# Study of $D^{(*)+}_{sJ}$ mesons decaying to $D^{*+} K^0_{\rm S}$ and $D^{*0} K^+$ final states

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## Abstract

A search is performed for $D^{(*)+}_{sJ}$ mesons in the reactions $pp \to D^{*+} K^0_{\rm S} X$ and $pp \to D^{*0} K^+ X$ using data collected at centre-of-mass energies of 7 and 8 TeV with the LHCb detector. For the $D^{*+} K^0_{\rm S}$ final state, the decays $D^{*+} \to D^0 \pi^+$ with $D^0 \to K^- \pi^+$ and $D^0 \to K^- \pi^+ \pi^+ \pi^-$ are used. For $D^{*0} K^+$, the decay $D^{*0} \to D^0 \pi^0$ with $D^0 \to K^- \pi^+$ is used. A prominent $D_{s1}(2536)^+$ signal is observed in both $D^{*+} K^0_{\rm S}$ and $D^{*0} K^+$ final states. The resonances $D^*_{s1}(2700)^+$ and $D^*_{s3}(2860)^+$ are also observed, yielding information on their properties, including spin-parity assignments. The decay $D^*_{s2}(2573)^+ \to D^{*+} K^0_{\rm S}$ is observed for the first time, at a significance of 6.9 $\sigma$, and its branching fraction relative to the $D^*_{s2}(2573)^+ \to D^+ K^0_{\rm S}$ decay mode is measured.

## Figures and captions

 Distributions of $D ^0 \pi ^+$ invariant mass for (a) $D ^0 \rightarrow K ^- \pi ^+$ and (b) $D ^0 \rightarrow K ^- \pi ^+ \pi ^+ \pi ^-$ . $\pi ^+ \pi ^-$ mass spectrum for (c) long and (d) downstream $K ^0_{\mathrm{ \scriptscriptstyle S}}$ . The full (red) lines describe the fitting function. The dashed lines show the background contributions and the vertical dotted lines indicate the signal regions. fig1a.pdf [20 KiB] HiDef png [219 KiB] Thumbnail [179 KiB] *.C file fig1b.pdf [20 KiB] HiDef png [212 KiB] Thumbnail [173 KiB] *.C file fig1c.pdf [17 KiB] HiDef png [186 KiB] Thumbnail [151 KiB] *.C file fig1d.pdf [19 KiB] HiDef png [204 KiB] Thumbnail [169 KiB] *.C file Distribution of $\Delta m( D ^0 \pi ^0 )$ invariant mass. The full (red) line describes the fitting function. The dashed line shows the background contribution and the dotted vertical lines define the $D^{*0}$ signal region. fig2.pdf [16 KiB] HiDef png [165 KiB] Thumbnail [138 KiB] *.C file Distribution of the $D ^{*+} K ^0_{\mathrm{ \scriptscriptstyle S}}$ invariant mass for $D ^0 \rightarrow K ^- \pi ^+$ decay. The full (red) line describes the fitting function. The dashed line displays the fitted background and the dotted lines the $D_{s1}(2536)^{+}$ , $D^*_{s2}(2573)^{+}$ , $D^*_{s1}(2700)^+$ , $D_{sJ}^{*}(2860)^+$ and $D_{sJ}(3040)^+$ contributions. The inset displays the $D ^{*+} K ^0_{\mathrm{ \scriptscriptstyle S}}$ mass spectrum after subtracting the fitted background. fig3.pdf [40 KiB] HiDef png [287 KiB] Thumbnail [229 KiB] *.C file Mass spectrum of $D ^{*+} K ^0_{\mathrm{ \scriptscriptstyle S}}$ candidates for $D ^0 \rightarrow K ^- \pi ^+$ in (a) the NP sample, and (b) the UP sample. The full (red) lines describe the fitting function. The dashed lines show the fitted background and the dotted lines the $D^*_{s2}(2573)^{+}$ , $D^*_{s1}(2700)^+$ , $D_{sJ}^{*}(2860)^+$ and $D_{sJ}(3040)^+$ contributions. The insets display the $D ^{*+} K ^0_{\mathrm{ \scriptscriptstyle S}}$ mass spectrum after subtracting the fitted background. fig4a.pdf [44 KiB] HiDef png [305 KiB] Thumbnail [243 KiB] *.C file fig4b.pdf [43 KiB] HiDef png [287 KiB] Thumbnail [238 KiB] *.C file Mass spectrum of (a) $D ^{*+} K ^0_{\mathrm{ \scriptscriptstyle S}}$ candidates for $D ^0 \rightarrow K ^- \pi ^+ \pi ^+ \pi ^-$ , and (b) $D ^{*0} K ^+$ candidates for the NP sample. The full (red) lines describe the fitting function. The dashed lines show the fitted background and the dotted lines the $D^*_{s2}(2573)^{+}$ , $D^*_{s1}(2700)^+$ , $D_{sJ}^{*}(2860)^+$ and $D_{sJ}(3040)^+$ contributions. The insets display the $D ^{*+} K ^0_{\mathrm{ \scriptscriptstyle S}}$ and $D ^{*0} K ^+$ mass spectra after subtracting the fitted background. fig5a.pdf [45 KiB] HiDef png [340 KiB] Thumbnail [293 KiB] *.C file fig5b.pdf [43 KiB] HiDef png [323 KiB] Thumbnail [276 KiB] *.C file Distribution of the invariant mass of $D ^+ K ^0_{\mathrm{ \scriptscriptstyle S}}$ candidates from Ref. [10]. The full (red) line is the result from the fit described in the text. The dashed line indicates the fitted background and the dotted line shows the fitted $D^*_{s2}(2573)^{+}$ contribution. fig6.pdf [28 KiB] HiDef png [208 KiB] Thumbnail [156 KiB] *.C file Mass spectra, in the $D_{s1}(2536)^{+}$ mass region, for the NP sample of (a) $D ^{*+} K ^0_{\mathrm{ \scriptscriptstyle S}}$ with $D ^0 \rightarrow K ^- \pi ^+$ , (b) $D ^{*+} K ^0_{\mathrm{ \scriptscriptstyle S}}$ with $D ^0 \rightarrow K ^- \pi ^+ \pi ^+ \pi ^-$ , and (c) $D ^{*0} K ^+$ final states. The full (red) lines describe the fitting function. The dashed lines show the fitted background and the dotted lines the $D^*_{s2}(2573)^{+}$ contributions. The insets display the $D ^* K$ mass spectra after subtracting the fitted background. fig7a.pdf [25 KiB] HiDef png [228 KiB] Thumbnail [186 KiB] *.C file fig7b.pdf [26 KiB] HiDef png [235 KiB] Thumbnail [192 KiB] *.C file fig7c.pdf [24 KiB] HiDef png [215 KiB] Thumbnail [174 KiB] *.C file Distributions of the measured signal yields for (a) $D_{s1}(2536)^{+}$ and (b) $D^*_{s2}(2573)^{+}$ as a function of the helicity angle $\cos\theta_{\rm H}$ . The distributions are fitted with UP (a) and NP (b) functions. fig8a.pdf [14 KiB] HiDef png [156 KiB] Thumbnail [136 KiB] *.C file fig8b.pdf [14 KiB] HiDef png [163 KiB] Thumbnail [143 KiB] *.C file Distributions of the measured signal yields for (a) $D^*_{s1}(2700)^+$ , (b) $D_{sJ}^{*}(2860)^+$ and (c) $D_{sJ}(3040)^+$ as a function of the helicity angle $\cos\theta_{\rm H}$ . The distributions are fitted with NP (a,b) and UP (c) functions. fig9a.pdf [15 KiB] HiDef png [171 KiB] Thumbnail [153 KiB] *.C file fig9b.pdf [15 KiB] HiDef png [187 KiB] Thumbnail [174 KiB] *.C file fig9c.pdf [15 KiB] HiDef png [162 KiB] Thumbnail [143 KiB] *.C file Animated gif made out of all figures. PAPER-2015-052.gif Thumbnail

## Tables and captions

 Results from the fits to the $D ^{*+} K ^0_{\mathrm{ \scriptscriptstyle S}}$ and $D ^{*0} K ^+$ mass spectra. Resonances parameters are expressed in $\mathrm{ Me V}$ . When two uncertainties are presented, the first is statistical and the second systematic. The symbol ndf indicates the number of degrees of freedom. Table_1.pdf [64 KiB] HiDef png [137 KiB] Thumbnail [64 KiB] tex code Contributions (in $\mathrm{ Me V}$ ) to the systematic uncertainties on the $D^*_{s1}(2700)^+$ and $D_{sJ}^{*}(2860)^+$ resonances parameters. Table_2.pdf [46 KiB] HiDef png [37 KiB] Thumbnail [16 KiB] tex code Results from the fits to the $D ^+ K ^0_{\mathrm{ \scriptscriptstyle S}}$ and $D ^{*+} K ^0_{\mathrm{ \scriptscriptstyle S}}$ mass spectra for the evaluation of the $D^*_{s2}(2573)^{+} \rightarrow D ^{*+} K ^0_{\mathrm{ \scriptscriptstyle S}}$ relative branching fraction. Table_3.pdf [62 KiB] HiDef png [68 KiB] Thumbnail [32 KiB] tex code Measurements used to evaluate the $D^*_{s2}(2573)^{+}$ relative branching fraction $\cal B ( D^*_{s2}(2573)^{+} \rightarrow D ^{*+} K ^0_{\mathrm{ \scriptscriptstyle S}} )/\cal B ( D^*_{s2}(2573)^{+} \rightarrow D ^+ K ^0_{\mathrm{ \scriptscriptstyle S}} )$. Table_4.pdf [61 KiB] HiDef png [36 KiB] Thumbnail [14 KiB] tex code Relative systematic uncertainties in the evaluation of the ratio of branching fractions $\cal R$ . Table_5.pdf [47 KiB] HiDef png [53 KiB] Thumbnail [23 KiB] tex code Values of $\chi^2/{\rm ndf}$ from the fits to the helicity angles distributions. Table_6.pdf [46 KiB] HiDef png [86 KiB] Thumbnail [41 KiB] tex code

Created on 11 July 2020.