Back to 1994-1997 ( ) 1994-1997 ( CTP) - PowerPoint PPT Presentation

Back to 1994-1997 고병원 ( 고등과학원 )

1994-1997 • 송희성 선생님 ( 서울대 CTP) • 박사과정 학생 : 이정일 , 백승원 ( 유채현 , 정동원 , 송완영 …)

Papers with Prof. Song Chiral perturbation theory versus vector meson dominance in the decays phi --> rho gamma gamma and phi --> omega gamma gamma Pyungwon Ko (Hong-Ik U.), Jungil Lee, H.S. Song (Seoul Natl. U.). Oct 1995. 11 pp. Published in Phys.Lett. B366 (1996) 287-292 Inclusive S wave charmonium productions in B decays Pyungwon Ko (Hong-Ik U.), Jungil Lee, H.S. Song (Seoul Natl. U.). Oct 1995. 12 pp. Published in Phys.Rev. D53 (1996) 1409-1415 Color octet mechanism in γ + p → J/ ψ + x Pyungwon Ko (Hong-Ik U.), Jungil Lee, H.S. Song (Seoul Natl. U.). Feb 1996. 22 pp. Published in Phys.Rev. D54 (1996) 4312-4325 Color octet heavy quarkonium productions in Z0 decays at LEP Seungwon Baek (Seoul Natl. U.), P . Ko (Hong-Ik U.), Jungil Lee, H.S. Song (Seoul Natl. U.). Jul 1996. 14 pp. Published in Phys.Lett. B389 (1996) 609-615 Color octet mechanism and J/ ψ polarization at LEP Seungwon Baek (Seoul Natl. U.), P . Ko (Hong-Ik U.), Jungil Lee, H.S. Song (Seoul Natl. U.). Jan 1997. 15 pp. Published in Phys.Rev. D55 (1997) 6839-6843 Color octet mechanism in the inclusive D wave charmonium productions in B decays Pyung-won Ko (Hong-Ik U.), Jungil Lee, H.S. Song (Seoul Natl. U.). Jan 1997. 11 pp. Published in Phys.Lett. B395 (1997) 107-112 Polarized J / psi production at CLEO Seungwon Baek (Seoul Natl. U.), P . Ko (KAIST, Taejon), Jungil Lee, H.S. Song (Seoul Natl. U.). Apr 1998. 12 pp. Published in J.Korean Phys.Soc. 33 (1998) 97-101

Chiral extensions of the SM

� One scenario: gluon fusion + diphoton decay via loop � Production: gluon fusion � Diphoton decay channel � γ � g � g � γ � Colored particle � Charged particle � It is not easy to get σ (gg →Φ New )BR( Φ New →γγ )~5 fb � Ex) Two Higgs doublet Model (Type-II) � (Angelescu, Djouadi, Moreau arxiv:1512.0492) � σ (gg → A)~850 fb × 2cot 2 β � σ (gg → H)~850 fb × cot 2 β � BR(H →γγ )~O(10 -5 ) BR(A →γγ )~O(10 -5 ) We need exotic colored and/or charged particles � Let us discuss simple case of (SM) singlet scalar boson + exotic particles �

Basic Questions • Raison d’être of (fundamental?) singlet scalar and vector- like fermions ? Completely singlet particles ??? • Uncomfortable to have a completely singlet • Two Options : Another new Higgs boson related with - New spontaneously broken gauge symmetry, or - Composite (pseudo)scalar boson • Why vector like fermions have EW scale mass ?

Answers • New chiral U(1)’ symmetry broken by new singlet scalar (Higgs) • 750 GeV excess ~ U(1)’ breaking scalar (could be even dark Higgs) • Vectorlike fermions : chiral under new U(1)’ , anomaly cancellation, and get massive by new Higgs mechanism ~ EW scale mass • Can we generate phi(750) decay width ~ 45 GeV without any conflict with the known constraints ? • Yes, if phi(750) mainly decays into new particles • Many examples : (i) Leptophobic U(1)’ with fermions in the fundamental representation of E6, (ii) anther similar 2HDM + singlet model (iii) Dark U(1)’ plus dark sector, Dark Higgs decay into a pair of Z’

A Type-II Extension has all the necessary ingredients Table 1: Matter contents in U(1) ′ model inspired by E 6 GUTs. Here, i denotes the generation index: i = 1 , 2 , 3. Z ex Fields SU(3) SU(2) U(1) Y U(1) ′ 2 Q i 1 / 6 − 1 / 3 3 2 u i 2 / 3 2 / 3 3 1 R d i − 1 / 3 − 1 / 3 3 1 R L i − 1 / 2 0 + 1 2 e i − 1 0 1 1 R n i 0 1 1 1 R H 2 − 1 / 2 0 1 2 H 1 − 1 / 2 − 1 + 1 2 0 − 1 Φ 1 1 D i − 1 / 3 2 / 3 3 1 L D i − 1 / 3 − 1 / 3 3 1 R � H i − 1 / 2 0 1 2 − L � H i − 1 / 2 − 1 1 2 R N i 0 − 1 1 1 L Fermions : 27 of E6 (!!!) Scalar Bosons : 2 Doublets + 1 Singlet

Basic Ingredients • New vectorlike fermions which are chiral under new U(1)’ : non-decoupling effects on X->gg, gam gam • Diphoton at 750 GeV = Higgs boson from U(1)’ sym breaking, mostly a SM singlet scalar • All the masses from dynamical (Higgs) mechanism • New decay modes to enhance the total decay rate cf: SU(2)H by W.C.Huang, Y.L.S.Tsai,TCYuan (2015) and applied for 750 GeV diphoton excess

Yukawa couplings The U(1) ′ -symmetric Yukawa couplings in our model are given by 1 i σ 2 Q i + y d R H 2 Q i + y e R H 2 L i + y n 1 i σ 2 L i + H.c., ij u j R H † ij d j ij e j ij n j R H † V y = y u (16) where σ 2 is the Pauli matrix. The Yukawa couplings to generate the mass terms for the extra particles are V ex = y D ij � R Φ � 1 i σ 2 � IJ � ij D j H j L H † R H 2 N j R Φ D i L + y H H i L + y N H i L + y ′ N IJ N c H i L + H.c. . (17) Complex Scalar DM One can introduce new Z ex 2 -odd scalar field X with the SU (3) C × SU (2) L × U (1) Y × U (1) H quantum numbers equal to (1 , 1 , 0; − 1). Then the gauge-invariant Lagrangian involving X is given by X 0 + λ H 1 X H † 1 H 1 + λ H 2 X H † L X = D µ X † D µ X − ( m 2 2 H 2 ) X † X − λ X ( X † X ) 2 � � Φ X ( Φ † X ) 2 + H.c. ′′ ′ − λ Φ X Φ † Φ X † X − λ Φ X | Φ † X | 2 − λ � � H R X † + H.c. ˜ LX L � y D H − dX d R D L X + y (18)

750 GeV Diphoton Excess Ko, Omura, Yu, arXiv:1601.00586 LHC13 1000 100 y � 10 � tot � 10 GeV � tot � 1 GeV Σ � pp � h � � � BR � h � �ΓΓ �� fb � Σ � pp � h � � � BR � h � �ΓΓ �� fb � y � 5 � tot � 10 GeV 1 10 0.01 0.1 y � 1 LHC13 500GeV � m f � 1TeV 10 � 4 0.001 200 400 600 800 1000 0 2 4 6 8 10 m f y

Key Aspects of the Model • Extra fermions are chiral under U(1)’, and vectorlike under the SM gauge group : this is the consequence of gauge anomaly cancellation ( 27 rep. of E 6 group) • Their masses from U(1)’ breaking > nondecoupling • U(1)’-breaking scalar produces a new singlet-like scalar h_phi ~ 750 GeV scalar boson • Decay channels of 750 GeV are determined by gauge symmetry of the underlying Type-II 2HDM with U(1)’ Higgs gauge symmetry (hh, Hh, HH, Z’Z’,DM DM etc.)

Higgs portal DM

• Dark & visible matter and dark energy, neutrinos observation expectation v ∝ r − 1 / 2 Strong gravitational lensing in Abell 1689 Jan Oort ( 1932 ) , Fritz Zwicky ( 1933 ) Bullet cluster Heights of peaks ⇒ Ω b , Ω DM Ω b ' 0 . 048 Ω DM ' 0 . 259 Ω Λ ' 0 . 691 (Planck+WP+highL+BAO) 15

Singlet Portals Baek, Ko, Park, arXiv:1303.4280, JHEP • If there is a dark sector and DM is thermal, then we need a portal to it • There are only three unique gauge singlets in the SM + RH neutrinos for Type I seesaw SM Sector Dark Sector H † H, B µ ν , N R N R ↔ e e.g. φ † X φ X , X µ ν , ψ † Hl L X φ X

DM searches @ colliders : Beyond the EFT and simplified DM models - S. Baek, P . Ko, M. Park, WIPark, C.Yu, arXiv:1506.06556, PLB (2016) - P . Ko and Hiroshi Yokoya, arXiv:1603.04737, JHEP (2016) - P . Ko, A. Natale, M. Park, H. Yokoya, arXiv:1605.07058, JHEP(2017) - P . Ko and Jinmian Li, arXiv:1610.03997, PLB (2017)

Crossing & WIMP detection Correct relic density � Efficient annihilation then Efficient production now Efficient annihilation now � � (Particle colliders) (Indirect detection) q q Efficient scattering now (Direct detection)

1 g q g χ q Γ i q ¯ ¯ φ � s ¯ q Γ i q ¯ χ Γ i χ ! χ Γ i χ Λ 2 m 2 i • Usually effective operator is replaced by a single propagator in simplified DM models • This is not good enough, since we have to respect the full SM gauge symmetry (Bell et al for W+missing ET) • In general we need two propagators, not one propagator, because there are two independent chiral fermions in 4-dim spacetime

arXiv:1605.07058 (with A. Natale, M.Park, H. Yokoya) for t-channel mediator Our Model: a ’simplified model’ of colored t -channel, spin-0, mediators which produce various mono- x + missing energy signatures (mono-Jet, mono-W, mono-Z, etc.): g W q R,L χ u L χ q R , f e Q L f Q L q R,L ¯ ¯ χ ¯ d L ¯ χ W+missing ET : special g ¯ χ χ q R,L g ¯ χ q R , f Q L e q R,L q R , f Q L e χ q R,L q R,L

1 g q g χ q Γ i q ¯ ¯ φ � s ¯ q Γ i q ¯ χ Γ i χ ! χ Γ i χ Λ 2 m 2 i • This is good only for W+missing ET, and not for other singatures • The same is also true for (scalar)x(scalar) operator, and lots of confusion on this operator in literature • Therefore let me concentrate on this case in detail in this talk

Singlet fermion CDM Baek, Ko, Park, arXiv:1112.1847 L SM � µ HS SH † H � λ HS 2 S 2 H † H mixing = L +1 S S � µ � 3 S 3 � λ S 2( ∂ µ S ∂ µ S � m 2 S S 2 ) � µ 3 S 4 S 4 invisible + ψ ( i ⇥ ∂ � m ψ 0 ) ψ � λ S ψψ decay SM H S Ψ Production and decay rates are suppressed relative to SM. This simple model has not been studied properly !! 22

Monojet+missing ET Can be obtained by crossing : s <>t m 2 m 2 1 1  � 1 125 125 ! � ⌘ Λ 3 Λ 3 s � m 2 s � m 2 Λ 3 125 + im 125 Γ 125 2 + im 2 Γ 2 col ( s ) dd dd There is no single scale you can define for collider search for missing ET