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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Probing New Physics with Tau Leptons using the CMS Detector

The Standard Model (SM) of particle physics is a thoroughly well-tested theory of all electroweak scale phenomena to date—the most recent test being the discovery of the long-predicted Higgs boson. However, there is much evidence to suggest that it is incomplete. On the formal side, the mass of the Higgs particle itself is perplexingly small, while the largest theoretical energy scale of the SM is 17 orders of magnitude larger, a puzzle known as the hierarchy problem. On the experimental side, among other things, the SM lacks a candidate for dark matter, which is now known to play an indispensable role in astrophysical large scale structure formation. Many theories that address the fundamental puzzles of the SM predict the existence of multiple Higgs bosons, including a very light boson that couples preferentially to third-generation fermions. Observation of this new light boson, either directly produced or in the decay of the recently discovered SM Higgs, would provide an unmistakable sign of new dynamics in nature. The research supported by this award used data collected by the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) to explore boosted di-tau signatures of a new light boson as a tool in the quest to understand the shortcomings of the SM. With a proton-proton collision energy of 13 trillion electron-volts (TeV) and peak instantaneous proton luminosity of over 10^34 collisions per square centimeter per second (cm –2 s –1 ), the LHC is the only facility in the world that could enable this line of research. The research sought to address the hierarchy problem and other shortcomings of the SM through a mixture of LHC data analysis, maintenance of the CMS detector to ensure high quality data, and contributions to the Phase 2 upgrade detector for the upcoming High Luminosity phase of the LHC (HL-LHC).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

New Jet Tagging Techniques in Vector Boson Scattering (VBS) WV Analysis in the Semi-Leptonic Channel with the CMS Experiment

The first evidence for the electroweak vector boson scattering in the lνqq¯ decay channel of two weak vector bosons WV (V=W, Z), produced in association with two parton jets, was reported in 2021 by the CMS experiment in proton-proton collisions at √s = 13 TeV, collected during 2016-2018, with an integrated luminosity of 138 f b −1 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Limits on Leptonic TeV Emission from the Cygnus Cocoon with Swift-XRT

$\gamma$-ray observations of the Cygnus Cocoon, an extended source surrounding the Cygnus X star-forming region, suggest the presence of a cosmic ray accelerator reaching energies up to a few PeV. The very-high-energy (VHE; 0.1-100~TeV) $\gamma$-ray emission may be explained by the interaction of cosmic-ray hadrons with matter inside the Cocoon, but an origin of inverse Compton radiation by relativistic electrons cannot be ruled out. Inverse Compton $\gamma$-rays at VHE are accompanied by synchrotron radiation peaked in X-rays. Hence, X-ray observations may probe the electron population and magnetic field of the source. We observed eleven fields in or near the Cygnus Cocoon with the Neil Gehrels Swift Observatory's X-Ray Telescope (Swift-XRT) totaling 110 ksec. We fit the fields to a Galactic and extra-galactic background model and performed a log-likelihood ratio test for an additional diffuse component. We found no significant additional emission and established upper limits in each field. By assuming that the X-ray intensity traces the TeV intensity and follows an dN/dE ∝ E -2.5 spectrum, we obtained a 90% upper limit of F X < 8.7 x 10 -11 erg cm -2 s -1 or 5.2 x10 -11 erg cm -2 s -1 on the X-ray flux of the entire Cygnus Cocoon between 2 and 10 keV depending on the choice of hydrogen column density model. This suggests that no more than one quarter of the $\gamma$-ray flux at 1 TeV is produced by inverse Compton scattering, when assuming an equipartition magnetic field of ~20 μG.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1975

Measurements of selected psi /3684/ branching ratios from a study of secondary lepton pairs

The measurements considered were made at the electron-positron storage ring at the Stanford Linear Accelerator Center. The apparatus used consists of two identical spectrometers mounted in a collinear configuration about the beam-interaction region. The energies of secondary electrons or positrons are measured with good resolution in large NaI(Tl) total-absorption detectors. Data accumulated without gamma-ray converters were examined for electron-positron pairs. The data taken with gamma-ray converters in place and at center-of-mass energies within 1 MeV of the resonance energy were scanned for evidence of either charged particles or converted gamma rays accompanying the detected muon pairs.

Hilger, E.↗
NASA NTRS1985

Charge 4/3 leptons in cosmic rays

A cosmic ray counter telescope has been operated at zenith angles of 0, 40, 44, and 60 degs in order to look for charge 4/3 particles. A few million clean single cosmic rays of each zenith angle are analyzed.

Wada, T.↗