First measurement of $\rm Ω_c^0$ production in pp collisions at $\sqrt{s}=13$ TeV

The inclusive production of the charm-strange baryon $\rm \Omega_c^0$ is measured for the first time via its hadronic decay into $\rm \Omega^-\pi^+$ at midrapidity ($|y|<~0.5$) in proton-proton (pp) collisions at the centre-of-mass energy $\sqrt{s}=13$ TeV with the ALICE detector at the LHC. The transverse momentum ($p_{\rm T}$) differential cross section multiplied by the branching ratio is presented in the interval $2<~p_{\rm T}<~12~{\rm GeV}/c$. The $p_{\rm T}$ dependence of the $\rm \Omega_c^0$-baryon production relative to the prompt $\rm D^0$-meson and to the prompt $\rm \Xi_c^0$-baryon production is compared to various models that take different hadronisation mechanisms into consideration. In the measured $p_{\rm T}$ interval, the ratio of the $p_{\rm T}$-integrated cross sections of $\rm \Omega_c^0$ and prompt $\Lambda_{\rm c}^{+}$ baryons multiplied by the $\rm \Omega^-\pi^+$ branching ratio is found to be larger by a factor of about 20 with a significance of about 4$\sigma$ when compared to $\rm e^+e^-$ collisions.

 

Submitted to: PLB
e-Print: arXiv:2205.13993 | PDF | inSPIRE
CERN-EP-2022-106
Figure group

Figure 1

(Left panel): invariant-mass distribution of $\rm \Omega_c^0\rightarrow\Omega^-\pi^+$ candidates and their charge conjugates integrated over the whole \pt interval 2--12 GeV$/c$. The blue line shows the total fit function and the red line represents the combinatorial background fit. (Right panel): acceptance-times-efficiency for prompt, feed-down, and inclusive $\rm \Omega_c^0$ baryons decaying into $\rm \Omega^-\pi^+$ as a function of $p_{\rm T}$ in pp collisions at $\sqrt{s}=13$~TeV.

Figure 2

The pT-differential production cross section of inclusive Ω0 c baryons multiplied by the branching ratio into Ω−π+ for |y| < 0.5 in pp collisions at √s = 13 TeV. The error bars and empty boxes represent the statistical and systematic uncertainties, respectively. The measurement is compared with PYTHIA 8.243 with Monash tune [19] and with CR beyond the leading-colour approximation [9], which are multiplied by a theoretical BR(Ω0 c → Ω−π+) = (0.51+2.19 −0.31)% [42–46].

Figure 3

Left, top panel: ratio of the pT-differential cross section of Ω0 c baryons (multiplied by the branching ratio into Ω−π+) to the D0-meson one [3] in |y| < 0.5 in pp collisions at √s = 13 TeV. Right, top panel: ratio of the pT-differential cross section of Ω0 c baryons (multiplied by the branching ratio into Ω−π+) to the Ξ0 c -baryon one [5] in |y| < 0.5 in pp collisions at √s = 13 TeV. Bottom panels: ratio of the data and models to the Catania (coalescence plus fragmentation) model [10]. The error bars and empty boxes represent the statistical and systematic uncertainties, respectively. The measurements are compared with model calculations (see text for details), which are multiplied by a theoretical BR(Ω0 c → Ω−π+) = (0.51+2.19 −0.31)% [42–46]