Observation of the B c + Meson in Pb-Pb and p p Collisions at s N N = 5.02 TeV and Measurement of its Nuclear Modification Factor
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
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Results for “charmed mesons”
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Scalar and Tensor Charmonium Resonances in Coupled-Channel Scattering from Lattice QCD
We determine J P C = 0 + + and 2 + + hadron-hadron scattering amplitudes in the charmonium energy region up to 4100 MeV using lattice QCD, a first-principles approach to QCD. Working at m π ≈ 391 MeV , more than 200 finite-volume energy levels are computed and these are used in extensions of the Lüscher formalism to determine infinite-volume coupled-channel scattering amplitudes. We find that this energy region contains a single χ c 0 and a single χ c 2 resonance. Both are found as pole singularities on the closest unphysical Riemann sheet, just below 4000 MeV with widths around 70 MeV. The largest couplings are to kinematically closed D * D ¯ * channels in S -wave, and couplings to several decay channels consisting of pairs of open-charm mesons are found to be large and significant in both cases. Above the ground state χ c 0 , no other scalar bound states or near- D D ¯ threshold resonances are found, in contrast to several theoretical and experimental studies. Published by the American Physical Society 2024
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
A general-mass scheme for prompt charm production at hadron colliders
In these proceedings, we apply the recently developed S-ACOT-MPS factorization scheme at the next-to-leading order to prompt charm production at hadron colliders. It provides a good agreement with experimental data on charm meson production measured by LHCb at 7 and 13 TeV. The low- p_T p T data are on the margins of the theoretical error bands, emphasizing the importance of including contributions beyond the next-to-leading order.
Xie, Keping↗
A general-mass scheme for prompt charm production at hadron colliders
In these proceedings, we apply the recently developed S-ACOT-MPS factorization scheme at the next-to-leading order to prompt charm production at hadron colliders. It provides a good agreement with experimental data on charm meson production measured by LHCb at 7 and 13 TeV. The low-$p_T$ data are on the margins of the theoretical error bands, emphasizing the importance of including contributions beyond the next-to-leading order.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Studying the interaction between charm and light-flavor mesons
The two-particle momentum correlation functions between charm mesons ( D * ± and D ± ) and charged light-flavor mesons ( π ± and K ± ) in all charge combinations are measured for the first time by the ALICE Collaboration in high-multiplicity proton–proton collisions at a center-of-mass energy of s = 13 TeV . For DK and D * K pairs, the experimental results are in agreement with theoretical predictions of the residual strong interaction based on quantum chromodynamics calculations on the lattice and chiral effective field theory. In the case of D π and D * π pairs, tension between the calculations including strong interactions and the measurement is observed. For all particle pairs, the data can be adequately described by Coulomb interaction only, indicating a shallow interaction between charm and light-flavor mesons. Finally, the scattering lengths governing the residual strong interaction of the D π and D * π systems are determined by fitting the experimental correlation functions with a model that employs a Gaussian potential. The extracted values are small and compatible with zero. © 2024 CERN, for the ALICE Collaboration 2024 CERN
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
The role of charm and unflavored mesons in prompt atmospheric lepton fluxes
The all-sky very-high-energy (10 4 − 10 6 GeV) atmospheric muon flux measured by IceCube shows a spectral hardening at the highest energies, indicating the presence of a prompt component. IceCube has also measured the atmospheric muon neutrino flux at high energy. However, since this flux is dominated by astrophysical neutrinos, only an upper bound can be placed on the prompt atmospheric ν μ + $\overline{ν}$ μ contribution. In this work, we provide a new evaluation of the prompt atmospheric muon flux including an intrinsic charm component in the cosmic ray-air interactions. The latter enhances the forward production of $\overline{D}$ 0 , D – and Λc, which subsequently decay into final states containing muons and muon neutrinos. We show how the increase in the prompt muon flux due to intrinsic charm is accompanied by a corresponding enhancement in the prompt muon neutrino flux. We implement different intrinsic charm production models in MCEq to calculate the resulting lepton fluxes. We discuss the challenges of achieving predictions that are simultaneously consistent with both IceCube’s high-energy atmospheric muon flux measurements and IceCube upper bounds on the prompt muon neutrino flux, and we quantify the resulting discrepancies. As possible solutions, we explore scaling of the unflavored meson contributions to the prompt atmospheric muon flux to assess how such adjustments can reconcile these differences. The tensions emphasized in our work call for a refinement of the hadronic interaction models, especially the production of unflavored mesons, and for new experimental data sensitive to unflavored meson and heavy flavor production with reliable estimates of the associated uncertainties. We suggest that the energy and zenith angle dependence of muon and neutrino flux ratios from future neutrino telescope measurements may help to disentangle different scenarios.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of the relative B c ± / B ± production cross section with the ATLAS detector at s = 8 TeV
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Observation of a multiplicity dependence in the $\mathcal{p}_T$-differential charm baryon-to-meson ratios in proton–proton collisions at $\sqrt{s}$ = 13 TeV
The production of prompt D 0 , D$^+_s$, and Λ$^+_c$ hadrons, and their ratios, D$^+_s$/D 0 and Λ$^+_c$/D 0 , are measured in proton–proton collisions at $\sqrt{s}$ = 13 TeV at midrapidity (|y| < 0.5) with the ALICE detector at the LHC. The measurements are performed as a function of the charm-hadron transverse momentum (p T ) in intervals of charged-particle multiplicity, measured with two multiplicity estimators covering different pseudorapidity regions. While the strange to non-strange D$^+_s$/D 0 ratio indicates no significant multiplicity dependence, the baryon-to-meson p T -differential Λ$^+_c$/D 0 ratio shows a multiplicity-dependent enhancement, with a significance of 5.3σ for 1 < p T < 12 GeV/c, comparing the highest multiplicity interval with respect to the lowest one. The measurements are compared with a theoretical model that explains the multiplicity dependence by a canonical treatment of quantum charges in the statistical hadronisation approach, and with predictions from event generators that implement colour reconnection mechanisms beyond the leading colour approximation to model the hadronisation process. The Λ$^+_c$/D 0 ratios as a function of p T present a similar shape and magnitude as the Λ/K$^0_s$ ratios in comparable multiplicity intervals, suggesting a potential common mechanism for light- and charm-hadron formation, with analogous multiplicity dependence. The p T -integrated ratios, extrapolated down to p T = 0, do not show a significant dependence on multiplicity within the uncertainties.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
First measurement of 𝐷 𝑠1 (1 + )(2536) + and 𝐷$^{*}_{𝑠2}$(2 + )(2573) + production in proton-proton collisions at $\sqrt{s}$ = 13 TeV at the LHC
The production yields of the orbitally excited charm-strange mesons D s1 (1 + )(2536)+ and 𝐷$^{*}_{𝑠2}$(2 + )(2573) + were measured for the first time in proton-proton (pp) collisions at a center-of-mass energy of $\sqrt{s}$ =13 TeV with the ALICE experiment at the LHC. The D$^{+}_{s1}$ and D$^{*+}_{s2}$ mesons were measured at midrapidity (|𝑦| < 0.5) in minimum-bias and high-multiplicity pp collisions in the transverse-momentum interval 2< 𝑝 T < 24 GeV/𝑐. Their production yields relative to the D$^{+}_{s}$ ground-state yield were found to be compatible between minimum-bias and high-multiplicity collisions, as well as with previous measurements in e ± p and e + e − collisions. The measured D$^{+}_{s1}$/D$^{+}_{s}$ and D$^{*+}_{s2}$/D$^{+}_{s}$ yield ratios are described by statistical hadronization models and can be used to tune the parameters governing the production of excited charm-strange hadrons in Monte Carlo generators, such as pythia 8.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Measurement of the production of charm jets tagged with D0 mesons in pp collisions at $\sqrt{s}$ = 5.02 and 13 TeV
The measurement of the production of charm jets, identified by the presence of a D 0 meson in the jet constituents, is presented in proton–proton collisions at centre-of-mass energies of $\sqrt{s}$= 5.02 and 13 TeV with the ALICE detector at the CERN LHC. The D 0 mesons were reconstructed from their hadronic decay D 0 → K – π + and the respective charge conjugate. Jets were reconstructed from D 0 -meson candidates and charged particles using the anti-k T algorithm, in the jet transverse momentum range 5 < p T,chjet < 50 GeV/c, pseudorapidity |η jet | < 0.9 – R, and with the jet resolution parameters R = 0.2, 0.4, 0.6. The distribution of the jet momentum fraction carried by a D 0 meson along the jet axis $\left({z}_{\Big\Vert}^{\textrm{ch}}\right)$ was measured in the range 0.4 < ${z}_{\Big\Vert}^{\textrm{ch}}$ < 1.0 in four ranges of the jet transverse momentum. Comparisons of results for different collision energies and jet resolution parameters are also presented. The measurements are compared to predictions from Monte Carlo event generators based on leading-order and next-to-leading-order perturbative quantum chromodynamics calculations. A generally good description of the main features of the data is obtained in spite of a few discrepancies at low p T,chjet . Measurements were also done for R = 0.3 at $\sqrt{s}$= 5.02 and are shown along with their comparisons to theoretical predictions in an appendix to this paper.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for the Rare Decay 𝐷 0 → 𝜇 + 𝜇 − in Proton-Proton Collisions at $\sqrt{s}$ = 13.6 TeV
A search for the rare decay 𝐷 0 → 𝜇 + 𝜇 − is reported using proton-proton collision events at $\sqrt{s}$ =13.6 TeV collected by the CMS detector in 2022–2023, corresponding to an integrated luminosity of 64.5 fb −1 . This is the first analysis to use a newly developed inclusive dimuon trigger, expanding the scope of the CMS flavor physics program. The search uses 𝐷 0 mesons obtained from 𝐷* + → 𝐷 0 𝜋 + decays. No significant excess is observed. A limit on the branching fraction of ℬ(𝐷 0 → 𝜇 + 𝜇 − ) < 2.4 × 10 −9 at 95% confidence level is set. This is the most stringent upper limit set on any flavor changing neutral current decay in the charm sector.
Charmed mesons↗
Observation of a New Excited D s + Meson in B 0 → D − D + K + π − Decays
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for Rare or Forbidden Decays of the D 0 Meson
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurements of the absolute branching fractions of hadronic D -meson decays involving kaons and pions
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Study of light scalar mesons through D s + → π 0 π 0 e + ν e and K S 0 K S 0 e + ν e decays
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Model-independent measurement of 𝐷 0 −$\overline{D}$ 0 mixing parameters in 𝐷 0 → 𝐾$^{0}_{𝑆}$𝜋 + 𝜋 − decays at Belle and Belle II
We perform a model-independent measurement of the 𝐷 0 −$\overline{D}$ 0 mixing parameters using samples of 𝑒 + 𝑒 − -collision data collected by the Belle and Belle II experiments that have integrated luminosities of 951 fb −1 and 408 fb −1 , respectively. Approximately 2.05 × 10 6 neutral 𝐷 mesons are reconstructed in the 𝐷 0 → 𝐾$^{0}_{S}$𝜋 + 𝜋 − channel, with the neutral 𝐷 flavor tagged by the charge of the pion in the 𝐷* + → 𝐷 0 𝜋 + decay. Assuming charge-parity symmetry, the mixing parameters are measured to be 𝑥 = (4.0 ±1.7 ±0.4) × 10 −3 and 𝑦 = (2.9 ±1.4 ±0.3) × 10 −3 , where the first uncertainties are statistical and the second systematic. The results are consistent with previous determinations.
Charmed mesons↗
Measurement of the time-integrated 𝐶𝑃 asymmetry in 𝐷 0 → 𝐾$^{0}_{S}$𝐾$^{0}_{S}$ decays using opposite-side flavor tagging at Belle and Belle II
We measure the time-integrated 𝐶𝑃 asymmetry in 𝐷 0 → 𝐾$^{0}_{S}$𝐾$^{0}_{S}$ decays reconstructed in 𝑒 + 𝑒 − → $c\bar{c}$ events collected by the Belle and Belle II experiments. The corresponding data samples have integrated luminosities of 980 and 428 fb −1 , respectively. To infer the flavor of the 𝐷 0 meson, we exploit the correlation between the flavor of the reconstructed decay and the electric charges of particles reconstructed in the rest of the 𝑒 + 𝑒 − → $c\bar{c}$ event. This results in a sample which is independent from any other previously used at Belle or Belle II. The result, 𝐴 𝐶𝑃 (𝐷 0 → 𝐾$^{0}_{S}$𝐾$^{0}_{S}$)=(1.3±2.0±0.2)%, where the first uncertainty is statistical and the second systematic, is consistent with previous determinations and with 𝐶𝑃 symmetry.
CP violation↗
Multiplicity dependent 𝐽/𝜓 and 𝜓(2𝑆) production at forward and backward rapidity in 𝑝 + 𝑝 collisions at $\sqrt{𝑠}$ = 200 GeV
Recent measurements of 𝐽/𝜓 production as a function of event charged-particle multiplicity at the collision energies of both the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) show enhanced 𝐽/𝜓 production yields with increasing multiplicity. One potential explanation for this type of dependence is multiparton interactions (MPI). We present the first study of potential autocorrelations at RHIC energies and forward and backward rapidity of self-normalized 𝐽/𝜓 yields and 𝜓(2𝑆) to 𝐽/𝜓 ratio, as a function of self-normalized multiplicity in 𝑝 + 𝑝 collisions. In addition, detailed pythia studies tuned to RHIC energies were performed to investigate the MPI impacts. We find that the PHENIX data at RHIC are consistent with recent LHC measurements and can only be described by pythia calculations that include MPI effects. The forward and backward 𝜓(2𝑆) to 𝐽/𝜓 ratio is found to be less dependent on the charged-particle multiplicity.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗