Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “ANTIHYPERONS”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Measurement of antiproton production from antihyperon decays in ${p} \textrm{He}$ collisions at $\sqrt{s_{\scriptscriptstyle \mathrm NN}} =110$ GeV

The interpretation of cosmic antiproton flux measurements from space-borne experiments is currently limited by the knowledge of the antiproton production cross-section in collisions between primary cosmic rays and the interstellar medium. Using collisions of protons with an energy of 6.5 TeV incident on helium nuclei at rest in the proximity of the interaction region of the LHCb experiment, the ratio of antiprotons originating from antihyperon decays to prompt production is measured for antiproton momenta between 12 and 110 GeV/c. The dominant antihyperon contribution, namely ${\overline{\varLambda }} \rightarrow {\overline{{p}}} {{\pi } ^+}$ decays from promptly produced $\overline{\varLambda }$ particles, is also exclusively measured. The results complement the measurement of prompt antiproton production obtained from the same data sample. At the energy scale of this measurement, the antihyperon contributions to antiproton production are observed to be significantly larger than predictions of commonly used hadronic production models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

First Study of Antihyperon-Nucleon Scattering Λ ¯ p → Λ ¯ p and Measurement of Λ p → Λ p Cross Section

Using ( 10.087 ± 0.044 ) × 10 9 J / ψ events collected with the BESIII detector at the BEPCII storage ring, the processes Λ p → Λ p and Λ ¯ p → Λ ¯ p are studied, where the Λ / Λ ¯ baryons are produced in the process J / ψ → Λ Λ ¯ and the protons are the hydrogen nuclei in the cooling oil of the beam pipe. Clear signals are observed for the two reactions. The cross sections in − 0.9 ≤ cos θ Λ / Λ ¯ ≤ 0.9 are measured to be σ ( Λ p → Λ p ) = ( 12.2 ± 1.6 stat ± 1.1 syst ) and σ ( Λ ¯ p → Λ ¯ p ) = ( 17.5 ± 2.1 stat ± 1.6 syst ) mb at the Λ / Λ ¯ momentum of 1.074 GeV / c within a range of ± 0.017 GeV / c , where the θ Λ / Λ ¯ are the scattering angles of the Λ / Λ ¯ in the Λ p / Λ ¯ p rest frames. Furthermore, the differential cross sections of the two reactions are also measured, where there is a slight tendency of forward scattering for Λ p → Λ p , and a strong forward peak for Λ ¯ p → Λ ¯ p . We present an approach to extract the total elastic cross sections by extrapolation. The study of Λ ¯ p → Λ ¯ p represents the first study of antihyperon-nucleon scattering, and these new measurements will serve as important inputs for the theoretical understanding of the (anti)hyperon-nucleon interaction. Published by the American Physical Society 2024

Physics↗
DOE OSTI2025

Probing spin and lifetime correlations in entangled hyperon-antihyperon pairs

Quantum entanglement has now been demonstrated in several hadronic systems, revealing that non-classical spin correlations survive even through the strong-interaction hadronization process. To date, however, all studies have focused exclusively on angular observables, leaving the possibility untouched that quantum coherence might also influence the decay times of entangled partners. In this work we propose data-driven tests of spin-lifetime and lifetime-lifetime correlations for $Λ-\bar{Λ}$ pairs produced in high-energy collisions. By examining the opening-angle distribution in slices of $Δt$, constructing a pair-wise spin-lifetime correlator, and testing a simple lifetime-lifetime covariance, we search for deviations from independent exponential decay that align with known spin correlations. Observation of nonzero lifetime correlations would compel a reassessment of how entanglement manifests in decaying systems, revealing hitherto unexplored temporal coherence.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Extracting the femtometer structure of strange baryons using the vacuum polarization effect

Abstract One of the fundamental goals of particle physics is to gain a microscopic understanding of the strong interaction. Electromagnetic form factors quantify the structure of hadrons in terms of charge and magnetization distributions. While the nucleon structure has been investigated extensively, data on hyperons are still scarce. It has recently been demonstrated that electron-positron annihilations into hyperon-antihyperon pairs provide a powerful tool to investigate their inner structure. We present a method useful for hyperon-antihyperon pairs of different types which exploits the cross section enhancement due to the effect of vacuum polarization at theJ/ψresonance. Using the 10 billionJ/ψevents collected with the BESIII detector, this allows a precise determination of the hyperon structure function. The result is essentially a precise snapshot of the$$\bar{\Lambda }{\Sigma }^{0}\,(\Lambda {\bar{\Sigma }}^{0})$$ Λ ¯ Σ 0 ( Λ Σ ¯ 0 ) transition process, encoded in the transition form factor ratio and phase. Their values are measured to beR = 0.860 ± 0.029(stat.) ± 0.015(syst.),$$\Delta {\Phi }_{\bar{\Lambda }{\Sigma }^{0}}=(1.011\pm 0.094({{\rm{stat.}}})\pm 0.010({{\rm{syst.}}}))\,{{\rm{r}}}ad$$ Δ Φ Λ ¯ Σ 0 = ( 1.011 ± 0.094 ( stat. ) ± 0.010 ( syst. ) ) r a d and$$\Delta {\Phi }_{\Lambda {\bar{\Sigma }}^{0}}=(2.128\pm 0.094({{\rm{stat.}}})\pm 0.010({{\rm{syst.}}}))\,{{\rm{r}}}ad$$ Δ Φ Λ Σ ¯ 0 = ( 2.128 ± 0.094 ( stat. ) ± 0.010 ( syst. ) ) r a d . Furthermore, charge-parity (CP) breaking is investigated in this reaction and found to be consistent with CP symmetry.

Science & Technology - Other Topics↗
DOE OSTI2019

Λ and Λ ¯ spin interaction with meson fields generated by the baryon current in high energy nuclear collisions

We propose a dynamical mechanism which provides an interaction between the spins of hyperons and antihyperons and the vorticity of the baryon current in noncentral high energy nuclear collisions. The interaction is mediated by massive vector and scalar bosons, which is well known to describe the nuclear spin-orbit force. It follows from the Foldy-Wouthuysen transformation and leads to a strong-interaction Zeeman effect. The interaction may explain the difference in polarizations of Λ and Λ¯ hyperons as measured by the STAR Collaboration at the BNL Relativistic Heavy Ion Collider. Here, the signs and magnitudes of the meson-baryon couplings are closely connected to the binding energies of hypernuclei and to the abundance of hyperons in neutron stars.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Charmed matter

In the near future experiments will be able to produce charmed hadrons almost at rest in the interior of an atomic nucleus. One of the most exciting perspectives is the possibility of studying charmonium in a dense medium. In the present communication we present results of a study that explores the possibility that J/{Psi} might be bound in a large nucleus through the excitation of intermediate states of D and D* mesons. We also present results of a recent prediction for the production of {Lambda}(bar sign){sub c}{sup -{Lambda}}{sub c}{sup +} in proton-antiproton annihilation experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Polarization effects in heavy ion collisions

Recent experiments at RHIC have shown that in 200 GeV Au-Au collisions, the {Lambda} and {Lambda}-bar hyperons are produced with very small polarizations, almost consistent with zero. These results can be understood in terms of a model that we recently proposed. In this work, we show how this model may be applied in such collisions, and also will discuss the relation of our results with other models, in order to explain the experimental data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Average formation lengths of baryons and antibaryons in a string model

In this work the investigation of the space-time scales of the hadronization process in the framework of a string model is continued. The average formation lengths of several widely used species of baryons (antibaryons) such as p(p-bar), n(n-bar), {Delta}({Delta}-bar), {Lambda}({Lambda}-bar), and {Sigma}({Sigma}-bar) are studied. It is shown that they depend on electrical charges or, more precisely, on the quark contents of the hadrons. In particular, the average formation lengths of positively charged hadrons, for example, protons, are considerably larger than those of their negatively charged antiparticles, antiprotons. This statement for all nuclear targets and any values of the Bjorken scaling variable x{sub Bj} is fulfilled. The main mechanism is direct production. Additional production mechanism as a result of the decay of resonances gives small contribution. It is shown that the average formation lengths of protons (antiprotons) are slowly increasing (decreasing) functions of x{sub Bj}, whereas the ones of neutrons and antineutrons are slowly decreasing functions of x{sub Bj}. The shape and behavior of average formation lengths for baryons qualitatively coincide with the ones for pseudoscalar mesons obtained earlier.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Production of strange secondaries in high-energy {Sigma}{sup -}A collisions

The WA89 Collaboration experimental data on production of {Lambda}, {Sigma}{sup -}, {Sigma}{sup +}, {Xi}{sup -}, {Omega}{sup -} baryons, {Lambda}-bar and {Xi}{sup +} antibaryons in {Sigma}{sup -} collisions with C and Cu targets at 345 GeV/c ({radical}s{sub {Sigma}N} Almost-Equal-To 25.5 GeV) in the frame of the Quark-Gluon String Model is described. The comparison of the theoretical results with the experimental data is discussed. Finally, some relations among the values of the model parameters obtained with the help of quark combinatorics are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗