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論文

Observation of a threshold cusp at the $$Lambdaeta$$ threshold in the $$pK^-$$ mass spectrum with $$Lambda_c^+ to pK^-pi^+$$ decays

Yang, S.*; 谷田 聖; Belle Collaboration*; 他196名*

Physical Review D, 108(3), p.L031104_1 - L031104_6, 2023/08

https://doi.org/10.1103/PhysRevD.108.L031104
 被引用回数：7 パーセンタイル：58.40(Astronomy & Astrophysics)

We observe a narrow peaking structure in the $$pK^{-}$$ invariant-mass spectrum near the $$Lambdaeta$$ threshold. The peak is clearly seen in 1.5 million events of $$Lambda_{c}^{+} rightarrow p K^{-} pi^{+}$$ decay using the $$980~{rm fb^{-1}}$$ data sample collected by the Belle detector at the KEKB asymmetric-energy $$e^{+}e^{-}$$ collider. We try two approaches to explain this structure: as a new resonance and as a cusp at the $$Lambdaeta$$ threshold. The best fit is obtained with a coherent sum of a Flatt$$rm{acute{e}}$$ function and a constant background amplitude with the $$chi^2/{rm n.d.f}=257/243$$ ($$p = 0.25$$), while the fits to Breit-Wigner functions are unfavored by more than 7$$sigma$$. The best fit explains the structure as a cusp at the $$Lambdaeta$$ threshold, and the obtained parameters are consistent with the known properties of $$Lambda(1670)$$. The observation gives the first identification of a threshold cusp in hadrons from the spectrum shape.

論文

Measurement of lepton mass squared moments in $$B to X_c ell bar nu_{ell}$$ decays with the Belle II experiment

Abudin$'e$n, F.*; 谷田 聖; Belle II Collaboration*; 他413名*

Physical Review D, 107(7), p.072002_1 - 072002_24, 2023/04

https://doi.org/10.1103/PhysRevD.107.072002
 被引用回数：14 パーセンタイル：78.14(Astronomy & Astrophysics)

We present measurements of the first to fourth moments of the lepton mass squared $$q^2$$ of $$B to X_c , ell, bar nu_{ell}$$ decays for $$ell = e, mu$$ and with $$X_c$$ a hadronic system containing a charm quark. These results use a sample of electron-positron collisions at the $$Upsilon(4S)$$ resonance corresponding to $$62.8 , mathrm{fb}^{-1}$$ of integrated luminosity and collected by the Belle II experiment in 2019 and 2020. To identify the $$X_c$$ system and reconstruct $$q^2$$, one of the $$B$$ mesons from an $$Upsilon(4S) to B kern 0.18emoverline{kern -0.18em B}$$ decay is fully reconstructed in a hadronic decay mode using a multivariate $$B$$ tagging algorithm. We report raw and central moments for $$ q^2 > 1.5 ; mathrm{GeV^2/c^4}$$ up to $$q^2 > 8.5 ; mathrm{GeV^2/c^4}$$, probing up to 77% of the accessible $$B to X_c , ell, bar nu_{ell}$$ phase space. This is the first measurement of moments in the experimentally challenging range of $$[ 1.5, 2.5 ] , mathrm{GeV^2/c^4}$$.

論文

Search for $$X(3872)topi^+pi^-pi^0$$ at Belle

Yin, J. H.*; 谷田 聖; Belle Collaboration*; 他193名*

Physical Review D, 107(5), p.052004_1 - 052004_8, 2023/03

https://doi.org/10.1103/PhysRevD.107.052004
 被引用回数：4 パーセンタイル：40.20(Astronomy & Astrophysics)

We present a search for the decay $$X(3872) to pi^+pi^-pi^0$$ in the $$(772pm11)times10^6$$ $$Upsilon(4S)to B bar B$$ data sample collected at the Belle detector, where the $$X(3872)$$ is produced in $$B^{pm}to K^{pm}X(3872)$$ and $$B^{0}to K_{S}^0 X(3872)$$ decays. We do not observe a signal, and set 90% credible upper limits for two different models of the decay processes: if the decay products are distributed uniformly in phase space, $$mathcal{B}(X(3872) to pi^+pi^-pi^0) < 1.3%$$; if $$M(pi^+pi^-)$$ is concentrated near the mass of the $$D^0 bar D^0$$ pair in the process $$X(3872)to D^0bar{D}^{*0}+c.c.to D^0 bar D^{0}pi^0topi^+ pi^- pi^0$$, $$mathcal{B}(X(3872) to pi^+pi^-pi^0) < 1.2times10^{-3}$$.

論文

First search for the weak radiative decays $$Lambda_c^+ to Sigma^+ gamma$$ and $$Xi_c^0 to Xi^0 gamma$$

Li, Y.*; 谷田 聖; Belle Collaboration*; 他187名*

Physical Review D, 107(3), p.032001_1 - 032001_11, 2023/02

https://doi.org/10.1103/PhysRevD.107.032001
 被引用回数：3 パーセンタイル：31.74(Astronomy & Astrophysics)

We present the first search for the weak radiative decays $$Lambda_c^+ to Sigma^+ gamma$$ and $$Xi_c^0 to Xi^0 gamma$$ using a data sample of 980~fb$$^{-1}$$ collected by the Belle detector operating at the KEKB asymmetric-energy $$e^+e^-$$ collider. There are no evident $$Lambda_c^+ to Sigma^+ gamma$$ or $$Xi_c^0 to Xi^0 gamma$$ signals. Taking the decays $$Lambda_c^+ to p K^- pi^+$$ and $$Xi_c^0 to Xi^- pi^+$$ as normalization channels, the upper limits at 90% credibility level on the ratios of branching fractions $${cal B}(Lambda_c^+ to Sigma^+ gamma)/{cal B}(Lambda_c^+ to p K^{-} pi^+) < 4.0 times 10^{-3}$$ and $${cal B}(Xi_c^0 to Xi^0 gamma)/{cal B}(Xi_c^0 to Xi^- pi^+) < 1.2 times 10^{-2}$$ are determined. We obtain the upper limits at 90% credibility level on the absolute branching fractions $${cal B}(Lambda_c^+ to Sigma^+ gamma) < 2.6 times 10^{-4}$$ and $${cal B}(Xi_c^0 to Xi^0 gamma) < 1.8 times 10^{-4}$$.

論文

Measurement of the branching fraction of $$Xi_{c}^{0}to Lambda_{c}^{+}pi^{-}$$ at Belle

Tang, S. S.*; 谷田 聖; Belle Collaboration*; 他173名*

Physical Review D, 107(3), p.032005_1 - 032005_6, 2023/02

https://doi.org/10.1103/PhysRevD.107.032005
 被引用回数：4 パーセンタイル：40.20(Astronomy & Astrophysics)

Based on a data sample of 983 fb$$^{-1}$$ collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider, we present the study of the heavy-flavor-conserving decay $$Xi_{c}^{0}to Lambda_{c}^{+}pi^{-}$$ with $$Lambda_{c}^{+}$$ reconstructed via its $$pK^{-} pi^{+}$$ decay mode. The branching fraction ratio $$mathcal{B}(Xi_{c}^{0}to Lambda_{c}^{+}pi^{-})/mathcal{B}(Xi_{c}^{0}to Xi^{-}pi^{+})$$ is measured to be $$0.38 pm 0.04 pm 0.04$$. Combing with the world average value of $$mathcal{B}(Xi_{c}^{0}to Xi^{-}pi^{+})$$, the branching fraction $$mathcal{B}(Xi_{c}^{0}to Lambda_{c}^{+}pi^{-})$$ is deduced to be $$(0.54 pm 0.05 pm 0.05 pm 0.12)%$$. Here, the uncertainties above are statistical, systematic, and from $$mathcal{B}(Xi_c^{0} to Xi^{-}pi^{+})$$, respectively.

論文

Measurement of branching fractions of $$Lambda_c^+to{}pK_S^0K_S^0$$ and $$Lambda_c^+to{}pK_S^0eta$$ at Belle

Li, L. K.*; 谷田 聖; Belle Collaboration*; 他204名*

Physical Review D, 107(3), p.032004_1 - 032004_9, 2023/02

https://doi.org/10.1103/PhysRevD.107.032004
 被引用回数：8 パーセンタイル：62.69(Astronomy & Astrophysics)

We present a study of a singly Cabibbo-suppressed decay $$Lambda_c^+to{}pK_S^0K_S^0$$ and a Cabibbo-favored decay $$Lambda_c^+to{}pK_S^0eta$$ based on 980 $$rm fb^{-1}$$ of data collected by the Belle detector, operating at the KEKB energy-asymmetric $$e^+e^-$$ collider. We measure their branching fractions relative to $$Lambda_c^+to{}pK_S^0$$: $$mathcal{B}(Lambda_c^+to{}pK_S^0K_S^0)/mathcal{B}(Lambda_c^+to{}pK_S^0)={(1.48 pm 0.08 pm 0.04)times 10^{-2}}$$ and $$mathcal{B}(Lambda_c^+to{}pK_S^0eta)/mathcal{B}(Lambda_c^+to{}pK_S^0)={(2.73pm 0.06pm 0.13)times 10^{-1}}$$. Combining with the world average $$mathcal{B}(Lambda_c^+to{}pK_S^0)$$, we have the absolute branching fractions: $$mathcal{B}(Lambda_c^+to{}pK_S^0K_S^0) = {(2.35pm 0.12pm 0.07 pm 0.12 )times 10^{-4}}$$ and $$mathcal{B}(Lambda_c^+to{}pK_S^0eta) = {(4.35pm 0.10pm 0.20 pm 0.22 )times 10^{-3}}$$. The first and second uncertainties are statistical and systematic, respectively, while the third ones arise from the uncertainty on $$mathcal{B}(Lambda_c^+to{}pK_S^0)$$. The mode $$Lambda_c^+to{}pK_S^0K_S^0$$ is observed for the first time and has a statistical significance of $$>10sigma$$. The branching fraction of $$Lambda_c^+to{}pK_S^0eta$$ has been measured with a threefold improvement in precision over previous results and is found to be consistent with the world average.

論文

Measurements of branching fractions of $$Lambda_c^+ to Sigma^+ eta$$ and $$Lambda_c^+ to Sigma^+ eta'$$ and asymmetry parameters of $$Lambda_c^+ to Sigma^+ pi^0$$, $$Lambda_c^+ to Sigma^+ eta$$, and $$Lambda_c^+ to Sigma^+ eta'$$

Li, S. X.*; 谷田 聖; Belle Collaboration*; 他168名*

Physical Review D, 107(3), p.032003_1 - 032003_12, 2023/02

https://doi.org/10.1103/PhysRevD.107.032003
 被引用回数：6 パーセンタイル：53.22(Astronomy & Astrophysics)

We report a study of $$Lambda_c^+ to Sigma^+ pi^0$$, $$Lambda_c^+ to Sigma^+ eta$$, and $$Lambda_c^+ to Sigma^+ eta'$$ using the data sample corresponding to an integrated luminosity of 980 $$rm fb^{-1}$$ collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider. The branching fractions relative to $$Lambda_c^+ to Sigma^+ pi^0$$ are measured as: $$mathcal{B}_{Lambda_c^+ to Sigma^+ eta}/mathcal{B}_{Lambda_c^+ to Sigma^+ pi^0}=0.25 pm 0.03 pm 0.01$$ and $$mathcal{B}_{Lambda_c^+ to Sigma^+ eta'}/mathcal{B}_{Lambda_c^+ to Sigma^+ pi^0}=0.33 pm 0.06 pm 0.02$$. Using $$mathcal{B}_{Lambda_c^+ to Sigma^+ pi^0}=(1.25 pm 0.10)%$$, we obtain $$mathcal{B}_{Lambda_c^+ to Sigma^+ eta}=(3.14 pm 0.35 pm 0.11 pm 0.25)times10^{-3}$$ and $$mathcal{B}_{Lambda_c^+ to Sigma^+ eta'}=(4.16 pm 0.75 pm 0.21 pm 0.33)times10^{-3}$$. Here the uncertainties are statistical, systematic, and from $$mathcal{B}_{Lambda_c^+ to Sigma^+ pi^0}$$, respectively. The ratio of the branching fraction of $$Lambda_c^+ to Sigma^+ eta'$$ with respect to that of $$Lambda_c^+ to Sigma^+ eta$$ is measured to be $$mathcal{B}_{Lambda_c^+ to Sigma^+ eta'}/mathcal{B}_{Lambda_c^+ to Sigma^+ eta}=1.34 pm 0.28 pm 0.06$$. We update the asymmetry parameter of $$Lambda_c^+ to Sigma^+ pi^0$$, $$alpha_{Sigma^+ pi^0} = -0.48 pm 0.02 pm 0.02$$, with a considerably improved precision. The asymmetry parameters of $$Lambda_c^+ to Sigma^+ eta$$ and $$Lambda_c^+ to Sigma^+ eta'$$ are measured to be $$alpha_{Sigma^+ eta} = -0.99 pm 0.03 pm 0.05$$ and $$alpha_{Sigma^+ eta'} = -0.46 pm 0.06 pm 0.03$$ for the first time.

論文

Measurement of the $$B^+/B^0$$ production ratio in $$e^+e^-$$ collisions at the $$Upsilon(4S)$$ resonance using $$B rightarrow J/psi(ellell) K$$ decays at Belle

Choudhury, S.*; 谷田 聖; Belle Collaboration*; 他198名*

Physical Review D, 107(3), p.L031102_1 - L031102_6, 2023/02

https://doi.org/10.1103/PhysRevD.107.L031102
 被引用回数：14 パーセンタイル：78.14(Astronomy & Astrophysics)

We measure the ratio of branching fractions for the $$Upsilon (4S)$$ decays to $$B^+B^-$$ and $$B^0bar{B}{}^0$$ using $$B^+ rightarrow J/psi(ellell) K^+$$ and $$B^0 rightarrow J/psi(ellell) K^0$$ samples, where $$J/psi(ellell)$$ stands for $$J/psi to ell^+ell^-$$ ($$ell = e$$ or $$mu$$), with $$711$$ fb$$^{-1}$$ of data collected at the $$Upsilon(4S)$$ resonance with the Belle detector. We find the decay rate ratio of $$Upsilon(4S) rightarrow B^+B^-$$ over $$Upsilon(4S) rightarrow B^0bar{B}{}^0$$ to be $$1.065pm0.012pm 0.019 pm 0.047$$, which is the most precise measurement to date. The first and second uncertainties are statistical and systematic, respectively, and the third uncertainty is systematic due to the assumption of isospin symmetry in $$B to J/psi(ellell) K$$.

論文

Measurement of the branching fractions for Cabibbo-suppressed decays $$D^{+}to K^{+} K^{-}pi^{+}pi^{0}$$ and $$D_{(s)}^{+}to K^{+}pi^{-}pi^{+}pi^{0}$$ at Belle

Li, L. K.*; 谷田 聖; Belle Collaboration*; 他197名*

Physical Review D, 107(3), p.033003_1 - 033003_9, 2023/02

https://doi.org/10.1103/PhysRevD.107.033003
 被引用回数：0 パーセンタイル：0.00(Astronomy & Astrophysics)

We present measurements of the branching fractions for the singly Cabibbo-suppressed decays $$D^+to K^{+}K^{-}pi^{+}pi^{0}$$ and $$D_s^{+}to K^{+}pi^{-}pi^{+}pi^{0}$$, and the doubly Cabibbo-suppressed decay $$D^{+}to K^{+}pi^{-}pi^{+}pi^{0}$$, based on 980 $${rm fb}^{-1}$$ of data recorded by the Belle experiment at the KEKB $$e^{+}e^{-}$$ collider. We measure these modes relative to the Cabibbo-favored modes $$D^{+}to K^{-}pi^{+}pi^{+}pi^{0}$$ and $$D_s^{+}to K^{+}K^{-}pi^{+}pi^{0}$$. Our results for the ratios of branching fractions are $$B(D^{+}to K^{+}K^{-}pi^{+}pi^{0})/B(D^{+}to K^{-}pi^{+}pi^{+}pi^{0}) = (11.32 pm 0.13 pm 0.26)%$$, $$B(D^{+}to K^{+}pi^{-}pi^{+}pi^{0})/B(D^{+}to K^{-}pi^{+}pi^{+}pi^{0}) = (1.68 pm 0.11pm 0.03)%$$, and $$B(D_s^{+}to K^{+}pi^{-}pi^{+}pi^{0})/B(D_s^{+}to K^{+}K^{-}pi^{+}pi^{0}) = (17.13 pm 0.62 pm 0.51)%$$, where the uncertainties are statistical and systematic, respectively. The second value corresponds to $$(5.83pm 0.42)timestan^4theta_C$$, where $$theta_C$$ is the Cabibbo angle; this value is larger than other measured ratios of branching fractions for a doubly Cabibbo-suppressed charm decay to a Cabibbo-favored decay. Multiplying these results by world average values for $$B(D^{+}to K^{-}pi^{+}pi^{+}pi^{0})$$ and $$B(D_s^{+}to K^{+}K^{-}pi^{+}pi^{0})$$ yields $$B(D^{+}to K^{+}K^{-}pi^{+}pi^{0})= (7.08pm 0.08pm 0.16pm 0.20)times10^{-3}$$, $$B(D^{+}to K^{+}pi^{-}pi^{+}pi^{0})= (1.05pm 0.07pm 0.02pm 0.03)times10^{-3}$$, and $$B(D_s^{+}to K^{+}pi^{-}pi^{+}pi^{0}) = (9.44pm 0.34pm 0.28pm 0.32)times10^{-3}$$, where the third uncertainty is due to the branching fraction of the normalization mode. The first two results are consistent with, but more precise than, the current world averages. The last result is the first measurement of this branching fraction.

論文

Measurement of the $$Omega_c^0$$ lifetime at Belle II

Abudin$'e$n, F.*; 谷田 聖; Belle II Collaboration*; 他354名*

Physical Review D, 107(3), p.L031103_1 - L031103_7, 2023/02

https://doi.org/10.1103/PhysRevD.107.L031103
 被引用回数：6 パーセンタイル：53.22(Astronomy & Astrophysics)

We report on a measurement of the $$Omega_c^0$$ lifetime using $$Omega_c^0 to Omega^-pi^+$$ decays reconstructed in $$e^+e^-to cbar{c}$$ data collected by the Belle II experiment and corresponding to $$207~{rm fb^{-1}}$$ of integrated luminosity. The result, $$rmtau(Omega_c^0)=243pm48(stat)pm11(syst)~fs$$, agrees with recent measurements indicating that the $$Omega_c^0$$ is not the shortest-lived weakly decaying charmed baryon.

論文

Search for a dark photon and an invisible dark Higgs boson in $$mu^+mu^-$$ and missing energy final states with the Belle II experiment

Abudin$'e$n, F.*; 谷田 聖; Belle II Collaboration*; 他355名*

Physical Review Letters, 130(7), p.071804_1 - 071804_8, 2023/02

https://doi.org/10.1103/PhysRevLett.130.071804
 被引用回数：10 パーセンタイル：73.47(Physics, Multidisciplinary)

The dark photon $$A^prime$$ and the dark Higgs boson $$h^prime$$ are hypothetical particles predicted in many dark sector models. We search for the simultaneous production of $$A^prime$$ and $$h^prime$$ in the dark Higgsstrahlung process $$e^{+}e^{-}rightarrow A^prime , h^prime$$ with $$A^prime rightarrow mu^+mu^-$$ and $$ h^prime$$ invisible in electron-positron collisions at a center-of-mass energy of 10.58 GeV collected by the Belle II experiment in 2019. With an integrated luminosity of 8.34 fb$$^{-1}$$, we observe no evidence for signal. We obtain exclusion limits at 90% Bayesian credibility in the range of 1.7-5.0 fb on the cross section and in the range of $$1.7 times10^{-8}$$-$$200 times10^{-8}$$ on the effective coupling $$varepsilon^2 times alpha_D$$ for the $$A^prime$$ mass in the range of 4.0 GeV/$$c^2$$ $$< M_{A^prime}< 9.7$$ GeV/$$c^2$$ and for the $$h^prime$$ mass $$M_{h^prime} < M_{A^prime}$$, where $$varepsilon$$ is the mixing strength between the standard model and the dark photon and $$alpha_D$$ is the coupling of the dark photon to the dark Higgs boson. Our limits are the first in this mass range.

論文

Measurement of two-photon decay width of $$chi_{c2}(1P)$$ in $$ gamma gamma rightarrow chi_{c2}(1P) rightarrow J/psigamma$$ at Belle

清野 義敬*; 谷田 聖; Belle Collaboration*; 他194名*

Journal of High Energy Physics (Internet), 2023(1), p.160_1 - 160_18, 2023/01

https://doi.org/10.1007/JHEP01(2023)160
 被引用回数：0 パーセンタイル：0.00(Physics, Particles & Fields)

We report the measurement of the two-photon decay width of $$chi_{c2}(1P)$$ in two-photon processes at the Belle experiment. We analyze the process $$ gamma gamma rightarrow chi_{c2}(1P) rightarrow J/psigamma$$, $$J/psi rightarrow ell^{+} ell^{-}$$ $$(ell = e {rm or} mu)$$ using a data sample of 971 fb$$^{-1}$$ collected with the Belle detector at the KEKB $$e^{+} e^{-}$$ collider. In this analysis, the product of the two-photon decay width of $$chi_{c2}(1P)$$ and the branching fraction is determined to be $$Gamma_{gamma gamma}(chi_{c2}(1P)) mathcal{B}( chi_{c2}(1P) rightarrow J/psi , gamma )mathcal{B}(J/psi rightarrow ell^+ell^-) = {rm 14.8}$$ $$pm$$ $${rm 0.3}({rm stat.})$$ $$pm$$ $${rm 0.7}({rm syst.})$$ eV, which corresponds to $$ Gamma_{gamma gamma}(chi_{c2}(1P)) $$ = 653 $$pm$$ 13(stat.) $$pm$$ 31(syst.) $$pm$$ 17(B.R.) eV, where the third uncertainty is from $$mathcal{B}(chi_{c2}(1P) rightarrow J/psi , gamma)$$ and $$mathcal{B}(J/psi rightarrow ell^+ell^-)$$.

論文

Evidence for the singly Cabibbo-suppressed decay $$Omega^0_ctoXi^-pi^+$$ and search for $$Omega^0_ctoXi^-K^+$$ and $$Omega^-K^+$$ decays at Belle

Han, X.*; 谷田 聖; Belle Collaboration*; 他170名*

Journal of High Energy Physics (Internet), 2023(1), p.55_1 - 55_12, 2023/01

https://doi.org/10.1007/JHEP01(2023)055
 被引用回数：8 パーセンタイル：62.69(Physics, Particles & Fields)

Using a data sample of 980 fb$$^{-1}$$ collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider, we study for the first time the singly Cabibbo-suppressed decays $$Omega^0_ctoXi^{-}pi^{+}$$ and $$Omega^-K^+$$ and the doubly Cabibbo-suppressed decay $$Omega^0_cto Xi^- K^{+}$$. Evidence for an $$Omega^0_c$$ signal in the $$Omega^0_ctoXi^-pi^+$$ mode is reported with a significance of $$4.5sigma$$ including systematic uncertainties. The ratio of branching fractions to the normalization mode $$Omega_c^0to Omega^-pi^+$$ is measured to be $${cal B}(Omega_{c}^{0} to Xi^{-} pi ^{+} )/{cal B}(Omega_c^0to Omega^-pi^+)=0.253pm 0.053({rm stat.})pm 0.030({rm syst.}).$$ No significant signals of $$Omega^0_ctoXi^-K^+$$ and $$Omega^-K^+$$ modes are found. The upper limits at $$90%$$ confidence level on ratios of branching fractions are determined to be $${cal B}(Omega_{c}^{0} to Xi^{-} K ^{+})/{cal B}(Omega_c^0to Omega^-pi^+) < 0.070$$ and $${cal B}(Omega_{c}^{0} to Omega^{-}K^{+})/{cal B}(Omega_c^0to Omega^-pi^+) < 0.29.$$

論文

Measurements of the branching fractions $$mathcal{B} (bar{B}{}^0 to D^{*+} pi^-)$$ and $$mathcal{B} (bar{B}{}^0 to D^{*+} K^-)$$ and tests of QCD factorization

Krohn, J.-F.*; 谷田 聖; Belle Collaboration*; 他198名*

Physical Review D, 107(1), p.012003_1 - 012003_12, 2023/01

https://doi.org/10.1103/PhysRevD.107.012003
 被引用回数：5 パーセンタイル：40.20(Astronomy & Astrophysics)

Using $$(771.6 pm 10.6) times 10^6$$ $$Bbar{B}$$ meson pairs recorded by the Belle experiment at the KEKB $$e^+ e^-$$ collider, we report the branching fractions $$mathcal{B}(bar{B}^0 to D^{*+} pi^-) = (2.62 pm 0.02 pm 0.09)times 10^{-3}$$ and $$mathcal{B}(bar{B}^0 to D^{*+} K^-) = (2.22 pm 0.06 pm 0.08)times 10^{-4}$$; the quoted uncertainties are statistical and systematic, respectively. A measurement of the ratio of these branching fractions is also presented, $$mathcal{R}_{K/pi}=mathcal{B}(bar{B} to D^{*+}K^-) /mathcal{B}(bar{B} to D^{*+}pi^-) = (8.41 pm 0.24 pm 0.13)times 10^{-2}$$, where systematic uncertainties due to the $$D^{*+}$$ meson reconstruction cancel out. Furthermore, we report a new QCD factorization test based on the measured ratios for $$bar{B} to D^{*+}h^-$$ and $$bar{B} to D^{*+}ell^-nu$$ decays at squared momentum transfer values equivalent to the mass of the $$h = pi$$ or $$K$$ hadron. The parameters $$|a_1(h)|$$ are measured to be $$|a_1(pi)|= 0.884 pm 0.004 pm 0.003 pm 0.016$$ and $$|a_1(K)|=0.913 pm 0.019 pm 0.008 pm 0.013$$, where the last uncertainties account for all external inputs. These values are approximately $$15%$$ lower than those expected from theoretical predictions. Subsequently, flavor $$SU(3)$$ symmetry is tested by measuring the ratios for pions and kaons, $$|a_1(K)|^2/ |a_1(pi)|^2=1.066 pm 0.042 pm 0.018 pm 0.023$$, as well as for different particle species. The ratio is consistent with unity and therefore no evidence for $$SU(3)$$ symmetry breaking effects is found at the $$5%$$ precision level.

論文

Study of $$e^{+}e^{-}toetaphi$$ via initial state radiation at Belle

Zhu, W. J.*; 谷田 聖; Belle Collaboration*; 他174名*

Physical Review D, 107(1), p.012006_1 - 012006_10, 2023/01

https://doi.org/10.1103/PhysRevD.107.012006
 被引用回数：3 パーセンタイル：22.30(Astronomy & Astrophysics)

Using $$980~fb^{-1}$$ of data collected on and around the $$Upsilon(nS)(n=1,2,3,4,5)$$ resonances with the Belle detector at the KEKB collider, we measure the cross section of $$e^{+}e^{-}to etaphi$$ from threshold to $$3.95~{rm GeV}/c^{2}$$ via initial-state radiation. From a multi-parameter fit assuming $$phi(2170)$$ exists in the $$etaphi$$ final state according to previous measurement by BESIII, the resonant parameters of $$phi(1680)$$ are determined to be $$m_{phi(1680)} = (1683 pm 7 pm 9)~{rm MeV}/c^{2}$$ (statistical and systematic errors, respectively), $$Gamma_{phi(1680)} = (149 pm 12 pm 13)~{rm MeV}$$ and, depending on the possible presence of interfering resonances, $$Gamma^{e^{+}e^{-}}_{phi(1680)}cdot {cal B}[phi(1680)toetaphi] = (122 pm 6 pm 13)~{rm eV}$$, $$(219 pm 15 pm 18)~{rm eV}$$, $$(163 pm 11 pm 13)~{rm eV}$$ or $$(203 pm 12 pm 18)~{rm eV}$$. The branching fraction of $$phi(1680)toetaphi$$ decay is determined to be approximately 20%. Additionally, the branching fraction for $$J/psitoetaphi$$ is measured to be $$(7.1pm 1.0 pm 0.5)times 10^{-4}$$. However, there is no significant observed $$phi(2170)$$ signal in the $$etaphi$$ final states in this analysis, and correspondingly the upper limit for $$Gamma^{e^{+}e^{-}}_{phi(2170)}cdot {cal B}(phi(2170)toetaphi)$$ is determined to be either $$0.17~{rm eV}$$ (for two fits), or $$18.6~{rm eV}$$ (remaining two fits), at 90% confidence level.

論文

Evidence of a new excited charmed baryon decaying to $$Sigma_{c}(2455)^{0,++} pi^{pm}$$

Li, Y. B.*; 谷田 聖; Belle Collaboration*; 他194名*

Physical Review Letters, 130(3), p.031901_1 - 031901_7, 2023/01

https://doi.org/10.1103/PhysRevLett.130.031901
 被引用回数：21 パーセンタイル：90.15(Physics, Multidisciplinary)

We present the study of $$bar{B}^{0} to Sigma_{c}(2455)^{0,++} pi^{pm} bar{p}$$ decays based on $$772times 10^{6}$$ $$Bbar{B}$$ events collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider. The $$Sigma_{c}(2455)^{0,++} $$ candidates are reconstructed via their decay to $$Lambda_{c}^{+} pi^{mp}$$ and $$Lambda_{c}^{+}$$ decays to $$pK^{-}pi^{+},~pK_{S}^{0},$$ and $$Lambdapi^{+}$$ final states. The corresponding branching fractions are measured to be $${cal B}(bar{B}^{0} to Sigma_{c}(2455)^{0} pi^{+} bar{p}) = (1.09 pm 0.06 pm 0.07)times10^{-4}$$ and $${cal B}(bar{B}^{0} to Sigma_{c}(2455)^{++} pi^{-} bar{p}) = (1.84pm 0.11 pm 0.12)times 10^{-4}$$, which are consistent with the world average values with improved precision. A new structure is found in the $$M_{Sigma_{c}(2455)^{0,++}pi^{pm}}$$ spectrum with a significance of $$4.2sigma$$ including systematic uncertainty. The structure is possibly an excited $$Lambda_{c}^{+}$$ and is tentatively named $$Lambda_{c}(2910)^{+}$$. Its mass and width are measured to be $$(2913.8 pm 5.6 pm 3.8)$$ MeV/$$c^{2}$$ and $$(51.8pm20.0 pm 18.8)$$ MeV, respectively. The products of branching fractions for the $$Lambda_{c}(2910)^{+}$$ are measured to be $${cal B}(bar{B}^{0} to Lambda_{c}(2910)^{+}bar{p})times{cal B}(Lambda_{c}(2910)^{+} to Sigma_{c}(2455)^{0}pi^{+}) = (9.5 pm 3.6 pm 1.6)times 10^{-6}$$ and $${cal B}(bar{B}^{0} to Lambda_{c} (2910)^{+}bar{p})times {cal B}(Lambda_{c}(2910)^{+} to Sigma_{c}(2455)^{++}pi^{-}) = (1.24 pm 0.35 pm 0.10)times 10^{-5}$$. Here, the first and second uncertainties are statistical and systematic, respectively.

論文

Search for the decay $$B_s^0 to eta^prime K_S^0$$

Pang, T.*; 谷田 聖; Belle Collaboration*; 他206名*

Physical Review D, 106(5), p.L051103_1 - L051103_8, 2022/09

https://doi.org/10.1103/PhysRevD.106.L051103
 被引用回数：1 パーセンタイル：0.00(Astronomy & Astrophysics)

We report the results of the first search for the decay $$B_s^0 to eta^prime K_S^0$$ using $$121.4,{rm fb}^{-1}$$ of data collected at the $$Upsilon(5S)$$ resonance with the Belle detector at the KEKB asymmetric-energy $$e^+ e^-$$ collider. We observe no signal and set a 90% confidence-level upper limit of $$8.16 times 10^{-6}$$ on the $$B_s^0 to eta^prime K_S^0$$ branching fraction.

論文

Search for $$Z^{'} rightarrow mu^{+} mu^{-}$$ in the $$L_mu {-} L_tau$$ gauge-symmetric model at Belle

Czank, T.*; 谷田 聖; Belle Collaboration*; 他209名*

Physical Review D, 106(1), p.012003_1 - 012003_10, 2022/07

https://doi.org/10.1103/PhysRevD.106.012003
 被引用回数：12 パーセンタイル：62.34(Astronomy & Astrophysics)

We search for a new gauge boson $$Z'$$ that couples only to heavy leptons and their corresponding neutrinos in the process $$e^{+} e^{-} rightarrow Z'(rightarrow mu^{+}mu^{-}) mu^{+}mu^{-}$$, using a 643 fb$$^{-1}$$ data sample collected by the Belle experiment at or near the $$Upsilon(1S,2S,3S,4S,5S)$$ resonances at the KEKB collider. For the first time, effects due to initial state radiation are used in estimating the detection efficiency. No signal is observed in the mass range of 0.212 $ - 10 GeV/${it c}^2$$ and we set an upper limit on the coupling strength, $$g'$$, constraining $$Z'$$ as a possible contributor to the anomalous magnetic dipole moment of muon.

論文

Search for the radiative penguin decays $$B^{0} to K_S^{0}K_S^{0}$$$$gamma$$ in the Belle experiment

Jeon, H. B.*; 谷田 聖; Belle Collaboration*; 他219名*

Physical Review D, 106(1), p.012006_1 - 012006_9, 2022/07

https://doi.org/10.1103/PhysRevD.106.012006
 被引用回数：1 パーセンタイル：0.00(Astronomy & Astrophysics)

We report the first search for the penguin-dominated process $$B^0 rightarrow K_S^0 K_S^0 gamma$$ using the full data sample of $$772times 10^6$$ $$Bbar{B}$$ pairs collected with the Belle detector at the KEKB asymmetric-energy $$e^+ e^-$$ collider. We do not observe any statistically significant signal yield in the $$K_S^0$$-pair invariant mass range 1 GeV/$$c^2 < M_{K_S^0 K_S^0} < $$ 3 GeV/$$c^2$$, and set the following upper limits at 90% confidence level: $$mathcal{B}(B^0 to K_S^0 K_S^0 gamma) < 5.8times10^{-7}$$, $$mathcal{B}(B^0 to f_2 gamma)times mathcal{B}(f_2 (1270) to K_S^0 K_S^0 ) < 3.1times10^{-7}$$, and $$mathcal{B}(B^0 to f_2^{prime} gamma)times mathcal{B}(f_2^{prime} (1525) to K_S^0 K_S^0 ) < 2.1times10^{-7}$$. Further, 90% confidence upper limits have also been set in the range of [0.7-2.9]$$times10^{-7}$$ on the $$B^0 rightarrow K_S^0 K_S^0 gamma$$ branching fraction in bins of $$M_{K_S^0 K_S^0}$$.

論文

Search for charged lepton flavor violating decays of $$Upsilon(1S)$$

Patra, S.*; 谷田 聖; Belle Collaboration*; 他216名*

Journal of High Energy Physics (Internet), 2022(5), p.95_1 - 95_17, 2022/05

https://doi.org/10.1007/JHEP05(2022)095
 被引用回数：9 パーセンタイル：55.55(Physics, Particles & Fields)

We present a search for the charged lepton-flavor-violating decays $$Upsilon(1S)rightarrowellell^prime$$ and radiative charged lepton-flavour-violating decays $$Upsilon(1S)rightarrowgammaellell^prime$$ [$$ell,ell^prime = e, mu, tau$$] using the 158 million $$Upsilon(2S)$$ sample collected by the Belle detector at the KEKB collider. This search uses $$Upsilon(1S)$$ mesons produced in $$pi^+pi^-Upsilon(1S)$$ transitions. We do not find any significant signal, so we provide upper limits on the branching fractions at the 90% confidence level.

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