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排序方式: 共有228条查询结果,搜索用时 93 毫秒
41.
We briefly survey several typical CP-conserving two-Higgs-doublet models (2HDMs) in light of current experiments. First we derive the masses and couplings of the mass eigenstates from the Lagrangians. Then we analyze the constraints from theory and oblique electroweak parameters. Finally, we delineate the status of 2HDM in light of the LHC searches, the dark matter detections and the muon g − 2 measurement. 相似文献
42.
W. A. Perkins 《International Journal of Theoretical Physics》2008,47(5):1316-1321
Long ago an unexpected and unexplainable phenomena was observed. The distribution of muons from positive pion decay at rest
was anisotropic with an excess in the backward direction relative to the direction of the proton beam from which it was produced.
Although this effect was observed by several different groups with pions produced by different means and detected by different
methods, the result was not accepted by the physics community, because it is in direct conflict with a large set of other
experiments indicating that the pion is a pseudoscalar particle. It is possible to satisfy both sets of experiments if helicity-zero
vector particles exist and the pion is such a particle. Helicity-zero vector particles have direction but no net spin. For
the neutral pion to be a vector particle requires an additional modification to conventional theory as discussed herein. An
experiment is proposed which can prove that the asymmetry in the distribution of muons from pion decay is a genuine physical
effect because the asymmetry can be modified in a controllable manner. A positive result will also prove that the pion is
not a pseudoscalar particle. 相似文献
43.
M. Gaelens J. Andrzejewski J. Camps P. Decrock M. Huyse K. Kruglov W.F. Mueller A. Piechaczek N. Severijns J. Szerypo G. Vancraeynest P. Van Duppen J. Wauters 《The European Physical Journal A - Hadrons and Nuclei》2001,11(4):413-420
A high-precision measurement of the 14O half-life has been performed using a mass-separated radioactive beam in combination with a germanium detector set-up. This
is the first 14O half-life measurement with a contamination-free source. The final result of 70.560 ± 0.049 seconds is in agreement with
the generally adopted mean value.
Received: 5 April 2001 / Accepted: 6 August 2001 相似文献
44.
B. Lee Roberts 《中国物理 C》2010,34(6):741-744
The New Muon (g-2) Collaboration at Fermilab has proposed to measure the anomalous magnetic moment of the muon, αμ, a factor of four better than was done in E821 at the Brookhaven AGS, which obtained αμ = [116592089(63)] × 10^-11 ±0.54 ppm. The last digit of a, is changed from the published value owing to a new value of the ratio of the muon-to-proton magnetic moment that has become available. At present there appears to be a difference between the Standard-Model value and the measured value, at the ≌ 3 standard deviation level when electron-positron annihilation data are used to determine the lowest-order hadronic piece of the Standard Model contribution. The improved experiment, along with further advances in the determination of the hadronic contribution, should clarify this difference. Because of its ability to constrain the interpretation of discoveries made at the LHC, the improved measurement will be of significant value, whatever discoveries may come from the LHC. 相似文献
45.
Calculation of equilibrium composition and establishing time in a mixture of three hydrogen isotopes
N.S. Ganchuk A.N. Golubkov D.A. Kreknin L.I. Ponomarev A.A. Selezenev A.A. Yukhimchuk 《Hyperfine Interactions》1999,119(1-4):357-360
A mathematical model describing the kinetics of establishing equilibrium is developed. Equilibrium concentrations of isotopic
molecules for gas mixtures used in muon catalyzed fusion research are calculated.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
46.
In this article, we describe how we are applying the methods of chemically reactive scattering to the key resonant reaction
in muon catalysed fusion. Preliminary results are presented for cross-sections.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
47.
H. V. Klapdor-Kleingrothaus H. Päs U. Sarkar 《The European Physical Journal A - Hadrons and Nuclei》2000,8(4):577-580
We discuss violations of CPT and quantum mechanics due to interactions of neutrinos with space-time quantum foam. Neutrinoless
double beta decay and oscillations of neutrinos from astrophysical sources (supernovae, active galactic nuclei) are analysed.
It is found that the propagation distance is the crucial quantity entering any bounds on EHNS parameters. Thus, while the
bounds from neutrinoless double beta decay are not significant, the data of the supernova 1987a imply a bound being several
orders of magnitude more stringent than the ones known from the literature. Even more stringent limits may be obtained from
the investigation of neutrino oscillations from active galactic nuclei sources, which have an impressive potential for the
search of quantum foam interactions in the neutrino sector.
Received: 5 June 2000 / Accepted: 12 July 2000 相似文献
48.
The new project GENIUS will cover a wide range of the parameter space of predictions of SUSY for neutralinos as cold dark matter. Further it has the potential to be a real-time detector for low-energy (pp and 7Be) solar neutrinos. A GENIUS Test Facility has been funded and will come into operation by early 2003. 相似文献
49.
I. Petermann G. Martınez-Pinedo K. Langanke E. Caurier 《The European Physical Journal A - Hadrons and Nuclei》2007,34(3):319-324
We have performed large-scale shell model calculations of the Gamow-Teller strength distributions in N ∼ Z
pf -shell nuclei. These calculations were motivated by the experimental attempts to measure the low-lying GT strength for the
even-even N = Z + 2 or N = Z - 2 nuclei 46Ti , 50Cr , 54Fe and 62Ge , where a sizable low-energy GT strength could be interpreted as reminiscence of SU(4) symmetry; in the limit of exact SU(4) symmetry the GT- strength would be concentrated in a single transition to the lowest T = 0, J = 1+ state in the daughter. We confirm that the SU(4) symmetry is strongly broken by the spin-orbit interaction and by increasing neutron excess. 相似文献
50.
M. Asai M. Sakama K. Tsukada S. Ichikawa H. Haba I. Nishinaka Y. Nagame S. Goto Y. Kojima Y. Oura H. Nakahara M. Shibata K. Kawade 《The European Physical Journal A - Hadrons and Nuclei》2004,22(3):411-416
EC and decays of 235Am have been studied using a gas-jet coupled on-line isotope separator. Excited states in 235Pu have been established for the first time by means of -ray spectroscopy following the EC decay of 235Am. The deduced log ft value suggests that the ground state of 235Am should have the 5/2-[523] configuration. The - coincidence result has revealed that the 5/2-[523] state in 231Np populated by the favored transition of 235Am is located at < 15 keV, which allows us to precisely determine the Q value of 235Am. 相似文献