Physics Beyond the Standard Model at the LHC

Transcription

1 Physics Beyond the Standard Model at the LHC G G Ross, Edinburgh 7th February 2007 The Standard Model as an Effective Field Theory Beyond the Standard Model The LHC as a probe of BSM physics

2 The Standard model as an effective field theory SU(3)! SU(2)! U(1) : G µ a=1..8, W µ a=1..3, B µ A µ! A µ + " µ #! u$ " # d% &! " # H + H 0 L $ % &, u R, d R,!' $ " # e% & L, e R, ' R (?) f R! e i" R f R!! L SM effective! M A A µ Aµ + m f f L f R + M 2 H H 2 The hierarchy problem : M H not forbidden by SM symmetry: t H H M 2 H! h t # t dk 2 = h2 16! " 2 16! 2 " 2! " 1TeV??

3 Solutions to the hierarchy problem! " 1TeV?? H H Composite: technicolour, walking technicolor, strongly coupled Standard Model, t t Symmetry protection SUSY H t! H Goldstone: little Higgs Double protection H T.. T.. H! fundamental! 1TeV! Xtra dimensions R V (r) = 1 m 1 m 2 2, D = 4 + d, r! R M 2+ M d R d Planck r * = M * 2 ( M * R) d x ( Anthropic ) Split SUSY.

4 These ideas will be tested at the LHC:! New physics " 1TeV Composite: technicolour, walking technicolor New strong interaction, technifermions, composite structure to H, q, W Symmetry protection SUSY SUSY states Spectrum determined by soft SUSY breaking many possibilities Bulk Gaugino SUGRA gauge Anomaly

5 These ideas will be tested at the LHC: Composite: technicolour, walking technicolor New strong interaction, technifermions, composite structure to W s Symmetry protection SUSY Little hierarchy problem! = a "M Z M Z "a # 20 MSSM! New physics " 1TeV Goldstone protection: little Higgs New heavy T.. Quarks, New gauge bosons Double protection - SUSY + Goldstone SU(3)! SU(2) L! SU(2) R! Z 2 +T, B,! H, N! = O(1)!m 2 H = " 3 8# y 2 2 t m 2 2 ( t! + m T )ln m t! 2 2 ( + m T ) " m!2 t ln(m!2 t ) " m 2 T ln(m 2 T )

6 These ideas will be tested at the LHC:! New physics " 1TeV Composite: technicolour, walking technicolor New strong interaction, technifermions, composite structure to W s Symmetry protection SUSY SUSY states Goldstone: little Higgs New heavy T.. Quarks, New gauge bosons Double protection - SUSY + Goldstone Xtra dimensions Kaluza Klein excitations String excitations

7 Kaluza Klein states e.g. 1 extra dimension compactified on a circle!(x, y) = & 2! = 0 KK tower $ % n=#$ " n (x)e iny / R massless mode in 5D $ ' (& 2 x + & 2 y )!(x, y) = (& 2 x " n (x) # n * % ( ) R+, " n (x))e iny / R = 0 n=#$ m! 1 R =! M * # " TeV #! 2 x " n (x) = m 2 " n (x), m 2 = n & $ % R' ( $ & % n n'31 n ev 2 x 0 y/r 2 y = 10!3 ev, 20keV, 7 MeV, 100MeV ; n = 2, 4, 6, 8 R R 4! S 1!

8 String Structure : 1 st string revolution Type I Ghost free condition : Type IIA SO(32) D=10 Fermionic (+SUSY) Type IIB E8 2 String excitations : m string = J! ' + C J Compactification m2 D=10 D=4 +(D=6) compactified radius R Kaluza Klein & winding modes m = n R + p R! ' Gauge structure : restricted by anomaly cancellation Green Schwarz e.g. E 8! E 8 (D = 10) " E 8! E 6 (D = 4)! (N = 1 SUSY ) E 6! SO(10), SU (5)! SU (3) " SU (2) "U (1) +chiral structure for q, l ; multiplet structure determined by Calabi Yau 3 generation examples known Supersymmetry

9 These ideas will be tested at the LHC: Composite: technicolour, walking technicolor New strong interaction, technifermions, composite structure to W s Symmetry protection SUSY SUSY states! New physics " 1TeV Goldstone: little Higgs New heavy T.. Quarks, New gauge bosons Double protection - SUSY + Goldstone Xtra dimensions Kaluza Klein excitations String excitations ( Anthropic ) Split SUSY. Gluino stable on detector timescales SUSY without the LHP

10 My preference : weak-scale SUSY - stabilises the EW scale: m F m B < O(1 TeV) - predicts a light Higgs m h < 130 GeV - accomodates heavy top quark SU(3)! SU(2)! U(1) " SU(3)! U(1) Erler hep-ph/ Ellis, Heinemeyer, Olive, Weiglein CMSSM hep-ph/ predicts gauge unification - dark matter candidate: neutralino, sneutrino, gravitino,... WMAP constrains models, e.g. but relaxing models, opens up the parameter space - consistent with EW data

11 SUSY at the LHC M sp (GeV)! (pb) Evts/yr fb -1 Cascade decays Main signal: lots of activity (jets, leptons, taus, missing E T ) de Roeck Needs good understanding of detector and SM processes

12 Global Fits χ 1 to Present Data χ ±,χ 1 stau 1 Preferred sparticle masses for tan β = 10 stop 1 gluino Ellis + Heinemeyer + Olive + Weiglein:

13 SUSY Higgs 5 Higgs h, H, A, H ±, A CP odd

14 Split SUSY Arkani-Hamed, Dimopoulos Romanino, Giudice The gluino is stable on detector time-scales It hadronizes in R-hadrons (-mesons, -baryons, - gluons) If charged: slow, highly ionizing track If neutral: missing energy, mild hadronic activity, triggered by single jet (gluon emission) Energy, charge, Baryon-number exchange Sensitivities: Run II: ~200 GeV; LHC: 1 TeV (model independent) Run II: ~400 GeV; LHC: 2.5 TeV (if charged) [Baer Cheung Gunion, Raby Tobe, Mafi Raby; recent studies: Kraan, Kilian Plehn Richardson Schmidt, Hewett Lillie Masip Rizzo] Also: gluinium [Cheung, Keung]; gluinos from cosmic rays (if seen give a lower limit on the SUSYbreaking scale) [Hewett Lillie Masip Rizzo, Anchordoqui Goldberg Nunez]

15 Xtra dimensions at the LHC

16 Xtra dimensions at the LHC example Graviton production Graviton escapes detection escape! About 25% increase in reach

17 KK production - universal extra dimensions Everybody in the bulk! e.g. Cheng, Matchev, Schmaltz hep-ph/ Search: e.g 4 leptons + E T miss Spectrum very similar to SUSY spectrum with near degeneracy

18 Xtra dimensions at the LHC Kaluza Klein production q, l, W,... Characteristic signal KK tower builds up Xtra dimension TeV Strings String model M S =410 GeV String Regge contribution may dominate over KK contribution Bhabha KK exchange M H =830 GEV Cullen, Perelstein, Peskin Cullen, Perelstein, Peskin

19 Black Holes 10 events/ per year Landsberg,Dimopoulos

20 Extreme cases: No Higgs! Chanowitz, Gaillard Perturbative unitarity violation: Expect strong V L V L scattering (resonant or non-resonant) at TeV scale q q V L V L q q V L V L

21 Extreme cases: Double protection: M SUSY! 10TeV M T, M WR! 1TeV Berezhiani, Chanowski, Falkowsky,Pokorski, Schmaltz

22 Summary LHC probes natural scale for BSM physics:!! SHUTDOWN F. Moortgat, A. De Roeck /E T... missing signals generic...will need careful work to distinguish possibilities