D-meson Decay Research Articles

FCNC charmed-hadron decays with invisible singlet particles in light of recent data

The flavor-changing neutral current (FCNC) decays of charmed hadrons with missing energy (Ɇ) can serve as potentially promising hunting grounds for hints of new physics, as the standard-model backgrounds are very suppressed. A few of such processes have been searched for in recent experiments, specifically D0→ Ɇ by Belle and D0→ π0Ɇ and Λc+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\Lambda}_c^{+} $$\\end{document}→ pɆ by BESIII, resulting in upper bounds on their branching fractions. We consider them to illuminate the possible contributions of the quark transition c → uɆ with a couple of invisible spinless bosons carrying away the missing energy, assuming that they are not charge conjugates of each other and hence can have unequal masses. We find that these data are complementary in that they constrain different sets of the underlying operators and do not cover the same ranges of the bosons’ masses, but there are regions not yet accessible. From the allowed parameter space, we show that other D-meson decays, such as D → ρɆ, and the charmed-baryon ones Ξc → (Σ, Λ)Ɇ can have sizable branching fractions and therefore may offer further probes of the new-physics interactions. We point out the importance of D0 → γɆ which are not yet searched for but could access parts of the parameter space beyond the reach of the other modes. In addition, we look at a scenario where the invisibles are instead fermionic, namely sterile neutrinos, and a scalar leptoquark mediates c → uɆ. We discuss the implications of the aforesaid bounds for this model. The predictions we make for the various charmed-hadron decays in the different scenarios may be testable in the near future by BESIII and Belle II.

Testing Heavy Neutral Leptons in Cosmic Ray Beam Dump experiments

In this work, we discuss the possibility to test Heavy Neutral Leptons (HNLs) using “Cosmic Ray Beam Dump” experiments. In analogy with terrestrial beam dump experiments, where a beam first hits a target and is then absorbed by a shield, we consider high-energy incident cosmic rays impinging on the Earth’s atmosphere and then the Earth’s surface. We focus here on HNL production from atmospherically produced kaon, pion and D-meson decays, and discuss the possible explanation of the appearing Cherenkov showers observed by the SHALON Cherenkov telescope and the ultra-high energy events detected by the neutrino experiment ANITA. We show that these observations can not be explained with a long-lived HNL, as the relevant parameter space is excluded by existing constraints. Then we propose two new experimental setups that are inspired by these experiments, namely a Cherenkov telescope pointing at a sub-horizontal angle and shielded by the mountain cliff at Mount Thor, and a geostationary satellite that observes part of the Sahara desert. We show that the Cherenkov telescope at Mount Thor can probe currently untested HNL parameter space for masses below the kaon mass. We also show that the geostationary satellite experiment can significantly increase the HNL parameter space coverage in the whole mass range from 10 MeV up to 2 GeV and test neutrino mixing |Uα4|2 down to 10−11 for masses around 300 MeV.

Factorization of radiative leptonic D-meson decay with sub-leading power corrections * *Supported in part by the National Natural Science Foundation of China (1675082, 11735010), and the Natural Science Foundation of Tianjin (19JCJQJC61100)

In this work, we calculate the sub-leading power contributions to radiative leptonic decay. For the first time, we provide the analytic expressions of next-to-leading power contributions and the error estimation associated with the power expansion of . In our calculation, we adopt two different models of the D-meson distribution amplitudes and . Within the framework of QCD factorization as well as the dispersion relation, we evaluate the soft contribution up to the next-to-leading logarithmic accuracy and also consider the higher-twist contribution from the two-particle and three-particle distribution amplitudes. Finally, we find that all the sub-leading power contributions are significant at MeV, and the next-to-leading power contributions lead to 143% in and 120% in corrections to leading power vector form factors with GeV. As the corrections from the higher-twist and local sub-leading power contributions are enhanced with increasing inverse moment, it is difficult to extract an appropriate inverse moment of the D-meson distribution amplitude. The predicted branching fractions are for and for .

D Meson Leading-Twist Distribution Amplitude from $B\to Dl\bar {\nu }_{l}$ Semi-Leptonic Decay

The D-meson leading-twist distribution amplitude (DA) is an universal physical quantity for applying QCD light-cone sum rules or perturbative QCD method to exclusive processes involving D-meson. Although several models have been used in the literature, we do not have enough knowledge to determine it. Inversely, one expects that the D-meson DA can be constrained in principle by the processes containing D-meson. In this paper, we try to extract the information of D-meson DA’s behavior from the experimental data of B → D semi-leptonic decay. A revised light-cone harmonic oscillator model has been suggested. It can mimic most of the suggested D-meson DA behaviors, whose parameters can be fixed by the constraints from the processes involving D-meson. By combining the D-meson decay channel $D\to \mu \bar {\nu }$ , the semi-leptonic decay $B\to Dl\bar {\nu }_{l}$ and the constrain that the probability of finding the leading Fock-state $|\bar {c}q>$ in the D-meson Fock state expansion, we restrict the parameter BD in our DA model as BD ∈ [0.00, 0.23]. In order to improve the complexity of the evolution of the oscillator model, we give the fitting formulas for the evolution of the model parameters. Then we calculate the branching ratios ${\mathscr{B}}(\overline {B}^{0}\to D^{+}l\nu _{l})$ and ${\mathscr{B}}(B^{-}\to D^{0}l\bar {\nu }_{l})$ , which agree with the experimental data.

Non prompt D-meson measurements with ALICE at the LHC

The production of hadrons with open heavy flavour (charm and beauty) in high-energy nucleus-nucleus collisions is a powerful tool to study the properties of the deconfined phase of strongly interacting matter known as the Quark-Gluon Plasma (QGP). The production of charm and beauty quarks occurs in hard partonic scattering processes in the early stage of the collisions. ALICE is the LHC experiment devoted to the study of heavy-ion physics. It is able to reconstruct charmed mesons in exclusive decays (e.g. D0 →K− π + ) and beauty hadrons in semi-inclusive decays (e.g. B→eX, B→J/ψ X) . At LHC energies a significant component of the inclusive D-meson yield originates from the decay of beauty-flavoured hadrons, whose knowledge is essential to determine the production of prompt D mesons coming from charm quarks. A precise determination of the non-prompt fraction combined with the determination of the inclusive D-meson yield would allow a measurement of beauty production. A data-driven method that exploits the different shapes of the distributions of the transverse-plane impact parameter to the primary vertex of prompt and feed-down D mesons in p-Pb collisions is used in ALICE. An alternative approach based on the D-meson decay length for Pb–Pb collisions is under study.

On the significance of B-decays to the radially excited D

We discuss the possibilities of testing the recent claims of a relatively large B→D′ transition form factor through the non-leptonic B¯0→D′+π− and B−→D′0π− decay modes. To estimate the width of the latter we need the decay constant of the radially excited D-meson that we computed in lattice QCD with Nf=2 dynamical flavors and after taking the continuum limit we found fD′=117(25) MeV. We also provide an update for the values of the D-meson decay constants obtained by using maximally twisted mass QCD.

D-meson decay constants and a check of factorization in non-leptonic B-decays

Abstract We compute the vector meson decay constants $ {f_{{D_{{(s)}}^{ * }}}} $ from the simulation of twisted mass QCD on the lattice with N f = 2 dynamical quarks. When combining these values with the pseudoscalar D (s)-meson decay constants, we were able (i) to show that the heavy quark spin symmetry breaking effects with the charm quark are large, $ {f_{{D_s^{ * }}}}/{f_{{{D_s}}}} = 1.26(3) $ , and (ii) to check the factorization approximation in a few specific B-meson non-leptonic decay modes. Besides our main results, $ {f_{{{D^{ * }}}}} = 278\pm 13\pm 10\,{\text{MeV}} $ , and $ {f_{{D_s^{ * }}}} = 311\pm 9\,{\text{MeV}} $ , other phenomenologically interesting results of this paper are: $ {f_{{D_s^{ * }}}}/{f_{{{D^{ * }}}}} = 1.16\pm 0.02\pm 0.06 $ , $ {f_{{D_s^{ * }}}}/{f_{{{D^{ * }}}}} = 1.46\pm 0.05\pm 0.06 $ , and $ {f_{{{D_s}}}}/{f_{{{D^{ * }}}}} = 0.89\pm 0.02\pm 0.03 $ . Finally, we correct the value for B(B 0 → D + π −) quoted by PDG, and find B(B 0 → D + π −) = (7.8 ± 1.4) × 10−7. Alternatively, by using the ratios discussed in this paper, we obtain B(B 0 → D + π −) = (8.3 ± 1.0 ± 0.8) × 10−7.

Determining the η−η′ mixing by the newly measured $\mathit{BR}(D(D_{s})\to\eta(\eta')+\bar{l}+\nu_{l}$

The mixing of $\eta-\eta'$ or $\eta-\eta'-G$ is of a great theoretical interest, because it concerns many aspects of the underlying dynamics and hadronic structure of pseudoscalar mesons and glueball. Determining the mixing parameters by fitting data is by no means trivial. In order to extract the mixing parameters from the available processes where hadrons are involved, theoretical evaluation of hadronic matrix elements is necessary. Therefore model-dependence is somehow unavoidable. In fact, it is impossible to extract the mixing angle from a unique experiment because the model parameters must be obtained by fitting other experiments. Recently $BR(D\to\eta+\bar l+\nu_l)$ and $BR(D_s\to\eta(\eta')+\bar l+\nu_l)$ have been measured, thus we are able to determine the $\eta-\eta'$ mixing solely from the semileptonic decays of D-mesons where contamination from the final state interactions is absent. Thus we hope that the model-dependence of the extraction can be somehow alleviated. Once $BR(D\to\eta'+\bar l+\nu_l)$ is measured, we can further determine all the mixing parameters for $\eta-\eta'-G$. As more data are accumulated, the determination will be more accurate. In this work, we obtain the transition matrix elements of $D_{(s)}\to \eta^{(\prime)}$ using the light-front quark model whose feasibility and reasonability for such processes have been tested.

The Kπ and ππ S-wave amplitude from D-meson decays

The issue of Kπ and ππ S-wave amplitude is addressed using decays of D-mesons. Model-independent measurements of the phases of the π + π + and K − π + S-wave amplitude from D + → π − π + π + and D + → K − π + π + decays are discussed. The result indicates a deviation from the phase of the K − π + S-wave amplitude obtained by scattering experiments. This could be interpreted as an indication of the presence of 3-body final-state interaction, or in other words, that the phases from production and scattering process cannot be directly compared.

Semileptonic D decay into scalar mesons

Semileptonic decays of D-mesons into scalar hadronic states are investigated. Two extreme cases are considered: a) the meson decays directly into an uncorrelated scalar state of two mesons and b) the decay proceeds via resonance formation. QCD sum rules including instanton contributions are used to calculate total and differential decay rates under the two assumptions.

Phenomenology of neutral D-meson decays and double-flavour oscillations

Decays of neutral D-mesons are considered phenomenologically without invoking any particular models. Special attention is given to cascade decays with intermediate neutral kaons where coherent double-flavour oscillations (CDFO) become possible. We show necessity and unique possibilities of experiments on CDFO. They allow to relate with each other widths and masses of D-meson eigenstates, to separate interference effects due to D 0-¯D 0 mixing and/or Cabibbo-favoured vs. doubly-suppressed transitions. Such experiments provide the only known ways to unambiguous model-independent measurements of all CP-violating parameters and of Cabibbo-doubly-suppressed amplitudes, where the New Physics may have more prominent manifestations. Similar experiments would be useful and interesting also for charged D-meson decays to neutral kaons.

Erratum: Weak decays ofDmesons to pseudoscalar-tensor final states [Phys. Rev. D49, 1645 (1994)

Erratum: Weak decays of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>D</mml:mi></mml:math>mesons to pseudoscalar-tensor final states [Phys. Rev. D<b>49</b>, 1645 (1994)

Factorization and vector symmetry in heavy-meson decays

We investigate to what extent the effective theory of the vector symmetry satisfies the factorization assumption in the hadronic Cabibbo-allowed two-body decays of D-mesons. Some conclusions from the factorization assumption and the vector symmetry in two-body hadronic B-decays are compared with experiment.

Hadron spectrum and matrix elements in QCD with dynamical Wilson fermions at 6/g2=5.3.

We present results of a lattice simulation of quantum chromodynamics with two degenerate flavors of dynamic Wilson fermions at $6/g^2=5.3$ at each of two dynamical fermion hopping parameters, $\kappa=0.1670$ and 0.1675, corresponding to pion masses in lattice units of about 0.45 and 0.31. The simulations include three other values of valence quark mass, in addition to the dynamical quarks. We present calculations of masses and of the decay constants of vector mesons and of pseudoscalars, including the D-meson decay constant. The effects of sea quarks on matrix elements and spectroscopy are small.

D decays into pseudoscalar and scalar mesons

In this paper, we study the pseudoscalar-scalar meson (PS) weak decays ofD-mesons in the non-relativistic quark model using factorization scheme. Branching ratios for the Cabibbo angle-favored decays are calculated.

An application of the [formula omitted] within the heavy-quark effective theory: the B-meson decays [formula omitted

We analyze B-meson decays of the type B a → D a D ̄ b by using the 1 N C - expansion within the Heavy-Quark Effective Theory. Expanding the corresponding low energy effective hamiltonian H eff up to next-to-leading order in 1 N C , we are in a position to cancel the renormalization point dependence by introducing the D-meson decay constant f D and Isgur-Wise form factors into the calculation. Evaluating chiral logarithmic corrections to the hadronic matrix elements of H eff by using Heavy-Meson Chiral Perturbation Theory, we estimate SU(3) V-breaking long-distance contributions which are of next-to-leading order in the 1 N C - expansion . Numerical results are presented for BR(B − → D 0D s −) and BR(B − → D 0D s −)/BR(B − → D 0D s −).

Decay of the D-mesons

The channels of the decays of D-mesons are deduced from the Lagrangians formed on theL⊗O94) invariance and the principle of minimal structure. The consideration of these Lagranginas leads to the confirmation that the D+ and D0 are antiparticles. The probabilities of different decay types are estimated.

Two-body nonleptonic decays ofD mesons

The amplitudes for two-body Cabibbo allowed nonleptonic decays ofD mesons are evaluated within the factorization approximation from the effective Hamiltonian including short distance QCD corrections to next-to-leading order. Annihilation andW-exchange contributions as well as final state interaction effects have been included and are in fact crucial to obtain agreement with the experimental data.

Nonstrange D-meson decay modes with η and η′. Sensitive tests for small amplitudes, final state interactions and CP violation

Interference terms between weak amplitudes producing the η and η′ nonstrange components belonging to different weak generations have opposite signs for the two states and may have nontrivial CP-violating phases. Such interference effects are suggested by the experimentally observed enhancements of D s→πη′, D s→ϱη′ and D→Kη′ decays over corresponding η decay modes and their absence in D +- decays, where the analogous interference term has the same sign for η and η′ and should produce no enhancement. General relations testing different weak decay modes are derived for charmed meson decays into isovector two-body final states emphasizing the role of linear interference effects as a much more sensitive test for small amplitudes than quadratic direct contributions. Particularly simple relations between D s decays follow from assuming dominance of the tree diagram c→su d and neglecting OZI-violating final state rescattering.

First calculation of [formula omitted] in lattice QCD

We present the results of a calculation of the matrix elements of the quark weak current which are relevant for semileptonic decays of D-mesons into light pseudoscalar and vector mesons. The computations are performed by averaging the results over 15 gauge field configurations, generated in the quenched approximation by the Metropolis algorithm, at β = 6.0, on a 20 X 10 2 X 40 lattice, with Wilson fermions. From the study of the matrix elements 〈 K −| J μ | D 0〉 and 〈 K ∗0|J μD +〉 we find the partial rate for the semi-leptonic decay of the D + into K ∗0 e +ν e is given by Γ( D + → K ∗0 e +ν e ) = (5.2±1.9) X 10 10 s −1 , in good agreement with the experimental result (4.1 ± 0.7 ± 0.5) X 10 10 s −1, and that the ratio of the partial rates Γ( D + → K ∗0 e +ν e ) Γ( D ) → K − e +ν c ) is given by 1.1±1.3, which is larger than the experimental value 0.45 ± 0.09 ± 0.07. We also compute the ratio of the longitudinal to transverse polarization rates in K ∗0 decays and find 1.7 ± 0.6, to be compared to the experimental value 2.4 −0.9 +1.7 ± 0.2. We finally discuss future improvements in the accuracy of our theoretical predictions.