共查询到20条相似文献,搜索用时 217 毫秒
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本文利用超Poincare张量运算,构造了一个3维N=1超引力理论,给出了一般的拉氏密度,详细讨论了超对称自发破缺机制及超Higgs效应. 相似文献
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对称性与对称的破缺性 总被引:1,自引:0,他引:1
对称与对称破缺是自然界中普遍存在着的一种矛盾关系。对称是变化中的同一 ,反映不同物质形态在运动中的共性 ,破缺是变化中的差异 ,反映不同物质形态在运动中各自的特性。自然界的物质 (包括整个自然界在内 )处于对称→对称破缺→深一级对称→对称性又破缺……这样不断深化之中 相似文献
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在对称破缺Hartree近似下讨论了由Hubbard模型描述的金属超晶格。研究了由磁性金属层和非磁金属层组成的超晶格基态的反铁磁性。 相似文献
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If supersymmetry (SUSY) will be discovered, successful models of flavour not only have to provide an explanation of the flavour structure of the Standard Model fermions, but also of the flavour structure of their scalar superpartners. We discuss aspects of such “SUSY flavour” models, towards predicting both flavour structures, in the context of supergravity (SUGRA). We point out the importance of carefully taking into account SUSY-specific effects, such as 1-loop SUSY threshold corrections and canonical normalisation, when fitting the model to the data for fermion masses and mixings. This entangles the flavour model with the SUSY parameters and leads to interesting predictions for the sparticle spectrum. We demonstrate these effects by analyzing an example class of flavour models in the framework of an SU(5) Grand Unified Theory with a family symmetry with real triplet representations. For flavour violation through the SUSY soft breaking terms, the class of models realises a scheme we refer to as “Trilinear Dominance”, where flavour violation effects are dominantly induced by the trilinear terms. 相似文献
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R-symmetries, which are needed for supersymmetry (SUSY) breaking in O’Raifeartaigh models, often lead to SUSY runaway directions trough a complexified R-transformation. Non-R symmetries also lead to runaway directions in a similar way. This work investigates the occurrence of runaway directions of both SUSY and SUSY breaking types. We clarify previous issues on fractional charges and genericness, and make a refined statement on conditions for runaway directions related to either R-symmetries or non-R symmetries. We present a generic and anomaly-free model to show the existence of runaway directions related to non-R symmetries. We also comment on the possibility to combine the non-R symmetry case to the R-symmetry case by an R-charge redefinition. 相似文献
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Abazov VM Abbott B Abolins M Acharya BS Adams DL Adams M Adams T Agelou M Agram JL Ahmed SN Ahn SH Alexeev GD Alkhazov G Alton A Alverson G Alves GA Anderson S Andrieu B Arnoud Y Askew A Asman B Atramentov O Autermann C Avila C Babukhadia L Bacon TC Baden A Baffioni S Baldin B Balm PW Banerjee S Barberis E Bargassa P Baringer P Barnes C Barreto J Bartlett JF Bassler U Bauer D Bean A Beauceron S Beaudette F Begel M Bellavance A Beri SB Bernardi G Bernhard R Bertram I Besançon M Besson A 《Physical review letters》2005,94(4):041801
We report the results of a search for supersymmetry (SUSY) with gauge-mediated breaking in the missing transverse energy distribution of inclusive diphoton events using 263 pb(-1) of data collected by the D0 experiment at the Fermilab Tevatron Collider in 2002-2004. No excess is observed above the background expected from standard model processes, and lower limits on the masses of the lightest neutralino and chargino of about 108 and 195 GeV, respectively, are set at the 95% confidence level. These are the most stringent limits to date for models with gauge-mediated SUSY breaking with a short-lived neutralino as the next-to-lightest SUSY particle. 相似文献
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A bilinear R-parity breaking SUSY model for neutrino mass and mixing predicts the lightest superparticle to decay mainly into a pair of tau leptons or b quarks along with a neutrino for relatively light SUSY spectra. This leads to a distinctive triple bang signature of SUSY events at ultrahigh energy neutrino telescopes like IceCube or Antares. While the expected signal size is only marginal at IceCube, it will be promising for a future multi-km3 size neutrino telescope. 相似文献
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We consider the phenomenology of a class of gauge-mediated supersymmetry (SUSY) breaking (GMSB) models at a Linear Collider (LC) with up to 500 GeV. In particular, we refer to a high-luminosity ( cm s) machine, and use detailed simulation tools for a proposed detector. Among the GMSB-model building options, we define a simple
framework and outline its predictions at the LC, under the assumption that no SUSY signal is detected at LEP or Tevatron.
We assess the potential of the LC to distinguish between the various SUSY model options and to measure the underlying parameters
with high precision, including for those scenarios where a clear SUSY signal would have already been detected at the LHC before
starting the LC operations. Our focus is on the case where a neutralino () is the next-to-lightest SUSY particle (NLSP), for which we determine the relevant regions of the GMSB parameter space. Many
observables are calculated and discussed, including production cross sections, NLSP decay widths, branching ratios and distributions,
for dominant and rare channels. We sketch how to extract the messenger and electroweak scale model parameters from a spectrum
measured via, e.g. threshold-scanning techniques. Several experimental methods to measure the NLSP mass and lifetime are proposed
and simulated in detail. We show that these methods can cover most of the lifetime range allowed by perturbativity requirements
and suggested by cosmology in GMSB models. Also, they are relevant for any general low-energy SUSY breaking scenario. Values
of as short as 10's of m and as long as 10's of m can be measured with errors at the level of 10% or better after one year of LC running with high
luminosity. We discuss how to determine a narrow range () for the fundamental SUSY breaking scale , based on the measured , . Finally, we suggest how to optimise the LC detector performance for this purpose.
Received: 19 May 1999 / Published online: 8 December 1999 相似文献
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We point out that the strong-CP problem becomes even more pressing in the context of weak models where CP violation originates in the Higgs sector. θ renormalization is numerically too large at the one-loop level and even divergent at the two-loop level. When supersymmetry (SUSY) is introduced, many more possible sources for CP violation open up. θ renormalization could stay finite in perturbation theory, however, we find that the one-loop result turns out to be too large by orders of magnitude unless SUSY fields like gauginos and higgsinos are highly degenerate in mass or SUSY breaking proceeds in a very special way, or a Peccei-Quinn symmetry holds leading to superlight axions. 相似文献
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Taekoon Lee 《The European Physical Journal C - Particles and Fields》2000,13(2):365-369
The goldstino–matter interactions given by the Goldberger–Treiman relations can receive higher dimensional operator corrections
of , where M denotes the mass of the mediators through which SUSY breaking is transmitted. These corrections in the gauge mediated SUSY
breaking models arise from loop diagrams, and an explicit calculation of such corrections is presented. It is emphasized that
the Goldberger–Treiman vertices are valid only below the mediator scale, and at higher energies goldstinos decouple from the
MSSM fields. The implication of this fact for gravitino cosmology in GMSB models is mentioned.
Received: 22 December 1998 / Revised version: 1 July 1999 / Published online: 17 February 2000 相似文献
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Youichi Yamada 《Zeitschrift fur Physik C Particles and Fields》1993,60(1):83-93
We study consequences of the threshold effects of supersymmetric (SUSY) and superheavy (GUT) particles to the gauge coupling unification condition in two specific supersymmetricSU(5) models, the minimal model and the missing doublet model with natural doublet-triplet splitting. We present a consistent treatment of theSU(2)×U(1) breaking mass terms in the SUSY particle threshold effects, as well as that of the top quark threshold effect, which have been ignored in previous works. The GUT threshold effects are constrained by the proton decay experiments and by some theoretical consistency conditions, but they are strongly model dependent. For example, under a certain assumption for the SUSY particle masses, the minimal model favors a large (>1 TeV) SUSY breaking scale or a high s(m
z
)(<0.12), whereas=" the=" missing=" doublet=" model=" allows=" a=" low=">0.12),><1 tev)=" susy=" breaking=" scale=" for=" 0.11=">s(m
z
)>0.13. The consequences of these two models in the proton decay experiments are also briefly discussed.1> 相似文献
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We revisit the monophoton plus missing energy signature at \(e^+e^-\) colliders in supersymmetric (SUSY) models where the gravitino is very light. There are two possible processes which provide the signal: gravitino pair production and associated gravitino production with a neutralino, leading the monophoton final state via an additional photon radiation and via the neutralino decay, respectively. By using the superspace formalism, we construct a model that allows us to study the parameter space for the both processes. We show that the signal cross section and the photon spectra provide information on the masses of the SUSY particles as well as the SUSY breaking scale. 相似文献
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In the previous work, it was shown that, in supersymmetric (matrix) discretized quantum mechanics, inclusion of an external field twisting the boundary condition of fermions enables us to discuss spontaneous breaking of supersymmetry (SUSY) in the path-integral formalism in a well-defined way. In the present work, we continue investigating the same systems from the points of view of localization and Nicolai mapping. The localization is studied by changing of integration variables in the path integral, which is applicable whether or not SUSY is explicitly broken. We examine in detail how the integrand of the partition function with respect to the integral over the auxiliary field behaves as the auxiliary field vanishes, which clarifies a mechanism of the localization. In SUSY matrix models, we obtain a matrix-model generalization of the localization formula. In terms of eigenvalues of matrix variables, we observe that eigenvalues' dynamics is governed by balance of attractive force from the localization and repulsive force from the Vandermonde determinant. The approach of the Nicolai mapping works even in the presence of the external field. It enables us to compute the partition function of SUSY matrix models for finite N (N is the rank of matrices) with arbitrary superpotential at least in the leading nontrivial order of an expansion with respect to the small external field. We confirm the restoration of SUSY in the large-N limit of a SUSY matrix model with a double-well scalar potential observed in the previous work. 相似文献