Combined Time-Dependent CP Violation Measurements by the B factory experiments BaBar and Belle

During the 2000s, the BaBar experiment at SLAC in Stanford/USA and the Belle experiment at KEK in Tsukuba/Japan performed a very successful flavor physics program. In particular, BaBar and Belle discovered CP violation in the neutral and charged B meson system. In this talk, we present the results of two measurements from a novel analysis campaign by the former 'friendly competitors'. The novel approach combines the integrated luminosity of about 1.1 inverse attobarn collected by both experiments in single physics analyses. The first combined measurement presented is a time-dependent CP violation measurement of $B^{0} \to D^{(*)}_{CP} h^{0}$ decays, where the light neutral hadron $h^{0}$ is a $\pi^{0}$, $\eta$ or $\omega$ meson, and the neutral $D$ meson is reconstructed in decays to the two-body CP eigenstates $K^{+}K^{-}$, $K_{S}^{0}\pi^{0}$ or $K_{S}^{0}\omega$. A first observation of CP violation governed by mixing-induced CP violation according to $\sin{2\beta}$ is reported. The second combined measurement presented is a time-dependent Dalitz plot analysis of $B \to D^{(*)} h^{0}$ with $D \to K_{S}^{0} \pi^{+} \pi^{-}$ decays. These decays provide an experimentally elegant and powerful approach to access $\cos{2\beta}$ in addition to $\sin{2\beta}$, and can therefore resolve an ambiguity in the determination of the apex of the CKM Unitarity Triangle. The second combined measurement is technically demanding and includes a full Dalitz plot amplitude analysis of $D \to K_{S}^{0} \pi^{+} \pi^{-}$ decays that is performed on a high-statistics charm data set. We report the first evidence for \cos{2\beta}>0, an observation of CP violation, and the exclusion of the second solution of the CKM Unitarity Triangle of $\beta = (68.1 \pm 0.7)^\circ$ at a significance of 7.3 standard deviations. During the talk, the speaker will attempt to highlight various unique physics features of the B factory experiments that include diverse interference phenomena, such as variations of Young's double slit experiment, or the Einstein-Podolsky-Rosen correlation that can be exploited in the measurements. &nbsp;</p

Measurement of the data to MC ratio of photon reconstruction efficiency of the Belle II calorimeter using radiative muon pair events

This note presents photon detection eciency data-to-simulation ratio distributions in the barrelregion of the electromagnetic calorimeter of the Belle II detector at the SuperKEKB asymmetricenergy electron-positron collider. They are computed using 71:2 f

Measurement of the Resonant and Non-Resonant Branching Ratios in Ξc0→Ξ0K+K−\Xi_{c}^{0} \rightarrow \Xi^{0} K^+ K^-

Using the entire data sample of $980$ $fb^{-1}$ integrated luminosity collected with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider, we present an amplitude analysis measuring the branching fractions of the Cabibbo-allowed, $W$-exchange resonant decay $\Xi_{c}^{0} \rightarrow \Xi^{0} \phi (\to K^+ K^-)$ with a polarized $\phi$ and the non-resonant decay via a direct process $\Xi_{c}^{0} \rightarrow \Xi^{0} K^+ K^-$. We present these measurements, relative to the normalization mode $\Xi^{-}\pi^{+}$, and find branching ratios $\frac{\mathcal{B}(\Xi_{c}^{0} \rightarrow \Xi^{0} \phi (\rightarrow K^{+}K^{-}))}{\mathcal{B}(\Xi_{c}^{0} \rightarrow \Xi^{-} \pi^{+})} = 0.036 \pm 0.004 (stat.) \pm 0.002 (syst.)$ and $\frac{\mathcal{B}(\Xi_{c}^{0} \rightarrow \Xi^{0} K^{+} K^{-})}{\mathcal{B}(\Xi_{c}^{0} \rightarrow \Xi^{-} \pi^{+})} = 0.039 \pm 0.004 (stat.) \pm 0.002 (syst.)$ which suggest that only minor cusping peaks occur in the combinatorial background of $\Omega^{*-} \to \Xi^{0}K^{-}$ due to these $\Xi_{c}^{0}$ decays

Measurements of the branching fractions of the semileptonic decays Ξc0→Ξ−ℓ+νℓ\Xi_{c}^{0} \to \Xi^{-} \ell^{+} \nu_{\ell} and the asymmetry parameter of Ξc0→Ξ−π+\Xi_{c}^{0} \to \Xi^{-} \pi^{+}

International audienceUsing data samples of 89.5 and 711  fb-1 recorded at energies of s=10.52 and 10.58 GeV, respectively, with the Belle detector at the KEKB e+e- collider, we report measurements of branching fractions of semileptonic decays Ξc0→Ξ-ℓ+νℓ (ℓ=e or μ) and the CP-asymmetry parameter of Ξc0→Ξ-π+ decay. The branching fractions are measured to be B(Ξc0→Ξ-e+νe)=(1.31±0.04±0.07±0.38)% and B(Ξc0→Ξ-μ+νμ)=(1.27±0.06±0.10±0.37)%, and the decay parameter αΞπ is measured to be 0.63±0.03±0.01 with much improved precision compared with the current world average. The corresponding ratio B(Ξc0→Ξ-e+νe)/B(Ξc0→Ξ-μ+νμ) is 1.03±0.05±0.07, which is consistent with the expectation of lepton flavor universality. The first measured asymmetry parameter ACP=(αΞ-π++αΞ¯+π-)/(αΞ-π+-αΞ¯+π-)=0.024±0.052±0.014 is found to be consistent with zero. The first and the second uncertainties above are statistical and systematic, respectively, while the third ones arise due to the uncertainty of the Ξc0→Ξ-π+ branching fraction

Measurements of the branching fractions of semileptonic decays Ξc0→Ξ−ℓ+νℓ\Xi_{c}^{0} \to \Xi^{-} \ell^{+} \nu_{\ell} and asymmetry parameter of Ξc0→Ξ−π+\Xi_{c}^{0} \to \Xi^{-} \pi^{+} decay

Using a data sample of 89.5 fb$^{-1}$ recorded at the energy $\sqrt{s}=10.52$ GeV with the Belle detector at the KEKB $e^+e^-$ collider, we report measurements of branching fractions of semileptonic decays $\Xi_{c}^{0} \to \Xi^{-} \ell^{+} \nu_{\ell}$ ($\ell=e$ or $\mu$). Furthermore, based on an additional data sample of 711 fb$^{-1}$ at $\sqrt{s} = 10.58$ GeV, the $CP$-asymmetry parameter of $\Xi_{c}^{0} \to \Xi^{-} \pi^{+}$ decay is extracted. The branching fractions are measured to be ${\cal B}(\Xi_{c}^{0} \to \Xi^{-} e^{+} \nu_{e})=(1.72 \pm 0.10 \pm 0.12 \pm 0.50)\%$ and ${\cal B}(\Xi_{c}^{0} \to \Xi^{-} \mu^{+} \nu_{\mu})=(1.71 \pm 0.17 \pm 0.13 \pm 0.50)\%$ with much improved precision compared to the current world average. The first and the second uncertainty are statistical and systematic, respectively, while the third one arises due to the uncertainty of the $\Xi_{c}^{0} \to \Xi^{-} \pi^+$ branching fraction. The corresponding ratio ${\cal B}(\Xi_{c}^{0} \to \Xi^{-} e^{+} \nu_{e})/{\cal B}(\Xi_{c}^{0} \to \Xi^{-} \mu^{+} \nu_{\mu})$ is $1.00 \pm 0.11 \pm 0.09$, which is consistent with the expectation of lepton flavor universality. The first measured asymmetry parameter is found to be consistent with zero, ${\cal A}_{CP} = (\alpha_{\Xi^{-}\pi^{+}} + \alpha_{\bar{\Xi}^{+}\pi^{-}})/(\alpha_{\Xi^{-}\pi^{+}} - \alpha_{\bar{\Xi}^{+}\pi^{-}}) = 0.015 \pm 0.052 \pm 0.017$

Measurement of the resonant and nonresonant branching ratios in Ξc0→Ξ0K+K−\Xi_{c}^{0} \rightarrow \Xi^{0} K^+ K^-

International audienceUsing the entire data sample of 980  fb-1 integrated luminosity collected with the Belle detector at the KEKB asymmetric-energy e+e- collider, we present an amplitude analysis measuring the branching fractions of the Cabibbo-allowed, W-exchange resonant decay Ξc0→Ξ0ϕ(→K+K-) with a polarized ϕ and the nonresonant decay via a direct process Ξc0→Ξ0K+K-. We present these measurements, relative to the normalization mode Ξ-π+, and find branching ratios B(Ξc0→Ξ0ϕ(→K+K−))(BΞc0→Ξ−π+)=0.036±0.004(stat.)±0.002(syst.) and B(Ξc0→Ξ0K+K−)B(Ξc0→Ξ−π+)=0.039±0.004(stat.)±0.002(syst.), which suggest that only minor cusping peaks occur in the combinatorial background of Ω*-→Ξ0K- due to these Ξc0 decays

Search for tetraquark states XccsˉsˉX_{cc\bar{s}\bar{s}} in Ds+Ds+ (Ds∗+Ds∗+)D_{s}^{+}D_{s}^{+}~(D_{s}^{*+}D_{s}^{*+}) final states at Belle

A search for double-heavy tetraquark state candidates $X_{cc\bar{s}\bar{s}}$ decaying to $D_{s}^{+}D_{s}^{+}$ and $D_{s}^{*+} D_{s}^{*+}$ is presented for the first time using the data samples of 102 million $\Upsilon(1S)$ and 158 million $\Upsilon(2S)$ events, and the data samples at $\sqrt{s}$ = 10.52~GeV, 10.58~GeV, and 10.867~GeV corresponding to integrated luminosities of 89.5~fb$^{-1}$, 711.0~fb$^{-1}$, and 121.4~fb$^{-1}$, respectively, accumulated with the Belle detector at the KEKB asymmetric energy electron-positron collider. The invariant-mass spectra of the $D_{s}^{+}D_{s}^{+}$ and $D_{s}^{*+} D_{s}^{*+}$ are studied to search for possible resonances. No significant signals are observed, and the 90% confidence level upper limits on the product branching fractions [${\cal B}(\Upsilon(1S,2S) \to X_{cc\bar{s}\bar{s}} + anything) \times {\cal B}(X_{cc\bar{s}\bar{s}} \to D_{s}^{+}D_{s}^{+}(D_{s}^{*+} D_{s}^{*+}))$] in $\Upsilon(1S,2S)$ inclusive decays and the product values of Born cross section and branching fraction [$\sigma(e^+e^- \to X_{cc\bar{s}\bar{s}} + anything ) \times {\cal B}(X_{cc\bar{s}\bar{s}} \to D_{s}^{+}D_{s}^{+}(D_{s}^{*+} D_{s}^{*+}))$] in $e^+e^-$ collisions at $\sqrt{s}$ = 10.52~GeV, 10.58~GeV, and 10.867~GeV under different assumptions of $X_{cc\bar{s}\bar{s}}$ masses and widths are obtained

Measurement of time-dependent CPCP violation parameters in B0→K0SK0SK0SB^0 \to K_0^SK_0^SK_0^S decays at Belle

International audienceWe measure the time-dependent CP violation parameters in B0→KS0KS0KS0 decays using 772×106BB¯ pairs collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. The obtained mixing-induced and direct CP asymmetries are -0.71±0.23 (stat)±0.05 (syst) and 0.12±0.16 (stat)±0.05 (syst), respectively. These values are consistent with the Standard Model predictions. The significance of CP violation differs from zero by 2.5 standard deviations