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ATLAS Collaboration(Aad, G. et al), Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Cardillo, F., et al. (2022). Measurement of the energy asymmetry in t(t)over-barj production at 13 TeV with the ATLAS experiment and interpretation in the SMEFT framework. Eur. Phys. J. C, 82(4), 374–36pp.
Abstract: A measurement of the energy asymmetry in jet-associated top-quark pair production is presented using 139 fb(-1) of data collected by the ATLAS detector at the Large Hadron Collider during pp collisions at root s = 13 TeV. The observable measures the different probability of top and antitop quarks to have the higher energy as a function of the jet scattering angle with respect to the beam axis. The energy asymmetry is measured in the semileptonic t (t) over bar decay channel, and the hadronically decaying top quark must have transverse momentum above 350 GeV. The results are corrected for detector effects to particle level in three bins of the scattering angle of the associated jet. The measurement agrees with the SM prediction at next-to-leading-order accuracy in quantum chromodynamics in all three bins. In the bin with the largest expected asymmetry, where the jet is emitted perpendicular to the beam, the energy asymmetry is measured to be -0.043 +/- 0.020, in agreement with the SM prediction of -0.037 +/- 0.003. Interpreting this result in the framework of the Standard Model effective field theory (SMEFT), it is shown that the energy asymmetry is sensitive to the top-quark chirality in four-quark operators and is therefore a valuable new observable in global SMEFT fits.
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Capozzi, F., & Petcov, S. T. (2022). Neutrino tomography of the Earth with ORCA detector. Eur. Phys. J. C, 82(5), 461–23pp.
Abstract: Using PREM as a reference model for the Earth density distribution we investigate the sensitivity of ORCA detector to deviations of the Earth (i) outer core (OC) density, (ii) inner core (IC) density, (iii) total core density, and (iv) mantle density, from their respective PREM densities. The analysis is performed by studying the effects of the Earth matter on the oscillations of atmospheric nu(mu), nu(e), (nu) over bar (mu) and (nu) over bar (e). We present results which illustrate the dependence of the ORCA sensitivity to the OC, IC, core and mantle densities on the type of systematic uncertainties used in the analysis, on the value of the atmospheric neutrino mixing angle theta(23), on whether the Earth mass constraint is implemented or not, and on the way it is implemented, and on the type – with normal ordering (NO) or inverted ordering (IO) – of the light neutrino mass spectrum. We show, in particular, that in the “most favorable” NO case of implemented Earth mass constraint, “minimal” systematic errors and sin(2) theta(23) = 0.58, ORCA can determine, e.g., the OC (mantle) density at 3 sigma C.L. after 10 years of operation with an uncertainty of (- 18%)/+ 15% (of (- 6%)/+ 8%). In the “most disfavorable” NO case of “conservative” systematic errors and sin(2) theta(23) = 0.42, the uncertainty on OC (mantle) density reads (- 43%)/+ 39% ((- 17%/+ 20%), while for for sin(2) theta(23) = 0.50 and 0.58 it is noticeably smaller: (- 37)%/+ 30% and (- 30%)/+ 24% ((- 13%)/+ 16% and (- 11%/+ 14%)). We find also that the sensitivity of ORCA to the OC, core and mantle densities is significantly worse for IO neutrino mass spectrum.
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Camarda, S., Cieri, L., Ferrera, G., & Urtasun-Elizari, J. (2022). Higgs boson production at the LHC: fast and precise predictions in QCD at higher orders. Eur. Phys. J. C, 82(5), 492–8pp.
Abstract: We present a new numerical program, HTurbo, which provides fast and numerically precise predictions for Higgs boson production cross sections. The present version of the code implements the perturbative QCD expansion up to the next-to-next-to-leading order also combined with the resummation of the large logarithmic corrections at small transverse momenta up to next-to-next-to-leading logarithmic accuracy and it includes the Higgs boson production through gluon fusion and decay in two photons with the full dependence on the final-state kinematics. Arbitrary kinematical cuts can be applied to the final states in order to obtain fiducial cross sections and associated kinematical distributions. We present a benchmark comparison with the predictions obtained with the numerical programs HRes and HNNLO programs for which HTurbo represents an improved reimplementation.
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ATLAS Collaboration(Aad, G. et al), Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Cardillo, F., et al. (2022). Determination of the parton distribution functions of the proton using diverse ATLAS data from pp collisions at root s=7, 8 and 13 TeV. Eur. Phys. J. C, 82(5), 438–70pp.
Abstract: This paper presents an analysis at next-to-next-to-leading order in the theory of quantum chromodynamics for the determination of a new set of proton parton distribution functions using diverse measurements in pp collisions at root s = 7, 8 and 13 TeV, performed by the ATLAS experiment at the Large Hadron Collider, together with deep inelastic scattering data from ep collisions at the HERA collider. The ATLAS data sets considered are differential cross-section measurements of inclusive W-+/- and Z/gamma* boson production, W-+/- and Z boson production in association with jets, t (t) over bar production, inclusive jet production and direct photon production. In the analysis, particular attention is paid to the correlation of systematic uncertainties within and between the various ATLAS data sets and to the impact of model, theoretical and parameterisation uncertainties. The resulting set of parton distribution functions is called ATLASpdf21.
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Bandyopadhyay, P., Jangid, S., & Karan, A. (2022). Constraining scalar doublet and triplet leptoquarks with vacuum stability and perturbativity. Eur. Phys. J. C, 82(6), 516–44pp.
Abstract: We investigate the constraints on the leptoquark Yukawa couplings and the Higgs-leptoquark quartic couplings for scalar doublet leptoquark (R) over tilde (2), scalar triplet leptoquark S-3 and their combination with both three generations and one generation with respect to perturbative unitarity and vacuum stability. The perturbative unitarity of all the dimensionless couplings is studied via one- and two-loop beta functions. New SU(2)(L) multiplets in terms of these leptoquarks are introduced to fabricate Landau poles at the two-loop level in the gauge coupling g(2) at 10(19.7) GeV and 10(14.4) GeV, respectively, for the S-3 and (R) over tilde (2) + S-3 models with three generations. However, such Landau poles cease to exist for (R) over tilde (2) and any of these extensions with both one and two generations up to Planck scale. The Higgs-leptoquark quartic couplings acquire severe constraints to protect Planck scale perturbativity, whereas leptoquark Yukawa couplings acquire some upper bound in order to respect Planck scale stability of Higgs vacuum. The Higgs quartic coupling at the two-loop level constrains the leptoquark Yukawa couplings for (R) over tilde (2), S-3, (R) over tilde (2) + S-3 with values less than or similar to 1.30, 3.90, 1.00 with three generations. In the effective potential approach, the presence of any of these leptoquarks with any number of generations pushes the metastable vacuum of the Standard Model to the stable region.
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