The production yields of the orbitally excited charm-strange mesons $\mathrm{D_{s1}(1^{+})(2536)^+}$ and $\mathrm{D_{s2}^{*}(2^{+})(2573)^+}$ 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 $\mathrm{D_{s1}^+}$ and $\mathrm{D_{s2}^{*+}}$ mesons were measured at midrapidity ($|y|<~0.5$) in minimum-bias and high-multiplicity pp collisions in the transverse-momentum interval $2 <~ p_{\rm T} <~ 24$ GeV/$c$. Their production yields relative to the $\mathrm{D_{s}^{+}}$ ground-state yield were found to be compatible between minimum-bias and high-multiplicity collisions, as well as with previous measurements in $\mathrm{e^\pm p}$ and $\mathrm{e^{+}e^{-}}$ collisions. The measured $\mathrm{D_{s1}^+/D_{s}^{+}}$ and $\mathrm{D_{s2}^{*+}/D_{s}^{+}}$ 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.
Submitted to: PRD
e-Print: arXiv:2409.11938 | PDF | inSPIRE
CERN-EP-2024-233
Figure group
Figure 1
Invariant-mass distributions $M(\mathrm{K}\pi\pi {\rm K^0_S}) - M(\mathrm{K}\pi\pi)$ of ${\rm D_{s1}^+}$ (top panels) and ${\rm D_{s2}^{*+}}$ (bottom panels) candidates and charge conjugates in the $2< \pt< 24$ GeV/$c$ interval, for the INEL$>$0 and HMV0 (0-0.1% V0M) samples. The blue solid lines show the total fit functions described in the text, and the red dashed lines represent the combinatorial background. The raw-yield ($S$) values are reported together with their statistical uncertainties, as well as the estimated significance of the signal (Signif.). |     |
Figure 2
${\rm D_{s1}^+}/\Ds$ (left) and ${\rm D_{s2}^{*+}}/\Ds$ (right) ratio times BR as a function of the average charged-particle multiplicity \avdndeta in pp collisions at $\s= 13$ TeV at midrapidity ($|y| < 0.5$). The experimental results are compared with the theoretical predictions based on the SHM, the SHMc, PYTHIA 8, and EPOS4HQ. The statistical and systematic uncertainties on the measured ratios are depicted as vertical lines and boxes, respectively. The theoretical uncertainty on the predicted ratios is depicted as a shaded band for the ${\rm D_{s1}^+}$. |   |
Figure 3
$\pt$-integrated yields of prompt ${\rm D_{s1}^+}$ (left) and ${\rm D_{s2}^{*+}}$ (right) mesons divided by the $\pt$-integrated yields of prompt $\Ds$ mesons. The measurements are compared to the ones performed at LEP. For the ALICE measurements, the results consider the BR of the decay of interest computed as described in the text considering the RQM predictions and PDG information. The experimental results are compared with the theoretical predictions based on the SHM and the SHMc models. |  |