Determination of Z0 resonance parameters and couplings from its hadronic and leptonic decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.
Nucl.Phys.B 367 (1991) 511-574, 1991.
Inspire Record 317493 DOI 10.17182/hepdata.33016

From measurements of the cross sections for e + e − → hadrons and the cross sections and forward-backward charge-asymmetries for e e −→ e + e − , μ + μ − and π + π − at several centre-of-mass energies around the Z 0 pole with the DELPHI apparatus, using approximately 150 000 hadronic and leptonic events from 1989 and 1990, one determines the following Z 0 parameters: the mass and total width M Z = 91.177 ± 0.022 GeV, Γ Z = 2.465 ± 0.020 GeV , the hadronic and leptonic partial widths Γ h = 1.726 ± 0.019 GeV, Γ l = 83.4 ± 0.8 MeV, the invisible width Γ inv = 488 ± 17 MeV, the ratio of hadronic over leptonic partial widths R Z = 20.70 ± 0.29 and the Born level hadronic peak cross section σ 0 = 41.84±0.45 nb. A flavour-independent measurement of the leptonic cross section gives very consistent results to those presented above ( Γ l = 83.7 ± 0.8 rmMeV ). From these results the number of light neutrino species is determined to be N v = 2.94 ±0.10. The individual leptonic widths obtained are: Γ e = 82.4±_1.2 MeV, Γ u = 86.9±2.1 MeV and Γ τ = 82.7 ± 2.4 MeV. Assuming universality, the squared vector and axial-vector couplings of the Z 0 to charged leptons are: V ̄ l 2 = 0.0003±0.0010 and A ̄ l 2 = 0.2508±0.0027 . These values correspond to the electroweak parameters: ϱ eff = 1.003 ± 0.011 and sin 2 θ W eff = 0.241 ± 0.009. Within the Minimal Standard Model (MSM), the results can be expressed in terms of a single parameter: sin 2 θ W M ̄ S = 0.2338 ± 0.0027 . All these values are in good agreement with the predictions of the MSM. Fits yield 43< m top < 215 GeV at the 95% level. Finally, the measured values of Γ Z and Γ inv are used to derived lower mass bounds for possible new particles.

1 data table match query

Cross section from analysis I based on energy of charged particles. Additional 1.0 pct normalisation uncertainty.


Determination of $alpha_{s}$ in second order {QCD} from hadronic $Z$ decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.
Z.Phys.C 54 (1992) 55-74, 1992.
Inspire Record 333272 DOI 10.17182/hepdata.14603

Distributions of event shape variables obtained from 120600 hadronicZ decays measured with the DELPHI detector are compared to the predictions of QCD based event generators. Values of the strong coupling constant αs are derived as a function of the renormalization scale from a quantitative analysis of eight hadronic distributions. The final result, αs(MZ), is based on second order perturbation theory and uses two hadronization corrections, one computed with a parton shower model and the other with a QCD matrix element model.

2 data tables match query

The energy-energy correlation EEC as a function of the correlation angle CHI.

The energy-energy correlation EEC as a function of the correlation angle CHI.


Determination of alpha-s using the next-to-leading log approximation of QCD

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Z.Phys.C 59 (1993) 21-34, 1993.
Inspire Record 354909 DOI 10.17182/hepdata.50115

A new measurement of αs is obtained from the distributions in thrust, heavy jet mass, energy-energy correlation and two recently introduced jet broadening variables following a method proposed by Cata

1 data table match query

Distribution of the back-to-back energy-energy correlation (EEC) corrected for detector acceptance and initial state photon radiation.


Measurements of the line shape of the Z0 and determination of electroweak parameters from its hadronic and leptonic decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Nucl.Phys.B 417 (1994) 3-57, 1994.
Inspire Record 372144 DOI 10.17182/hepdata.48413

During the LEP running periods in 1990 and 1991 DELPHI has accumulated approximately 450 000 Z 0 decays into hadrons and charged leptons. The increased event statistics coupled with improved analysis techniques and improved knowledge of the LEP beam energies permit significantly better measurements of the mass and width of the Z 0 resonance. Model independent fits to the cross sections and leptonic forward- backward asymmetries yield the following Z 0 parameters: the mass and total width M Z = 91.187 ± 0.009 GeV, Γ Z = 2.486 ± 0.012 GeV, the hadronicf and leptonic partials widths Γ had = 1.725 ± 0.012 GeV, Γ ℓ = 83.01 ± 0.52 MeV, the invisible width Γ inv = 512 ± 10 MeV, the ratio of hadronic to leptonic partial widths R ℓ = 20.78 ± 0.15, and the Born level hadronic peak cross section σ 0 = 40.90 ± 0.28 nb. Using these results and the value of α s determined from DELPHI data, the number of light neutrino species is determined to be 3.08 ± 0.05. The individual leptonic widths are found to be: Γ e = 82.93 ± 0.70 MeV, Γ μ = 83.20 ± 1.11 MeV and Γ τ = 82.89 ± 1.31 MeV. Using the measured leptonic forward-backward asymmetries and assuming lepton universality, the squared vector and axial-vector couplings of the Z 0 to charged leptons are found to be g V ℓ 2 = (1.47 ± 0.51) × 10 −3 and g A ℓ 2 = 0.2483 ± 0.0016. A full Standard Model fit to the data yields a value of the top mass m t = 115 −82 +52 (expt.) −24 +52 (Higgs) GeV, corresponding to a value of the weak mixing angle sin 2 θ eff lept = 0.2339±0.0015 (expt.) −0.0004 +0.0001 (Higgs). Values are obtained for the variables S and T , or ϵ 1 and ϵ 3 which parameterize electroweak loop effects.

1 data table match query

LEPTON+ LEPTON- cross sections from the 1990 data set. Data are corrected for t-channel subtraction, and to full solid angle but not for momenta and accollinearity cuts. Additional systematic uncertainty, excluding luminosity, is 0.6 pct.


Measurement of the e+ e- ---> gamma gamma (gamma) cross-section at LEP energies

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Phys.Lett.B 327 (1994) 386-396, 1994.
Inspire Record 373116 DOI 10.17182/hepdata.48343

The total and the differential cross sections for the reaction e + e − → γγ ( γ ) have been measured with the DELPHI detector at LEP using an integrated luminosity of 36.9 pb −1 . The results agree with the QED predictions and consequently there is no evidence for non-standard channels with the same experimental signature. The lower limits obtained on the QED cutoff parameters are Λ + > 143 GeV and Λ − > 120 GeV, and the lower bound on the mass of an excited electron with an effective coupling constant λ γ = 1 is 132 GeV/ c 2 . Upper limits on the branching ratios for the decays Z 0 → γγ , Z 0 → π 0 γ , Z 0 → ηγ and Z 0 → γγγ have been determined to be 5.5 × 10 −5 , 5.5 × 10 −5 , 8.0 × 10 −5 , and 1.7 × 10 −5 respectively. All the limits are at the 95% confidence level.

1 data table match query

1990 energies are 88.223, 89.222, 90.217, 91.217, 92.209, 93.208 and 94.202 GeV.. 1991 energies are 88.465, 89.460, 90.208, 91.225, 91.954, 92.953, and 93.703 GeV.. 1992 energy is 91.278 GeV.


Tuning and test of fragmentation models based on identified particles and precision event shape data.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Z.Phys.C 73 (1996) 11-60, 1996.
Inspire Record 424112 DOI 10.17182/hepdata.47800

Event shape and charged particle inclusive distributions are measured using 750000 decays of the Z to hadrons from the DELPHI detector at LEP. These precise data allow a decisive confrontation with models of the hadronization process. Improved tunings of the JETSET, ARIADNE and HERWIG parton shower models and the JETSET matrix element model are obtained by fitting the models to these DELPHI data as well as to identified particle distributions from all LEP experiments. The description of the data distributions by the models is critically reviewed with special importance attributed to identified particles.

3 data tables match query

Difference in Hemisphere Masses. Corrected to final state particles.

Energy-Energy Correlation EEC. Corrected to final state particles.

Asymmetry of the Energy-Energy Correlation AEEC. Corrected to final state particles.


Measurement of event shape and inclusive distributions at s**(1/2) = 130-GeV and 136-GeV.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Z.Phys.C 73 (1997) 229-242, 1997.
Inspire Record 424629 DOI 10.17182/hepdata.47715

Inclusive charged particle and event shape distributions are measured using 321 hadronic events collected with the DELPHI experiment at LEP at effective centre of mass energies of 130 to 136 GeV. These distributions are presented and compared to data at lower energies, in particular to the precise Z data. Fragmentation models describe the observed changes of the distributions well. The energy dependence of the means of the event shape variables can also be described using second order QCD plus power terms. A method independent of fragmentation model corrections is used to determine αs from the energy dependence of the mean thrust and heavy jet mass. It is measured to be: $$←pha _s(133 {⤪ GeV})={0.116}pm {0.007}_{exp-0.004theo}^{+0.005}$$ from the high energy data.

1 data table match query

5-jet rate for the Durham Algorithm.


Investigation of the splitting of quark and gluon jets.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J.C 4 (1998) 1-17, 1998.
Inspire Record 467927 DOI 10.17182/hepdata.49547

The splitting processes in identified quark and gluon jets are investigated using longitudinal and transverse observables. The jets are selected from symmetric three-jet events measured in Z decays with the Delphi detector in 1991-1994. Gluon jets are identified using heavy quark anti-tagging. Scaling violations in identified gluon jets are observed for the first time. The scale energy dependence of the gluon fragmentation function is found to be about two times larger than for the corresponding quark jets, consistent with the QCD expectation CA/CF. The primary splitting of gluons and quarks into subjets agrees with fragmentation models and, for specific regions of the jet resolution y, with NLLA calculations. The maximum of the ratio of the primary subjet splittings in quark and gluon jets is 2.77±0.11±0.10. Due to non-perturbative effects, the data are below the expectation at small y. The transition from the perturbative to the non-perturbative domain appears at smaller y for quark jets than for gluon jets. Combined with the observed behaviour of the higher rank splittings, this explains the relatively small multiplicity ratio between gluon and quark jets.

4 data tables match query

Scaled energy distribution of charged hadrons produced in Quark jets in 'Y'topology 3-JET events.

Scaled energy distribution of charged hadrons produced in Gluon jets in 'Y'topology 3-JET events.

Scaled energy distribution of charged hadrons produced in Quark jets in 'Mercedes' topology 3-JET events.

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pi+-, K+-, p and anti-p production in Z0 --> q anti-q, Z0 --> b anti-b, Z0 --> u anti-u, d anti-d, s anti-s.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J.C 5 (1998) 585-620, 1998.
Inspire Record 473409 DOI 10.17182/hepdata.49385

The DELPHI experiment at LEP uses Ring Imaging Cherenkov detectors for particle identification. The good understanding of the RICH detectors allows the identification of charged pions, kaons and proto

1 data table match query

Differential cross section for P PBAR in Z0-->Q-QBAR events.


The scale dependence of the hadron multiplicity in quark and gluon jets and a precise determination of C(A)/C(F).

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Phys.Lett.B 449 (1999) 383-400, 1999.
Inspire Record 495414 DOI 10.17182/hepdata.49173

Data collected at the Z resonance using the DELPHI detector at LEP are used to determine the charged hadron multiplicity in gluon and quark jets as a function of a transverse momentum-like scale. The colour factor ratio, \cacf, is directly observed in the increase of multiplicities with that scale. The smaller than expected multiplicity ratio in gluon to quark jets is understood by differences in the hadronization of the leading quark or gluon. From the dependence of the charged hadron multiplicity on the opening angle in symmetric three-jet events the colour factor ratio is measured to be: C_A/C_F = 2.246 \pm 0.062 (stat.) \pm 0.080 (syst.) \pm 0.095 (theo.)

1 data table match query

Charged multiplicity in events with a hard photon, as a function of the apparent centre-of-mass energy (SQRT(S)) of the hadronic system. The errors shown are statistical only.


Energy dependence of event shapes and of alpha(s) at LEP-2.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Phys.Lett.B 456 (1999) 322-340, 1999.
Inspire Record 499183 DOI 10.17182/hepdata.49129

Infrared and collinear safe event shape distributions and their mean values are determined using the data taken at five different centre of mass energies above M Z with the DELPHI detector at LEP. From the event shapes, the strong coupling α s is extracted in O ( α s 2 ), NLLA and a combined scheme using hadronisation corrections evaluated with fragmentation model generators as well as using an analytical power ansatz. Comparing these measurements to those obtained at M Z , the energy dependence (running) of α s is accessible. The logarithmic energy slope of the inverse strong coupling is measured to be d α −1 s d log (E cm ) =1.39±0.34( stat )±0.17( syst ) , in good agreement with the QCD expectation of 1.27.

17 data tables match query

Distribution of (1-THRUST) at cm energy 183 GeV.

Distribution of Thrust Major (MAJOR) at cm energy 183 GeV.

Distribution of Thrust Minor (MINOR) at cm energy 183 GeV.

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Consistent measurements of alpha(s) from precise oriented event shape distributions.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J.C 14 (2000) 557-584, 2000.
Inspire Record 522656 DOI 10.17182/hepdata.13245

An updated analysis using about 1.5 million events recorded at $\sqrt{s} = M_Z$ with the DELPHI detector in 1994 is presented. Eighteen infrared and collinear safe event shape observables are measured as a function of the polar angle of the thrust axis. The data are compared to theoretical calculations in ${\cal O} (\alpha_s^2)$ including the event orientation. A combined fit of $\alpha_s$ and of the renormalization scale $x_{\mu}$ in $\cal O(\alpha_s^2$) yields an excellent description of the high statistics data. The weighted average from 18 observables including quark mass effects and correlations is $\alpha_s(M_Z^2) = 0.1174 \pm 0.0026$. The final result, derived from the jet cone energy fraction, the observable with the smallest theoretical and experimental uncertainty, is $\alpha_s(M_Z^2) = 0.1180 \pm 0.0006 (exp.) \pm 0.0013 (hadr.) \pm 0.0008 (scale) \pm 0.0007 (mass)$. Further studies include an $\alpha_s$ determination using theoretical predictions in the next-to-leading log approximation (NLLA), matched NLLA and $\cal O(\alpha_s^2$) predictions as well as theoretically motivated optimized scale setting methods. The influence of higher order contributions was also investigated by using the method of Pad\'{e} approximants. Average $\alpha_s$ values derived from the different approaches are in good agreement.

15 data tables match query

Energy Energy Correlation EEC.

Asymmetry of the Energy Energy Correlation AEEC.

Jet Cone Energy Fraction.

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Cross-sections and leptonic forward-backward asymmetries from the Z0 running of LEP.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J.C 16 (2000) 371-405, 2000.
Inspire Record 527605 DOI 10.17182/hepdata.49969

During 1993 and 1995 LEP was run at 3 energies near the Z$^0$peak in order to give improved measurements of the mass and width of the resonance. During 1994, LEP o

1 data table match query

Measurement of the observed Born cross section for the 1992-1995 data from the ISR events. SPRIME is the reduced energy after the ISR.


Charged and Identified Particles in the Hadronic Decay of W Bosons and in e+e- -> q qbar from 130 to 200 GeV

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J.C 18 (2000) 203-228, 2000.
Inspire Record 526164 DOI 10.17182/hepdata.43294

Inclusive distributions of charged particles in hadronic W decays are experimentally investigated using the statistics collected by the DELPHI experiment at LEP during 1997, 1998 and 1999, at centre-of-mass energies from 183 to around 200 GeV. The possible effects of interconnection between the hadronic decays of two Ws are not observed. Measurements of the average multiplicity for charged and identified particles in q qbar and WW events at centre-of-mass energies from 130 to 200 GeV and in W decays are presented. The results on the average multiplicity of identified particles and on the position xi^* of the maximum of the xi_p = -log(2p/sqrt(s)) distribution are compared with predictions of JETSET and MLLA calculations.

12 data tables match query

Average multiplicities of identified hadrons produced in fully hadronic (4Q) and semi-leptonic (2Q) W decays at a centre-of-mass energy of 189 GeV.

Corrected momentum distributions of charged particles for 4Q and 2Q events at a centre-of-mass energy 189 GeV.

The difference (4Q-2*2Q) between the fully hadronic and semileptonic momentum distributions at a centre-of-mass energy 189 GeV.

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Determination of the e+ e- --> gamma gamma (gamma) cross-section at centre-of-mass energies ranging from 189-GeV to 202-GeV.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Phys.Lett.B 491 (2000) 67-80, 2000.
Inspire Record 534257 DOI 10.17182/hepdata.49880

A test of the QED process e+e- -> gamma gamma (gamma) is reported. The data analysed were collected with the DELPHI detector in 1998 and 1999 at the highest energies achieved at LEP, reaching 202 GeV in the centre-of-mass. The total integrated luminosity amounts to 375.7 pb^{-1}. The differential and total cross-sections for the process e+e- -> gamma gamma were measured, and found to be in agreement with the QED prediction. 95% Confidence Level (C.L.) lower limits on the QED cut-off parameters of Lambda+ > 330 GeV and Lambda- > 320 GeV were derived. A 95% C.L. lower bound on the mass of an excited electron of 311 GeV/c^2 (for lambda_gamma = 1) was obtained. s-channel virtual graviton exchange was searched for, resulting in 95% C.L. lower limits on the string mass scale, M_S: M_S > 713 GeV/c^2 (lambda = 1) and M_S > 691 GeV/c^2 (lambda = -1).

2 data tables match query

The results for the energy of 193.8 GeV (C=COMBINED) are obtained by combining of the data sets from all energies.

The results for the energy of 193.8 GeV (C=COMBINED) are obtained by combining of the data sets from all energies.


A study of the energy evolution of event shape distributions and their means with the DELPHI detector at LEP.

The DELPHI collaboration Abdallah, J. ; Abreu, P. ; Adam, W. ; et al.
Eur.Phys.J.C 29 (2003) 285-312, 2003.
Inspire Record 620250 DOI 10.17182/hepdata.13029

Infrared and collinear safe event shape distributions and their mean values are determined in e+e- collisions at centre-of-mass energies between 45 and 202 GeV. A phenomenological analysis based on power correction models including hadron mass effects for both differential distributions and mean values is presented. Using power corrections, alpha_s is extracted from the mean values and shapes. In an alternative approach, renormalisation group invariance (RGI) is used as an explicit constraint, leading to a consistent description of mean values without the need for sizeable power corrections. The QCD beta-function is precisely measured using this approach. From the DELPHI data on Thrust, including data from low energy experiments, one finds beta_0 = 7.86 +/- 0.32 for the one loop coefficient of the beta-function or, assuming QCD, n_f = 4.75 +/- 0.44 for the number of active flavours. These values agree well with the QCD expectation of beta_0=7.67 and n_f=5. A direct measurement of the full logarithmic energy slope excludes light gluinos with a mass below 5 GeV.

3 data tables match query

Integrated Jet Cone Energy Fractions (JCEF) for different anglular intervals.

Integrated values of the Energy Energy Correlations (EEC) for different angular intervals.

Integrated values of the Energy Energy Correlations Asymmetry (AEEC) for different angular intervals.


Measurement and interpretation of fermion-pair production at LEP energies above the Z resonance.

The DELPHI collaboration Abdallah, J. ; Abreu, P. ; Adam, W. ; et al.
Eur.Phys.J.C 45 (2006) 589-632, 2006.
Inspire Record 699726 DOI 10.17182/hepdata.48590

This paper presents DELPHI measurements and interpretations of cross-sections, forward-backward asymmetries, and angular distributions, for the e+e- -> ffbar process for centre-of-mass energies above the Z resonance, from sqrt(s) ~ 130 - 207 GeV at the LEP collider. The measurements are consistent with the predictions of the Standard Model and are used to study a variety of models including the S-Matrix ansatz for e+e- -> ffbar scattering and several models which include physics beyond the Standard Model: the exchange of Z' bosons, contact interactions between fermions, the exchange of gravitons in large extra dimensions and the exchange of sneutrino in R-parity violating supersymmetry.

23 data tables match query

Differential cross sections for non-radiative E+ E- --> E+ E- events at centre of mass energy 189 GeV.

Differential cross sections for non-radiative E+ E- --> E+ E- events at centre of mass energy 192 GeV.

Differential cross sections for non-radiative E+ E- --> E+ E- events at centre of mass energy 196 GeV.

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Di-jet production in gamma-gamma collisions at LEP2

The DELPHI collaboration Abdallah, J. ; Abreu, P. ; Adam, W. ; et al.
Eur.Phys.J.C 58 (2008) 531-541, 2008.
Inspire Record 806241 DOI 10.17182/hepdata.51688

The production of two high-p_T jets in the interactions of quasi-real photons in e+e- collisions at sqrt{s_ee} from 189 GeV to 209 GeV is studied with data corresponding to an integrated e+e- luminosity of 550 pb^{-1}. The jets reconstructed by the k_T cluster algorithm are defined within the pseudo-rapidity range -1 < eta < 1 and with jet transverse momentum, p_T, above 3 GeV/c. The differential di-jet cross-section is measured as a function of the mean transverse momentum ptmean of the jets and is compared to perturbative QCD calculations.

4 data tables match query

Distribution of the total energy outside the reconstructed jets for the completed data samples. Also tabulated is the estimated background.

Distribution of the total energy outside the reconstructed jets for the 'Dir' domain. Also tabulated is the estimated background.

Distribution of the total energy outside the reconstructed jets for the 'SR' domain. Also tabulated is the estimated background.

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Transverse momentum and pseudorapidity distributions of charged hadrons in pp collisions at sqrt(s) = 0.9 and 2.36 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M. ; Tumasyan, Armen ; et al.
JHEP 02 (2010) 041, 2010.
Inspire Record 845323 DOI 10.17182/hepdata.54829

Measurements of inclusive charged-hadron transverse-momentum and pseudorapidity distributions are presented for proton-proton collisions at sqrt(s) = 0.9 and 2.36 TeV. The data were collected with the CMS detector during the LHC commissioning in December 2009. For non-single-diffractive interactions, the average charged-hadron transverse momentum is measured to be 0.46 +/- 0.01 (stat.) +/- 0.01 (syst.) GeV/c at 0.9 TeV and 0.50 +/- 0.01 (stat.) +/- 0.01 (syst.) GeV/c at 2.36 TeV, for pseudorapidities between -2.4 and +2.4. At these energies, the measured pseudorapidity densities in the central region, dN(charged)/d(eta) for |eta| < 0.5, are 3.48 +/- 0.02 (stat.) +/- 0.13 (syst.) and 4.47 +/- 0.04 (stat.) +/- 0.16 (syst.), respectively. The results at 0.9 TeV are in agreement with previous measurements and confirm the expectation of near equal hadron production in p-pbar and pp collisions. The results at 2.36 TeV represent the highest-energy measurements at a particle collider to date.

6 data tables match query

Measured differential yield of charged hadrons as a function of transverse momentum for pseudorapidities 0.1, 0.3, 0.5 and 0.7 for centre-of-mass energy 900 GeV.

Measured differential yield of charged hadrons as a function of transverse momentum for pseudorapidities 0.9, 1.1, 1.3 and 1.5 for centre-of-mass energy 900 GeV.

Measured differential yield of charged hadrons as a function of transverse momentum for pseudorapidities 1.7, 1.9, 2.1 and 2.3 for centre-of-mass energy 900 GeV.

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Measurement of inclusive jet and dijet cross sections in proton-proton collisions at 7 TeV centre-of-mass energy with the ATLAS detector

The ATLAS collaboration Aad, G. ; Abbott, B. ; Abdallah, J. ; et al.
Eur.Phys.J.C 71 (2011) 1512, 2011.
Inspire Record 871366 DOI 10.17182/hepdata.56004

Jet cross sections have been measured for the first time in proton-proton collisions at a centre-of-mass energy of 7 TeV using the ATLAS detector. The measurement uses an integrated luminosity of 17 nb-1 recorded at the Large Hadron Collider. The anti-kt algorithm is used to identify jets, with two jet resolution parameters, R = 0.4 and 0.6. The dominant uncertainty comes from the jet energy scale, which is determined to within 7% for central jets above 60 GeV transverse momentum. Inclusive single-jet differential cross sections are presented as functions of jet transverse momentum and rapidity. Dijet cross sections are presented as functions of dijet mass and the angular variable $\chi$. The results are compared to expectations based on next-to-leading-order QCD, which agree with the data, providing a validation of the theory in a new kinematic regime.

1 data table match query

Dijet double-differential cross sections in the |rapidity(max)| range 520 to 800, using a jet resolution R value of 0.4. The four (sys) errors are respectively, the Absolute JES, the Relative JES, the Unfolding and the Luminosity uncertainties.


Measurement of the W -> lnu and Z/gamma* -> ll production cross sections in proton-proton collisions at sqrt(s) = 7 TeV with the ATLAS detector

The ATLAS collaboration Aad, G. ; Abbott, B. ; Abdallah, J. ; et al.
JHEP 12 (2010) 060, 2010.
Inspire Record 872570 DOI 10.17182/hepdata.56744

First measurements of the W -> lnu and Z/gamma* -> ll (l = e, mu) production cross sections in proton-proton collisions at sqrt(s) = 7 TeV are presented using data recorded by the ATLAS experiment at the LHC. The results are based on 2250 W -> lnu and 179 Z/gamma* -> ll candidate events selected from a data set corresponding to an integrated luminosity of approximately 320 nb-1. The measured total W and Z/gamma*-boson production cross sections times the respective leptonic branching ratios for the combined electron and muon channels are $\stotW$ * BR(W -> lnu) = 9.96 +- 0.23(stat) +- 0.50(syst) +- 1.10(lumi) nb and $\stotZg$ * BR(Z/gamma* -> ll) = 0.82 +- 0.06(stat) +- 0.05(syst) +- 0.09(lumi) nb (within the invariant mass window 66 < m_ll < 116 GeV). The W/Z cross-section ratio is measured to be 11.7 +- 0.9(stat) +- 0.4(syst). In addition, measurements of the W+ and W- production cross sections and of the lepton charge asymmetry are reported. Theoretical predictions based on NNLO QCD calculations are found to agree with the measurements.

1 data table match query

Measured total cross-section ratio R_{W-/Z} = sigma (W- -> e- nubar) / sigma (Z/gamma^* -> e+ e-).


Measurement of the inclusive isolated prompt photon cross section in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The ATLAS collaboration Aad, G. ; Abbott, B. ; Abdallah, J. ; et al.
Phys.Rev.D 83 (2011) 052005, 2011.
Inspire Record 882463 DOI 10.17182/hepdata.57465

A measurement of the cross section for the inclusive production of isolated prompt photons in pp collisions at a centre-of-mass energy sqrt(s) = 7TeV is presented. The measurement covers the pseudorapidity ranges |eta|<1.37 and 1.52<|eta|<1.81 in the transverse energy range 15 < E_T <100 GeV. The results are based on an integrated luminosity of 880 nb-1, collected with the ATLAS detector at the Large Hadron Collider. Photon candidates are identified by combining information from the calorimeters and from the inner tracker. Residual background in the selected sample is estimated from data based on the observed distribution of the transverse isolation energy in a narrow cone around the photon candidate. The results are compared to predictions from next-to-leading order perturbative QCD calculations.

3 data tables match query

The measured prompt photon cross section as a function of transverse energy for the |pseudorapidity| range < 0.6.

The measured prompt photon cross section as a function of transverse energy for the |pseudorapidity| range 0.6 to 1.37.

The measured prompt photon cross section as a function of transverse energy for the |pseudorapidity| range 1.52 to 1.81.


Charged-particle multiplicities in pp interactions measured with the ATLAS detector at the LHC

The ATLAS collaboration Aad, G. ; Abbott, B. ; Abdallah, J. ; et al.
New J.Phys. 13 (2011) 053033, 2011.
Inspire Record 882098 DOI 10.17182/hepdata.57077

Measurements are presented from proton-proton collisions at centre-of-mass energies of sqrt(s) = 0.9, 2.36 and 7 TeV recorded with the ATLAS detector at the LHC. Events were collected using a single-arm minimum-bias trigger. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity and the relationship between the mean transverse momentum and charged-particle multiplicity are measured. Measurements in different regions of phase-space are shown, providing diffraction-reduced measurements as well as more inclusive ones. The observed distributions are corrected to well-defined phase-space regions, using model-independent corrections. The results are compared to each other and to various Monte Carlo models, including a new AMBT1 PYTHIA 6 tune. In all the kinematic regions considered, the particle multiplicities are higher than predicted by the Monte Carlo models. The central charged-particle multiplicity per event and unit of pseudorapidity, for tracks with pT >100 MeV, is measured to be 3.483 +- 0.009 (stat) +- 0.106 (syst) at sqrt(s) = 0.9 TeV and 5.630 +- 0.003 (stat) +- 0.169 (syst) at sqrt(s) = 7 TeV.

2 data tables match query

The average charged-particle muliplicity per unit of rapidity for ETARAP=0 as a function of the centre-of-mass energy.

The average charged-particle muliplicity per unit of rapidity in the pseudorapidity region -2.5 to 2.5 for events with 2 or more charged particles as a function of the centre-of-mass energy.


Measurement of underlying event characteristics using charged particles in pp collisions at $\sqrt{s} = 900 GeV$ and 7 TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
Phys.Rev.D 83 (2011) 112001, 2011.
Inspire Record 879407 DOI 10.17182/hepdata.57151

Measurements of charged particle distributions, sensitive to the underlying event, have been performed with the ATLAS detector at the LHC. The measurements are based on data collected using a minimum-bias trigger to select proton-proton collisions at center-of-mass energies of 900 GeV and 7 TeV. The 'underlying event' is defined as those aspects of a hadronic interaction attributed not to the hard scattering process, but rather to the accompanying interactions of the rest of the proton. Three regions are defined in azimuthal angle with respect to the highest-pt charged particle in the event, such that the region transverse to the dominant momentum-flow is most sensitive to the underlying event. In each of these regions, distributions of the charged particle multiplicity, pt density, and average pt are measured. The data show a higher underlying event activity than that predicted by Monte Carlo models tuned to pre-LHC data.

22 data tables match query

Particle Number Density versus Lead Particle PT at centre-of-mass energy 900 GeV.

Particle Number Density versus Lead Particle PT at centre-of-mass energy 7000 GeV.

Particle PT Density versus Lead Particle PT at centre-of-mass energy 900 GeV.

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Study of Jet Shapes in Inclusive Jet Production in pp Collisions at sqrt(s) = 7 TeV using the ATLAS Detector

The ATLAS collaboration Aad, G. ; Abbott, B. ; Abdallah, J. ; et al.
Phys.Rev.D 83 (2011) 052003, 2011.
Inspire Record 882984 DOI 10.17182/hepdata.63511

Jet shapes have been measured in inclusive jet production in proton-proton collisions at sqrt(s) = 7 TeV using 3 pb^{-1} of data recorded by the ATLAS experiment at the LHC. Jets are reconstructed using the anti-kt algorithm with transverse momentum 30 GeV < pT < 600 GeV and rapidity in the region |y| < 2.8. The data are corrected for detector effects and compared to several leading-order QCD matrix elements plus parton shower Monte Carlo predictions, including different sets of parameters tuned to model fragmentation processes and underlying event contributions in the final state. The measured jets become narrower with increasing jet transverse momentum and the jet shapes present a moderate jet rapidity dependence. Within QCD, the data test a variety of perturbative and non-perturbative effects. In particular, the data show sensitivity to the details of the parton shower, fragmentation, and underlying event models in the Monte Carlo generators. For an appropriate choice of the parameters used in these models, the data are well described.

1 data table match query

Measured Differential Jet Shape RHO as a function of r for jet transverse momentum from 60 to 80 GeV and absolute values of the jet rapidity from 0 to 0.3. This is additional data, not in the paper.