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排序方式: 共有399条查询结果,搜索用时 15 毫秒
101.
102.
M. Hesse M. Bernas P. Armbruster T. Aumann S. Czajkowski Ph. Dessagne C. Donzaud H. Geissel E. Hanelt A. Heinz C. Kozhuharov Ch. Miehé G. Münzenberg M. Pfützner C. Röhl K. -H. Schmidt W. Schwab C. Stéphan K. Sümmerer L. Tassan-Got 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):69-75
Charge-loss and fission cross-sections of238U at 750 A·MeV were measured on Al, Cu and Pb targets. The charge-loss rate was obtained by the attenuation method. Fission was selected by detecting the pair of highly ionizing fragments. Since the neutron-loss cross sections were measured in a parallel experiment for the same projectiles, all cross sections contributing to238U collisions on nuclei are available now as function of the target mass number and can be compared with current models. 相似文献
103.
104.
The measured B-->pipi,piK branching ratios (BRs) exhibit puzzling patterns. We point out that the B-->pipi hierarchy can be nicely accommodated in the standard model (SM) through nonfactorizable hadronic interference effects, whereas the B-->piK system may indicate new physics (NP) in the electroweak (EW) penguin sector. Using the B-->pipi data and the SU(3) flavor symmetry, we fix the hadronic B-->piK parameters and show that any currently observed feature of the B-->piK system can be easily explained through enhanced EW penguin diagrams with a large CP-violating NP phase. This in turn implies in particular an enhancement of the K(L)-->pi(0)nunu rate by 1 order of magnitude, with BR(K(L)-->pi(0)nunu) approximately 4BR(K+-->pi(+)nunu), BR(K(L)-->pi(0)e(+)e(-))=O(10(-10)), and (sin(2beta)(pinunu)<0. We address also other rare K and B decays and B(d)-->phiK(S). 相似文献
105.
A. J. Buras R. Fleischer S. Recksiegel F. Schwab 《The European Physical Journal C - Particles and Fields》2003,32(1):45-54
The standard-model interpretation of the ratios of charged and neutral
rates, R
c and R
n, respectively, points towards a puzzling picture. Since these observables are affected significantly by colour-allowed electroweak (EW) penguins, this
puzzle could be a manifestation of new physics in the EW penguin sector. Performing the analysis in the R
n- R
c plane, which is very suitable for monitoring various effects, we demonstrate that we may, in fact, move straightforwardly to the experimental region in this plane through an enhancement of the relevant EW penguin parameter q. We derive analytical bounds for q in terms of a quantity L, which measures the violation of the Lipkin sum rule, and point out that strong phases around
are favoured by the data, in contrast to QCD factorisation. The
modes imply a correlation between q and the angle
that, in the limit of negligible rescattering effects and colour-suppressed EW penguins, depends only on the value of L. Concentrating on a minimal flavour-violating new-physics scenario with enhanced Z
0 penguins, we find that the current experimental values on
require roughly
. As the
data give
, L has either to move to smaller values once the
data improve or new sources of flavour and CP violation are needed. In turn, the enhanced values of L seen in the
data could be accompanied by enhanced branching ratios for the rare decays
,
,
and
. Most interesting turns out to be the correlation between the
modes and
, with the latter depending approximately on a single scaling variable
.Received: 8 September 2003, Published online: 12 November 2003 相似文献
106.
Recent experimental results on hadronic tau decays into strange particles by the OPAL Collaboration are employed to determine V(us) and m(s) from moments of the invariant mass distribution. Our results are V(us)=0.2208+/-0.0034 and m(s)(2 GeV)=81+/-22 MeV. The error on V(us) is dominated by experiment and should be improvable in the future. Nevertheless, already now our result is competitive with the standard extraction of V(us) from K(e3) decays, and it is compatible with unitarity. 相似文献
107.
We have directly time resolved the lattice motions associated with the formation of the self-trapped exciton in the quasi-one-dimensional system [Pt(en)(2)] [Pt(en)2Br2];(PF6)(4) ( en = ethylene-diamine, C2H8N2), using femtosecond impulsive excitation techniques. A strongly damped, low-frequency wave packet modulation at approximately 110 cm(-1) accompanies the formation of the self-trapped exciton on a approximately 200 fs time scale following excitation of the intervalence charge-transfer transition. Coherent oscillations at the ground state vibrational frequency and its harmonics are also detected. 相似文献
108.
R. Schwab 《Fresenius' Journal of Analytical Chemistry》1968,243(1):208-209
Ohne Zusammenfassung 相似文献
109.
110.