Engineering Papers⌕ Search

Engineering topics

Saggio, A.

Publications and source records attributed to Saggio, A..

9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at $\sqrt{s}$ = 13 TeV

A search for new top quark interactions is performed within the framework of an effective field theory using the associated production of either one or two top quarks with a Z boson in multilepton final states. The data sample corresponds to an integrated luminosity of 138 fb -1 of proton-proton collisions at √s = 13 TeV collected by the CMS experiment at the LHC. Five dimension-six operators modifying the electroweak interactions of the top quark are considered. Novel machine-learning techniques are used to enhance the sensitivity to effects arising from these operators. Distributions used for the signal extraction are parameterized in terms of Wilson coefficients describing the interaction strengths of the operators. All five Wilson coefficients are simultaneously fit to data and 95% confidence level intervals are computed. All results are consistent with the SM expectations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Measurement of the azimuthal anisotropy of Υ(1S) and Υ(2S) mesons in PbPb collisions at $\sqrt{s_{NN}}$ = 5.02TeV

The second-order Fourier coefficients ( v 2 ) characterizing the azimuthal distributions of Υ(1S) and Υ(2S) mesons produced in PbPb collisions at s NN = 5.02 TeV are studied. The Υ mesons are reconstructed in their dimuon decay channel, as measured by the CMS detector. The collected data set corresponds to an integrated luminosity of 1.7 nb - 1 . The scalar product method is used to extract the v 2 coefficients of the azimuthal distributions. Results are reported for the rapidity range | y | < 2.4 , in the transverse momentum interval 0 < p T < 50 GeV / c , and in three centrality ranges of 10–30%, 30–50% and 50–90%. In contrast to the J / ψ mesons, the measured v 2 values for the Image 5 mesons are found to be consistent with zero.

5.02 TeV↗
DOE OSTI2021

Measurement of prompt ${\mathrm{D^0}}$ and ${\mathrm{\overline{D}}{}^0}$ meson azimuthal anisotropy and search for strong electric fields in PbPb collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV

The strong Coulomb field created in ultrarelativistic heavy ion collisions is expected to produce a rapidity-dependent difference ( Δv 2 ) in the second Fourier coefficient of the azimuthal distribution (elliptic flow, v 2 ) between D 0 ( $\bar{u}c$ ) and ${\mathrm{\overline{D}}{}^0}$ ( $u\bar{c}$ ) mesons. Motivated by the search for evidence of this field, the CMS detector at the LHC is used to perform the first measurement of Δv 2 . The rapidity-averaged value is found to be &lang;Δv2&rang;=0.001±0.001(stat)±0.003(syst) in PbPb collisions at $\sqrt{s_{NN}}$=5.02 TeV . In addition, the influence of the collision geometry is explored by measuring the D 0 and ${\mathrm{\overline{D}}{}^0}$ mesons v 2 and triangular flow coefficient ( v 3 ) as functions of rapidity, transverse momentum ( p T ), and event centrality (a measure of the overlap of the two Pb nuclei). A clear centrality dependence of prompt D 0 meson v 2 values is observed, while the v 3 is largely independent of centrality. These trends are consistent with expectations of flow driven by the initial-state geometry.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Measurement of differential t t ¯ production cross sections using top quarks at large transverse momenta in p p collisions at s = 13 TeV

A measurement is reported of differential top quark pair (${t\bar{t}}$) production cross sections, where top quarks are produced at large transverse momenta. The data collected with the CMS detector at the LHC are from pp collisions at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The measurement uses events where at least one top quark decays as t$ \to $Wb $ \to q\bar{q}'b$ and is reconstructed as a large-radius jet with transverse momentum in excess of 400 GeV. The second top quark is required to decay either in a similar way, or leptonically, as inferred from a reconstructed electron or muon, a bottom quark jet, and a missing transverse momentum due to the undetected neutrino. The cross section is extracted as a function of kinematic variables of individual top quarks or of the ${t\bar{t}}$ system. The results are presented at the particle level, within a region of phase space close to that of the experimental acceptance, and at the parton level, and are compared to various theoretical models. In both decay channels the observed absolute cross sections are significantly lower than the predictions from theory, while the normalized differential measurements are well described.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

The CMS Phase-1 Pixel Detector Upgrade

The CMS detector at the CERN LHC features a silicon pixel detector as its innermost subdetector. The original CMS pixel detector has been replaced with an upgraded pixel system (CMS Phase-1 pixel detector) in the extended year-end technical stop of the LHC in 2016/2017. The upgraded CMS pixel detector is designed to cope with the higher instantaneous luminosities that have been achieved by the LHC after the upgrades to the accelerator during the first long shutdown in 2013–2014. Compared to the original pixel detector, the upgraded detector has a better tracking performance and lower mass with four barrel layers and three endcap disks on each side to provide hit coverage up to an absolute value of pseudorapidity of 2.5. This paper describes the design and construction of the CMS Phase-1 pixel detector as well as its performance from commissioning to early operation in collision data-taking.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗