共查询到20条相似文献,搜索用时 187 毫秒
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在顶色辅助的人工色模型下计算了高能e+e-对撞机上top介子辅助的b夸克对产生过程e+e-→bbπ0t的产生截面.发现在一定的参数范围内,这个过程的产生截面大于10fb,比标准模型下标量Higgs粒子辅助的b夸克对产生过程大许多,与最小超对称模型下标量和赝标量Higgs粒子h0,H0,A0的相应产生截面大致相当.人工色理论的信息可能在下一代正负电子对撞实验中探测到. 相似文献
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在高能e+e-碰撞实验(LC)中,研究了顶色辅助的人工色(TC2)理论所预言的中性top介子 的产生. 结果表明,在LC实验中通过过程e+e-→tc, e+e-→γtc和e+e-→Ztc可以探测到πt0的物理迹象. 相似文献
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在一代Technicolor(TC)模型中计算了PGBs(PseudoGoldenstoneBosons)对高能e+e-→tt过程的单圈量子效应.给出了重整化的形状因子和矩阵元.计算了PGBs对总截面前后不对称参数AFB和左右不对称参数ALR的虚贡献,结果表明选取适当的参数值,新物理对以上可测量的贡献最大分别可达:-12.3%、-3.3%和-11.7%.在下一代对撞机上这一理论结果能为TC理论打开实验的窗口.同样的计算表明PGBs对e+e-→bb过程的单圈贡献小于-1.0%. 相似文献
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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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用推广的矩分析方法讨论了过程J/ψ→X+f0(980),X→K+K-,f0(980)→π+π-.利用得到的矩表达式,可以确定玻色共振态X的自旋-宇称. 相似文献
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The contributions of two-photon exchange in the process e~+ + e~-→p +(p) including N and △ intermediate states are estimated in a simple hadronic model. The corrections to the unpolarized cross section as well as to the polarized observables P_x and P_z are evaluated. The results show the corrections to unpolarized cross section are small and the angle dependence becomes weak at small s after considering the N and △(1232) contributions simultaneously, while the correction to P_z is enhanced. 相似文献
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In the context of topcolor-assisted technicolor (TC2) model, we study the charged and neutral top-pions production process γγ→W+ Πt-Πt0. We find that the production cross section is larger than that of the process γγ→W+H-H in the minimal supersymmetric standard model. With reasonable values of the parameters in the TC2 model, the cross section can reach the level of a few fb. Furthermore, the flavor-changing (FC) decay mode Πt0 → t\bar{c} is the best channel to detect theneutral top-pion due to the clean SM background. With a large number of events and the clean background, the neutral top-pion should be observable at future linear colliders operating in γγ mode at the TeV energy scale. 相似文献
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In the framework of T2HDM, we calculated the new physics contributions involving neutral Higgs bosons to the branching ratios of B_(s,d)~0→e~+e~-(e=e,μ) decays. Comparing the theoretical predictions with the experimental upper-limits, we found that (a) The data of Br(B_d~0→e~+e~-)give the upper bound on tanβ: tanβ≤ 22, while Br(B_s~0→e~+e~-)give tanβ≤12 for fixed δ = 0°, m_H+=350 GeV, m_Ho = 160 GeV, m_Ho= 115 GeV and m_Ao=120 GeV; (b) A light neutral Higgs boson mass m_Ho (m_Ao) less than 50 GeV (120 GeV) is excluded by the data of branching ratios for B_(s,d)~0→e~+e~-(e=μ) decays with tanβ=10; (c) The bounds on m_(h~0) and tanβ, or m_(A~0) and tanβ are strongly correlated: a smaller (larger) tanβ means a lighter (heavier) neutral Higgs boson. 相似文献
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M.Sudot 《中国物理C(英文版)》2009,33(12)
The electromagnetic probe is an excellent tool to investigate the structure of the nucleon. The nearly 4π detector PANDA, will allow to make a precise determination of the electromagnetic form factors of the proton in the time-like region with unprecedented precision. In the one-photon exchange approximation, the center of mass unpolarized differential cross section of the reaction pp → e~+e~- is a linear combination of the squared moduli of the electric G_E and magnetic G_M proton form factors. The precise measurement of the angular distribution over almost full angular range then directly gives these quantities. At present only two experiments have provided the ratio R = |G_E|/|G_M| but with large statistical uncertainties. It is shown that with strict PID cuts and a kinematic fit, the dominant background, (p)p→π~+π~-, can be supressed to much less than 1% of the signal, without affecting the extraction of the ratio R. PANDA will therefore offer a unique opportunity to measure the ratio with a precision ranging from <1% at low q~2 up to 30 % for q~2 =14 (GeV/c)~2. 相似文献
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In the context of the top-color-assisted technicolor (TC2) model, the flavor-changing neutral-current (FCNC) interaction induced by the top-higgs (h0t) are predicted at tree level. We study the relevant processes of e+e-(γγ)→ t\bar{c}h0t at the International Linear Collider (ILC). It is found that these rare processes production rates can be enhanced significantly in the TC2 model. Especially for the process γγ → t\bar{c}h0t, the total cross section will reach a few fb in the reasonable parameter space. We also calculate the distributions of transverse momenta, pseudo-rapid and invariant mass of the top-higgs. In view of the main decay modes of top-higgs for mh0t<2mt, we find that there will be several hundreds FCNC events produced at the ILC with annuallyintegral luminosity of 500 fb-1. Due to the clean background, such FCNC signals can possibly be detected at the ILC. 相似文献
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HOU Hong-Sheng 《理论物理通讯》2009,52(6):1036-1040
We studied the charged top-pion in the topcolor assisted technicolor model (TC2). If the charged top-pions are heavy, mπt >mt+mb, they will decay mainly via the channel π+t → t \bar{b}. We also calculated the production ofcharged top-pion at the Tevatron and LHC. The cross section can reach to 100 fb at the Tevatron and dozens of pb at the LHC depending on the mass of the top-pion. 相似文献
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In the framework of the topcolor-assisted technicolor (TC2) model, we study the production of the neutral top-pion πt0 in association with a high-pT jet al the LHC, which proceeds via the partonic processes gg→πt0g, gq→πt0q, qq→πt0g, gb(b)→πt0b(b), and bb→πt0g. We find that it is very challenging to detect the neutral top-pion πt0 via the process pp→πt0 +jet-t-X→tt +jet + X, while the possible signatures of πt0 might be detected via the process pp→πt0 +jet+X→(tc+tc)+jet+X at the LHC. 相似文献
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LIU Yao-Bei SHEN Jie-Fen CUI Xiao-Min REN Xiao-Yan 《理论物理通讯》2008,49(5):1279-1282
The littlest Higgs (LH) model is the most economical one among various little Higgs models, which predicts the existence of the charged scalars Φ^±. In this paper, we study the production of the charged Higgs boson Φ^- with single top quark via the process gb →tΦ^- at the CERN Large Hadron Collider (LHC). The numerical results show that the production cross section is sma/ler than 0.2 pb in most of the parameters space, it is very difficult to observe the signatures of the charged scalars via the process pp → gb + X → tΦ^- + X at the LHC experiments. However, it can open a window to distinguish the top-pions in the TC2 model or charged Higgs in the MSSM from Φ^±. 相似文献
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S. Uehara 《中国物理C(英文版)》2008,32(6):499-503
We have measured the cross section for π+π- production in two-photon collisions using a data sample with an integrated luminosity of 85.9 fb-1 collected with the Belle detector. The f0(980) resonance is observed as a peak in the energy spectrum of the cross section. We also report preliminary results for γγ→π0π0 with two-photon center-of-mass energies ranging from 0.6 to 4.0 GeV, based on a 95 fb-1 data sample. We find at least four resonant structures including a peak from f0(980). In addition, there is evidence for Xc0 production. We also make a preliminary discussion of the angular dependence and cross section ratio of γγ→π+π- and γγ→π0π0. 相似文献
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We discuss the contributions of the top-Higgs ht^0 proedicted by topcolor-assisted technicolor (TC2) models to the process e^ e^-→vvtt.We find that the contributions are very large.For mht=400 GeV and ε=0.01,the production cross section of this process can reach 11.2fb,which may be detected in the future high energy e^ e^- collider experiments.The process e^ e^-→vvtt can be used to test experimentally the signal of TC2 models. 相似文献