Observation of a new excited $D_s^+$ meson in $B^0$ to $D^- D^+ K^+ \pi^-$ decays

Information

LHCb-PAPER-2020-034
CERN-EP-2020-203
arXiv:2011.09112 [PDF]

(Submitted on 18 Nov 2020)
Phys. Rev. Lett. 126 (2021) 122002
Inspire 1831034

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Abstract

Using $pp$ collision data corresponding to an integrated luminosity of $5.4 {\rm fb}^{-1}$ collected with the LHCb detector at a center-of-mass energy of $13 {\rm TeV}$, the $B^0\to D^-D^+K^+\pi^-$ decay is studied. A new excited $D_s^+$ meson is observed decaying into the $D^+K^+\pi^-$ final state with large statistical significance. The pole mass and width, and the spin-parity of the new state are measured with an amplitude analysis to be $m_R=2591\pm6\pm7 {\rm MeV}$, $\Gamma_R=89\pm16\pm12 {\rm MeV}$ and $J^P=0^-$, where the first uncertainty is statistical and the second systematic. Fit fractions for all components in the amplitude analysis are also reported. The new resonance, denoted as $D_{s0}(2590)^+$, is a strong candidate to be the $D_s(2^1{S}_0)^+$ state, the radial excitation of the pseudoscalar ground-state $D_s^+$ meson.

Figures and captions

Mass distribution of the selected $ B ^0$ candidates in the low $ K ^+$ $\pi ^-$ mass region. The fit result is overlaid.	Fig1.pdf [21 KiB] HiDef png [251 KiB] Thumbnail [207 KiB] *.C file
Dalitz plot of the $ D ^+ D ^- $ versus $ D ^+ K ^+ \pi ^- $ masses-squared for $ B ^0$ candidates with masses within $\pm20\text{ Me V} $ around the known $ B ^0$ mass [10] in the low $ K ^+ \pi ^- $ mass region.	Fig2.pdf [25 KiB] HiDef png [250 KiB] Thumbnail [182 KiB] *.C file
Mass projections of (a) $ D ^+ K ^+ \pi ^- $ , (b) $ K ^+ \pi ^- $ , (c) $ D ^+$ $ D ^-$ and (d) $ D ^+$ $\pi ^-$ systems. Data points are shown in black with the background subtracted statistically using the sPlot method [40]. Results of the fit with the $ D _{s0}(2590)^+$ ($J^P=0^-$) model are overlaid as a solid red histogram, and individual contributions shown as dotted histograms.	Fig3a.pdf [33 KiB] HiDef png [347 KiB] Thumbnail [276 KiB] *.C file
	Fig3b.pdf [18 KiB] HiDef png [245 KiB] Thumbnail [203 KiB] *.C file
	Fig3c.pdf [31 KiB] HiDef png [321 KiB] Thumbnail [250 KiB] *.C file
	Fig3d.pdf [30 KiB] HiDef png [283 KiB] Thumbnail [215 KiB] *.C file
Comparison of $\cos \theta_{D_s}$ distributions for the spin parity of the $ D _{s0}(2590)^+$ state assumed to be (a) $0^-$, (b) $1^+$, and (c) $2^-$. The $J^P=0^-$ model is the most consistent with data. Data points are shown in black with the background subtracted statistically using the sPlot method [40]. Fit results are overlaid as a solid red histogram, with individual contributions shown as dotted histograms.	Fig4a.pdf [17 KiB] HiDef png [260 KiB] Thumbnail [219 KiB] *.C file
	Fig4b.pdf [17 KiB] HiDef png [222 KiB] Thumbnail [178 KiB] *.C file
	Fig4c.pdf [17 KiB] HiDef png [226 KiB] Thumbnail [178 KiB] *.C file
Animated gif made out of all figures.	PAPER-2020-034.gif Thumbnail

Tables and captions

Fit fractions for the three $ D ^+_ s $ components in the low $ K ^+$ $\pi ^-$ mass region ( $ {m_{ K ^+ \pi ^- }} <0.75\text{ Ge V} $). The interference fraction between the $ D _{s0}(2590)^+$ and NR components is denoted as $ { D _{s0}^+}$ -NR. There is no net interference between any other pair of components due to the orthogonality of the Wigner small-$d$ matrices for different spins. $ { D _{s1}^+}$ / $ { D _{s0}^+}$ denotes the ratio of the $ D _{s1}(2536)^+$ and $ D _{s0}(2590)^+$ fit fractions.	Table_1.pdf [67 KiB] HiDef png [79 KiB] Thumbnail [38 KiB] tex code
Systematic uncertainties on the pole mass and width of the $ D _{s0}(2590)^+$ state, and fit fractions of the three $ D ^+_ s $ components. The individual sources are added in quadrature to obtain the total uncertainty. The notations are the same as these in Table 1.	Table_2.pdf [74 KiB] HiDef png [82 KiB] Thumbnail [37 KiB] tex code

Supplementary Material [file]

Supplementary material full pdf	supple[..].pdf [387 KiB]
This ZIP file contains supplemetary material for the publication LHCb-PAPER-2020-034. The files are: supplementary.pdf : An overview of the extra figures *.pdf : The figures in pdf format	Fig1.pdf [15 KiB] HiDef png [173 KiB] Thumbnail [154 KiB] *C file
	Fig2a.pdf [31 KiB] HiDef png [357 KiB] Thumbnail [288 KiB] *C file
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	Fig2c.pdf [29 KiB] HiDef png [277 KiB] Thumbnail [215 KiB] *C file
	Fig3a.pdf [31 KiB] HiDef png [311 KiB] Thumbnail [259 KiB] *C file
	Fig3b.pdf [16 KiB] HiDef png [284 KiB] Thumbnail [223 KiB] *C file
	Fig3c.pdf [27 KiB] HiDef png [304 KiB] Thumbnail [244 KiB] *C file
	Fig3d.pdf [27 KiB] HiDef png [261 KiB] Thumbnail [211 KiB] *C file
	Fig3e.pdf [16 KiB] HiDef png [273 KiB] Thumbnail [203 KiB] *C file