Walking Technicolor in light of LHC-Run II Shinya Matsuzaki Department of Physics & Institute for Advanced Research, Nagoya U. Collaborators: M.Kurachi, K.Yamawaki (KMI, Nagoya U) K.Terashi (Tokyo U) (involving works in progress) References: S.M. and K. Yamawaki, PRD85, 86, 86 (‘12), PRD87(‘12), PLB719(‘13), 1304.4882 (proc. of SCGT12), PRD90(‘14), PRD90(‘14), PRL113(‘14), and works in progress @ Toyama Univ. 12/05/2014
1. Introduction Current status on 125 GeV Higgs discovered at LHC CMS-PAS-HIG-14-009 ATLAS-CONF-2014-009 * measured coupling properties consistent w/ the SM Higgs so far * BUT, is it really the SM Higgs? --- origin of mass put in by hand? --- unnatural elementary Higgs?
It could be a composite scalar, “Technidilaton (TD)” Yamawaki et al (‘86); Bando et al (‘86) * TD = a composite scalar: -- predicted in walking technicolor (WTC) giving dynamical origin of mass by technifermion condensate -- arises as a pNGB for SSB of QCD-like “walking” (approximate) scale symmetry technifermion condensate ~1000TeV ~ O(4 π Fπ) = O(1TeV) -- lightness protected by the scale symmetry and hence can be, say, ~ 125 GeV. LatKMI Collaboration, PRD89(‘14) S.M. and K.Yamawaki, PRD86 (‘12) * 125 GeV TD signatures at LHC are consistent with S.M. and K. Yamawaki, PRD85,86 (‘12), PLB719 (‘13); current data S.M. 1304.4882; talk at SCGT14mini and PPP (‘14)
The idea of technicolor (TC) * SU(3)c x SU(2 )L x U(1) Y invariant gauge kin. fermion kin. Yukawa Higgs
The idea of technicolor (TC) * SU(3)c x SU(2 )L x U(1) Y invariant Unnatural Higgs dynamics replaced by natural gauge dynamics gauge kin. Extended TC fermion kin. Yukawa Higgs New color dynamics, Technicolor (TC)
Dynamical EWSB by technicolor Susskind (‘79);Farhi-Susskind(‘85) * A typical TC model: one-family (Farhi-Susskind) model * Q: techniquarks * L: technileptons replaced by (+ ETC-induced term) SU(N TC ) gauge theory w/ 8 techni-flavors
* SU(N TC )(vector-like) gauge theory breaks the chiral symmetry as in QCD QCD-like SSB α gets strong at the IR scale =O(EW)
* SU(N TC )(vector-like) gauge theory breaks the chiral symmetry as in QCD QCD-like SSB α gets strong at the IR scale =O(EW) 63 composite NGBs emerge and
* SU(N TC )(vector-like) gauge theory breaks the chiral symmetry like QCD QCD-like SSB α gets strong at the IR scale =O(EW) subgroup includes EW SU(2) x U(1) in the SM :technipion decay const. # of EW doublets Dynamical W,Z mass-generation W,Z W,Z Dynamical explanation of origin of EWSB and W,Z masses
* SU(N TC )(vector-like) gauge theory breaks the chiral symmetry like QCD QCD-like SSB α gets strong at the IR scale =O(EW) SM gauge turned on: SU(3) x SU(2) x U(1) breaks the global sym. 60 get massive (technipions), 3 eaten by W & Z Main source SU(3) “ETC”
* SU(N TC )(vector-like) gauge theory breaks the chiral symmetry like QCD QCD-like SSB α gets strong at the IR scale =O(EW) 63 composite vector mesons (technirhos) emerge In addition,
SM fermion mass generation by “Extended TC” ETC1 ETC2 ETC3 F F ETCi Dynamical explanation of Yukawa interaction!
Thus, TC provides: * dynamical origin of Higgs potential (mechanism of EWSB) --- everything can be explained by gauge principle * solution of naturalness problem/hierarchy problem * rich spectra (techni-hadrons; technipions & technirhos) at O(TeV) Theoretically, TC is much better than SM!!
However, TC should not be QCD-like at all * QCD-like TC was phenomenologically QCD-like killed 3 times !! 2 nd 2 nd No symmetry to protect the lightness
However, TC should not be QCD-like at all * Walking TC can be viable, solve problems QCD-like by which QCD-like TC was killed: Yamawaki,Bando, 2 nd 2 nd Matumoto (‘86) Haba, Matsuzaki, Yamawaki (‘08,’10,) Matsuzaki, Yamawaki (‘12,’13) No symmetry to protect the lightness “Technidilaton”
Contents of this talk: 1. Introduction 2. Walking TC and Technidilaton (TD) 3. 125 GeV TD signal vs. current LHC data 4. Discovering walking technipions and technivector mesons 5. Summary
2. Walking technicolor (WTC) and technidilaton (TD)
A schematic view of walking TC * all things related to the dynamics characterized by a single scale QCD-like -- spontaneous chiral sym. breaking --- hadron masses --- explicit scale sym.breaking (violent running coupling)
A schematic view of walking TC * all things related to the dynamics characterized by a single scale QCD-like -- spontaneous chiral sym. breaking --- hadron masses --- explicit scale sym.breaking (violent running coupling) deform QCD-like QCD-like
A schematic view of walking TC * all things related to the dynamics characterized by a single scale QCD-like -- spontaneous chiral sym. breaking --- hadron masses --- explicit scale sym.breaking (violent running coupling) QCD-like * Theory divided into two scale regions: “walking” QCD-like between them, the coupling is slowly running ( walking ): approximately scale-invariant
region (II) region (I) -- spontaneous chiral sym. breaking at QCD-like --- hadron masses characterized by “walking” the IR scale (chiral breaking scale) QCD-like --- two types of scale sym.breaking I) explicitly broken due to QCD-like (perturbative) running characterized by II) spontaneously broken due to the dynamical mas generation Until the scale mF, the theory is approximately scale-invariant (hard-breaking washed out)
region (II) region (I) -- spontaneous chiral sym. breaking at QCD-like --- hadron masses characterized by “walking” the IR scale (chiral breaking scale) QCD-like --- two types of scale sym.breaking I) explicitly broken due to QCD-like (perturbative) running characterized by α starts “running” (walking) up to mF Until the scale mF, the theory is approximately scale-invariant (hard-breaking washed out) “Miransky scaling” (Miransky (1985)) II) spontaneously broken due to the dynamical mas generation Simultaneously, explicitly broken
* A composite Higgs(~FFbar) = Technidilaton (TD) emerges as (p)NGB for approx. scale symmetry QCD-like “walking” QCD-like ii) spontaneously broken due to the dynamical mas generation Simultaneously, explicitly broken SSB of (approximate) scale sym . α starts “running” (walking) up to mF Nonpert. scale anomaly induced by mF itself TD gets massive
Historically, Be “Walking” Holdom (1981); Yamawaki et al (1986); Bando et al (1986); Akiba et al (1986); Appelquist et al (1986); (1987) to solve FCNC problem The explicit proposal based on ladder SD eq analysis of scale-invariant/standing strong QED Yamawaki et al (1986); Bando et al (1986)
* What would be like a realistic walking gauge theory? QCD-like “walking” QCD-like Note presence of pseudo FP :Pseudo FP β “walking”
A candidate for the walking gauge theory * QCD with many flavors (large Nf QCD) Large fermionic Nf balances with gluonic Nc to realize walking!
* Search for walking TC by lattice simulations Slide from Yamazaki’s talk at PPP2014
* Search for walking TC by lattice simulations Slide from Yamazaki’s talk at PPP2014 one-family model may be walking!
Light techni-dilaton(i) * A straightforward nonpert. calc. of large Nf QCD in the ladder approximation Kurachi et al,(‘06) implies the tendency of lightness for the TD (even in the ladder approximation)
Light techni-dilaton(ii) S.M and K.Yamawaki , PRD86 (2012) * One suggestion from holographic formula for TD mass --- TD mass (lowest pole of dilatation current correlator) “conformal limit” 125 GeV TD is realized by a large gluonic effect : G 〜 10 for one- family model w/ Fπ = 123 GeV (c.f. QCD case, G ~ 0.25 ) 125 GeV
113 (2014) 113 (2014) Light techni-dilaton(iii) Conclusive answer will be given by lattice simulations Slide from Yamazaki’s talk at PPP2014
3. 125 GeV TD Signal vs. LHC-Run I Data
TD Lagrangian below m F S.M. and K. Yamawaki, PRD86 (2012) * effective theory below mF walking regime after TF decoupled/integrated out & confinement : governed by TD and other light TC hadrons * Nonlinear realization of scale and ~O(TeV) chiral symmetries Nonlinear base χ for scale sym. w/ TD field Φ associated decay constant F Φ Nonlinear base U for chiral sym. w/ TC pion field π
eff. TD Lagrangian i) The scale anomaly-free part: ii) The anomalous part (made invariant by including spurion field “S”): reflecting ETC-induced TF 4-fermi w/ (3- γ m ) β F : TF-loop contribution iii) The scale anomaly part: t0 beta function which correctly reproduces the underlying scale anomaly (PCDC relation):
TD couplings to the SM particles * TD couplings to W/Z boson (from L_inv) * TD couplings to γγ and gg (from L_S) β F : TF-loop contribution t0 beta function
TD couplings to the SM particles * TD couplings to W/Z boson (from L_inv) The same form as SM Higgs couplings * TD couplings to γγ and gg (from L_S) except F Φ and betas β F : TF-loop contribution t0 beta function
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