Compact Muon Solenoid
LHC, CERN
Visit us: CMS Public Website, CMS Physics ;
Contact us: CMS Publications Committee
| CMS-HIN-22-001 ; CERN-EP-2024-138 | ||
| Search for nuclear modifications of $ {\mathrm{B}^{+}} $ meson production in pPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 8.16 TeV | ||
| CMS Collaboration | ||
| 7 July 2024 | ||
| Submitted to Phys. Rev. Lett. | ||
| Abstract: Nuclear medium effects on $ {\mathrm{B}^{+}} $ meson production are studied using the binary-collision scaled cross section ratio between events of different multiplicities from proton-lead collisions. Data, collected by the CMS experiment in 2016 at a nucleon-nucleon center-of-mass energy of $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 8.16 TeV, corresponding to an integrated luminosity of 175 nb$^{-1}$, were used. The scaling factors in the ratio are determined using a novel approach based on the $ \mathrm{Z}\to\mu^{-}\mu^{+} $ cross sections measured in the same events. The scaled ratio for $ {\mathrm{B}^{+}} $ is consistent with unity for all event multiplicities, putting stringent constraints on nuclear modification for heavy flavor. | ||
| Links: e-print arXiv:2407.05402 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ; | ||
| Figures | |
png pdf |
Figure 1:
Reconstructed $ \psi(\text{2S}) \mathrm{K^+} $ invariant mass distributions for $ {\mathrm{B}^{+}} $ meson candidates with 3 $ < p_{\mathrm{T}} < $ 50 GeV, in events with 2 $ < N_{\text{ch}} < $ 60 (left) or 110 $ < N_{\text{ch}} < $ 250 (right). The result of the fit described in the text is also shown. |
png pdf |
Figure 1-a:
Reconstructed $ \psi(\text{2S}) \mathrm{K^+} $ invariant mass distributions for $ {\mathrm{B}^{+}} $ meson candidates with 3 $ < p_{\mathrm{T}} < $ 50 GeV, in events with 2 $ < N_{\text{ch}} < $ 60 (left) or 110 $ < N_{\text{ch}} < $ 250 (right). The result of the fit described in the text is also shown. |
png pdf |
Figure 1-b:
Reconstructed $ \psi(\text{2S}) \mathrm{K^+} $ invariant mass distributions for $ {\mathrm{B}^{+}} $ meson candidates with 3 $ < p_{\mathrm{T}} < $ 50 GeV, in events with 2 $ < N_{\text{ch}} < $ 60 (left) or 110 $ < N_{\text{ch}} < $ 250 (right). The result of the fit described in the text is also shown. |
png pdf |
Figure 2:
(left) $ {\mathrm{B}^{+}} $ differential cross section in $ p_{\mathrm{T}} $ bins. Vertical bars (boxes) represent the statistical (systematic) uncertainties. The global systematic uncertainty, not included in the data points, comprises the uncertainties in the integrated luminosity measurement and the $ {\mathrm{B}^{+}} $ meson branching fraction. Results are compared to FONLL calculations, scaled by the number of binary nucleon-nucleon collisions. The yellow boxes represent the theoretical uncertainties from FONLL calculations [37,38,39]. (right) $ {\mathrm{B}^{+}} $ differential cross section shown in $ p_{\mathrm{T}} $ bins divided into classes of $ N_{\text{ch}} $. For better visibility, data points are scaled by a factor of 2 (blue), 4 (magenta), or 8 (red). Vertical bars represent total uncertainties. |
png pdf |
Figure 2-a:
(left) $ {\mathrm{B}^{+}} $ differential cross section in $ p_{\mathrm{T}} $ bins. Vertical bars (boxes) represent the statistical (systematic) uncertainties. The global systematic uncertainty, not included in the data points, comprises the uncertainties in the integrated luminosity measurement and the $ {\mathrm{B}^{+}} $ meson branching fraction. Results are compared to FONLL calculations, scaled by the number of binary nucleon-nucleon collisions. The yellow boxes represent the theoretical uncertainties from FONLL calculations [37,38,39]. (right) $ {\mathrm{B}^{+}} $ differential cross section shown in $ p_{\mathrm{T}} $ bins divided into classes of $ N_{\text{ch}} $. For better visibility, data points are scaled by a factor of 2 (blue), 4 (magenta), or 8 (red). Vertical bars represent total uncertainties. |
png pdf |
Figure 2-b:
(left) $ {\mathrm{B}^{+}} $ differential cross section in $ p_{\mathrm{T}} $ bins. Vertical bars (boxes) represent the statistical (systematic) uncertainties. The global systematic uncertainty, not included in the data points, comprises the uncertainties in the integrated luminosity measurement and the $ {\mathrm{B}^{+}} $ meson branching fraction. Results are compared to FONLL calculations, scaled by the number of binary nucleon-nucleon collisions. The yellow boxes represent the theoretical uncertainties from FONLL calculations [37,38,39]. (right) $ {\mathrm{B}^{+}} $ differential cross section shown in $ p_{\mathrm{T}} $ bins divided into classes of $ N_{\text{ch}} $. For better visibility, data points are scaled by a factor of 2 (blue), 4 (magenta), or 8 (red). Vertical bars represent total uncertainties. |
png pdf |
Figure 3:
The $ R_{\mathrm{HL}} $ for $ {\mathrm{B}^{+}} $ in $ p_{\mathrm{T}} $ bins for the highest and lowest multiplicity classes (left), and in the full $ p_{\mathrm{T}} $ range and as a function of the multiplicity density (right). The error bars correspond to the statistical uncertainty, and the boxes represent the sum in quadrature of systematic uncertainties. |
png pdf |
Figure 3-a:
The $ R_{\mathrm{HL}} $ for $ {\mathrm{B}^{+}} $ in $ p_{\mathrm{T}} $ bins for the highest and lowest multiplicity classes (left), and in the full $ p_{\mathrm{T}} $ range and as a function of the multiplicity density (right). The error bars correspond to the statistical uncertainty, and the boxes represent the sum in quadrature of systematic uncertainties. |
png pdf |
Figure 3-b:
The $ R_{\mathrm{HL}} $ for $ {\mathrm{B}^{+}} $ in $ p_{\mathrm{T}} $ bins for the highest and lowest multiplicity classes (left), and in the full $ p_{\mathrm{T}} $ range and as a function of the multiplicity density (right). The error bars correspond to the statistical uncertainty, and the boxes represent the sum in quadrature of systematic uncertainties. |
png pdf |
Figure 4:
Z boson differential cross section in $ p_{\mathrm{T}} $ bins for the different multiplicity classes. The vertical bars represent the total uncertainties. |
| Tables | |
png pdf |
Table 1:
Fraction of the full event sample that contains a $ {\mathrm{B}^{+}} $ meson candidate in each multiplicity class, and corrected multiplicity for charged particles with $ |y| < $ 2.4 and $ p_{\mathrm{T}} > $ 0.4 GeV. Systematic uncertainties are given for the corrected multiplicities, while statistical uncertainties are negligible. |
png pdf |
Table 2:
Summary of differential cross sections ($ \mu$b GeV$^{-1}$) as a function of $ p_{\mathrm{T}} $($ {\mathrm{B}^{+}} $) in pPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 8.16 TeV. The uncertainties in the integrated luminosity measurement and the $ {\mathrm{B}^{+}} $ meson branching fraction are not included in the systematic uncertainties. |
| Summary |
| In summary, the $ {\mathrm{B}^{+}} $ meson differential production cross sections have been measured as a function of the meson transverse momentum in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of 8.16 TeV. The exclusive $ {\mathrm{B}^{+}}\!\to\! \mathrm{J}/\psi \mathrm{K^+} $ decay channel was used to reconstruct the $ {\mathrm{B}^{+}} $ mesons. The fixed-order next-to-leading logarithmic predictions are in agreement with the inclusive measurement. The $ {\mathrm{B}^{+}} $ cross section has been measured for the first time in different classes of charged-particle multiplicity in pPb collisions, revealing an expected rising trend in the $ {\mathrm{B}^{+}} $ production with increasing charged-particle multiplicity. The scaled ratio of $ {\mathrm{B}^{+}} $ meson cross sections in high- to low-multiplicity events were used to study nuclear medium effects on heavy flavor production. The scaling factors, characterizing the relative number of binary collisions between event classes of different multiplicities, were obtained, for the first time, in a data-driven way from ratios of the measured Z boson cross sections in the same events. The observed ratios are consistent with unity within uncertainties for all event selections studied, setting constraints on possible presence of medium effects in the $ {\mathrm{B}^{+}} $ meson production. The novel approach relying on the Z boson measurements to extract the scaling factors provides future opportunities for medium effect searches, particularly in small collision systems. |
| References | ||||
| 1 | E. V. Shuryak | Theory of hadronic plasma | Sov. Phys. JETP 47 (1978) 212 | |
| 2 | J. C. Collins and M. J. Perry | Superdense matter: neutrons or asymptotically free quarks? | PRL 34 (1975) 1353 | |
| 3 | PHENIX Collaboration | Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration | Nucl. Phys. A 757 (2005) 184 | nucl-ex/0410003 |
| 4 | STAR Collaboration | Experimental and theoretical challenges in the search for the quark gluon plasma: The STAR Collaboration's critical assessment of the evidence from RHIC collisions | Nucl. Phys. A 757 (2005) 102 | nucl-ex/0501009 |
| 5 | W. Busza, K. Rajagopal, and W. van der Schee | Heavy ion collisions: The big picture, and the big questions | Ann. Rev. Nucl. Part. Sci. 68 (2018) 339 | 1802.04801 |
| 6 | CMS Collaboration | Overview of high-density QCD studies with the CMS experiment at the LHC | Submitted to Physics Reports, 2024 | CMS-HIN-23-011 2405.10785 |
| 7 | CMS Collaboration | Observation of long-range near-side angular correlations in proton-lead collisions at the LHC | PLB 718 (2013) 795 | CMS-HIN-12-015 1210.5482 |
| 8 | ATLAS Collaboration | Observation of associated near-side and away-side long-range correlations in $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV proton-lead collisions with the ATLAS detector | PRL 110 (2013) 182302 | 1212.5198 |
| 9 | ALICE Collaboration | Long-range angular correlations on the near and away side in pPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV | PLB 719 (2013) 29 | 1212.2001 |
| 10 | LHCb Collaboration | Measurements of long-range near-side angular correlations in $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5 TeV proton-lead collisions in the forward region | PLB 762 (2016) 473 | 1512.00439 |
| 11 | ALICE Collaboration | Long-range angular correlations of $ \pi $, $ \mathrm{K} $ and p in p--Pb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 5.02 TeV | PLB 726 (2013) 164 | 1307.3237 |
| 12 | CMS Collaboration | Long-range two-particle correlations of strange hadrons with charged particles in pPb and PbPb collisions at LHC energies | PLB 742 (2015) 200 | CMS-HIN-14-002 1409.3392 |
| 13 | CMS Collaboration | Evidence for collective multi-particle correlations in pPb collisions | PRL 115 (2015) 012301 | CMS-HIN-14-006 1502.05382 |
| 14 | ALICE Collaboration | Multiplicity dependence of pion, kaon, proton and lambda production in p-Pb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV | PLB 728 (2014) 25 | 1307.6796 |
| 15 | ATLAS Collaboration | Correlated long-range mixed-harmonic fluctuations measured in pp, p+Pb and low-multiplicity PbPb collisions with the ATLAS detector | PLB 789 (2019) 444 | 1807.02012 |
| 16 | CMS Collaboration | Observation of prompt $ \mathrm{J}/\psi $ meson elliptic flow in high-multiplicity $ \mathrm{p} $Pb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 8.16 TeV | PLB 791 (2019) 172 | CMS-HIN-18-010 1810.01473 |
| 17 | CMS Collaboration | Measurement of prompt and nonprompt $ \mathrm{J}/\psi $ production in pp and $ \mathrm{p}\mathrm{Pb} $ collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 5.02 TeV | EPJC 77 (2017) 269 | CMS-HIN-14-009 1702.01462 |
| 18 | CMS Collaboration | Elliptic anisotropy measurement of the f$ _0 $(980) hadron in proton-lead collisions and evidence for its quark-antiquark composition | Submitted to Nature Physics, 2023 | CMS-HIN-20-002 2312.17092 |
| 19 | CMS Collaboration | Observation of long-range near-side angular correlations in proton-proton collisions at the LHC | JHEP 09 (2010) 091 | CMS-QCD-10-002 1009.4122 |
| 20 | ATLAS Collaboration | Observation of long-range elliptic azimuthal anisotropies in $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 13 and 2.76 TeV pp collisions with the ATLAS detector | PRL 116 (2016) 172301 | 1509.04776 |
| 21 | CMS Collaboration | Measurement of long-range near-side two-particle angular correlations in pp collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 13 TeV | PRL 116 (2016) 172302 | CMS-FSQ-15-002 1510.03068 |
| 22 | CMS Collaboration | Evidence for collectivity in pp collisions at the LHC | PLB 765 (2017) 193 | CMS-HIN-16-010 1606.06198 |
| 23 | CMS Collaboration | Observation of correlated azimuthal anisotropy Fourier harmonics in pp and $ \mathrm{p}+ $Pb collisions at the LHC | PRL 120 (2018) 092301 | CMS-HIN-16-022 1709.09189 |
| 24 | ALICE Collaboration | Multiplicity dependence of light-flavor hadron production in pp collisions at $ \sqrt{s} = $ 7 TeV | Phys. Rev. C 99 (2019) 024906 | 1807.11321 |
| 25 | ALICE Collaboration | Azimuthal correlations of prompt $ \mathrm{D} $ mesons with charged particles in pp and p-Pb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV | EPJC 80 (2020) 979 | 1910.14403 |
| 26 | CMS Collaboration | Observation of enhanced long-range elliptic anisotropies inside high-multiplicity jets in pp collisions at $ \sqrt{s} = $ 13 TeV | Submitted to Phys. Rev. Lett, 2023 | CMS-HIN-21-013 2312.17103 |
| 27 | K. Dusling, W. Li, and B. Schenke | Novel collective phenomena in high-energy proton-proton and proton-nucleus collisions | Int. J. Mod. Phys. E 25 (2016) 1630002 | 1509.07939 |
| 28 | J. L. Nagle and W. A. Zajc | Small system collectivity in relativistic hadronic and nuclear collisions | Ann. Rev. Nucl. Part. Sci. 68 (2018) 211 | 1801.03477 |
| 29 | CMS Collaboration | Studies of charm and beauty hadron long-range correlations in pp and pPb collisions at LHC energies | PLB 813 (2021) 136036 | CMS-HIN-19-009 2009.07065 |
| 30 | X. Dong, Y.-J. Lee, and R. Rapp | Open heavy-flavor production in heavy-ion collisions | Ann. Rev. Nucl. Part. Sci. 69 (2019) 417 | 1903.07709 |
| 31 | L. Apolin \'a rio, Y.-J. Lee, and M. Winn | Heavy quarks and jets as probes of the QGP | Prog. Part. Nucl. Phys. 127 (2022) 103990 | 2203.16352 |
| 32 | CMS Collaboration | Study of azimuthal anisotropy of $ \Upsilon(1S) $ mesons in pPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 8.16 TeV | PLB 850 (2024) 138518 | CMS-HIN-21-001 2310.03233 |
| 33 | LHCb Collaboration | Measurement of $ {\mathrm{B}^{+}} $, $ \mathrm{B}_{d} $ and $ \Lambda_{b} $ production in $ \mathrm{p}\mathrm{Pb} $ collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 8.16 TeV | PRD 99 (2019) 052011 | 1902.05599 |
| 34 | STAR Collaboration | Particle type dependence of azimuthal anisotropy and nuclear modification of particle production in Au + Au collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 200 GeV | PRL 92 (2004) 052302 | nucl-ex/0306007 |
| 35 | PHOBOS Collaboration | Centrality dependence of charged hadron transverse momentum spectra in Au + Au collisions from $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 62.4 GeV to 200 GeV | PRL 94 (2005) 082304 | nucl-ex/0405003 |
| 36 | STAR Collaboration | STAR heavy-ion highlights | EPJ Web Conf. 126 (2016) 02027 | |
| 37 | M. Cacciari et al. | Theoretical predictions for charm and bottom production at the LHC | JHEP 10 (2012) 137 | 1205.6344 |
| 38 | M. Cacciari, S. Frixione, and P. Nason | The $ p_{\mathrm{T}} $ spectrum in heavy-flavour photoproduction | JHEP 03 (2001) 006 | hep-ph/0102134 |
| 39 | M. Cacciari, M. Greco, and P. Nason | The $ p_{\mathrm{T}} $ spectrum in heavy-flavour hadroproduction | JHEP 05 (1998) 007 | hep-ph/9803400 |
| 40 | CMS Collaboration | HEPData record for this analysis | link | |
| 41 | CMS Collaboration | The CMS experiment at the CERN LHC | JINST 3 (2008) S08004 | |
| 42 | CMS Collaboration | Performance of the CMS Level-1 trigger in proton-proton collisions at $ \sqrt{s} = $ 13 TeV | JINST 15 (2020) P10017 | CMS-TRG-17-001 2006.10165 |
| 43 | CMS Collaboration | The CMS trigger system | JINST 12 (2017) P01020 | CMS-TRG-12-001 1609.02366 |
| 44 | CMS Collaboration | Electron and photon reconstruction and identification with the CMS experiment at the CERN LHC | JINST 16 (2021) P05014 | CMS-EGM-17-001 2012.06888 |
| 45 | CMS Collaboration | Performance of the CMS muon detector and muon reconstruction with proton-proton collisions at $ \sqrt{s} = $ 13 TeV | JINST 13 (2018) P06015 | CMS-MUO-16-001 1804.04528 |
| 46 | CMS Collaboration | Description and performance of track and primary-vertex reconstruction with the CMS tracker | JINST 9 (2014) P10009 | CMS-TRK-11-001 1405.6569 |
| 47 | CMS Collaboration | Particle-flow reconstruction and global event description with the CMS detector | JINST 12 (2017) P10003 | CMS-PRF-14-001 1706.04965 |
| 48 | CMS Collaboration | Performance of reconstruction and identification of $ \tau $ leptons decaying to hadrons and $ \nu_{\!\tau} $ in pp collisions at $ \sqrt{s}= $ 13 TeV | JINST 13 (2018) P10005 | CMS-TAU-16-003 1809.02816 |
| 49 | CMS Collaboration | Jet energy scale and resolution in the CMS experiment in pp collisions at 8 TeV | JINST 12 (2017) P02014 | CMS-JME-13-004 1607.03663 |
| 50 | CMS Collaboration | Performance of missing transverse momentum reconstruction in proton-proton collisions at $ \sqrt{s} = $ 13 TeV using the CMS detector | JINST 14 (2019) P07004 | CMS-JME-17-001 1903.06078 |
| 51 | CMS Collaboration | Charged-particle nuclear modification factors in PbPb and $ \mathrm{p}\mathrm{Pb} $ collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV | JHEP 04 (2017) 039 | CMS-HIN-15-015 1611.01664 |
| 52 | Particle Data Group Collaboration | Review of particle physics | PTEP 2022 (2022) 083C01 | |
| 53 | T. Sjöstrand et al. | An introduction to PYTHIA 8.2 | Comput. Phys. Commun. 191 (2015) 159 | 1410.3012 |
| 54 | D. Lange | The EVTGEN particle decay simulation package | NIM A 462 (2001) 152 | |
| 55 | N. Davidson, T. Przedzinski, and Z. Was | PHOTOS interface in C++: technical and physics documentation | Comput. Phys. Commun. 199 (2016) 86 | 1011.0937 |
| 56 | GEANT4 Collaboration | GEANT 4---a simulation toolkit | NIM A 506 (2003) 250 | |
| 57 | T. Pierog et al. | EPOS LHC: Test of collective hadronization with data measured at the CERN Large Hadron Collider | Phys. Rev. C 92 (2015) 034906 | 1306.0121 |
| 58 | CMS Collaboration | Tracking POG results for pion efficiency with the $ \mathrm{D}^{*} $ meson using data from 2016 and 2017 | CMS Detector Performance Report CMS-DP-2018-050, 2018 CDS |
|
| 59 | CMS Collaboration | Upsilon production cross-section in pp collisions at $ \sqrt{s}= $ 7 TeV | PRD 83 (2011) 112004 | CMS-BPH-10-003 1012.5545 |
| 60 | N. L. Johnson | Systems of frequency curves generated by methods of translation | Biometrika 36 (1949) 149 | |
| 61 | S. Jackman | Bayesian analysis for the social sciences | John Wiley \& Sons, New Jersey, USA, 2009 link |
|
| 62 | CMS Collaboration | CMS luminosity measurement using 2016 proton-nucleus collisions at nucleon-nucleon center-of-mass energy of 8.16 TeV | CMS Physics Analysis Summary, 2018 CMS-PAS-LUM-17-002 |
CMS-PAS-LUM-17-002 |
| 63 | CMS Collaboration | Study of Drell-Yan dimuon production in proton-lead collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 8.16 TeV | JHEP 05 (2021) 182 | CMS-HIN-18-003 2102.13648 |
| 64 | CMS Collaboration | Supplemental material: $ {\mathrm{B}^{+}} $ meson and Z boson differential cross sections | Link to be supplied by publisher | |
|
|
Compact Muon Solenoid LHC, CERN |
|
|
|
|
|
|