CMS-HIN-17-008

CMS-HIN-17-008 ; CERN-EP-2018-257
Measurement of $\mathrm{B}^{0}_{\mathrm{s}}$ meson production in pp and PbPb collisions at $\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}} =$ 5.02 TeV
CMS Collaboration
6 October 2018
Phys. Lett. B 796 (2019) 168
Abstract: The production cross sections of $\mathrm{B}^{0}_{\mathrm{s}}$ mesons and charge conjugates are measured in proton-proton (pp) and PbPb collisions via the exclusive decay channel ${\mathrm{B}^{0}_{\mathrm{s}} \to \mathrm{J}/\psi \phi \to \mu^{+}\mu^{-}\mathrm{K^{+}}\mathrm{K^{-}}}$ at a centre-of-mass energy of 5.02 TeV per nucleon pair and within the rapidity range $\| y \| <$ 2.4 using the CMS detector at the LHC. The pp measurement is performed as a function of transverse momentum ( ${p_{\mathrm{T}}}$ ) of the $\mathrm{B}^{0}_{\mathrm{s}}$ meson in the range of 7 to 50 GeV/ $c$ and is compared to the predictions of perturbative QCD calculations. The $\mathrm{B}^{0}_{\mathrm{s}}$ production yield in PbPb collisions is measured in two ${p_{\mathrm{T}}}$ intervals, 7 to 15 and 15 to 50 GeV/ $c$ , and compared to the yield in pp collisions in the same kinematic region. The nuclear modification factor ( ${R_{\mathrm{AA}}}$ ) is found to be 1.5 $\pm$ 0.6 (stat) $\pm$ 0.5 (syst) for 7-15 GeV/ $c$ , and 0.87 $\pm$ 0.30 (stat) $\pm$ 0.17 (syst) for 15-50 GeV/ $c$ , respectively. Within current uncertainties, the results are consistent with models of strangeness enhancement and a suppression as observed for the $\mathrm{B^{+}}$ mesons.
Links: e-print arXiv:1810.03022 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: Invariant mass distributions of ${\mathrm {B}^0_\mathrm {s}}$ candidates in pp (left) and PbPb (right) collisions measured in the range $\| y \| <$ 2.4 and in the ${p_{\mathrm {T}}}$ range of 7-15 GeV/ $c$ . The $\chi ^2$ divided by the number of degrees of freedom (nDOF) is also given.
png pdf	Figure 1-a: Invariant mass distributions of ${\mathrm {B}^0_\mathrm {s}}$ candidates in pp collisions measured in the range $\| y \| <$ 2.4 and in the ${p_{\mathrm {T}}}$ range of 7-15 GeV/ $c$ . The $\chi ^2$ divided by the number of degrees of freedom (nDOF) is also given.
png pdf	Figure 1-b: Invariant mass distributions of ${\mathrm {B}^0_\mathrm {s}}$ candidates in PbPb collisions measured in the range $\| y \| <$ 2.4 and in the ${p_{\mathrm {T}}}$ range of 7-15 GeV/ $c$ . The $\chi ^2$ divided by the number of degrees of freedom (nDOF) is also given.
png pdf	Figure 2: Invariant mass distributions of ${\mathrm {B}^0_\mathrm {s}}$ candidates in pp (left) and PbPb (right) collisions measured in the range $\| y \| <$ 2.4 and in the ${p_{\mathrm {T}}}$ range of 15-50 GeV/ $c$ . The $\chi ^2$ divided by the number of degrees of freedom (nDOF) is also given.
png pdf	Figure 2-a: Invariant mass distributions of ${\mathrm {B}^0_\mathrm {s}}$ candidates in pp collisions measured in the range $\| y \| <$ 2.4 and in the ${p_{\mathrm {T}}}$ range of 15-50 GeV/ $c$ . The $\chi ^2$ divided by the number of degrees of freedom (nDOF) is also given.
png pdf	Figure 2-b: Invariant mass distributions of ${\mathrm {B}^0_\mathrm {s}}$ candidates in PbPb collisions measured in the range $\| y \| <$ 2.4 and in the ${p_{\mathrm {T}}}$ range of 15-50 GeV/ $c$ . The $\chi ^2$ divided by the number of degrees of freedom (nDOF) is also given.
png pdf	Figure 3: The ${p_{\mathrm {T}}}$ -differential production cross section of ${\mathrm {B}^0_\mathrm {s}}$ in pp collisions at ${\sqrt {s}} =$ 5.02 TeV in three ${p_{\mathrm {T}}}$ intervals from 7 to 50 GeV/ $c$ . The vertical bars (boxes) correspond to statistical (systematic) uncertainties. The systematic uncertainty boxes here include both the correlated and uncorrelated contributions added in quadrature. The global systematic uncertainty, listed in the legend and not included in the point-to-point uncertainties, comprises the uncertainties in the integrated luminosity measurement and in the branching fraction $\mathcal {B}$ . The pp cross section is compared to FONLL calculations [28] represented by the colored yellow boxes with the heights indicating the theoretical uncertainty.
png pdf	Figure 4: (left) The ${p_{\mathrm {T}}}$ -differential production cross section of ${\mathrm {B}^0_\mathrm {s}}$ mesons in pp collisions and the ${p_{\mathrm {T}}}$ -differential corrected yield of ${\mathrm {B}^0_\mathrm {s}}$ mesons scaled by ${T_{\mathrm {AA}}}$ in PbPb collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 5.02 TeV in two ${p_{\mathrm {T}}}$ intervals from 7 to 50 GeV/ $c$ . The vertical bars (boxes) correspond to statistical (systematic) uncertainties. The systematic uncertainty boxes here include both the correlated and uncorrelated contributions added in quadrature. The global systematic uncertainty comprises the uncertainties in ${T_{\mathrm {AA}}}$ , $N_{\text {MB}}$ , and $\mathcal {B}$ . (right) The nuclear modification factor ${R_{\mathrm {AA}}}$ of ${\mathrm {B}^0_\mathrm {s}}$ measured in PbPb collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 5.02 TeV from 7 to 50 GeV/ $c$ . The vertical bars (boxes) correspond to statistical (systematic) uncertainties. The ${{\mathrm {B}^{+}}}$ ${R_{\mathrm {AA}}}$ measurement [29] is also shown for comparison. The global systematic uncertainty, represented by colored boxes at ${R_{\mathrm {AA}}} =$ 1, comprises the uncertainties in the integrated luminosity measurement and ${T_{\mathrm {AA}}}$ value. Two theoretical calculations are also shown for comparison: TAMU [49,19] and CUJET3.0 [46,47,48]. The line width of the theoretical calculation from Refs. [49,19] represents the size of its statistical uncertainty.
png pdf	Figure 4-a: The ${p_{\mathrm {T}}}$ -differential production cross section of ${\mathrm {B}^0_\mathrm {s}}$ mesons in pp collisions and the ${p_{\mathrm {T}}}$ -differential corrected yield of ${\mathrm {B}^0_\mathrm {s}}$ mesons scaled by ${T_{\mathrm {AA}}}$ in PbPb collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 5.02 TeV in two ${p_{\mathrm {T}}}$ intervals from 7 to 50 GeV/ $c$ . The vertical bars (boxes) correspond to statistical (systematic) uncertainties. The systematic uncertainty boxes here include both the correlated and uncorrelated contributions added in quadrature. The global systematic uncertainty comprises the uncertainties in ${T_{\mathrm {AA}}}$ , $N_{\text {MB}}$ , and $\mathcal {B}$ .
png pdf	Figure 4-b: The nuclear modification factor ${R_{\mathrm {AA}}}$ of ${\mathrm {B}^0_\mathrm {s}}$ measured in PbPb collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 5.02 TeV from 7 to 50 GeV/ $c$ . The vertical bars (boxes) correspond to statistical (systematic) uncertainties. The ${{\mathrm {B}^{+}}}$ ${R_{\mathrm {AA}}}$ measurement [29] is also shown for comparison. The global systematic uncertainty, represented by colored boxes at ${R_{\mathrm {AA}}} =$ 1, comprises the uncertainties in the integrated luminosity measurement and ${T_{\mathrm {AA}}}$ value. Two theoretical calculations are also shown for comparison: TAMU [49,19] and CUJET3.0 [46,47,48]. The line width of the theoretical calculation from Refs. [49,19] represents the size of its statistical uncertainty.
png pdf	Figure 5: Nuclear modification factor $\mathrm {{R_{\mathrm {AA}}}}$ ratio between ${\mathrm {B}^0_\mathrm {s}}$ and ${{\mathrm {B}^{+}}}$ measured in PbPb collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 5.02 TeV from 7 to 50 GeV/ $c$ . Two theoretical calculations are also shown for comparison: TAMU [49,19], and CUJET3.0 [46,47,48].

Tables
png pdf	Table 1: Summary of systematic uncertainties in percentage (%) from each factor in pp and PbPb analyses.

Summary

The first measurement of the differential production cross section of

$\mathrm{B}^{0}_{\mathrm{s}}$ mesons (including both charge conjugates) in both pp and PbPb collisions at a centre-of-mass energy of 5.02 TeV per nucleon pair is presented. The

$\mathrm{B}^{0}_{\mathrm{s}}$ and

${\mathrm{\overline{B}}^0}s$ mesons are studied with the CMS detector at the LHC in the rapidity range

$| y | <$ 2.4 via the reconstruction of one of their exclusive hadronic decay channels,

${\mathrm{B}^{0}_{\mathrm{s}} \to \mathrm{J}/\psi \phi \to \mu^{+}\mu^{-}\mathrm{K^{+}}\mathrm{K^{-}}}$ . The nuclear modification factor

${R_{\mathrm{AA}}}$ of

$\mathrm{B}^{0}_{\mathrm{s}}$ is measured in the transverse momentum range from 7 to 50 GeV/

$c$ , inclusively for 0-100% event centrality. An indication of an enhancement of the

$\mathrm{B}^{0}_{\mathrm{s}}$ /

$\mathrm{B^{+}}$ ratio in PbPb with respect to pp collisions is seen. More precise measurements of the

$\mathrm{B}^{0}_{\mathrm{s}}$ and

$\mathrm{B^{\pm}}$ mesons

${R_{\mathrm{AA}}}$ with the upcoming high-luminosity LHC heavy ion runs could provide further constraints on the relevance of recombination, a marker of deconfined matter, for beauty hadron production, and unambiguous information about the mechanisms of beauty hadronisation in heavy ion collisions.

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	F. Karsch and E. Laermann	Thermodynamics and in-medium hadron properties from lattice QCD	in Quark-Gluon Plasma III, R. Hwa (ed.), 2003	hep-lat/0305025
4	J. D. Bjorken	Energy loss of energetic partons in quark-gluon plasma: possible extinction of high ${p_{\mathrm{T}}}$ jets in hadron-hadron collisions	Fermilab PUB 82-059-THY
5	R. Baier, D. Schiff, and B. G. Zakharov	Energy loss in perturbative QCD	Ann. Rev. Nucl. Part. Sci. 50 (2000) 37	hep-ph/0002198
6	CMS Collaboration	Observation and studies of jet quenching in PbPb collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 2.76 TeV	PRC 84 (2011) 024906	CMS-HIN-10-004 1102.1957
7	ATLAS Collaboration	Observation of a centrality-dependent dijet asymmetry in lead-lead collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 2.76 TeV with the ATLAS detector at the LHC	PRL 105 (2010) 252303	1011.6182
8	A. Andronic et al.	Heavy-flavour and quarkonium production in the LHC era: from proton-proton to heavy-ion collisions	EPJC 76 (2016) 107	1506.03981
9	J. Rafelski and B. Muller	Strangeness Production in the Quark - Gluon Plasma	PRL 48 (1982) 1066, .[Erratum: \DOI10.1103/PhysRevLett.56.2334]
10	STAR Collaboration	Strangeness enhancement in Cu+Cu and Au+Au collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 200 GeV	PRL 108 (2012) 072301	1107.2955
11	STAR Collaboration	Strange and multi-strange particle production in Au+Au collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 62.4 GeV	PRC 83 (2011) 024901	1010.0142
12	STAR Collaboration	Energy and system size dependence of phi meson production in Cu+Cu and Au+Au collisions	PLB 673 (2009) 183	0810.4979
13	STAR Collaboration	Enhanced strange baryon production in Au+Au collisions compared to p+p at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 200 GeV	PRC 77 (2008) 044908
14	STAR Collaboration	Scaling properties of hyperon production in Au+Au collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 200 GeV	PRL 98 (2007) 062301	nucl-ex/0606014
15	STAR Collaboration	Multistrange baryon production in Au-Au collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 130 GeV	PRL 92 (2004) 182301	nucl-ex/0307024
16	STAR Collaboration	Kaon production and kaon to pion ratio in Au+Au collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 130 GeV	PLB 595 (2004) 143	nucl-ex/0206008
17	STAR Collaboration	${\mathrm{K^{\ast}(892)}}^0$ production in relativistic heavy ion collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 130 GeV	PRC 66 (2002) 061901	nucl-ex/0205015
18	ALICE Collaboration	Multi-strange baryon production at mid-rapidity in Pb-Pb collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 2.76 TeV	PLB 728 (2014) 216	1307.5543
19	M. He, R. J. Fries, and R. Rapp	Heavy flavor at the large hadron collider in a strong coupling approach	PLB 735 (2014) 445	1401.3817
20	D. Molnar and S. A. Voloshin	Elliptic flow at large transverse momenta from quark coalescence	PRL 91 (2003) 092301	nucl-th/0302014
21	V. Greco, C. M. Ko, and P. Levai	Parton coalescence at RHIC	PRC 68 (2003) 034904	nucl-th/0305024
22	V. Greco, C. M. Ko, and R. Rapp	Quark coalescence for charmed mesons in ultrarelativistic heavy ion collisions	PLB 595 (2004) 202	nucl-th/0312100
23	ALICE Collaboration	Measurement of D $_{s}^{+}$ production and nuclear modification factor in Pb-Pb collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 2.76 TeV	JHEP 03 (2016) 082	1509.07287
24	CMS Collaboration	Measurement of the $\mathrm{B}^{0}s$ production cross section with $\mathrm{B}^{0}s \rightarrow \mathrm{J}/\psi \phi$ decays in pp collisions at $\$ \sqrt{s} =$ 7 TeV	PRD 84 (2011) 052008	CMS-BPH-10-013 1106.4048
25	CMS Collaboration	Study of $B$ meson production in p+Pb collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 5.02 TeV using exclusive hadronic decays	PRL 116 (2016) 032301	CMS-HIN-14-004 1508.06678
26	M. Cacciari, M. Greco, and P. Nason	The ${p_{\mathrm{T}}}$ spectrum in heavy-flavour hadroproduction	JHEP 05 (1998) 007	hep-ph/9803400
27	M. Cacciari and P. Nason	Charm cross sections for the Tevatron Run II	JHEP 09 (2003) 006	hep-ph/0306212
28	M. Cacciari et al.	Theoretical predictions for charm and bottom production at the LHC	JHEP 10 (2012) 137	1205.6344
29	CMS Collaboration	Measurement of the ${B}^{\pm}$ meson nuclear modification factor in Pb-Pb collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 5.02 TeV	PRL 119 (2017) 152301	CMS-HIN-16-011 1705.04727
30	Particle Data Group Collaboration	Review of particle physics	CPC 40 (2016) 100001
31	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
32	CMS Collaboration	Performance of CMS muon reconstruction in pp collision events at $\sqrt{s}=$ 7 TeV	JINST 7 (2012) P10002	CMS-MUO-10-004 1206.4071
33	CMS Collaboration	The CMS experiment at the CERN LHC	JINST 3 (2008) S08004	CMS-00-001
34	T. Sjostrand et al.	An introduction to PYTHIA 8.2	CPC 191 (2015) 159	1410.3012
35	CMS Collaboration	Event generator tunes obtained from underlying event and multiparton scattering measurements	EPJC 76 (2016)	CMS-GEN-14-001 1512.00815
36	J. Allison et al.	Recent developments in Geant4	NIMA 835 (2016) 186
37	D. J. Lange	The EvtGen particle decay simulation package	NIMA 462 (2001) 152
38	E. Barberio, B. van Eijk, and Z. Was	PHOTOS: A universal monte carlo for QED radiative corrections in decays	CPC 66 (1991) 115
39	I. P. Lokhtin and A. M. Snigirev	A model of jet quenching in ultrarelativistic heavy ion collisions and high- ${p_{\mathrm{T}}}$ hadron spectra at RHIC	EPJC 45 (2006) 211	hep-ph/0506189
40	CMS Collaboration	Charged-particle nuclear modification factors in PbPb and pPb collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} =$ 5.02 TeV	JHEP 04 (2017) 039	CMS-HIN-15-015 1611.01664
41	CMS Collaboration	Transverse momentum and pseudorapidity distributions of charged hadrons in pp collisions at $\$ \sqrt{s} =$ $ 0.9 and 2.76 TeV	JHEP 02 (2010) 041	CMS-QCD-09-010 1002.0621
42	CMS Collaboration	CMS luminosity calibration for the pp reference run at $\sqrt{s} =$ 5.02 TeV	CMS-PAS-LUM-16-001	CMS-PAS-LUM-16-001
43	H. Voss, A. Hocker, J. Stelzer, and F. Tegenfeldt	TMVA -- the toolkit for multivariate data analysis	in XIth International Workshop on Advanced Computing and Analysis Techniques in Physics Research (ACAT), p. 40 2009	physics/0703039
44	M. L. Miller, K. Reygers, S. J. Sanders, and P. Steinberg	Glauber modeling in high-energy nuclear collisions	Ann. Rev. Nucl. Part. Sci. 57 (2007) 205	nucl-ex/0701025
45	CMS Collaboration	Measurements of inclusive W and Z cross sections in pp collisions at $\$ \sqrt{s} =$ $ 7 TeV	JHEP 01 (2011) 080	CMS-EWK-10-002 1012.2466
46	J. Xu, J. Liao, and M. Gyulassy	Bridging soft-hard transport properties of quark-gluon plasmas with CUJET3.0	JHEP 02 (2016) 169	1508.00552
47	J. Xu, J. Liao, and M. Gyulassy	Consistency of perfect fluidity and jet quenching in semi-quark-gluon monopole plasmas	Chin. PL32 (2015) 092501	1411.3673
48	J. Xu, A. Buzzatti, and M. Gyulassy	Azimuthal jet flavor tomography with CUJET2.0 of nuclear collisions at RHIC and LHC	JHEP 08 (2014) 063	1402.2956
49	M. He, R. J. Fries, and R. Rapp	Heavy-quark diffusion and hadronization in quark-gluon plasma	PRC 86 (2012) 014903	1106.6006