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Study of $b\bar{b}$ correlations in high energy proton-proton collisions

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Abstract

Kinematic correlations for pairs of beauty hadrons, produced in high energy proton-proton collisions, are studied. The data sample used was collected with the LHCb experiment at centre-of-mass energies of 7 and 8 TeV and corresponds to an integrated luminosity of 3 fb$^{-1}$. The measurement is performed using inclusive $b\rightarrow J/\psi X$ decays in the rapidity range $2<y^{J/\psi}<4.5$. The observed correlations are in good agreement with theoretical predictions.

Figures and captions

Distribution of $m_1^{\mu ^+\mu ^- }$ vs $m_2^{\mu ^+\mu ^- }$ for selected pairs of $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \rightarrow \mu ^+\mu ^- $ candidates in different $ p_{\mathrm{T}}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} } $ regions.

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Projections of the extended unbinned maximum likelihood fit to (left) $m_1^{\mu ^+\mu ^- }$ and (right) $m_2^{\mu ^+\mu ^- }$ for $ p_{\mathrm{T}}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} } >2\mathrm{\,GeV} $. The total fit function is shown as a solid thick orange line. The solid thin red curve shows the signal component, while the background with one true $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ candidate is shown by the dashed magenta line and the pure combinatorial background is shown with a dotted thin blue line.

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Normalized differential production crossdash-sections (points with error bars) for a) $\left|\Delta\phi ^{\ast}\right|/\pi$, b) $\left|\Delta\eta ^{\ast}\right|$, c) $\mathcal{A}_{\mathrm{T}}$, d) $m^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }$, e) $p^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }_{\mathrm{T}}$ and f) $y^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }$ together with the {\sc{Powheg}} (orange line) and Pythia (green band) predictions. The expectations for uncorrelated $ b \overline b $ production are shown by the dashed magenta line. The uncertainties in the {\sc{Powheg}} and $ Pythia $ predictions due to the choice of factorization and renormalization scales are shown as orange crossdash-hatched and green solid areas, respectively.

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Normalized differential production crossdash-sections (points with error bars) for a) $\left|\Delta\phi ^{\ast}\right|/\pi$, b) $\left|\Delta\eta ^{\ast}\right|$, c) $\mathcal{A}_{\mathrm{T}}$, d) $m^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }$, e) $p^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }_{\mathrm{T}}$ and f) $y^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }$ together with the {\sc{Powheg}} (orange line) and Pythia (green band) predictions. The expectations for uncorrelated $ b \overline b $ production are shown by the dashed magenta line. The uncertainties in the {\sc{Powheg}} and $ Pythia $ predictions due to the choice of factorization and renormalization scales are shown as crossdash-hatched and green solid areas, respectively.

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Normalized differential production crossdash-sections (points with error bars) for a) $\left|\Delta\phi ^{\ast}\right|/\pi$, b) $\left|\Delta\eta ^{\ast}\right|$, c) $\mathcal{A}_{\mathrm{T}}$, d) $m^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }$, e) $p^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }_{\mathrm{T}}$ and f) $y^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }$ together with the {\sc{Powheg}} (orange line) and Pythia (green band) predictions. The expectations for uncorrelated $ b \overline b $ production are shown by the dashed magenta line. The uncertainties in the {\sc{Powheg}} and $ Pythia $ predictions due to the choice of factorization and renormalization scales are shown as orange crossdash-hatched and green solid areas, respectively.

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Normalized differential production crossdash-sections (points with error bars) for a) $\left|\Delta\phi ^{\ast}\right|/\pi$, b) $\left|\Delta\eta ^{\ast}\right|$, c) $\mathcal{A}_{\mathrm{T}}$, d) $m^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }$, e) $p^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }_{\mathrm{T}}$ and f) $y^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }$ together with the {\sc{Powheg}} (orange line) and Pythia (green band) predictions. The expectations for uncorrelated $ b \overline b $ production are shown by the dashed magenta line. The uncertainties in the {\sc{Powheg}} and $ Pythia $ predictions due to the choice of factorization and renormalization scales are shown as orange crossdash-hatched and green solid areas, respectively.

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Normalized differential production crossdash-sections (points with error bars) for $ p_{\mathrm{T}}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} } >2 {\mathrm{\,GeV\!/}c} $\,(left) and $ p_{\mathrm{T}}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} } >3 {\mathrm{\,GeV\!/}c} $\,(right) data for a,b)\,$\left|\Delta\phi ^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }\right|/\pi$, c,d)\,$\left|\Delta\eta ^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }\right|$, and e,f)\,$\left|\Delta y^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }\right|$, together with the {\sc{Powheg}}\,(orange line) and Pythia \,(green band) predictions. The expectations for uncorrelated $ b \overline b $ production are shown by the dashed magenta line. The uncertainties in the {\sc{Powheg}} and $ Pythia $ predictions due to the choice of factorization and renormalization scales are shown as orange crossdash-hatched and and green solid areas, respectively.

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Normalized differential production crossdash-sections (points with error bars) for $ p_{\mathrm{T}}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} } >5 {\mathrm{\,GeV\!/}c} $\,(left) and $ p_{\mathrm{T}}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} } >7 {\mathrm{\,GeV\!/}c} $\,(right) data for a,b)\,$\left|\Delta\phi ^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }\right|/\pi$, c,d)\,$\left|\Delta\eta ^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }\right|$, and e,f)\,$\left|\Delta y^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }\right|$, together with the {\sc{Powheg}}\,(orange line) and Pythia \,(green band) predictions. The expectations for uncorrelated $ b \overline b $ production are shown by the dashed magenta line. The uncertainties in the {\sc{Powheg}} and Pythia predictions due to the choice of factorization and renormalization scales are shown as orange crossdash-hatched and and green solid areas, respectively.

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Animated gif made out of all figures.

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Tables and captions

Signal and background yields from the extended unbinned maximum likelihood fit for different requirements on $ p_{\mathrm{T}}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} }$ . The uncertainties are statistical only.

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Summary of relative systematic uncertainties for the efficiencydash-corrected signal yield.

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Created on 09 December 2018.Citation count from INSPIRE on 09 December 2018.