Onset of radial flow in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>p</mml:mi><mml:mo>+</mml:mo><mml:mi>p</mml:mi></mml:mrow></mml:math>collisions

It has been debated for decades whether hadrons emerging from $p+p$ collisions exhibit collective expansion. The signal of the collective motion in $p+p$ collisions is not as clear or as clean as in heavy-ion collisions because of the low multiplicity and large fluctuation in $p+p$ collisions. The Tsallis blast-wave (TBW) model is a thermodynamic approach, introduced to handle the overwhelming correlation and fluctuation in the hadronic processes. We have systematically studied the identified particle spectra in $p+p$ collisions from the BNL Relativistic Heavy Ion Collider (RHIC) to the CERN Large Hadron Collider (LHC) using TBW and have found no appreciable radial flow in $p+p$ collisions below $\sqrt{s}=900$ GeV. At the LHC higher energy of 7 TeV in $p+p$ collisions, the radial flow velocity achieves an average value of $\ensuremath{\langle}\ensuremath{\beta}\ensuremath{\rangle}=0.320\ifmmode\pm\else\textpm\fi{}0.005$. This flow velocity is comparable to that in peripheral (40--60%) $\mathrm{Au}+\mathrm{Au}$ collisions at the RHIC. Breaking of the identified particle spectra ${m}_{T}$ scaling was also observed at the LHC from a model-independent test.

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