We study the properties of charmed, nonstrange, $\rm D$ mesons produced in continuum $\rm {e^+}{e^-}$ annihilations. The $ \rm {e^+}{e^-}$ collisions were generated in the energy region of the $ \rm Υ(3S)$ and $ \rm Υ(4S)$ resonances by the Cornell Electron Storage Ring, and were analyzed by the CLEO detector. We make extensive study of the decay topology $\rm D^0, D^+ \rightarrow \overline{\rm K}^{_{_0}}X$, where the $\overline{\rm K}^{_{_0}}$ is observed in the final state $\rm K^{0}_{S} \rightarrow π^+π^-$. The decay $ \rm D^+ \rightarrow K^- π^+π^-$ is also considered. We analyze the hadronization process through which charmed quarks become charmed hadrons. We measure the probability that a charmed meson will be produced in a state of non zero angular momentum. A comparison of the $\rm D^0$ and $\rm D^+$ fragmentation distributions is made to different fragmentation models, and to other charmed hadrons. A measurement of the relative production of several $\rm D^+$ decay modes is made, and the total $\rm D^0$ and $\rm D^+$ cross sections are estimated. Techniques are presented for the analysis of satellite mass peaks and $\rm D^+ \Leftrightarrow D^{+}_{s}$ reflections. We search for nonspectator effects in the weak decays of charmed mesons, and for evidence of hadronic final state interactions in $\rm D^0$ decay.
The di-electron width of an Upsilon meson is the decay rate of the Upsilon into an electron-positron pair, expressed in units of energy. We measure the di-electron width of the Upsilon(1S) meson to be 1.354 +- 0.004 +- 0.020 keV (the first uncertainty is statistical and the second is systematic), the di-electron width of the Upsilon(2S) to be 0.619 +- 0.004 +- 0.010 keV and that of the Upsilon(3S) to be 0.446 +- 0.004 +- 0.007 keV. We determine these values with better than 2% precision by integrating the Upsilon production cross-section from electron-positron collisions over their collision e…
Studies od the production of orbitally excited charmed and charmed strange mesons in e+e- collisions, performed by the LEP collaborations are reviewed. Measurements of the production rates of orbitally excited charmed mesons in semileptonic b decays are presented. Searches for charmed meson radial excitations are also briefly discussed.
We report a measurement of the production ratio of charged and neutral B mesons from Upsilon(4S) decays based on the ratio of efficiency-corrected yields for the charmonium modes J/psi K^+ and J/psi K^{0}_{S} with 81.9 fb^-1 of data collected with the BABAR detector on the Upsilon(4S) resonance at 10.580 GeV. We find a value of 1.006 +/- 0.036 (stat) +/- 0.031 (sys) for the ratio R^{+/0}=Gamma(Upsilon(4S) -> B^+ B^-)/Gamma(Upsilon(4S)->B^0 B^0bar).
We have performed a search for the eta_b(1S) meson in the radiative decay of the Upsilon(2S) resonance using a sample of 91.6 million Upsilon(2S) events recorded with the BABAR detector at the PEP-II B factory at the SLAC National Accelerator Laboratory. We observe a peak in the photon energy spectrum at E_gamma = 609.3 {+4.6} {-4.5} (stat) +/- 1.9 (syst) MeV, corresponding to an eta_b(1S) mass of 9394.2 {+4.8} {-4.9} (stat) +/- 2.0 (syst) MeV/c^2. The branching fraction for the decay Upsilon(2S) --> gamma eta_b(1S) is determined to be [3.9 +/-1.1 (stat) {+1.1} {-0.9} (syst)] x 10^(-4). We fin…
CDF has obtained new results on quarkonium production in p\bar{p} collisions at \sqrt{s} = 1.8 TeV. We report on measurements of Upsilon meson production, Upsilon(1S) production from Chi_b feeddown, and the production polarization of Upsilon(1S), J/Psi and Psi(2S) mesons.
Cross sections for elastic photoproduction of J/Psi and Upsilon mesons are presented. For J/Psi mesons the dependence on the photon-proton centre-of-mass energy W_gammap is analysed in an extended range with respect to previous measurements of 26<=W_gammap<= 285 GeV. The measured energy dependence is parameterized as sigma_gammap proportional W_gammap^delta with delta=0.83+-0.07. The differential cross section dsigma/dt for J/Psi mesons is derived, its dependence on W_gammap and on t is analysed and the effective trajectory (in terms of Regge theory) is determined to be alpha(t)=(1.27+-0.05)+(…
We search for invisible decays of the Upsilon(1S) meson using a sample of 91.4 x 10^{6} Upsilon(3S) mesons collected at the BaBar/PEP-II B-factory. We select events containing the decay Upsilon(3S) -> pi+ pi- Upsilon(1S) and search for evidence of an undetectable Upsilon(1S) decay recoiling against the dipion system. We set an upper limit on the branching fraction BR(Upsilon(1S) -> invisible) < 3.0 x 10^{-4} at the 90% confidence level.
We present measurements of the total production rates and momentum distributions of the charmed baryon $Λ_c^+$ in $e^+e^- \to$ hadrons at a center-of-mass energy of 10.54 GeV and in $Υ(4S)$ decays. In hadronic events at 10.54 GeV, charmed hadrons are almost exclusively leading particles in $e^+e^- \to c\bar{c}$ events, allowing direct studies of $c$-quark fragmentation. We measure a momentum distribution for $Λ_c^+$ baryons that differs significantly from those measured previously for charmed mesons. Comparing with a number of models, we find none that can describe the distribution completely.…
We report the preliminary measurement by the FOCUS Collaboration (E831 at Fermilab) of masses and widths of the L=1 charm mesons D_2^{*0} and D_2^{*+}.
Production of the Upsilon(1S) meson in association with a vector boson is a rare process in the standard model with a cross section predicted to be below the sensitivity of the Tevatron. Observation of this process could signify contributions not described by the standard model or reveal limitations with the current non-relativistic quantum-chromodynamic models used to calculate the cross section. We perform a search for this process using the full Run II data set collected by the CDF II detector corresponding to an integrated luminosity of 9.4/fb. The search considers the Upsilon(1S) to di-mu…
The lifetimes of charmed mesons have been measured using 11.1fb$^{-1} of data collected with the Belle detector at KEKB. Each candidate is fully reconstructed to identify the flavor of the charmed meson. The lifetimes are measured to be $τ(D^0)=(414.5\pm1.7)$ fs, $τ(D^+)=(1029\pm12)$ fs and $τ(D_s^+)=(488.4^{+7.8}_{-7.7})$ fs, where the error is statistical only. The mixing parameter $y_{CP}$ is also measured to be $y_{CP}=(1.16^{+1.67}_{-1.65}(stat.))%$ through the lifetime difference of $D^0$ mesons decaying into CP-mixed states and CP eigenstates.
Using 420 pb^-1 of data collected on the Upsilon(5S) resonance with the CLEO III detector, we reconstruct B mesons in 25 exclusive decay channels to measure or set upper limits on the decay rate of Upsilon(5S) into B meson final states. We measure the inclusive B cross-section to be sigma(Y(5S)-->BB(X))=(0.176+-0.030+-0.016) nb and make the first measurements of the production rates of sigma(Y(5S)-->B*B*)=(0.131+-0.025+-0.014) nb and sigma(Y(5S)-->BB*)=(0.043+-0.016+-0.006) nb, respectively. We set 90% confidence level limits of sigma(Y(5S)-->B B-bar)<0.038 nb, sigma(Y(5S)-->B(*)B(*)(pi))<0.05…
We present the first evidence for B semileptonic decays into the charmed baryon Lambda_c+ based on 420 fb-1 of data collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II e+e- storage rings. Events are tagged by fully reconstructing one of the B mesons in a hadronic decay mode. We measure the relative branching fraction BF(Bbar -> Lambda_c+ X l- nubar_l)/BF(Bbar -> Lambda_c+/Lambda_c- X) = (3.2 +/- 0.9_stat +/- 0.9_syst)%. The significance of the signal including the systematic uncertainty is 4.9 standard deviations.
Using data collected by the CLEO III detector at CESR, we started a series of investigations on the Upsilon(5S) resonance decay properties. The data sample used for this analysis consists of 0.42 fb-1 of data taken on the Upsilon(5S) resonance, 6.34 fb-1 of data collected on the Upsilon(4S) and 2.32 fb-1 of data taken in the continuum below the Upsilon(4S). B_s mesons are expected to decay predominantly into D_s meson, while the lighter B mesons decay into D_s only about 10% of the time. We exploit this difference to make a preliminary model dependent estimate of the ratio of B_s(*) anti-B_s(*…
We report the preliminary measurement by the FOCUS Collaboration (E831 at Fermilab) of masses and widths of the L=1 charm mesons $D_2^{*0}$ and $D_2^{*+}$. The fit of the invariant mass distribution requires an additional term to account for a broad structure over background.
We use data collected by the CLEO III detector at CESR on the Upsilon(5S) resonance to measure the inclusive yield of Ds mesons. Comparing with data taken on the Upsilon(4S), which decays into lighter B mesons, we make a model dependent estimate of the ratio of Bs(*)anti-Bs(*) to the total b anti-b quark pair production at the Upsilon(5S) energy of (16.0+/-2.6+/-5.8)%.
Pair production of Upsilon(1S) mesons is observed at the LHC in proton-proton collisions at sqrt(s) = 8 TeV by the CMS experiment in a data sample corresponding to an integrated luminosity of 20.7 inverse femtobarns. Both Upsilon(1S) candidates are fully reconstructed via their decays to mu+ mu-. The fiducial acceptance region is defined by an absolute Upsilon(1S) rapidity smaller than 2.0. The fiducial cross section for the production of Upsilon(1S) pairs, assuming that both mesons decay isotropically, is measured to be 68.8 +/- 12.7 (stat) +/- 7.4 (syst) +/- 2.8 (B) pb, where the third uncer…
We present the first measurement of the gluon polarisation in the nucleon based on the photon-gluon fusion process tagged by charmed meson production and decay to charged K and pi. The data were collected in polarised muon scattering off a polarised deuteron target by the COMPASS collaboration at CERN during 2002-2004. The result of this LO analysis is <Delta g/g>_x = -0.47 +- 0.44 (stat) +- 0.15 (syst) at <x> ~= 0.11 and a scale mu^2 ~ 13 (GeV/c)^2.
The lifetimes of charmed mesons have been measured using 2.75fb$^{-1}$ of data collected with the Belle detector at KEKB. Each candidate is fully reconstructed to identify the flavor of the charmed meson. The lifetimes are measured to be $τ(D^0)=(414.8\pm3.8\pm3.4)$ fs, $τ(D^+)=(1040^{+23}_{-22}\pm18)$ fs and $τ(D_s^+)=(479^{+17}_{-16}{}^{+6}_{-8})$ fs, where the first error is statistical and the second error is systematic. The mixing parameter $y_{CP}$ is also measured through the lifetime difference of $D^0$ mesons decaying into CP-mixed states and CP eigenstates. We find $y_{CP}=(1.0^{+3.8…
We report recent results of the Dalitz plot analyses of D and D_S decays performed by the BaBar collaboration, and point out some of the important applications of these results.
In the two years since HQL02, the long sought $j_{\ell}=1/2$ states have been observed. In the charmed non-strange sector, these states have the expected properties but, in the charmed strange sector, the states have masses below threshold for the otherwise dominant decay modes, allowing their observation in suppressed modes. Improved measurements of the masses and widths of the well established P-wave charm states have also been published.
The production of wrong sign charmed mesons b -> \bar D_{(s)} X, D_{(s)}=(D0,D+,D_s), is studied using the data collected by the DELPHI experiment in the years 1994 and 1995. Charmed mesons in Z -> b bbar events are exclusively reconstructed by searching for the decays D0 -> K- pi+, D+ -> K- pi+ pi+ and D_s^+ -> phi pi+ -> K+ K- pi+. The wrong sign contribution is extracted by using two discriminant variables: the charge of the b-quark at decay time, estimated from the charges of identified particles, and the momentum of the charmed meson in the rest frame of the b-hadron. The inclusive branch…
Using data collected with the BESII detector at $e^{+}e^{-}$ storage ring Beijing Electron Positron Collider, the measurements of relative branching fractions for seven Cabibbo suppressed hadronic weak decays $D^0 \to K^- K^+$, $π^+ π^-$, $K^- K^+ π^+ π^-$ and $π^+ π^+ π^- π^-$, $D^+ \to \bar{K^0} K^+$, $K^- K^+ π^+$ and $π^- π^+ π^+$ are presented.
We study the decay of Ds meson into final states involving a Ks and report the discovery of Cabibbo suppressed decay modes Ds -> Kspi-pi+pi+ (179 +/- 36 events) and Ds -> Kspi+ (113 +/-26 events). The branching ratios for the new modes are Gamma(Ds -> Kspi-pi+pi+)/Gamma(Ds -> KsK-pi+pi+) = 0.18 +/- 0.04 +/- 0.05 and Gamma(Ds -> Kspi+)/Gamma(Ds -> KsK+) = 0.104 +/- 0.024 +/- 0.013.
The ratio of charged and neutral B meson production at the Upsilon(4S), f_{+-}/f_{00}, is measured through the decays B bar -> D* l- nu_l bar, reconstructed using a partial reconstruction method where the D* is detected only through a pion daughter from the decay D* -> D pi. Using data collected by the CLEO II detector, the charged and neutral B decays are measured in such a way that their ratio is independent of decay model, limited mainly by the uncertainty in the relative efficiency for detecting neutral and charged pions. This measurement yields the ratio of production fractions times the …
We study the decay of D+ and Ds+ mesons into charged five body final states, and report the discovery of the decay mode D+ -> K+K-Pi+Pi+Pi-, as well as measurements of the decay modes D+ -> K-Pi+Pi+Pi+Pi-, Ds+ -> K+K-Pi+Pi+Pi-, Ds+ -> PhiPi+Pi+Pi- and D+/Ds+ -> Pi+Pi+Pi+Pi-Pi-. An analysis of the resonant substructure is also included, with evidence suggesting that both decays proceed primarily through an a1 vector resonance.
Two new states in the charm strange sector, DsJ(2317) and DsJ(2460), have recently been discovered at electron positron collider experiments. The new states are first observed in the dominant Ds pi0 and Ds* pi0 modes respectively and are very narrow. They are consistent with 0+ and 1+ P-wave charm anti-strange mesons. The DsJ(2460) meson is also observed in Ds gamma and Ds pi+ pi- modes. A review of the discoveries and possible explanations is given.
Based on data collected by the CLEO III detector at CESR, we started a series of investigations to open the mysteries of the $Υ$(5S) resonance decay properties. $B_s$ mesons are expected to decay predominantly into $D_s$ meson, while the lighter $B$ mesons decay into $D_s$ only about 10% of the time. We exploit this difference to present the first evidence of a substantial production of $B_s$ mesons at the $Υ$(5S) resonance. We make here a preliminary model dependent estimate of the ratio of $B_s^{(*)}\bar{B}_s^{(*)}$ to the total $b\bar{b}$ quark pair production at the $Υ$(5S) energy to be $(…
We search for a low-mass scalar CP-odd Higgs boson, A0, produced in the radiative decay of the Upsilon resonance and decaying into a tau+tau- pair: Upsilon(1S)->gamma A0. The production of Upsilon(1S) mesons is tagged by Upsilon(2S)->pi+pi-Upsilon(1S) transitions, using a sample of (98.3+/-0.9) million Upsilon(2S) mesons collected by the BaBar detector. We find no evidence for a Higgs boson in the mass range 3.5 GeV<= m(A0)<=9.2 GeV, and combine these results with our previous search for the tau decays of the light Higgs in radiative Upsilon(3S) decays, setting limits on the coupling of A0 to …
A first measurement of the $\mathrm{b}$ quark fragmentation function at the LHC is presented. Charmed meson candidates produced via semi-leptonic $\mathrm{t\overline{t}}$ decays ($\mathrm{t} \to \mathrm{b}\mathrm{W} \to$ b-jet $\ell ν$) are used as a proxy for the parent $\mathrm{B}$ meson. Templates are generated at various values of the fragmentation shape parameter $r_{\mathrm{b}}$, and are fit to the data to measure the value of $r_{\mathrm{b}}$. The final fit result is $r_{\mathrm{b}}=0.855 \pm 0.037\;\mathrm{(stat)} \pm 0.031\;\mathrm{(syst)}$. This is the first measurement of the $\math…
In the present work, we investigate the production of $P-$wave charmed or charmed-strange mesons in the pion or kaon induced reactions on a proton target. The total cross sections as well as the differential cross sections depending on the scattering angle are evaluated in an effective Lagrangian approach. Our estimations indicate that magnitude of the cross sections strongly depends on the model parameter but such dependence can be almost completely canceled for the cross section ratios. These model independent ratios can be taken as a good criterion of the validity of heavy quark limit in th…
Considering abundant experimental information of charmed mesons and the present research status, in this work we systematically study higher radial and orbital excitations in the charmed meson family by analyzing the mass spectrum and calculating their two-body OZI-allowed decay behaviors. This phenomenological analysis not only reveals underlying propertes of the newly observed charmed states $D(2550)$, $D^*(2600)$, $D^*(2760)$, $D(2750)$, $D_J(2580)$, $D^*_J(2650)$, $D^*_J(2760)$, $D_J(2740)$, $D_J(3000)$ and $D^*_J(3000)$, but also provides valuable information of the charmed mesons still m…
Stimulated by the newly reported doubly-charmed tetraquark state $T_{cc}^+$ by LHCb, we carry out a systematic investigation of the $S$-wave interactions between the charmed meson ($D,\,D^{*}$) in $H$-doublet and the charmed meson ($D_{1},\,D_{2}^{*}$) in $T$-doublet by adopting the one-boson-exchange model. Both the $S$-$D$ wave mixing effect and the coupled channel effect are taken into account. By performing a quantitative calculation, we suggest that the $S$-wave $D^{*} D_{1}$ states with $I(J^{P})=0(0^{-},\,1^{-})$ and the $S$-wave $D^{*}D_{2}^{*}$ state with $I(J^{P})=0(1^{-})$ should be…
Inspired by the present experimental status of charmed-strange mesons, we perform a systematic study of the charmed-strange meson family, in which we calculate the mass spectra of the charmed-strange meson family by taking a screening effect into account in the Godfrey-Isgur model and investigate the corresponding strong decays via the quark pair creation model. These phenomenological analyses of charmed-strange mesons not only shed light on the features of the observed charmed-strange states, but also provide important information on future experimental search for the missing higher radial an…
We review the status of recently observed positive parity charmed resonances, both in the non-strange and in the strange sector. We describe the experimental findings, the main theoretical analyses and the open problems deserving further investigations.
In this article, we tentatively identify the charmed mesons $D_J(2580)$, $D_J^*(2650)$, $D_J(2740)$, $D^*_J(2760)$, $D_J(3000)$, $D_J^*(3000)$ observed by the LHCb collaboration according to their spin, parity and masses, then study their strong decays to the ground state charmed mesons plus light pseudoscalar mesons with the heavy meson effective theory in the leading order approximation, and obtain explicit expressions of the decay widths. The ratios among the decay widths can be used to confirm or reject the assignments of the newly observed charmed mesons. The strong coupling constants in …
In the present paper, we continue our study the structure of hadronic spectra, started in Refs. \cite{1,2,3,4,5}, from the view point of existence the extra dimensions in the spirit of Kaluza-Klein approach. We show that all charmed and charmed-strange mesons, including the recently observed new states \cite{7,8}, are excellently incorporated in the systematics provided by Kaluza-Klein approach.
Two broad charmed mesons, the D_0^* and D_1', have recently been observed. We examine the quark model predictions for the D_0^* and D_1' properties and discuss experimental measurements that can shed light on them. We find that these states are well described as the broad, j=1/2 non-strange charmed P-wave mesons. Understanding the D_0^* and D_1' states can provide important insights into the D_{sJ}^*(2317), D_{sJ}(2460) states whose unexpected properties have led to renewed interest in hadron spectroscopy.
In the present work, we adopt a relativistic constituent quark model to depict the charmed strange meson spectroscopy, in which $D_{s0}(2317)$ and $D_{s1}(2460)$ are considered as the $1^3P_0$ and $1P_1^\prime$ charmed strange mesons, respectively. By using the wave function obtained from the relativistic quark model, we further investigate the electric transitions between charmed strange mesons. We find the long wave length approximation is reasonable for the charmed strange meson radiative decay by comparing the results with different approximations. The estimated partial widths are all safe…
Data on e+e- -> piplus-piminus-Upsilon(1S,2S,3S) show a large increase in branching fractions near Upsilon(10860). A suggestion of Ali et al. is to interpret this as evidence for a tetraquark, Yb(10890) = b-bbar. However, it may also be interpreted in terms of Upsilon(10860) -> B-B*, B*B* and BsB*s above the open-b threshold, followed by de-excitation processes such as $BB* -> Upsilon (1S,2S,3S). In the charm sector, a hypothesis open to experimental test is that X,Y and Z peaks in the mass range 3872 to 3945 MeV may all be due to regular 3P1 and 3P2 c-cbar states (and perhaps 3P0) mixed with …
Nonleptonic decays of charmed mesons into two pseudoscalar mesons or one pseudoscalar meson and one vector meson are studied on the basis of a generalized factorization method considering the resonance effects in the pole model for the annihilation contributions. Large strong phases between different topological diagrams are considered in this work, simply taking the phase in the coefficients $a_i$. We find that the annihilation-type contributions calculated in the pole model are large in both of the $PP$ and $PV$ modes, which make our numerical results agree with the experimental data better …
We present here recent open heavy-flavour results from the ALICE experiment, including measurements of D-meson, $\mathrm{Λ_{c}^{+}}$ baryon and $\mathrm{Ξ_c^0}$ baryon production in pp collisions at $\sqrt{s} = 7~\mathrm{TeV}$ and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02~\mathrm{TeV}$.
Using the CLEO-II detector, we have obtained evidence for a new meson decaying to $D^0 K^+$. Its mass is $2573.2^{+1.7}_{-1.6}\pm 0.8\pm 0.5$ {}~MeV/$c^2$ and its width is $16^{+5}_{-4}\pm 3$~MeV/$c^2$. Although we do not establish its spin and parity, the new meson is consistent with predictions for an $L=1$, $S=1$, $J_P=2^+$ charmed strange state.
The BaBar Collaboration has recently reported products of branching fractions that include $B$ meson semileptonic decays into final states with charged and neutral $D_{1}(2420)$ and $D_{2}^{\ast}(2460)$, two narrow orbitally excited charmed mesons. We evaluate these branching fractions, together with those concerning $D_{0}^{\ast}(2400)$ and $D_{1}'(2430)$ mesons, within the framework of a constituent quark model. The calculation is performed in two steps, one of which involves a semileptonic decay and the other is mediated by a strong process. Our results are in agreement with the experimenta…
Newly observed two charmed-strange resonances, $D_{s1}^*(2860)$ and $D_{s3}^*(2860)$, are investigated by calculating their Okubo-Zweig-Iizuka allowed strong decays, which shows that they are suitable candidates for the $1^3D_1$ and $1^3D_3$ states in the charmed-strange meson family. Our study also predicts other main decay modes of $D_{s1}^*(2860)$ and $D_{s3}^*(2860)$, which can be accessible at the future experiment. In addition, the decay behaviors of the spin partners of $D_{s1}^*(2860)$ and $D_{s3}^*(2860)$, i.e., $1D(2^-)$ and $1D^\prime(2^-)$, are predicted in this work, which are sti…
The hadronic decays of $χ_{c1}\to VV$ and $χ_{c2}\to VP$ are supposed to be suppressed by the helicity selection rule in the pQCD framework. With an effective Lagrangian method, we show that the intermediate charmed meson loops can provide a mechanism for the evasion of the helicity selection rule, and result in sizeable decay branching ratios in some of those channels. The theoretical predictions can be examined by the forthcoming BES-III data in the near future.
With the one-boson-exchange model we have studied the possible existence of the very loosely bound hidden-charm molecular baryons composed of anti-charmed meson and charmed baryon. Our numerical results indicate that there exist $Σ_c\bar{D}^*$ states with $I(J^P)=1/2(1/2^-), 1/2(3/2^-), 3/2(1/2^-), 3/2(3/2^-)$ and $Σ_c\bar{D}$ state with $3/2(1/2^-)$. But the $Λ_c \bar{D}$ and $Λ_c \bar{D}^*$ molecular states do not exist.
Within the framework of phenomenological Lagrangians we construct the effective action of QCD relevant for the study of semileptonic decays of charmed mesons. Hence we evaluate the form factors of D -> P(0^-) l^+ nu_l at leading order in the 1/N_C expansion and, by demanding their QCD-ruled asymptotic behaviour, we constrain the couplings of the Lagrangian. The features of the model-independent parameterization of form factors provided and their relevance for the analysis of experimental data are pointed out.
Higher excited charmed and charmed-strange mesons in an unquenched quark model
University of Chinese Academy of Sciences（中国科学院大学）；Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）；Hunan Normal University（湖南师范大学）
We study the process $B^- \to K^- χ_{c0}$ considering intermediate charmed meson rescattering effects. For this decay mode the naive factorization ansatz would predict a vanishing amplitude. We estimate contributions from the $D^{(*)}_{s} D^{(*)}\to K^- χ_{c0}$ rescattering amplitudes, and compare the result with recent experimental measurements. We find that rescattering effects are able to produce a large branching ratio consistent with measurements by Belle Collaboration. We also consider rescattering effects in $B^- \to K^- J/ψ$, arguing that they play a similar role in producing a large b…
High-accuracy $Υ$-meson photoproduction data from EIC and EicC experiments will allow the measurement of the near-threshold total cross section of the reaction $γp\toΥp$, from which the absolute value of the $Υp$ scattering length, $|α_{Υp}|$, can be extracted using a Vector-Meson Dominance model. For this evaluation, we used $Υ$-meson photoproduction quasi-data from the QCD approach (the production amplitude can be factorized in terms of gluonic generalized parton distributions and the quarkonium distribution amplitude). A comparative analysis of $|α_{Υp}|$ with the recently determined scatte…
The lightest charmed scalar meson is known as the $D_0^*(2300)$, which is one of the earliest new hadron resonances observed at modern $B$ factories. We show here that the parameters assigned to the lightest scalar $D$-meson are in conflict with the precise LHCb data of the decay $B^-\to D^+ π^- π^-$. On the contrary, these data can be well described by an unitarized chiral amplitude containing a much lighter charmed scalar meson, the $D_0^*(2100)$. We also extract the low-energy $S$-wave $Dπ$ phase of the decay $B^-\to D^+ π^- π^-$ from the data in a model-independent way, and show that its d…
In this work, we study the interaction between a nucleon and a $P$-wave charmed meson in the $T$ doublet by exchanging a pion. Our calculations indicate that a nucleon and a $P$-wave charmed meson with $J^P=0^+$ or $J^P=1^+$ in the $T$ doublet can form bound states. We propose the experimental search for these exotic molecular states near the $D_1(2420)N$ and $D_2^*(2460)N$ thresholds, where Belle, LHCb and the forthcoming Belle II have the discovery potential for them.
Exclusive electro-weak processes have peculiar features which make them complementary to usually discussed deeply virtual electroproduction processes such as deep virtual Compton scattering or meson production (and the corresponding crossed reactions). They allow in particular single charmed meson production, which we study in two different contexts : electroproduction at an electron ion collider and neutrino-production at a medium energy neutrino facility. We rely on the QCD collinear factorization framework where generalized parton distributions allow physicists to perform a nucleon tomograp…
We point out the physics opportunities of future high-luminosity B-factories at the Upsilon(5S) resonance and above. In this paper we discuss numerous interesting investigations, which can be performed in the e+e- centre-of-mass energy region from the Upsilon(5S) and up to 11.5 GeV, where an efficient data taking operation should be possible with the planned B-factories. These studies include abundant Bs production and decay properties; independent confirmation and if found, exhaustive exploration of Belle's claimed charged bottomonia; clarification of puzzles of interquarkonium dipion transit…
Including O(m_c) terms in the coefficient functions and/or O(m_D) twist 3 contributions in the heavy meson distribution amplitudes leads to a non-zero transverse amplitude for exclusive neutrino production of a D pseudoscalar charmed meson on an unpolarized target. We work in the framework of the collinear QCD approach where chiral-odd transversity generalized parton distributions (GPDs) factorize from perturbatively calculable coefficient functions.
The effects of intermediate charmed mesons on charmonium transitions with the emission of one pion or eta are studied systematically. Based on a non-relativistic effective field theory we show that charmed meson loops are enhanced compared to the corresponding tree-level contributions for transitions between two S-wave charmonia as well as for transitions between two P-wave charmonia. On the contrary, for the transitions between one S-wave and one P-wave charmonium state, the loops need to be analyzed case by case and often appear to be suppressed. The relation to and possible implications for…
