Light neutral-meson production in pp collisions at $\mathbf{\sqrt{s}}$ = 13 TeV
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arXiv
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| Format: | Preprint |
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2024
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| author | ALICE Collaboration |
| author_facet | ALICE Collaboration |
| contents | The momentum-differential invariant cross sections of ${π^{0}}$ and $η$ mesons are reported for pp collisions at $\sqrt{s}$ = 13 TeV at midrapidity ($|y|<0.8$). The measurement is performed in a broad transverse-momentum range of $0.2<p_{\rm T}<200$ GeV/$c$ and $0.4 < p_{\rm T} < 60$ GeV/$c$ for the ${π^{0}}$ and $η$, respectively, extending the $p_{\rm T}$ coverage of previous measurements. Transverse-mass-scaling violation of up to 60% at low transverse momentum has been observed, agreeing with measurements at lower collision energies. Transverse Bjorken $x$ ($x_{\rm T}$) scaling of the ${π^{0}}$ cross sections at LHC energies is fulfilled with a power-law exponent of $n = 5.01 \pm 0.05$, consistent with values obtained for charged pions at similar collision energies. The data are compared to predictions from next-to-leading order perturbative QCD calculations, where the ${π^{0}}$ spectrum is best described using the CT18 parton distribution function and the NNFF1.0 or BDSS fragmentation function. Expectations from PYTHIA8 and EPOS LHC overestimate the spectrum for the ${π^{0}}$ and are not able to describe the shape and magnitude of the $η$ spectrum. The charged-particle multiplicity dependent ${π^{0}}$ and $η$ $p_{\rm T}$ spectra show the expected change of the spectral shape, characterized by a flatter slope with increasing multiplicity. This is demonstrated across a broad transverse-momentum range and up to events with a charged-particle multiplicity exceeding five times the mean value in minimum bias collisions. The $η/π^{0}$ ratio depends on the charged-particle multiplicity for $ p_{\rm T} < 4$ GeV/$c$. PYTHIA8 and EPOS LHC qualitatively explain this behavior with an increasing contribution from the feed-down of heavier particles to the ${π^{0}}$ spectrum. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2411_09560 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Light neutral-meson production in pp collisions at $\mathbf{\sqrt{s}}$ = 13 TeV ALICE Collaboration High Energy Physics - Experiment Nuclear Experiment The momentum-differential invariant cross sections of ${π^{0}}$ and $η$ mesons are reported for pp collisions at $\sqrt{s}$ = 13 TeV at midrapidity ($|y|<0.8$). The measurement is performed in a broad transverse-momentum range of $0.2<p_{\rm T}<200$ GeV/$c$ and $0.4 < p_{\rm T} < 60$ GeV/$c$ for the ${π^{0}}$ and $η$, respectively, extending the $p_{\rm T}$ coverage of previous measurements. Transverse-mass-scaling violation of up to 60% at low transverse momentum has been observed, agreeing with measurements at lower collision energies. Transverse Bjorken $x$ ($x_{\rm T}$) scaling of the ${π^{0}}$ cross sections at LHC energies is fulfilled with a power-law exponent of $n = 5.01 \pm 0.05$, consistent with values obtained for charged pions at similar collision energies. The data are compared to predictions from next-to-leading order perturbative QCD calculations, where the ${π^{0}}$ spectrum is best described using the CT18 parton distribution function and the NNFF1.0 or BDSS fragmentation function. Expectations from PYTHIA8 and EPOS LHC overestimate the spectrum for the ${π^{0}}$ and are not able to describe the shape and magnitude of the $η$ spectrum. The charged-particle multiplicity dependent ${π^{0}}$ and $η$ $p_{\rm T}$ spectra show the expected change of the spectral shape, characterized by a flatter slope with increasing multiplicity. This is demonstrated across a broad transverse-momentum range and up to events with a charged-particle multiplicity exceeding five times the mean value in minimum bias collisions. The $η/π^{0}$ ratio depends on the charged-particle multiplicity for $ p_{\rm T} < 4$ GeV/$c$. PYTHIA8 and EPOS LHC qualitatively explain this behavior with an increasing contribution from the feed-down of heavier particles to the ${π^{0}}$ spectrum. |
| title | Light neutral-meson production in pp collisions at $\mathbf{\sqrt{s}}$ = 13 TeV |
| topic | High Energy Physics - Experiment Nuclear Experiment |
| url | https://arxiv.org/abs/2411.09560 |