Dijet production in photon-photon collisions at S**(1/2)(ee) = 161-GeV and 172-GeV

The OPAL collaboration Abbiendi, G. ; Ackerstaff, K. ; Alexander, G. ; et al.
Eur.Phys.J.C 10 (1999) 547-561, 1999.
Inspire Record 474009 DOI 10.17182/hepdata.49386

Di-jet production is studied in collisions of quasi-real photons radiated by the LEP beams at e+e- centre-of-mass energies 161 and 172 GeV. The jets are reconstructed using a cone jet finding algorithm. The angular distributions of direct and double-resolved processes are measured and compared to the predictions of leading order and next-to-leading order perturbative QCD. The jet energy profiles are also studied. The inclusive two-jet cross-section is measured as a function of transverse energy and rapidity and compared to next-to-leading order perturbative QCD calculations. The inclusive two-jet cross-section as a function of rapidity is compared to the prediction of the leading order Monte Carlo generators PYTHIA and PHOJET. The Monte Carlo predictions are calculated with different parametrisations of the parton distributions of the photon. The influence of the `underlying event' has been studied to reduce the model dependence of the predicted jet cross-sections from the Monte Carlo generators.

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Single electrons from heavy flavor decays in p + p collisions at s**(1/2) = 200-GeV.

The PHENIX collaboration ~Adler, S.S. ; ~Afanasiev, S. ; ~Aidala, C. ; et al.
Phys.Rev.Lett. 96 (2006) 032001, 2006.
Inspire Record 689883 DOI 10.17182/hepdata.139174

The invariant differential cross section for inclusive electron production in $p + p$ collisions at $\sqrt{s} = 200$~GeV has been measured by the PHENIX experiment at the Relativistic Heavy Ion Collider over the transverse momentum range $0.4 \le p_T \le 5.0$~GeV/$c$ in the central rapidity region ($|\eta| \le 0.35$). The contribution to the inclusive electron spectrum from semileptonic decays of hadrons carrying heavy flavor, {\it i.e.} charm quarks or, at high $p_T$, bottom quarks, is determined via three independent methods. The resulting electron spectrum from heavy flavor decays is compared to recent leading and next-to-leading order perturbative QCD calculations. The total cross section of charm quark-antiquark pair production is determined to be $\sigma_{c\bar{c}} = 0.92 \pm 0.15 {\rm (stat.)} \pm 0.54 {\rm (sys.)}$~mb.

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Cross-section for forward J / psi production in p anti-p collisions at S = 1.8-TeV

The CDF collaboration Acosta, D. ; Affolder, T. ; Akimoto, H. ; et al.
Phys.Rev.D 66 (2002) 092001, 2002.
Inspire Record 603674 DOI 10.17182/hepdata.22217

The inclusive cross section for J/ψ production times the branching ratio B(J/ψ→μ+μ−) has been measured in the forward pseudorapidity region: B×dσ[p¯+p→J/ψ(pT>10GeV/c,2.1<|η|<2.6)+X]/dη=192±9(stat)±29(syst)pb. The results are based on 74.1±5.2pb−1 of data collected by the CDF Collaboration at the Fermilab Tevatron Collider. The measurements extend earlier measurements of the D0 Collaboration to higher pTJ/ψ. In the kinematic range where the experiments partially overlap, these data are in good agreement with previous measurements.

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The $\Lambda\Lambda$ Correlation Function in Au+Au collisions at $\sqrt{s_{NN}}=$ 200 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 114 (2015) 022301, 2015.
Inspire Record 1311513 DOI 10.17182/hepdata.73492

We present $\Lambda\Lambda$ correlation measurements in heavy-ion collisions for Au+Au collisions at $\sqrt{s_{NN}}= 200$ GeV using the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). The Lednick\'{y}-Lyuboshitz analytical model has been used to fit the data to obtain a source size, a scattering length and an effective range. Implications of the measurement of the $\Lambda\Lambda$ correlation function and interaction parameters for di-hyperon searches are discussed.

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Precise Measurement of the Left-Right Cross Section Asymmetry in $Z$ Boson Production by $\ee$ Collisions

The SLD collaboration Abe, K. ; Abt, I. ; Ash, W.W. ; et al.
Phys.Rev.Lett. 73 (1994) 25-29, 1994.
Inspire Record 373007 DOI 10.17182/hepdata.19681

We present a precise measurement of the left-right cross section asymmetry ($A_{LR}$) for $Z$ boson production by $\ee$ collisions. The measurement was performed at a center-of-mass energy of 91.26 GeV with the SLD detector at the SLAC Linear Collider (SLC). The luminosity-weighted average polarization of the SLC electron beam was (63.0$\pm$1.1)%. Using a sample of 49,392 $\z0$ decays, we measure $A_{LR}$ to be 0.1628$\pm$0.0071(stat.)$\pm$0.0028(syst.) which determines the effective weak mixing angle to be $\swein=0.2292\pm0.0009({\rm stat.})\pm0.0004({\rm syst.})$.}

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Measurements of transverse energy distributions in Au + Au collisions at s(NN)**(1/2) = 200-GeV.

The STAR collaboration Adams, J. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 70 (2004) 054907, 2004.
Inspire Record 653797 DOI 10.17182/hepdata.98621

Transverse energy ($E_T$) distributions have been measured for Au+Au collisions at $\sqrt{s_{NN}}= 200$ GeV by the STAR collaboration at RHIC. $E_T$ is constructed from its hadronic and electromagnetic components, which have been measured separately. $E_T$ production for the most central collisions is well described by several theoretical models whose common feature is large energy density achieved early in the fireball evolution. The magnitude and centrality dependence of $E_T$ per charged particle agrees well with measurements at lower collision energy, indicating that the growth in $E_T$ for larger collision energy results from the growth in particle production. The electromagnetic fraction of the total $E_T$ is consistent with a final state dominated by mesons and independent of centrality.

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Elliptic and hexadecapole flow of charged hadrons in Au+Au collisions at sqrt(s_NN) = 200 GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.Lett. 105 (2010) 062301, 2010.
Inspire Record 850211 DOI 10.17182/hepdata.143006

Differential measurements of the elliptic (v_2) and hexadecapole (v_4) Fourier flow coefficients are reported for charged hadrons as a function of transverse momentum (p_T) and collision centrality or the number of participant nucleons (N_part) for Au+Au collisions at sqrt(s_NN)=200 GeV. The v_{2,4} measurements at pseudorapidity |\eta|<=0.35 obtained with four separate reaction plane detectors positioned in the range 1.0<|\eta|<3.9 show good agreement, indicating the absence of significant \eta-dependent nonflow perturbations. Sizable values for v_4(p_T) are observed with a ratio v_4(p_T,N_part)/v_2^2(p_T,N_part)~0.8 for 50<N_part<200, which is compatible with the combined effects of a finite viscosity and initial eccentricity fluctuations. For N_part>200 this ratio increases up to 1.7 in the most central collisions.

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Limits on the production of direct photons in 200-A/GeV S-32 + Au collisions

The WA80 collaboration Albrecht, R. ; Antonenko, V. ; Awes, T.C. ; et al.
Phys.Rev.Lett. 76 (1996) 3506-3509, 1996.
Inspire Record 404322 DOI 10.17182/hepdata.19585

A search for the production of direct photons in S+Au collisions at 200AGeV has been carried out in the CERN-WA80 experiment. For central collisions the measured photon excess at each pT, averaged over the range 0.5≤pT≤2.5GeV/c, corresponded to 5.0% of the total inclusive photon yield with a statistical error of σstat=0.8% and a systematic error of σsyst=5.8%. Upper limits on the invariant yield for direct photon production at the 90% C.L. are presented. Possible implications for the dynamics of high-energy heavy-ion collisions are discussed.

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Measurement of the angle between jet axes in pp collisions at $\sqrt{s} = 5.02$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 07 (2023) 201, 2023.
Inspire Record 2182727 DOI 10.17182/hepdata.138866

This article reports measurements of the angle between differently defined jet axes in pp collisions at $\sqrt{s} = 5.02$ TeV carried out by the ALICE Collaboration. Charged particles at midrapidity are clustered into jets with resolution parameters $R=0.2$ and 0.4. The jet axis, before and after Soft Drop grooming, is compared to the jet axis from the Winner-Takes-All (WTA) recombination scheme. The angle between these axes, $\Delta R_{\mathrm{axis}}$, probes a wide phase space of the jet formation and evolution, ranging from the initial high-momentum-transfer scattering to the hadronization process. The $\Delta R_{\mathrm{axis}}$ observable is presented for $20 < {p_{\mathrm{T}}^{\mathrm{ch\; jet}}}< 100$ GeV/$c$, and compared to predictions from the PYTHIA 8 and Herwig 7 event generators. The distributions can also be calculated analytically with a leading hadronization correction related to the non-perturbative component of the Collins$-$Soper$-$Sterman (CSS) evolution kernel. Comparisons to analytical predictions at next-to-leading-logarithmic accuracy with leading hadronization correction implemented from experimental extractions of the CSS kernel in Drell$-$Yan measurements are presented. The analytical predictions describe the measured data within 20% in the perturbative regime, with surprising agreement in the non-perturbative regime as well. These results are compatible with the universality of the CSS kernel in the context of jet substructure.

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Underlying-event properties in pp and p$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV

The ALICE collaboration Acharya, S. ; Adamová, D. ; Adler, A. ; et al.
JHEP 06 (2023) 023, 2023.
Inspire Record 2071174 DOI 10.17182/hepdata.133032

We report about the properties of the underlying event measured with ALICE at the LHC in pp and p$-$Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV. The event activity, quantified by charged-particle number and summed-$p_{\rm T}$ densities, is measured as a function of the leading-particle transverse momentum ($p_{\rm T}^{\rm trig}$). These quantities are studied in three azimuthal-angle regions relative to the leading particle in the event: toward, away, and transverse. Results are presented for three different $p_{\rm T}$ thresholds (0.15, 0.5, and 1 GeV/$c$) at mid-pseudorapidity ($|\eta|<0.8$). The event activity in the transverse region, which is the most sensitive to the underlying event, exhibits similar behaviour in both pp and p$-$Pb collisions, namely, a steep increase with $p_{\rm T}^{\rm trig}$ for low $p_{\rm T}^{\rm trig}$, followed by a saturation at $p_{\rm T}^{\rm trig} \approx 5$ GeV/$c$. The results from pp collisions are compared with existing measurements at other centre-of-mass energies. The quantities in the toward and away regions are also analyzed after the subtraction of the contribution measured in the transverse region. The remaining jet-like particle densities are consistent in pp and p$-$Pb collisions for $p_{\rm T}^{\rm trig}>10$ GeV/$c$, whereas for lower $p_{\rm T}^{\rm trig}$ values the event activity is slightly higher in p$-$Pb than in pp collisions. The measurements are compared with predictions from the PYTHIA 8 and EPOS LHC Monte Carlo event generators.

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