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Study of $D_{sJ}$ decays to $D^+K^0_{\rm S}$ and $D^0K^+$ final states in $pp$ collisions

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Abstract

A study of $D^+\KS$ and $D^0K^+$ final states is performed in a sample of 1.0/fb of $pp$ collision data collected at a centre-of-mass energy of $\sqrt{s}=7$ TeV with the \lhcb detector. We confirm the existence of the $D_{s1}^*(2700)^+$ and $D_{sJ}^*(2860)^+$ excited states and measure their masses and widths to be {eqnarray} m(D_{s1}^*(2700)^+) &=& 2709.2 \pm 1.9({stat})\pm 4.5({syst}) {MeV}/c^2,\cr \Gamma(D_{s1}^*(2700)^+) &=& 115.8 \pm 7.3({stat}) \pm12.1({syst}) {MeV}/c^2,\cr m(D_{sJ}^*(2860)^+) &=& 2866.1 \pm 1.0({stat}) \pm 6.3({syst}) {MeV}/c^2,\cr \Gamma(D_{sJ}^*(2860)^+) &=& 69.9 \pm 3.2({stat}) \pm 6.6({syst}) {MeV}/c^2.\cr {eqnarray}

Figures and captions

Invariant mass distribution (points) for (a) $D^+$, (b) $D^0$, $ K ^0_{\rm\scriptscriptstyle S} $ decaying (c) inside and (d) outside the vertex detector. We show the total probability density function (solid curve), the signal component as a sum of Gaussian distributions (dotted curve) and a decreasing exponential distribution to describe the background component (dashed curve). The region within the vertical lines corresponds to $\pm3$ standard deviations in mass resolution from the measured peak.

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Invariant mass distributions for (a) $D^+ K ^0_{\rm\scriptscriptstyle S} $ and (b) $D^0K^+$.

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Invariant mass distributions (points) for (a) $D^+ K ^0_{\rm\scriptscriptstyle S} $ and (b) $D^0K^+$. We show the total simultaneous probability density function (solid line), the $D_{s2}^*(2573)^+$ (fine dotted line), $D_{s1}^*(2700)^+$ (dot-dot-dot dashed line), $D_{sJ}^*(2860)^+$ (dot dashed line) and background contribution (dashed line). Invariant mass distributions after combinatorial background subtraction are shown for (c) $D^+ K ^0_{\rm\scriptscriptstyle S} $ and (d) $D^0K^+$, where the vertical scales are truncated to show the $D_{s1}^*(2700)^+$ and $D_{sJ}^*(2860)^+$ signals more clearly.

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Animated gif made out of all figures.

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Tables and captions

Parameters for $D_{s1}^*(2700)^+$ and $D_{sJ}^*(2860)^+$ states, evaluated with binned fits to the samples. Masses and widths are given in units of $ {\mathrm{ Me V /}c^2}$ . Uncertainties are statistical only.

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Total number of events for $D_{s1}^*(2700)^+$ and $D_{sJ}^*(2860)^+$, evaluated with the reference fit. Uncertainties are statistical only.

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Systematic uncertainties for the $D_{s1}^*(2700)^+$ and $D_{sJ}^*(2860)^+$ parameters. Mass and width uncertainties, $\delta m$ and $\delta\Gamma$, are given in units of $ {\mathrm{ Me V /}c^2}$ . The total uncertainties are calculated as the quadratic sums of all contributions.

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Created on 27 April 2024.