We analyze two versions of the extended technicolor (ETC) incorporating the top quark condensate via the flavor-universal coloron type topcolor $SU(3)_1 \times SU(3)_2$: A straightforward top-mode ETC having quarks and techniquarks assigned to a single (strong) $SU(3)_1$, and a ``twisted model'' with techniquarks carrying the weak $SU(3)_2$ while quarks the strong $SU(3)_1$. The straightforward model has the same ETC structure as that of Appelquist et al. without topcolor which we first analyze to find that it yields only too small ETC-induced mass for the third generation. In contrast, our model having topcolor takes the form of a version of the topcolor-assisted technicolor (TC2) after ETC breakings, which triggers the top quark condensate giving rise to a realistic top mass. However, techniquarks have the strong topcolor $SU(3)_1$ in addition to the already strong walking/conformal technicolor, which triggers the techniquark condensate at scale much higher than the weak scale, a disaster. We then consider a ``twisted model'' of TC2, though not an explicit ETC. We find a new feature that ``ETC''-induced quark mass is enhanced to the realistic value by the large anomalous dimension $γ_m \simeq 2$ of Nambu-Jona-Lasinio-type topcolor interactions. The result roughly reproduces the realistic quark masses. We further find a novel effect of the above large anomalous dimension $γ_m \simeq 2$: The top-pion mass has a universal upper bound, $m_{π_t} < 70 \GeV$, in the generic TC2 model.
Conventional technicolor models with light charged technipions ($π^{\pm} _T$) lead to an unacceptably large contribution to $t\ra {π^+_T} b$ decay rate. Topcolor-assisted technicolor models also have additional PGBs called top-pions ($π^{\pm}_t$) which may contribute to this decay. We study the potentially dangerous mixing of charged top-pion and technipions in toy models of `natural' topcolor-assisted technicolor. We find that the $t\ra {π^+_{t,T}} b$ decay rate in such models can be within experimental limits due to a combination of heavy top-pion and small $π_t - π_T$ mixing.
A condensate, $\overline{t}t$, arising from $O(TeV)$ scale ``topcolor,'' in addition to technicolor (and ETC) may naturally explain the gauge hierarchy, the large top quark mass, and contains a rich system of testable consequences. A triplet of strongly coupled pseudo--Nambu--Goldstone bosons, ``top-pions,'' near the top mass scale is a generic prediction of the models. A new class of technicolor schemes and associated phenomenology is suggested in this approach.
We construct a prototype of topcolor--assisted technicolor in which, although both top and bottom quarks acquire some mass from extended technicolor, strong $U(1)$ couplings of technifermions are isospin symmetric and all gauge anomalies vanish. There is a mechanism for mixing between the light and heavy generations and there need be no very light pseudo--Goldstone bosons.
We use the LEP/SLD data to place constraints on Topcolor Assisted Technicolor Models. We find that due to a large negative shift in R_b induced by charged top-pion exchange, it is difficult to make the models compatible with experiment.
We consider a model combining technicolor with the top quark condensation. As a concrete model for Technicolor we use the Minimal Walking Technicolor, and this will result in the appearance of a novel fourth generation whose leptons constitute a usual weak doublet while the QCD quarks are vectorlike singlets under the weak interactions. We carry out an analysis of the mass spectra and precision measurement constraints, and find the model viable. We contrast the model with present LHC data and discuss the future prospects.
We study top quark pair productions at a polarized photon collider from an e(+)e(-) linear collider (LC) in various improved technicolor model, namely, the one-family walking technicolor model, the top-color-assisted technicolor model, and the top-color-assisted multiscale technicolor model. Recent constraint on the top-pion mass from the precision data of R(b) is considered. It is shown that, considering only the statistical errors, a polarized photon collider from a 500 GeV LC with an integrated luminosity of 500 inverse fb is sufficient for distinguishing the three improved technicolor mode…
We discuss a model which involves the top quark condensation and the walking technicolor. We focus on the scalar boson in such a model from the viewpoint of the observed scalar boson at the LHC.
Topcolor-assisted technicolor provides a dynamical explanation for electroweak and flavor symmetry breaking and for the large mass of the top quark without unnatural fine tuning. I briefly review the basics of topcolor-assisted technicolor, including major constraints and a general approach to satisfying them. The main challenge to topcolor-assisted technicolor is to generate the observed mixing between heavy and light generations while breaking the strong topcolor interactions near 1 TeV. I argue that these phenomena, as well as electroweak symmetry breaking, are intimately connected and I pr…
I present a model of topcolor-assisted technicolor that can have topcolor breaking of the desired pattern, hard masses for all quarks and leptons, mixing among the heavy and light generations, and explicit breaking of all technifermion chiral symmetries except electroweak $SU(2) \otimes $U(1). These positive features depend on the outcome of vacuum alignment. The main flaw in this model is tau-lepton condensation.
Using precision electroweak data, we put limits on ``natural'' top-color assisted technicolor models. Generically the new $U(1)$ gauge bosons in these models must have masses larger than roughly 2 TeV, although in certain (seemingly unrealistic) models the bound can be much lower.
In the framework of topcolor-assisted technicolor(TC2) models, we calculate the contributions of flavor changing scalar couplings involved the neutral top-pion $π_{t}^{0}$ and top-Higgs $h_{t}^{0}$ to the branching ratio $B_{r}(t\longrightarrow cg)$. We find that the value of $B_{r}(t\longrightarrow cg)$ can reach $ 1\times10^{-3}$ with reasonable values of the parameters in TC2 models, which may be testable in the future experiments.
We comparatively analyze the flavor changing neutral current process of the $Λ_b \rightarrow Λ\ell^+ \ell^-$ in the standard model as well as topcolor-assisted technicolor model using the form factors calculated via light cone QCD sum rules in full theory. In particular, we calculate the decay width, branching ratio and lepton forward-backward asymmetry related to this decay channel. We compare the results of the topcolor-assisted technicolor model with those of the standard model and debate how the results of the topcolor-assisted technicolor model depart from the standard model predictions. …
We present a model of dynamical electroweak symmetry breaking in which the splitting between the top and bottom quark masses arises naturally. The W and Z masses are produced by a minimal technicolor sector, the top quark mass is given by the exchange of a weak-doublet technicolored scalar, and the other quark and lepton masses are induced by the exchange of a weak-doublet technicolor-singlet scalar. We show that, in the presence of the latter scalar, the vacuum alignment is correct even in the case of SU(2) technicolor. The fit of this model to the electroweak data gives an acceptable agreeme…
We calculate the rates for lepton number violating processes via the exchange of the Z' boson occuring in top-color assisted technicolor. The current experimental limits on muon electron conversion in Ti nuclei allow for a mass of the new gauge boson around 1 TeV and the magnitudes of the mixing angles turn out to lie roughly between the analogous elements of the CKM matrix and its square root.
Recent study on the charged top-pion correction to R_b shows that it is negative and large, so that the precision experimental value of R_b gives rise to a severe constraint on the topcolor-assisted technicolor models such that the top-pion mass should be of the order of 1 TeV. In this paper, we restudy this constraint by further taking account the extended technicolor gauge boson correction which is positive. With this positive contribution to R_b, the constraint on the topcolor-assisted technicolor models from R_b changes significantly. The top-pion mass is allowed to be in the region of a f…
Pair-production of heavy top quarks at the Tevatron Collider is significantly enhanced by the color--octet technipion, $η_T$, occurring in multiscale models of walking technicolor. We discuss $\bar tt$ rates for $m_t = 170$ GeV and $M_{η_T} = 400-500$ GeV. Multiscale models also have color--octet technirho states in the mass range 200-600 GeV that appear as resonances in dijet production and technipion pair--production.
We calculate the contributions to the rare decays $B \to X_{s,d} ν\bar ν$ and $B_{s,d} \to l^+l^-$ from one-loop $Z^0$-penguin diagrams in the framework of Topcolor-assisted Technicolor Model. Within the parameter space, we find that: (a) the new contribution from technipions is less than 2% of the standard model prediction; (b) the top-pions can provide a factor of 10 to 30 enhancement to the ratios in question; (c) the topcolor-assisted technicolor model is consistent with the current experimental data.
In the context of topcolor-assisted technicolor (TC2) models, we consider the process $e^{+}e^{-}\to ν\barνγ$ and calculate the cross section of this process at leading order.It is shown that the extra U(1) gauge boson $Z^{\prime}$ predicted by TC2 models can give significant contributions to the process $e^{+}e^{-}\to ν_τ\barν_τγ$, which may be detected in the future high energy linear $e^{+}e^{-}$ collider(LC) experiments.
Topcolor-assisted technicolor (TC2) model predicts the existence of the top-pions and the CP-even top-Higgs with large flavor-changing couplings to the top quark, which at tree-level can mediate the top quark three-body decay t -> cb\bar{b}. In this work we study this decay, showing the dependence of the decay rate on the relevant TC2 parameters and comparing the results with the predictions in the minimal supersymmetric model. We find that the decay rate in the TC2 model is much larger than in the minimal supersymmetric model and, in a large part of the parameter space, the TC2 prediction may…
We consider the flavor changing neutral current(FCNC) process $e^{+}e^{-}\to\bar{t}c$(or $t\bar{c}$) in the context of topcolor-assisted technicolor(TC2) models. We find that the contributions of charged scalars (technipions and top-pions) and topcolor gauge bosons are negligibly small. The neutral scalars (top-pion $π_{t}^{0}$ and top-Higgs $h_{t}^{0}$) can give significant contributions to this process. With reasonable values of the parameters in TC2 models, there will be several tens of the observable $\bar{t}c$ events to be generated in the future $e^{+}e^{-}$ linear colliders.
Pseudo-Goldstone boson contributions to $t\bar{t}$ production rates in technicolor models with and without topcolor at the $\sqrt{s}=0.5 and 1.5$ TeV photon colliders and hadron colliders are reviewed. For reasonable ranges of the parameters, the contributions are large enough to be experimentally observable. Models with topcolor, without topcolor and the MSSM with $\tanβ\geq 1$ can be experimentally distinguished.
Based on previous studies computing coefficients of the electroweak chiral Lagrangian from C.T.Hill's schematic topcolor-assisted technicolor model, we generalize the calculation to K.Lane's prototype natural topcolor-assisted technicolor model. We find that typical features of the model are qualitatively similar as those of Hill's model, but Lane's model prefers smaller technicolor group and Z' mass must be smaller than 400GeV, further S parameter is around order of +1 mainly due to existence of three doublets of techniquarks. We obtain the values for all coefficients of the electroweak chira…
We study the single top quark production process in various kinds of technicolor models in high energy positron photon collisions at the future electron positron linear colliders. It is shown that if there is certain charged pseudo Goldstone boson (PGB) coupling to t(anti-b), the t(anti-b)-channel PGB contribution is dominant, but the situation is quite different from that in the neutral channel, t(anti-t) production in photon photon collisions, due to the destructive nature of different amplitudes. At the DESY limear collider TESLA, the event rates in models with t(anti-b)-channel PGB contrib…
We study pseudo-Goldstone boson corrections to top quark pair production rates in technicolor models with and without topcolor at the E=0.5 teV and 1.5 TeV photon colliders. We find that, for reasonable ranges of the parameters, the corrections are large enough to be observable, and the corrections in models with topcolor are considerably larger than those in models without topcolor, and they are all significantly larger than the corresponding corrections in the minimal supersymmetric standard model (MSSM) with tan(beta) of the order of 1. So that the two kinds of technicolor models and the MS…
We consider the rare top quark decays in the framework of topcolor-assisted technicolor (TC2) model. We find that the contributions of top-pions and top-Higgs predicted by the TC2 model can enhance the SM branching ratios by as much as 6-9 orders of magnitude. i.e., in the most case, the orders of magnitude of branching ratios are $Br(t\to c g)\sim 10^{-5}$, $Br(t\to c Z)\sim 10^{-5}$, $Br(t\to c γ)\sim 10^{-7}$. With the reasonable values of the parameters in TC2 model, such rare top quark decays may be testable in the future experiments. So, rare top quark decays provide us a unique way to t…
In the framework of topcolor-assisted technicolor model we calculate the contributions from the pseudo Goldstone bosons and new gauge bosons to $e^+e^- \to t\bar{t}$. We find that, for reasonable ranges of the parameters, the pseudo Goldstone bosons afford dominate contribution, the correction arising from new gauge bosons is negligibly small, the maximum of the relative corrections is -10% with the center-of-mass energy $\sqrt{s}=500$ GeV; whereas in case of $\sqrt{s}=1500$ GeV, the relative corrections could be up to 16%. Thus large new physics might be observable at the experiments of next-…
We explore corrections to electroweak parameters in the context of Extended Technicolor (ETC) models in which the ETC gauge-boson which generates the top-quark mass carries weak $SU(2)$ charge. For $m_t \sim 150$ GeV there exist potentially large corrections to the $Z$ decay width to $b$-quarks. Interestingly, in contrast to the situation in ETC models where the gauge-boson which generates the top-quark mass is a weak $SU(2)$ singlet, the corrections may {\it increase} the $Z \to b \bar{b}$ branching ratio.
In the framework of topcolor-assisted technicolor (TC2) theory, we calculate the contributions of the scalars(the neutral top-pion $π_{t}^{0}$ and the top-Higgs $h_{t}^{0}$) to the flavor-changing rare top decays $t\to c V V$(V= W, g, $γ$ or Z). Our results show that $h_{t}^{0}$ can enhance the standard model $B_{r}^{SM}(t\longrightarrow cWW)$ by several orders of magnitude for most of the parameter space. The peak of the branching ratio resonance emerges when the top-Higgs mass is between $2m_{W}$ and $m_{t}$. The branching ratio $ B_{r}(t\to c W W)$ can reach $ 10^{-3}$ in the narrow range.
Extended technicolor (ETC) theories typically require ETC gauge bosons lighter than of order 1 TeV, to perturbatively generate the $t$ quark mass. We point out that explicit models of $t-b$ mass splitting also typically contain additional TeV scale ETC gauge bosons transforming in the {\it adjoint} of technicolor, leading to large weak-isospin-breaking effects observable in the $ρ$ parameter. Viable ETC models may thus require a lowest ETC scale of order 10 TeV, with relatively strong and finely tuned couplings to generate $m_t$. Such models do not generate observable corrections to the $Zb{\b…
The topcolor-assisted technicolor (TC2) model predicts several pseudo-scalars called top-pions and at loop level they can induce the FCNC top quark decay t->cgg which is extremely suppressed in the Standard Model (SM). We find that in the allowed parameter space the TC2 model can greatly enhance such a FCNC decay and push the branching ratio up to 10^{-3}, which is much larger than the predictions in the SM (10^{-9}) and in the minimal supersymmetric model (10^{-4}). We also compare the result with the two-body FCNC decay t-> cg and find that the branching ratio of t-> cgg is slightly larger t…
In the framework of the topcolor-assisted technicolor (TC2) models, we study the productions of a single top or bottom quark associated with a scalar in γ-p collision, which proceed via the subprocesses cγ-> tπ_t^0, cγ-> t h_t^0 and cγ-> bπ^+_t mediated by the anomalous top or bottom coupling tcπ_t^0, tch_t^0 and bcπ_t^+. These productions, while extremely suppressed in the Standard Model, are found to be significantly enhanced in the large part of the TC2 parameter space, especially the production via cγ-> bπ^+ can have a cross section of 100 fb, which may be accessible and allow for a test o…
Contributions to the muon anomalous magnetic moment are evaluated in the technicolor model with scalars and topcolor assisted technicolor model. In the technicolor model with scalars, the additional contributions come from the loops of scalars, which were found sizable only for a very large $f/f^{'}$ disfavored by the experiment of $b\to sγ$. The topcolor effect is also found to be large only for an unnaturally large $\tanθ'$, and thus the previously evaluated loop effects of extended technicolor bosons, suppressed by $m_μ^2/M_{ETC}^2$, must be resorted to account for the E821 experiment. So, …
In the context of flavor-universal topcolor-assisted technicolor (TC2) models, we calculate the lepton flavor violating (LFV) $Z\to l_il_j$ decays. We find that the extra U(1) gauge boson $Z^{\prime}$ can give significant contributions to these LFV processes. With reasonable values of the parameters, the branching ratios of the processes $Z\to τμ$ and $Z\to τe$ can approach the experimental upper limits. The indirect bound on the process $Z\to μe$ can give a severe constraint on the flavor-universal TC2 models.
We discuss and estimate the contributions of the new particles predicted by topcolor assisted technicolor(TC2) models to the muon anomalous magnetic moment $a_μ$. Our results show that the contributions of Pseudo Goldstone bosons are very small which can be safely ignored. The main contributions come from the ETC gauge boson $x_μ$ and topcolor gauge boson $Z^{\prime}$. If we demand that the mass of $Z^{\prime}$ is consistent with other experimental constrains, its contributions are smaller than that of $x_μ$. With reasonable values of the parameters in TC2 models, the observed BNL results for …
The topcolor-assisted technicolor (TC2) model predicts a number of neutral scalars like the top-pion ($π^0_t$) and the top-Higgs ($h^0_t$). These scalars have flavor-changing neutral-current (FCNC) top quark couplings, among which the top-charm transition couplings may be sizable. Such FCNC couplings induce single top productions associated with a neutral scalar at the CERN Large Hadron Collider (LHC) through the parton processes $cg \to t π_t^0$ and $cg \to t h_t^0$. In this note we examine these productions and find their production rates can exceed the $3σ$ sensitivity of the LHC in a large…
Based on previous studies deriving the chiral Lagrangian for pseudo scalar mesons from the first principle of QCD, we derive the electroweak chiral Lagrangian and build up a formulation for computing its coefficients from one-doublet technicolor model and a schematic topcolor-assisted technicolor model. We find that the coefficients of the electroweak chiral Lagrangian for the topcolor-assisted technicolor model are divided into three parts: direct TC2 interaction part, TC1 and TC2 induced effective Z' particle contribution part, and ordinary quarks contribution part. The first two parts are c…
We construct a complete, realistic, and natural UV completion of minimal conformal technicolor that explains the origin of quark and lepton masses and mixing angles. As in "bosonic technicolor", we embed conformal technicolor in a supersymmetric theory, with supersymmetry broken at a high scale. The exchange of heavy scalar doublets generates higher-dimension interactions between technifermions and quarks and leptons that give rise to quark and lepton masses at the TeV scale. Obtaining a sufficiently large top quark mass requires strong dynamics at the supersymmetry breaking scale in both the …
We study the Yukawa corrections to the gamma gamma --> b\bar{b} corss section in the topcolor assisted technicolor models at the photon-photon colliders. We find that, for the favorable parameters, the relative corrections from pseudo Goldstone bosons give out a 3.2%--5.9% decrement of the cross section from the tree level when \sqrt{s}=500 GeV, the contributions from new extended technicolor gauge bosons Z* and colored gauge bosons B are negligibly small, and the relative correction arising from new color-singlet heavy gauge boson Z' is less than -3.2%. Therefore, the total relative correctio…
We estimate the correction to the Zbb-bar vertex arising from the exchanges of the sideways extended technicolor (ETC) boson and the flavor-diagonal ETC boson in the multiscale walking technicolor model. The obtained result is too large to explain the present data. However, if we introduce a new self- interaction for the top quark to induce the top quark condensate serving as the origin of the large top quark mass, the corrected R_b=Gamma_b/Gamma_h can be consistent with the recent LEP data. The corresponding correction to R_c=Gamma_c/Gamma_h is shown to be negligibly small.
Topcolor--assisted technicolor provides a dynamical explanation for electroweak and flavor symmetry breaking and for the large mass of the top quark without unnatural fine tuning. A major challenge is to generate the observed mixing between heavy and light generations while breaking the strong topcolor interactions near~$1\,\tev$. I argue that these phenomena, as well as electroweak symmetry breaking, are intimately connected and I present a scenario for them based on nontrivial patterns of technifermion condensation. I also exhibit a class of models realizing this scenario. This picture leads…
It is argued that the topcolor models recently proposed by Hill [1] may face significant constraints from flavor-changing neutral current processes (such as $B-\bar{B}$ mixing) unless the mixing angles between down-type quarks are small. The flavor-changing processes are mediated by scalar bound states which are likely to be light as a result of the near critical dynamics of the $b$-quark sector. The consequences of the latter on the bottom quark mass are also briefly discussed.
The topcolor-assisted technicolor (TC2) model predicts the existence of the charged top-pions ($π_t^\pm$), 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 $c\bar b \to π_t^+ b \bar b$ and $u\bar d(c\bar s) \to π_t^+ b \bar b$. In this paper we examine these productions and find that, due to the small Standard Model backgrounds, their production rates can exceed the $3σ$ sensitivity of the LHC in a large part of parameter…
We consider the lepton-flavor violating(LFV) processes $l_{i}\to l_{j}γ$ in the framework of topcolor assisted technicolor(TC2) models. We find that the new gauge boson $Z^{\prime}$ predicted by TC2 models can give significantly contributions to these processes via the flavor changing couplings. The present experimental bound on the LFV process $μ\to eγ$ gives severe constraints on the TC2 models. In the case that the $Z^{\prime}$ mass $M_{Z}$ is consistent with other experimental constraints, we obtain constraints on the lepton mixing factors $K_{τμ}$ and $K_{τe}$. The future LFV experiments …
These two lectures on technicolor and extended technicolor (ETC) were presented at l'Ecole de GIF at LAPP, Annecy-le-Vieux, France, in September 2001. In Lecture I, the motivation and structure of this theory of dynamical breaking of electroweak and flavor symmetries is summarized. The main phenomenological obstacles to this picture--flavor-changing neutral currents, precision electroweak measurements, and the large top-quark mass--are reviewed. Then, their proposed resolutions--walking technicolor and topcolor-assisted technicolor are discussed. In Lecture II, a scenario for CP violation is p…
Recently, Hill has proposed a model in which new, potentially low-energy, top-color interactions produce a top-condensate ({\em a la} Nambu---Jona-Lasinio) and accommodate a heavy top quark, while technicolor is responsible for producing the $W$ and $Z$ masses. Here we argue that isospin breaking gauge interactions, which are necessary in order to split the top and bottom quark masses, are likely to couple to technifermions. In this case they produce a significant shift in the $W$ and $Z$ masses (i.e.~contribute to $Δρ_* = αT$) if the scale of the new interactions is near 1 TeV. In order to sa…
In the context of topcolor-assisted technicolor (TC2) models, we examine the flavor changing (FC) Z decay $Z\to b\bar{s}(\bar{b}s)$ and calculate the contributions of the new particles predicted by TC2 models to the branching ratio Br($Z\to b\bar{s}+\bar{b}s$). We find that the contributions mainly come from the top-pions. In most of the parameter space, the Br($Z\to b\bar{s}+\bar{b}s$) can reach $10^{-5}$, which may be detected in near future experiments such as Giga-Z version of the TESLA. Thus, the FC Z decay $Z\to b\bar{s}(\bar{b}s)$ can be used to test TC2 models.
The top-pions($Π^{0,\pm}$) and the top-Higgs($H_{TC}$) are the 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 study two pair production processes of these new particles, i.e., $e^ + e^ - \to H_{TC}Π^0$ and $e^+e^-\to Π^+Π^-$. The results show that the production rates are at the level of serval fb for $e^ + e^ - \to H_{TC}Π^0$ and tens fb for $e^+e^-\to Π^+Π^-$. These processes can produce the adequate distinct multi-jet final states and the SM backgro…
We study the top quark pair production process p+p(anti-p)-->top+antitop in various kinds of technicolor (TC) models at the Fermilab Tevatron Run II and the CERN LHC. The s-channel neutral pseudo-Goldstone bosons (PGB's) contribute dominately to the production amplitudes from its coupling to the gluons through the triangle loops of techniquarks and the top quark. Cross sections in different TC models with s-channel PGB contributions are calculated. It is shown that the PGB effects can be experimentally tested and different TC models under consideration can be distinguished at the LHC. Therefor…
New physics beyond the Standard Model can lead to extra matter effects on neutrino oscillation if the new interactions distinguish among the three flavors of neutrino. In Ref.1, we argued that a long-baseline neutrino oscillation experiment in which the Fermilab-NUMI beam in its high-energy mode is aimed at the planned Hyper-Kamiokande detector would be capable of constraining the size of those extra matter effects, provided the vacuum value of \sin^2 2θ_{23} is not too close to one. In this talk, we discuss how such a constraint would translate into limits on the coupling constants and masses…
We investigate the contribution of technicolor mechanisms to the production of single top quarks at hadron colliders. We find that a promising candidate process is gluon-gluon fusion to produce a W-boson plus technipion, with subsequent decay of the technipion to a top quark plus a bottom quark. The top-plus-bottom mode is the dominant one when the technipion mass is larger than the top mass. We calculate the total cross section and the $p_{T}$ distribution for the technipion production at Tevatron and LHC energies for a range of technipion masses, starting at 200 GeV. The decay chain of techn…
We study the contributions of the neutral pseudo Goldstone bosons (technipions and top-pions) to the t anti-t production cross sections at the Tevatron and the LHC in topcolor-assisted multiscale technicolor (TOPCMTC) models via the gluon-gluon fusion process from the loop-level couplings between the pseudo Goldstone bosons and the gluons. The MRS set A' parton distributions are used in the calculation. It is shown that the new CDF datum on the t anti-t production cross section gives constraints on the parameters in the TOPCMTC models. With reasonable values of the parameters in TOPCMTC models…
Correction to the $b\rightarrow sγ$ branching ratio in the multiscale walking technicolor model (MWTCM) is examined. For the original MWTCM, the correction is too large to explain the recent CLEO data. We show that if topcolor is further introduced, the branching ratio in the topcolor assisted MWTCM can be in agreement with the CLEO data for a certain range of the parameters.
Assuming that the observed Higgs-like resonance at the Large Hadron Collider is a technicolor isosinglet scalar (the technicolor Higgs), we argue that the standard model top-induced radiative corrections reduce its dynamical mass towards the desired experimental value. We then discuss conditions for the spectrum of technicolor theories to feature a technicolor Higgs with the phenomenologically required dynamical mass. We use scaling laws coming from modifying the technicolor matter representation, number of technicolors, techniflavors as well as the number of doublets gauged under the electrow…
The topcolor-assisted technicolor (TC2) model predicts some light pseudo goldstone bosons (PGBs), which may be accessible at the LHC or ILC. In this work we study the pair productions of the charged or neutral PGBs at the LHC and ILC. For the productions at the LHC we consider the processes proceeding through gluon-gluon fusion and quark-antiquark annihilation, while for the productions at the ILC we consider both the electron-positron collision and the photon-photon collision. We find that in a large part of parameter space the production cross sections at both colliders can be quite large co…
We present a one-doublet extended technicolor model, with all fermions in fundamental representations. The bare lagrangian has no explicit mass terms but generates masses through gauge symmetry breaking by purely QCD-like dynamics. The model generates three families of quarks and leptons and can accommodate the observed third family mass spectrum (including a large top mass and light neutrinos). In addition, we show how the model may be extended to incorporate a top color driven top mass without the need for a strong U(1) interaction. We discuss the compatiblity of the model with experimental …
In topcolor-assisted technicolor models (TC2) the hitherto unconstrained lepton flavor mixing induced by the new gauge boson $Z'$ will lead to the lepton flavor violating productions of $τ\bar μ$, $τ\bar e$ and $μ\bar e$ in photon-photon collision at the proposed International Linear Collider (ILC). Through a comparative analysis of these processes, we find that the better channels to probe the TC2 is the production of $τ\bar μ$ or $τ\bar e$ which occurs at a much higher rate than $μ\bar e$ production due to the large mixing angle and the large flavor changing coupling, and may reach the detec…
The new particles predicted by the topcolor-assisted technicolor ($TC2$) model and the littlest Higgs model with T-parity (called $LHT$ model) can induce the lepton flavor violation ($LFV$) couplings at tree level or one loop level, which might generate large contributions to some $LFV$ processes. Taking into account the constraints of the experimental data on the relevant free parameters, we calculate the branching ratios of the $LFV$ decay processes $τ^-\toμ^- P_1 P_2 $ with $P_1 P_2$ = $π^+π^-$, $K^+K^-$ and $K^0\bar{K^0}$ in the context of these two kinds of new physics models. We find tha…
We consider the contributions of the extra gauge boson Z' to the like sign $τ$ production process $e^-γ\to e^+(μ^+)τ^-τ^-$, induced by the tree-level flavor changing interactions. Since these rare production are far below the observable level in the Standard Model and other popular new physics models such as the minimal supersymmetric model, we find that Z' can give significant contributions to this process, and with reasonable values of the parameters in TC2 models, the cross section can reach several tens of fb and may be detected at the $eγ$ collisions.
Based on the effective Hamiltonian with the generalized factorization approach, we calculate the branching ratios and CP asymmetries of $B \to VV$ decays in the Topcolor-assisted Technicolor (TC2) model. Within the considered parameter space we find that: (a) for the penguin-dominated $B \to K^{*+}ϕ$ and $K^{*0}ϕ$ decays, the new physics enhancements to the branching ratios are around 40%; (b) the measured branching ratios of $B \to K^{*+} ϕ$ and $ K^{*0} ϕ$ decays prefer the range of $3 \lesssim \nceff \lesssim 5$; (c) the SM and TC2 model predictions for the branching ratio ${\cal B}(B^+ \to…
We study the constraints on models of topcolor-assisted technicolor arising from measurements of high-$E_T$ jets and high-mass lepton pairs at the Tevatron collider. Existing data can eliminate models that have appeared in the literature.
