Results 1 - 10 of 11899
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[en] The history of the isospin concept is reviewed from the introduction of the formalism by Heisenberg in 1932 to the isospin selection rules of Adair, Radicati, and Gell-Mann and Telegdi of the early 1950s, and the significance of the concept is assessed. 34 refs
[en] We develop an isospin-like formulation with particles and their antiparticle counterparts. This leads to a new shortlived interaction between them, valid at very high energies and mediated by massive particles. We point out that evidence for this is already suggested by the very recent observations by the CDF collaboration at Fermilab. (author)
[en] The analysis of the instanton contribution for the CP1-model with periodic boundary conditions is performed using isospin invariance. An interpretation in terms of a neutral Coulomb gas is given
[en] We present an analysis of the decays B0 → K*0(892)γ and B+ → K*+(892)γ using a sample of about 383 million B(bar B) events collected with the BABAR detector at the PEP-II asymmetric energy B factory. We measure the branching fractions Β(B0 → K*0γ) = (4.47 ± 0.10 ± 0.16) x 10-5 and Β(B+ → K*+γ) = (4.22 ± 0.14 ± 0.16) x 10-5. We constrain the direct CP asymmetry to be -0.033 < Α(B → K*γ) < 0.028 and the isospin asymmetry to be 0.017 < Δ0- < 0.116, where the limits are determined by the 90% confidence interval and include both the statistical and systematic uncertainties.
[en] Isobaric analogues of three states in "1"0Be forming a rotational band with high moment of inertia are expected in "1"0B and "1"0C. This article reports a measurement of excitation spectrum in "1"0B obtained through "1"1B("3He,α)"1"0B reaction. A T = 1 state is found on 11.3 MeV excitation energy. It is a possible candidate for the 4"+ state of the analogue rotation band. (author)
[en] Various aspects observed in the reactions 40Ca+40,48 Ca,46Ti at E=25 MeV/nucleon, studied by means of the CHIMERA detector, will be discussed. An isospin effect on the competition between heavy residue production and binary-like channels has been observed in incomplete fusion events. From the thermodynamical point of view, kinetic energy spectra of protons emitted in fusion-evaporation events were fitted with two Maxwellian functions. Despite the different neutron richness of the populated sources, the average temperatures obtained for the quasi-fused systems are similar (T≃5.2MeV). We also performed a preliminary reconstruction of the excitation energy reached by quasi-fusion sources populated in the studied reactions. (author)
[en] The α-decay half-lives for the even–even, even–odd, odd–even and odd–odd of 356 nuclei in the range have been studied within the analytical formula of Royer and also within the modified analytical formula of Royer. We calculated the new coefficient of the Royer by fitting 356 isotopes. Also, we considered the Denisov and Khudenko formula and obtained the new coefficient for the modified Denisov and Khudenko formula. We calculated the standard deviation and the average deviation. Analytical results are compared with the experimental data. The results are in better agreement with the experimental data when the effect of the isospin considered for the parent nuclei.
[en] Generalizing the Dirac equation, one introduces the pionic field and associates the isospin with rotations of the proper space by relativistic invariance. The strangeness S of the doublet XI is determined and divergences of isovectors allow the calculation of the charge with the help of pionic components on isovectors. The signs of magnetic moments, the non-existence of a strange and baryonic doublet with charges (0,e+) are explained and sign of differences between the doublet's element are connected
[fr]Generalisant l'equation de Dirac, on introduit le champ pionique et on associe l'isospin aux rotations de l'espace propre sous invariance relativiste. On determine l'etrangete S du doublet XI et les divergences des isovecteurs permettant de calculer la charge en fonction des composantes du champ pionique sur les isovecteurs. On explique l'inexistence d'un doublet baryonique etrange (0,e+), les signes des moments magnetiques et l'on relie les deux signes des differences de masse des elements des doublets