Here, we present a measurement of angular observables and a test of lepton flavor universality in the B → K*ℓ+ℓ- decay, where ℓ is either e or μ . The analysis is performed on a data sample ...corresponding to an integrated luminosity of 711fb-1 containing 772×106 B B ¯ pairs, collected at the Υ ( 4S ) resonance with the Belle detector at the asymmetric-energy e+e- collider KEKB. The finding is consistent with standard model (SM) expectations, where the largest discrepancy from a SM prediction is observed in the muon modes with a local significance of 2.6σ .
We report here measurement of the cross section of e+e- → π+π-ψ ( 2S ) between 4.0 and 5.5 GeV, based on an analysis of initial state radiation events in a 980fb-1 data sample recorded with the Belle ...detector. The properties of the Y ( 4360 ) and Y ( 4660 ) states are determined. Fitting the mass spectrum of π+π-ψ ( 2S ) with two coherent Breit-Wigner functions, we discover two solutions with identical mass and width but different couplings to electron-positron pairs: MY ( 4360 ) = ( 4347±6±3 ) MeV / c2 , Γ Y ( 4360 ) = ( 103±9±5 ) MeV , MY ( 4660 ) = ( 4652±10±8 ) MeV / c2 , Γ Y ( 4660 ) = ( 68±11±1 ) MeV ; and B Y ( 4360 ) → π+π-ψ ( 2S ) · Γ Y ( 4360 ) e+e-= ( 10.9±0.6±0.7 ) eV and B Y ( 4660 ) → π+π-ψ ( 2S ) · Γ Y ( 4660 ) e+e-= ( 8.1±1.1±0.5 ) eV for one solution; or B Y ( 4360 ) → π+π-ψ ( 2S ) · Γ Y ( 4360 ) e+e-= ( 9.2±0.6±0.6 ) eV and B Y ( 4660 ) → π+π=ψ ( 2S ) · Γ Y ( 4660 ) e+e-= ( 2.0±0.3±0.2 ) eV for the other. Here, the first errors are statistical and the second systematic. Evidence for a charged charmoniumlike structure at 4.05GeV / c2 is observed in the π±ψ ( 2S ) intermediate state in the Y ( 4360 ) decays. decays.
We present the results of an amplitude analysis of B¯0→J/ψK-π+ decays. A new charged charmoniumlike state Zc(4200)+ decaying to J/ψπ+ is observed with a significance of 6.2σ. The mass and width of ...the Zc(4200)+ are 4196+31-29+17-13 MeV/c2 and 370+70-70+70-132 MeV, respectively; the preferred assignment of the quantum numbers is JP=1+. In addition, we find evidence for Zc(4430)+→J/ψπ+. The analysis is based on a 711 fb-1 data sample collected by the Belle detector at the asymmetric-energy e+e- collider KEKB.
We report a study of the charmless hadronic decay of the charged B meson to the three-body final state K+K−π+. The results are based on a data sample that contains 772×106 BB¯ pairs collected at the ...ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. The measured inclusive branching fraction and direct CP asymmetry are (5.38±0.40±0.35)×10−6 and −0.170±0.073±0.017, respectively, where the first uncertainties are statistical and the second are systematic. The K+K− invariant mass distribution of the signal candidates shows an excess in the region below 1.5 GeV/c2, which is consistent with the previous studies from BABAR and LHCb. In addition, strong evidence of a large direct CP asymmetry is found in the low K+K− invariant-mass region.
We present results from a study of X(3872)→ππJ/ψ decays produced via exclusive B→KX(3872) decays. We determine the mass to be MX(3872)=(3871.85±0.27(stat)±0.19(syst)) MeV, a 90% confidence level ...upper limit on the natural width of ΓX(3872)<1.2 MeV, the product branching fraction B(B+→K+X(3872))×B(X(3872)→π+π-J/ψ)=(8.63±0.82(stat)±0.52(syst))×10-6, and a ratio of branching fractions B(B0→K0X(3872))/B(B+→K+X(3872))=0.50±0.14(stat)±0.04(syst). The difference in mass between the X(3872)→π+π-J/ψ signals in B+ and B0 decays is ΔMX(3872)=(-0.71±0.96(stat)±0.19(syst)) MeV. A search for a charged partner of the X(3872) in the decays B0→K-X+ or B+→K0X+, X+→π+π0J/ψ resulted in upper limits on the product branching fractions for these processes that are well below expectations for the case that the X(3872) is the neutral member of an isospin triplet. In addition, we examine possible JPC quantum number assignments for the X(3872) based on comparisons of angular correlations between final state particles in X(3872)→π+π-J/ψ decays with simulated data for JPC values of 1++ and 2-+. We examine the influence of ρ-ω interference in the M(π+π-) spectrum. The analysis is based on a 711 fb-1 data sample that contains 772×106 BB meson pairs collected at the Υ(4S) resonance in the Belle detector at the KEKB e+e- collider.
We report a new measurement of the exclusive e+e−→D(*)±D*∓ cross sections as a function of the center-of-mass energy from the D(*)±D*∓ threshold through s=6.0 GeV, using the initial-state radiation ...technique. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 951 fb−1. The accuracy of the cross section measurement is increased by a factor of 2 over the first Belle study. We perform the first angular analysis of the e+e−→D*±D*∓ process and decompose this exclusive cross section into three components corresponding to the D* helicities.
We report the first search for the JPC=0−− glueball in ϒ(1S) and ϒ(2S) decays with data samples of (102±2)×106 and (158±4)×106 events, respectively, collected with the Belle detector. No significant ...signals are observed in any of the proposed production modes, and the 90% credibility level upper limits on their branching fractions in ϒ(1S) and ϒ(2S) decays are obtained. The inclusive branching fractions of the ϒ(1S) and ϒ(2S) decays into final states with a χc1 are measured to be B(ϒ(1S)→χc1+anything)=(1.90±0.43(stat)±0.14(syst))×10−4 with an improved precision over prior measurements and B(ϒ(2S)→χc1+anything)=(2.24±0.44(stat)±0.20(syst))×10−4 for the first time.
We report a new sensitive search for CPT violation, which includes improved measurements of the CPT-violating parameter z and the total decay-width difference normalized to the averaged width Delta ...Gamma sub(d)/Gamma sub(d) of the two B sub(d) mass eigenstates. The results are based on a data sample of 535 x 10 super(6) BB pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e super(+)e super(-) collider. We obtain Re(z) = +1.9 + or - 3.7(stat) + or - 3.3(syst) x 10 super(-2), Im(z) = -5.7 + or - 3.3(stat) + or - 3.3(syst) x 10 super(-3), and Delta Gamma sub(d)/Gamma sub(d) = -1.7+ 1.8(stat) + or - 1.1 (syst) x 10 super(-2), all of which are consistent with zero. This is the most precise single measurement of these parameters in the neutral B-meson system to date.
Momentum, track angle and impact parameter resolution are key performance parameters that tracking detectors are optimised for. This report presents analytic expressions for the resolution of these ...parameters for equal and equidistant tracking layers. The expressions for the contribution from position resolution are based on the Gluckstern formulae and are well established. The expressions for the contribution from multiple scattering using optimum weights are discussed in detail.
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