Measurement of theD*(2010)+Meson Width and theD*(2010

Abstract

We measure the mass difference, ∆m0, between the D * (2010) + and the D 0 and the natural line width, Γ, of the transition D * (2010) + → D 0 π + . The data were recorded with the BABAR detector at center-of-mass energies at and near the Υ (4S) resonance, and correspond to an integrated luminosity of approximately 477 fb −1 . The D 0 is reconstructed in the decay modesFor the decay mode D 0 → K − π + we obtain Γ = (83.4 ± 1.7 ± 1.5) keV and ∆m0 = (145 425.6 ± 0.6 ± 1.8) keV, where the quoted errors are statistical and systematic, respectively. For the D 0 → K − π + π − π + mode we obtain Γ = (83.2 ± 1.5 ± 2.6) keV and ∆m0 = (145 426.6 ± 0.5 ± 2.0) keV. The combined measurements yield Γ = (83.3 ± 1.2 ± 1.4) keV and ∆m0 = (145 425.9 ± 0.4 ± 1.7) keV; the width is a factor of approximately 12 times more precise than the previous value, while the mass difference is a factor of approximately 6 times more precise. PACS numbers: 13.20.Fc, 13.25Ft, 14.40.Lb, 12.38.Gc, 12.38.Qk, 12.39.Ki, 12.39.Pn The line width of the D * (2010) + (D * + ) provides a window into a nonperturbative regime of strong interaction physics where the charm quark is the heavier meson constituent [1][2][3]. The line width provides an experimental test of D meson spectroscopic models, and is related to the strong coupling of the D * Dπ system, g D * Dπ . In the heavy-quark limit, which is not necessarily a good approximation for the charm quark [4], this coupling can be related to the universal coupling of heavy mesons to a pion,ĝ. Since the decay B * → Bπ is kinematically forbidden, it is not possible to measure the coupling g B * Bπ directly. However, the D and B systems can be related throughĝ, allowing the calculation of g B * Bπ , which is needed for a model-independent extraction of |V ub | [5,6] and which forms one of the larger theoretical uncertainties for the determination of |V ub | [7].We study theto extract values of the D * + width Γ and the difference between the D * + and D 0 masses ∆m 0 . Values are reported in natural units and the use of charge conjugate reactions is implied throughout this paper. The only prior measurement of the width is Γ = (96 ± 4 ± 22) keV by the CLEO collaboration, where the uncertainties are statistical and systematic, respectively [8]. In the present analysis, we use a data sample that is approximately 50 times larger. This allows us to apply restrictive selection criteria to reduce background and to investigate sources of systematic uncertainty with high precision.To extract Γ, we fit the distribution of the mass differ-4 ence between the reconstructed D * + and the D 0 masses, ∆m. The signal component is described with a P-wave relativistic Breit-Wigner (RBW) function convolved with a resolution function based on a Geant4 Monte Carlo (MC) simulation of the detector response [9].The full width at half maximum (FWHM) of the RBW line shape (≈ 100 keV) is much less than the FWHM of the almost Gaussian resolution function which describes more than 99% of the signal (≈ 300 keV). Therefore, near the peak, ...

The D∗Dπ and B∗Bπ couplings from light-cone sum rules

“…The PDG average [3] of the two measurements [1,2] of the D * ± -meson total width is Γ tot (D * ± ) = 83.4±1.8 keV 6 and using the precisely measured branching fraction BR(D * → JHEP03(2021)016 Our results on the D * Dπ coupling presented in table 6 are somewhat smaller than the above value, but the difference is not significant. Even if we take the smallest interval predicted from LCSR (the combination of Model 2 with the lattice decay constants) its upper limit is only 10% smaller than the measured strong coupling.…”

“…To this end, we will include the next-to-leading-order (NLO) twist-3 term, calculating the corresponding gluon radiative corrections. We remind that in the LCSRs for the strong couplings the twist-3 part is comparable to the twist-2 part, their ratio being of O(µ π /m Q ), where the chirally enhanced parameter µ π = m 2 π /(m u + m d ) is comparable with the heavy quark mass m Q = m c,b . Hence, by adding the gluon radiative correction to the twist-3 term, we will achieve the same NLO accuracy for both equally important parts of the OPE.…”

“…In the charm sector, the D * Dπ coupling has been measured, combining the branching fractions of the D * → Dπ decays with the total width of D * . The latter is currently available from the two experiments [1][2][3] and has a small error. The B * Bπ coupling cannot be directly measured, due to the lack of phase space for a B * → Bπ decay.…”

Observation of an exotic narrow doubly charmed tetraquark

“…This procedure removes the uncertainty on the δm BW parameter related to imprecise knowledge of the D 0 mass. In contrast, the small uncertainty of 2 keV/c 2 for the known D * + − D 0 mass difference [35,97,98] directly affects the δm BW value and therefore is assigned as the corresponding systematic uncertainty.…”

“…As the mass of the D 0 D 0 π + combinations is calculated with the mass of each D 0 meson constrained to the known value of the D 0 mass, the δm BW parameter is insensitive to the precision of the D 0 mass. However, the small uncertainty of 2 keV/c 2 for the D * + −D 0 mass difference [35,97,98] directly affects the δm BW value. The corresponding systematic uncertainty is added.…”