Other BSM Searches at LHC Dimitri Bourilkov University
Other BSM Searches at LHC Dimitri Bourilkov University of Florida for the ATLAS and CMS Collaborations 19 th Hadron. Collider. Physics Symposium HCP 2008, May 2008, Galena, IL, USA
W’ Z’ And the wi nner is … Place your bets! HSCP ADD Y RS SUS LQ Λ+- ρT g* BH D. Bourilkov Other BSM Searches at LHC HCP 2008 2
Introduction • • • A vast search field; I’ll only have time to cover selected topics(disclaimer: any omissions are accidental) The searches are organized by experimental signatures, not by models Focus is on “clean”, low background channels which can provide early discoveries (once the machine, detectors and Standard Model contributions are understood well enough) Most results are for 14 Te. V, but ~ 40 pb-1 at 10 Te. V have interesting potential We better be ready from the start: W/Z were discovered by UA 1/UA 2 with ~20/55 -1 nb {but they knew where to look} D. Bourilkov Other BSM Searches at LHC HCP 2008 3
1 Lepton + Missing E T ATLAS • Additional gauge boson W’ (SSM) • W’ μνμ • Standard Model backgrounds: > W μνμ > Z μμ > • Di-jet QCD Clear signature: hard lepton + missing energy can lead to fast discovery D. Bourilkov Other BSM Searches at LHC HCP 2008 4
1 Lepton + Missing E T CMS • Additional gauge boson W’ (SSM) • W’ μνμ • Standard Model backgrounds: the usual suspects > W μνμ > Z μμ • > Di-jet QCD > tt > WW, ZZ Clear signature: hard lepton + missing energy can lead to fast discovery D. Bourilkov Other BSM Searches at LHC HCP 2008 5
LHC as Bump Hunting Factory Simple final states without missing energy; can reconstruct invariant mass Cumulative plots Early discovery ? > “Easy” – resonances > “Not-so-easy” –nonresonant. OR just a resonance tail LHC is a di-{lepton, photon, jet} factory Test Standard Model to highest momentum transfers Signals for many new physics scenarios: compositeness, Z’, extra dimensions: Randall. Sundrum(RS) gravitons, ADD … D. Bourilkov Other BSM Searches at LHC HCP 2008 6
Drell-Yan Event Rates @ 10 Te. V Rough estimate: no K-functions, no efficiency ee(OR μμ) Mass [Ge. V] TOTAL [pb] Acceptance | 1, 2|<2. 4 SEL [pb] 40 -70 117. 2 0. 357 41. 9 70 -120 1129 0. 478 Events 1 pb-1 100 pb-1 42 4200 540 54000 7 70 700 0. 5 5 50 120+ 13. 2 0. 515 6. 8 250+ 0. 78 0. 628 0. 49 500+ 0. 058 0. 741 0. 043 - 0. 4 1000+ 0. 0029 0. 806 0. 0024 - - 0. 2 2000+ 0. 00006 0. 823 0. 00005 - - - 4 The errors from PDF uncertainties are 4 -8 % for the 500+ or 1000+ bins. Fo 10 pb-1 the DY background to new physics is negligible above 500 Ge. V, for 100 pb-1 above 1 Te. V. Any statistically significant accumulation of events i these areas would signal new physics. D. Bourilkov Other BSM Searches at LHC HCP 2008 7
2 Leptons CMS • Bump hunting • Additional gauge boson Z’ (many scenarios) • Z’ ll (ee or μμ) • Standard Model backgrounds: > */Z ll (Drell-Yan) > Di-jet QCD Z’SSM 100 pb-1 Z’ψ 100 pb-1 > W + jets > tt > WW, ZZ D. Bourilkov Other BSM Searches at LHC HCP 2008 8
2 Leptons CMS • Z’ μμ • Effects of misalignment studied • Clear signature: 2 hard leptons + invariant mass peak can lead to fast discovery(2008 Update, full simulation) • LEP 2 SSM limit: M Z’ > 1. 8 Te. V Z’ψ Z’SSM RS 1 graviton c = 0. 01, 0. 02, 0. 05, 0. 1 D. Bourilkov Other BSM Searches at LHC HCP 2008 9
2 Leptons CMS • Z’ ee • Spin discrimination • Saturation correction: above 1. 7 Te. V barrel, 3 Te. V endcaps; mass resolution barrel 0. 6 % (7%) without (with) saturation • Physics TDR Graviton (blue); Drell-Yan(red) Z’ (LR) (red) D. Bourilkov Other BSM Searches at LHC HCP 2008 10
2 Leptons ATLAS • Studied the CDDTparametrizationfor Z’ ee • 3 parameters: > MZ’ mass of the additional gauge boson > g. Z’ global coupling strength > x • relative coupling strength to different fermions 4 classes of solutions: Bx. L, 10+x 5, d-xu, q+xu D. Bourilkov Other BSM Searches at LHC HCP 2008 11
2 Leptons ATLAS CDDT parametrizationfor Z’ ee D. Bourilkov Other BSM Searches at LHC HCP 2008 12
2 Photons CMS Photon energy corrections as for electrons 5 discovery reach for RS gravitons D. Bourilkov Other BSM Searches at LHC HCP 2008 13
2 Jets CMS dijet mass from QCD and resonances; early observations are possible D. Bourilkov Other BSM Searches at LHC HCP 2008 14
3 Leptons ATLAS CMS • “Walking” gauge coupling lowers the scale oftechnicolormodels • Light almost degenerate vector technimesons • Decay ρT/a. T WZ 3 l D. Bourilkov Other BSM Searches at LHC HCP 2008 15
2 Leptons + 2 Jets ATLAS • Leptoquarkscarry both lepton and baryon numbers • Assumptions: Couple to only one generation quarks and leptons of Interactions arechiral • Pair production • Decay LQ q + μ • Main backgrounds: Drell-Yan, tt, ZZ, ZW, WW • Current limits ~ 250 -540 Ge. V depending on LQ type (LEP 2, Tevatron) D. Bourilkov Other BSM Searches at LHC HCP 2008 16
Top-Top Resonance ATLAS • Resonance decaying to top-antitop(one W to hadrons, 2 nd to e or μ+ν) • E. g. in Te. V-1 extra dimension models: Kaluza-Klein excitation of gluon • Sensitivity will reach 3. 3 Te. V D. Bourilkov Other BSM Searches at LHC 3 fb-1 HCP 2008 17
HERA Contact Interactions LEP LHC general framework for new interactions: • scale s (virtual effects)or resonances if s • 2 = 4 ) couplingg (convention g • we constraing / • operators with canonical dimension N > 4 terms ~ 1/ N-4 D. Bourilkov Other BSM Searches at LHC HCP 2008 18
PDF Uncertainties Before we claim discoveries – make sure we understand. Parton the Density Functions • • LHAPDF library / LHAGLUE interface - now version 5. 3. 1 - to MC generators PYTHIA and HERWIG available -THE “ LES HOUCHES ACCORD PDFS (LHAPDF) AND LHAGLUE”, hep-ph/0508110 Collaboration. M. Whaley, D. Bourilkov, C. Group -“LHAPDF: PDF USE FROM THE TEVATRON TO THE LHC”, hep-ph/0605240 re-weighting technique tested D. Bourilkov Other BSM Searches at LHC HCP 2008 19
Double Ratio Method for Dileptons CMS • • Double ratio method for dileptons: use e. g. mass bin 250 -500 Ge. V for normalization (SM valid; Tevatron); prefer to use data above the Z due to the flavor composition / PDF For higher masses (bins 1 – n): Ri. DATA = Ni. D/N 0 D = i. D / 0 D. 0 D Ri. MC = Ni. MC/N 0 MC = i. MC / 0 MC • • • Many things cancel in the ratios: luminosity, absolute efficiency, Kfactor etc. ; absolute values are not important, only the shapesas function of mass If theory understanding and detector modeling are both perfect DRi = 1 LEP 2 limits: Λ >~ 8 Te. V D. Bourilkov Other BSM Searches at LHC HCP 2008 20
Contact Interactions with Dijets CMS 2008 update: use inclusivejep PT (left) or dijet ratio N(| | < 0. 7) /N(0. 7 < | | < 1. 3) as function ofdijet mass LEP 2 limits: Λ >~ 8 Te. V D. Bourilkov Other BSM Searches at LHC HCP 2008 21
Heavy Stable Charged Particles CMS • • HSCP can be slow (v < c) but hard (p >~ 100 Ge. V) can measure mass ifβ and p are measured Can measureβ two times: in themuon stations Drift tubes (time-of-flight TOF) and the tracker (specific ionization d. E/dx) D. Bourilkov Other BSM Searches at LHC HCP 2008 22
Black Holes ATLAS CMS • Mini blackholescan be copiously produced in extra dimension models with low Planck scale • Striking signatures: flavor democratic Hawking radiation high multiplicity “circular” events • Can be observed very fast ATLAS CMS – mass andsphericityplots D. Bourilkov Other BSM Searches at LHC HCP 2008 23
Outlook • • ATLAS and CMS are about to start exploring the Te. V scale Rich search field for early discoveries at the multi. Te. V scale: resonances first; fix scale for new physics? Be ready for first data: detector, data acquisition, software; avoid “discovering” detector features Many other searches: single photons, heavy Majorana neutrinos and right-handed bosons, little Higgs, doublycharged scalars, isosingletquarks, same sign top, WW scattering … We are embarking on a journey: expect the unexpected! D. Bourilkov Other BSM Searches at LHC HCP 2008 24
Backup Slides D. Bourilkov Other BSM Searches at LHC HCP 2008 25
The Detectors ATLAS Magnet Solenoid: 2 T CMS Solenoid: 4 T Air-coretoroids: 0. 5 T Tracker /PT(Ge. V) Si Pixel & Strips, TRT -4 (d 0) [μm] 4 x 10 PT 0. 001 15 @ 20 Ge. V ECAL LAr /E(Ge. V) 10%/√E 0. 7% HCAL D. Bourilkov /P T 1. 5 x 10 -4 PT 0. 005 Pb. W 04 crystals 3%/√E 0. 5% Steel-scintillatortile Brass-scintillator /E(Ge. V) 50%/√E 3% Muon Si Pixel & Strips DT/CSC/RPC/TGC 100%/√E 5% DT/CSC/RPC BSM Searches at LHC 10%Other @1 Te. V 5% HCP 2008 @ 1 Te. V(with tracker)26
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