Kenneth Lane

This paper extends an earlier one describing the Higgs boson $H$ as a light composite scalar in a strong extended technicolor model of electroweak symmetry breaking. The Higgs mass $M_H$ is made much smaller than $\Lambda_{ETC}$ by tuning the ETC coupling very close to the critical value for electroweak symmetry breaking. The technicolor interaction, neglected in the earlier paper, is considered here. Its weakness relative to extended technicolor is essential to understanding the lightness of $H$ compared to the low-lying spin-one technihadrons. Technicolor cannot be completely ignored, but implementing technigluon exchange together with strong extended technicolor appears difficult. We propose a solution that turns out to leave the results of the earlier paper essentially unchanged. An argument is then presented that masses of the spin-one technifermion bound states, $\rho_H$ and $a_H$, are much larger than $M_H$ and, plausibly, controlled by technicolor. Assuming $M_{\rho_H}$ and $M_{a_H}$ are in the TeV-energy region, we identify $\rho_H$ and $a_H$ with the diboson excesses observed near $2\,{\rm TeV}$ by ATLAS and CMS in LHC Run 1 data, and we discuss their phenomenology for Runs 2 and 3.

The LHCb Collaboration’s measurement of $R_K=\mathcal{B}(B^{+}\to K^{+}{\mu }^{+}{\mu }^{-})/\mathcal{B}(B^{+}\to K^{+}{e}^{+}{e}^{-})$ lies $2.6\sigma$ below the Standard Model prediction. Several groups suggest this deficit to result from new lepton nonuniversal interactions of muons. But nonuniversal leptonic interactions imply lepton flavor violation in $B$ decays at rates much larger than are expected in the Standard Model. A simple model shows that these rates could lie just below current limits. An interesting consequence of our model, that $\mathcal{B}(B_s\to {\mu }^{+}{\mu }^{-}{)}_{\text{exp}}/\mathcal{B}(B_s\to {\mu }^{+}{\mu }^{-}{)}_{\mathrm{SM}}\cong R_K\cong 0.75$, is compatible with recent measurements of these rates. We stress the importance of searches for lepton flavor violations, especially for $B\to K\mu e$, $K\mu \tau$, and $B_s\to \mu e$, $\mu \tau$.

We suggest a criterion to minimize the amount of fine-tuning in a composite Higgs model. The paradigm of this type of model is the top-condensate model of Bardeen-Hill-Lindner. Although ``minimally fine-tuned,'' this model fails to account correctly for the masses of the top quark and the 125 GeV Higgs boson. We propose a generalization of the Bardeen-Hill-Lindner model that employs finely tuned extended technicolor plus technicolor (TC) interactions. The additional freedom of this model may accommodate both ${m}_{t}(173)$ and ${M}_{H}(125)$. This paper studies the large-${N}_{\mathrm{TC}}$ and -${N}_{C}$ limit of this model in which technicolor is weak and does not contribute to electroweak symmetry breaking. Refinements including walking-TC dynamics and a renormalization-group analysis of ${m}_{t}$ and ${M}_{H}$ will appear in a subsequent paper. A likely generic signal of this model is enhanced production of longitudinally polarized weak bosons, alone and in association with $H(125)$.

We propose a "Higgs impostor" model for the 125 GeV boson, $X$, recently discovered at the LHC. It is a technipion, $\eta_T$, with $I^G J^{PC} = 0^- 0^{-+}$ expected in this mass region in low-scale technicolor. Its coupling to pairs of standard-model gauge bosons are dimension-five operators whose strengths are determined within the model. It is easy for the gluon fusion rate $\sigma B(gg \to \eta_T \to \gamma\gamma)$ to agree with the measured one, but $\eta_T \to ZZ^*,\,WW^*$ are greatly suppressed relative to the standard-model Higgs rates. This is a crucial test of our proposal. In this regard, we assess the most recent data on $X$ decay modes, with a critical discussion of $X \to ZZ^* \to 4\ell$. In our model the $\eta_T$ mixes almost completely with the isovector $\pi^0_T$, giving two similar states, $\eta_L$ at 125 Gev and $\eta_H$ higher, possibly in the range 170--190 Gev. Important consequences of this mixing are (1) the only associated production of et al is via $\to \to W \eta_L$, and this could be sizable; (2) $\eta_H$ may soon be accessible in $gg \to \eta_H \to \gamma\gamma$; and (3) LSTC phenomenology at the LHC is substantially modified.

Under the assumption that the dijet excess seen by the CDF Collaboration near 150 GeV in $Wjj$ production is due to the lightest technipion of the low-scale technicolor (LSTC) process ${$\rho${}}_{T}$\rightarrow${}W{$\pi${}}_{T}$, we study its observability in LHC detectors for $\sqrt{s}=8\text{ }\text{ }\mathrm{TeV}$ and $$\int${}\mathcal{L}dt=20\text{ }\text{ }{\mathrm{fb}}^{-1}$. We describe interesting new kinematic tests that can provide independent confirmation of this LSTC hypothesis. We show that cuts similar to those employed by CDF, and recently by ATLAS, cannot confirm the dijet signal. We propose cuts tailored to the LSTC hypothesis and its backgrounds at the LHC that may reveal ${$\rho${}}_{T}$\rightarrow${}$\ell${}$\nu${}jj$. Observation of the isospin-related channel ${$\rho${}}_{T}^{\ifmmode\pm\else\textpm\fi{}}$\rightarrow${}Z{$\pi${}}_{T}^{\ifmmode\pm\else\textpm\fi{}}$\rightarrow${}{$\ell${}}^{+}{$\ell${}}^{-}jj$ and of ${$\rho${}}_{T}^{\ifmmode\pm\else\textpm\fi{}}$\rightarrow${}WZ$ in the ${$\ell${}}^{+}{$\ell${}}^{-}{$\ell${}}^{\ifmmode\pm\else\textpm\fi{}}{$\nu${}}_{$\ell${}}$ and ${$\ell${}}^{+}{$\ell${}}^{-}jj$ modes will be important confirmations of the LSTC interpretation of the CDF signal. The $Z{$\pi${}}_{T}$ channel is experimentally cleaner than $W{$\pi${}}_{T}$ and its rate is known from $W{$\pi${}}_{T}$ by phase space. It can be discovered or excluded with the collider data expected by the end of 2012. The $WZ$\rightarrow${}3$\ell${}$\nu${}$ channel is cleanest of all and its rate is determined from $W{$\pi${}}_{T}$ and the LSTC parameter $\mathrm{sin}{}$\chi${}$. This channel and $WZ$\rightarrow${}{$\ell${}}^{+}{$\ell${}}^{-}jj$ are discussed as a function of $\mathrm{sin}{}$\chi${}$.

Under the assumption that the dijet excess seen by the CDF Collaboration near 150 Gev in Wjj production is due to the lightest technipion of the low-scale technicolor process $\rho_T \rightarrow W \pi_T$, we study its observability in LHC detectors for 8 TeV collisions and 20 inverse femtobarns of integrated luminosity. We describe interesting new kinematic tests that can provide independent confirmation of this LSTC hypothesis. We show that cuts similar to those employed by CDF, and recently by ATLAS, cannot confirm the dijet signal. We propose cuts tailored to the LSTC hypothesis and its backgrounds at the LHC that may reveal $\rho_T \rightarrow \ell\nu jj$. Observation of the isospin-related channel $\rho^{\pm}_T \rightarrow Z \pi^{\pm}_T \rightarrow \ell^+\ell^- jj$ and of $\rho^{\pm}_T \rightarrow WZ$ in the $\ell^+\ell^-\ell^{pm}\nu_\ell$ and $\ell^+\ell^- jj$ modes will be important confirmations of the LSTC interpretation of the CDF signal. The $Z\pi_T$ channel is experimentally cleaner than $W\pi_T$ and its rate is known from $W\pi_T$ by phase space. It can be discovered or excluded with the collider data expected by the end of 2012. The $WZ \rightarrow 3\ell\nu$ channel is cleanest of all and its rate is determined from $W\pi_T$ and the LSTC parameter $\sin\chi$. This channel and $WZ \to \ell^+\ell^- jj$ are discussed as a function of $\sin\chi$.

Under the assumption that the dijet excess seen by the CDF Collaboration near 150 Gev in Wjj production is due to the lightest technipion of the low-scale technicolor process $\rho_T \rightarrow W \pi_T$, we study its observability in LHC detectors with 1--20 inverse femtobarns of data. We describe interesting new kinematic tests that can provide independent confirmation of this LSTC hypothesis. We find that cuts similar to those employed by CDF, and recently by ATLAS, cannot confirm the dijet signal. We propose cuts tailored to the LSTC hypothesis and its backgrounds at the LHC that may reveal $\rho_T \rightarrow \ell\nu jj$. Observation of the isospin-related channel $\rho^{pm}_T \rightarrow Z \pi^{pm}_T \rightarrow \ell^+ \ell^- jj$ and of $\rho^{pm}_T \rightarrow WZ$ in the three lepton plus neutrino and dilepton plus dijet modes will be important confirmations of the LSTC interpretation of the CDF signal. The $Z\pi_T$ channel is experimentally cleaner than $W\pi_T$ and its rate is known from $W\pi_T$ by phase space. It can be discovered or excluded with the collider data expected in 2012. The $WZ \rightarrow 3\ell\nu$ channel is cleanest of all and its rate is determined from $W\pi_T$ and the LSTC parameter $\sin\chi$. This channel and $WZ \rightarrow \ell^+\ell^- jj$ are discussed as a function of $\sin\chi$.