نتایج جستجو برای: photon collision
تعداد نتایج: 116904 فیلتر نتایج به سال:
We search for single-photon events in 53 fb^{-1} of e^{+}e^{-} collision data collected with the BABAR detector at the PEP-II B-Factory. We look for events with a single high-energy photon and a large missing momentum and energy, consistent with production of a spin-1 particle A^{'} through the process e^{+}e^{-}→γA^{'}; A^{'}→invisible. Such particles, referred to as "dark photons," are motiv...
The photon splitting is the process with minimal rank of nonlinearity in the electromagnetic interactions. This kind of reaction is to be realized in various astrophysical objects (white dwarves, neutron stars), the early Universe and in the heavy ion collision experiments. In all these cases Furry’s theorem is violated because of the presence of the environments such as external fields or dens...
چکیده ندارد.
We derive a simple expression for the photon helicity and polarisation-flip probabilities in arbitrary background fields, in the low energy regime. Taking the background to model a focused laser beam, we study the impact of pulse shape and collision geometry on the probabilities and on ellipticity signals of vacuum birefringence. We find that models which do not account for pulse duration can o...
We investigate the transition of the polarized photon structure function g 1 (x,Q , P ) when the target photon shifts from on-shell (P 2 = 0) to far off-shell (P 2 ≫ Λ) region. The analysis is performed to the nextto-leading order in QCD. The first moment of g 1 which vanishes for the real photon, turns to be a negative value when target photon becomes off-shell. The explicit P -dependence of t...
InfraRed Multiple Photon Dissociation (IRMPD) spectroscopy was used to assay the structural features of the fragment ions resulting from the elimination of H3PO4 in the Collision-Induced Dissociation (CID) of protonated serine. The results are interpreted with the aid of density functional theory calculations. Experiment and theory point to an aziridine-ring structure, implying participation of...
Infrared multiple photon dissociation (IRMPD) spectroscopy is used to identify the structure of the b(2)(+) ion generated from protonated tri-alanine by collision induced dissociation (CID). The IRMPD spectrum of b(2)(+) differs markedly from that of protonated cyclo-alanine-alanine, demonstrating that the product is not a diketopiperazine. Instead, comparison of the IRMPD spectrum of b(2)(+) t...
Highlights on recent measurements of top quark properties in ATLAS, using pp collision data at √ s= 8 TeV and 13 TeV, are presented. The measurements of the top quark polarization and spin correlation coefficients, the W boson helicity fractions, the structure of the Wtb vertex, the associated production of a tt̄ pair with a vector boson or a photon, and the top quark mass are all in agreement w...
Single W -boson production in eγ collisions with polarized beams is investigated. In the framework of the Standard Model the updated estimates for the measurement precision of photon anomalous coupling parameters κγ , λγ at the Next Linear Collider with √ seγ = 420 GeV are obtained. The production of right-handed gauge bosons W 2 in this collision mode is also analysed. If the associated neutri...
A soft photon approximation is used to calculate the rates of lepton pair production through virtual bremsstrahlung from both pions and quarks. Standard assumptions about the evolution of a nuclear system under collision allow pion and quark driven total production to be calculated. Comparisons are made with Dalitz decay of light mesons. These mechanisms are expected to be significant contribut...
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