Evidence for collectivity in pp collisions at the LHC

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Lett.B 765 (2017) 193-220, 2017.
Inspire Record 1471287 DOI 10.17182/hepdata.76506

Measurements of two- and multi-particle angular correlations in pp collisions at sqrt(s) = 5, 7, and 13 TeV are presented as a function of charged-particle multiplicity. The data, corresponding to integrated luminosities of 1.0 inverse picobarn (5 TeV), 6.2 inverse picobarns (7 TeV), and 0.7 inverse picobarns (13 TeV), were collected using the CMS detector at the LHC. The second-order (v[2]) and third-order (v[3]) azimuthal anisotropy harmonics of unidentified charged particles, as well as v[2] of K0 short and Lambda/anti-Lambda particles, are extracted from long-range two-particle correlations as functions of particle multiplicity and transverse momentum. For high-multiplicity pp events, a mass ordering is observed for the v[2] values of charged hadrons (mostly pions), K0 short, and Lambda/anti-Lambda, with lighter particle species exhibiting a stronger azimuthal anisotropy signal below pt of about 2 GeV/c. For 13 TeV data, the v[2] signals are also extracted from four- and six-particle correlations for the first time in pp collisions, with comparable magnitude to those from two-particle correlations. These observations are similar to those seen in pPb and PbPb collisions, and support the interpretation of a collective origin for the observed long-range correlations in high-multiplicity pp collisions.

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Production of psi(2S) Mesons in ppbar Collisions at 1.96 TeV

The CDF collaboration Aaltonen, T. ; Adelman, Jahred A. ; Akimoto, T. ; et al.
Phys.Rev.D 80 (2009) 031103, 2009.
Inspire Record 820328 DOI 10.17182/hepdata.57249

We have measured the differential cross section for the inclusive production of psi(2S) mesons decaying to mu^{+} mu^{-1} that were produced in prompt or B-decay processes from ppbar collisions at 1.96 TeV. These measurements have been made using a data set from an integrated luminosity of 1.1 fb^{-1} collected by the CDF II detector at Fermilab. For events with transverse momentum p_{T} (psi(2S)) > 2 GeV/c and rapidity |y(psi(2S))| < 0.6 we measure the integrated inclusive cross section sigma(ppbar -> psi(2S)X) Br(psi(2S) -> mu^{+} mu^{-}) to be 3.29 +- 0.04(stat.) +- 0.32(syst.) nb.

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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.

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Measurement of prompt and nonprompt charmonium suppression in PbPb collisions at 5.02 TeV

The CMS collaboration Sirunyan, Albert M. ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Eur.Phys.J.C 78 (2018) 509, 2018.
Inspire Record 1644903 DOI 10.17182/hepdata.80816

The nuclear modification factors of J/$\psi$ and $\psi$(2S) mesons are measured in PbPb collisions at a centre-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}} =$ 5.02 TeV. The analysis is based on PbPb and pp data samples collected by CMS at the LHC in 2015, corresponding to integrated luminosities of 464 $\mu$b$^{-1}$ and 28 pb$^{-1}$, respectively. The measurements are performed in the dimuon rapidity range of $|y| <$ 2.4 as a function of centrality, rapidity, and transverse momentum (p$_\mathrm{T}$) from p$_\mathrm{T}=$ 3 GeV/$c$ in the most forward region and up to 50 GeV/$c$. Both prompt and nonprompt (coming from b hadron decays) mesons are observed to be increasingly suppressed with centrality, with a magnitude similar to the one observed at $\sqrt{s_{\mathrm{NN}}}=$ 2.76 TeV for the two J/$\psi$ meson components. No dependence on rapidity is observed for either prompt or nonprompt J/$\psi$ mesons. An indication of a lower prompt J/$\psi$ meson suppression at p$_\mathrm{T} >$ 25 GeV/$c$ is seen with respect to that observed at intermediate p$_\mathrm{T}$. The prompt $\psi$(2S) meson yield is found to be more suppressed than that of the prompt J/$\psi$ mesons in the entire p$_\mathrm{T}$ range.

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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.

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Evidence of b-jet quenching in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

The CMS collaboration Chatrchyan, Serguei ; Khachatryan, Vardan ; Sirunyan, Albert M ; et al.
Phys.Rev.Lett. 113 (2014) 132301, 2014.
Inspire Record 1269454 DOI 10.17182/hepdata.68931

The production of jets associated to bottom quarks is measured for the first time in PbPb collisions at a center-of-mass energy of 2.76 TeV per nucleon pair. Jet spectra are reported in the transverse momentum (pt) range of 80-250 GeV, and within pseudorapidity abs(eta < 2). The nuclear modification factor (R[AA]) calculated from these spectra shows a strong suppression in the b-jet yield in PbPb collisions relative to the yield observed in pp collisions at the same energy. The suppression persists to the largest values of pt studied, and is centrality dependent. The R[AA] is about 0.4 in the most central events, similar to previous observations for inclusive jets. This implies that jet quenching does not have a strong dependence on parton mass and flavor in the jet pt range studied.

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A Study of the Energy Dependence of the Underlying Event in Proton-Antiproton Collisions

The CDF collaboration Aaltonen, Timo Antero ; Amerio, Silvia ; Amidei, Dante E ; et al.
Phys.Rev.D 92 (2015) 092009, 2015.
Inspire Record 1388868 DOI 10.17182/hepdata.70787

We study charged particle production in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta-phi space; toward, away, and transverse. The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the underlying event. The transverse region is divided into a MAX and MIN transverse region, which helps separate the hard component (initial and final-state radiation) from the beam-beam remnant and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event are studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

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Evidence for color coherence in p anti-p collisions at s**(1/2) = 1.8-TeV

The CDF collaboration Abe, F. ; Albrow, Michael G. ; Amidei, Dante E. ; et al.
Phys.Rev.D 50 (1994) 5562-5579, 1994.
Inspire Record 374155 DOI 10.17182/hepdata.42448

Color coherence effects in pp¯ collisions are observed and studied with CDF, the Collider Detector at the Fermilab Tevatron collider. We demonstrate these effects by measuring spatial correlations between soft and leading jets in multijet events. Variables sensitive to interference are identified by comparing the data to the predictions of various shower Monte Carlo programs that are substantially different with respect to the implementation of coherence.

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Search for excited quarks in p anti-p collisions at s**(1/2) = 1.8-TeV

The CDF collaboration Abe, F. ; Albrow, Michael G. ; Amidei, Dante E. ; et al.
Phys.Rev.Lett. 72 (1994) 3004-3008, 1994.
Inspire Record 360332 DOI 10.17182/hepdata.42507

If quarks are composite particles then excited states are expected. We have searched in pp¯ collisions for excited quarks (q*) which decay to common quarks by emitting a W boson (q*→qW) or a photon (q*→qγ). The simplest model of excited quarks has been excluded for mass M*<540 GeV/c2 at 95% confidence level.

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Inclusive jet cross-section in anti-p p collisions at S**(1/2) = 1.8-TeV

The CDF collaboration Abe, F. ; Amidei, Dante E. ; Apollinari, G. ; et al.
Phys.Rev.Lett. 68 (1992) 1104-1108, 1992.
Inspire Record 319237 DOI 10.17182/hepdata.19883

We present a measurement of the inclusive jet cross section in p¯p collisions at √s =1.8 TeV at the Fermilab Tevatron using the Collider Detector at Fermilab. Good agreement is seen with the predictions of recent next-to-leading-order [O(αs3)] QCD predictions. The dependence of the cross section on clustering cone size is reported for the first time. An improved limit on Λc, a term characterizing possible quark substructure, is set at 1.4 TeV (95% C.L.).

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