Measurement Of Branching Fraction Research Articles

Branching fractions of B^-rightarrow D^-X_{0,1}(2900) and their implications

The exotic states X_{0,1}(2900) with the quark flavor of csbar{u}bar{d} are recently observed in the mass spectrum of D^+K^- in B^-rightarrow D^-D^+K^- by the LHCb collaboration. To explore the nature of X_{0,1}(2900), except for analyzing their masses and decay widths as usually did in literatures, the study of their production mechanism in B-meson weak decays would provide another important information. The amplitude of B^-rightarrow D^- X_{0,1} is non-factorizable. We consider the final-state-interaction effects and calculate them via the rescattering mechanism. The measured branching fractions of B^-rightarrow D^- X_{0,1} are revealed. It is manifested by {B}^-rightarrow Lambda _c^-Xi _c^{(prime )0} and Lambda _b^0rightarrow P_c^+K^- that the rescattering mechanism can result in the relatively large branching fractions. The similar processes of B^-rightarrow pi ^-X_{0,1} are also analyzed. The isospins of X_{0,1} can be investigated by Brightarrow DX_{0,1}^{pm ,0} decays.

Measurement of the relative branching fractions of B+→h+h′+h′− decays

The relative branching fractions of $B^+ \to h^+h^{\prime +}h^{\prime -}$ decays, where $h^{(\prime)}$ is a pion or kaon, are measured. The analysis is performed with a data sample, collected with the LHCb detector, corresponding to an integrated luminosity of $3.0 {\rm fb}^{-1}$ of $pp$ collisions. The results obtained improve significantly on previous measurements of these quantities, and are important for the interpretation of Dalitz plot analyses of three-body charmless hadronic decays of $B^+$ mesons.

Semileptonic decay of [formula omitted] via neutral meson mixing

Based on the mechanism of neutral meson mixing, we predict the branching fraction of the semileptonic decay of Ds+→π0ℓ+νℓ (ℓ=e, μ) using recently measured branching fraction of Ds+→ηe+νe by BESIII experiment. We also give a formula that can describe the neutral meson mixing of π0, η, η′ and a pseudoscalar gluonium G in a unified way. The predicted branching fraction of Ds+→π0e+νe decay is B(Ds+→π0e+νe)=(2.65±0.38)×10−5. It is important to search for the decay Ds+→π0ℓ+νℓ in experiment, in order to understand the mechanism of π0 production in Ds+→π0 transition in semileptonic decay. We also estimate the branching fraction of Ds+→π0τ+ντ, which is the only kinematically allowed semi-tauonic decay mode of the charmed meson, since the mass value of Ds+ meson is just slightly above the threshold of π0τ+ generation in the semi-tauonic decay.

Measurement of the absolute branching fraction of the inclusive decay Lambda _c^+ rightarrow K_S^0X

We report the first measurement of the absolute branching fraction of the inclusive decay Lambda _c^+ rightarrow K_S^0X. The analysis is performed using an e^+e^- collision data sample corresponding to an integrated luminosity of 567 hbox {pb}^{-1} taken at sqrt{s} = 4.6 GeV with the BESIII detector. Using eleven Cabibbo-favored {bar{Lambda }}_c^- decay modes and the double-tag technique, this absolute branching fraction is measured to be {mathcal {B}}(Lambda _c^+ rightarrow K_S^0X)=(9.9pm 0.6pm 0.4)%, where the first uncertainty is statistical and the second systematic. The relative deviation between the branching fractions for the inclusive decay and the observed exclusive decays is (18.7pm 8.3)%, which indicates that there may be some unobserved decay modes with a neutron or excited baryons in the final state.

Charm Physics at BESIII

Recently, BESIII has performed many analyses with the largest e+ e- annihilation data set taken on the mass-thresholds. Those works focus on the measurements of the CKM matrix elements |Vcd(s)|, the transition form factors , tests of lepton flavor universality, precise measurements of branching fraction, studies of interesting intermediate states in the multiple-body decays, and searchs for the new physics. Among those, we present the results with three categorities, the (semi-) leptonic decays, hadronic decays, and the rare decays.

Initial charm program on direct measurements of weak decay constant fDs and branching fraction B(Ds → μνμ) and prospect with high-precision

First direct measurements of the weak decay constant [Formula: see text] and the [Formula: see text] branching fractions to [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] at the BES experiments in 1990s are reviewed. Referring to the BESIII results of [Formula: see text] and branching fraction [Formula: see text] with best precision1 to date, prospect for challenge on precision measurements of [Formula: see text] and [Formula: see text] at BESIII is presented.

Measurements of Absolute Branching Fractions of Fourteen Exclusive Hadronic D Decays to η.

Using 2.93 fb^{-1} of e^{+}e^{-} collision data taken at a center-of-mass energy of 3.773GeV with the BESIII detector, we report the first measurements of the absolute branching fractions of 14 hadronic D^{0(+)} decays to exclusive final states with an η, e.g., D^{0}→K^{-}π^{+}η, K_{S}^{0}π^{0}η, K^{+}K^{-}η, K_{S}^{0}K_{S}^{0}η, K^{-}π^{+}π^{0}η, K_{S}^{0}π^{+}π^{-}η, K_{S}^{0}π^{0}π^{0}η, and π^{+}π^{-}π^{0}η; D^{+}→K_{S}^{0}π^{+}η, K_{S}^{0}K^{+}η, K^{-}π^{+}π^{+}η, K_{S}^{0}π^{+}π^{0}η, π^{+}π^{+}π^{-}η, and π^{+}π^{0}π^{0}η. Among these decays, the D^{0}→K^{-}π^{+}η and D^{+}→K_{S}^{0}π^{+}η decays have the largest branching fractions, which are B(D^{0}→K^{-}π^{+}η)=(1.853±0.025_{stat}±0.031_{syst})% and B(D^{+}→K_{S}^{0}π^{+}η)=(1.309±0.037_{stat}±0.031_{syst})%, respectively. The charge-parity asymmetries for the six decays with highest event yields are determined, and no statistically significant charge-parity violation is found.

Direct CP violation in internal W-emission dominated baryonic B decays

The observation of CP violation has been experimentally verified in numerous B decays but is yet to be confirmed in final states with half-spin particles. We focus our attention on baryonic B-meson decays mediated dominantly through internal W-emission processes and show that they are promising processes to observe for the first time the CP violating effects in B decays to final states with half-spin particles. Specifically, we study the bar{B}^0rightarrow pbar{p}pi ^0(rho ^0) and bar{B}^0rightarrow pbar{p}pi ^+pi ^- decays. We obtain mathcal{B}(bar{B}^0rightarrow pbar{p}pi ^0)=(5.0pm 2.1)times 10^{-7}, in agreement with current data, and mathcal{B}(bar{B}^0rightarrow pbar{p}rho ^0)simeq mathcal{B}(bar{B}^0rightarrow pbar{p}pi ^0)/3. Furthermore, we find mathcal{A}_{CP}(bar{B}^0rightarrow pbar{p}pi ^0,pbar{p}rho ^0,pbar{p}pi ^+pi ^-) =(-16.8pm 5.4,-12.6pm 3.0,-11.4pm 1.9)%. With measured branching fractions mathcal{B}(bar{B}^0rightarrow pbar{p}pi ^0,pbar{p}pi ^+pi ^-)sim mathcal{O}(10^{-6}), we point out that mathcal{A}_{CP}sim -(10-20)% can be new observables for CP violation, accessible to the Belle II and/or LHCb experiments.

Measurements of experimental transition probabilities of 3p54p → 3p54s arrays in neutral argon.

We have determined the absolute transition probabilities of 27 emission lines of neutral argon originating from the 3p54p→3p54s transition array in the wavelength region from 650 to 1100 nm using an argon-filled hollow cathode discharge lamp. The absolute transition probabilities have been deduced using the lifetimes of the upper levels and the measured branching fractions. Atomic oscillator strengths and relative line strengths for all the transitions have been computed using calculated transition probabilities. The experimentally determined transition probabilities are found to be in good agreement with that calculated in the intermediate coupling (IC) scheme. The comparison of experimentally determined transition probabilities with reported theoretical transition probabilities confirms that the IC scheme for the lower as well as for the upper levels seems to be a useful scheme for the level designation for the 3p54p to 3p54s configuration-based levels in argon. Furthermore, the measured relative line strengths are used to validate the J-file sum rule for the 3p54p→3p54s transition array of argon. The reported transition probabilities, oscillator strengths, and relative line strengths are compared with the published data, showing good agreement.

Measurements of branching fractions, absolute transition probabilities and J-file sum rule for the 4p55p→4p55s transitions array in neutral krypton

We present new results of transition rates for twenty two electric dipole transitions of neutral krypton associated with the 4p55p→4p55 s configurations-based levels covering the wavelength region from 500 to 1000 nm using a krypton filled hollow cathode discharge lamp coupled with a set of four miniature spectrometers. The branching fractions of various dipole allowed transitions were extracted using the observed line intensity ratios, whereas, the absolute values of the transition probabilities were deduced from the measured branching fractions in combination with the known lifetimes of the upper levels. The experimental data are in good agreement with that calculated in the intermediate angular momentum coupling scheme. In addition, line strengths for all the transitions have been extracted using the measured transition probabilities. The J-file sum rule was also tested for each level attached to the 4p55p→4p55 s configurations based on the recently measured and calculated normalized multiplet strengths.

Combined measurements of Higgs boson production and decay using up to 80 fb−1 of proton-proton collision data at s=13 TeV collected with the ATLAS experiment

Combined measurements of Higgs boson production cross sections and branching fractions are presented. The combination is based on the analyses of the Higgs boson decay modes $H \to \gamma\gamma$, $ZZ^\ast$, $WW^\ast$, $\tau\tau$, $b\bar{b}$, $\mu\mu$, searches for decays into invisible final states, and on measurements of off-shell Higgs boson production. Up to $79.8$ fb$^{-1}$ of proton-proton collision data collected at $\sqrt{s}=$ 13 TeV with the ATLAS detector are used. Results are presented for the gluon-gluon fusion and vector-boson fusion processes, and for associated production with vector bosons or top-quarks. The global signal strength is determined to be $\mu = 1.11^{+0.09}_{-0.08}$. The combined measurement yields an observed (expected) significance for the vector-boson fusion production process of $6.5\sigma$ ($5.3\sigma$). Measurements in kinematic regions defined within the simplified template cross section framework are also shown. The results are interpreted in terms of modifiers applied to the Standard Model couplings of the Higgs boson to other particles, and are used to set exclusion limits on parameters in two-Higgs-doublet models and in the simplified Minimal Supersymmetric Standard Model. No significant deviations from Standard Model predictions are observed.

Measurements of decay branching fractions of in associated production at the CEPC * * Supported by the National Key Program for S&T Research and Development (2016YFA0400400), National Natural Science Foundation of China (NSFC) (11705028), Fundamental Research Funds for the Central Universities (2242015K40027 and 2242017K40018), Provincial Innovation and Entrepreneurship Training Program for Undergraduate (201710286068X), and Beijing Municipal Science and Technology Commission

The high-precision measurement of Higgs boson properties is one of the primary goals of the Circular Electron Positron Collider (CEPC). The measurements of decay branching fraction in the CEPC experiment is presented, considering a scenario of analysing 5000 fb-1 collision data with the center-of-mass energy of 250 GeV. In this study the Higgs bosons are produced in association with a pair of leptons, dominantly mediated by the ZH production process. The statistical uncertainty of the signal cross section is estimated to be about 1% in the final state, and approximately 5%-10% in the final states. In addition, the main sources of the systematic uncertainties and their impacts to the measurements of branching fractions are discussed. This study demonstrates the potential of precise measurement of the hadronic final states of the Higgs boson decay at the CEPC, and will provide key information to understand the Yukawa couplings between the Higgs boson and quarks, which are predicted to be the origin of quarks’ masses in the standard model.

Model-independent investigation of the RJ/ψ,ηc and ratios of decay widths of semileptonic Bc decays into a P-wave charmonium

Experimental measurements of decay branching fractions of semitaunic and semimuonic [Formula: see text] into [Formula: see text] have challenged the lepton flavor universality in standard models with about two standard deviations. In this paper, we first investigate the unitary constraint on form factors of [Formula: see text] meson into [Formula: see text]-wave and [Formula: see text]-wave charmonium. Such constraint leads to the exploration of the [Formula: see text] and other ratios [Formula: see text], [Formula: see text], and [Formula: see text] in a model-independent way. These results together with future experimental measurements can be used to explore the lepton flavor universality in a more systematic way. In addition, we point out that the helicity-dependent ratios [Formula: see text] and [Formula: see text] can also provide complementary information.

Search for direct production of the f1(1285) resonance in e+e− collisions

A search for direct production of the f1(1285) resonance in e+e− annihilation is performed with the SND detector at the VEPP-2000 e+e− collider. The analysis is based on data with an integrated luminosity of 15.1 pb−1 accumulated in the center-of-mass energy range 1.2–1.4 GeV. Two e+e−→f1(1285) candidate events are found at the peak of the resonance and zero events beyond the resonance. The significance of the e+e−→f1(1285) signal is 2.5σ. The cross section at the maximum of the resonance is found to be σ(e+e−→f1)=45−24+33 pb. The corresponding branching fraction B(f1(1285)→e+e−)=(5.1−2.7+3.7)×10−9. We consider this result as a first indication of the process e+e−→f1(1285). The measured branching fraction is consistent with the theoretical prediction.

Measurement of the electron reconstruction efficiency at LHCb

The single electron track-reconstruction efficiency is calibrated using a sample corresponding to 1.3 fb−1 of pp collision data recorded with the LHCb detector in 2017. This measurement exploits B+→ J/ψ(e+e−)K+ decays, where one of the electrons is fully reconstructed and paired with the kaon, while the other electron is reconstructed using only the information of the vertex detector. Despite this partial reconstruction, kinematic and geometric constraints allow the B meson mass to be reconstructed and the signal to be well separated from backgrounds. This in turn allows the electron reconstruction efficiency to be measured by matching the partial track segment found in the vertex detector to tracks found by LHCb's regular reconstruction algorithms. The agreement between data and simulation is evaluated, and corrections are derived for simulated electrons in bins of kinematics. These correction factors allow LHCb to measure branching fractions involving single electrons with a systematic uncertainty below 1%.

Observation of τ−→π−ντe+e− and search for τ−→π−ντμ+μ−

We present the first measurements of branching fractions of rare tau-lepton decays, $\tau^- \rightarrow \pi^- \nu_{\tau} \ell^+ \ell^-$ ($\ell = e$ or $\mu$), using a data sample corresponding to 562 fb$^{-1}$ collected at a center-of-mass energy of 10.58 GeV with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The $\tau^- \rightarrow \pi^- \nu_\tau e^+ e^-$ decay is observed for the first time with 7.0$\sigma$ significance. The partial branching fraction determined by the structure-dependent mechanisms mediated by either a vector or an axial-vector current for the mass region $M_{\pi e e}>1.05$ GeV/$c^2$ is measured to be $\mathcal{B}(\tau^-\rightarrow \pi^- \nu_\tau e^+ e^-)[M_{\pi^- e^+ e^-}>1.05~{\rm GeV}/c^2] = (5.90 \pm 0.53 \pm 0.85 \pm 0.11) \times 10^{-6}$, where the first uncertainty is statistical, the second is systematic, and the third is due to the model dependence. In the full phase space, due to the different detection efficiencies for the structure-dependent mechanisms mediated by axial-vector and vector currents, the branching fraction varies from $\mathcal{B}_{A}(\tau^-\rightarrow \pi^- \nu_\tau e^+ e^-) = (1.46 \pm 0.13 \pm 0.21) \times 10^{-5}$ to $\mathcal{B}_{V}(\tau^-\rightarrow \pi^- \nu_\tau e^+ e^-) = (3.01 \pm 0.27 \pm 0.43) \times 10^{-5}$, respectively. An upper limit is set on the branching fraction of the $\tau^- \rightarrow \pi^- \nu_\tau \mu^+ \mu^-$ decay, $\mathcal{B}(\tau^-\rightarrow \pi^- \nu_\tau \mu^+ \mu^-) < 1.14 \times 10^{-5}$, at the 90% confidence level.

Measurement of branching fractions for D meson decaying into ϕ meson and a pseudoscalar meson

The four decay modes D0→ϕπ0, D0→ϕη, D+→ϕπ+, and D+→ϕK+ are studied by using a data sample taken at the centre-of-mass energy s=3.773 GeV with the BESIII detector, corresponding to an integrated luminosity of 2.93 fb−1. The branching fractions of the first three decay modes are measured to be B(D0→ϕπ0)=(1.168±0.028±0.028)×10−3, B(D0→ϕη)=(1.81±0.46±0.06)×10−4, and B(D+→ϕπ+)=(5.70±0.05±0.13)×10−3, respectively, where the first uncertainties are statistical and the second are systematic. In addition, the upper limit of the branching fraction for D+→ϕK+ is given to be 2.1×10−5 at the 90% confidence level. The ratio of B(D0→ϕπ0) to B(D+→ϕπ+) is calculated to be (20.49±0.50±0.45)%, which is consistent with the theoretical prediction based on isospin symmetry between these two decay modes.

Extraction of form Factors from a Four-Dimensional Angular Analysis of B[over ¯]→D^{*}ℓ^{-}ν[over ¯]_{ℓ}.

An angular analysis of the decay B[over ¯]→D^{*}ℓ^{-}ν[over ¯]_{ℓ}, ℓ∈{e,μ}, is reported using the full e^{+}e^{-} collision data set collected by the BABAR experiment at the ϒ(4S) resonance. One B meson from the ϒ(4S)→BB[over ¯] decay is fully reconstructed in a hadronic decay mode, which constrains the kinematics and provides a determination of the neutrino momentum vector. The kinematics of the semileptonic decay is described by the dilepton mass squared, q^{2}, and three angles. The first unbinned fit to the full four-dimensional decay rate in the standard model is performed in the so-called Boyd-Grinstein-Lebed approach, which employs a generic q^{2} parametrization of the underlying form factors based on crossing symmetry, analyticity, and QCD dispersion relations for the amplitudes. A fit using the more model-dependent Caprini-Lellouch-Neubert (CLN) approach is performed as well. Our form factor shapes show deviations from previous fits based on the CLN parametrization. The latest form factors also provide an updated prediction for the branching fraction ratio R(D^{*})≡B(B[over ¯]→D^{*}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]→D^{*}ℓ^{-}ν[over ¯]_{ℓ})=0.253±0.005. Finally, using the well-measured branching fraction for the B[over ¯]→D^{*}ℓ^{-}ν[over ¯]_{ℓ} decay, a value of |V_{cb}|=(38.36±0.90)×10^{-3} is obtained that is consistent with the current world average for exclusive B[over ¯]→D^{(*)}ℓ^{-}ν[over ¯]_{ℓ} decays and remains in tension with the determination from inclusive semileptonic B decays to final states with charm.

Partial-wave analysis of J/ψ→K+K−π0

A partial-wave analysis of the decay $J/\psi \to K^+K^-\pi^0$ has been made using $(223.7\pm1.4)\times 10^{6}$ $J/\psi$ events collected with the BESIII detector in 2009. The analysis, which is performed within the isobar-model approach, reveals contributions from $K^*_2(1430)^\pm$, $K^*_2(1980)^\pm$ and $K^*_4(2045)^\pm$ decaying to $K^\pm\pi^0$. The two latter states are observed in $J/\psi$ decays for the first time. Two resonance signals decaying to $K^+K^-$ are also observed. These contributions can not be reliably identified and their possible interpretations are discussed. The measured branching fraction $B(J/\psi \to K^+K^-\pi^0)$ of $(2.88\pm0.01\pm0.12)\times10^{-3}$ is more precise than previous results. Branching fractions for the reported contributions are presented as well. The results of the partial-wave analysis differ significantly from those previously obtained by BESII and BABAR.

First measurements of absolute branching fractions of the Ξc+ baryon at Belle

We present the first measurements of the absolute branching fractions of $\Xi_c^+$ decays into $\Xi^- \pi^+ \pi^+$ and $p K^- \pi^+$ final states. Our analysis is based on a data set of $(772\pm 11)\times 10^{6}$ $B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB $e^+e^-$ collider. We measure the absolute branching fraction of $\bar{B}^{0} \to \bar{\Lambda}_{c}^{-} \Xi_{c}^{+}$ with the $\Xi_c^+$ recoiling against $\bar{\Lambda}_c^-$ in $\bar{B}^0$ decays resulting in ${\cal B}(\bar{B}^{0} \to \bar{\Lambda}_{c}^{-} \Xi_{c}^{+}) = [1.16 \pm 0.42(\rm stat.) \pm 0.15(\rm syst.)] \times 10^{-3}$. We then measure the product branching fractions ${\cal B}(\bar{B}^{0} \to \bar{\Lambda}_c^- \Xi_c^+){\cal B}(\Xi_c^+ \to \Xi^- \pi^+ \pi^+)$ and ${\cal B}(\bar{B}^{0} \to \bar{\Lambda}_c^- \Xi_c^+){\cal B}(\Xi_c^+ \to p K^- \pi^+)$. Dividing these product branching fractions by $\bar{B}^{0} \to \bar{\Lambda}_{c}^{-} \Xi_{c}^{+}$ yields: ${\cal B}(\Xi_c^+ \to \Xi^- \pi^+ \pi^+) = [2.86 \pm 1.21(\rm stat.) \pm 0.38(\rm syst.)]\%$ and ${\cal B}(\Xi_c^+ \to p K^- \pi^+)=[0.45 \pm 0.21(\rm stat.) \pm 0.07(\rm syst.)]\%$. Our result for ${\cal B}(\Xi_c^+ \to \Xi^- \pi^+ \pi^+)$ can be combined with $\Xi_c^+$ branching fractions measured relative to $\Xi_c^+ \to \Xi^- \pi^+ \pi^+$ to set the absolute scale for many $\Xi_c^+$ branching fractions.