Measurement of Bose-Einstein Correlations in pp Collisions at sqrt(s)=0.9 and 7 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M. ; Tumasyan, Armen ; et al.
JHEP 05 (2011) 029, 2011.
Inspire Record 884808 DOI 10.17182/hepdata.60018

Bose-Einstein correlations between identical particles are measured in samples of proton-proton collisions at 0.9 and 7 TeV centre-of-mass energies, recorded by the CMS experiment at the LHC. The signal is observed in the form of an enhancement of number of pairs of same-sign charged particles with small relative momentum. The dependence of this enhancement on kinematic and topological features of the event is studied.

7 data tables

The double ratio R_double at 900 and 7000 GeV.

The double ratio R_double at 7000 GeV in different bins of charged particle multiplicity and kT.

The double ratio R_double at 7000 GeV in different bins of charged particle multiplicity and kT.

More…

Transverse momentum spectra of b jets in pPb collisions at sqrt(s[NN]) = 5.02 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Lett.B 754 (2016) 59, 2016.
Inspire Record 1397180 DOI 10.17182/hepdata.72511

We present a measurement of b jet transverse momentum (pt) spectra in proton-lead (pPb) collisions using a dataset corresponding to about 35 inverse nanobarns collected with the CMS detector at the LHC. Jets from b quark fragmentation are found by exploiting the long lifetime of hadrons containing a b quark through tagging methods using distributions of the secondary vertex mass and displacement. Extracted cross sections for b jets are scaled by the effective number of nucleon-nucleon collisions and are compared to a reference obtained from PYTHIA simulations of pp collisions. The PYTHIA-based estimate of the nuclear modification factor is found to be 1.22 +/- 0.15 (stat + syst pPb) +/- 0.27 (syst PYTHIA) averaged over all jets with pt between 55 and 400 GeV/c and with abs(eta[lab]) < 2. We also compare this result to predictions from models using perturbative calculations in quantum chromodynamics.

17 data tables

Distributions of the JP tagger discriminator before applying the SSV tagger selection.

Distributions of the JP tagger discriminator after applying the SSV tagger selection.

Distributions of the b-tagging efficiency as a function of the mistag rate of light jets for pp collisions in a PYTHIA simulation.

More…

Measurement of long-range near-side two-particle angular correlations in pp collisions at sqrt(s) = 13 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Rev.Lett. 116 (2016) 172302, 2016.
Inspire Record 1397173 DOI 10.17182/hepdata.73192

Results on two-particle angular correlations for charged particles produced in pp collisions at a center-of-mass energy of 13 TeV are presented. The data were taken with the CMS detector at the LHC and correspond to an integrated luminosity of about 270 inverse nanobarns. The correlations are studied over a broad range of pseudorapidity (abs(eta) < 2.4) and over the full azimuth (phi) as a function of charged particle multiplicity and transverse momentum (pt). In high-multiplicity events, a long-range (abs(Delta eta) > 2.0), near-side (Delta phi approximately 0) structure emerges in the two-particle Delta eta-Delta phi correlation functions. The magnitude of the correlation exhibits a pronounced maximum in the range 1.0 < pt < 2.0 GeV/c and an approximately linear increase with the charged particle multiplicity, with an overall correlation strength similar to that found in earlier pp data at sqrt(s) = 7 TeV. The present measurement extends the study of near-side long-range correlations up to charged particle multiplicities of N[ch] approximately 180, a region so far unexplored in pp collisions. The observed long-range correlations are compared to those seen in pp, pPb, and PbPb collisions at lower collision energies.

38 data tables

Correlated yield obtained with the ZYAM procedure as a function of $|\Delta\Phi|$, averaged over 2 $<|\Delta\eta|<$ 4 in for 0.1 $<p_{T}<$ 1.0 $GeV/c$ and $N_{offline}^{trk}<$ 35 bins for pp data at $\sqrt =$ 13 $TeV$. The $p_{T}$ selection applies to both particles in the pair. Only statistical uncertainties are given. The subtracted ZYAM constant is given ($C_{ZYAM}$).

Correlated yield obtained with the ZYAM procedure as a function of $|\Delta\Phi|$, averaged over 2 $<|\Delta\eta|<$ 4 in for 0.1 $<p_{T}<$ 1.0 $GeV/c$ and $N_{offline}^{trk}<$ 35 bins for pp data at $\sqrt =$ 7 $TeV$. The $p_{T}$ selection applies to both particles in the pair. Only statistical uncertainties are given. The subtracted ZYAM constant is given ($C_{ZYAM}$).

Correlated yield obtained with the ZYAM procedure as a function of $|\Delta\Phi|$, averaged over 2 $<|\Delta\eta|<$ 4 in for 1.0 $<p_{T}<$ 2.0 $GeV/c$ and $N_{offline}^{trk}<$ 35 bins for pp data at $\sqrt =$ 13 $TeV$. The $p_{T}$ selection applies to both particles in the pair. Only statistical uncertainties are given. The subtracted ZYAM constant is given ($C_{ZYAM}$).

More…

Study of B meson production in pPb collisions at sqrt(s_NN) = 5.02 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Rev.Lett. 116 (2016) 032301, 2016.
Inspire Record 1390110 DOI 10.17182/hepdata.71407

The production cross sections of the B+, B0, and B0s mesons, and of their charge conjugates, are measured via exclusive hadronic decays in pPb collisions at the center-of-mass energy sqrt(s_NN) = 5.02 TeV with the CMS detector at the CERN LHC. The data set used for this analysis corresponds to an integrated luminosity of 34.6 inverse nanobarns. The production cross sections are measured in the transverse momentum range between 10 and 60 GeV/c. No significant modification is observed compared to proton-proton perturbative QCD calculations scaled by the number of incoherent nucleon-nucleon collisions. These results provide a baseline for the study of in-medium b quark energy loss in PbPb collisions.

8 data tables

The measured $p_{\rm{T}}$-differential production cross section of $B^{+}$ in $p$ + Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV, together with the cross section calculated by the FONLL model.

The measured $p_{\rm{T}}$-differential production cross section of $B^{0}$ in $p$ + Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV, together with the cross section calculated by the FONLL model.

The measured $p_{\rm{T}}$-differential production cross section of $B_{s}^{0}$ in $p$ + Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV, together with the cross section calculated by the FONLL model.

More…

Long-range two-particle correlations of strange hadrons with charged particles in pPb and PbPb collisions at LHC energies

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Lett.B 742 (2015) 200-224, 2015.
Inspire Record 1315947 DOI 10.17182/hepdata.66784

Measurements of two-particle angular correlations between an identified strange hadron (K0S or Lambda/anti-Lambda) and a charged particle, emitted in pPb collisions, are presented over a wide range in pseudorapidity and full azimuth. The data, corresponding to an integrated luminosity of approximately 35 inverse nanobarns, were collected at a nucleon-nucleon center-of-mass energy (sqrt(s[NN])) of 5.02 TeV with the CMS detector at the LHC. The results are compared to semi-peripheral PbPb collision data at sqrt(s[NN]) = 2.76 TeV, covering similar charged-particle multiplicities in the events. The observed azimuthal correlations at large relative pseudorapidity are used to extract the second-order (v[2]) and third-order (v[3]) anisotropy harmonics of K0S and Lambda/anti-Lambda particles. These quantities are studied as a function of the charged-particle multiplicity in the event and the transverse momentum of the particles. For high-multiplicity pPb events, a clear particle species dependence of v[2] and v[3] is observed. For pt < 2 GeV, the v[2] and v[3] values of K0S particles are larger than those of Lambda/anti-Lambda particles at the same pt. This splitting effect between two particle species is found to be stronger in pPb than in PbPb collisions in the same multiplicity range. When divided by the number of constituent quarks and compared at the same transverse kinetic energy per quark, both v[2] and v[3] for K0S particles are observed to be consistent with those for Lambda/anti-Lambda particles at the 10% level in pPb collisions. This consistency extends over a wide range of particle transverse kinetic energy and event multiplicities.

68 data tables

The elliptic flow v2(2, $|\Delta\eta| > 2$) extracted for all charged particles as a function of $p_{T}$ from the correlation in the $N_{offline}^{trk}$ < 35 multiplicity class in pPb.

The elliptic flow v2(2, $|\Delta\eta| > 2$) extracted for all charged particles as a function of $p_{T}$ from the correlation in the 35 $\leq N_{offline}^{trk}$ < 60 multiplicity class in pPb.

The elliptic flow v2(2, $|\Delta\eta| > 2$) extracted for all charged particles as a function of $p_{T}$ from the correlation in the 60 $\leq N_{offline}^{trk}$ < 120 multiplicity class in pPb.

More…

Study of W boson production in pPb collisions at sqrt(s[NN]) = 5.02 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Lett.B 750 (2015) 565-586, 2015.
Inspire Record 1353541 DOI 10.17182/hepdata.69232

The first study of W boson production in pPb collisions is presented, for bosons decaying to a muon or electron, and a neutrino. The measurements are based on a data sample corresponding to an integrated luminosity of 34.6 inverse nanobarns at a nucleon-nucleon centre-of-mass energy of sqrt(s[NN]) = 5.02 TeV, collected by the CMS experiment. The W boson differential cross sections, lepton charge asymmetry, and forward-backward asymmetries are measured for leptons of transverse momentum exceeding 25 GeV, and as a function of the lepton pseudorapidity in the abs(eta[lab]) < 2.4 range. Deviations from the expectations based on currently available parton distribution functions are observed, showing the need for including W boson data in nuclear parton distribution global fits.

6 data tables

Lepton charge asymmetry, $(N_{\ell}^+ - N_{\ell}^-)/(N_{\ell}^+ + N_{\ell}^-)$ as a function of the lepton pseudorapidity.

Production cross section for $\textrm{pPb} \to W^+ + X \to \ell \nu + X$ for positively (top) and negatively (bottom) charged leptons of $p_T$ larger than 25 GeV$/c$, in nanobarns, as a function of the lepton pseudorapidity. Values are given first for muons and electrons separately, then combined. The global normalization uncertainty of 3.5\% is not included in the listed uncertainties.

Production cross section for $\textrm{pPb} \to W^- + X \to \ell \nu + X$ for positively (top) and negatively (bottom) charged leptons of $p_T$ larger than 25 GeV$/c$, in nanobarns, as a function of the lepton pseudorapidity. Values are given first for muons and electrons separately, then combined. The global normalization uncertainty of 3.5\% is not included in the listed uncertainties.

More…

Observation of charge-dependent azimuthal correlations in pPb collisions and its implication for the search for the chiral magnetic effect

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Rev.Lett. 118 (2017) 122301, 2017.
Inspire Record 1489183 DOI 10.17182/hepdata.77013

Charge-dependent azimuthal particle correlations with respect to the second-order event plane in pPb and PbPb collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV have been studied with the CMS experiment at the LHC. The measurement is performed with a three-particle correlation technique, using two particles with the same or opposite charge within the pseudorapidity range abs(eta) < 2.4, and a third particle measured in the hadron forward calorimeters (4.4 < abs(eta) < 5). The observed differences between the same and opposite sign correlations, as functions of multiplicity and eta gap between the two charged particles, are of similar magnitude in pPb and PbPb collisions at the same multiplicities. These results pose a challenge for the interpretation of charge-dependent azimuthal correlations in heavy ion collisions in terms of the chiral magnetic effect.

10 data tables

Three-particle correlation with respect to the 2nd order event plane from Pb-going side in pPb collisions at multiplicity [185,220), with individual track pT between 0.3 to 3.0 GeV/c. Data points are plotted at the bin center.

Three-particle correlation with respect to the 2nd order event plane from p-going side in pPb collisions at multiplicity [185,220), with individual track pT between 0.3 to 3.0 GeV/c. Data points are plotted at the bin center.

Three-particle correlation with respect to the 2nd order event plane in PbPb collisions at multiplicity [185,220), with individual track pT between 0.3 to 3.0 GeV/c. Data points are plotted at the bin center.

More…

Measurement of prompt D0 meson azimuthal anisotropy in PbPb collisions at sqrt(s[NN]) = 5.02 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.Lett. 120 (2018) 202301, 2018.
Inspire Record 1615780 DOI 10.17182/hepdata.78930

The prompt D$^0$ meson azimuthal anisotropy coefficients, $v_2$ and $v_3$, are measured at midrapidity ($|y| < 1.0$) in PbPb collisions at a center-of-mass energy $\sqrt{s_\mathrm{NN}} = $5.02 TeV per nucleon pair with data collected by the CMS experiment. The measurement is performed in the transverse momentum ($p_\mathrm{T}$) range of 1 to 40 GeV/c, for central and midcentral collisions. The $v_2$ coefficient is found to be positive throughout the $p_\mathrm{T}$ range studied. The first measurement of the prompt D$^0$ meson $v_3$ coefficient is performed, and values up to 0.07 are observed for $p_\mathrm{T}$ around 4 GeV/c. Compared to measurements of charged particles, a similar $p_\mathrm{T}$ dependence, but smaller magnitude for $p_\mathrm{T} < $6 GeV/c, is found for prompt D$^0$ meson $v_2$ and $v_3$ coefficients. The results are consistent with the presence of collective motion of charm quarks at low $p_\mathrm{T}$ and a path length dependence of charm quark energy loss at high $p_\mathrm{T}$, thereby providing new constraints on the theoretical description of the interactions between charm quarks and the quark-gluon plasma.

6 data tables

Prompt D0 meson v2 in 0-10 centrality percentile in midrapidity (|y| < 1.0) in PbPb collisions at 5.02 TeV. The second sys is the systematic uncertainty from the nonprompt D0. The first sys is the systematic uncertainty from other sources.

Prompt D0 meson v2 in 10-30 centrality percentile in midrapidity (|y| < 1.0) in PbPb collisions at 5.02 TeV. The second sys is the systematic uncertainty from the nonprompt D0. The first sys is the systematic uncertainty from other sources.

Prompt D0 meson v2 in 30-50 centrality percentile in midrapidity (|y| < 1.0) in PbPb collisions at 5.02 TeV. The second sys is the systematic uncertainty from the nonprompt D0. The first sys is the systematic uncertainty from other sources.

More…

Pseudorapidity distributions of charged hadrons in proton-lead collisions at $\sqrt{s_{_\mathrm{NN}}} =$ 5.02 and 8.16 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 01 (2018) 045, 2018.
Inspire Record 1632453 DOI 10.17182/hepdata.80150

The pseudorapidity distributions of charged hadrons in proton-lead collisions at nucleon-nucleon center-of-mass energies $\sqrt{s_{_\mathrm{NN}}} =$ 5.02 and 8.16 TeV are presented. The measurements are based on data samples collected by the CMS experiment at the LHC. The number of primary charged hadrons produced in non-single-diffractive proton-lead collisions is determined in the pseudorapidity range $|\eta_\mathrm{lab}| <$ 2.4. The charged-hadron multiplicity distributions are compared to the predictions from theoretical calculations and Monte Carlo event generators. In the center-of-mass pseudorapidity range $|\eta_\mathrm{cm}| < 0.5$, the average charged-hadron multiplicity densities $<\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta_{\mathrm{cm}}>$$\vert_{|\eta_{\mathrm{cm}}| < 0.5}$ are 17.31 $\pm$ 0.01 (stat) $\pm$ 0.59 (syst) and 20.10 $\pm$ 0.01 (stat) $\pm$ 0.85 (syst) at $\sqrt{s_{_\mathrm{NN}}} =$ 5.02 and 8.16 TeV, respectively. The particle densities per participant nucleon are compared to similar measurements in proton-proton, proton-nucleus, and nucleus-nucleus collisions.

1 data table

Distributions of the pseudorapidity density of charged hadrons in the region $|\eta_{\mathrm{lab}}|<2.4$ in non-single-diffractive pPb collisions at $\sqrt{s_{_{\mathrm{NN}}}} = 5.02$ (open squares) and 8.16 TeV (full squares). The systematic uncertainties are correlated between the two beam energies. The proton beam goes in the positive $|\eta_{\mathrm{lab}}|$ direction.


Measurements of the charm jet cross section and nuclear modification factor in pPb collisions at sqrt(s[NN]) = 5.02 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Lett.B 772 (2017) 306-329, 2017.
Inspire Record 1507091 DOI 10.17182/hepdata.77602

The CMS Collaboration presents the first measurement of the differential cross section of jets from charm quarks produced in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of sqrt(s[NN]) = 5.02 TeV, as well as results from charm quark jets in proton-proton (pp) collisions at sqrt(s) = 2.76 and 5.02 TeV. By comparing the yields of the pPb and pp collision systems at the same energy, a nuclear modification factor for charm jets from 55 to 400 GeV/c in pPb collisions at sqrt(s[NN]) = 5.02 TeV of R[pA] = 0.92 +/- 0.07 (stat) +/- 0.11 (syst) is obtained. This is consistent with an absence of final-state energy loss for charm quarks in pPb collisions. In addition, the fraction of jets coming from charm quarks is found to be consistent with that predicted by PYTHIA 6 for pp collisions at sqrt(s)= 2.76 and 5.02 TeV, and is independent of the jet transverse momentum from 55 to 400 GeV/c.

3 data tables

Inclusive charm-jet cross section (and fraction) in pp collisions at 5.02 TeV.

Inclusive charm-jet cross section (and fraction) in pp collisions at 2.76 TeV

Inclusive charm-jet cross section in pp and pPb collisions at 5.02 TeV, with nuclear modification factor RpA for c-jets