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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Identification of heavy, energetic, hadronically decaying particles using machine-learning techniques

Machine-learning (ML) techniques are explored to identify and classify hadronic decays of highly Lorentz-boosted W/Z/Higgs bosons and top quarks. Techniques without ML have also been evaluated and are included for comparison. The identification performances of a variety of algorithms are characterized in simulated events and directly compared with data. The algorithms are validated using proton-proton collision data at $\sqrt{s}$ = 13TeV, corresponding to an integrated luminosity of 35.9 fb -1 . Systematic uncertainties are assessed by comparing the results obtained using simulation and collision data. The new techniques studied in this paper provide significant performance improvements over non-ML techniques, reducing the background rate by up to an order of magnitude at the same signal efficiency.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Search for events with one displaced vertex from long-lived neutral particles decaying into hadronic jets in the ATLAS muon spectrometer in 𝑝⁢𝑝 collisions at $\sqrt{𝑠}$ = 13 TeV

A search for events with one displaced vertex from long-lived particles using data collected by the ATLAS detector at the Large Hadron Collider is presented, using 140 fb −1 of proton-proton collision data at $\sqrt{𝑠}$ =13 TeV recorded in 2015–2018. The search employs techniques for reconstructing vertices of long-lived particles decaying into hadronic jets in the muon spectrometer displaced between 3 m and 14 m from the primary interaction vertex. The observed number of events is consistent with the expected background and limits for several benchmark signals are determined. A scalar-portal model and a Higgs-boson-portal baryogenesis model are considered. A dedicated analysis channel is employed to target Z-boson associated long-lived particle production, including an axionlike particle and a dark photon model. For the Higgs boson model, branching fractions above 1% are excluded at 95% confidence level for long-lived particle proper decay lengths ranging from 5 cm to 40 m. For the photophobic axionlike particle model considered, this search produces the strongest limits to date for proper decay lengths greater than 𝒪⁡(10) cm.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Observation of the rare decay B{sup 0}{yields}K{sub S}{sup 0}K{sup {+-}}{pi}{sup {+-}}

We report an analysis of charmless hadronic decays of neutral B mesons to the final state K{sub S}{sup 0}K{sup {+-}}{pi}{sup {+-}}, using a data sample of (465{+-}5)x10{sup 6} BB events collected with the BABAR detector at the {Upsilon}(4S) resonance. We observe an excess of signal events with a significance of 5.2 standard deviations including systematic uncertainties and measure the branching fraction to be B(B{sup 0}{yields}K{sub S}{sup 0}K{sup {+-}}{pi}{sup {+-}})=(3.2{+-}0.5{+-}0.3)x10{sup -6}, where the uncertainties are statistical and systematic, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Strong Decays of Heavy Baryons in the {sup 3}P{sub 0} Model

The results of a recent quark model for the spectrum of heavy baryons are presented. Comparison of the experimental spectrum with the model masses allow the quantum numbers of a number of experimental states to be inferred. However, the quantum numbers of a number of the experimental states remain ambiguous, as more than one model state is predicted to have a mass similar to the experimental mass. This ambiguity can be removed by examining other properties of the states, such as their hadronic decays. Future work on these strong decays is outlined.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Propagation in the atmosphere of ultrahigh-energy charmed hadrons

Charmed mesons may be produced when a primary cosmic ray or the leading hadron in an air shower collide with an atmospheric nucleon. At energies {>=}10{sup 8} GeV their decay length becomes larger than 10 km, which implies that they tend to interact in the air instead of decaying. We study the collisions of long-lived charmed hadrons in the atmosphere. We show that ({Lambda}{sub c},D)-proton diffractive processes and partonic collisions of any q{sup 2} where the charm quark is a spectator have lower inelasticity than (p,{pi})-proton collisions. In particular, we find that a D meson deposits in each interaction just around 55% of the energy deposited by a pion. On the other hand, collisions involving the valence c-quark (its annihilation with a sea c-quark in the target or c-quark exchange in the t channel) may deposit most of the D meson energy, but their frequency is low (below 0.1% of inelastic interactions). As a consequence, very energetic charmed hadrons may keep a significant fraction of their initial energy after several hadronic interactions, reaching much deeper in the atmosphere than pions or protons of similar energy.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Heavy Hadron Molecules

The open charm mesons D{sub s0}*(2317), D{sub s1}(2460) and the hidden charm meson X(3872) are discussed as hadron molecules. Using a phenomenological Lagrangian approach we consider the strong and radiative decays of the D{sub s0}*(2317) and D{sub s1}(2460) states. The X(3872) is assumed to consist dominantly of molecular hadronic components with an additional small admixture of a charmonium configuration. Observed radiative ({gamma}J/{psi} and {gamma}{psi}(2s)) and strong (J/{psi}2{pi} and J/{psi}3{pi}) decays are shown to be consistent with the molecular structure assumption of the X(3872).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Spin correlations in the {Lambda}{Lambda} and {Lambda}{Lambda}-bar systems generated in relativistic heavy-ion collisions

Spin correlations for the {Lambda}{Lambda} and {Lambda}{Lambda}-bar pairs, generated in relativistic heavy-ion collisions, and related angular correlations at the joint registration of hadronic decays of two hyperons, in which space parity is not conserved, are analyzed. The correlation tensor components can be derived from the double angular distribution of products of two decays by the method of 'moments'. The properties of the 'trace' of the correlation tensor (a sum of three diagonal components), determining the relative fractions of the triplet states and singlet state of respective pairs, are discussed. Spin correlations for two identical particles ({Lambda}{Lambda}) and two nonidentical particles ({Lambda}{Lambda}-bar) are considered from the viewpoint of the conventional model of one-particle sources. In the framework of this model, correlations vanish at sufficiently large relative momenta. However, under these conditions, in the case of two nonidentical particles ({Lambda}{Lambda}-bar) a noticeable role is played by two-particle annihilation (two-quark, two-gluon) sources, which lead to the difference of the correlation tensor from zero. In particular, such a situation may arise when the system passes through the 'mixed phase.'

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Observation of the Rare Decay B+ \to K+pi0pi0 and Measurement of the Quasi-two Body Contributions B+ \to K*(892)+pi0, B+ \to f0(980)K+ and B+ \to chic0K+

We report an analysis of charmless hadronic decays of charged B mesons to the final state K{sup +}{pi}{sup 0}{pi}{sup 0}, using a data sample of (470.9 {+-} 2.8) x 10{sup 6} B{bar B} events collected with the BABAR detector at the {Gamma}(4S) resonance. We observe an excess of signal events, with a significance above 10 standard deviations including systematic uncertainties, and measure the branching fraction and CP asymmetry to be {Beta}(B{sup +} {yields} K{sup +}{pi}{sup 0}{pi}{sup 0}) = (16.2 {+-} 1.2 {+-} 1.5) x 10{sup -6} and A{sub CP}(B{sup +} {yields} K{sup +}{pi}{sup 0}{pi}{sup 0}) = -0.06 {+-} 0.06 {+-} 0.04, where the uncertainties are statistical and systematic, respectively. Additionally, we study the contributions of the B{sup +} {yields} K{sup +}(892){sup +}{pi}{sup 0}, B{sup +} {yields} f{sub 0}(980)K{sup +}, and B{sup +} {yields} {chi}{sub c0}K{sup +} quasi-two-body decays. We report the world's best measurements of the branching fraction and CP asymmetry of the B{sup +} {yields} K{sup +}{pi}{sup 0}{pi}{sup 0} and B{sup +} {yields} K{sup +}(892){sup +}{pi}{sup 0} channels.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Hadronic decay width from finite-volume energy spectrum in lattice QCD

The standard approach to determine the parameters of a resonance is based on the study of the volume dependence of the energy spectrum. In this work we study a non-linear sigma model coupled to a scalar field in which a resonance emerges. Using an analysis method introduced recently, based on the concept of probability distribution, it is possible to determine the mass and the width of the resonance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Search for the decay J/{psi}{yields}{gamma}+invisible

A search for J/{psi} radiative decay to weakly interacting neutral final states was performed using the CLEO-c detector at the Cornell Electron Storage Ring. J/{psi} events were selected by observing the hadronic decay {psi}(2S){yields}{pi}{sup +{pi}-}J/{psi}. A total of 3.7x10{sup 6} J/{psi} events were used to study the decay J/{psi}{yields}{gamma}+X, where X is a narrow state that is invisible to the detector. No significant signal was observed, and upper limits on the branching fraction were set for masses m{sub X} up to 960 MeV/c{sup 2}. The upper limit corresponding to m{sub X}=0 is 4.3x10{sup -6} at the 90% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Possible signatures of new physics in bottomonium spectroscopy and decays

A light CP-odd Higgs can show up in bottomonium spectroscopy and decays by mixing with pseudoscalar {eta}{sub b} hadronic resonances. We study the phenomenological consequences within the Next-to-Minimal- Supersymmetric-Standard-Model (NMSSM) of such a mixing leading to possible lepton universality breaking (up to a few percent level) in Upsilon decays, and anomalous hyperfine splittings m{sub {Upsilon}(nS)}-m{sub {eta}{sub b(nS)}}, to be observed at (Super) B factories.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Study of kaonic final states in {pi}{sup -} p at 190 GeV

We discuss the status of analyses of data recorded in the 2008 and 2009 runs of the COMPASS experiment at CERN with sepcific focus on final states with K{sub S}{sup 0}K{sub S}{sup 0{pi}}- and K{sup +}K{sup -{pi}-} produced in {pi}{sup -}(190 GeV)p scattering. The interest in such final states is motivated by a summary of some of the relevant literature. We also show first results from the analysis of diffractively produced KK-bar{pi} states. Two prominent three-body structures, one around 1.8 GeV, the other at 2.2 GeV decaying via known KK-bar and K{pi} states are seen.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Medium-induced modification of azimuthal correlations of electrons from heavy-flavor hadron decays with charged particles in Pb–Pb collisions at $\mathbf {\sqrt{s_{\textrm{NN}}} = 5.02}$ TeV

The azimuthal-correlation distributions between electrons from the decays of heavy-flavor hadrons and associated charged particles in Pb–Pb collisions at $\sqrt{s_{\textrm{NN}}} = 5.02$ TeV are reported for the 0–10% and 30–50% centrality classes. This measurement provides access to the jet-like correlation observables in the heavy-flavor sector in Pb–Pb collisions. The analysis is performed for trigger electrons from heavy-flavor hadron decays with transverse momentum $4< p_\textrm{T}^\textrm{e} < 16~\textrm{GeV}/c$, considering associated particles within the transverse-momentum range $1< p_\textrm{T}^\textrm{assoc} < 7$ GeV/c, and a pseudorapidity difference of $|\Delta \eta |<1$ between the trigger electron and associated particles. The per-trigger nuclear modification factor ( I AA ) is calculated to compare the near- and away-side peak yields to those in pp collisions at $\sqrt{s} = 5.02$ TeV. In 0–10% central collisions, the indicates a hint of enhancement of associated-particle yields with $p_\textrm{T}<3$ GeV/c on the near side, and a suppression of yields with $p_\textrm{T}>4$ GeV/c on the away side. The I AA for electron triggers from heavy-flavor hadron decays is compared with that for light-flavor and strange-particle triggers to investigate the dependence on different fragmentation processes and parton-medium dynamics, and is found to be the same within uncertainties.

Abualrob, I. J. [University of Houston] (ORCID:000↗
DOE OSTI2013

Inclusive τ lepton decay: the effects due to hadronization

Theoretical description of inclusive τ lepton hadronic decay is performed in the framework of Dispersive approach to QCD. The significance of effects due to hadronization is demonstrated. The approach on hand is capable of describing experimental data on τ lepton hadronic decay in vector and axial-vector channels. The vicinity of values of QCD scale parameter obtained in both channels testifies to the self-consistency of developed approach.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Updated measurements of hadronic B decays at CDF

The CDF experiment at the Tevatron p{bar p} collider established that extensive and detailed exploration of the b-quark dynamics is possible in hadron collisions, with results competitive and supplementary to those from e{sup +}e{sup -} colliders. This provides a rich, and highly rewarding program that has currently reached full maturity. In the following I report some recent results on hadronic decays: the evidence for the charmless annihilation decay mode B{sub s}{sup 0} {yields} {pi}{sup +}{pi}{sup -}, and the first reconstruction in hadron collisions of the suppressed decays B{sup -} {yields} D({yields} K{sup +}{pi}{sup 0})K{sup -} and B{sup -} {yields} D({yields} K{sup +} {pi}{sup -}){pi}{sup -}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Reparametrization invariance constraints on inclusive decay spectra and masses

Reparametrization invariance relations are determined for the inclusive decay spectra of heavy hadrons. They connect the leading-order result to the {lambda}{sub 1} term, and the {lambda}{sub 2} and {rho}{sub 2} terms, and imply that the {lambda}{sub 1} and {rho}{sub 2} terms in the total rate occur in the combinations 1+{lambda}{sub 1}/(2m{sub Q}{sup 2}) and {lambda}{sub 2}-{rho}{sub 2}/m{sub Q}. The relations are satisfied by the known results for the hadronic decay tensors for B{yields}X{sub c,u}l{nu}, B{yields}X{sub s{gamma}} and B{yields}X{sub s}l{sup +}l{sup -} decays. An interesting field-theory result, the connection between currents in full and effective theories and the change in currents under field redefinitions, is discussed, and is used to determine the effective theory operator whose hadron matrix element is unity to all order in 1/m{sub Q}. The hadron masses are given to order {Lambda}{sub QCD}{sup 3}/m{sub Q}{sup 2} including radiative corrections, and provide an example illustrating the relation between renormalization and reparametrization invariance and {mu}-independence of 1/m{sub Q}{sup 3} corrections to physical quantities.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗