共查询到20条相似文献,搜索用时 15 毫秒
1.
We consider the τ leptonic decay $\tau\rightarrow
l\bar{\nu}_{l}\nu_{\tau}$ in the framework of the littlest
Higgs (LH) model and calculate the corrections of new particles to
this decay. We find that the contributions of the charged scalars
can be safely ignored and the LH model is in perfect agreement
with the universality of the couplings of the SU gauge bosons
to the leptonic charged currents. The corrections of the LH model
to the τ leptonic decay $\tau\rightarrow
l\bar{\nu}_{l}\nu_{\tau}$ are not sensitive to the parameter
c, but depend strongly on the parameters f and x. The
precision measured data about the τ leptonic decay demand
that the parameter f approximately equal 3.5 TeV and x>0.1, while agree with the general expectation based on other
phenomenological
explorations. 相似文献
2.
3.
YUE Chong-Xing ZHANG Feng YANG Shuo SUN Yan-Bin 《理论物理通讯》2006,46(5):891-894
In the context of the littlest Higgs (LH) model, we estimate the production cross section of the process e^-у→ e^-H in the future high-energy linear e^+e^- collider (ILC) with the center-of-mass (CM) energy √S = 500 GeV. Our numerical results show that the contributions of the LH model Co this process are very small in most of the parameter space allowed by the electroweak precision measurement data, and are very diffcult to be detected in the future ILC experiments. 相似文献
4.
In the context of the littlest Higgs (LH) model, we estimate the production cross section of the process e-γ→ e-H in the future high-energy linear e e- collider (ILC) with the center-of-mass (CM) energy √S= 500 GeV. Our numerical results show that the contributions of the LH model to this process are very small in most of the parameter space allowed by the electroweak precision measurement data, and are very difficult to be detected in the future ILC experiments. 相似文献
5.
LIU Yao-Bei DU Lin-Lin WANG Xue-Lei 《理论物理通讯》2007,48(4):699-704
The littlest Higgs model is the most economical one among various little Higgs models. In the context of the littlest Higgs (LH) model, we study the process e-γ → veW^-H and calculate the contributions of the LH model to the cross section of this process. The results show that in most of the parameter spaces preferred by the electroweak precision data, the value of the relative correction is larger than 10%. Such correction to the process e-γ →veW^-H is large enough to be detected via e-γ collisions in the future high energy linear e^+ e^- collider (ILC) experiment with the c.m. energy √s = 500 GeV and a yearly integrated luminosity £ = 100fb^-1, which will give an idea/way to test the model. 相似文献
6.
We study theoretically the quantum effects of the littlest Higgs model (LH) mediated by flavor changing one-loop Feynman diagrams on the rare decay process t→ cH^0. The comparison of the decay width in the LH model with that in the standard model (SM) is made. We find that the decay branch ratio of t→ cH^0 in the LH model is at most of the order-10^-12, which is two order larger than in the SM. The numerical results show that the difference between the branch ratios in the LH model and the SM is generally sensitive to the LH model parameters, such as symmetry breaking scale f, Higgs boson mass mH0, and x=v'4f/v^2 in our chosen parameter space, but relatively insensitive to the value choice of the cosine of the mixing angle c and the ratio λ1/λ2. 相似文献
7.
Abazov VM Abbott B Acharya BS Adams M Adams T Alexeev GD Alkhazov G Alton A Alverson G Alves GA Ancu LS Aoki M Arov M Askew A Åsman B Atramentov O Avila C BackusMayes J Badaud F Bagby L Baldin B Bandurin DV Banerjee S Barberis E Baringer P Barreto J Bartlett JF Bassler U Bazterra V Beale S Bean A Begalli M Begel M Belanger-Champagne C Bellantoni L Beri SB Bernardi G Bernhard R Bertram I Besançon M Beuselinck R Bezzubov VA Bhat PC Bhatnagar V Blazey G Blessing S Bloom K Boehnlein A Boline D 《Physical review letters》2011,106(17):171802
We present a search for the standard model Higgs boson (H) in pp collisions at sqrt(s)=1.96 TeV in events containing a charged lepton (?), missing transverse energy, and at least two jets, using 5.4 fb(-1) of integrated luminosity recorded with the D0 detector at the Fermilab Tevatron Collider. This analysis is sensitive primarily to Higgs bosons produced through the fusion of two gluons or two electroweak bosons, with subsequent decay H→WW→?νq'q, where ? is an electron or muon. The search is also sensitive to contributions from other production channels, such as WH→?νbb. In the absence of a signal, we set limits at the 95% C.L. on the cross section for H production σ(pp→H+X) in these final states. For a mass of M(H)=160 GeV, the limit is a factor of 3.9 larger than the cross section in the standard model and consistent with an a priori expected sensitivity of 5.0. 相似文献
8.
Physics of Atomic Nuclei - The authors within the Higgs Boson Working Group of the ATLAS experiment at the LHC performed an analysis of events with two leptons and two hadron jets to study Standard... 相似文献
9.
JETP Letters - The $$\tau \to {{K}^{ - }}{{\pi }^{0}}{{\nu }_{\tau }}$$ decay has been described within the Nambu–Jona-Lasinio model including the contact term and the contribution from an... 相似文献
10.
In this paper, we calculated the new physics contribution to theoretically very clean rare decay
B→Xsνν
in the general two-Higgs-doublet model (model III). Within the considered parameter space, we found that
(a) the new physics contribution can provide one to two orders of enhancement to the branching ratio
B(B→Xsνν) and can saturate the experimental bound
on B(B→Xsνν) in some regions of the parameter space; (b) besides the CLEO data of B→Xsγ, the ALEPH upper
limit on B(B→Xsνν) also leads to further constraint on the size of the Yukawa coupling λtt: λtt< 6.4 for
λbb=2.7 and
mH+=200 GeV. 相似文献
11.
Probing the Lightest New Gauge Boson BH in the Littlest Higgs Model via Processes γγ→ ff^- Bg at ILC
WANG Xue-Lei LIU Su-Zhen ZENG Qing-Guo JIN Zhen-Lan 《理论物理通讯》2008,49(2):421-427
The neutral gauge boson BH with the mass of hundreds GeV is the lightest particle predicted by the littlest Higgs (LH) model, and such particle should be the first signal of the LH model at the planed ILC if it exists indeed. In this paper, we study some processes of the BH production associated with the fermion pair at the ILC, i.e., γγ→ ff^- BH. The studies show that the most promising processes to detect BH amongγγ→ ff^- BH are γγ→ l'^+l'^-BH (l' = e,μ), and they can produce the sufficient signals in most parameter space preferred by the electroweak precision data at the ILC. On the other hand, the signal produced via the certain BH decay modes is typical and such signal can be easily identified from the SM background. Therefore, BH, the lightest gauge boson in the LH model, would be detectable at the photon collider realized at the ILC. 相似文献
12.
13.
We study Bd → φKs decay in extra down-type quarks (EDQS) model with a non-universal Z boson associated with flavor changing neutral currents (FCNCs) at the tree level. With the up-to-date experimental data of Br(Bd → φKs), SCKs, and ACKs, we derive the bounds on the Z-b-s coupling parameter |Ubs | and the new weak phase φ, using the constrained parameter spaces, we finally give predictions for Bd → φφ decay, which could be tested at the Fermilab Tevatron and the LHC-b experiments. 相似文献
14.
By employing the QCD factorization approach for the exclusive B→Vу decays, we study the exclusive decay B→K^*у in the top-quark two-Higgs-doublet mode/(T2HDM). Within the considered parameter space, we find the following conclusions (a) A hght charged-Higgs boson with a mass about 200 GeV is clearly excluded by the date of B→K^*у decay, and this lower limit is comparable with that from the inclusive B→X8*у decay; (b) The theoretical predictions for CP asymmetry of B→K^*у in the T2HDM is always less than 1% in size; and (c) The isospin symmetry breaking for B→K^*у decay in the SM and T2HDM considered here is around 6% in size and well consistent with the data and the general expectations. 相似文献
15.
We study Bd → ø KS decay in extra down-type quarks (EDQS) model with a non-universal Z boson associated with flavor changing neutral currents (FCNCs) at the tree level. With the up-to-date experimental data of Br(Bd → ø KS, SøKS, and AøKS, we derive the bounds on the Z-b-s coupling parameter |Ubs| and the new weak phase ø, using the constrained parameter spaces, we finally give predictions for Bs → øø decay, which could be tested atthe Fermilab Tevatron and the LHC-b experiments. 相似文献
16.
The Higgs decay H →γγ due to the virtual W-loop effect is revisited in the unitary gauge by using the symmetry-preserving and divergent-behavior-preserving loop regularization method,which is realized in the fourdimensional space-time without changing original theory.Though the one-loop amplitude of H →γγ is finite as the Higgs boson in the standard model has no direct interaction with the massless photons at tree level,it involves both tensor-type and scalar-type divergent integrals which can in general destroy the gauge invariance without imposing a proper regularization scheme to make them well-defined.As the loop regularization scheme can ensure the consistency conditions between the regularized tensor-type and scalar-type divergent irreducible loop integrals to preserve gauge invariance,we explicitly show the absence of decoupling in the limit M W /M H → 0 and obtain a result agreeing exactly with the earlier one in the literature.We then clarify the discrepancy of the earlier result from the recent one obtained by R.Gastmans,S.L.Wu and T.T.Wu.The advantage of calculation in the unitary gauge becomes manifest in that the non-decoupling arises from the longitudinal contribution of the W gauge boson. 相似文献
17.
《中国物理C(英文版)》2021,(5)
We report a feasibility study for violation in τ~-→K_Sπ~-v_τ decays at a Super Tau Charm Facility(STCF).With an expected luminosity of 1 ab~(-1) collected by STCF per year at a center-of-mass energy of 4.26 GeV,the statistical sensitivity for CP violation is determined to be of order 9.7×10~(-4) by measuring the decay-rate difference between τ~+→K_Sπ~+v_τ and τ~-→K_Sπ~-v_τ.The analysis is performed using a reliable fast simulation software package,which can describe the detector responses properly and vary the responses flexibly for further optimization.Moreover,the energy-dependent efficiencies for reconstructing τ~-→K_Sπ~-v_τ are presented.The expected CP sensitivity is proportional to 1/~(1/2)L in the energy region from 4.0 to 5.0 GeV.The sensitivity of CP violation is of order3.1 × 10~(-4) with 10 ab~(-1) integrated luminosity,which is equivalent to ten years' data taking in this energy region at STCF. 相似文献
18.
Using the QCD factorization approach, we investigate the electro-weak penguin dominated process 13~ --, q57r~ in the extra down-type quark (EDQS) model. We calculate the effects of new physics (NP) on the branching fraction and direct CP asymmetry of the decay mode. It is found that the branching fraction can be increased by 15~o points or dropped by 13~o points than the standard model (SM) value, and its direct CP asymmetry can be increased by 35% points or dropped by 37% points than the SM one. The effects of NP on the direct CP asymmetry are more obvious than on the branching fraction. If this decay mode could be measured in the upcoming LHCb experiment, these results we obtain will be useful for further studies of the EDQS model. 相似文献
19.
Rare decay processes K→πvv^- and KL→π^0vv^- are considered in the framework of three-site Higgsless model. The contributions of this new physics model to these two decay processes come from the new heavy gauge bosons and the correction terms for the couplings of the ordinary gauge bosons with fermions. Our numerical results show that the branching ratios of these two decay processes can be enhanced by 40% and 50% relative to those predicted by the standard model. 相似文献
20.
Single Production of Vector-Like Top Quark in the Littlest Higgs Model at TeV Energy e-γ Colliders 下载免费PDF全文
The existence of a new coloured vector-like heavy fermion T is a crucial prediction in little Higgs models, which play a key role in breaking the electroweak symmetry. The littlest Higgs model is the most economical one among various little Higgs models. In the context of the littlest Higgs model, we study single production of the new heavy vector-like quark and discuss the possibility of detecting this new particle in the future LC experiment. It is found thai, the production cross section is in the range of 1.7× 10^-3 - 30 fb at TeV energy electron-photon collider with √s- 3 TeV and a yearly integrated luminosity of ,£ = 500 fb^-1. 相似文献