Study of the semileptonic decay Ds+ -> f0(980) e+ nu and implications for Bs -> J/psi f0

Measurement of the lifetime of the B_c meson in the semileptonic decay channel

Using approximately 1.3 fb-1 of data collected by the D0 detector between 2002 and 2006, we measure the lifetime of the B_c meson in the B_c -> J/psi mu nu X final state. A simultaneous unbinned likelihood fit to the J/ψ+mu invariant mass and lifetime distributions yields a signal of 881 +/- 80 (stat) candidates and a lifetime measurement of τ(B_c) = 0.448 +0.038 -0.036 (stat) +/- 0.032 (syst) ps.

A study of time-dependent CP-violating asymmetries in B0 -> J/psi K0S and B0 -> psi(2S) K0S decays

We present a preliminary measurement of time-dependent CP-violating asymmetries in B0 -> J/psi K0S and B0 -> psi(2S) K0S decays recorded by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The data sample consists of 9.0 fb-1 collected at the Y(4S) resonance and 0.8 fb-1 off-resonance. One of the neutral B mesons, produced in pairs at the Y(4S), is fully reconstructed. The flavor of the other neutral B meson is tagged at the time of its decay, mainly with the charge of identified leptons and kaons. A neural network tagging algorithm is used to recover events without a clea…

Absolute Branching Fraction Measurements for D^+ and D^0 Inclusive Semileptonic Decays

We present measurements of the inclusive branching fractions for the decays D^+ -> X e^+ nu_e and D^0 -> X e^+ nu_e, using 281 pb^-1 of data collected on the psi(3770) resonance with the CLEO-c detector. We find Br(D^0 ->Xe^+ν_e) = (6.46 \pm 0.17 \pm 0.13)% and Br((D^+ -> Xe^+nu_e) = (16.13 \pm 0.20 \pm 0.33)%. Using the known D meson lifetimes, we obtain the ratio Gamma{D^+}^sl/Gamma_{D^0}^sl= 0.985\pm 0.028\pm 0.015, confirming isospin invariance at the level of 3%. The positron momentum spectra from D^+ and D^0 have consistent shapes.

Measurement of the Lambda^0_b lifetime in the decay Lambda^0_b -> J/psi Lambda^0 with the D0 Detector

We present measurements of the Lambda^0_b lifetime in the exclusive decay channel Lambda^0_{b}->J/psi Lambda^0, with J/psi to mu+ mu- and Lambda^0 to p pi-, the B^0 lifetime in the decay B^0 -> J/psi K^0_S with J/psi to mu+ mu- and K^0_S to pi+ pi-, and the ratio of these lifetimes. The analysis is based on approximately 250 pb^{-1} of data recorded with the D0 detector in pp(bar) collisions at sqrt{s}=1.96 TeV. The Lambda^0_b lifetime is determined to be tau(Lambda^0_b) = 1.22 +0.22/-0.18 (stat) +/- 0.04 (syst) ps, the B^0 lifetime tau(B^0) = 1.40 +0.11/-0.10 (stat) +/- 0.03 (syst) ps, and th…

Charm Semileptonic Decays at CLEO-c

We review the recent results on D and Ds meson semileptonic decays from CLEO-c. Comparisons with lattice quantum chromodynamics (LQCD) calculations and implications for B physics are also discussed.

Study of D0 --> pi- e+ nu(e), D+ --> pi0 e+ nu(e), D0 --> K- e+ nu(e), and D+ --> anti-K0 e+ nu(e) in Tagged Decays of the psi(3770) Resonance

Using psi(3770) --> DDbar events collected with the CLEO-c detector at the Cornell e+ e- storage ring, tagged by fully reconstructing one D meson in a hadronic decay mode, we measure absolute branching fractions and differential decay rates for D0 --> pi- e+ nu(e), D+ --> pi0 e+ nu(e), D0 --> K- e+ nu(e), and D+ --> anti-K0 e+ nu(e). The measured decay rates are used to study semileptonic form factors governing these transitions and to test unquenched Lattice QCD (LQCD) calculations. We average our results with previously published CLEO-c measurements of the same quantities using a neutrino re…

Recent Results on Charm Semileptonic Decays

We review the recent results on D and D_s meson semileptonic decays from CLEO-c, BABAR, and Belle. Comparisons with lattice quantum chromodynamics (LQCD) calculations and implications for B physics are also discussed.

A Study of the Semileptonic Charm Decays D^0 --> pi^- e^+ nu_e, D^+ --> pi^0 e^+ nu_e, D^0 --> K^- e^+ nu_e, and D^+ --> barK^0 e^+ nu_e

Using a sample of 1.8 million DDbar meson pairs collected at the psi(3770) with the CLEO-c detector, we study the semileptonic decays D^0 -> pi^- e^+ nu_e, D^+ -> pi^0 e^+ ν_e, D^0 -> K^- e^+ ν_e, and D^+ -> Kbar^0 e^+ nu_e. For the total branching fractions we find B(D^0 -> pi^- e^+ ν_e) = 0.299(11)(9)%, B(D^+ -> pi^0 e^+ ν_e) = 0.373(22)(13)%, B(D^0 -> K^- e^+ nu_e) = 3.56(3)(9)%, and B(D^+ -> Kbar^0 e^+ nu_e) = 8.53(13)(23)%, where the first error is statistical and the second systematic. In addition, form factors are studied through fits to the partial branching fractions obtained in five …

First CP Violation Results from BABAR

We present a preliminary measurement of time-dependent CP-violating asymmetries in B^0-->J/psi K_S and B^0-->psi(2S) K_S decays recorded by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. The data sample consists of 9.0 fb-1 collected at the Upsilon(4S) resonance and 0.8 fb-1 off-resonance. One of the neutral B mesons, produced in pairs at the Upsilon(4S), is fully reconstructed. The flavor of the other neutral B meson is tagged at the time of its decay, mainly with the charge of identified leptons and kaons. The time difference between the decays is determined by measuring the …

Measurement of B_c properties at CDF

The Bc meson is composed of two heavy quarks of distinct flavor. Measurements of its lifetime and production properties have been made based on semileptonic Bc to J/psi+l+X decays using data collected with the CDF II detector corresponding to an integrated luminosity of 1 fb-1. The Bc average lifetime ctau is measured to be 142.5+15.8-14.8(stat) 5.5(syst) mum. The measurements of the ratio of the production cross section times branching ratio of Bc to J/psi+mu+nu relative to B+ to J/psi+K were done for two pT(B) thresholds: for pT(B) greater 4 GeV/c as 0.295+/-0.040(stat)+0.033-0.026(syst.)0.0…

Open Charm Physics at CLEO-c

Recent CLEO-c results on open charm physics at the psi(3770) are presented. Measurements of hadronic and semileptonic branching fractions of the D0 and D+ mesons are discussed as well as the leptonic decay D+ to mu+ nu_mu and determination of the D meson decay constant.

D0D0bar Quantum Correlations, Mixing, and Strong Phases

Due to the presence of the quantum correlation between the pair-produced D0 and D0bar from the decay of the psi(3770), the time-integrated single and double tag decay rates depend on charm mixing amplitudes, doubly-Cabibbo-suppressed amplitudes, and the relative strong phase, delta, between D0 and D0bar decays to identical final states. Using 281 pb^-1 of integrated luminosity collected with the CLEO-c detector on the psi(3770) resonance, we measure the absolute branching fractions of D0 decays to K-pi+, CP eigenstates, and semileptonic final states to determine cos(delta) for K-pi+ and to lim…

Ratios of bottom meson branching fractions involving J/psi mesons and determination of b quark fragmentation fractions

We report a measurement of the ratios of the decay rates of the B^+, B^0 and B^0_s mesons into exclusive final states containing a J/psi meson. The final states were selected from 19.6 pb^{-1} of p-pbar collisions recorded by the Collider Detector at Fermilab. These data are interpreted to determine the bquark fragmentation fractions f_u, f_d and f_s. We also determine the branching fractions for the decay modes B^+ --> J/psi K^+, B^+ --> J/psi K^*(892)^+, B^0 --> J/psi K^0, B^0 --> J/psi K^*(892)^0 and B_s^0 --> J/psi phi(1020). We discuss the implications of these measurements to B meson dec…

Renormalization group improved implications of semileptonic operators in SMEFT

We study implications of the four-fermion semileptonic operators at the low-energy and at electroweak (EW) scale in the framework of Standard Model Effective Field Theory (SMEFT). We show how the renormalization group (RG) running effects can play an important role in probing the \emph{generic flavour structure} of such operators. It is shown that at the 1-loop level, through RG running, depending upon the flavour structure, these operators can give rise to sizable effects at low energy in the electroweak precision (EWP) observables, the leptonic, quark, as well as the $Z$ boson flavour violat…

The \boldmath$B\to D^\ast\ellν$ semileptonic decay at nonzero recoil and its implications for $\ |V_{cb}\ |$ and $R(D^\ast)$

We present nearly final results from our analysis of the form factors for $B\to D^\ast\ellν$ decay at nonzero recoil. Our analysis includes 15 MILC asqtad ensembles with $N_f=2+1$ flavors of sea quarks and lattice spacings ranging from $a\approx0.15$ fm down to $0.045$ fm. The valence light quarks employ the asqtad action, whereas the $b$ and $c$ quarks are treated using the Fermilab action. We discuss the impact that our results will have on $\ |V_{cb}\ |$ and $R(D^\ast)$.

D0barD0 Quantum Correlations, Mixing, and Strong Phases

Due to the quantum correlation between the pair-produced D0 and D0bar from the decay of the psi(3770), the time-integrated single and double tag decay rates depend on charm mixing amplitudes, doubly-Cabibbo-suppressed amplitudes, and the relative strong phase delta between D0 and D0bar decays to identical final states. Using 281 pb^{-1} collected with the CLEO-c detector on the psi(3770) resonance, we measure the absolute branching fractions of D0 decays to hadronic flavored states, CP eigenstates, and semileptonic final states to determine the relative strong phase, cos delta, of the K- pi+ f…

Implications of the CP asymmetry in semileptonic B decay

Recent experimental searches for $A_{SL}$, the CP asymmetry in semileptonic B decay, have reached an accuracy of order one percent. Consequently, they give meaningful constraints on new physics. We find that cancellations between the Standard Model (SM) and new physics contributions to $B^0 - \bar B^0$ mixing cannot be as strong as was allowed prior to these measurements. The predictions for this asymmetry within the SM and within models of minimal flavor violation (MFV) are below the reach of present and near future measurements. Including order $m_c^2/m_b^2$ and $Λ_{QCD}/m_b$ corrections we …

Observation of B_c Mesons in p-bar p Collisions at sqrt{s} = 1.8 TeV

We report the observation of bottom-charmed mesons B_c in 1.8 TeV p-bar p collisions using the CDF detector at the Fermilab Tevatron. The B_c mesons were found through their semileptonic decays, B_c -> J/psi lepton X. A fit to the J/psi lepton mass distribution yielded 20.4 +6.2 -5.5 events from B_c mesons. A test of the null hypothesis, i.e. an attempt to fit the data with background alone, was rejected at the level of 4.8 standard deviations. By studying the quality of the fit as a function of the assumed B_c mass, we determined M(B_c) = 6.40 +- 0.39 +- 0.13 GeV/c^2. From the distribution of…

Hadronic and rare B decays with the BaBar and Belle experiments

We review recent experimental results on Bd and Bs mesons decays by the BaBar and Belle experiments. These include measurements of the color-suppressed decays B0bar to D(*)0h0, h0=pi0, eta, etaprime, omega, observation of the baryonic decay B0bar to Lambdac+ Lambdabar K-, measurements of the charmless decays B to eta h, h=K, pi, B to Kpi and observation of CP eigenstates in the Bs decays: B0s to J/psi f0(980), B0s to J/psi f0(1370) and B0s to J/psi eta. The theoretical implications of these results will be considered.

Constraints on the form factors for K --> pi l nu and implications for V_us

Rigorous bounds are established for the expansion coefficients governing the shape of semileptonic K-->pi form factors. The constraints enforced by experimental data from tau-->K pi nu eliminate uncertainties associated with model parameterizations in the determination of |V_us|. The results support the validity of a powerful expansion that can be applied to other semileptonic transitions.

Recent Results From CLEO-c

This paper describes recent preliminary results from the CLEO-c experiment using an initial ~60 pb^-1 sample of data collected in e^+e^- collisions at a center of mass energy around the mass of the psi(3770). A first measurement of the branching fraction BR(D^+ -> mu^+ nu) = (3.5 +/- 1.4 +/- 0.6)x 10^-4 and the corresponding decay constant f_D = (202 +/- 41 +/- 17) MeV has been made. Several charged and neutral D meson absolute exclusive semileptonic branching fractions have been measured, including first measurements of the branching fractions BR(D^0 -> rho^-e^+ nu) = (0.19 +/- 0.04 +/- 0.02)…

Inclusive semileptonic fits, heavy quark masses, and V_cb

We perform global fits to the moments of semileptonic B decay distributions and extract |V_cb|, the heavy quark masses, and the non-perturbative parameters of the heavy quark expansion. We include NNLO perturbative corrections and recent determinations of the charm mass, and discuss how they improve the precision of the global fit. In particular, using the m_c determination of Ref.[11] we get m_b^kin=4.541(23) GeV and |V_cb|=(42.42+- 0.86) 10^{-3}. We also discuss the implications of the new fits for the normalization of rare B decays, the zero-recoil sum rule in B-> D* l nu, and the inclusive…

Study of methods of resolved top quark reconstruction in semileptonic $t\bar{t}$ decay

Study of methods of resolved top quarks kinematic reconstruction in the $t\bar{t} \rightarrow \ell+$jets channel is presented at the particle level as well as the fast-simulation detector level. Previous and current pseudo-top quark reconstruction algorithms are compared with suggestions presented on how to improve the reconstructed top-quark mass line shape, including the check of performance on physics observables in terms of correlations between detector, particle and parton levels, and in unfolding, with implications for current high energy physics experiments.

Combined D0 Measurements Constraining the CP-violating Phase and Width Difference in the $B_s^0$ System

We combine the D0 measurement of the width difference between the light and heavy B_s^0 mass eigenstates and of the CP-violating mixing phase determined from the time-dependent angular distributions in the B_s -> J/psi phi decays along with the charge asymmetry in semileptonic decays also measured with the D0 detector. With the additional constraint from the world average of the flavor-specific B_s^0 lifetime, we obtain Delta Gamma_s = (Γ_L - Γ_H) = 0.13 +- 0.09 ps$^{-1}$ and phi_s = -0.70 ^{+0.47}_{-0.39}. The data sample corresponds to an integrated luminosity of 1.1 fb^{-1} accumulated with…

Recent Bes Results on psi(3770) and D Meson Production and Decay

Using a data sample of 17.7 $\rm pb^{-1}$ collected at 3.773 GeV with the BES-II detector at the BEPC, the cross sections for $D^0 \bar D^{0}$ and $D^+D^-$ productions at 3.773 GeV have been measured. From the data sample about 33 $\rm pb^{-1}$ taken around 3.773 GeV, 3 purely leptonic decay events of $D^+ \to μ^+ν$ are observed. The branching fraction and the decay constant are measured to be $BF(D^+ \to μ^+ν)=(0.120^{+0.092+0.010}_{-0.063-0.009}) %$ and $f_D=(365^{+121+32}_{-113-28})$ MeV. The semileptonic decay branching fractions for $D^0 \to K^-e^+ν$, $D^0 \to π^-e^+ν$ and $D^+ \to \bar K…

Implications of light-quark admixtures on charmonium decays into meson pairs

We argue that charmonium decays into meson pairs fall into two distinct classes: one that is under control of perturbative QCD and another one that is governed by a soft mechanism. We concentrate on a systematic analysis of J/Psi (Psi') decays into a light pseudoscalar and a light vector meson and eta(c) decays into a pair of light vector mesons. These processes belong to the second class and are characterized by non-conserved hadronic helicity. It is assumed that, in these cases, the charmonium state decays dominantly through a light-quark Fock component by a soft mechanism which is character…

$b \to c$ 半轻子求和规则：扩展到角观测量

$b \to c$ semileptonic sum rule: Extension to angular observables

本文提出基于重夸克对称性的 $b \to c$ 半轻子求和规则，用于验证实验结果的一致性，并探讨了其在现实情况下的修正和现象学意义。

D to K and D to pi semileptonic form factors from Lattice QCD

We present a very high statistics study of D and D_s semileptonic decay form factors on the lattice. We work with MILC N_f=2+1 lattices and use the Highly Improved Staggered Quark action (HISQ) for both the charm and the strange and light valence quarks. We use both scalar and vector currents to determine the form factors f_0(q^2) and f_+(q^2) for a range of D and D_s semileptonic decays, including D to pi and D to K. By using a phased boundary condition we are able to tune accurately to q^2=0 and explore the whole q^2 range allowed by kinematics. We can thus compare the shape in q^2 to that f…

Update on $|V_{us}|$ and $|V_{us}/V_{ud}|$ from semileptonic kaon and pion decays

We discuss the recent progress in the study of semileptonic kaon and pion decays, including new experimental results, improved electroweak radiative corrections, form factor calculations and isospin-breaking effects. As a result, we obtain $|V_{us}|=0.22309(40)(39)(3)$ from kaon semileptonic decays and $|V_{us}/V_{ud}|=0.22908(66)(41)(40)(2)(1)$ from the ratio between the kaon and pion semileptonic decay rates. We report an apparent violation of the top-row Cabibbo-Kobayashi-Maskawa matrix unitarity at a $3.2\sim 5.6σ$ level, and a discrepancy at a $2.2σ$ level between the value of $|V_{us}/V_…

Kaon semileptonic decays with $N_f=2+1+1$ HISQ fermions and physical light-quark masses

We discuss the reduction of errors in the calculation of the form factor $f_+^{K π}(0)$ with HISQ fermions on the $N_f=2+1+1$ MILC configurations from increased statistics on some key ensembles, new data on ensembles with lattice spacings down to 0.042 fm and the study of finite-volume effects within staggered ChPT. We also study the implications for the unitarity of the CKM matrix in the first row and for current tensions with leptonic determinations of $\vert V_{us}\vert$.

Analysis of D+ to K- pi+ e+ nu_e and D+ to K- pi+ mu+ nu_mu Semileptonic Decays

Using a large sample (~11800 events) of D^+ into K^- pi^+ e^+ nu_e and D^+ into K^- pi^+ mu^+ nu_mu decays collected by the CLEO-c detector running at the psi(3770), we measure the helicity basis form factors free from the assumptions of spectroscopic pole dominance and provide new, accurate measurements of the absolute branching fractions for D^+ into K^- pi^+ e^+ nu_e and D^+ into K^- pi^+ mu^+ nu_mu decays. We find branching fractions which are consistent with previous world averages. Our measured helicity basis form factors are consistent with the spectroscopic pole dominance predictions f…

D0 Evidence for CP Violation and Implication for CPT Violation in B-Meson Mixing

An analysis from the D0 Collaboration measuring the charge asymmetry A^b_sl of like-sign dimuon events due to semileptonic b-hadron decays at the Fermilab Tevatron Collider is described. It differs by 3.2 standard deviations from the Standard Model prediction to provide first evidence of CPT-invariant anomalous CP violation in the mixing of neutral B mesons, and is compared to the CP-violating phase obtained from a D0 analysis of the time-dependent decay angles in B0_s -> J/psi phi. If CPT violation is allowed, the dimuon asymmetry also yields the first sensitivity to CPT violation in the B0_s…

Measurement of Single Muons at Forward Rapidity in p+p Collisions at sqrt(s) = 200 GeV and Implications for Charm Production

Muon production at forward rapidity (1.5 < |η| < 1.8) has been measured by the PHENIX experiment over the transverse momentum range 1 < p_T \le 3 GeV/c in sqrt(s) = 200 GeV p+p collisions at the Relativistic Heavy Ion Collider. After statistically subtracting contributions from light hadron decays an excess remains which is attributed to the semileptonic decays of hadrons carrying heavy flavor, i.e. charm quarks or, at high p_T, bottom quarks. The resulting muon spectrum from heavy flavor decays is compared to PYTHIA and a next-to-leading order perturbative QCD calculation. PYTHIA is used to d…

Implications of the measurement of the B^0_s-\bar B^0_s mass difference

We analyze the significant new model independent constraints on extensions of the standard model (SM) that follow from the recent measurements of the B^0_s-\bar B^0_s mass difference. The time-dependent CP asymmetry in B_s -> ψϕ, S_{ψϕ}, will be measured with good precision in the first year of LHC data taking, which will further constrain the parameter space of many extensions of the SM, in particular, next-to-minimal flavor violation. The CP asymmetry in semileptonic B_s decay, A_{SL}^s, is also important to constrain these frameworks, and could give further clues to our understanding the fl…

Interplay of dineutrino modes with semileptonic rare $\boldsymbol{B}$-decays

We present a systematic global analysis of dineutrino modes $b \to q \,ν\bar ν$, $q=d,s$, and charged dilepton $b \to q \,\ell^+ \ell^-$ transitions. We derive improved or even entirely new limits on dineutrino branching ratios including decays $B^0 \to (K^0 , X_s)\, ν\bar ν$, $B_s \to ϕ\,ν\bar ν$ and $B^0 \to (π^0, ρ^0)\, ν\bar ν$ from dineutrino modes which presently are best constrained: $B^+ \to (K^+,π^+, ρ^+) \,ν\bar ν$ and $B^0 \to K^{*0} \,ν\bar ν$. Using SMEFT we obtain new flavor constraints from the dineutrino modes, which are stronger than the corresponding ones from charged dilepto…

On Indirect CP Violation and Implications for D0-\overline{D0} and Bs -\overline{Bs} mixing

The two kinds of indirect CP violation in neutral meson systems are related, in the absence of new weak phases in decay. The result is a model-independent expression relating CP violation in mixing, CP violation in the interference of decays with and without mixing, and the meson mass and width differences. It relates the semileptonic and time-dependent CP asymmetries; and CP-conjugate pairs of time-dependent $D^0$ CP asymmetries. CP violation in the interference of decays with and without mixing is related to the mixing parameters of relevance to model building: the off-diagonal mixing matrix…

无粲半轻子重子型 $B_{u,d,s}$ 衰变

Charmless Semileptonic Baryonic $B_{u,d,s}$ Decays

本文用拓扑振幅方法系统研究无粲半轻子重子型 $B_{u,d,s}$ 衰变，建立振幅关系并利用阈值增强效应估计 SU(3) 破缺影响，预言可探测模式及圈图与树图衰变速率比，为标准模型检验提供新途径。

Tetraquark Interpretation of the Charged Bottomonium-like states Z_b^+-(10610) and Z_b^+-(10650) and Implications

We present a tetraquark interpretation of the charged bottomonium-like states Z+-_b(10610) and Z+-_b(10650), observed by the Belle collaboration in the pi+- Upsilon(nS) (n=1,2,3) and pi+- h_b(mP) (m=1,2) invariant mass spectra from the data taken near the peak of the Upsilon(5S). In this framework, the underlying processes involve the production and decays of a vector tetraquark Y_b(10890), e+e- --> Y_b(10890) --> [Z+-_b(10610)pi-+, Z+-_b(10650)pi-+] followed by the decays [Z+-_b (10610), Z+-_b (10650)] --> pi+- Upsilon(nS), pi+- h_b(mP). Combining the contributions from the meson loops and an…