18467789
Putting non Point-like Behavior of Fundamental Particles to Test
We review the experimental limits on those hypothetical interactions where the fundamental particles could exhibit non point-like behavior. In particular we have focused on the QED reaction measuring the differential cross sections for the process $ \EEGG $ at energies around 91 GeV and 209 GeV with data collected from the L3 detector from 1991 to 2001. With a global fit L3 set lower limits at $ 95 % $ CL on a contact interaction energy scale parameter $\Lambda > 1.6 $ TeV, which restricts the characteristic QED size of the interaction region to $ R_{e} < 1.2 \times 10^{-17} $ cm. All the interaction regions are found to be smaller than the Compton wavelength of the fundamental particles. This constraint we use to estimate a lower limit on the internal density of particle-like structure with the de Sitter vacuum core. Some applications of obtained limits to the string and quantum gravity scales are also discussed.
117183376
Test of non point‐like behavior of Fermions
We search in measurements from LEP, TRISTAN, CDF, D0 and UA1 for those phenomena beyond the Standard Model where the fundamental particles can exhibit non point‐like behavior. The total and differential cross sections for the reaction e+e− → γγ(γ) measured at center‐of‐mass energies from 55 GeV to 207 GeV are used for a global fit to test the hypothesis of an excited electron and contact interaction induced terms. The best value for the fit exhibits an approximately 5 σ effect for the scale factor of an excited electron of (1/Λ±4)best = −(1.11 ± 0.20) × 10−10 GeV−4 and the scale of contact interaction of (1/Λ4)best = −(4.05 ± 0.73) × 10−13 GeV−4 but with the opposite to the expected in the modified cross section sign. An empirical scheme is discussed to encompass all fermions and bosons in one framework, if these particles would be geometrically extended objects.
326670
Limits on sizes of fundamental particles and on gravitational mass of a scalar
We review the experimental limits on mass of excited fundamental particles and contact interaction energy scale parameters Λ for QCD, QED and electroweak reactions. In particular we have focused on the QED reaction measuring the differential cross-sections for the process e+e−→γγ(γ) at the energies from 91 GeV to 202 GeV using the data collected with the L3 detector from 1991 to 1999. With a global fit we set lower limits at 95% CL on Λ>1687 GeV, which restricts the characteristic QED size of the interaction region to Re<1.17×10−17 cm. All the interaction regions are found to be smaller than the Compton wavelength of the fundamental particles. This constraint is used to estimate a lower limit on the size of a fundamental particle related to gravitational interaction, applying the model of self-gravitating particle-like structure with the de Sitter vacuum core. It gives rτ⩾2.3×10−17 cm and re⩾1.5×10−18 cm, if leptons get masses at the electroweak scale, and rτ⩾3.3×10−27 cm,re⩾4.9×10−26 cm, as the most stri...
119135529
Orbifold Vortex and Super Liouville Theory
We study the nonabelian vortex counting problem on $\mathbb{C}/\mathbb{Z}_p$. At first we calculate vortex partition functions on the orbifold space using localization techniques, then we find how to extract orbifold vortex partitions function from orbifold linear quiver instanton partition functions. Finally, we study the AGT like relation between orbifold SU(2) vortices and $\mathcal{N} = 1$ super Liouville theory in the mixed R/NS sector by fixing the dictionary among parameters in the common hypergeometric functions system.
32125097
PRELIMINARY RESULTS OF H2+ BEAM GENERATED BY A 2.45 GHZ PERMANENT MAGNET ECR ION SOURCE AT PKU
To obtain high-yield H2 ion beam, experimental and theoretical study was carried out on the 2.45 GHz Peking University permanent magnet electron cyclotron resonance ion source (PKU PMECRIS). With PMECR II [1], studies on the size of discharge chamber and the operation pressure were carried out to increase H2 ion fraction. Beam analysis results prove that the H2 can reach 47.7% with suitable operation parameters. More details will be presented in this paper. INTRODUCTION The creation of molecular ion H2 is an essential process in hydrogen gas plasma. For proton ion source, H2 ions are undesirable in the final extract beam. But recently, the demand to build an ion source to generate high current hydrogen molecular ion H2 beam has been growing rapidly. For example, H2 ion can be used as a pilot beam of the intense deuteron beam during the commissioning of linear accelerators to minimize the activation of components.[2][3] Also it is an effective way to improve the output current of cyclotrons by accelerating H2 and stripping it into H at the exit of accelerator, instead of accelerating H beam directly.[4][5] R. F. King et al. proposed a one-dimensional plasma model for a volume arc source, which is expected to produce 140 mA of ion beam with H2 species ratio around 73% in theory, but it wasn’t realized.[6] N. Joshi et al. developed a volume type ion source at Frankfurt University, and about 91% H2 was extracted with current intensity of 2.84 mA.[7] Obviously, the fraction of H2 is definitely high, but the current is not enough for some applications. With a 2.45 GHz permanent magnet ECR ion source PMECR II [1][8][9] (Fig. 1), the fraction and current intensity of molecular ion H2 were improved at PKU. Theoretical study indicates that, to optimize the production of H2, it is helpful to increase the electron temperature in the source and avoid attachment with neutral H2 which lead to fast destruction of H2.[6] In our PMECRIS, these were achieved by changing the size of discharge chamber and operation pressure in the source. The experimental results will be presented.
119112485
Multidimensionally constrained relativistic mean field model and applications in actinide and transfermium nuclei
We present some results of potential energy surfaces of actinide and transfermium nuclei from multidimensionally constrained relativistic mean field (MDC-RMF) models. Recently we developed multidimensionally constrained covariant density functional theories (MDC-CDFT), in which all shape degrees of freedom beta with even mu are allowed, and the functional can be one of the following four forms: the meson exchange or point-coupling nucleon interactions combined with the nonlinear or density-dependent couplings. In MDC-RMF models, the pairing correlations are treated with the BCS method. With MDC-RMF models, the potential energy surfaces of even-even actinide nuclei were investigated and the effect of triaxiality on the fission barriers in these nuclei was discussed. The nonaxial reflection-asymmetric beta(32) shape in some transfermium nuclei with N = 150, namely Cm-246, Cf-248, Fm-250 and No-252, were also studied.
118033922
A quantum oscillator model for entropic gravity
In Verlinde's theory of entropic gravity, the internal degrees of freedom are marked by "bits", but the microscopic origin of "bits" is unknown hitherto. To this direction, we adopt the quantum harmonic oscillators to naively model the internal degrees of freedom. In this model, the equipartition relation is modified at the low temperature. The Newton's law and Poisson's equation of gravity are reproduced at small distances, but they receive appreciable corrections at large distances. Geometrization of gravity for this model is explored, resulting in modifications to Einstein equations.
43842936
Study of the Energy Modulated Electron Cyclotron Resonance Ion Source for the Coupled RFQ-SFRFQ Cavity
The coupled RFQ and SFRFQ cavity has been manufactured and tested recently. According to the beam dynamic design, the input He beam within 120° phase width is designed for the cavity to achieve over 98% transmission efficiency. An energy modulated electron cyclotron resonance (ECR) ion source was proposed and simulated. To achieve the 1% energy modulation on the 30keV direct current (DC) beam, two simplified RF power feeding structures for beam bunching were studied. The simulations show positive results as well as the bunched beam is achieved by the energy modulated ECR ion source.