Strings, Exotics, and the 750 GeV Diphoton Excess

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1 Strings, Exotics, and the 750 GeV Diphoton Excess Events / 0 GeV 4 ATLAS Preliminary Data Background-only fit Spin-0 Selection s = 1 TeV,. fb The ATLAS and CMS results 1 Phenomenology and theory Data - fitted background [GeV] m γγ String consistency, heavy exotics, and the diphoton excess M. Cvetič, J. Halverson, PL, , , 06.41

2 ATLAS and CMS Diphotons at 750 GeV ATLAS and CMS high p T diphoton searches: spin-0 (heavy Higgs), spin- (KK graviton) ATLAS-CONF , (.fb 1 at 1 TeV; 0 fb 1 at 8 TeV) CMS PAS EXO6-018, (.fb 1 at 1 TeV fb 1 at 8 TeV) Events / 0 GeV 4 1 ATLAS Preliminary Data Background-only fit Spin-0 Selection s = 1 TeV,. fb Events / ( 0 GeV ) CMS Preliminary EBEB.7 fb (1 TeV,.8T) Data Fit model ± 1 σ ± σ 1 1 Data - fitted background m γγ [GeV] (data-fit)/σ stat (GeV) m γ γ

3 95% C.L. limit σ(pp S γγ) (fb) CMS Preliminary fb (1 TeV) fb (8 TeV) -4 m Γ = 1.4 J=0 Expected limit ± 1 σ ± σ Observed limit 95% C.L. limit σ(pp S γγ) (fb) CMS Preliminary. fb (1 TeV) fb (8 TeV) 1 m Γ = 1.4 J=0 Expected limit ± 1 σ ± σ - Observed limit 95% C.L. limit σ(pp S γγ) (fb) CMS Preliminary. fb (1 TeV) fb (8 TeV) - m Γ = 5.6 J=0 Expected limit ± 1 σ ± σ Observed limit 0 5 m S (GeV) 0 5 m S (GeV) 0 5 m S (GeV) BR [fb] 95% CL Upper Limit on σ fid Observed CL s limit Expected CL s limit Expected ± 1 σ Expected ± σ ATLAS Preliminary s = 1 TeV,. fb = 1 % Γ X /m X Spin-0 Selection BR [fb] 95% CL Upper Limit on σ fid Observed CL s limit Expected CL s limit Expected ± 1 σ Expected ± σ ATLAS Preliminary s = 1 TeV,. fb = % Γ X /m X Spin-0 Selection BR [fb] 95% CL Upper Limit on σ fid Observed CL s limit Expected CL s limit Expected ± 1 σ Expected ± σ ATLAS Preliminary s = 1 TeV,. fb = 6 % Γ X /m X Spin-0 Selection [GeV] m X [GeV] m X [GeV] m X CMS: (small) NWA preference ATLAS: (small) broad Γ/M 6% preference

4 CMS: 8+1 TeV.4σ (local), 1.6σ (global) ATLAS: 1 TeV.9σ (local),.0σ (global) σb γγ 1 fb (will take 8 fb) σ(1)/σ(8) 4.7 for GG fusion,.7 for q q GG: CMS, ATLAS both compatible, used in CMS analysis q q less compatible (1.9 [γγ]; 5.4 [b b]; small PDFs) No reported signal for dijet, l + l, b b, t t, HH, W W, ZZ, Zγ Spin- similar (disfavored by f f, etc) (spin excluded by Landau-Yang) - log L CMS Preliminary 6 5. fb (1 TeV) fb (8 TeV) - log L CMS Preliminary 6 5. fb (1 TeV) fb (8 TeV) 4 m=750 GeV, J=0 - = m Γ Combined 8TeV 1TeV 4 m=750 GeV, J= - = m Γ Combined 8TeV 1TeV σ 1TeV B (fb) γ γ σ 1TeV B (fb) γ γ

5 Phenomenology and Theory N signal N theory Topologies A. Strumia, Moriond 016 Decaying spin-0 (S) Scalar (s), pseudoscalar (p) or mixed (if CP violation) SUSY: s, p close in mass or well-separated (SUSY mediation) String axion (low string scale); strong dynamics (e.g., heavy axion) Weak coupling (heavy Higgs, remnant, tadpole consistency)

6 Rate σ pp S B γγ C GG Γ GG Γ γγ Γ (for GG fusion) NWA: rate C GG Γ γγ for Γ Γ GG + Γ γγ and Γ γγ Γ GG Large width: need additional decay channels (invisible?, DM?) and larger Γ γγ Γγγ/ Λ / Γ/ Γ Γ γγ σ /σ = σ /σ = Γ / Λγ/ Γγγ/ L =g s ( + e ( σ /σ = σ /σ = Λ / s G µνg µν + p G µν Λ G Γ/ Λ G Γ Γ γγ Γ / G µν s F µνf µν + p F µν Λ γ Λ γ Λγ/ ) F µν ) Franceschini et al,

7 Simplest possibility: weakly coupled S (s or p); loop-induced couplings G G GG fusion favored by σ(1)/σ(8), overall rate SU() singlet favored (rate; s H mixing) S SM particles in loop insufficient (e.g., direct S t t too large) Quasi-chiral exotics (vectorlike wrt SM) in loops (+ possible scalars) (Γ γγ /M: coupling to SM small) New sector orthogonal to naturalness-motivated BSM Typeset by FoilTEX

8 Explicit spin-0 models (partial list) HDM, NMSSM, SUSY, R p, sgoldstini, gluinonia Dark matter, dark portal, hidden valley U(1), SU() L SU() R U(1), enhanced color Axion, dilaton, flavon, time-varying field Quirks Strong coupling, top color, technicolor, composite pion, composite vector Radion Radiative ν W ball 4 th family Grand unification, E 6, Pati-Salam, flipped Strings, axions, low scale, strong coupling F sector, remnants (tadpole consistency)

9 L = γ i sx i X i + iγ 5i px i γ 5 X i Scalar (s): Γ(s GG) = M α π Γ(s γγ) = M α 16π γ i T (i) τ i S(τ i ) i γ i n i i Q τi S(τ i ) i S(τ ) = 1 + (1 τ )P (τ ), P (τ ) = arctan (1/ τ 1) τ i = 4M i /M ; Q i = charge; T (i) = Dynkin index (, 1/, 0) for color dimension n i = (8,, 1) Can also have scalar loops; coupling A terms Pseudoscalar (p): γ i γ 5i, S(τ i ) P (τ i ), no scalar loops

10 Pseudoscalar (τ P(τ) ) Scalar (τ S(τ) ) Limits on Q + Q, L + L extremely model dependent (take M Q > 750, M L > 00) M i Many papers w. various assumptions Can reproduce NWA Large width: only strong coupling at TeV scale or large number of exotics ( strong coupling) Can fake large width by near degenerate s and p ( HDM?; SUSY? Mediation mechanism?)

11 String Remnants Enormous landscape of string vacua Subset consistent with everything we know Often larger than SM or MSSM (string opportunity) String remnants (nonminimal BSM that slips through net ; not motivated by SM problems) Additional TeV-scale U(1) Extended Higgs sector: singlets, multiple doublet pairs Quasi-chiral exotics (vector wrt SM, chiral under new global/gauge symmetries) New dynamics: perturbative global symmetries w. exponentially-suppressed breaking (string instantons)

12 New stringy constraints (SU(), U(1) tadpole constraints; very large groups/representations unlikely) Example: intersecting brane (Type IIA) constructions Assume SM sector perturbative up to large string scale

13 TypesetbyFoilTEX Intersecting Brane (Type IIA) Constructions U(N) from N D6 branes (fill of the 6 extra dimensions) Adjoints, bifundamentals (open); gravitons (closed) Also, symmetric, antisymmetric; SO(N), Sp(N) Families from multiple intersections (-cycles wrapping 6d) Yukawa interactions exp( A ijk ) hierarchies Existing models: additional gauge factors, Higgs, chiral matter Global U(1) s (may be broken by nonperturbative D instantons)

14 Tadpoles and Extended MSSM Quivers Implications of String Constraints for Exotic Matter and Z s Beyond the Standard Model, M. Cvetič, J. Halverson, PL, JHEP 1111,058 ( ); Anomaly Nucleation Constrains SU() Gauge Theories, J. Halverson, PRL 111, (1.91) Intersecting brane type IIA constructions (and others): tadpole cancellation conditions stronger than anomaly cancellation in augmented field theory (for N a = 1, ) (FT with anomalous U(1) s and Chern-Simons terms) U(N a ) from stack of N a D6 branes: N a : #a #a + (N a + 4) (# a # a ) + (N a 4) (# a # a ) = 0 N a = 1 : #a #a + (N a + 4) (# a # a ) = 0 mod, SU(N a ) triangle anomaly condition for N a

15 Landscape view: all vacua must be consistent Additional constraints from existence of hypercharge Most quivers with just MSSM chiral matter don t satisfy tadpole (plus H L) constraints (none for nodes with no vector pairs) Systematically add matter to MSSM quivers to satisfy tadpole and hypercharge conditions (eight and 4-node hypercharge embeddings) Up to 5 additional fields Don t allow purely vector pairs (typically acquire M s -scale masses) Allow quasi-chiral pairs (vector under MSSM; chiral under anomalous or additional non-anomalous U(1) s) May also exclude fractional charge, heavy chiral states, no H d L distinction

16 SM Rep Total Multiplicity Int. El. 4 th Gen. Removed Shifted 4 th Gen. Also Removed (1, 1) (1, ) (1, ) (1, ) (, 1) (, 1) (1, 1) (1, 1) (, 1) (, 1) (, ) (, ) (1, ) (1, ) (1, ) (1, 1) (1, 1) (, 1) (, 1) (, 1) (1, ) (, ) (, 1) (1, ) (, )

17 89780 quivers; have exotics; have singlets that can couple Typical exotic sets (1, 1) 0 (1, ) 1 (1, ) 1 (1, ) 1 (1, ) 1 (1, ) 1 (1, ) 1 (1, 1) 0 (, 1) 1 (, 1) 1 (, 1) 1 (1, ) 0 (1, 1) 0 (, 1) 1 (1, 1) 1 (1, 1) 1 (1, ) 1 (1, 1) 0 (1, ) 1 (1, 1) 0 (, 1) 1 (, 1) 1 (, 1) 1 (, 1) 1 (1, ) 0 (1, ) 0 (1, 1) 0 (, ) 16 (, ) 1 6 (, 1) (1, 1) 1 (1, 1) 1 (1, 1) 0 (, 1) 1, 1) 0 (1, ) (1, )

18 Most Common Exotic Sets (naive estimate) Representations C γγ Γ γγ /M C GG Γ GG /M (1, ) (1, ) (1, 1) (1, 1) (1, 1) 1 + (1, ) (1, ) (, 1) 1 1/ /.5 4 (, 1) 1 / (, 1) 1 + (1, )1 4/ /.5 4 (, 1) 1 + (1, 1) 1 4/ /.5 4 (, )1 6 5/ (, 1) 4/ /.5 4 (, 1) 1 + (, 1) 5/ Sets with perturbative couplings to singlet pseudoscalar. Conjugate included. α = 1/18, α s = 0.1, γ i = 1, m f = M/ = 75 GeV, C = group factor. Widths reduced by 6.1 for a singlet scalar.

19 More Realistic Estimates Larger exotic quark masses Limits very model dependent: M U,D GeV for mixing induced decays (e.g., D W t, Zb, Hb); LQ decays? M L GeV We assume M L > 00, M U,D > 750 Couplings perturbative up to large scale (e.g., 16 GeV) Landau poles for γ 1; smaller Yukawas (e.g., 0.7) from IR fixed point Optional: MSSM-type gauge unification Require more exotics than considered in ; restrict to same quantum numbers

20 RGE Assume SUSY down to TeV scale for definiteness Common type IIA exotics: N D (, 1) 1/ + (, 1) 1/ pairs, N L (1, ) 1/ + (1, ) 1/ pairs N Q (, ) 1/6 + (, ) 1/6 pairs, N U (, 1) / + (, 1) / pairs N E (1, 1) 1 + (1, 1) 1 pairs Gauge couplings ( β gi dg i /dt with t = ln(µ/µ 0 )) 16π β g = g ( + N Q + N U + N D ) 16π β g = g (1 + N Q + N L ) ( 16π β g1 = g ( NQ N U + N D + N )) L + N E

21 Yukawa couplings ( 4 16π β γq = γ Q [ γ Q + α 4 g + 4 g + ( ) 1 )] g ( 4 16π β γu = γ U [ γ U + α 4 g + ( ) )] g 1 5 ( 4 16π β γd = γ D [ γ D + α 4 g + ( ) 1 )] g 1 5 ( 16π β γl = γ L [ γ L + α 4 4 g + ( ) 1 )] g 1 5 ( )] 16π β γe = γ E [ γ E + α 4, 5 g 1 α = 6N Q γ Q + N U γ U + N D γ D + N L γ L + N E γ E

22 Boundary conditions γ = O(0.1 ) at string scale (MC, Papadimitriou, [hep-th/0008]) String Scale Yukawa Coupling 15 IR fixed point: γ IR almost independent of γ UV take γ = 1 at 8 15 GeV 0. 1 λ α = 0.094, α = 0.0, α 1 = at 750 GeV (SM running) ν γ = g s π j=1 [ 16π ] B(ν j, 1 ν j ) 1 4 exp B(ν j, λ j )B(ν j, 1 ν j λ j ) m ( A j(m) πα )

23 Results α α 1 α α γ γ L γ D t t Example: N D = N L =, consistent w. gauge unification; t = ln(µ/m) 0 at µ string 8 15 GeV

24 Γγγ/ Λ / Γ/ Γ Γ γγ σ /σ = σ /σ = Γ / Λγ/ Γγγ/ Γ GG M Λ / σ /σ = Γ Γ γγ M D σ /σ = Γ/ Λγ/ N D - = N L - = (top), (middle), 1, (bottom) Γ / Franceschini et al,

25 Γγγ /M for ND = and NL = Γγγ /M for ND = and NL = MD (GeV) MD (GeV) ML (GeV) ML (GeV) Can fit NWA data for MD. TeV, ML 75 GeV

26 Future Probes/Implications Statistics, distributions, associated productions Decays to dijet, l + l, b b, t t, HH, W W, ZZ, Zγ Vector exotics, superpartners, s/p s H, Q q, L l mixing Possible implications for dark matter, vacuum stability, EWPT

27 Conclusions Intriguing 750 GeV diphoton excess Data suggests new pseudoscalar coupled to GG and γγ by vectorlike fermion loops (M Q TeV) Somewhat orthogonal to SM and usual BSM (dark sector? string remnants?) Other possibilities: axions, spin-, γγ or q q production, different topologies If narrow: could be perturbative up to large scale If broad: strong TeV-scale dynamics (or two nearby resonances) Many models/implementations Type IIA (intersecting brane) constructions

28 Quasi-chiral exotics usually required by tadpole constraints SM singlets (S) common Specific quantum numbers (e.g., D + D, L + L) most common Large Yukawas at string scale small in IR by fixed points In progress: survey of exotic decays/implications (mixing? leptoquark/diquark?, HDO?)

29 p 0 CMS Preliminary. fb (1 TeV) fb (8 TeV) p 0 CMS Preliminary. fb (1 TeV) fb (8 TeV) 1 σ 1 σ σ σ m Γ = 1.4 J=0 Combined σ - - m Γ = 1.4 J=0 Combined σ 8TeV 8TeV TeV m S (GeV) TeV m S (GeV) 0 p CMS Preliminary. fb (1 TeV) fb (8 TeV) 1 σ σ m Γ = 5.6 J=0 Combined 8TeV 1TeV m S σ (GeV)

30 Γ X /m X [%] ATLAS Preliminary s = 1 TeV,. fb Spin-0 Selection Local significance [σ] m X [GeV] 0

31 Anomalous U(1) from trace generator of U(N) usually acquires Stuckelberg mass near string scale M s Anomalies cancelled by Chern-Simons U(1) global symmetry on (perturbative) superpotential May be broken by non-perturbative D-instantons (exponentially suppressed) Linear combination q x U(1) x may be massless, non-anomalous if q a N a (# a # a + # a # a ) + x a q x N x (#(a, x) #(a, x)) = 0, N a q a #(a) #(a) + 8(# a ) # a ) + x a q x N x (#(a, x) #(a, x)) = 0, N a = 1 Require one linear combination weak hypercharge, Y May be additional massless combinations, broken by Higgs singlet VEVs TeV-scale Z (even for M s = O(M pl ))

32 MSSM hypercharge embeddings (Ibanez, Marchesano, Rabadan; Anastasopoulos, Dijkstra, Kiritsis, Schellekens) Three-node embeddings (U() a U() b U(1) c ) Madrid: U(1) Y = 1 6 U(1) a + 1 U(1) c non-madrid: U(1) Y = 1 U(1) a 1 U(1) b Four-node embeddings (U() a U() b U(1) c U(1) d ) U(1) Y = 1 6 U(1) a + 1 U(1) c + 1 U(1) d U(1) Y = 1 U(1) a 1 U(1) b + 1 U(1) d U(1) Y = 1 6 U(1) a + 1 U(1) c + U(1) d U(1) Y = 1 U(1) a 1 U(1) b U(1) Y = 1 6 U(1) a + 1 U(1) c U(1) Y = 1 U(1) a 1 U(1) b + U(1) d,