Measurement of differential $$ b\overline{b} $$- and $$ c\overline{c} $$-dijet cross-sections in the forward region of pp collisions at $$ \sqrt{s} $$ = 13 TeV

Abstract

The inclusive $$ b\overline{b} $$ b b ¯ - and $$ c\overline{c} $$ c c ¯ -dijet production cross-sections in the forward region of pp collisions are measured using a data sample collected with the LHCb detector at a centre-of-mass energy of 13 TeV in 2016. The data sample corresponds to an integrated luminosity of 1.6 fb−1. Differential cross-sections are measured as a function of the transverse momentum and of the pseudorapidity of the leading jet, of the rapidity difference between the jets, and of the dijet invariant mass. A fiducial region for the measurement is defined by requiring that the two jets originating from the two b or c quarks are emitted with transverse momentum greater than 20 GeV/c, pseudorapidity in the range 2.2 < η < 4.2, and with a difference in the azimuthal angle between the two jets greater than 1.5. The integrated $$ b\overline{b} $$ b b ¯ -dijet cross-section is measured to be 53.0 ± 9.7 nb, and the total $$ c\overline{c} $$ c c ¯ -dijet cross-section is measured to be 73 ± 16 nb. The ratio between $$ c\overline{c} $$ c c ¯ - and $$ b\overline{b} $$ b b ¯ -dijet cross-sections is also measured and found to be 1.37 ± 0.27. The results are in agreement with theoretical predictions at next-to-leading order.

Searches for rare $$ {B}_s^0 $$ and B0 decays into four muons

“…Note that the reconstruction weights are only used in the calculation of the efficiencies of the BDT requirements, since requirements on the B candidate's vertex χ 2 per degree of freedom and the impact parameter χ 2 imposed in prior stages of the selection are highly efficient for the signal modes. The individual efficiencies for each year are then combined in a weighted average according to the integrated luminosity recorded and the bb production cross-section in that year [35,36].…”

The role of multi-parton interactions in doubly-heavy hadron production

“…Jet flavour-tagging algorithms use similar displaced vertex tagging algorithms as already discussed to determine if a jet is the result of a heavy flavour quark. Recent measurements of heavy dijets at LHCb claim a reconstruction efficiency for b b and c c dijets of about 15% and 1.5%, respectively [45]. Therefore in a significant fraction of events containing quarkonia it may be feasible to additionally reconstruct these jets, assuming that the rate of fake jets can be sufficiently controlled.…”

The role of multi-parton interactions in doubly-heavy hadron production

“…Jet flavour-tagging algorithms use similar displaced vertex tagging algorithms as already discussed to determine if a jet is the result of a heavy flavour quark. Recent measurements of heavy dijets at LHCb claim a reconstruction efficiency for b b and cc dijets of about 15% and 1.5%, respectively [44]. Therefore in a significant fraction of events containing quarkonia it may be feasible to additionally reconstruct these jets, assuming that the rate of fake jets can be sufficiently controlled.…”