wave components. The decays K* (1680)- → K-η and K* 2 (1980)- → K-η are observed for the first time. We measure ratio of the branching fractions, B(D0→K-π+η) B(D0→K=π+) = 0.500 ± 0.002(stat) ± 0.020(syst) ± 0.003(BPDG). Using the Dalitz fit result, the ratio B(K*(1680)→Kη) B(K*(1680)→Kπ) is measured to be 0.11±0.02(stat)+0.06 =0.04(syst)± 0.04(BPDG); this is much lower than the theoretical expectations (≈ 1) made under the assumption that K* (1680) is a pure 1 3D1 state. The product branching fraction B(D 0 → K* 2 (1980)- → K-ηπ +) = (2.2 +1.7 -1.9 ) × 10-4 is determined. In addition, the πη' contribution to the a0(980)± resonance shape is confirmed with 10.1σ statistical significance using the three-channel Flatté model. We also measure B(D 0 → K¯ * (892)0 η) = (1.41+0.13 -0.12)%. This is consistent with, and more precise than, the current world average (1.02 ± 0.30)%, deviates with a significance of more than 3σ from the theoretical predictions of (0.51-0.92)%.
We report inclusive and exclusive measurements for χc1 and χc2 production in B decays. We measure B(B → χc1X)= (3.03 ± 0.05(stat) ± 0.24(syst)) × 10$-$3 and B(B → χc2X)= (0.70 ± 0.06(stat) ± ...0.10(syst)) × 10$-$3 . For the first time, χc2 production in exclusive B decays in the modes B0 → χc2π $-$K+ and B+ → χc2π+π$-$K+ has been observed, along with first evidence for the B+ → χc2π+K$0\atop{S}$ decay mode. For χc1 production, we report the first observation in the B+ → χc1π+π$-$K+, B0 → χc1π+π$-$K$0\atop{S}$ and B0 → χc1π0π$-$K+ decay modes. Using these decay modes, we observe a difference in the production mechanism of χc2 in comparison to χc1 in B decays. In addition, we report searches for X(3872) and χc1(2P) in the B+ → (χc1π+π$-$)K+ decay 3 mode. The reported results use 772 × 106 B$\overline{B}$ events collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e$-$ collider.
We report the first observation of the double strange baryon Ξ(1620)^{0} in its decay to Ξ^{-}π^{+} via Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+} decays based on a 980 fb^{-1} data sample collected with the Belle ...detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The mass and width are measured to be 1610.4±6.0(stat)_{-4.2}^{+6.1} (syst) MeV/c^{2} and 59.9±4.8(stat)_{-7.1}^{+2.8}(syst) MeV, respectively. We obtain 4.0σ evidence of the Ξ(1690)^{0} with the same data sample. These results shed light on the structure of hyperon resonances with strangeness S=-2.
We present a measurement of the branching fraction and the longitudinal polarization fraction of B0->p+p- decays, as well as the time-dependent CP violating parameters in decays into longitudinally ...polarized p+p- pairs with Belle's final data set of 772x106 BB pairs, at the Y(4S) resonance, collected at the asymmetric-energy e+e- collider KEKB.
Search for the decay B s 0 → η η Nath, K. J.; Adachi, I.; Aihara, H. ...
Physical review. D,
01/2022, Letnik:
105, Številka:
1
Journal Article
Recenzirano
We report results from a search for the decay $B^0_s$ → $ηη$ using 121.4 fb-1 of data collected at the $Υ(5S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We do ...not observe any signal and set an upper limit on the branching fraction of 14.3 x 10-5 at 90% confidence level. This result represents a significant improvement over the previous most stringent limit.
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