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Results for “CHARMED MESONS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Charm meson and charm-meson molecule in an expanding hadron gas

We present our studies on the evolution of charm mesons after the kinetic freeze-out of the expanding hadron gas produced in a heavy-ion collision and the thermal correction to a loosely bound charm-meson molecule in a pion gas. The πD* → πD* reaction rates have t-channel singularities that give contributions inversely proportional to the thermal width of the D. The ratio of the D 0 and D + production rate can differ significantly from those predicted using the measured D* branching fractions. The thermal correction to a loosely bound charm-meson molecule in a pion gas comes primarily from the complex thermal energy shift of the charm-meson constituents.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Nonleptonic two-body decays of charmed mesons

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{sub 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 than those previous calculations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Thermal energy of a charm-meson molecule in a pion gas

The thermal corrections to the propagator of a loosely bound charm-meson molecule in a pion gas are calculated to next-to-leading order in the heavy-meson expansion using a zero-range effective field theory. Ultraviolet divergences in the charm-meson-pair self energy are canceled by corrections to the charm-meson-pair contact vertex. Terms that are singular at the charm-meson-pair threshold can be absorbed into thermal corrections to the rest energies and kinetic masses of the charm-meson constituents. The remaining terms reduce to a thermal correction to the binding momentum that is proportional to the pion number density and suppressed by the pion/charm-meson mass ratio. The correction gives a tiny decrease in the binding energy of the charm-meson molecule relative to the charm-meson-pair threshold in the pion gas and a change in its thermal width that is small compared to the thermal widths of the charm-meson constituents. These results are encouraging for the prospects of observing X(3872) and $T$$^{+}_{cc}$ (3875) in the expanding hadron gas produced by heavy-ion collisions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Quasibound states in the continuum: A dynamical coupled-channel calculation of axial-vector charmed mesons

Masses and widths of the axial-vector charmed mesons D{sub 1}(2420), D{sub 1}(2430), D{sub s1}(2536), and D{sub s1}(2460) are calculated nonperturbatively in the resonance-spectrum-expansion model, by coupling various open and closed meson-meson channels to the bare J{sup P}=1{sup +} cq (q=u, d) and cs states. The coupling to two-meson channels dynamically mixes and lifts the mass degeneracy of the spectroscopic {sup 3}P{sub 1} and {sup 1}P{sub 1} states, as an alternative to the usual spin-orbit splitting. Of the two resulting S-matrix poles in either case, one stays very close to the energy of the bare state, as a quasibound state in the continuum, whereas the other shifts considerably. This is in agreement with the experimental observation that the D{sub 1}(2420) and D{sub s1}(2536) have much smaller widths than one would naively expect. The whole pattern of masses and widths of the axial-vector charmed mesons can thus be quite well reproduced with only two free parameters, one of which being already strongly constrained by previous model calculations. Finally, predictions for pole positions of radially excited axial-vector charmed mesons are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Production cross sections of light and charmed mesons in 𝑒 + ⁢𝑒 − annihilation near 10.58 GeV

We report measurements of production cross sections for 𝜌 + , 𝜌 0 , 𝜔, 𝐾* + , 𝐾* 0 , 𝜙, 𝜂, 𝐾$^0_𝑆$, 𝑓 0 ⁡(980), 𝐷 + , 𝐷 0 , 𝐷$^+_𝑠$, 𝐷* + , 𝐷* 0 , and 𝐷*$^+_𝑠$ in 𝑒 + ⁢𝑒 − collisions at a center-of-mass energy near 10.58 GeV. The data were recorded by the Belle experiment, consisting of 571 fb −1 at 10.58 GeV and 74 fb −1 at 10.52 GeV. Production cross sections are extracted as a function of the fractional hadron momentum 𝑥 𝑝 . The measurements are compared to pythia Monte Carlo generator predictions with various fragmentation settings, including those that have increased fragmentation into vector mesons over pseudoscalar mesons. The cross sections measured for light hadrons are consistent with no additional increase of vector over pseudoscalar mesons. The charmed-meson cross sections are compared to earlier measurements—when available—including older Belle results, which they supersede. They are in agreement before application of an improved initial-state radiation correction procedure that causes slight changes in their 𝑥 𝑝 shapes.

fragmentation functions↗
DOE OSTI2014

Interactions of Charmed Mesons with Light Pseudoscalar Mesons from Lattice QCD and Implications on the Nature of the D* s0 (2317)

We study the scattering of light pseudoscalar mesons ( p , K ) off charmed mesons ( D , D s ) in full lattice QCD. The S -wave scattering lengths are calculated using Luscher’s finite volume technique. We use a relativistic formulation for the charm quark. For the light quark, we use domain- wall fermions in the valence sector and improved Kogut-Susskind sea quarks. We calculate the scattering lengths of isospin-3/2 Dπ , D s π , D s K , isospin-0 DK and isospin-1 DK channels on the lattice. For the chiral extrapolation, we use a chiral unitary approach to next-to-leading order, which at the same time allows us to give predictions for other channels. It turns out that our results support the interpretation of the D* s0 ( 2317 ) as a DK molecule. At the same time, we also update a prediction for the isospin breaking hadronic decay width G ( D* s0 ( 2317 )→ D s π ) to ( 133± 22 ) keV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Combined large-N{sub c} and heavy-quark operator analysis of two-body meson-baryon counterterms in the chiral Lagrangian with charmed mesons

The chiral SU(3) Lagrangian with pseudoscalar and vector D mesons and with the octet and decuplet baryons is considered. The leading two-body counter terms involving two baryon fields and two D meson fields are constructed in the open-charm sector. There are 26 terms. A combined expansion in the inverse of the charm quark mass and in the inverse of the number of colors provides sum rules that reduce the number of free parameters down to 5 only. Our result shows the feasibility of a systematic computation of the open-charm baryon spectrum based on coupled-channel dynamics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Measurement of CP asymmetries and branching fraction ratios of B – decays to two charm mesons

The CP asymmetries of seven B – decays to two charm mesons are measured using data corresponding to an integrated luminosity of 9 fb –1 of proton-proton collisions collected by the LHCb experiment. Decays involving a D *0 or ${D}_s^{\ast -}$ meson are analysed by reconstructing only the D 0 or ${D}_s^{-}$ decay products. This paper presents the first measurement of $\mathcal{A}$ CP (B – → ${D}_s^{\ast -}$ D 0 ) and $\mathcal{A}$ CP (B – → ${D}_s^{-}$D $\ast$0 ), and the most precise measurement of the other five CP asymmetries. There is no evidence of CP violation in any of the analysed decays. Additionally, two ratios between branching fractions of selected decays are measured.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Semileptonic B and B{sub s} decays into orbitally excited charmed mesons

The BABAR Collaboration has recently reported products of branching fractions that include B meson semileptonic decays into final states with charged and neutral D{sub 1}(2420) and D{sub 2}*(2460), two narrow orbitally excited charmed mesons. We evaluate these branching fractions, together with those concerning D{sub 0}*(2400) and D{sub 1}{sup '}(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 experimental data. We also extend the study to semileptonic decays of B{sub s} into orbitally excited charmed-strange mesons, providing predictions to the possible measurements to be carried out at LHC.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Multiplicity dependence of charm baryon and charm meson production in pPb collisions at $\sqrt{s_{NN}} = 8.16$ TeV

Measurements of the production yields of charm baryons (Λ$^+_c$ ) and charm mesons (D 0 ) in proton-lead collisions at a nucleon-nucleon center-of-mass energy of 8.16 TeV are presented. The data were collected in 2016 with the CMS experiment and correspond to an integrated luminosity of 186 nb -1 . The Λ$^+_c$ baryon is reconstructed from the decay channel Λ$^+_c$ → K$^0_S$p , while the D 0 meson is reconstructed via D 0 → K - π + . The Λ$^+_c$ baryon and D 0 meson yields are extracted in several charged-particle multiplicity classes. No strong multiplicity dependence of the Λ$^+_c$-to-D 0 yield ratio is observed, unlike the observed strange baryon to strange meson yield ratio of $Λ/\bar{Λ}$to K$^0_S$, which shows a strong multiplicity dependence. This observation indicates different mechanisms for the multiplicity evolution of hadronization processes for charm and strange quarks and provides new constraints to the understanding of heavy flavor production and collectivity in small collision systems.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Updated search for $ {B}_c^{+} $ decays to two charm mesons

A data set corresponding to an integrated luminosity of 9 fb -1 of proton-proton collisions collected by the LHCb experiment has been analysed to search for B c + → D s ∗ + — D ∗ 0 decays. The decays are fully or partially reconstructed, where one or two missing neutral pions or photons from the decay of an excited charm meson are allowed. Upper limits for the branching fractions, normalised to B + decays to final states with similar topologies, are obtained for sixteen $ {B}_c^{+} $ decay modes. For the decay $ {B}_c^{+}\to {D}_s^{+}{\overline{D}}^0 $, an excess with a significance of 3.4 standard deviations is found.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Novel method for the identification of the production flavor of neutral charmed mesons

We propose a new algorithm for the identification of the production flavor of neutral D mesons in the Belle II experiment. The algorithm exploits the correlation between the flavor of a reconstructed neutral D meson (signal D meson) and the electric charges of particles reconstructed in the rest of the e + e – →$c\bar{c}$ event. These include those originating from the decay of the other charm hadron produced in the event, as well as those possibly produced in association with the signal D meson. We develop the algorithm using simulation and calibrate it in data using decay modes that identify the flavor of the decaying neutral D meson. We use a data sample of e + e – collisions, corresponding to 362 fb –1 of integrated luminosity, collected by Belle II at center-of-mass energies near the Υ(4S) mass. The effective tagging efficiency in data is (47.91±0.07 (stat) ±0.51 (syst)) %, independent of the neutral-D-meson decay mode. This charm flavor tagger will approximately double the effective sample size of many CP-violation and charm-mixing measurements that so far have exclusively relied on neutral D mesons originating from D* ± decays. While developed for Belle II, the basic principles underlying the charm flavor tagger can be used in other experiments, including those at hadron colliders.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Observation of strangeness enhancement with charmed mesons in high-multiplicity p Pb collisions at s NN = 8.16 TeV

The production of prompt D s + and D + mesons is measured by the LHCb experiment in proton-lead ( p Pb ) collisions in both the forward ( 1.5 < y * < 4.0 ) and backward ( − 5.0 < y * < − 2.5 ) rapidity regions at a nucleon-nucleon center-of-mass energy of s NN = 8.16 TeV . The nuclear modification factors of both D s + and D + mesons are determined as a function of transverse momentum, p T , and rapidity. In addition, the D s + to D + cross section ratio is measured as a function of the primary charged particle multiplicity in the event. An enhanced D s + to D + production in high-multiplicity events is observed for the whole measured p T range, in particular at low p T and backward rapidity, where the significance exceeds six standard deviations. This constitutes the first observation of strangeness enhancement in charm quark hadronization in high-multiplicity p Pb collisions. The results are also qualitatively consistent with the presence of quark coalescence as an additional charm quark hadronization mechanism in high-multiplicity proton-lead collisions. © 2024 CERN, for the LHCb Collaboration 2024 CERN

Aaij, R. (ORCID:0000000305331952)↗
DOE OSTI2013

Excited spectroscopy of charmed mesons from lattice QCD

We present spectra of highly excited D and D s mesons up to around 3.8 GeV determined using dynamical lattice QCD. We employ novel computational techniques and the variational method with a large basis of carefully constructed operators in order to extract and reliably identify the continuum spin of an extensive set of excited states. These include states with high spin and states identified as having an explicit gluonic contribution. Calculations were performed on two volumes, both with a pion mass of approximately 400 MeV, achieving a high statistical precision for both ground and excited states. We discuss our results in light of experimental observations, comment on the phenomenological implications and identify the lightest ‘supermultiplet’ of hybrid mesons in each sector.

Physics↗