Measurement of inclusive charged-particle b-jet production in pp and p-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ = 5.02 TeV

Abstract

A bstract A measurement of the inclusive b-jet production cross section is presented in pp and p-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:msub> <mml:mi>s</mml:mi> <mml:mi>NN</mml:mi> </mml:msub> </mml:msqrt> </mml:math> = 5 . 02 TeV, using data collected with the ALICE detector at the LHC. The jets were reconstructed in the central rapidity region |η| &lt; 0 . 5 from charged particles using the anti- k T algorithm with resolution parameter R = 0 . 4. Identification of b jets exploits the long lifetime of b hadrons, using the properties of secondary vertices and impact parameter distributions. The p T -differential inclusive production cross section of b jets, as well as the corresponding inclusive b-jet fraction, are reported for pp and p-Pb collisions in the jet transverse momentum range 10 ≤ p T , ch jet ≤ 100 GeV/ c , together with the nuclear modification factor, $$ {R}_{\mathrm{pPb}}^{\mathrm{b}-\mathrm{jet}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>R</mml:mi> <mml:mi>pPb</mml:mi> <mml:mrow> <mml:mi>b</mml:mi> <mml:mo>−</mml:mo> <mml:mi>jet</mml:mi> </mml:mrow> </mml:msubsup> </mml:math> . The analysis thus extends the lower p T limit of b-jet measurements at the LHC. The nuclear modification factor is found to be consistent with unity, indicating that the production of b jets in p-Pb at $$ \sqrt{s_{\mathrm{NN}}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:msub> <mml:mi>s</mml:mi> <mml:mi>NN</mml:mi> </mml:msub> </mml:msqrt> </mml:math> = 5 . 02 TeV is not affected by cold nuclear matter effects within the current precision. The measurements are well reproduced by POWHEG NLO pQCD calculations with PYTHIA fragmentation.