Light scalar at the high energy and intensity frontiers: example in the minimal left-right model

Size: px

Start display at page:

Download "Light scalar at the high energy and intensity frontiers: example in the minimal left-right model"

Marion Henry
5 years ago
Views:

Light scalar at the high energy and intensity frontiers: example in the minimal left-right model Yongchao Zhang («[ ) Université Libre de Bruxelles ( Washington University in St.

1 Light scalar at the high energy and intensity frontiers: example in the minimal left-right model Yongchao Zhang («[ ) Université Libre de Bruxelles ( Washington University in St. Louis) Aug 11, 2017, Columbus Ohio TeVPA 2017 based on Bhupal Dev, Mohapatra & YCZ, NPB [ ] Bhupal Dev, Mohapatra & YCZ, PRD95, [ ] Bhupal Dev, Mohapatra & YCZ, JHEP05(2016)174 [ ]

2 Long-lived particle & the HEP frontiers LLPs are intimately related to the frontiers of HEP: [see the MATHUSLA white paper 17xx.abcde] neutrino masses, DM, baryon asymmetry, naturalness, supersymmetry, composite models, leptogenesis... The world is chiral: weak interaction is left-handed. since the era of C.N.Yang, T.D.Lee & C.S.Wu... EW theory LRSM light scalar: unique LLP candidate Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

3 Minimal Left-Right Symmetric Model Minimal left-right symmetric extension: SU(2) L U(1) Y SU(2) L SU(2) R U(1) B L Matter fields are parity symmetric left-handed right-handed ) ( ) ur = Q d L Q R = L d R ) ( ) NR = Ψ e L Ψ R = L e R ( ul ( νl There are three different classes of LR models (private communication with Mohapatra), here is the best-known scenario Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

4 Minimal scalar sector Pati & Salam 74; Mohapatra & Pati 75; Senjonavić & Mohapatra 75 SU(2) L SU(2) R U(1) B L R (1, 3, 2) R (1, 3, 2) SU(2) L U(1) Y Φ (2, 2, 0) Φ (2, 2, 0) U(1) EM ( R ++ R 0 R R ( φ 0 1 φ + 2 φ 1 φ 0 2 ) H 3 (CP-even) ) h, H 0 1, A 0 1, H ± 1 }{{} heavy doublet Left-handed triplet L decouples from the TeV scale physics. [Chang, Mohapatra & Parida 84, Deshpande, Gunion, Kayser & Olness 91] Gauge coupling g R g L at the TeV scale. Assuming CP conservation and the parameters small: [Zhang, An, Ji & Mohapatra 07, Dev, Mohapatra & YCZ 16] ξ φ 0 2 / φ0 1 = κ /κ m b /m t 1, ɛ v EW /v R = κ 2 + κ 2 /v R 1 Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

5 Physical scalars Bidoublet scalar Φ L Y = h Q L ΦQ R + h Q L ΦQR ( Φ = σ 2 Φ σ 2 ) EW symmetry breaking, generating fermion masses SM-like Higgs: h Re φ 0 1 Heavy doublet H 0 1, A 0 1, H + 1 (φ0 2, φ + 2 ) [Mohapatra et al, 83; Ecker et al, 83; Pospelov, 97; Zhang et al, 07; Maiezza et al, 10; Chakrabortty et al, 12; Bertolini et al, 14] RH triplet: H 3 Re 0 R tree level FCNC couplings to the quarks M φ2 15 TeV SU(2)R -breaking coupling to W R coupling to RHNs type-i seesaw mechanism L Y = f Φ T R R Φ R (Almost) no lower limits on its mass can be very light! [Nemevsek et al, 12; Maiezza et al, 16; Nemevsek et al, 16; Dev, Mohapatra & YCZ, , xxxx.yyyyy] cosmological + supernova constraints m H3 MeV Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

6 How could it be so light ( GeV)? At tree level... At the leading order [mixing constrained to be very small] V ρ 1 [Tr( R R )]2 m 2 H 3 4ρ 1 v 2 R Mixing with the SM Higgs [note the inverse dependence on the VEV ratio] ( ) 4λ1 ɛ 2 2α 1 ɛ v 2α 1 ɛ 4ρ R 2 = sin θ 1 α 1 v R 1 2λ 1 v EW Mixing with the heavy doublet scalar H 1 [inducing FCNC couplings] sin θ 2 4α 2 α 3 v EW v R Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

7 How could it be so light ( GeV)? At tree level... Mass dependence on the quartic couplings at the tree level m 2 H 3 4ρ 1 v 2 R sin 2 θ 1 m 2 h, -2-3 log 10 α theoretical limit M H3 > MeV 10 MeV 100 MeV 1 GeV 10 GeV 100 GeV log 10 ρ 1 To have a GeV H 3, the parameter ρ 1 GeV 2 /4v 2 R 10 8 for v R = 5 TeV. Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

8 How could it be so light ( GeV)? At 1-loop level... Mass dependence on the parameters at the 1-loop level ( m 2 H3 ) loop 3 2π 2 [ 1 3 α ρ2 2 8f g 4 R + (g 2 R + g 2 BL) 2 ] v 2 R H3 H3 H3 H3 Φ Φ vr vr vr vr H3 H3 H3 H3 H3 H3 V R V R N i vr vr vr vr vr vr For m H3 GeV and v R few TeV, the parameters above are tuned at the level of GeV/ v R 4π Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

9 Decay LLP candidate! Couplings to SM quarks and leptons are proportional to sin θ 1,2. H 3 γγ suppressed by the heavy particle masses, effectively by v R scale. Γ(H 3 q q) sin θ 2 1,2, Γ(H 3 l + l ) sin θ 2 1,2, Γ(H 3 gg) sin θ1,2 2 (loop factor), Γ(H 3 γγ) = α2 mh vR π3 }{{} 3 W R loop }{{} H ± 1 loop 4 3 }{{} H ±± 2 loop 2. Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

10 proper Lifetime log 10 sin θ km 100 m 10 m 1 m 10 cm 1 cm 0.1 cm log 10 [m H3 /GeV] log 10 sin θ km 100 m 10 m 1 m 10 cm 1 cm 0.1 cm log 10 [m H3 /GeV] v R = 5 TeV, m H3 = 1 GeV cτ 0 cm Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

11 FCNC couplins K, B meson mixing Effective FCNC coupling for K 0 K 0 mixing from mixing with heavy doublet scalar H 1 and SM Higgs h L H3 = G F 4 sin 2 θ2 2 m 2 K m2 + im H H3 Γ H3 3 [ ( i m i λ RL i ) 2 O 2 + ( sin θ 2 sin θ 2 + ξ sin θ 1, i m i λ LR i ) 2Õ2 + 2( i m i λ LR i [ξ = φ 0 2 / φ0 1, h H1 mixing ] )( i ] m i λ RL i )O 4 O 2 = [ s(1 γ 5)d][ s(1 γ 5)d], Õ 2 = [ s(1 + γ 5)d][ s(1 + γ 5)d], O 4 = [ s(1 γ 5)d][ s(1 + γ 5)d]. m i = {m u, m c, m t}, λ LR i = V L,i2 V R,i1, λ RL i = V R,i2 V L,i1 Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

12 FCNC couplins K, B meson flavor-changing decay d, s (d) b (s) H 3 l + (hadron, γ) l (hadron, γ) H 3 decaying inside detector spatial resolution or outside detector size Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

13 flavor limits: high intensity frontier Expt. meson decay H 3 decay E H3 L H3 BR/N event NA48/2 [ 09] K + π + H 3 H 3 e + e 30 GeV < 0.1 mm NA48/2 [ 11] K + π + H 3 H 3 µ + µ 30 GeV < 0.1 mm NA62 [ 14] K + π + H 3 H 3 γγ 37 GeV < 0.1 mm E949 [ 09] K + π + H 3 any (inv.) 355 MeV > 4 m NA62 [ 05] K + π + H 3 any (inv.) 37.5 GeV > 2 m KTeV [ 03] K L π 0 H 3 H 3 e + e 30 GeV < 0.1 mm KTeV [ 00] K L π 0 H 3 H 3 µ + µ 30 GeV < 0.1 mm KTeV [ 08] K L π 0 H 3 H 3 γγ 40 GeV < 0.1 mm BaBar [ 03] B KH 3 H 3 l + l m B /2 < 0.1 mm Belle [ 09] B KH 3 H 3 l + l m B /2 < 0.1 mm LHCb [ 12] B + K + H 3 H 3 µ + µ 150 GeV < 0.1 mm BaBar [ 13] B KH 3 any (inv.) m B /2 > 3.5 m Belle II [ 10] B KH 3 any (inv.) m B /2 > 3 m LHCb [ 17] B s µµ BaBar [ 10] B d γγ Belle [ 14] B s γγ BaBar [ 11] Υ γh 3 H 3 qq, gg m Υ /2 < 3.5 m [1, 80] 10 6 CHARM [ 85] K πh 3 H 3 γγ 10 GeV [480, 515] m < 2.3 CHARM [ 85] B X s H 3 H 3 γγ 10 GeV [480, 515] m < 2.3 SHiP [ 15] K πh 3 H 3 γγ 25 GeV [70, 125] m < 3 SHiP [ 15] B X s H 3 H 3 γγ 25 GeV [70, 125] m < 3 DUNE [ 13] K πh 3 H 3 γγ 12 GeV [500, 507] m < 3 DUNE [ 13] B X s H 3 H 3 γγ 12 GeV [500, 507] m < 3 future prospects, flavor-conserving couplings only Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

14 Example: B meson limits sin θ cosmological limits BaBar B width [excl.] 100 m Belle B Kν ν Belle II LHCb 1 m Bs μ + μ - Bs mixing Bd mixing cm 0.01 cm sin θ cosmological limits Bd γγ Bs γγ BaBar B width [excl.] 100 m Belle B Kν ν Belle II LHCb 1 m Bs μ + μ - Υ γh 3 Bs mixing Bd mixing B d(s) B d(s) mixing limits from CKM fitter [9.3 (2.7) 10 11(9) MeV] [Charles et al 15] B width limits from 20% of Γ total (B) B Kl + l : BaBar [ 03], Belle [ 09], LHCb [ 12] B Kν ν : BaBar [ 13], Belle II (prospects) B s µ + µ : LHCb [ 17] B d(s) γγ : BaBar (Belle) [ 10 ( 14)] Υ γh 3 : BaBar [ 11] (dashed gray lines indicate the proper lifetime of H 3) Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20 1 cm 0.01 cm

15 Beam dump experiments high intensity frontier sin θ cosmological limits B width [incl.] K ± width CHARM [B] DUNE [B] SHiP [B] SHiP [K] CHARM [K] DUNE [K] KL width sin θ cosmological limits B width [incl.] K ± width KL width CHARM [B] DUNE [B] SHiP [B] SHiP [K] CHARM [K] DUNE [K] 100 m 1 m 1 cm 0.01 cm m 1 m 1 cm 0.01 cm CHARM : N PoT = = K, B SHiP : N PoT = = K, B DUNE : N PoT = = K, B Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

16 LHC high energy frontier SM Higgs portal, highly suppressed by sin θ 1. Gauge portal, associate production with W R : q W R q j q W R H 3 q W R W R H 3 j (subleading) For light scalar m H3 10 GeV, the production cross section is almost a constant σ(pp H 3 jj) = (7.2)1.6[0.15] fb, for g R /g L = (0.6)1.0[1.5] Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

17 Unique displaced photon signal Number of Events MATHUSLA LHC s = 14 TeV 3000 fb -1 The mixing angles sin θ 1,2 are constrained to be very small ( 10 4 ) by the meson data. H 3 γγ, highly collimated diphoton signal, dominated by the W R loop, suppressed by v R. H 3 tends to be long-lived if it is light. Decaying inside the ECAL of ATLAS, with 1 cm < bcτ 0 < 1.5 m (boost factor b 10 2 ). MATHUSLA is senstive to lighter and longer-lived H 3. [see the talk by David Curtin] Unique (smoking-gun?) signal of the LR model: In generic models the extra light scalar decays mostly into the SM fermions through mixing with the SM Higgs displaced photon + high-p T jets without large /E }{{} T from W R decay Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

18 Probable m H3 M WR regions 8 7 LHC [0.6] LHC [1.0] LHC [1.5] MATHUSLA [0.6] MATHUSLA [1.0] MATHUSLA [1.5] s = 14 TeV 3000 fb -1 M WR [TeV] m 1 m 1 cm 0.01 cm LHC: Assuming 10 LLP signal events. MATHUSLA: Assuming 4 signal events. Effective solid angle very small, 10%. Thin -disk-like compared to the decay length of 100 m. Larger regions probable at FCC-hh and forward LLP detectors therein. Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

19 Complementarity of the high energy/intensity experiments sin θ cosmological limits B Kχχ K πχχ B Kν ν Belle II K + π + νν NA62 CHARM [B] SHiP [B] CHARM [K] DUNE [K] Bs mixing K 0 mixing Bd mixing MATHUSLA FCC forward detector LHC LLP searches FCC LLP searches sin θ cosmological limits B Kχχ K πχχ B Kν ν Belle II K + π + νν NA62 CHARM [B] SHiP [B] CHARM [K] DUNE [K] Υ γh 3 Bs mixing K 0 mixing Bd mixing MATHUSLA FCC forward detector LHC LLP searches FCC LLP searches The LLP searches at LHC & MATHUSLA are largely complementary to the meson limits H 3 mass ranges complementary. Mixing angles sin θ 1,2 complementary. (H 3 γγ does not depend on sin θ 1,2 ) With the future 100 TeV collider we can do better... Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

20 Conclusion: take-away messages In the minimal left-right symmetric model, the SU(2) R -breaking scalar H 3 could be light and long-lived. The mixings with SM Higgs and heavy doublet scalar are constrained (mainly by meson data) to be very small, The singlet-like scalar H 3 are produced at LHC from gauge interaction (associate production with W R ) and decays predominantly into γγ. It could be tested at the high itensity experiments like DUNE and SHiP. It could also be probable via displaced photon searches at both ATLAS/CMS and MATHUSLA. The high-energy and high-intensity frontier of left-right models are largely complementary to each other, and provide us a new way to understand the neutrino masses, parity breaking etc. Thank you for your attention! Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

21 backup slides

22 Branching ratios log10 BR -3 log10sin θ H3 ℓ + ℓ - H3 γγ H3 gg H3 qq log10 [mh3 /GeV] Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

23 Branching ratios log 10 BR log 10 sin θ H 3 l + l - H 3 γγ H 3 qq H 3 gg log 10 [m H3 /GeV] Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

24 K ± meson limits sin θ cosmological limits K ± width K + π + νν [NA62] 100 m 1 m K + π + e + e - K + π + μ + μ - K + π + γγ 0.01 cm 1 cm sin θ cosmological limits K ± width limits from 20% of Γ total (K ± ) K ± width K + π + νν [NA62] K + π + e + e - K + π + μ + μ - K + π + γγ 100 m 1 m K ± π ± e + e : NA48/2 [ 09] K ± π ± ν ν : E949 [ 09] K ± π ± µ + µ : NA48/2 [ 11] K ± π ± ν ν : NA62 (prosepcts) K ± π ± γγ : NA62 [ 14] (dashed gray lines indicate the proper lifetime of H 3) 0.01 cm 1 cm Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

25 K 0 meson limits 1 1 sin θ cosmological limits KL π 0 γγ K 0 mixing KL width 100 m 1 m KL π 0 e + e - KL π 0 μ + μ cm 1 cm sin θ cosmological limits KL π 0 γγ K 0 mixing KL width KL π 0 e + e - KL π 0 μ + μ m 1 m K 0 K 0 mixing limits from 50% of experimental central value [ MeV] (large theoretical uncertainties) K L width limits from 20% of Γ total (K L ) K L π 0 e + e : KTeV [ 03] K L π 0 µ + µ : KTeV [ 00] K L π 0 γγ : KTeV [ 08] (dashed gray lines indicate the proper lifetime of H 3) 0.01 cm Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20 1 cm

26 Higgs measurements and rare Z decay Higgs inv. [LHC] Z γh 3 sin θ cosmological limits [ILC] K width B width [incl.] Higgs coupling [ILC] m h/ The h H 3 mixing changes all the SM Higgs couplings by a factor of cos θ 1. Falkowski, Gross, Lebedev, 15; Profumo, Ramsey-Musolf, Wainwright, Winslow, 14 Invisible decay h H 3H 3 (H 3 decaying outside detector) opens when m H3 < m h /2. Peskin, 12; Baer, 13 Rare decay Z γh 3 (H 3 γγ), induced by the SM fermion loops. Jaeckel, Spannowsky, 15 Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

27 Expected LLP LHC sin θ LHC [0.6] LHC [1.0] LHC [1.5] MATHUSLA [0.6] MATHUSLA [1.0] s = 14 TeV 3000 fb -1 sin θ LHC [0.6] LHC [1.0] LHC [1.5] MATHUSLA [0.6] MATHUSLA [1.0] s = 14 TeV 3000 fb m cm 0.01 cm m cm 0.01 cm Yongchao Zhang (ULB) Light scalar in LRSM Aug 11, / 20

Collider Signatures of the Left-Right Higgs Sector

Collider Signatures of the Left-Right Higgs Sector Bhupal Dev Washington University in St. Louis 5th Workshop on High Energy Physics Phenomenology IISER Bhopal December 8, 207 B L breaking Natural way