$\rm \Lambda_{c}^{+}$ production and baryon-to-meson ratios in pp and p-Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV at the LHC

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.Lett. 127 (2021) 202301, 2021.
Inspire Record 1829739 DOI 10.17182/hepdata.114213

The prompt production of the charm baryon $\rm \Lambda_{c}^{+}$ and the $\rm \Lambda_{c}^{+}/\mathrm {D^0}$ production ratios were measured at midrapidity with the ALICE detector in pp and p-Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$TeV. These new measurements show a clear decrease of the $\rm \Lambda_{c}^{+}/\mathrm {D^0}$ ratio with increasing transverse momentum ($p_{\rm T}$) in both collision systems in the range $2<p_{\rm T}<12$ GeV/$c$, exhibiting similarities with the light-flavour baryon-to-meson ratios ${\rm p}/\pi$ and $\Lambda/\mathrm {K^0_S}$. At low $p_{\rm T}$, predictions that include additional colour-reconnection mechanisms beyond the leading-colour approximation; assume the existence of additional higher-mass charm-baryon states; or include hadronisation via coalescence can describe the data, while predictions driven by charm-quark fragmentation processes measured in $\mathrm {e^+e^-}$ and $\mathrm {e^-p}$ collisions significantly underestimate the data. The results presented in this letter provide significant evidence that the established assumption of universality (colliding-system independence) of parton-to-hadron fragmentation is not sufficient to describe charm-baryon production in hadronic collisions at LHC energies.

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Backward Resonance Production in pi- p --> n pi+ pi- at 8-GeV/c

Eisenstein, Bob I. ; Elliott, J. ; Mollet, W. ; et al.
Phys.Rev.D 18 (1978) 1370-1381, 1978.
Inspire Record 136306 DOI 10.17182/hepdata.24374

We have studied backward meson and baryon production in π−p→nπ+π− at 8 GeV/c using a streamer chamber triggered by the detection of the interaction of the neutron in thick-plate optical spark chambers. Our data sample of 866 events is dominated by the quasi-two-body final states Δ−(1232)π+, nρ0, and nf0. We study the differential and total backward cross sections for these states and the decay angular distributions of the resonances. The results for the Δ− and ρ0 indicate that both nucleon and Δ exchange in the u channel are important in their production, while f0 production is, as expected, consistent with nucleon exchange.

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Correlated production of p and anti-p in Au + Au collisions at s(NN)**(1/2) = 200-GeV.

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Lett.B 649 (2007) 359-369, 2007.
Inspire Record 731666 DOI 10.17182/hepdata.143520

Correlations between p and pbar's at transverse momenta typical of enhanced baryon production in Au+Au collisions are reported. The PHENIX experiment measures same and opposite sign baryon pairs in Au+Au collisions at sqrt(s_NN) = 200 GeV. Correlated production of p and p^bar with the trigger particle from the range 2.5 < p_T < 4.0 GeV/c and the associated particle with 1.8 < p_T < 2.5 GeV/c is observed to be nearly independent of the centrality of the collisions. Same sign pairs show no correlation at any centrality. The conditional yield of mesons triggered by baryons (and anti-baryons) and mesons in the same pT range rises with increasing centrality, except for the most central collisions, where baryons show a significantly smaller number of associated mesons. These data are consistent with a picture in which hard scattered partons produce correlated p and p^bar in the p_T region of the baryon excess.

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Determination of the total c anti-c production cross section in 340-GeV/c Sigma- nucleus interactions.

The WA89 collaboration Adamovich, M.I. ; Alexandrov, Yu.A. ; Barberis, D. ; et al.
Eur.Phys.J.C 13 (2000) 247-254, 2000.
Inspire Record 506075 DOI 10.17182/hepdata.43334

The production of charmed particles by Sigma- of 340 Gev/c momentum was studied in the hyperon beam experiment WA89 at the CERN-SPS, using the Omega-spectrometer. In two data-taking periods in 1993 and 1994 an integrated luminosity of 1600 microb^-1 on copper and carbon targets was recorded. From the reconstruction of 930 +- 90 charm particle decays in 10 decay channels production cross sections for D, antiD, Ds and Lambdac were determined in the region xF>0. Assuming an A^1 dependence of the cross section on the nucleon number, we calculate a total ccbar production cross section of sigma(x_F > 0) = 5.3+- 0.4(stat)+-1.0(syst)+1.0(Xi_c) microb per nucleon. The last term is an upper limit on the unknown contribution from charmed-strange baryon production.

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Enhancement of strange and multi-strange baryons and anti-baryons in S W interactions at 200-GeV/c.

The WA85 collaboration Antinori, F. ; Barnes, R.P. ; Bayes, A.C. ; et al.
Phys.Lett.B 447 (1999) 178-182, 1999.
Inspire Record 500180 DOI 10.17182/hepdata.28123

Strange and multistrange baryon production is expected to be enhanced in heavy ion interactions if a phase transition from hadronic matter to a Quark-Gluon Plasma takes place. The production yields of Λ s, Λ s, Ξ − s, and Ξ + s relative to the production of negative particles are presented for sulphur-tungsten interactions at 200 GeV/ c per nucleon. These production yields are compared to those produced in proton-tungsten interactions and the enhancements of strange and multistrange baryons and antibaryons are presented.

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First measurement of $\Xi_{\rm c}^0$ production in pp collisions at $\mathbf{\sqrt{s}}$ = 7 TeV

The ALICE collaboration Acharya, S. ; Adamova, Dagmar ; Adolfsson, Jonatan ; et al.
Phys.Lett.B 781 (2018) 8-19, 2018.
Inspire Record 1642729 DOI 10.17182/hepdata.83354

The production of the charm-strange baryon $\Xi_{\rm c}^0$ is measured for the first time at the LHC via its semileptonic decay into e$^+\Xi^-\nu_{\rm e}$ in pp collisions at $\sqrt{s}=7$ TeV with the ALICE detector. The transverse momentum ($p_{\rm T}$) differential cross section multiplied by the branching ratio is presented in the interval 1 $<$ $p_{\rm T}$ $<$ 8 GeV/$c$ at mid-rapidity, $|y|$ $<$ 0.5. The transverse momentum dependence of the $\Xi_{\rm c}^0$ baryon production relative to the D$^0$ meson production is compared to predictions of event generators with various tunes of the hadronisation mechanism, which are found to underestimate the measured cross-section ratio.

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

The ALICE collaboration
Phys.Lett.B 846 (2023) 137625, 2023.
Inspire Record 2088206 DOI 10.17182/hepdata.136180

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.

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Identified Charged Particles in Quark and Gluon Jets

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J.C 17 (2000) 207-222, 2000.
Inspire Record 524696 DOI 10.17182/hepdata.50064

A sample of 2.2 million hadronic Z decays, selected from the data recorded by the Delphi detector at LEP during 1994-1995 was used for an improved measurement of inclusive distributions of pi+, K+ and p and their antiparticles in gluon and quark jets. The production spectra of the individual identified particles were found to be softer in gluon jets compared to quark jets, with a higher multiplicity in gluon jets as observed for inclusive charged particles. A significant proton enhancement in gluon jets is observed indicating that baryon production proceeds directly from colour objects. The maxima, xi^*, of the xi-distributions for kaons in gluon and quark jets are observed to be different.

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Inclusive $\phi$ Meson Production in Electron - Positron Interactions in the Energy Region of the $\Upsilon$ Resonances

The ARGUS collaboration Albrecht, H. ; Bockmann, P. ; Glaser, R. ; et al.
Z.Phys.C 41 (1989) 557, 1989.
Inspire Record 262551 DOI 10.17182/hepdata.15528

We report on a high precision measurement of ϕ-meson production in continuum events and in direct decays of the Υ(1S)- and Υ(2S)-mesons. The ratio of the total production rate of ϕ-mesons in direct Υ(1S)- and Υ(2S)-decays over that in continuum events is 1.32±0.08±0.09 and 1.07±0.13±0.11 respectively. This is compatible with the corresponding ratio obtained for lighter mesons, but is appreciably smaller than the relative baryon production rate.

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Inclusive Baryon Production in e+ e- Annihilation

Piccolo, M. ; Peruzzi, I. ; Luke, D. ; et al.
Phys.Rev.Lett. 39 (1977) 1503, 1977.
Inspire Record 121395 DOI 10.17182/hepdata.20965

The inclusive production of antiprotons and Λ's in e+e− annihilation has been measured as a function of the c.m. energy in the range 3.7-7.6 GeV. We find that the baryon cross section has a behavior different from the total hadronic production. Our results show a rapid rise in the ratio σp¯σμμ between 4.4 and 5 GeV, consistent with what would be expected from charmed baryon production. Λ¯ production is 10-15% of p¯ production at all energies.

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