The dependence of $\mathrm{f}_{0}$(980) production on the final-state charged-particle multiplicity in p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV is reported. The production of $\mathrm{f}_{0}$(980) is measured with the ALICE detector via the $\mathrm{f}_0 (980) \rightarrow \pi^{+}\pi^{-}$ decay channel in a midrapidity region of $-0.5<~y<~0$. Particle yield ratios of $\mathrm{f}_{0}$(980) to $\pi$ and $\mathrm{K}^{*}$(892)$^{0}$ are found to be decreasing with increasing charged-particle multiplicity. The magnitude of the suppression of the $\mathrm{f}_{0}$(980)/$\pi$ and $\mathrm{f}_{0}$(980)/$\mathrm{K}^{*}$(892)$^{0}$ yield ratios is found to be dependent on the transverse momentum $p_{\mathrm{T}}$, suggesting different mechanisms responsible for the measured effects. Furthermore, the nuclear modification factor $Q_{\mathrm{pPb}}$ of $\mathrm{f}_{0}$(980) is measured in various multiplicity ranges. The $Q_{\mathrm{pPb}}$ shows a strong suppression of the $\mathrm{f}_{0}$(980) production in the $p_{\mathrm{T}}$ region up to about 4 GeV/$c$. The results on the particle yield ratios and $Q_{\mathrm{pPb}}$ for $\mathrm{f}_{0}$(980) may help to understand the late hadronic phase in p$-$Pb collisions and the nature of the internal structure of $\mathrm{f}_{0}$(980) particle.
Phys. Lett. B 853 (2024) 138665
HEP Data
e-Print: arXiv:2311.11786 | PDF | inSPIRE
CERN-EP-2023-263
Figure group
Figure 1
Invariant mass distribution of $\pi^{+}\pi^{-}$ pairs in $-0.5< y< 0$ after the like-sign background subtraction in p$-$Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV. The left (right) plot is obtained at low (high) $\pt$ of $\pi^+\pi^-$ pairs in minimum bias events. The abbreviation of Res. bkg represents the residual background |   |
Figure 2
Transverse momentum spectra of ${\rm f_0(980)}$ in p$-$Pb collisions at $\snn$ = 5.02 TeV for different multiplicity classes, which are scaled for visibility. Statistical and systematic uncertainties are shown as error bars and boxes, respectively. The normalization uncertainty of 13% due to the uncertainty of the $\mathrm{B.R.}$ is not shown in the figure. The lower panel shows the ratios of the spectra in multiplicity classes to the NSD spectrum. |  |
Figure 3
Double ratios of $\phi$, ${\rm K^*(892)^0}$, and ${\rm f_0(980)}$ to $\pi$ (left) and $f_0(980)$ to ${\rm K^*(892)^0}$ (right) as a function of charged-particle multiplicity raised to the power of 1/3. The ratio in each multiplicity class is divided by the ratio in low-multiplicity (LM, 60--100%) events to allow for a direct comparison among different hadron species and reduce systematic uncertainties. V0A is utilized to categorize events based on their multiplicity. Predictions from the canonical statistical model are represented with lines. |   |
Figure 4
The particle yield ratios of ${\rm f_0(980)}$ to $\pi$ as a function of $p_{\rm{T}}$ in high-multiplicity (circles) and low-multiplicity (squares) p$-$Pb collisions at $\snn$ = 5.02 TeV. The lower panel shows the double ratio of ${\rm f_0(980)}$/$\pi$ between the high-multiplicity and low-multiplicity events. V0A is utilized to categorize events based on their multiplicity. |  |
Figure 5
The particle yield ratio of ${\rm f_0(980)}$ to ${\rm K^*(892)^0}$ as a function of $p_{\rm{T}}$ in high-multiplicity (circles) and low-multiplicity (squares) p$-$Pb collisions at $\snn$ = 5.02 TeV. The lower panel shows the double ratio of high-multiplicity to low-multiplicity ${\rm f_0(980)}$/${\rm K^*(892)^0}$. V0A is utilized to categorize events based on their multiplicity. |  |
Figure 6
Nuclear modification factor ($Q_{\rm{pPb}}$) of ${\rm f_0(980)}$ as a function of $p_{\rm{T}}$ in p$-$Pb collisions at $\snn$ = 5.02 TeV for different multiplicity classes. The multiplicity class is defined with the ZNA, which is the ZN placed on the Pb-going side. Statistical and systematic uncertainties are shown as error bars and boxes, respectively. Black boxes around unity represent the binary collision scaling uncertainties. The $Q_{\rm{pPb}}$ of charged hadrons are reported for comparison. |  |