Observation of Three Charmoniumlike States with J P C = 1 − − in e + e − → D * 0 D * − π +
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
SEARCH · Engineering Papers
Results for “Elementary Particle Interactions”
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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Improved Measurement of the Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Simultaneous Measurement of Muon Neutrino ν μ Charged-Current Single π + Production in CH, C, H 2 O , Fe, and Pb Targets in MINERvA
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Comprehensive Measurement of the Reactor Antineutrino Spectrum and Flux at Daya Bay
This Letter reports the precise measurement of the reactor antineutrino spectrum and flux based on the full dataset of 4.7 ×10 6 inverse-beta-decay candidates collected at Daya Bay near detectors. Expressed in terms of the inverse-beta-decay yield per fission, the antineutrino spectra from all reactor fissile isotopes and the specific 235 U and 239 Pu isotopes are measured with 1.3%, 3%, and 8% uncertainties, respectively, near the 3 MeV spectrum peak in reconstructed energy, reaching the best precision in the world. The total antineutrino flux and isotopic 235 U and 239 Pu fluxes are precisely measured to be 5.84 ± 0.07, 6.16 ± 0.12, and 4.16 ± 0.21 in units of 10 −43 cm 2 /fission. These measurements are compared with the Huber-Mueller model, the reevaluated conversion model based on the Kurchatov Institute measurement, and the latest summation model (SM2023). Furthermore, the Daya Bay flux shows good consistency with the Kurchatov Institute and SM2023 models but disagrees with the Huber-Mueller model. The Daya Bay spectrum, however, disagrees with all model predictions.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for Lepton-Flavor-Violating Decay Modes 𝐵 0 →𝐾$^0_𝑆$𝜏 ± ℓ ∓ with Hadronic 𝐵 Tagging at Belle and Belle II
We present the first search for the lepton-flavor-violating decay modes 𝐵 0 →𝐾$^0_𝑆$𝜏 ± ℓ ∓ (ℓ=𝜇,𝑒) using the 711 and 365 fb −1 data samples recorded by the Belle and Belle II detectors, respectively. We use a hadronic 𝐵-tagging technique to fully reconstruct a 𝐵 meson and search for signal decays in the system recoiling against the tagged meson, considering 𝜏 decays to either light leptons, one charged hadron, or one charged hadron and a neutral pion. We find no evidence for 𝐵 0 →𝐾$^0_𝑆$𝜏 ± ℓ ∓ decays and set 90% confidence level upper limits on the branching fractions in the range of [0.8,3.6] ×10 −5 .
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
The Standard Model Theory of Neutron Beta Decay
We review the status of the Standard Model theory of neutron beta decay. Particular emphasis is put on the recent developments in the electroweak radiative corrections. Given that some existing approaches give slightly different results, we thoroughly review the origin of discrepancies, and provide our recommended value for the radiative correction to the neutron and nuclear decay rates. The use of dispersion relation, lattice Quantum Chromodynamics, and an effective field theory framework allows for high-precision theory calculations at the level of 10 –4 , turning neutron beta decay into a powerful tool to search for new physics, complementary to high-energy collider experiments. We offer an outlook to the future improvements.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Chirally symmetric and confining dense matter with a diffused quark Fermi surface
It is possible that at low temperatures and large density there exists a confining matter with restored chiral symmetry, just after the dense nuclear matter with broken chiral symmetry. Such a phase has, so far, been studied within a confining and chirally symmetric model, assuming a rigid quark Fermi surface. In the confining quarkyonic matter, however, near the Fermi surface, quarks group into color-singlet baryons. Interaction between quarks leads to a diffusion of the quark Fermi surface. Here, we study effects of such diffusion and verify that it does not destroy a possible existence of a confining but chirally symmetric matter at low temperatures.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Magnon energy renormalization and low-temperature thermodynamics of O(3) Heisenberg ferromagnets
We present the perturbation theory for lattice magnon fields of the D-dimensional O(3) Heisenberg ferromagnet. The effective Hamiltonian for the lattice magnon fields is obtained starting from the effective Lagrangian, with two dominant contributions that describe magnon–magnon interactions identified as a usual gradient term for the unit vector field and a part originating in the Wess–Zumino–Witten term of the effective Lagrangian. Feynman diagrams for lattice scalar fields with derivative couplings are introduced, on the basis of which we investigate the influence of magnon–magnon interactions on magnon self-energy and ferromagnet free energy. We also comment appearance of spurious terms in low-temperature series for the free energy by examining magnon–magnon interactions and internal symmetry of the effective Hamiltonian (Lagrangian). -- Highlights: •Lattice magnon Hamiltonian constructed from the effective Lagrangian. •New Feynman diagrams with colored propagators and vertices for lattice scalar fields. •Influence of magnon–magnon interactions from the WZW term on magnon energies and free energy of O(3) HFM.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Fourth order spatial derivative gravity
In this work, we study a modified theory of gravity that contains up to fourth order spatial derivatives as a model for the Horava-Lifshitz gravity. The propagator is evaluated and, as a result, one extra pole is obtained, corresponding to a spin-2 nonrelativistic massless particle, an extra term which jeopardizes renormalizability, besides the unexpected general relativity unmodified propagator. Then unitarity is proved at the tree level, where the general relativity pole has been shown to have no dynamics, remaining only the 2 degrees of freedom of the new pole. Next, the nonrelativistic effective potential is determined from a scattering process of two identical massive gravitationally interacting bosons. In this limit, Newton's potential is obtained, together with a Darwin-like term that comes from the extra nonpole term in the propagator. Regarding renormalizability, this extra term may be harmful by power counting, but it can be eliminated by adjusting the free parameters of the model. This adjustment is in accord with the detailed balance condition suggested in the literature and shows that the way in which extra spatial derivative terms are added is of fundamental importance.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Hadron spectrum and infrared-finite behavior of QCD running coupling
We study the behavior of the QCD effective coupling α{sub s} in the low-energy region by exploiting the conventional meson spectrum within a relativistic quantum-field model based on analytical confinement of quarks and gluons. The spectra of quark-antiquark and two-gluon bound states are defined by using a master equation similar to the ladder Bethe-Salpeter equation. A new, independent and specific infrared-finite behavior of QCD coupling is found below energy scale ∼1 GeV. Particularly, an infrared-fixed point is extracted at α{sub s}(0) ≅ 0.757 for confinement scale Λ = 345 MeV. We provide a new analytic estimate of the lowest-state glueball mass. As applications, we also estimate masses of some intermediate and heavy mesons as well as the weak-decay constants of light mesons. By introducing only a minimal set of parameters (the quark masses m{sub f} and Λ) we obtain results in reasonable agreement with recent experimental data in a wide range of energy scale ∼0.1–10 GeV. We demonstrate that global properties of some low-energy phenomena may be explained reasonably in the framework of a simple relativistic quantum-field model if one guesses correct symmetry structure of the quark-gluon interaction in the confinement region and uses simple forms of propagators in the hadronisation regime. The model may serve a reasonable framework to describe simultaneously different sectors in low-energy particle physics.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Dynamical symmetry breaking in models with the Yukawa interaction
The models with a massless fermion and a self-interacting massive scalar field with the Yukawa interaction are discussed. The chiral condensate and the fermion mass are calculated analytically through a one-loop approximation in (1 + 1)-dimensions. It is shown that the models have a phase transition as a function of the squared mass of the scalar field.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Probing the Triple Higgs Self-Interaction at the Large Hadron Collider
Not Available
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Pseudotensor mesons as three-body resonances
We show that the lightest pseudotensor mesons J{sup PC}=2{sup -+} can be regarded as molecules made of a pseudoscalar (P) 0{sup -+} and a tensor 2{sup ++} meson, where the latter is itself made of two vector (V) mesons. The idea stems from the fact that the vector-vector interaction in s wave and spin 2 is very strong, to the point of generating the 2{sup ++} tensor mesons. On the other hand the interaction of a pseudoscalar with a vector meson in s wave is also very strong and it generates dynamically the lightest axial-vector mesons. Therefore we expect the PVV interaction to be strongly attractive and thus able to build up quasibound PVV resonances. We calculate the three-body PVV interaction by using the fixed center approximation to the Faddeev equations where the two vectors are clustered forming a tensor meson. We find clear resonant structures which can be identified with the {pi}{sub 2}(1670), {eta}{sub 2}(1645) and K{sub 2}{sup *}(1770) (2{sup -+}) pseudotensor mesons.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Weak and electromagnetic mechanisms of neutrino-pair photoproduction in a strongly magnetized electron gas
Expressions for the power of neutrino radiation from a degenerate electron gas in a strong magnetic field are derived for the case of neutrino-pair photoproduction via the weak and electromagnetic interaction mechanisms (it is assumed that the neutrino possesses electromagnetic form factors). It is shown that the neutrino luminosity of a medium in the electromagnetic reaction channel may exceed substantially the luminosity in the weak channel. Relative upper bounds on the effective neutrino magnetic moment are obtained.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Collaborative Research: Tomographic imaging of laser-plasma structures
The interaction of intense short laser pulses with ionized gases, or plasmas, underlies many applications such as acceleration of elementary particles, production of energy by laser fusion, generation of x-ray and far-infrared “terahertz” pulses for medical and materials probing, remote sensing of explosives and pollutants, and generation of guide stars. Such laser-plasma interactions create tiny electron density structures (analogous to the wake behind a boat) inside the plasma in the shape of waves, bubbles and filaments that move at the speed of light, and evolve as they propagate. Prior to recent work by the PI of this proposal, detailed knowledge of such structures came exclusively from intensive computer simulations. Now “snapshots” of these elusive, light-velocity structures can be taken in the laboratory using dynamic variant of holography, the technique used to produce ID cards and DVDs, and dynamic variant of tomography, the technique used in medicine to image internal bodily organs. These fast visualization techniques are important for understanding, improving and scaling the above-mentioned applications of laser-plasma interactions. In this project, we accomplished three things: 1) We took holographic pictures of a laser-driven plasma-wave in the act of accelerating electrons to high energy, and used computer simulations to understand the pictures. 2) Using results from this experiment to optimize the performance of the accelerator, and the brightness of x-rays that it emits. These x-rays will be useful for medical and materials science applications. 3) We made technical improvements to the holographic technique that enables us to see finer details in the recorded pictures. Four refereed journal papers were published, and two students earned PhDs and moved on to scientific careers in US National Laboratories based on their work under this project.
43 PARTICLE ACCELERATORS↗
Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in root s=13 TeV pp collisions with the ATLAS detector
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
The performance of the LHCf detector
The LHCf experiment is designed to measure energies and transverse momenta of neutral particles emitted in the forward region of {radical}(s) = 14 TeV p-p collision at {+-}140 m away from the interaction point1 (IP1) of LHC. The energy resolution is confirm to be within 5% and the position resolution is better than 0.2 mm for gamma-rays with energies from 100 GeV to 200 GeV by the test beam results at the CERN-SPS. LHCf has taken data at 2009 and 2010 at {radical}(s) = 900 GeV and 7 TeV collision. A brief summary of LHCf operation at LHC is also reported here.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
More on loops in reheating: non-gaussianities and tensor power spectrum
We consider the single field chaotic m{sup 2}ϕ{sup 2} inflationary model with a period of preheating, where the inflaton decays to another scalar field χ in the parametric resonance regime. In a recent work, one of us has shown that the χ modes circulating in the loops during preheating notably modify the <ζζ> correlation function. We first rederive this result using a different gauge condition hence reconfirm that superhorizon ζ modes are affected by the loops in preheating. Further, we examine how χ loops give rise to non-gaussianity and affect the tensor perturbations. For that, all cubic and some higher order interactions involving two χ fields are determined and their contribution to the non-gaussianity parameter f{sub NL} and the tensor power spectrum are calculated at one loop. Our estimates for these corrections show that while a large amount of non-gaussianity can be produced during reheating, the tensor power spectrum receive moderate corrections. We observe that the loop quantum effects increase with more χ fields circulating in the loops indicating that the perturbation theory might be broken down. These findings demonstrate that the loop corrections during reheating are significant and they must be taken into account for precision inflationary cosmology.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗