Charged Top-pions Research Articles

Precise photoproduction of the charged top-pions at the LHC with forward detector acceptances

We study the photoproduction of the charged top-pion predicted by the top triangle moose (TTM) model (a deconstructed version of the topcolor-assisted technicolor TC2 model) via the processes $$pp\rightarrow p \gamma p \rightarrow \pi ^\pm _t t +X$$ at the 14 TeV Large Hadron Collider (LHC) including next-to-leading order (NLO) QCD corrections. Our results show that the production cross sections and distributions are sensitive to the free parameters $$\sin \omega $$ and $$M_{\pi _t}$$ . A typical QCD correction value is $$7{-}11~\%$$ and this does not depend much on $$\sin \omega $$ as well as the forward detector acceptances.

Photoproduction of the Charged Top-Pions at the LHeC

The top triangle moose (TTM) model, which can be seen as the deconstructed version of the topcolor-assisted technicolor (TC2) model, predicts the existence of the charged top-pions πt± in low energy spectrum. In the context of this model, we consider photoproduction of πt± via the subprocesses γb → tπt− and at the large hadron-electron collider (LHeC), in which high energy photon beams are generated by using the Compton backscatting method. We find that, as long as the charged top-pions are not too heavy, they can be abundantly produced via 76 collision.

B s → ϕl + l − decays in the topcolor-assisted technicolor model

Using the updated form factors within the light-cone QCD sum rule approach, we calculate the new physics contributions to rare semileptonic $ \overline B {\text{s}} $ → ϕμ + μ − , ϕτ + τ − decays from the new particles appearing in the topcolor-assisted technicolor (TC2) model. In our evaluations, we find that: (i) the branching ratio, normalized forward-backward asymmetry and lepton polarization asymmetries show highly sensitivity to charged toppions contributions and little sensitivity to Z ′ contributions. The TC2 enhancements to the branching ratios of these decays can reach a factor of ~ 2; (ii) the NP enhancement to the forward-backward asymmetry of the decay B s → ϕμ + μ − is in the range −13 % to 3 %, but −9 % to −6 % for decay B s → ϕτ + τ − compared to the SM predictions; (iii) the TC2 model provide an enhancement of about 12 % to the longitudinal polarization asymmetry P L for decay B s → ϕμ + μ −, but a decrease of about 10 % to the transverse polarization asymmetry P T for the decay B s → ϕτ + τ −.

SINGLE CHARGED TOP-PION PRODUCTION AT THE LHeC IN γp COLLISION

In the context of the topcolor-assisted technicolor (TC2) model, we study the productions of the charged top-pion associated with single top, charm or bottom quark in γp collision, which proceed via the subprocesses [Formula: see text], [Formula: see text] and [Formula: see text]. With the electron energy Ee = 50 GeV and photon energy Ep = 7 TeV , we find that the production rates can reach the level of several tens fb for [Formula: see text] production, and hundreds of fb for [Formula: see text] (or [Formula: see text]) productions. So one can expect that enough signals could be produced in the large part of the parameter space. Furthermore, these flavor-changing (FC) productions are extremely suppressed in the standard model (SM). With a large number of events and the clean background, the charged top-pion should be observable at the Large Hadron electron Collider (LHeC) based γp colliders. Thus, such charged top-pion production processes may offer a useful way to test the TC2 model.

Joint production of Z boson and charged top-pion pair at the ILC

In this paper, we investigate the joint production of charged top-pions pair and Z gauge boson in the topcolor-assisted technicolor (TC2) at the International Linear Collider (ILC) via the process e+e- → Zπt+πt-. We calculate the production cross section of the process e+e- → Zπt+πt- and find that the cross section of the process e+e- → Zπt+πt- can reach 1 fb in a reasonable parameter space of the TC2 model. Considering the main decay mode of charged top-pion πt+ → tb, we find that such a production may provide copious events at the ILC.

Searches for the technicolor signatures via gg → W±πt∓ at the Large Hadron Collider

In this paper, we calculate the production of a charged top pion in association with a W boson via gg fusion at CERN's Large Hadron Collider in the context of the topcolor assisted technicolor model. We find that the total cross section of pp → gg → W±πt∓ is several dozen femtobarns with reasonable values of the parameters, and the total cross section of pp → W±πt∓ can reach a few hundred femtobarns when we consider the sum of the contributions of these two parton subprocesses, gg → W±πt∓ and bb̄ → W±πt∓.

Charged top-pion production associated with the bottom quark pair as a probe of the topcolor-assisted technicolor model at the LHC

The topcolor-assisted technicolor (TC2) model predicts the existence of the charged top-pions ($\pi_t^\pm$), whose large couplings with the third generation fermions will induce the charged top-pion production associated with the bottom and anti-bottom quark pair at the CERN Large Hadron Collider (LHC) through the parton processes $c\bar b \to \pi_t^+ b \bar b$ and $u\bar d(c\bar s) \to \pi_t^+ b \bar b$. In this paper we examine these productions and find that, due to the small Standard Model backgrounds, their production rates can exceed the $3\sigma$ sensitivity of the LHC in a large part of parameter space, so these processes may serve as a good probe for the TC2 model.

PAIR PRODUCTION OF CHARGED TOP-PIONS ASSOCIATED WITH Z GAUGE BOSON IN THE TOPCOLOR-ASSISTED TECHNICOLOR MODEL AT THE ILC

The top-pions [Formula: see text] are the three additional typical particles predicted by the topcolor-assisted technicolor (TC2) model and the observation of these particles can be regarded as the direct evidence of the TC2 model. In this paper, we investigate the production of a pair of charged top-pions associated with Z gauge boson at the International Linear Collider (ILC), i.e. [Formula: see text] and [Formula: see text]. We calculate the production rate of the process [Formula: see text] and present the distributions of the transverse momenta of Z gauge boson and charged top-pion [Formula: see text]. We find that the cross-section of the process [Formula: see text] can reach 1 fb with reasonable parameter space of the TC2 model. Considering the main decay mode of charged top-pion, we find that such a production may provide copious events. While the cross-section of the process [Formula: see text] is below 1 fb, hence the process [Formula: see text] will play an important role in the test of the TC2 model at the ILC when compared with the process [Formula: see text].

Charged Top-Pion Production at e+e− and γγ Colliders

We study the charged top-pion in the topcolor assisted technicolor model(TC2), and calculate the production of charged top-pion at e+e− and γγ colliders. At an e+e− collider, charged top-pion can be produced via the processes e+e− → tbb̄π−t(t̄bπ+t). At a γγ collider, it can be produced via the processes γγ → tb̄π−t(t̄bπ+t). The cross section can reach to a few of fb depending on the mass of the charged top-pion.

Technicolor corrections tobb¯→W±πt∓at the CERN Large Hadron Collider

In this paper we calculate the technicolor correction to the production of a charged top pion in association with a $W$ boson via $b\overline{b}$ annihilation at the CERN Large Hadron Collider in the context of the topcolor assisted technicolor model. We find that the cross section of $pp\ensuremath{\rightarrow}b\overline{b}\ensuremath{\rightarrow}{W}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}_{t}^{\ensuremath{\mp}}$ at the tree level can reach a few hundred femtobarns for reasonable ranges of the parameters, roughly corresponding to the result of the process $pp\ensuremath{\rightarrow}b\overline{b}\ensuremath{\rightarrow}{W}^{\ifmmode\pm\else\textpm\fi{}}{H}^{\ensuremath{\mp}}$ in the minimal supersymmetric standard model; the relative corrections arising from the one-loop diagrams are about a few percent to two dozen percent, and they will increase the cross section at the tree level. As a comparison, we also discuss the size of the hadron cross section via the other subprocess $gg\ensuremath{\rightarrow}{W}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}_{t}^{\ensuremath{\mp}}$.

Charged Top-Pion Production at Hadron Colliders

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 πt+ → tb̄. We also calculated the production of charged 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.

THE PRODUCTION OF THE NEUTRAL AND CHARGED TOP PIONS ASSOCIATED WITH THE W BOSON AT THE ILC

The top pions [Formula: see text] are the typical particles predicted by the top-color-assisted technicolor (TC2) model, and the observation of these particles can be regarded as the direct evidence of the TC2 model. In this paper, we study the charged and neutral top pion production process [Formula: see text]. The results show that the production rates can reach the level of tens of fb with reasonable parameter values. So one can expect that enough signals could be produced in the International Linear Collider (ILC) experiments. Furthermore, the flavor-changing (FC) decay mode [Formula: see text] is the best channel for detecting the neutral 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 in future ILC experiments.

Charged Top-Pion Production Associated with a Gluon Jet at the LHC

The charged top-pions have been predicted by the topcolour-assisted technicolour (TC2) model and the observation of the charged top-pions can be regarded as the robust evidence of the model. We study the charged top-pion and gluon associated production at the LHC, i.e., pp ↠ g ∏t+. The cross section of this process can reach tens of pb, even hundreds ofpb, and there will be enough g∏t+ events produced at the LHC. Because the g∏t+ production is a flavour-changing (FC) process, the SM background can be greatly depressed. Furthermore, there exists an FC decay mode cb̄ for the charged top-pions, and such decay mode can provide us with the typical signals to detect the charged top-pions. Therefore, it is hopeful to find the charged top-pions via the g∏t+ production at the LHC.

Production of the charged top-pions from TC2 model at the TeV energy e-γ colliders

The top-pions (Πt0,±) and the top-Higgs (ht0) are the typical particles predicted by the topcolor-assisted technicolor (TC2) model and the observation of these particles can be regarded as direct evidence of the TC2 model. In this paper, we study three pair production processes of these new particles at the next generation eγ colliders, i.e., e-γ→e-Πt+Πt-, e-γ→νeΠt-Πt0 and e-γ→νeΠt-ht0. The results show that the production rates can reach the level 100–101 fb with reasonable parameter values. So one can expect that enough signals could be produced in future high- energy linear collider experiments. Furthermore, the flavor-changing (FC) decay modes Πt-→bc, Πt0(ht0)→tc can provide us with the typical signal to detect these new particles.

The productions of the top-pions and top-Higgs associated with the charm quark at the hadron colliders

In the topcolor-assistant technicolor (TC2) model, the typical physical particles, top-pions and top-Higgs, are predicted and the existence of these particles could be regarded as the robust evidence of the model. These particles are accessible at the Tevatron and LHC, and furthermore the flavor-changing(FC) feature of the TC2 model can provide us a unique chance to probe them. In this paper, we study some interesting FC production processes of top-pions and top-Higgs at the Tevatron and LHC, i.e., $c\Pi_{t}^{-}$ and $c\Pi_{t}^{0}(h_{t}^{0})$ productions. We find that the light charged top-pions are not favorable by the Tevatron experiments and the Tevatron has a little capability to probe neutral top-pion and top-Higgs via these FC production processes. At the LHC, however, the cross section can reach the level of $10\sim 100$ pb for $c\Pi_t^-$ production and $ 10\sim 100$ fb for $c\Pi_t^0(h_t^0)$ production. So one can expect that enough signals could be produced at the LHC experiments. Furthermore, the SM background should be clean due to the FC feature of the processes and the FC decay modes $\Pi_t^-\to b\bar{c}, \Pi_t^0(h_t^0)\to t\bar{c}$ can provide us the typical signal to detect the top-pions and top-Higgs. Therefore, it is hopeful to find the signal of top-pions and top-Higgs with the running of the LHC via these FC processes.

Associated production of the top-pions and single top at hadron colliders

In the context of topcolor-assisted technicolor (TC2) models, we study the production of the top-pions ${\ensuremath{\pi}}_{t}^{0,\ifmmode\pm\else\textpm\fi{}}$ with single top quark via the processes $p\overline{p}\ensuremath{\rightarrow}t{\ensuremath{\pi}}_{t}^{0}+X$ and $p\overline{p}\ensuremath{\rightarrow}t{\ensuremath{\pi}}_{t}^{\ifmmode\pm\else\textpm\fi{}}+X$, and discuss the possibility of detecting these new particles at Tevatron and LHC. We find that it is very difficult to observe the signals of these particles via these processes at Tevatron, while the neutral and charged top-pions ${\ensuremath{\pi}}_{t}^{0}$ and ${\ensuremath{\pi}}_{t}^{\ifmmode\pm\else\textpm\fi{}}$ can be detecting via considering the same sign top pair $tt\overline{c}$ event and the $tt\overline{b}$ (or $t\overline{t}b$) event at LHC, respectively.

Single Charged Top-Pion Production at the Next Generatione+e− Colliders

The single charged top-pion production processese+e−→tb̄Πt− and e+e−→W+Πt− are studied in the framework of top-color-assistedtechnicolor (TC2) model. Our studies show that the cross sectionσ(e+e−→tb̄Πt−) reaches the level oftens of fb and σ(e+e−→W+Πt−) reaches thelevel of a few fb. With the yearly integrated luminosity of£∼500 fb−1 expected at the planned colliders, onecould collect thousands of charged top-pion of events via the processe+e−→tb̄Πt− and hundreds of events via theprocess e+e−→W+Πt−. The flavor changing decaymode Π−t→bc̄ is the best channel to detectcharged top-pion due to the clean SM background. With a largenumber of events and the clean background, the charged top-pionshould be observable at the planned colliders. Therefore, ourstudies in this paper can help us to search for charged top-pion,and furthermore, to test the TC2 model.

W±πt∓ Associated Production at Large Hadron Collider**The project supported by the Natural Science Foundation of Henan Province of China under Grant No. 0311012700

In this paper we calculate the production of a charged top pion in association with a boson at the CERN Large Hadron Collider (LHC) in the context of the topcolor assisted technicolor model. We find that the cross section of is roughly corresponding to the result of the process in the minimal supersymmetric standard model, and for reasonable ranges of the parameters, the cross section can reach a few hundred fb. The signal should be clearly visible at LHC unless is very heavy.

Study on Charged Top-Pion Decay Processes**The project supported by National Natural Science Foundation of China under Grant No. 10175017, the Excellent Youth Foundation of Henan Scientific Committee under Grant No. 02120000300, and the Henan Innovation Project for University Prominent Research Talents under Grant No. 2002kycx009

In the framework of top-color assisted technicolor (TC2) theory, we study the four decay processes of charged top-pion, i.e., . The decay branching ratio of these modes are calculated. The results show that the main decay channels of charged top-pion are the tree level modes: and . Light is easier to be detected than heavy one at future coliders. So, the study provides us with some useful informations to search for charged top-pion.

Production of the top-pions at the THERA collider based γp collisions

In the framework of the topcolor-assisted technicolor (TC2) models, we study the production of the top-pions π0t, πt± via the processes ep→γc→π0tc and ep→γc→π±tb mediated by the anomalous top coupling tcγ. We find that the production cross section of the process ep→γc→π0tc is very small. With reasonable values of the parameters in TC2 models, the production cross section of the process ep→γc→π±tb can reach 1.2 pb. The charged top-pions π±t might be directly observed via this process at the THERA collider based γp collisions.