Ratio Of Branching Fractions Research Articles

Measurement of the ratio of branching fractions mathcal{B}left({B}_c^{+}to {B}_s^0{pi}^{+}right)/mathcal{B}left({B}_c^{+}to J/psi {pi}^{+}right)

The ratio of branching fractions of {B}_c^{+}to {B}_s^0{pi}^{+} and {B}_c^{+}to J/psi {pi}^{+} decays is measured with proton-proton collision data of a centre-of-mass energy of 13 TeV. The data were collected with the LHCb experiment during 2016–2018, corresponding to an integrated luminosity of 5.4 fb−1. The {B}_s^0 mesons are reconstructed via the decays {B}_s^0to J/psi phi and {B}_s^0to {D}_s^{-}{pi}^{+} . The ratio of branching fractions is measured to be mathcal{B}left({B}_c^{+}to {B}_s^0{pi}^{+}right)/mathcal{B}left({B}_c^{+}to J/psi {pi}^{+}right)=91pm 10pm 8pm 3 where the first uncertainty is statistical, the second is systematic and the third is due to the knowledge of the branching fractions of the intermediate state decays.

Weak decays of antitriplet charmed baryons from the perspective of flavor symmetry

In this work, we carry out a global fit for the two-body weak decays of antitriplet charmed baryons in both SU(3) respected and broken scenarios incorporating all the available data up to date. In the SU(3) irreducible representation approach (IRA), more amplitudes for irreducible representation terms are taken into account and the ranges for their coefficients in each scenarios are predicted. By a comparison among various fitting schemes in this work, experimental data prefer the SU(3) symmetry breaking scenario. Observables of interest, branching fractions and decay asymmetries of all the Cabibbo-favored (CF), singly Cabibbo-suppressed (SCS) and doubly Cabibbo-suppressed (DCS) channels are calculated in the chosen fitting scheme. Most of our predictions are consistent well with experimental data. We further propose more ways to explore the SU(3) symmetry in charmed baryon decays: (i) A clear measurement of branching fraction on CF mode {Xi}_c^0to {Xi}^0{pi}^0 as a large difference exists between SU(3) respected and broken scenarios. (ii) The decay asymmetries of the five yet-to-be measured CF decay modes, {Xi}_c^0to {Lambda}^0{K}_S , Σ0KS, Ξ0π0, Ξ0η, Ξ0η′, for their opposite signs in the two different cases. (iii) The future measurement on branching fraction ratios indicated from eq. (2.10) and presented on table 7. An improved measurement for alpha left({Lambda}_c^{+}to p{K}_Sright) is called for since predictions from both fittings, including the one in current work and earlier works, and the pole model calculation prefer an opposite sign from previous experimental value. Given branching fractions of most of the CF modes and part of the SCS modes being measured, predictions for the remaining channels, including the DCS modes as well as more decay asymmetries, are anticipated to be checked by the upcoming experiments in BESIII, Belle/Belle-II and LHCb.

Measurement of the branching fraction of Ξc0→Λc+π− at Belle

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 Ξc0→Λc+π− with Λc+ reconstructed via its pK−π+ decay mode. The branching fraction ratio B(Ξc0→Λc+π−)/B(Ξc0→Ξ−π+) is measured to be 0.38±0.04±0.04. Combining with the world average value of B(Ξc0→Ξ−π+), the branching fraction B(Ξc0→Λc+π−) is deduced to be (0.54±0.05±0.05±0.12)%. Here, the uncertainties above are statistical, systematic, and from B(Ξc0→Ξ−π+), respectively.Received 17 June 2022Accepted 28 July 2022DOI:https://doi.org/10.1103/PhysRevD.107.032005Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Physical SystemsCharmed baryonsGeneral Physics

Measurement of the branching fractions for Cabibbo-suppressed decays D+→K+K−π+π0 and D(s)+→K+π−π+π0 at Belle

We present measurements of the branching fractions for the singly Cabibbo-suppressed decays D+→K+K−π+π0 and Ds+→K+π−π+π0, and the doubly Cabibbo-suppressed decay D+→K+π−π+π0, based on 980 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+→K−π+π+π0 and Ds+→K+K−π+π0. Our results for the ratios of branching fractions are B(D+→K+K−π+π0)/B(D+→K−π+π+π0)=(11.32±0.13±0.26)%, B(D+→K+π−π+π0)/B(D+→K−π+π+π0)=(1.68±0.11±0.03)%, and B(Ds+→K+π−π+π0)/B(Ds+→K+K−π+π0)=(17.13±0.62±0.51)%, where the uncertainties are statistical and systematic, respectively. The second value corresponds to (5.83±0.42)×tan4θC, where θC 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+→K−π+π+π0) and B(Ds+→K+K−π+π0) yields B(D+→K+K−π+π0)=(7.08±0.08±0.16±0.20)×10−3, B(D+→K+π−π+π0)=(1.05±0.07±0.02±0.03)×10−3, and B(Ds+→K+π−π+π0)=(9.44±0.34±0.28±0.32)×10−3, 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.Received 3 May 2022Accepted 28 September 2022DOI:https://doi.org/10.1103/PhysRevD.107.033003Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasElectroweak interactionPhysical SystemsCharmed mesonsTechniquesParticle decaysParticles & Fields

First search for the weak radiative decays Λc+→Σ+γ and Ξc0→Ξ0γ

We present the first search for the weak radiative decays Λc+→Σ+γ and Ξc0→Ξ0γ 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 Λc+→Σ+γ or Ξc0→Ξ0γ signals. Taking the decays Λc+→pK−π+ and Ξc0→Ξ−π+ as normalization channels, the upper limits at 90% credibility level on the ratios of branching fractions B(Λc+→Σ+γ)/B(Λc+→pK−π+)<4.0×10−3 and B(Ξc0→Ξ0γ)/B(Ξc0→Ξ−π+)<1.2×10−2 are determined. We obtain the upper limits at 90% credibility level on the absolute branching fractions B(Λc+→Σ+γ)<2.6×10−4 and B(Ξc0→Ξ0γ)<1.8×10−4.Received 27 June 2022Accepted 2 August 2022DOI:https://doi.org/10.1103/PhysRevD.107.032001Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBranching fractionElectroweak radiative correctionsPhysical SystemsCharmed baryonsParticles & Fields

Understanding the nature of Ω(2012) in a coupled-channel approach

We perform a systematic analysis of the mass and strong decays of the $\mathrm{\ensuremath{\Omega}}(2012)$ resonance in a coupled-channel approach of a bare three-quark state and a composite meson-baryon state. Besides the coupling of the bare state and ${\mathrm{\ensuremath{\Xi}}}^{*}\overline{K}$ channel, the effective meson-baryon interactions are also included. We find a pole with a mass of 2008 MeV by solving the Bethe-Salpeter equation. The calculated decay widths and its ratios of branching fractions ${\mathcal{R}}_{\mathrm{\ensuremath{\Xi}}\overline{K}}^{\mathrm{\ensuremath{\Xi}}\ensuremath{\pi}\overline{K}}$ agree well with the new experimental measurement by the Belle Collaboration. Our results suggest that both three-quark core and ${\mathrm{\ensuremath{\Xi}}}^{*}\overline{K}$ channel are essential for the description of the $\mathrm{\ensuremath{\Omega}}(2012)$ resonance. We expect that present calculations can help us to better understand the nature of $\mathrm{\ensuremath{\Omega}}(2012)$ resonance.

Evidence for the singly Cabibbo-suppressed decay {Omega}_c^0to {Xi}^{-}{pi}^{+} and search for {Omega}_c^0to {Xi}^{-}{K}^{+} and Ω−K+ decays at Belle

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}_c^0to {Xi}^{-}{pi}^{+} and Ω−K+ and the doubly Cabibbo-suppressed decay {Omega}_c^0to {Xi}^{-}{K}^{+} . Evidence for an {Omega}_c^0 signal in the {Omega}_c^0 → Ξ−π+ mode is reported with a significance of 4.5σ including systematic uncertainties. The ratio of branching fractions to the normalization mode {Omega}_c^0 → Ω−π+ is measured to beBΩc0→Ξ−π+/BΩc0→Ω−π+=0.253±0.052stat.±0.030syst..\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{B}\\left({\\Omega}_c^0\ o {\\Xi}^{-}{\\pi}^{+}\\right)/\\mathcal{B}\\left({\\Omega}_c^0\ o {\\Omega}^{-}{\\pi}^{+}\\right)=0.253\\pm 0.052\\left(\ extrm{stat}.\\right)\\pm 0.030\\left(\ extrm{syst}.\\right). $$\\end{document}No significant signals of {Omega}_c^0to {Xi}^{-}{K}^{+} and Ω−K+ modes are found. The upper limits at 90% confidence level on ratios of branching fractions are determined to beBΩc0→Ξ−K+/BΩc0→Ω−π+<0.070\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{B}\\left({\\Omega}_c^0\ o {\\Xi}^{-}{K}^{+}\\right)/\\mathcal{B}\\left({\\Omega}_c^0\ o {\\Omega}^{-}{\\pi}^{+}\\right)<0.070 $$\\end{document}andBΩc0→Ω−K+/BΩc0→Ω−π+<0.29.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{B}\\left({\\Omega}_c^0\ o {\\Omega}^{-}{K}^{+}\\right)/\\mathcal{B}\\left({\\Omega}_c^0\ o {\\Omega}^{-}{\\pi}^{+}\\right)<0.29. $$\\end{document}

$$B_c$$ meson spectroscopy motivated by general features of pNRQCD

In the present article the mass spectrum, decay constant, weak decay widths, life time and branching fraction ratios and electromagnetic transition widths are calculated for ground and radially excited $B_c$ meson. To calculate the above properties the Schr\"{o}dinger equation has been solved numerically for the potential. The potential employed consists of relativistic correction in the framework of pNRQCD, added to the Cornell potential. The calculated results are compared with available experimental and theoretical results.

Effects from hadronic structure of photon on and decays* *Supported in part by the Open Project of Shaanxi Collaborative Innovation Center of Industrial Auxiliary Chemistry & Technology (XTKF-2020-01), the National Science Foundation of China (11705159, 11975195), the Natural Science Foundation of Shandong province (ZR2019JQ04, ZR2022ZD26, ZR2020MA093) and the Project of Shandong Province Higher Educational Science and Technology Program (2019KJJ007)

Using the perturbative QCD approach, we studied the effects of the hadronic structure of photons on the pure annihilation rediative decays and . These decays have small branching fractions due to the power suppression by , which makes them very sensitive to next-leading power corrections. The quark components and the related two-particle distribution amplitudes of a final state photon are introduced. The branching fractions can be enhanced remarkably by factorizable and nonfactorizable emission diagrams. The branching fraction of increases by approximately 40 times, and those of and are on the order of . We also note that the ratio of branching fractions of and is very sensitive to the effects of the hadronic structure of photons. All these results can be tested in future.

Phenomenology analysis of bar{B}^* rightarrow V tau ^-bar{nu }_{tau } decays in and beyond the Standard Model

Motivated by the persistent anomalies reported in the brightarrow c tau bar{nu } data, we investigate the semileptonic decays bar{B}^* rightarrow V tau ^-bar{nu }_{tau } (V=D^*_{u,d,s},J/psi ), within the Standard Model and beyond. The relevant transition form factors, being calculated in the covariant light-front quark model, is the main source of theoretical uncertainties. Using various best-fit solutions for the new operator Wilson coefficients, we report numerical results on various observables related to the processes bar{B}^* rightarrow V tau ^-bar{nu }_{tau }, such as the branching ratios, the ratio of branching fractions, the hadron and lepton polarization asymmetries, the forward–backward asymmetries and the convexity parameter. We also predict the q^2 distribution of these observables both within the Standard Model and in various new physics scenarios. The accessible observables are studied in order to assess their sensitivity to the different new physics scenarios. We can find that some of the new physics scenarios can be differentiated from each other by using these observables and their correlations. We also find that some observables of these decay modes are sizeable and deviate significantly (for new physics coupling parameter S_R especially) from their corresponding standard model values, which are expected to be within the reach of Run III of Large Hadron Collider experiment. And experimental information on these distributions which will be testified in the future can help to disentangle the dynamical origin of the current anomalies.

Exclusive semileptonic B_c-meson decays to radially excited charmonium and charm meson states

In the wake of recent measurements of ratios of semileptonic branching fractions: {mathscr {R}}_{J/psi }, {mathscr {R}}_D and {mathscr {R}}_{D^{*}} reported by the LHCb, BELLE and HFLAV Collaborations, we calculate invariant form factors for the exclusive semileptonic B_c-meson decays to radially excited charmonium and charm meson states in the full kinematical region within the framework of relativistic independent quark (RIQ) model. We evaluate the lepton mass effect in the decay processes induced by brightarrow c,u transition at the quark level. Our predictions on branching fractions for B_crightarrow eta _c/psi (nS) are found sim 10^{-2}-10^{-4} and that for B_crightarrow D^{*}(nS) are sim 10^{-4} in their e^{-} decay modes, which lie within the detection accuracy of current experiment. Our predictions on branching fractions, forward backward asymmetry and asymmetry parameter are found in reasonable agreement with other model predictions; which can hopefully be tested in future experiments at LHC and Tevatron. Our predicted observable {mathscr {R}} in this sector are found comparable to other standard model (SM) predictions that violate the lepton flavor universality hinting at new physics beyond SM.

W -exchange contribution to the decays Ξcc++→Ξc+(′)π+ using light-cone sum rules

We calculate the W-exchange contribution to the $\Xi_{cc}^{++}\to\Xi_{c}^{+(\prime)}\pi^{+}$ decay using light-cone sum rules. The two-particle light-cone distribution amplitudes of the pion are used as non-perturbative input for the sum rules calculation, and the perturbative kernel is calculated at the leading order. We obtain the corresponding decay branching fractions by combining our W-exchange amplitudes with the factorizable amplitudes given by various theoretical methods from the literature. It is shown that with the factorizable amplitudes from heavy quark effective theory, we obtain the branching fraction ratio ${\cal B}(\Xi_{cc}^{++}\to\Xi_{c}^{+\prime}\pi^{+})/{\cal B}(\Xi_{cc}^{++}\to\Xi_{c}^{+}\pi^{+})= 1.42\pm 0.78$, which is consistent with the experimental value of $1.41\pm 0.17\pm 0.1$.

Testing the molecular nature of φ(2170)

In this talk we show our recent results on the decay widths of φ(2170) to final states formed by an anti-Kaon and a Kaonic resonance, in particular, K(1460), K1(1270) and K1(1400), considering a molecular description for φ(2170). Branching fraction ratios are obtained and compared with the recent results found by the BESIII collaboration, finding compatible results.

Observation of the Singly Cabibbo Suppressed Decay Λ_{c}^{+}→nπ^{+}.

The singly Cabibbo-suppressed decay Λ_{c}^{+}→nπ^{+} is observed for the first time with a statistical significance of 7.3σ by using 3.9 fb^{-1} of e^{+}e^{-} collision data collected at center-of-mass energies between 4.612 and 4.699GeV with the BESIII detector at BEPCII. The branching fraction of Λ_{c}^{+}→nπ^{+} is measured to be (6.6±1.2_{stat}±0.4_{syst})×10^{-4}. By taking the upper limit of branching fractions of Λ_{c}^{+}→pπ^{0} from the Belle experiment, the ratio of branching fractions between Λ_{c}^{+}→nπ^{+} and Λ_{c}^{+}→pπ^{0} is calculated to be larger than 7.2 at the 90% confidence level, which disagrees with most predictions of the available phenomenological models. In addition, the branching fractions of the Cabibbo-favored decays Λ_{c}^{+}→Λπ^{+} and Λ_{c}^{+}→Σ^{0}π^{+} are measured to be (1.31±0.08_{stat}±0.05_{syst})×10^{-2} and (1.22±0.08_{stat}±0.07_{syst})×10^{-2}, respectively, which are consistent with previous results.

Observation of {Lambda}_b^0 → D+pπ−π− and {Lambda}_b^0 → D*+pπ−π− decays

The multihadron decays {Lambda}_b^0 → D+pπ−π− and {Lambda}_b^0 → D*+pπ−π− are observed in data corresponding to an integrated luminosity of 3 fb−1, collected in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV by the LHCb detector. Using the decay {Lambda}_b^0 → {Lambda}_c^{+} π+π−π− as a normalisation channel, the ratio of branching fractions is measured to beBΛb0→D+pπ−π−BΛb0→Λc0π+π−π−×BD+→K−π+π+BΛc0→pK−π−=5.35±0.21±0.16%,\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\frac{\\mathcal{B}\\left({\\Lambda}_b^0\ o {D}^{+}p{\\pi}^{-}{\\pi}^{-}\\right)}{\\mathcal{B}\\left({\\Lambda}_b^0\ o {\\Lambda}_c^0{\\pi}^{+}{\\pi}^{-}{\\pi}^{-}\\right)}\ imes \\frac{\\mathcal{B}\\left({D}^{+}\ o {K}^{-}{\\pi}^{+}{\\pi}^{+}\\right)}{\\mathcal{B}\\left({\\Lambda}_c^0\ o {pK}^{-}{\\pi}^{-}\\right)}=\\left(5.35\\pm 0.21\\pm 0.16\\right)\\%, $$\\end{document}where the first uncertainty is statistical and the second systematic. The ratio of branching fractions for the {Lambda}_b^0 → D*+pπ−π− and {Lambda}_b^0 → D+pπ−π− decays is found to beBΛb0→D∗+pπ−π−BΛb0→D+pπ−π−×BD∗+→D+π0+BD∗+→D+γ=61.3±4.3±4.0%.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\frac{\\mathcal{B}\\left({\\Lambda}_b^0\ o {D}^{\\ast +}p{\\pi}^{-}{\\pi}^{-}\\right)}{\\mathcal{B}\\left({\\Lambda}_b^0\ o {D}^{+}p{\\pi}^{-}{\\pi}^{-}\\right)}\ imes \\left(\\mathcal{B}\\left({D}^{\\ast +}\ o {D}^{+}{\\pi}^0\\right)+\\mathcal{B}\\left({D}^{\\ast +}\ o {D}^{+}\\gamma \\right)\\right)=\\left(61.3\\pm 4.3\\pm 4.0\\right)\\%. $$\\end{document}

Study of {mathrm{B}}_{mathrm{c}}^{+} decays to charmonia and three light hadrons

Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb−1 collected with the LHCb detector, seven decay modes of the {mathrm{B}}_{mathrm{c}}^{+} meson into a J/ψ or ψ(2S) meson and three charged hadrons, kaons or pions, are studied. The decays {mathrm{B}}_{mathrm{c}}^{+} → (ψ(2S) → J/ψπ+π−)π+, {mathrm{B}}_{mathrm{c}}^{+} → ψ(2S)π+π−π+, {mathrm{B}}_{mathrm{c}}^{+} → J/ψK+π−π+ and {mathrm{B}}_{mathrm{c}}^{+} → J/ψK+K−K+ are observed for the first time, and evidence for the {mathrm{B}}_{mathrm{c}}^{+} → ψ(2S)K+K−π+, decay is found, where J/ψ and ψ(2S) mesons are reconstructed in their dimuon decay modes. The ratios of branching fractions between the different {mathrm{B}}_{mathrm{c}}^{+} decays are reported as well as the fractions of the decays proceeding via intermediate resonances. The results largely support the factorisation approach used for a theoretical description of the studied decays.

Observation of the suppressed Λb0→DpK− decay with D→K+π− and measurement of its CP asymmetry

A study of $\Lambda_b^0$ baryon decays to the $DpK^-$ final state is presented based on a proton-proton collision data sample corresponding to an integrated luminosity of 9 fb$^{-1}$ collected with the LHCb detector. Two $\Lambda_b^0$ decays are considered, $\Lambda_b^0\to DpK^-$ with $D\to K^-\pi^+$ and $D\to K^+\pi^-$, where $D$ represents a superposition of $D^0$ and $\overline{D}^0$ states. The latter process is expected to be suppressed relative to the former, and is observed for the first time. The ratio of branching fractions of the two decays is measured, and the $C\!P$ asymmetry of the suppressed mode, which is sensitive to the CKM angle $\gamma$, is also reported.

Search for the doubly charmed baryon {varXi}_{cc}^{+} in the {varXi}_c^{+}{pi}^{-}{pi}^{+} final state

A search for the doubly charmed baryon {varXi}_{cc}^{+} is performed in the {varXi}_c^{+}{pi}^{-}{pi}^{+} invariant-mass spectrum, where the {varXi}_c^{+} baryon is reconstructed in the pK−π+ final state. The study uses proton-proton collision data collected with the LHCb detector at a centre- of-mass energy of 13 TeV, corresponding to a total integrated luminosity of 5.4 fb−1. No significant signal is observed in the invariant-mass range of 3.4–3.8 GeV/c2. Upper limits are set on the ratio of branching fractions multiplied by the production cross-section with respect to the {varXi}_{cc}^{++} → ( {varXi}_c^{+} → pK−π+)π+ decay for different {varXi}_{cc}^{+} mass and lifetime hypotheses in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 2.5 to 25 GeV/c. The results from this search are combined with a previously published search for the {varXi}_{cc}^{+} → {varLambda}_c^{+} K−π+ decay mode, yielding a maximum local significance of 4.0 standard deviations around the mass of 3620 MeV/c2, including systematic uncertainties. Taking into account the look-elsewhere effect in the 3.5–3.7 GeV/c2 mass window, the combined global significance is 2.9 standard deviations including systematic uncertainties.

Study of electroweak penguin B decays at Belle II experiment

The electroweak b → sll (l = e, µ) transition is a flavor-changing neutral current process that mediates through a one-loop penguin diagram. The decay is considered to be a good probe for the New Physics as particles predicted in the beyond Standard Model theories can enter into the loop. The exclusive decay B → K (*) l + l − was first observed by the Belle experiment and it provides many observables such as the branching fraction, CP asymmetry, forward-backward asymmetry, and other angular observables. Recently, the LHCb experiment has reported some clue of a lepton flavor universality violation from the branching fraction ratio of the B → Kµ + µ − and B → Ke + e − decays. In this presentation, we report the status of the B → Kl + l − decay analysis at the Belle II experiment which started the data taking in 2019. We also, present an activity at the Belle II Chulalongkorn University group where we study the B → KJ/ψ decay which has the same topology as the B → Kl + l − .

Observation of the decay D0→ρ−μ+νμ

By analyzing an e+e− annihilation data sample corresponding to an integrated luminosity of 2.93 fb−1 collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, we measure the branching fraction of the D0→ρ−μ+νμ decay for the first time. We obtain BD0→ρ−μ+νμ=(1.35±0.09stat±0.09syst)×10−3. Using the world average of BD0→ρ−e+νe, we find a branching fraction ratio of BD0→ρ−μ+νμ/BD0→ρ−e+νe=0.90±0.11, which agrees with the theoretical expectation of lepton flavor universality within the uncertainty. Combining the world average of BD+→ρ0μ+νμ and the lifetimes of D0(+), we obtain a partial decay width ratio of ΓD0→ρ−μ+νμ/(2ΓD+→ρ0μ+νμ)=0.71±0.14, which is consistent with the isospin symmetry expectation of unity within 2.1σ. For the reported values of BD0→ρ−μ+νμ/BD0→ρ−e+νe and ΓD0→ρ−μ+νμ/2ΓD+→ρ0μ+νμ, the uncertainty is the quadratic sum of the statistical and systematic uncertainties.Received 3 June 2021Accepted 26 October 2021DOI:https://doi.org/10.1103/PhysRevD.104.L091103Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBranching fractionLeptonic, semileptonic & radiative decaysParticle interactionsQuark mixingPhysical SystemsCharmed mesonsPropertiesFlavor symmetriesForm factorsTechniquesLepton collidersParticles & Fields