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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 1,351 records · Page 75
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DOE OSTI2015

Summary of the ATLAS experiment’s sensitivity to supersymmetry after LHC Run 1 -- interpreted in the phenomenological MSSM

A summary of the constraints from the ATLAS experiment on R -parity-conserving supersymmetry is presented. Results from 22 separate ATLAS searches are considered, each based on analysis of up to 20.3 fb –1 of proton-proton collision data at centre-of-mass energies of √s =7 and 8 TeV at the Large Hadron Collider. The results are interpreted in the context of the 19-parameter phenomenological minimal supersymmetric standard model, in which the lightest supersymmetric particle is a neutralino, taking into account constraints from previous precision electroweak and flavour measurements as well as from dark matter related measurements. The results are presented in terms of constraints on supersymmetric particle masses and are compared to limits from simplified models. The impact of ATLAS searches on parameters such as the dark matter relic density, the couplings of the observed Higgs boson, and the degree of electroweak fine-tuning is also shown. As a result, spectra for surviving supersymmetry model points with low fine-tunings are presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

{ital N}* Structure and Strong QCD

In attempting to match QCD with Nature, it is necessary to confront the many complexities of strong, nonlinear dynamics in relativistic quantum field theory, e.g. the loss of particle number conservation, the frame and scale dependence of the explanations and interpretations of observable processes, and the evolving character of the relevant degrees-of-freedom. The peculiarities of QCD ensure that it is also the only known fundamental theory with the capacity to sustain massless elementary degrees-of-freedom, gluons and quarks; and yet gluons and quarks are predicted to acquire mass dynamically so that the only massless systems in QCD are its composite Nambu-Goldstone bosons. All other everyday bound states possess nuclear-size masses, far in excess of anything that can directly be tied to the Higgs boson. These observations highlight fundamental questions within the Standard Model: what is the source of the mass for the vast bulk of visible matter in the Universe, how is its appearance connected with confinement; how is this mass distributed within hadrons and does the distribution differ from one hadron to another? This contribution sketches insights drawn using modern methods for the continuum bound-state problem in QCD, and how they have been informed by empirical information on the hadron spectrum and nucleon-to-resonance transition form factors.

Roberts, Craig D.↗
DOE OSTI2024

Warm inflation with a heavy QCD axion

We propose the first model of warm inflation in which the particle production emerges directly from coupling the inflaton to Standard Model particles. Warm inflation, an early epoch of sustained accelerated expansion at finite temperature, is a compelling alternative to cold inflation, with distinct predictions for inflationary observables such as the amplitude of fluctuations, the spectral tilt, the tensor-to-scalar ratio, and non-gaussianities. In our model a heavy QCD axion acts as the warm inflaton whose coupling to Standard Model gluons sources the thermal bath during warm inflation. Axion-like couplings to non-Abelian gauge bosons have been considered before as a successful microphysical theory with emerging thermal friction that can maintain finite temperature during inflation via sphaleron heating. However, the presence of light fermions charged under the non-Abelian group suppresses particle production, hindering a realization of warm inflation by coupling to QCD. We point out that the Standard Model quarks can be heavy during warm inflation if the Higgs field resides in a high-energy second minimum which restores efficient sphaleron heating. A subsequent large reheating temperature is required to allow the Higgs field to relax to its electroweak minimum. Exploring a scenario in which hybrid warm inflation provides the large reheating temperature, we show that future collider and beam dump experiments have discovery potential for a heavy QCD axion taking the role of the warm inflaton.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Probing atomic Higgs-like forces at the precision frontier

We propose here a novel approach to probe new fundamental interactions using isotope shift spectroscopy in atomic clock transitions. As a concrete toy example we focus on the Higgs boson couplings to the building blocks of matter: the electron and the up and down quarks. We show that the attractive Higgs force between nuclei and their bound electrons, which is poorly constrained, might induce effects that are larger than the current experimental sensitivities. More generically, we discuss how new interactions between the electron and the neutrons, mediated via light new degrees of freedom, may lead to measurable nonlinearities in a King plot comparison between isotope shifts of two different transitions. Given state-of-the-art accuracy in frequency comparison, isotope shifts have the potential to be measured with sub-Hz accuracy, thus potentially enabling the improvement of current limits on new fundamental interactions. A candidate atomic system for this measurement requires two different clock transitions and four zero nuclear spin isotopes. We identify several systems that satisfy this requirement and also briefly discuss existing measurements. We consider the size of the effect related to the Higgs force and the requirements for it to produce an observable signal.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Search for the Dark Photon and the Dark Higgs Boson at Belle

The dark photon A ' and the dark Higgs boson h ' are hypothetical constituents featured in a number of recently proposed dark sector models. Assuming prompt decays of both dark particles, we search for their production in the so-called Higgstrahlung channel e + e - → A ' h ' , with h ' → A ' A ' . We investigate ten exclusive final states with A ' → e + e - , μ + μ - , or π + π - in the mass ranges 0.1 GeV / c 2 < m A ' < 3.5 GeV / c 2 and 0.2 GeV / c 2 < m h ' < 10.5 GeV / c 2 . We also investigate three inclusive final states 2 ( e + e - ) X , 2 ( μ + μ - ) X , and ( e + e - ) ( μ + μ - ) X , where X denotes a dark photon candidate detected via missing mass, in the mass ranges 1.1 GeV / c 2 < m A ' < 3.5 GeV / c 2 and 2.2 GeV / c 2 < m h ' < 10.5 GeV / c 2 . Using the entire 977 fb - 1 data set collected by Belle, we determine no significant signal. Here, we obtain individual and combined 90% credibility level upper limits on the branching fraction times the Born cross section, B × σ Born , on the Born cross section σ Born , and on the dark photon coupling to the dark Higgs boson times the kinetic mixing between the standard model photon and the dark photon, α D × ε 2 . These limits improve upon and cover wider mass ranges than previous experiments. The limits from the final states 3 ( π + π - ) and 2 ( e + e - ) X are the first placed by any experiment. For α D equal to 1 / 137 , m h ' < 8 GeV / c 2 , and m A ' < 1 GeV / c 2 , we exclude values of the mixing parameter ε above ~ 8×10 -4 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Excitations of static isolated fermions in the Higgs phase of gauge Higgs theory

A spectrum of localized excitations of isolated static fermions has been discovered in several different gauge Higgs theories. In lattice numerical simulations, we show that the charged elementary particles can have the spectrum of excitations in the Higgs phase of SU(3) gauge Higgs theory, q=2 Abelian Higgs theory, Landau-Ginzburg theory, and in chiral U(1) gauge Higgs theory. Possibly these excited states of the isolated fermions can be observed in ARPES studies of conventional superconductors. Also, we consider that similar kinds of excitations could exist in other gauge Higgs theories, such as the electroweak sector of the Standard Model.

Matsuyama, Kazue↗
DOE OSTI2022

Physics motivation and detector upgrades for the new era of the ATLAS experiment

The ATLAS experiment at CERN’s Large Hadron Collider (LHC) will be upgraded in two stages to prepare first for the Run~3 data-taking campaign, during which the integrated luminosity will roughly double, and then for the High-Luminosity LHC program with an ultimate integrated luminosity of up to 4 ab ^{{-1}} − 1 . These upgrades and high-statistics datasets will allow ATLAS to perform searches and precision measurements to constrain the Standard Model in yet-unexplored phase spaces and in the Higgs sector. This contribution summarizes the ATLAS detector upgrades and selected physics prospects for Run~3 and the HL-LHC.

Nielsen, Jason↗
DOE OSTI2018

Performance of b Jet Identification at $\sqrt{s}$ = 13 TeV with the ATLAS Detector at CERN [Slides]

The efficient identification of jets from bottom quarks (b-jets) is one of the most important techniques for many physics analyses at the Large Hadron Collider, including studies of the Higgs boson, the top quark, and searches beyond the Standard Model. The performance is characterized by b-tagging efficiency (probability to identify a b-jet as such) and the mistag rate (probability to mistakenly accept a non-b-jet).The mistag occurs as a result of finite detector resolution, presence of long-lived particles, and material interactions. As these effects can be different between the experimental data and Monte Carlo (MC) simulation, it is important to measure the b-tagging performance in data and derive the MC correction factors. I will describe various methods to measure the performance of b jet identification in pp collisions at √s = 13 TeV with the ATLAS detector and will report on Direct Tag method which is recently developed in the ATLAS collaboration for Light jet calibration.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Latin American Strategy for Research Infrastructures for High Energy, Cosmology, Astroparticle Physics LASF4RI for HECAP

The present document, the Latin American HECAP Physics Briefing Book, is the result of this ambitious grass roots effort. This report contains the work performed by the Preparatory Group to synthesize the main contributions and discussions for each of the topical working groups: Astronomy, Astrophysics and Astroparticle Physics; Cosmology; Dark Matter; Neutrinos; Electroweak and Strong Interactions, Higgs physics, Flavour and CP Physics and Beyond the Standard Model Physics; Instrumentation and Computing. This work aims at providing a landscape of existing expertise and capabilities. It will hopefully instruct some recommendations for further development of strategic research infrastructures relevant for future HECAP efforts in the region as well as for a continuous and successful involvement of Latin American HECAP researchers in the global arena.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Axion-like particle at the 10 GeV scale: Higgs decays to wide jets and photons

If axion-like particles (ALPs) exist, they may have renormalizable couplings only to the Higgs boson ($h^0$) or to fields beyond the Standard Model. An ALP $A_h$ lighter than about 60 GeV would allow the $h^0 \to A_h A_h$ decay, with a branching fraction determined by the explicit global symmetry breaking responsible for the main contributions to the $A_h$ mass ($M_A$). New heavy fields that carry color and electric charge, such as squarks, can mediate $A_h$ decays at one loop mostly into gluons, but also into photons. Exploring LHC sensitivity to $A_h$, we show that the $h^0 \to A_h A_h \to (gg)(γγ)$ channel leads to a diphoton resonance at $M_A$ whose production rate is consistent with a $3.5σ$ excess reported by a CMS search at $M_A \approx 13.6$ GeV. For $M_A$ of order 10 GeV, the $h^0 \to A_h A_h \to 4g$ cascade decay leads to two wide jets (each with 2-prong substructure) that form a resonance at 125 GeV.

Dobrescu, Bogdan A. [Fermilab] (ORCID:000000034291↗