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. Fig_1.pdf [229 KiB] HiDef png [838 KiB] Thumbnail [499 KiB] *.C file tex code Projections of the extended unbinned maximum likelihood fit to (left) $m_1^{\mu ^+\mu ^- }$ and (right) $m_2^{\mu ^+\mu ^- }$ for $p_{\mathrm{T}}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} } >2\mathrm{ Ge V}$. 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. Fig_2.pdf [143 KiB] HiDef png [273 KiB] Thumbnail [219 KiB] *.C file tex code 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. Fig_3.pdf [303 KiB] HiDef png [579 KiB] Thumbnail [431 KiB] *.C file tex code 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. Fig_4.pdf [302 KiB] HiDef png [580 KiB] Thumbnail [429 KiB] *.C file tex code 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. Fig_5.pdf [299 KiB] HiDef png [597 KiB] Thumbnail [438 KiB] *.C file tex code 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. Fig_6.pdf [297 KiB] HiDef png [603 KiB] Thumbnail [438 KiB] *.C file tex code Normalized differential production crossdash-sections (points with error bars) for $p_{\mathrm{T}}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} } >2 {\mathrm{ Ge V /}c}$ (left) and $p_{\mathrm{T}}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} } >3 {\mathrm{ Ge V /}c}$ (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. Fig_7.pdf [250 KiB] HiDef png [519 KiB] Thumbnail [395 KiB] *.C file tex code Normalized differential production crossdash-sections (points with error bars) for $p_{\mathrm{T}}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} } >5 {\mathrm{ Ge V /}c}$ (left) and $p_{\mathrm{T}}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} } >7 {\mathrm{ Ge V /}c}$ (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. Fig_8.pdf [251 KiB] HiDef png [575 KiB] Thumbnail [420 KiB] *.C file tex code Animated gif made out of all figures. PAPER-2017-020.gif Thumbnail

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. Table_1.pdf [42 KiB] HiDef png [47 KiB] Thumbnail [24 KiB] tex code Summary of relative systematic uncertainties for the efficiencydash-corrected signal yield. Table_2.pdf [23 KiB] HiDef png [74 KiB] Thumbnail [34 KiB] tex code

Created on 21 September 2019.