Measurement of the Z boson production cross-section in proton-lead collisions at $ \sqrt{s_{\textrm{NN}}} $ = 8.16 TeV

Information

LHCb-PAPER-2022-009
CERN-EP-2022-089
arXiv:2205.10213 [PDF]

(Submitted on 20 May 2022)
JHEP 06 (2023) 022
Inspire 2085913

Tools

Abstract

This article presents the first measurement of the differential $Z$-boson production cross-section in the forward region using proton-lead collisions with the LHCb detector. The dataset was collected at a nucleon-nucleon centre-of-mass energy of $\sqrt{s_\mathrm{NN}}=8.16 \mathrm{TeV}$ in 2016, corresponding to an integrated luminosity of $30.8 \mathrm{nb}^{-1}$. The forward-backward ratio and the nuclear modification factors are measured together with the differential cross-section as functions of the $Z$ boson rapidity in the centre-of-mass frame, the transverse momentum of the $Z$ boson and a geometric variable $\phi^{*}$. The results are in good agreement with the predictions from nuclear parton distribution functions, providing strong constraining power at small Bjorken-$x$.

Figures and captions

Dimuon invariant mass of the selected events for (a) forward and (b) backward collisions, respectively. The red histograms show the distributions from simulation normalised to the number of observed candidates.	Fig1a.pdf [14 KiB] HiDef png [137 KiB] Thumbnail [136 KiB] *.C file
	Fig1b.pdf [14 KiB] HiDef png [140 KiB] Thumbnail [145 KiB] *.C file
The measured overall $ Z \rightarrow \mu ^+\mu ^- $ production fiducial cross-section compared to the PowhegBox prediction using CTEQ6.1, EPPS16 and nCTEQ15 (n)PDF sets, for forward and backward collisions, respectively.	Fig2.pdf [197 KiB] HiDef png [330 KiB] Thumbnail [236 KiB] *.C file
The measured differential fiducial cross-section as a function of $ y^{*}_{ Z }$ for (a) forward and (b) backward collisions. The theoretical predictions are calculated using PowhegBox with CTEQ6.1, EPPS16 and nCTEQ15 (n)PDF sets.	Fig3a.pdf [198 KiB] HiDef png [312 KiB] Thumbnail [218 KiB] *.C file
	Fig3b.pdf [198 KiB] HiDef png [218 KiB] Thumbnail [166 KiB] *.C file
The measured differential fiducial cross-section as a function of $ p_{\mathrm{T}}^{ Z }$ for (a) forward and (b) backward collisions, and the corresponding version for (c) forward and (d) backward collisions with fine intervals at low $ p_{\mathrm{T}}^{ Z }$ . The theoretical predictions are calculated using PowhegBox with CTEQ6.1, EPPS16 and nCTEQ15 (n)PDF sets.	Fig4a.pdf [164 KiB] HiDef png [227 KiB] Thumbnail [193 KiB] *.C file
	Fig4b.pdf [165 KiB] HiDef png [207 KiB] Thumbnail [190 KiB] *.C file
	Fig4c.pdf [165 KiB] HiDef png [345 KiB] Thumbnail [238 KiB] *.C file
	Fig4d.pdf [165 KiB] HiDef png [257 KiB] Thumbnail [207 KiB] *.C file
The measured differential fiducial cross-section as a function of $\phi^{*}$ for (a) forward and (b) backward collisions. The theoretical predictions are calculated using PowhegBox with CTEQ6.1, EPPS16 and nCTEQ15 (n)PDF sets.	Fig5a.pdf [165 KiB] HiDef png [207 KiB] Thumbnail [176 KiB] *.C file
	Fig5b.pdf [165 KiB] HiDef png [198 KiB] Thumbnail [173 KiB] *.C file
The measured forward-backward ratio ( $ R_\mathrm{FB}$ ), (a) for the overall measurement, (b) as a function of $ y^{}_{ Z }$ , (c) as a function of $ p_{\mathrm{T}}^{ Z }$ , and (d) as a function of $\phi^{}$ , together with the PowhegBox predictions using CTEQ6.1, EPPS16 and nCTEQ15 (n)PDF sets.	Fig6a.pdf [197 KiB] HiDef png [285 KiB] Thumbnail [212 KiB] *.C file
	Fig6b.pdf [199 KiB] HiDef png [375 KiB] Thumbnail [249 KiB] *.C file
	Fig6c.pdf [198 KiB] HiDef png [356 KiB] Thumbnail [265 KiB] *.C file
	Fig6d.pdf [198 KiB] HiDef png [324 KiB] Thumbnail [236 KiB] *.C file
Measurements of the nuclear modification factor ( $ R_{ p \mathrm{Pb}}$ ) compared to the PowhegBox predictions using the EPPS16 and nCTEQ15 (n)PDF sets.	Fig7.pdf [196 KiB] HiDef png [300 KiB] Thumbnail [221 KiB] *.C file
Nuclear modification factors ( $ R_{ p \mathrm{Pb}}$ ) as a function of (top row) $ y^{}_{ Z }$ , (middle row) $ p_{\mathrm{T}}^{ Z }$ and (bottom row) $\phi^{}$ , together with the PowhegBox prediction using EPPS16 and nCTEQ15 nPDF sets, where the left column is for forward collisions and the right column is for backward collisions.	Fig8a.pdf [197 KiB] HiDef png [376 KiB] Thumbnail [235 KiB] *.C file
	Fig8b.pdf [197 KiB] HiDef png [269 KiB] Thumbnail [184 KiB] *.C file
	Fig8c.pdf [163 KiB] HiDef png [330 KiB] Thumbnail [222 KiB] *.C file
	Fig8d.pdf [163 KiB] HiDef png [256 KiB] Thumbnail [196 KiB] *.C file
	Fig8e.pdf [193 KiB] HiDef png [331 KiB] Thumbnail [189 KiB] *.C file
	Fig8f.pdf [163 KiB] HiDef png [261 KiB] Thumbnail [167 KiB] *.C file
Animated gif made out of all figures.	PAPER-2022-009.gif Thumbnail

Tables and captions

Observed number of candidates, input values and uncertainties for the overall cross-section and the theory corrections with uncertainties for the $ R_\mathrm{FB}$ and $ R_{ p \mathrm{Pb}}$ measurements.	Table_1.pdf [74 KiB] HiDef png [111 KiB] Thumbnail [56 KiB] tex code
The $ y^{}_{\mu}$ acceptance correction factors ( $ k_\mathrm{FB}$ ) for $ R_\mathrm{FB}$ measured in intervals of $ y^{}_{ Z }$ , $ p_{\mathrm{T}}^{ Z }$ , and $\phi^{*}$ .	Table_2.pdf [64 KiB] HiDef png [50 KiB] Thumbnail [24 KiB] tex code
The $ y^{}_{\mu}$ acceptance correction factors ( $ k_{ p \mathrm{Pb}}$ ) for $ R_{ p \mathrm{Pb}}$ measured in intervals of $ y^{}_{ Z }$ , $ p_{\mathrm{T}}^{ Z }$ , and $\phi^{*}$ for forward and backward collisions.	Table_3.pdf [67 KiB] HiDef png [103 KiB] Thumbnail [44 KiB] tex code
Correlation matrix of statistical uncertainty in $ y^{*}_{ Z }$ intervals for forward collisions.	Table_4.pdf [50 KiB] HiDef png [47 KiB] Thumbnail [25 KiB] tex code
Correlation matrix of statistical uncertainty in $ y^{*}_{ Z }$ intervals for backward collisions.	Table_5.pdf [57 KiB] HiDef png [40 KiB] Thumbnail [19 KiB] tex code
Correlation matrix of statistical uncertainty in $ p_{\mathrm{T}}^{ Z }$ intervals for forward collisions.	Table_6.pdf [51 KiB] HiDef png [56 KiB] Thumbnail [27 KiB] tex code
Correlation matrix of statistical uncertainty in $ p_{\mathrm{T}}^{ Z }$ intervals for backward collisions.	Table_7.pdf [51 KiB] HiDef png [56 KiB] Thumbnail [27 KiB] tex code
Correlation matrix of statistical uncertainty in $\phi^{*}$ intervals for forward collisions.	Table_8.pdf [43 KiB] HiDef png [55 KiB] Thumbnail [26 KiB] tex code
Correlation matrix of statistical uncertainty in $\phi^{*}$ intervals for backward collisions.	Table_9.pdf [43 KiB] HiDef png [55 KiB] Thumbnail [26 KiB] tex code
Correlation matrix of statistical uncertainty in $ p_{\mathrm{T}}^{ Z }$ intervals for forward collisions in the low $ p_{\mathrm{T}}^{ Z }$ range.	Table_10.pdf [52 KiB] HiDef png [59 KiB] Thumbnail [29 KiB] tex code
Correlation matrix of statistical uncertainty in $ p_{\mathrm{T}}^{ Z }$ intervals for backward collisions in the low $ p_{\mathrm{T}}^{ Z }$ range.	Table_11.pdf [52 KiB] HiDef png [59 KiB] Thumbnail [29 KiB] tex code
Correlation matrix of efficiency uncertainty in $ y^{*}_{ Z }$ intervals for forward collisions.	Table_12.pdf [51 KiB] HiDef png [49 KiB] Thumbnail [26 KiB] tex code
Correlation matrix of efficiency uncertainty in $ y^{*}_{ Z }$ intervals for backward collisions.	Table_13.pdf [58 KiB] HiDef png [41 KiB] Thumbnail [20 KiB] tex code
Correlation matrix of efficiency uncertainty in $ p_{\mathrm{T}}^{ Z }$ intervals for forward collisions.	Table_14.pdf [51 KiB] HiDef png [57 KiB] Thumbnail [28 KiB] tex code
Correlation matrix of efficiency uncertainty in $ p_{\mathrm{T}}^{ Z }$ intervals for backward collisions.	Table_15.pdf [51 KiB] HiDef png [56 KiB] Thumbnail [28 KiB] tex code
Correlation matrix of efficiency uncertainty in $\phi^{*}$ intervals for forward collisions.	Table_16.pdf [44 KiB] HiDef png [57 KiB] Thumbnail [27 KiB] tex code
Correlation matrix of efficiency uncertainty in $\phi^{*}$ intervals for backward collisions.	Table_17.pdf [44 KiB] HiDef png [57 KiB] Thumbnail [27 KiB] tex code
Correlation matrix of efficiency uncertainty in $ p_{\mathrm{T}}^{ Z }$ intervals for forward collisions in the low $ p_{\mathrm{T}}^{ Z }$ range.	Table_18.pdf [50 KiB] HiDef png [44 KiB] Thumbnail [16 KiB] tex code
Differential cross-section of $ Z \rightarrow \mu ^+\mu ^- $ in intervals of $ y^{*}_{ Z }$ for forward and backward collisions, together with the FSR correction. In the differential cross-section results, the first uncertainty is statistical, the second is systematic and the third is from integrated luminosity.	Table_20.pdf [68 KiB] HiDef png [91 KiB] Thumbnail [46 KiB] tex code
Differential cross-section of $ Z \rightarrow \mu ^+\mu ^- $ in intervals of $ p_{\mathrm{T}}^{ Z }$ for forward and backward collisions, together with the FSR correction. In the differential cross-section results, the first uncertainty is statistical, the second is systematic and the third is from integrated luminosity.	Table_21.pdf [69 KiB] HiDef png [140 KiB] Thumbnail [70 KiB] tex code
Differential cross-section of $ Z \rightarrow \mu ^+\mu ^- $ in intervals of $ p_{\mathrm{T}}^{ Z }$ for forward and backward collisions in the low $ p_{\mathrm{T}}^{ Z }$ region, together with the FSR correction. In the differential cross-section results, the first uncertainty is statistical, the second is systematic and the third is from integrated luminosity.	Table_22.pdf [62 KiB] HiDef png [152 KiB] Thumbnail [82 KiB] tex code
Differential cross-section of $ Z \rightarrow \mu ^+\mu ^- $ in intervals of $\phi^{*}$ for forward and backward collisions, together with the FSR correction. In the differential cross-section results, the first uncertainty is statistical, the second is systematic and the third is from integrated luminosity.	Table_23.pdf [61 KiB] HiDef png [132 KiB] Thumbnail [67 KiB] tex code
The forward-backward ratio ( $ R_\mathrm{FB}$ ) in intervals of $\| y^{*}_{ Z } \|$, together with the FSR correction. For the $ R_\mathrm{FB}$ results, the first uncertainty is statistical, the second is systematic and the third is from integrated luminosity.	Table_24.pdf [67 KiB] HiDef png [44 KiB] Thumbnail [20 KiB] tex code
The forward-backward ratio ( $ R_\mathrm{FB}$ ) in intervals of $ p_{\mathrm{T}}^{ Z }$ , together with the FSR correction. For the $ R_\mathrm{FB}$ results, the first uncertainty is statistical, the second is systematic and the third is from integrated luminosity.	Table_25.pdf [61 KiB] HiDef png [80 KiB] Thumbnail [26 KiB] tex code
The forward-backward ratio ( $ R_\mathrm{FB}$ ) in intervals of $\phi^{*}$ , together with the FSR correction. For the $ R_\mathrm{FB}$ results, the first uncertainty is statistical, the second is systematic and the third is from integrated luminosity.	Table_26.pdf [60 KiB] HiDef png [75 KiB] Thumbnail [36 KiB] tex code
The nuclear modification factors ( $ R_{ p \mathrm{Pb}}$ ) in intervals of $ y^{*}_{ Z }$ for forward and backward collisions, together with the FSR correction. For the $ R_{ p \mathrm{Pb}}$ results, the first uncertainty is statistical, the second is systematic and the third is from integrated luminosity.	Table_27.pdf [67 KiB] HiDef png [80 KiB] Thumbnail [40 KiB] tex code
The nuclear modification factors ( $ R_{ p \mathrm{Pb}}$ ) in intervals of $ p_{\mathrm{T}}^{ Z }$ for forward and backward collisions, together with the FSR correction. For the $ R_{ p \mathrm{Pb}}$ results, the first uncertainty is statistical, the second is systematic and the third is from integrated luminosity.	Table_28.pdf [61 KiB] HiDef png [138 KiB] Thumbnail [67 KiB] tex code
The nuclear modification factors ( $ R_{ p \mathrm{Pb}}$ ) in intervals of $\phi^{*}$ for forward and backward collisions, together with the FSR correction. For the $ R_{ p \mathrm{Pb}}$ results, the first uncertainty is statistical, the second is systematic and the third is from integrated luminosity.	Table_29.pdf [67 KiB] HiDef png [124 KiB] Thumbnail [69 KiB] tex code

Supplementary Material [file]

Supplementary material full pdf	supple[..].pdf [156 KiB]
This ZIP file contains supplementary materials for the publication LHCb-PAPER-2022-009. supplementary.pdf : the supplementary document supplementary.tex : the latex supplementary codes main-supplementary.tex : the main latex codes .pdf, .png, *.eps : The figures	Fig1.pdf [17 KiB] HiDef png [153 KiB] Thumbnail [134 KiB] *C file

Created on 20 April 2024.

The LHCb Public results

Measurement of the Z boson production cross-section in proton-lead collisions at $ \sqrt{s_{\textrm{NN}}} $ = 8.16 TeV

Information

LHCb-PAPER-2022-009

CERN-EP-2022-089

arXiv:2205.10213 [PDF]

(Submitted on 20 May 2022)

JHEP 06 (2023) 022

Inspire 2085913

Tools

Cited 11 times

Get BibTex

Abstract

Figures and captions

Tables and captions

Supplementary Material [file]