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1.
The single charged top-pion production processes e+e-→t\bar{b}Πt- and e+e-→ W+Πt- are studied in the framework of top-color-assisted technicolor (TC2) model. Our studies show that the cross section σ(e+e-→t\bar{b}Πt-) reaches the level of tens of fb and σ(e+e-→W+Πt-) reaches the level of a few fb. With the yearly integrated luminosity of L~500 fb-1 expected at the planned colliders, one could collect thousands of charged top-pion of events via the process e+e-→t\bar{b}Πt- and hundreds of events via the process e+e-→W+Πt-. The flavor changing decay mode Πt-→b\bar{c} is the best channel to detect charged top-pion due to the clean SM background. With a large number of events and the clean background, the charged top-pion should be observable at the planned colliders. Therefore, our studies in this paper can help us to search for charged top-pion, and furthermore, to test the TC2 model.  相似文献   

2.
A possible mechanism for the GSI e+e- narrow resonances as being due to non-perturbative effects of conventional QED is proposed. An application of the quasi-potential approach discloses a set of new resonances in a system of two charged particles. Numerical calculations agree with data on e+e- and pp narrow resonances. Additional new resonances are predicted for e+e-, pp, e-e- systems.  相似文献   

3.
In this paper,we investigate the production of a pair of doubly charged leptons associated with a gauge boson V(γ or Z) at future linear colliders via e~+e~-and γγ collisions.The numerical results show that the possible signals of the doubly charged leptons may be detected via the processes e~+e~→VX~(++)X~(--)and γγ→VX~(++)X~(--)at future ILC or CLIC experiments.  相似文献   

4.
目前,正负电子湮灭过程的核子激发态N*产生的实验数据主要来自于粲偶素能区。粲偶素衰变到核子激发态过程类似于其类时电磁形状因子测量过程,正反粲夸克短程湮灭提供了近乎于点源的胶子强子化过程。与γN,eN,πN反应互补,这一新的N*产生源具有同位旋和低自旋筛选的优势。综述了正负电子湮灭过程的核子激发态N*产生的实验情况和相关的唯象进展,同时讨论未来发展的一些新方向,如正负电子湮灭过程的核子激发态N*产物的一些新来源等。Up to now, the N* production from e+e- annihilations has been studied only around charmonium region. Charmonium decays to N*s are analogous to (time-like) EM form factors in that the charm quark annihilation provides a nearly pointlike (ggg) current. Complementary to other sources, such as πN, eN and γN reactions, this new source for N* spectroscopy has a few advantages, such as an isospin filter and a low spin filter. The experimental results on N* from e+e- annihilations and their phenomenological implications are reviewed. Possible new sources on N* production from e+e- annihilations are discussed.  相似文献   

5.
M.  Hashemi 《理论物理通讯》2014,61(1):69-74
In this paper, charged Higgs pair production through l^+l^- → H^+ H^-, where l = e or μ, is studied within the framework of a general Two Higgs Doublet Model (2HDM). The analysis is relevant to a future e^+e^- or μ^+ μ^- collider operating at center of mass energy of √s = 500 GeV. Two different scenarios of small and large a values are studied. Here a is the parameter, which diagonMizes the neutral CP-even Higgs boson mass matrix. Within the Minimal Supersymmetric Standard Model (MSSM), cross section of this process is almost the same at e+ e- and #+#- colliders. It is shown that at e^+e^- eolliders within a general 2HDM, cross section is not sensitive to the mass of neutral Higgs bosons, however, it can acquire large values up to several picobarn at μ^+μ^- colliders with the presence of heavy neutral Higgs bosons. A scan over Higgs boson mass parameter space is performed to analyze the effect of large masses of neutral Higgs bosons involved in the s-channel propagator and thus in the total cross section of this process.  相似文献   

6.
In the minimal supersymmetric standard model (MSSM) with CP violating phases, this paper discusses the production of the lJghtest neutral Higgs boson in association with tau sleptons at future high-energy e^ e^- linear colliders. In parameter space of the constrained MSSM, the production cross section of e^ e^→h^0T1 T1^- can be very substantial at high energies. This process would provide a production mechanism for probing couplings of neutral Higgs bosoas to tau sleptons as well as some soft supersymmetric breaking parameters at next linear colliders.  相似文献   

7.
Virtual effects of supersymmetry on the-flavor changing process at LEPII are calculated in the minimal supersymmetric standard model (MSSM). We analyze the cross section of e+e- → γ, Z0 → tq, and find that even for the most distinguishable mode e+e- → γ, Z0 → tc, the effect is small compared with the SM expectation.  相似文献   

8.
In this paper we investigate the effects of the large extra dimensions on the two processes e+e-→ H0Z0Z0 and e+e-→ H0Z0Z0 at linear colliders in both unpolarized and polarized collision modes. We find that the virtual Kaluza-Klein graviton exchange can significantly enhance the cross section from their standard model expectations for these two processes. The results show that the LED effect on the process e+e-→ H0Z0Z0 allows the observation limits on the effective scale MS to be probed up to 9.75 TeV and 10.1 TeV in the unpolarized and +-(λe+=1/2, λe-=-1/2) polarized beam collision modes (with Pe+=0.6, Pe-=0.8), respectively. For the process e+e-→ H0Z0Z0, these limits on MS can be probed up to 6.06 TeV and 6.38 TeV in the unpolarized and polarized collision modes separately. We find that the λe+=1/2, λe-=-1/2 polarization collision mode in both process e+e-→ H0Z0Z0 and e+e-→ H0Z0Z0 may provide a possibility to improve the sensitivity in probing the LED effects.  相似文献   

9.
Within the context of the Littlest Higgs model with T-parity, the heavy photon (AH) is supposed to be an ideal dark matter (DM) candidate. One direct proof of validity of the model is to produce the heavy photon at collider. In this paper, we investigate the associated production of a photon with heavy photon pair at the planned international e+e- linear collider (ILC), i.e. e+e- → AHAHγ and show the distributions of the transverse momenta of the photon. The numerical results indicate that the heavy photon production rate could reach several fb at the low mass parameter space and the characteristic signal is a single high energetic photon and missing energy, carried by the heavy photons. All in all, it can be a good chance to observe the heavy photon via this process with the high yearly luminosity of the ILC.  相似文献   

10.
Flavor changing effects on the processes t → ch, e+e- → bs, e+e-→ bsh and pp → bs in the LHT model are investigated in this paper. We calculate the one-loop level contributions from the T-parity odd mirror fermions and gauge bosons. The results show that the top quark rare decay t → ch in the LHT model can be significantly enhanced relative to that in the SM. The bs production at linear colliders in the LHT model can enhance the SM cross section a lot and reach 0.1 fb in some parameter space allowed in the experiment. But the heavy gauge boson and mirror fermion loops have small contribution to the processes pp → bs and e+e-→ bsh. So the LHT effect on e+e-→ bs might be detected at future linear colliders, while it is too small to be seen for the e+e-→ bsh and pp → bs processes at future linear colliders and LHC.  相似文献   

11.
The observation of the excess of Z0→e+e-γ can be explained by assuming that Z0 is radiatively decayed into a new scalar particle P0 which is subsequently turned into an e+e- pair. We argue that this assuhption does not conflict with the present experimental results.  相似文献   

12.
13.
We study the rare radiative dileptonic decays B0(Bs)→γ l+l- (l=e,μ) in the standard model. By using the B meson wave function constrained by non-leptonic decays, the branching ratios turn out to be of the order of 10-9 for Bs→γ μ+μ-, γe+e-, and 10-10 for B0→γμ+μ-, γe+e-. Based on the study, these decays are accessible at the near future LHC-b experiment, which are useful to determine the B(Bs) wave function.  相似文献   

14.
We calculate the corrections of extended technicolor(ETC) interactions to the asymmetry parameter ALR and the polarized parameters PL^t,PR^t of the process e^ e^-→tt- in topcolor-assisted multiscale technicolor model.our results show that the ETC efect effect on PR^t in negligibly small which can be safely ignored,and the ETC effect on ALR may be testable at high energy e^ e^- linear collider(LC),FOr 0.03≤ε≤0.1,500GeV≤s○800GeV,the relative correction of PL^t is in the range of 15%≤δPL^t/PL^t,SM≤39%,which will certainly be detected at the LC experiments(for example TESLA).  相似文献   

15.
We study possible observational effects of the two Higgs doublets in the e+e-→bqb0 at the LEP Ⅱ energy. We have found that the observational values can be obviously different from those predicted by the minimal standard model (MSM), but the results depend on the parameters of the extended model. The possibilities of the observation are discussed in some details.  相似文献   

16.
To explain the anomalously large decay rate of Σ+→p+μ+μ-, it was proposed that a new mechanism where a light CP-odd pseudoscalar boson of mA10=214.3 MeV makes a crucial contribution. Later, some authors have studied the transition π0→ e+e- and r → γA10 in terms of the same mechanism and their result indicates that with the suggested mass one cannot fit the data. This discrepancy might be caused by experimental error of Σ+→ p+μ+μ- because there were only a few events. Whether the mechanism is a reasonable one motivates us to investigate the transitions π0→ e+e-;η(η')→ μ+μ-; ηc→ μ+μ-; ηb→τ+τ- within the same framework. It is noted that for π0→ e+e-, the standard model (SM) prediction is smaller than the data, whereas the experimental central value of η→μ+μ- is also above the SM prediction. It means that there should be extra contributions from other mechanisms and the contribution of A10 may be a possible one. Theoretically calculating the branching ratios of the concerned modes, we would check if we can obtain a universal mass for A10 which reconcile the theoretical predictions and data for all the modes. Unfortunately, we find that it is impossible to have such a mass with the same coupling |gl|. Therefore we conclude that the phenomenology does not favor such a light A10, even though a small window is still open.  相似文献   

17.
In the framework of the littlest Higgs model with T-parity(LHT),we study the top quark spin correlation and polarization at the International Linear Collider(ILC).We find that the top quark polarization asymmetry δP t and the left-right asymmetry δA LR can respectively reach-35% and-37.5% for s~(1/2)=500 GeV and s~(1/2)=1000 GeV via e+e-collision,which can reach the observable level at the ILC.By contrast,the spin correlation δC is smaller.The correlation behaviors of these observables at the e+e-collision and the γγ collision will be helpful to distinguish different models and test the LHT model at the ILC.  相似文献   

18.
In the context of the left-right twin Higgs (LRTH) model, we fist study single production of the standard model (SM) top quark via e-γ collisions. We find that the corrections of the LRTH model to the cross section of the process e-γ→νebt might be observed only for f≤750 GeV and the heavy top quark mass scale M≥500 GeV in future high energy linear e+e- collider (LC) experiment with the center-of-mass (CM) energy s½=500 GeV and a yearly integrated luminosity of £=100 fb-1. We also consider single production of the heavy top quark T via e-γ collisions. Our numerical results show that the possible signals of the heavy top quark T might be observed via the decay channel T→φ+b→tbb in future LC experiment with s½=3 TeV and £=500 fb-1.  相似文献   

19.
The Higgs triplet model (HTM) predicts the existence of a pair of doubly charged Higgs bosons H±± . Single production of H±± via eγcollision at the next generation e+e- International Linear Collider (ILC) and the Large Hadron electron Collider (LHeC) is considered. The numerical results show that the production cross sections are very sensitive to the neutrino oscillation parameters. Their values for the inverted hierarchy mass spectrum are larger than those for the normal hierarchy mass spectrum at these two kinds of collider experiments. With reasonable values of the relevant free parameters, the possible signals of the doubly charged Higgs bosons predicted by the HTM might be detected in future ILC experiments.  相似文献   

20.
Inclusive cross sections of η production by e+e- annihilation for c.m. energies between 4.0 and 5.0 GeV are presented. The η production is shown to be correlated with the production of a weakly decaying particle, indicating that its main source is F production. At the 4.42 GeV resonance it is correlated with a low energy photon, suggesting or production. A mass determination of the F is made at 4.42 GeV using the F → ηπ decay channel.  相似文献   

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