Dielectron and heavy-quark production in inelastic and high-multiplicity proton-proton collisions at $\sqrt{s_{\rm NN}}$ = 13 TeV

The ALICE collaboration Acharya, Shreyasi ; Torales - Acosta, Fernando ; Adamova, Dagmar ; et al.
No Journal Information, 2018.
Inspire Record 1672788 DOI 10.17182/hepdata.85869

The measurement of dielectron production is presented as a function of invariant mass and transverse momentum ($p_{\rm T}$) at midrapidity ($|y_{\rm e}|<0.8$) in proton-proton (pp) collisions at a centre-of-mass energy of $\sqrt{s}=13$ TeV. The contributions from light-hadron decays are calculated from their measured cross sections in pp collisions at $\sqrt{s}=7$ TeV or 13 TeV. The remaining continuum stems from correlated semileptonic decays of heavy-flavour hadrons. Fitting the data with templates from two different MC event generators, PYTHIA and POWHEG, the charm and beauty cross sections at midrapidity are extracted for the first time at this collision energy: ${\rm d}\sigma_{\rm c\bar{c}}/{\rm d}y|_{y=0}=974\pm138(\rm{stat.})\pm140(\rm{syst.})~\mu{\rm b}$ and ${\rm d}\sigma_{\rm b\bar{b}}/{\rm d}y|_{y=0}=79\pm14(\rm{stat.})\pm11(\rm{syst.})~\mu{\rm b}$ using PYTHIA simulations and ${\rm d}\sigma_{\rm c\bar{c}}/{\rm d}y|_{y=0}=1417\pm184(\rm{stat.})\pm204(\rm{syst.})~\mu{\rm b}$ and ${\rm d}\sigma_{\rm b\bar{b}}/{\rm d}y|_{y=0}=48\pm14(\rm{stat.})\pm7(\rm{syst.})~\mu{\rm b}$ for POWHEG. These values, whose uncertainties are fully correlated between the two generators, are consistent with extrapolations from lower energies. The different results obtained with POWHEG and PYTHIA imply different kinematic correlations of the heavy-quark pairs in these two generators. Furthermore, comparisons of dielectron spectra in inelastic events and in events collected with a trigger on high charged-particle multiplicities are presented in various $p_{\rm T}$ intervals. The differences are consistent with the already measured scaling of light-hadron and open-charm production at high charged-particle multiplicity as a function of $p_{\rm T}$. Upper limits for the contribution of virtual direct photons are extracted at 90% confidence level and found to be in agreement with pQCD calculations.

16 data tables

The dielectron cross section in inelastic pp collisions at $\sqrt{s}$ = 13 TeV as a function of invariant mass for $p_{\rm T,ee}$ < 6.0 GeV/$c$.

The dielectron cross section in inelastic pp collisions at $\sqrt{s}$ = 13 TeV as a function of pair transverse momentum for $m_{\rm ee}$ < 0.14 GeV/$c^{2}$.

The dielectron cross section in inelastic pp collisions at $\sqrt{s}$ = 13 TeV as a function of pair transverse momentum for 0.14 < $m_{\rm ee}$ < 0.7 GeV/$c^{2}$.

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Dielectron production in proton-proton collisions at $\sqrt{s}$ = 7 TeV

The ALICE collaboration Acharya, Shreyasi ; Torales - Acosta, Fernando ; Adamova, Dagmar ; et al.
No Journal Information, 2018.
Inspire Record 1672792 DOI 10.17182/hepdata.83913

The first measurement of e$^+$e$^-$ pair production at mid-rapidity ($|\eta_{{\rm e}}|$ $<$ 0.8) in pp collisions at $\sqrt{s} = 7$ TeV with ALICE at the LHC is presented. The dielectron production is studied as a function of the invariant mass ($m_{\rm ee}$ $<$ 3.3 GeV/$c^{2}$), the pair transverse momentum ($p_{\rm T,ee}$ $<$ 8 GeV/$c$), and the pair transverse impact parameter (DCA$_{{\rm ee}}$), i.e., the average distance of closest approach of the reconstructed electron and positron tracks to the collision vertex, normalised to its resolution. The results are compared with the expectations from a cocktail of known hadronic sources and are well described when PYTHIA is used to generate the heavy-flavour contributions. In the low-mass region (0.14 $<$ $m_{\rm ee}$ $<$ 1.1 GeV/$c^{2}$), prompt and non-prompt e$^+$e$^-$ sources can be separated via the DCA$_{\rm ee}$. In the intermediate-mass region (1.1 $<$ $m_{\rm ee}$ $<$ 2.7 GeV/$c^{2}$), a double-differential fit to the data in $m_{\rm ee}$ and $p_{\rm T,ee}$ and a fit of the DCA$_{\rm ee}$ distribution allow the total ${\rm c\overline c}$ and ${\rm b\overline b}$ cross sections to be extracted. Two different event generators, PYTHIA and POWHEG, can reproduce the shape of the two-dimensional $m_{\rm ee}$ and $p_{\rm T,ee}$ spectra, as well as the shape of the DCA$_{\rm ee}$ distribution, reasonably well. However, differences in the ${\rm c\overline c}$ and ${\rm b\overline b}$ cross sections are observed when using the generators to extrapolate to full phase space. Finally, the ratio of inclusive to decay photons is studied via the measurement of virtual direct photons in the transverse-momentum range 1 $<$ $p_{\rm T}$ $<$ 8 GeV/$c$. This is found to be unity within the statistical and systematic uncertainties and consistent with expectations from next-to-leading order perturbative quantum chromodynamic calculations.

11 data tables

Inclusive $e^+e^-$ cross section in pp collisions at $\sqrt{s}$ = 7 TeV in the ALICE acceptance as a function of $m_{\rm ee}$.

Inclusive $e^+e^-$ cross section in pp collisions at $\sqrt{s}$ = 7 TeV in the ALICE acceptance as a function of $p_{\rm T,ee}$ for $m_{\rm ee}$ < 0.14 GeV/$c^{2}$.

Inclusive $e^+e^-$ cross section in pp collisions at $\sqrt{s}$ = 7 TeV in the ALICE acceptance as a function of $\rm DCA_{ee}$ for 0.08 < $m_{\rm ee}$ < 0.14 GeV/$c^{2}$.

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Forward–backward asymmetry of Drell–Yan lepton pairs in pp collisions at $\sqrt{s} = 8$ $\,\mathrm{TeV}$

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Eur.Phys.J. C76 (2016) 325, 2016.
Inspire Record 1415949 DOI 10.17182/hepdata.73121

A measurement of the forward–backward asymmetry ${A}_{\mathrm{FB}}$ of oppositely charged lepton pairs ( $\mu \mu $ and $\mathrm{e}\mathrm{e}$ ) produced via $\mathrm{Z}/\gamma ^*$ boson exchange in pp collisions at $\sqrt{s} = 8$ $\,\mathrm{TeV}$ is presented. The data sample corresponds to an integrated luminosity of 19.7 $\,\mathrm{fb}^{-1}$ collected with the CMS detector at the LHC. The measurement of ${A}_{\mathrm{FB}}$ is performed for dilepton masses between 40 $\,\text {GeV}$ and 2 $\,\mathrm{TeV}$ and for dilepton rapidity up to 5. The ${A}_{\mathrm{FB}}$ measurements as a function of dilepton mass and rapidity are compared with the standard model predictions.

40 data tables

Unfolded combined measurements of AFB in each M-|y| bin (mu+mu- and e+e- combined).

Unfolded measurement of AFB for the forward rapidity region (e+e-).

Unfolded measurements of AFB in each M-|y| bin (mu+mu-).

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Measurements of differential and double-differential Drell-Yan cross sections in proton-proton collisions at 8 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Eur.Phys.J. C75 (2015) 147, 2015.
Inspire Record 1332509 DOI 10.17182/hepdata.69869

Measurements of the differential and double-differential Drell–Yan cross sections in the dielectron and dimuon channels are presented. They are based on proton–proton collision data at $\sqrt{s} = 8\,\text {TeV} $ recorded with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 $\,\text {fb}^{-1}$ . The measured inclusive cross section in the $\mathrm{Z}$ peak region (60–120 $\,\text {GeV}$ ), obtained from the combination of the dielectron and dimuon channels, is $1138 \pm 8\,\text {(exp)} \pm 25\,\text {(theo)} \pm 30\,\text {(lumi)} \text {\,pb} $ , where the statistical uncertainty is negligible. The differential cross section $\mathrm{d}\sigma /\mathrm{d}{}m$ in the dilepton mass range 15–2000 $\,\text {GeV}$ is measured and corrected to the full phase space. The double-differential cross section $\mathrm{d}^2\sigma /\mathrm{d}{}m\,\mathrm{d}|y |$ is also measured over the mass range 20 to 1500 $\,\text {GeV}$ and absolute dilepton rapidity from 0 to 2.4. In addition, the ratios of the normalized differential cross sections measured at $\sqrt{s} = 7$ and 8 $\,\text {TeV}$ are presented. These measurements are compared to the predictions of perturbative QCD at next-to-leading and next-to-next-to-leading (NNLO) orders using various sets of parton distribution functions (PDFs). The results agree with the NNLO theoretical predictions computed with fewz 3.1 using the CT10 NNLO and NNPDF2.1 NNLO PDFs. The measured double-differential cross section and ratio of normalized differential cross sections are sufficiently precise to constrain the proton PDFs.

15 data tables

Absolute Drell-Yan cross section measurements in the Z peak region (60 < m < 120 GeV). The uncertainties in the measurements include the experimental and theoretical systematic sources and the uncertainty in the integrated luminosity. The statistical component is negligible.

The Drell-Yan differential pre-FSR cross section D(SIG)/DM as measured in the combined dilepton channel for the full phase space. Theoretical uncertainty on acceptance is included.

The Drell-Yan pre-FSR dilepton rapidity distribution D(SIG)/DABS(YRAP) within the detector acceptance, for the mass bin 20-30 GeV, as measured in the combined dilepton channel.

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Search for contact interactions and large extra dimensions in the dilepton channel using proton-proton collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
Eur.Phys.J. C74 (2014) 3134, 2014.
Inspire Record 1305430 DOI 10.17182/hepdata.65760
10 data tables

Reconstructed dielectron mass distributions for data and the SM background estimate.

Reconstructed dimuon mass distributions for data and the SM background estimate.

Reconstructed $\cos\theta^*$ distributions for data and the SM background estimate in the dielectron channel.

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Measurement of the differential and double-differential Drell-Yan cross sections in proton-proton collisions at $\sqrt{s} =$ 7 TeV

The CMS collaboration Chatrchyan, Serguei ; Khachatryan, Vardan ; Sirunyan, Albert M ; et al.
JHEP 1312 (2013) 030, 2013.
Inspire Record 1262319 DOI 10.17182/hepdata.62207

Measurements of the differential and double-differential Drell-Yan cross sections are presented using an integrated luminosity of 4.5(4.8) inverse femtobarns in the dimuon (dielectron) channel of proton-proton collision data recorded with the CMS detector at the LHC at $\sqrt{s}$ = 7 TeV. The measured inclusive cross section in the Z-peak region (60-120 GeV) is $\sigma(\ell \ell)$ = 986.4 +/- 0.6 (stat.) +/- 5.9 (exp. syst.) +/- 21.7 (th. syst.) +/- 21.7 (lum.) pb for the combination of the dimuon and dielectron channels. Differential cross sections $d\sigma/dm$ for the dimuon, dielectron, and combined channels are measured in the mass range 15 to 1500 GeV and corrected to the full phase space. Results are also presented for the measurement of the double-differential cross section $d^2\sigma/dm d |y|$ in the dimuon channel over the mass range 20 to 1500 GeV and absolute dimuon rapidity from 0 to 2.4. These measurements are compared to the predictions of perturbative QCD calculations at next-to-leading and next-to-next-to-leading orders using various sets of parton distribution functions.

10 data tables

Normalization factors for the cross section measurements from the Z-peak region (60 < M < 120 GeV) with associated uncertainties. The measurements are given in the muon, electron and combined channels. The three systematic uncertainties correspond to experimental, theoretical and luminosity.

The DY cross section measurements for the muon channel normalized to the Z-peak region, pre- and post-FSR, as measured in the full acceptance and for the CMS detector acceptance. The uncertainty indicates the experimental (statistical and systematic) uncertainties summed in quadrature with the theoretical uncertainty resulting from the model-dependent kinematic distributions inside each bin.

The DY cross section measurements for the electron channel normalized to the Z-peak region, pre- and post-FSR, as measured in the full acceptance and for the CMS detector acceptance. The uncertainty indicates the experimental (statistical and systematic) uncertainties summed in quadrature with the theoretical uncertainty resulting from the model-dependent kinematic distributions inside each bin.

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Search for contact interactions and large extra dimensions in dilepton events from $pp$ collisions at $\sqrt{s}=7$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abajyan, Tatevik ; Abbott, Brad ; et al.
Phys.Rev. D87 (2013) 015010, 2013.
Inspire Record 1198341 DOI 10.17182/hepdata.60277

A search for non-resonant new phenomena, originating from either contact interactions or large extra spatial dimensions, has been carried out using events with two isolated electrons or muons. These events, produced at the LHC in proton-proton collisions at sqrt(s) = 7 TeV, were recorded by the ATLAS detector. The data sample, collected throughout 2011, corresponds to an integrated luminosity of 4.9 and 5.0 fb-1 in the e+e- and mu+mu- channels, respectively. No significant deviations from the Standard Model expectation are observed. Using a Bayesian approach, 95% confidence limit lower limits ranging from 9.0 to 13.9 TeV are placed on the energy scale of llqq contact interactions in the left-left isoscalar model. Lower limits ranging from 2.4 to 3.9 TeV are also set on the string scale in large extra dimension models. After combination of these limits with results from a similar search in the diphoton channel, slightly more stringent limits are obtained.

7 data tables

Expected and observed numbers of events in the dielectron channel for the contact interactions search region. The yields are normalized to the Z peak control region and include predictions for SM backgrounds as well as for SM+CI with different CI scales for constructive (LAMBDA-) and destructive (LAMBDA+) interference. The errors quoted originate from both systematic uncertainties and limited MC statistics.

Expected and observed numbers of events in the dimuon channel for the contact interactions search region. The yields are normalized to the Z peak control region and include predictions for SM backgrounds as well as for SM+CI with different CI scales for constructive (LAMBDA-) and destructive (LAMBDA+) interference. The errors quoted originate from both systematic uncertainties and limited MC statistics.

Expected and observed 95% C.L. lower limits on the contact interaction energy scale LAMBDA for the dielectron and dimuon channels, as well as for the combination of those channels. Results are provided for constructive and destruc- tive interference as well as different choices of flat priors.

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Search for high-mass resonances decaying to dilepton final states in pp collisions at s**(1/2) = 7-TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abajyan, Tatevik ; Abbott, Brad ; et al.
JHEP 1211 (2012) 138, 2012.
Inspire Record 1185259 DOI 10.17182/hepdata.59903
14 data tables

Expected and observed number of events in the dielectron channel. The errors quoted include both statistical and systematic uncertainties.

Expected and observed number of events in the dimuon channel. The errors quoted include both statistical and systematic uncertainties.

Observed and predicted dielectron invariant mass (m_ee) distribution in the search region. The bin width is constant in log(m_ee).

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Measurement of the Drell-Yan Cross Section in $pp$ Collisions at $\sqrt{s}=7$ TeV

The CMS collaboration Chatrchyan, Serguei ; Khachatryan, Vardan ; Sirunyan, Albert M ; et al.
JHEP 1110 (2011) 007, 2011.
Inspire Record 921788 DOI 10.17182/hepdata.57980

The Drell-Yan differential cross section is measured in pp collisions at sqrt(s) = 7 TeV, from a data sample collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 36 inverse picobarns. The cross section measurement, normalized to the measured cross section in the Z region, is reported for both the dimuon and dielectron channels in the dilepton invariant mass range 15-600 GeV. The normalized cross section values are quoted both in the full phase space and within the detector acceptance. The effect of final state radiation is also identified. The results are found to agree with theoretical predictions.

3 data tables

The DY spectrum normalized to the Z0 region and to the mass bin widths.

The DY spectrum normalized to the Z0 region for the dimuon channel. Results are for within the detector acceptance(DET) and full phase space both before (POST-FSR) and after final state raduiation corrections.

The DY spectrum normalized to the Z0 region for the dielectron channel. Results are for within the detector acceptance(DET) and full phase space both before (POST-FSR) and after final state raduiation corrections.


Mass and transverse momentum dependence of dielectron production in p + d and p + p collisions at 4.9-GeV

The DLS collaboration Huang, H.Z. ; Beedoe, S. ; Bougteb, M. ; et al.
Phys.Rev. C49 (1994) 314-319, 1994.
Inspire Record 356615 DOI 10.17182/hepdata.38156
8 data tables

Mass distribution.

Mass distribution.

Transverse momentum distribution.

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Dielectron yields in p + d and p + p collisions at 4.9-GeV

Huang, H.Z. ; Beedoe, S. ; Bougteb, M. ; et al.
Phys.Lett. B297 (1992) 233-237, 1992.
Inspire Record 338830 DOI 10.17182/hepdata.28996
2 data tables

Background subtracted data uncorrected for acceptance.

Background subtracted data uncorrected for acceptance.


Dielectron measurements in p + p and p + d interactions from E (beam) = 1-GeV to 4.9-GeV

The DLS collaboration Wilson, W.K. ; Beedoe, S. ; Bougteb, M. ; et al.
Phys.Lett. B316 (1993) 245-249, 1993.
Inspire Record 358344 DOI 10.17182/hepdata.28808
7 data tables

No description provided.

No description provided.

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A Study of massive electron pairs and associated particles produced at the CERN ISR

The CERN-Michigan State-Oxford-Rockefeller collaboration Angelis, A.L.S. ; Basini, G. ; Besch, H.J. ; et al.
Nucl.Phys. B348 (1991) 1-22, 1991.
Inspire Record 298427 DOI 10.17182/hepdata.33054
3 data tables

No description provided.

No description provided.

No description provided.