Abstract (data abstract)

This article reports about the properties of the underlying event measured with ALICE at the LHC in pp and p-Pb collisions at $\sqrt{s_{\rm NN}}= 5.02$ TeV. The event activity, quantified by charged-particle number and summed-$p_{\rm T}$ densities, is measured as a function of the leading-particle transverse momentum ($p_{\rm T}^{\rm trig}$). These quantities are studied in three azimuthal-angle regions relative to the leading particle in the event: toward, away, and transverse. Results are presented for three different $p_{\rm T}$ thresholds (0.15, 0.5 and 1 GeV/$c$) at mid-pseudorapidity ($|\\eta|<0.8$). The event activity in the transverse region, which is the most sensitive to the underlying event, exhibits similar behaviour in both pp and p-Pb collisions, namely, a steep increase with $p_{\rm T}^{\rm trig}$ for low $p_{\rm T}^{\rm trig}$, followed by a saturation at $p_{\rm T}^{\rm trig} \approx 5$ GeV/$c$. The results from pp collisions are compared with existing measurements at other centre-of-mass energies. The quantities in the toward and away regions are also analyzed after the subtraction of the contribution measured in the transverse region. The remaining jet-like particle densities are consistent in pp and p-Pb collisions for $p_{\rm T}^{\rm trig}>10$ GeV/$c$, whereas for lower $p_{\rm T}^{\rm trig}$ values the event activity is slightly higher in pPb than in pp collisions. The measurements are compared with predictions from the Monte Carlo event generators.

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Figure 4

10.17182/hepdata.133032.v1/t1

Fig. 4: Number density $N_{\rm ch}$ (left) and $\Sigma p_{\rm T}$ (right) distributions as a function of $p_{\rm T}^{\rm trig}$...
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Figure 5

10.17182/hepdata.133032.v1/t2

Fig. 5: Number density $N_{\rm ch}$ (left) and $\Sigma p_{\rm T}$ (right) distributions as a function of $p_{\rm T}^{\rm trig}$...
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Figure 6

10.17182/hepdata.133032.v1/t3

Fig. 6a: Number density $N_{\rm ch}$ (left) and $\Sigma p_{\rm T}$ (right) distributions as a function of $p_{\rm T}^{\rm trig}$...
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Figure 6

10.17182/hepdata.133032.v1/t4

Fig. 6b: Number density $N_{\rm ch}$ (left) and $\Sigma p_{\rm T}$ (right) distributions as a function of $p_{\rm T}^{\rm trig}$...
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Figure 7

10.17182/hepdata.133032.v1/t5

Fig. 7a: $$ as a function of $p_{\rm T}^{\rm trig}$ in Toward (left) and Away (right) regions after the...
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Figure 7

10.17182/hepdata.133032.v1/t6

Fig. 7b: $$ as a function of $p_{\rm T}^{\rm trig}$ in Toward (left) and Away (right) regions after the...
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Figure A1

10.17182/hepdata.133032.v1/t7

Fig. A1: Number density $N_{\rm ch}$ (left) and $\Sigma p_{\rm T}$ (right) distributions as a function of $p_{\rm T}^{\rm trig}$...
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Figure A2

10.17182/hepdata.133032.v1/t8

Fig. A2: Number density $N_{\rm ch}$ (left) and $\Sigma p_{\rm T}$ (right) distributions as a function of $p_{\rm T}^{\rm trig}$...
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Figure A3

10.17182/hepdata.133032.v1/t9

Fig. A3: Number density $N_{\rm ch}$ (left) and $\Sigma p_{\rm T}$ (right) distributions as a function of $p_{\rm T}^{\rm trig}$...
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Figure A4

10.17182/hepdata.133032.v1/t10

Fig. A4: Number density $N_{\rm ch}$ (left) and $\Sigma p_{\rm T}$ (right) distributions as a function of $p_{\rm T}^{\rm trig}$...

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