Inspire | HepData | Analysis reference | submitted to EPJC | arXiv:1707.02562
Measurements of transverse energy-energy correlations and their associated asymmetries in multi-jet events using the ATLAS detector at the LHC are presented. The data used correspond to $\sqrt{s} = 8$ TeV proton-proton collisions with an integrated luminosity of 20.2 fb$^{-1}$. The results are presented in bins of the scalar sum of the transverse momenta of the two leading jets, unfolded to the particle level and compared to the predictions from Monte Carlo simulations. A comparison with next-to-leading-order perturbative QCD is also performed, showing excellent agreement within the uncertainties. From this comparison, the value of the strong coupling constant is extracted for different energy regimes, thus testing the running of $\alpha_\text{s}(\mu)$ predicted in QCD up to scales over 1 TeV. A global fit to the transverse energy-energy correlation distributions yields $\alpha_\text{s}(m_Z) = 0.1162\pm 0.0011\text{(exp.)}^{+0.0084}_{-0.0070}\text{(theo.)}$, while a global fit to the asymmetry distributions yields a value of $\alpha_\text{s}(m_Z) = 0.1196\pm 0.0013\text{(exp.)}^{+0.0075}_{-0.0045}\text{(theo.)}$.
Inspire | HepData | Analysis reference | JHEP 09 (2017) 020 | arXiv:1706.03192
Inclusive jet production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=8$ TeV recorded by the ATLAS experiment at the Large Hadron Collider at CERN. The total integrated luminosity of the analysed data set amounts to 20.2 fb$^{-1}$. Double-differential cross-sections are measured for jets defined by the anti-$k_\text{t}$ jet clustering algorithm with radius parameters of $R=0.4$ and $R=0.6$ and are presented as a function of the jet transverse momentum, in the range between 70 GeV and 2.5 TeV and in six bins of the absolute jet rapidity, between 0 and 3.0. The measured cross-sections are compared to predictions of quantum chromodynamics, calculated at next-to-leading order in perturbation theory, and corrected for non-perturbative and electroweak effects. The level of agreement with predictions, using a selection of different parton distribution functions for the proton, is quantified. Tensions between the data and the theory predictions are observed.
Inspire | HepData | Analysis reference | Eur.Phys.J. C77 (2017) no.11, 746 | arXiv:1705.02628
A measurement is presented of the triple-differential dijet cross section at a centre-of-mass energy of 8 TeV using 19.7 fb$^-1$ of data collected with the CMS detector in proton-proton collisions at the LHC. The cross section is measured as a function of the average transverse momentum, half the rapidity separation, and the boost of the two leading jets in the event. The cross section is corrected for detector effects and compared to calculations in perturbative quantum chromodynamics at next-to-leading order accuracy, complemented with electroweak and nonperturbative corrections. New constraints on parton distribution functions are obtained and the inferred value of the strong coupling constant is $\alpha_s(M_{Z})$ = 0.1199 $\pm$ 0.0015 (exp)$^{+0.0031}_{-0.0020}$ (theo), where M$_{Z}$ is the mass of the Z boson.
Inspire | HepData | Analysis reference | DOI:10.1007/JHEP03(2017)156 | arXiv:1609.05331 | CMS-SMP-14-001
A measurement of the double-differential inclusive jet cross section as a function of the jet transverse momentum $\pt$ and the absolute jet rapidity $\abs{y}$ is presented. Data from LHC proton-proton collisions at $\sqrt{s}=8\text{TeV}$, corresponding to an integrated luminosity of 19.7 fb^{-1}, have been collected with the CMS detector. Jets are reconstructed using the anti-$\kt$ clustering algorithm with a size parameter of 0.7 in a phase space region covering jet $\pt$ from $74\text{GeV}$ up to $2.5\text{TeV}$ and jet absolute rapidity up to $\abs{y}=3.0$. The low-$\pt$ jet range between 21 and $74\text{GeV}$ is also studied up to $\abs{y}=4.7$, using a dedicated data sample corresponding to an integrated luminosity of 5.6\pbinv. The measured jet cross section is corrected for detector effects and compared with the predictions from perturbative QCD at next-to-leading order (NLO) using various sets of parton distribution functions (PDF). Cross section ratios to the corresponding measurements performed at 2.76 and $7\text{TeV}$ are presented. From the measured double-differential jet cross section, the value of the strong coupling constant evaluated at the $Z$ mass is $\alpha_\mathrm{S}(M_{Z}) = 0.1164^{+0.0060}_{-0.0043}$, where the errors include the PDF, scale, nonperturbative effects and experimental uncertainties, using the CT10 NLO PDFs. Improved constraints on PDFs based on the inclusive jet cross section measurement are presented.
Inspire | HepData | Analysis reference | arXiv:1602.04384 | CERN-PH-EP-2016-013
A measurement of the decorrelation of azimuthal angles between the two jets with the largest transverse momenta is presented for seven regions of leading jet transverse momentum up to 2.2 TeV. The analysis is based on the proton-proton collision data collected with the CMS experiment at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7/fb. The dijet azimuthal decorrelation is caused by the radiation of additional jets and probes the dynamics of multijet production. The results are compared to fixed-order predictions of perturbative quantum chromodynamics (QCD), and to simulations using Monte Carlo event generators that include parton showers, hadronization, and multiparton interactions. Event generators with only two outgoing high transverse momentum partons fail to describe the measurement, even when supplemented with next-to-leading-order QCD corrections and parton showers. Much better agreement is achieved when at least three outgoing partons are complemented through either next-to-leading-order predictions or parton showers. This observation emphasizes the need to improve predictions for multijet production.
Inspire | HepData | Analysis reference
A search is presented for quark contact interactions and extra spatial dimensions in proton-proton collisions at sqrt(s) = 8 TeV using dijet angular distributions. The search is based on a data set corresponding to an integrated luminosity of 19.7 fb-1 collected by the CMS detector at the CERN LHC. Dijet angular distributions are found to be in agreement with the perturbative QCD predictions that include electroweak corrections. Limits on the contact interaction scale from a variety of models at next-to-leading order in QCD corrections are obtained. A benchmark model in which only left-handed quarks participate is excluded up to a scale of 9.0 (11.7) TeV for destructive (constructive) interference at 95% confidence level. Lower limits between 6.0 and 8.4 TeV on the scale of virtual graviton exchange are extracted for the Arkani-Hamed--Dimopoulos--Dvali model of extra spatial dimensions.
Jets with $p_\perp>20$ GeV are constructed with an anti-$k_\perp$ jet finder with $R=0.4$ and projected onto many different observables.
Monte Carlo validation observables for jet production