Charmed-strange Mesons Research Articles

Charm quark system at the physical point of2+1flavor lattice QCD

We investigate the charm quark system using the relativistic heavy quark action on 2+1 flavor PACS-CS configurations previously generated on $32^3 \times 64$ lattice. The dynamical up-down and strange quark masses are set to the physical values by using the technique of reweighting to shift the quark hopping parameters from the values employed in the configuration generation. At the physical point, the lattice spacing equals $a^{-1}=2.194(10)$ GeV and the spatial extent $L=2.88(1)$ fm. The charm quark mass is determined by the spin-averaged mass of the 1S charmonium state, from which we obtain $m_{\rm charm}^{\msbar}(\mu = m_{\rm charm}^{\msbar}) = 1.260(1)(6)(35)$ GeV, where the errors are due to our statistics, scale determination and renormalization factor. An additional systematic error from the heavy quark is of order $\alpha_s^2 f(m_Q a)(a \Lambda_{QCD})$, which is estimated to be a percent level if the factor $f(m_Q a)$ analytic in $m_Q a$ is of order unity. Our results for the charmed and charmed-strange meson decay constants are $f_D=226(6)(1)(5)$ MeV, $f_{D_s}=257(2)(1)(5)$ MeV, again up to the heavy quark errors of order $\alpha_s^2 f(m_Q a)(a \Lambda_{QCD})$. Combined with the CLEO values for the leptonic decay widths, these values yield $|V_{cd}| = 0.205(6)(1)(5)(9)$, $|V_{cs}| = 1.00(1)(1)(3)(3)$, where the last error is on account of the experimental uncertainty of the decay widths.

DandDsmeson spectroscopy

Results are presented for the low-lying spectrum of $D$ and ${D}_{s}$ mesons calculated in lattice QCD using $2+1$ flavor Clover-Wilson configurations made available by the PACS-CS collaboration. For the heavy quark, the Fermilab method is employed. The main focus is $S$- and $P$-wave states of charmed and charmed-strange mesons, where previous lattice QCD results have been mostly from quenched calculations. In addition to the ground states, some excited states are extracted. To check the method, calculations of the charmonium spectrum are also carried out. For charmonium, the low-lying spectrum agrees favorably with experiment. For heavy-strange and heavy-light systems substantial differences in comparison to experiment values remain for some states.

Possible heavy molecular states composed of a pair of excited charm-strange mesons

The P-wave charm-strange mesons Ds0(2317) and Ds1(2460) lie below the DK and D*K threshold respectively. They are extremely narrow because their strong decays violate the isospin symmetry. We study the possible heavy molecular states composed of a pair of excited charm strange mesons. As a byproduct, we also present the numerical results for the bottonium-like analogue.

Masses of tetraquarks with open charm and bottom

The masses of the heavy tetraquarks with open charm and bottom are calculated within the diquark–antidiquark picture in the framework of the relativistic quark model. The dynamics of the light quarks and diquarks is treated completely relativistically. The diquark structure is taken into account by calculating the diquark–gluon form factor. New experimental data on charmed and charmed-strange mesons are discussed. Our results indicate that the anomalous scalar Ds0⁎(2317) and axial vector Ds1(2460) mesons could not be considered as diquark–antidiquark bound states. On the other hand, Ds(2632) and DsJ⁎(2860) could be interpreted as scalar and tensor tetraquarks, respectively. The predictions for masses of the corresponding bottom counterparts of the charmed tetraquarks are given.

Search for rare and forbidden decays of charm and charmed-strange mesons to final statesh±e∓e+

We have searched for flavor-changing neutral current decays and lepton-number-violating decays of D^+ and D^+_s mesons to final states of the form h^+- e^-+ e^+, where h is either \pi or K. We use the complete samples of CLEO-c open-charm data, corresponding to integrated luminosities of 818 pb^-1 at the center-of-mass energy E_CM = 3.774 GeV containing 2.4 x 10^6 D^+D^- pairs and 602 pb^-1 at E_CM = 4.170 GeV containing 0.6 x 10^6 D^*+-_s D^-+_s pairs. No signal is observed in any channel, and we obtain 90% confidence level upper limits on branching fractions B(D^+ --> \pi^+ e^+ e^-) < 5.9 x 10^-6, B(D^+ --> \pi^- e^+ e^+) < 1.1 x 10^-6, B(D^+ --> K^+ e^+ e^-) < 3.0 x 10^-6, B(D^+ --> K^- e^+ e^+) < 3.5 x 10^-6, B(D^+_s --> \pi^+ e^+ e^-) < 2.2 x 10^-5, B(D^+_s --> \pi^- e^+ e^+) < 1.8 x 10^-5, B(D^+_s --> K^+ e^+ e^-) < 5.2 x 10^-5, and B(D^+_s --> K^- e^+ e^+) < 1.7 x 10^-5.

The molecular systems composed of the charmed mesons in the $H\bar{S}+h.c.$ doublet

We study the possible heavy molecular states composed of a pair of charm mesons in the H and S doublets. Since the P-wave charm-strange mesons D s0(2317) and D s1(2460) are extremely narrow, the future experimental observation of the possible heavy molecular states composed of \(D_{s}/D_{s}^{\ast}\) and D s0(2317)/D s1(2460) may be feasible if they really exist. Especially the possible J PC=1−− states may be searched for via the initial state radiation technique.

D0D̄0 mixing and other recent charm results from BABAR

Studies in which BABAR data have shown evidence for mixing in the neutral charm meson system are presented. A new measurement of the lifetime difference parameter yCP = (1.16±0.22±0.18)% is described. Results are also presented from a systematic study of DK and D*K invariant mass distributions from a 470 fb−1 sample of asymmetric e+e− interactions recorded by the BABAR detector at the PEP-II storage rings. A new charmed-strange meson has been observed with mass [3044±8stat(−5+30)syst] MeV/c2 and width [239±35stat(+46−42)syst]MeV/c2.

Measurement of absolute branching fractions of inclusive semileptonic decays of charm and charmed-strange mesons

We have measured the inclusive semileptonic branching fractions of $D^0$, $D^+$, and $D^+_s$ mesons. For these measurements, we have used the full CLEO-c open-charm data samples, 818 pb$^{-1}$ at $E_\text{CM} = 3.774$ GeV, giving $D^0 \bar{D}^0$ and $D^+ D^-$ events, and 602 pb$^{-1}$ at $E_\text{CM} = 4.170$ GeV, giving $D^{\ast \pm}_s D^\mp_s$ events. We obtain $\mathcal{B}(D^0 \to X e^+ \nu_e) = (6.46 \pm 0.09 \pm 0.11)$%, $\mathcal{B}(D^+ \to X e^+ \nu_e) = (16.13 \pm 0.10 \pm 0.29)$%, and $\mathcal{B}(D^+_s \to X e^+ \nu_e) = (6.52 \pm 0.39 \pm 0.15)$%, where the first uncertainties are statistical and the second are systematic. From these and lifetimes obtained elsewhere, we obtain the ratios of semileptonic decay widths $\Gamma (D^+ \to X e^+ \nu_e) / \Gamma (D^0 \to X e^+ \nu_e) = 0.985 \pm 0.015 \pm 0.024$ and $\Gamma (D^+_s \to X e^+ \nu_e) / \Gamma (D^0 \to X e^+ \nu_e) = 0.828 \pm 0.051 \pm 0.025$. The ratio of $D^+$ and $D^0$ is consistent with the isospin symmetry prediction of unity, and the ratio of $D^+_s$ and $D^0$ differs from unity, as expected.

Newly observedDsJ(3040)and the radial excitations of P-wave charmed-strange mesons

Inspired by the newly observed ${D}_{sJ}(3040{)}^{+}$ state, in this work we systemically study the two-body strong decays of P-wave charmed-strange mesons with the first radial excitation. Under the assignment of ${1}^{+}({j}^{P}={\frac{1}{2}}^{+})$, i.e. the first radial excitation of ${D}_{s1}(2460{)}^{+}$, we find that the width of ${D}_{sJ}(3040{)}^{+}$ is close to the lower limit of the BABAR measurement. This indicates that it is reasonable to interpret ${D}_{sJ}(3040{)}^{+}$ as the first radial excitation of ${D}_{s1}(2460{)}^{+}$. Our calculation further predicts that ${0}^{\ensuremath{-}}+{1}^{\ensuremath{-}}$ channels, e.g., ${D}^{+}{K}^{*0}$, ${D}^{0}{K}^{*+}$, and ${D}_{s}^{+}\ensuremath{\phi}$, are important for the search for ${D}_{sJ}(3040{)}^{+}$. To help future experiments find the remaining three P-wave charmed-strange mesons with the first radial excitation, we present the predictions for the strong decays of these three P-wave charmed-strange mesons.

Production of excited charm and charm-strange mesons at HERA

The production of excited charm, D_1(2420)^0 and D_2^*(2460)^0, and charm-strange, D_{s1}(2536)^+-, mesons in ep collisions was measured with the ZEUS detector at HERA using an integrated luminosity of 126 pb^-1. Masses, widths and helicity parameters were determined. The measured yields were converted to the rates of c quarks hadronising as a given excited charm meson and to the ratios of the dominant D_2^*(2460)^0 and D_{s1}(2536)^+- branching fractions. A search for the radially excited charm meson, D^{*'}(2640)^+-, was also performed. The results are compared with those measured previously and with theoretical expectations.

Leptoquarks in flavor changing neutral current charm decays

Recently it was noticed that among many scenarios of new physics leptoquarks might compensate for the disagreement between the lattice and experimental results for the charmed strange meson decay constant. The leptoquarks might modify also the flavor changing neutral current charm decays. In this study we investigate the impact of the scalar leptoquark with electric charge $\ensuremath{-}1/3$ on the dilepton invariant mass distribution in the ${D}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ decay and on the branching ratios of the ${D}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ using the existing experimental results.

Resonance Search and Particle Production at HERA

Searches for exotic strange baryon resonances decaying into K s 0 p , K s 0 p ¯ , and Ξ π were performed by the H1 collaboration in deep inelastic scattering (DIS) at HERA. Upper limits are given for the production rates. Deuterons and anti-deuterons were observed by the ZEUS collaboration and their production rates in DIS were compared to those of p ( p ¯ ) . Strange neutral hadrons were produced and cross-sections, baryon to meson ratios and relative yields of strange to light mesons were measured by ZEUS. Excited charm non-strange and strange mesons were produced and the fraction of charm quark fragmenting to these mesons was measured by ZEUS.

Charm production at HERA

Some recent results on charm physics obtained by the ZEUS experiment at HERA are reviewed. D-meson cross-section measurements are shown in the deep inelastic scattering (DIS) regime, in photoproduction (γp) and in the intermediate region. Measurements of charm fragmentation ratios and fractions, and analysis of charmed and charmed-strange mesons are also presented.

First nonperturbative test of a relativistic heavy quark action in quenched lattice QCD

We perform a numerical test of a relativistic heavy quark(RHQ) action, recently proposed by Tsukuba group, in quenched lattice QCD at $a\simeq 0.1$ fm. With the use of the improvement parameters previously determined at one-loop level for the RHQ action, we investigate a restoration of rotational symmetry for heavy-heavy and heavy-light meson systems around the charm quark mass. We focused on two quantities, the meson dispersion relation and the pseudo-scalar meson decay constants. It is shown that the RHQ action significantly reduces the discretization errors due to the charm quark mass. We also calculate the S-state hyperfine splittings for the charmonium and charmed-strange mesons and the $D_s$ meson decay constant. The remaining discretization errors in the physical quantities are discussed.

Dwave heavy mesons

We first extract the binding energy {lambda} and decay constants of the D wave heavy meson doublets (1{sup -},2{sup -}) and (2{sup -},3{sup -}) with QCD sum rule in the leading order of heavy quark effective theory. Then we study their pionic ({pi},K,{eta}) couplings using the light-cone sum rule, from which the parameter {lambda} can also be extracted. We then calculate the pionic decay widths of the strange/nonstrange D wave heavy D/B mesons and discuss the possible candidates for the D wave charm-strange mesons. Further experimental information, such as the ratio between D{sub s}{eta} and DK modes, will be very useful to distinguish various assignments for D{sub sJ}(2860 2715)

Charm mesons with DWF quarks on a quenched 3 GeV lattice

We present some preliminary results on charmed meson spectroscopy from a RIKEN-BNL-Columbia lattice numerical claculations. We use domain-wall fermions (DWF) for all quark flavors including charm. To make this meaningful we use quenched gauge ensemble with lattice cutoff a −1 of about 3 GeV obtained with the DBW2 rectangular improved action. With the strange quark mass estimate of m strange a = 0.030 from the associated kaon sector calculations, we obtain a charm mass estimate of m charm a = 0.360 ( 7 ) by fitting the D s meson mass. With these and additional extrapolations for light quark mass to the chiral limit, we discuss charmed D and D* and charm-strange ( D s and D s J ) mesons with spin-parity J P = 0 ± and 1 ± . We also discuss our preliminary results for the pseudoscalar meson (D and D s ) decay constants.

P-wave charmed-strange mesons

We examine charmed-strange mesons within the framework of the constituent quark model, focusing on the states with $L=1$. We are particularly interested in the mixing of two spin states that are involved in ${D}_{s1}(2536)$ and the recently discovered ${D}_{\mathit{sJ}}(2460)$. We assume that these two mesons form a pair of states with $J=1$. These spin states are mixed by a type of spin-orbit interaction that violates the total-spin conservation. Without assuming explicit forms for the interactions as functions of the interquark distance, we relate the matrix elements of all relevant spin-dependent interactions to the mixing angle and the observed masses of the $L=1$ quartet. We find that the spin-spin interaction, among various types of spin-dependent interactions, plays a particularly interesting role in determining the spin structure of ${D}_{s1}(2536)$ and ${D}_{\mathit{sJ}}(2460)$.

Towards an understanding of the new charm and charm-strange mesons

The observation of the DsJ*(2317), DsJ(2460), and SELEX DsJ*(2632) states with properties differing considerably from what was expected has led to a renewed interest in hadron spectroscopy. In addition to these states, non-strange partners of the DsJ states have also been observed. Understanding the D0* and D1′ states can provide important insights into the DsJ states. In this contribution I examine quark model predictions for the D0* and D1′ states and discuss experimental measurements that can shed light on them. I find that these states are well described as the broad, j = 1/2 non-strange charmed P-wave mesons. In the latter part of this writeup I discuss the cs̄ possibilities for the SELEX DsJ*(2632) and measurements that can shed light on it.

Production of P-wave charm and charm-strange mesons in hadronic Z $^0$ decays

Results are presented on the production of excited charm and excited charm-strange mesons in hadronic Z(0) decays. The results are obtained from approximately 4.3 million hadronic Z(0) decays, collected on or near the Z(0) resonance using the OPAL detector at LEP. The D-1(0)(2420) and D*(0)(2)(2460) mesons are reconstructed in the D*(+)pi(-) final state and their separate production rates in charm fragmentation and in weak decays of b-hadrons are determined. Assuming that the decay widths of these mesons are saturated by the allowed D*pi and D pi final states, the charm hadronization fractions and the inclusive branching ratios of b-hadrons to these neutral P-wave charm mesons are determined to bef(c --> D-1(0)) = 0.021 +/- 0.007(stat) +/- 0.003(syst), f(c --> D*(0)(2)) = 0.052 +/- 0.022(stat)+/- 0.013(syst), f(b --> D-1(0)) = 0.050 +/- 0.014(stat) +/- 0.006(syst), f(b --> D*(0)(2)) = 0.047 +/- 0.024(stat) +/- 0.013(syst).We also present the first observation at LEP of the D-s1(+)(2536) meson which is reconstructed in both the D*K-+(s)0 and D*K-0(+) final states After correcting for the expected contribution from bb events, assuming that the D*K channels saturate the available final states, these results are used to derive the charm hadronization fraction f(c --> D-s1(+)):f(c --> D-s1(+)) = 0.016 +/- 0.004(stat) +/- 0.003(syst).

Measurement of the decay D* S2 +(2573)→D0K+

Abstract Using the ARGUS detector at the e+e− storage ring DORIS II at DESY we have measured the parameters of a charmed strange meson D* s2 +(2573) decaying into D0K +. The mass of this state was found to be (2574·5 ± 3·3 ± 1·6) MeV/c2. The measured value of its width is (10·4 ± 8·3 ± 3·0) MeV and the product of the production cross section and branching ratio for this channel was determined to be (10·6 ± 4·2+2·3 −1·2) pb.