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1.
在TC2模型框架下研究了强子对撞机Tevatron和LHC上中性top-pion介子Π0t的产生过程pp(pp)→Π0tΠ0t和pp(pp)→bΠ0t. 研究结果表明, 在Tevatron上, 这两个过程的产生截面都很小, 通过这两个过程我们无法探测到中性top-pion介子. 在LHC上, 产生截面会大大增加, 但通过Π0tΠ0t的产生仍无法探测到中性top-pion介子. bΠ0t在LHC上的产生截面能达到几百个fb甚至pb的量级, LHC每年能产生104—105个bΠ0t事例. 另外, 味改变耦合Π0t tc的存在, 使得实验能通过背景非常干净的衰变道Π0t→tc来探测Π0t. 因此, 通过bΠ0t这一产生机制, 未来的LHC实验应能获得足够多的可鉴别的Π0t事例. 我们的研究结果, 可为LHC上寻找中性top-pions介子检验TC2模型提供有价值的理论指导. 相似文献
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在TC2模型框架下研究了强子对撞机Tevatron和LHC上中性top-pion介子∏0t的产生过程pp(p-p)→∏0t∏0t和pp(p-p)→b∏0t.研究结果表明,在Tevatron上,这两个过程的产生截面都很小,通过这两个过程我们无法探测到中性top-pion介子.在LHC上,产生截面会大大增加,但通过∏0t∏0t的产生仍无法探测到中性top-pion介子.b∏0t在LHC上的产生截面能达到几百个fb甚至pb的量级,LHC每年能产生104-105个b∏0t事例.另外,味改变耦合∏0tt-c的存在,使得实验能通过背景非常干净的衰变道∏0t→t-c来探测∏0t.因此,通过b∏0t这一产生机制,未来的LHC实验应能获得足够多的可鉴别的∏0t事例.我们的研究结果,可为LHC上寻找中性top-pions介子检验TC2模型提供有价值的理论指导. 相似文献
3.
通过味改变过程探测TC2理论中的中性toppion介子 总被引:1,自引:0,他引:1
在Topcolor辅助的Technicolor(TC2)模型下,研究了一个产生中性toppion介子(Π0t)的味改变过程:e+e–→tcΠ0t.研究结果表明,在TESLA对撞机上,当质心能量高时,在大多数参数区间,e+e–→tcΠ0t的产生截面可达到0.1fb量级,每年可有数十个Π0t介子事例产生.当Π0t质量较小时,由于共振效应,产生截面可达几个fb.由于背景干净,有可能在TESLA对撞机上探测到Π0t介子事例.另一方面,研究发现,可以在实验中清晰地探测到toppion-charm不变质量分布中的共振峰.因此,Π0t介子的产生过程e+e–→tcΠ0t为人们提供了一个极好的机会,来探测中性Π0t介子,从而检验TC2模型. 相似文献
4.
In the framework of the topcolor-assisted technicolor (TC2) model, we study the production of the neutral top-pion πt^0 in association with a high-pw jet at the LHC, which proceeds via the partonic processes gg→πt^0g, gq →πt^0q, qq→πt^0g, gb(b)→πt^0b(b), and bb→πt^0g. We find that it is very challenging to detect the neutral top-pion πt^0 via the process pp → πt^0 +jet + X+ tt+jet +X, while the possible signatures of πt^0 might be detected via the process pp→πt^0 +jet + X→(tc+tc)+jet+X at the LHC. 相似文献
5.
在TC2理论框架下,计算了在高能正负电子对撞机(LC)上,TC2动力学对味改变中性流过程e+e-→tc产生截面的修正和TC2理论预言的中性top–pionπ0t对该过程产生截面的贡献.计算结果表明:TC2理论对LC实验中tc夸克联合产生的贡献主要来自中性top-pion π0t.在TC2理论的绝大部分参数空间内,可达10-2ph.若假设LC的积分亮度为500fb-1,则每年可产生数千个tc事例.因此,将来的LC实验可作为检验TC2理论的重要工具. 相似文献
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精确计算p重整化链图传播下p→2π~0反应微分截面(英文) 总被引:1,自引:1,他引:0
采用中性介子π0与核子N-反核子N-强相互作用的Lorentz不变耦合模型,对质子反质子重整化链图传播下p→2π0反应微分截面作了严格解析计算,获得精确理论结果;并通过将该计算结果与质子反质子树图和重整化单圈图传播下p→2π0反应微分截面作对比分析,讨论了相关辐射修正.此研究结果对于Lorentz不变耦合模型理论的深入研究与核物理的深入探索,都将提供理论计算研究方面一定的学术参考价值. 相似文献
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本文基于第一性原理的密度泛函理论(DFT)和密度泛函微扰理论(DFPT)方法,利用虚晶近似的计算方法研究了Pb-Sn合金的晶格结构、电子能带、声子能带及热力学性质,并用晶格能量差可与达到熔化温度时的振动能量相当的固-液相变机理研究了熔化温度,同时与所计算Pb的所有结果进行了对比. 相似文献
13.
Summary In the field of the exploration of the Solar System NASA and ESA have jointly planned two cornerstone missions whose aim is
the close observation of two largely unknown planetary bodies: Titan (Cassini mission) and comet nuclei (Rosetta mission).
Our attention in this paper will be devoted to the first one, however some results of this study can be applied also to the
second one. Titan is one of Saturn's moons and is characterized by the presence of a dense atmosphere, opaque for optical
sensors. Therefore radar data are the only ones at least theoretically capable of giving relatively detailed informations
about the geomorphologic structure of Titan. As a matter of fact the radar cross-section depends on both the dielectric constant
of the target by means of the Fresnel reflectivity and on its surface roughness. Moreover if the attenuation is sufficiently
low, the radar in principle could be able to detect subsurface discontinuities as well. The above considerations hold true
only if a well-suited analytical model accounting for surface backscattering is known. All throughout this paper the radar
cross-section of planetary bodies will be evaluated in the case of high-resolution radars.
Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990. 相似文献
14.
V. Formisano G. Bellucci A. Grigoriev A. Coradini J. P. Bibring 《Il Nuovo Cimento C》1992,15(6):1113-1119
Summary Multispectral imaging of planets opens a new class of studies of atmospheric and surface signatures. With ISM experiment on
board Phobos, the first IR multispectral imaging of Mars from space was achieved. In viem of the Future Omega experiment on
board Mars 94, we present here a sample of data and results (and problems) which can be achieved by studying spectral reflectance.
Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990. 相似文献
15.
Physical modeling of direct current and radio frequency characteristics for In P-based InAlAs/InGaAs HEMTs 下载免费PDF全文
Direct current(DC) and radio frequency(RF) performances of InP-based high electron mobility transistors(HEMTs)are investigated by Sentaurus TCAD. The physical models including hydrodynamic transport model, Shockley–Read–Hall recombination, Auger recombination, radiative recombination, density gradient model and high field-dependent mobility are used to characterize the devices. The simulated results and measured results about DC and RF performances are compared, showing that they are well matched. However, the slight differences in channel current and pinch-off voltage may be accounted for by the surface defects resulting from oxidized InAlAs material in the gate-recess region. Moreover,the simulated frequency characteristics can be extrapolated beyond the test equipment limitation of 40 GHz, which gives a more accurate maximum oscillation frequency( f_(max)) of 385 GHz. 相似文献
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V. Formisano V. Moroz E. Amata P. Baldetti G. Bellucci G. Chionchio A. Matteuzzi R. Orfei G. Piccioni A. Carusi et al. 《Il Nuovo Cimento C》1993,16(5):575-588
Summary PFS is a two-channel Fourier spectrometer operating in the infra-red wavelengths between 1.25 and 45 μm. The instrument will
be used mainly in the study of the Martian atmosphere. The principal goals are the measurements of the atmospheric temperature
and pressure, atmospheric constituents, aerosol and clouds, ground pressure for surface topography, optical and thermophysics
properties of the Martian soil. PFS will fly on the Mars 94 spacecraft which should be launched in 1994 and reach the planet
in 1995. It is essentially constituted by two different interferometers located in the same box which is divided into two
parts. A dichroic placed on the PFS entrance is used to separate the spectral range into two parts, a division needed by the
different optical materials which have to be used in each spectral range. The optical layout of the experiment is very compact.
Each channel uses two cubic mirrors mounted on an L-structure pivoted on a motor. The motor moves the mechanics and permits
the optical-path difference between the arms to be varied. Each interformeter operates in a different spectral range, respectively,
between (1.25÷4.8) μm (8000÷2083cm−1) and (6÷45)μm (1666÷220)cm−1). The spectral resolution is 2 cm−1. The entrance aperture area is 30 cm2 per channel and the field of view is 2 and 4 degrees. Every measurement lasts about 4 s. The time and, therefore, the relative
optical-path difference for the measurement of every point of the interferogram is given by the zero crossings of the interferogram
of a reference monochromatic channel at 1.2 μm which uses a laser diode as source. The two interferograms are double-sided
and will have 16384 and 4096 points, respectively, corresponding to spectra of 6250 and 1823 useful points.
Paper presented at the 6th Cosmic Physics National Conference, Palermo, 3–7 November 1992. 相似文献
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B. Pernice 《Il Nuovo Cimento C》1992,15(6):1133-1136
Summary The updated status of the cooperation between NASA and ASI on the Cassini mission is here presented. This outstanding scientific
mission is devoted to study the Saturnian system with a NASA orbiter and a ESA probe. The Italian involvement, managed by
the Agenzia Spaziale Italiana (ASI), concerns the design and development of important Cassini Orbiter subsystems. Promotion
of the Italian science community's interests and of the national industry's technological capabilities are the rationales
for the cooperation.
This is an updated version of the contribution presented at San Miniato. 相似文献
18.
J. F. Ye H. Chen R. Note H. Mizuseki Y. Kawazoe 《Journal of Physical Organic Chemistry》2008,21(9):789-796
This paper presents theoretical predictions for the excess polarizabilities upon excitation from the ground state to the first dipole‐allowed excited state (11Bu) of some conjugated oligomers. The excess polarizability was obtained by simulating the Stark shift, which was predicted by the time‐dependent density functional theory (TDDFT) with the hybrid Becke‐3 Lee–Yang–Parr (B3LYP) potential. The Stark shift in solution was simulated by employing the non‐equilibrium integral equation formalism polarizable continuum model (IEFPCM). All the model molecules considered in this study were fully optimized by the Hartree–Fock (HF) method and the density functional theory (DFT) with the B3LYP potential, respectively. For diphenylpolyenes, the excess polarizabilities displayed by the DFT/B3LYP‐optimized geometries are more reasonable than those displayed by the HF‐optimized geometries when compared with the experimental results. However, this feature is not clearly demonstrated by our results in the cases of oligo(phenylenevinylene)s (OPVs). Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
19.
The solution of the time-dependent Fokker-Planck equation of non-degenerate optical parametric amplification and its application to the optimum realization of EPR paradox 下载免费PDF全文
In this paper, the solution of the time-dependent Fokker-Planck equation of non-degenerate optical parametric amplification is used to deduce the condition demonstrating the Einstein-Podolsky-Rosen (EPR) paradox. The analytics and numerical calculation show the influence of pump depletion on the error in the measurement of continuous variables. The optimum realization of EPR paradox can be achieved by adjusting the parameter of squeezing. This result is of practical importance when the realistic experimental conditions are taken into consideration . 相似文献
20.
Xilin Peng Paul Kolbo Konstantin Nikolaev Shawn Chen Zhongyan Wang Tom Boonstra Paul Anderson Steven Kalderon Peter Czoschke Augusto Morrone Dimitar Dimtrov Song Xue Yonghua Chen 《Journal of magnetism and magnetic materials》2009,321(12):1889-1892
Current-perpendicular-to the plane (CPP) giant magnetoresistive (GMR) sensors with a current-confined-path (CCP) layer inserted within the Cu spacer have been manufactured using ultrahigh vacuum PVD sputtering, photolithography, and ion milling processes. Compared with a pure metallic CPP system, the CCP insertion layer enables a substantial increase in sensor resistance with an equivalent or better GMR ratio, and thus a significant improvement in the ΔRA amplitude. Heads with such a sensor have been tested under various bias currents, both quasistatically and on a spinstand. It was found that the resistance of the sensors increases with increasing bias current and voltage, following typical metallic behavior. Also, the CCP insertion layer enables operation at higher bias currents compared with the pure metallic sensors (without the insertion layer) and thus a higher output signal. This effect is attributed to less magnetic instability due to the reduced Ampere fields around the narrow (∼6 nm) current-confined paths. Finally, the CPP-GMR heads with CCP layer were tested under high-density recording conditions using the perpendicular recording media. Bit error rate (BER) as a function of linear density is reported. Microtrack profiles were also recorded to determine track density capability. 相似文献