J. R. Reuter Little Higgs Models DESY, 10.6.2013 Can the 125 GeV Higgs be the Little Higgs Jürgen Reuter DESY JRR/Tonini, JHEP 1302 (2013) 077; Kilian/JRR PRD 70 (2004), 015004 LHC Physics Discussion, DESY, 10.6.2013
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Higgs as Pseudo-Goldstone boson Nambu-Goldstone Theorem: For each spontaneously broken global symmetry generator there is a massless boson in the spectrum. Old idea: Georgi/Pais, 1974; Georgi/Dimopoulos/Kaplan, 1984 Light Higgs as (Pseudo)-Goldstone boson of a spontaneously broken global symmetry Λ O (1 GeV) Analogous: QCD Scale Λ : chiral symmetry breaking, quarks, SU p 3 q c v Scale v : pions, kaons, . . . O (150 MeV)
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Higgs as Pseudo-Goldstone boson Nambu-Goldstone Theorem: For each spontaneously broken global symmetry generator there is a massless boson in the spectrum. Old idea: Georgi/Pais, 1974; Georgi/Dimopoulos/Kaplan, 1984 Light Higgs as (Pseudo)-Goldstone boson of a spontaneously broken global symmetry Λ O (1 TeV) Scale Λ : global symmetry breaking, new particles, new (gauge) IA Scale v : Higgs, W { Z , ℓ ˘ , . . . v O (250 GeV) Without Fine-Tuning: experimentally excluded
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Collective symmetry breaking and 3-scale models Collective symmetry breaking: Arkani-Hamed/Cohen/Georgi/Nelson/. . . , 2001 2 different global symmetries; one of them unbroken ñ Higgs exact Goldstone boson Coleman-Weinberg: boson masses by radia- m H „ g 1 g 2 4 π Λ tive corrections, but: m H only at 2-loop level 4 π Λ O (10 TeV) Scale Λ : global SB, new IA Scale F : Pseudo-Goldstone F O (1 TeV) bosons, new vectors/fermions v Scale v : Higgs, W { Z , ℓ ˘ , . . . O (250 GeV)
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Characteristics and Spectra Scale Λ : “hidden sector”, Λ O ( � 10 TeV) symmetry breaking O (1 TeV) F Scale F : new particles v O (250 GeV) Scale v : h , W { Z , ℓ ˘ , . . . Terascale: new particles to stabilize the hierarchy M [TeV] q L ˜ ˜ Little Higgs SUSY t 2 ˜ b 2 Φ q R ˜ ˜ Φ ±± b 1 1 . 25 Φ ± ˜ Z ′ t 1 T W ′ ± 1 . 00 Φ P g ˜ U, C 0 . 75 γ ′ χ ± χ 0 H ± ˜ 4 , ˜ H, A 2 χ 0 ˜ 0 . 50 3 τ 2 ˜ χ ± χ 0 2 , ˜ ˜ ˜ h ℓ L 1 ˜ ν ℓ 0 . 25 t ˜ t ℓ R τ 1 ˜ η h χ 0 ˜ W ± Z 1
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Generic properties of Little-Higgs models – Extended global symmetry (extended scalar sector) – Specific functional form of the potential – Extended gauge symmetry: γ 1 , Z 1 , W 1 ˘ – New heavy fermions: T , but also U, C, . . . Product Group Models Simple Group Models (e.g. Littlest Higgs) (e.g. Simplest Little Higgs) H → H ′ H 1 → H ′ H 2 → H ′ 1 2 H 1 ∋ h ∈ H 2 G 1 → G ′ G 2 → G ′ [ H 1 , H 2 ] � = 0 1 1 g 1 � = 0 g 2 � = 0 G diag → G ′ / / H 1 ⊂ H H 2 ⊂ H
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Generic properties of Little-Higgs models – Extended global symmetry (extended scalar sector) – Specific functional form of the potential – Extended gauge symmetry: γ 1 , Z 1 , W 1 ˘ – New heavy fermions: T , but also U, C, . . . Product Group Models Moose Models (e.g. Littlest Higgs) (e.g. Minimal Moose Model) H → H ′ H 1 / H 2 / H 3 / H 4 / H 5 / • • • H n / G 1 → G ′ G 2 → G ′ [ H 1 , H 2 ] � = 0 1 1 g 1 � = 0 g 2 � = 0 / / H 1 ⊂ H H 2 ⊂ H G 1 / / G 2 / G 3 G 4 / • • • / G n
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Little Higgs Models Plethora of “Little Higgs Models” in 3 categories: § Moose Models § Orig. Moose (Arkani-Hamed/Cohen/Georgi, 0105239) § Simple Moose (Arkani-Hamed/Cohen/Katz/Nelson/Gregoire/Wacker, 0206020) § Linear Moose (Casalbuoni/De Curtis/Dominici, 0405188) § Simple (Goldstone) Representation Models § Littlest Higgs (Arkani-Hamed/Cohen/Katz/Nelson, 0206021) § Antisymmetric Little Higgs (Low/Skiba/Smith, 0207243) § Custodial SU p 2 q Little Higgs (Chang/Wacker, 0303001) § Littlest Custodial Higgs (Chang, 0306034) § Little SUSY (Birkedal/Chacko/Gaillard, 0404197) § Simple (Gauge) Group Models § Orig. Simple Group Model (Kaplan/Schmaltz, 0302049) § Holographic Little Higgs (Contino/Nomura/Pomarol, 0306259) § Simplest Little Higgs (Schmaltz, 0407143) § Simplest Little SUSY (Roy/Schmaltz, 0509357) § Simplest T parity (Butenuth/JRR, 2010)
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Varieties of Particle spectra SO p 5 q , G “ r SU p 2 q ˆ U p 1 qs 2 Sp p 6 q , G “ r SU p 2 q ˆ U p 1 qs 2 H “ SU p 5 q H “ SO p 6 q SU p 2 q ˆ U p 1 q SU p 2 q ˆ U p 1 q Arkani-Hamed/Cohen/Katz/Nelson, 2002 Low/Skiba/Smith, 2002 Z ′ Z ′ m m Φ W ′ ± W ′ ± B ′ Φ ±± Φ P Φ ± T T Φ Φ P B ′ A H ± H t t h h Z Z W ± W ± H “ r SU p 3 qs 2 m r SU p 2 qs 2 , G “ SU p 3 q ˆ U p 1 q W ′ ± ù ñ Z ′ SU p 2 q ˆ U p 1 q X 0 /Y 0 T Schmaltz, 2004 r SU p 4 qs 4 Ñ r SU p 3 qs 4 U, C § Kaplan/Schmaltz, 2003 h 2 HDM , h 1 { 2 , Φ 1 1 , 2 , 3 , Φ 1 P 1 , 2 , 3 , t η Z Z 1 1 ,..., 8 , W 1 ˘ 1 , 2 , q 1 , ℓ 1 W ±
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Effective Dim. 6 Operators JJ “ 1 O p I q F 2 tr r J p I q ¨ J p I q s Ý Ñ ——————————————————————————————— ´ v 2 O 1 1 ` p Dh q : h ˘ ` h : p D h q ˘ 2 | Dh | 2 “ ¨ h, 1 F 2 Ý Ñ F 2 p h : h ´ v 2 { 2 q p Dh q : ¨ p Dh q O 1 1 “ hh ——————————————————————————————— h, 3 “ 1 1 O 1 3 p h : h ´ v 2 { 2 q 3 Ý Ñ F 2
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Ý Ñ W W “ ´ 1 1 O 1 2 p h : h ´ v 2 { 2 q tr W µν W µν F 2 O B “ 1 i 2 p D µ h q : p D ν h q B µν F 2 BB “ ´ 1 1 O 1 4 p h : h ´ v 2 { 2 q B µν B µν F 2 ——————————————————————————————— 1 Ý Ñ O V q “ F 2 qh p { Dh q q
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Constraints on LHM Constraints from contact IA: ( f p 3 q JJ , f p 1 q 4 . 5 TeV À F { c 2 10 TeV À F { c 1 2 JJ ) c, c 1 ! 1 ✸ Constraints evaded ð ñ B 1 , Z 1 , W 1 ˘ superheavy ( O p Λ q ) decouple from fermions ∆ S , ∆ T in the Littlest Higgs model, violation of Custodial SU(2): Csáki et al., 2002; Hewett et al., 2002; Han et al., 2003; Chen/Dawson, 2003; Kilian/JRR, 2003 ∆ S 2 v 2 λ 2 ” c 2 p c 2 ´ s 2 q ` 5 c 1 2 p c 1 2 ´ s 1 2 q ı v 2 v 2 Á v 2 α ∆ T Ñ 5 2 φ 8 π “ ´ F 2 Ñ 0 F 2 ´ g 2 g 1 2 4 M 4 F 2 φ General models § Triplet sector: (almost) identical to Littlest Higgs ( ∆ S only) § More freedom in U p 1 q sector: ( ∆ T )
J. R. Reuter Little Higgs Models DESY, 10.6.2013 T parity and Dark Matter Cheng/Low, 2003; Hubisz/Meade, 2005 § T parity: T a Ñ T a , X a Ñ ´ X a , automorphism of coset space analogous to R parity in SUSY, KK parity in extra dimensions § Bounds on F MUCH relaxed, F „ 1 TeV but: Pair production!, typical cascade decays § Lightest T -odd particle (LTP) ñ Candidate for Cold Dark Matter
J. R. Reuter Little Higgs Models DESY, 10.6.2013 T parity and Dark Matter Cheng/Low, 2003; Hubisz/Meade, 2005 § T parity: T a Ñ T a , X a Ñ ´ X a , automorphism of coset space analogous to R parity in SUSY, KK parity in extra dimensions § Bounds on F MUCH relaxed, F „ 1 TeV but: Pair production!, typical cascade decays § Lightest T -odd particle (LTP) ñ Candidate for Cold Dark Matter f M (GeV) A H 108 144 180 216 252 288 Littlest Higgs: A 1 LTP 500 W 1 , Z 1 „ 650 GeV, Φ „ 1 TeV 400 T, T 1 „ 0.7-1 TeV M H (GeV) 300 Annihilation: A 1 A 1 Ñ h Ñ WW, ZZ, hh Hubisz/Meade, 2005 200 0/10/50/70/100 100 600 800 1000 1200 1400 1600 1800 2000 f (GeV)
J. R. Reuter Little Higgs Models DESY, 10.6.2013 T parity and Dark Matter Cheng/Low, 2003; Hubisz/Meade, 2005 § T parity: T a Ñ T a , X a Ñ ´ X a , automorphism of coset space analogous to R parity in SUSY, KK parity in extra dimensions § Bounds on F MUCH relaxed, F „ 1 TeV but: Pair production!, typical cascade decays § Lightest T -odd particle (LTP) ñ Candidate for Cold Dark Matter f M (GeV) A H 108 144 180 216 252 288 Littlest Higgs: A 1 LTP 500 W 1 , Z 1 „ 650 GeV, Φ „ 1 TeV 400 T, T 1 „ 0.7-1 TeV M H (GeV) 300 Annihilation: A 1 A 1 Ñ h Ñ WW, ZZ, hh Hubisz/Meade, 2005 200 0/10/50/70/100 100 600 800 1000 1200 1400 1600 1800 2000 f (GeV) § T parity Simplest LH: Pseudo-Axion η LTP Z 1 remains odd: good or bad (?) Kilian/Rainwater/JRR/Schmaltz § T parity might be anomalous (???) Hill/Hill, 2007
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Reach in the gauge boson sector: depends on mixing angle
J. R. Reuter Little Higgs Models DESY, 10.6.2013 Motivation How to constrain a generic model in HEP ? § direct searches of resonances § electroweak precision tests § flavour constraints § nowadays: Higgs sector Higgs sector is the key to understand EW-scale physics (and beyond?)
Recommend
More recommend
