Measurement of beauty and charm production in pp collisions at $$ \sqrt{s} $$ = 5.02 TeV via non-prompt and prompt D mesons

Abstract

A bstract The p T -differential production cross sections of prompt and non-prompt (produced in beauty-hadron decays) D mesons were measured by the ALICE experiment at midrapidity ( | y | &lt; 0 . 5) in proton-proton collisions at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 5 . 02 TeV. The data sample used in the analysis corresponds to an integrated luminosity of (19 . 3 ± 0 . 4) nb − 1 . D mesons were reconstructed from their decays D 0 → K − π + , D + → K − π + π + , and $$ {\mathrm{D}}_{\mathrm{s}}^{+}\to \upphi {\uppi}^{+}\to {\mathrm{K}}^{-}{\mathrm{K}}^{+}{\uppi}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> <mml:mo>→</mml:mo> <mml:mi>ϕ</mml:mi> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>−</mml:mo> </mml:msup> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> </mml:math> and their charge conjugates. Compared to previous measurements in the same rapidity region, the cross sections of prompt D + and $$ {\mathrm{D}}_{\mathrm{s}}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> mesons have an extended p T coverage and total uncertainties reduced by a factor ranging from 1.05 to 1.6, depending on p T , allowing for a more precise determination of their p T -integrated cross sections. The results are well described by perturbative QCD calculations. The fragmentation fraction of heavy quarks to strange mesons divided by the one to non-strange mesons, f s / ( f u + f d ), is compatible for charm and beauty quarks and with previous measurements at different centre-of-mass energies and collision systems. The $$ \mathrm{b}\overline{\mathrm{b}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>b</mml:mi> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> production cross section per rapidity unit at midrapidity, estimated from non-prompt D-meson measurements, is $$ \mathrm{d}{\sigma}_{\mathrm{b}\overline{\mathrm{b}}}/\mathrm{d}y\left|{}_{\left|\mathrm{y}\right|&lt;0.5}=34.5\pm 2.4{\left(\mathrm{stat}\right)}_{-2.9}^{+4.7}\left(\mathrm{tot}.\mathrm{syst}\right)\right. $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>d</mml:mi> <mml:msub> <mml:mi>σ</mml:mi> <mml:mrow> <mml:mi>b</mml:mi> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:mrow> </mml:msub> <mml:mo>/</mml:mo> <mml:mi>d</mml:mi> <mml:mi>y</mml:mi> <mml:mfenced> <mml:mrow> <mml:msub> <mml:mrow/> <mml:mrow> <mml:mfenced> <mml:mi>y</mml:mi> </mml:mfenced> <mml:mo>&lt;</mml:mo> <mml:mn>0.5</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>34.5</mml:mn> <mml:mo>±</mml:mo> <mml:mn>2.4</mml:mn> <mml:msubsup> <mml:mfenced> <mml:mtext>stat</mml:mtext> </mml:mfenced> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2.9</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>4.7</mml:mn> </mml:mrow> </mml:msubsup> <mml:mfenced> <mml:mrow> <mml:mi>tot</mml:mi> <mml:mo>.</mml:mo> <mml:mtext>syst</mml:mtext> </mml:mrow> </mml:mfenced> </mml:mrow> </mml:mfenced> </mml:math> μb. It is compatible with previous measurements at the same centre-of-mass energy and with the cross section pre- dicted by perturbative QCD calculations.