the 16th international conference on supersymmetry and the unification of fundamental interactions
DESCRIPTION
The 16th International Conference on Supersymmetry and the Unification of Fundamental Interactions June 16 - 21, 2008 Seoul, Korea. String Physics at the LHC. ATLAS. ALICE. CMS. Luis Anchordoqui. Outline. ✻ String theory and all that. ✻ Extra U (1)´s in D-brane constructions. - PowerPoint PPT PresentationTRANSCRIPT
The 16th International Conference on Supersymmetryand the Unification of Fundamental Interactions
June 16 - 21, 2008Seoul, Korea
ATLASATLAS
ALICEALICE
CMSCMS
Luis Luis AnchordoquiAnchordoqui
String Physics at the LHCString Physics at the LHC
Outline Outline
✻ ✻ String theory and all String theory and all thatthat✻ ✻ Extra Extra UU (1)´s in D-brane (1)´s in D-brane constructionsconstructions✻ ✻ Photons and gluons as quiver Photons and gluons as quiver neighborsneighbors✻ ✻ LHC discovery reachLHC discovery reach
➣➣Works done in colaboration withWorks done in colaboration with
Haim Goldberg, Satoshi Nawata and Tom TaylorHaim Goldberg, Satoshi Nawata and Tom Taylor
PRL100, 171603 (2008) arXiv:0712.0386; arXiv:0804.2013PRL100, 171603 (2008) arXiv:0712.0386; arXiv:0804.2013
TeV Scale StringsTeV Scale Strings
➣ ➣ Large extra spatial dimensions and D-brane Large extra spatial dimensions and D-brane constructs allowconstructs allow low string scale compatible with weak 4-D gravity low string scale compatible with weak 4-D gravity
Regge recurrences in TeV regionRegge recurrences in TeV region
➣➣Open strings can terminate on stack of N identical D Open strings can terminate on stack of N identical D branesbranes U(N) gauge group for each stack U(N) gauge group for each stack
Polchinski PRL75, 4724 (1995)Polchinski PRL75, 4724 (1995)
Antoniadis, Arkani-Hamed, Dimopoulos and Dvali PLB436, 257 (1998) Antoniadis, Arkani-Hamed, Dimopoulos and Dvali PLB436, 257 (1998)
Gauge FieldsGauge Fields
■ ■ U(3)U(3) : 8 SU(3) gluons, : 8 SU(3) gluons, additional U(1) additional U(1) →→ C C μμ
coupled to baryon numbercoupled to baryon number
■ ■ U(2)U(2) : 3 SU(2) W´s, : 3 SU(2) W´s, additional U(1) additional U(1) →→ XXμμ
■ ■ U(1)U(1) : another extra U(1) : another extra U(1) →→ BBμμ
Y Y (hypercharge) =(hypercharge) = linear comb of linear comb of C , X , B C , X , B μμμμ μμ μμ
ConverselyConversely
Antoniadis, Kiritsis and Tomaras PLB486, 186 (2000)Antoniadis, Kiritsis and Tomaras PLB486, 186 (2000)
■■ MinimalMinimal Sp(1) : 3 W´s,Sp(1) : 3 W´s, no additional U(1)no additional U(1)Berenstein and Pinansky PRD75, 095009 (2007)Berenstein and Pinansky PRD75, 095009 (2007)
Minimal Quiver Standard ModelMinimal Quiver Standard Model
Berenstein and Pinansky PRD75, 095009 (2007) Berenstein and Pinansky PRD75, 095009 (2007)
gg gg → → gg
■■ Does not exist at tree level in field theoryDoes not exist at tree level in field theory
■■ But does exist at ¨tree¨ (i.e. disk) level in string But does exist at ¨tree¨ (i.e. disk) level in string theorytheory ■■ Involves only gauge bosons Involves only gauge bosons
so is so is independent of the fermion embeddingsindependent of the fermion embeddings
■■ Idea is thatIdea is that
Amplitudes Amplitudes
The basic string partial amplitude is The basic string partial amplitude is
((MHV, or Maximum Helicity Violating)MHV, or Maximum Helicity Violating)
Veneziano form factorVeneziano form factor
Parke and Taylor PRL56, 2459 (1986)Parke and Taylor PRL56, 2459 (1986)Stieberger and Taylor PRL97, 211601 (2006)Stieberger and Taylor PRL97, 211601 (2006)
Squared AverageSquared Average
Now Now permute, permute, square,square, sum,sum, averageaverage andand projectproject onto onto photon:photon:
●●
●●
●●
Limiting CasesLimiting Cases
At low energiesAt low energies s, t, u s, t, u « M²« M²ss
❖ ❖ Note that (unwanted) zero mass poles have cancelled –Note that (unwanted) zero mass poles have cancelled – not trivial!not trivial! Usually implemented by hand through choice of Usually implemented by hand through choice of Chan- Paton factorChan- Paton factor ❖❖
Near string threshold s Near string threshold s ≈ ≈ MM²²ss
Burikham, Figy and Han PRD71, 016005 (2005) Burikham, Figy and Han PRD71, 016005 (2005) Cheung and Liu PRD72, 015010 (2005) Cheung and Liu PRD72, 015010 (2005) Meade and Randall JHEP0805, Meade and Randall JHEP0805, 003 (2008) See, 003 (2008) See, however, Cullen, Perelstein and Peskin PRD62, 055012 (2000)however, Cullen, Perelstein and Peskin PRD62, 055012 (2000)
Scattering proceeds through J = 0 and J = 2 angular momentaScattering proceeds through J = 0 and J = 2 angular momenta
Phenomenology Phenomenology
■ ■ At collider At collider
resonance formation and decay will populate high resonance formation and decay will populate high kk
region region
■ ■ SM processes for SM processes for pppp → → + jet+ jet
TT
Lead to rapid Lead to rapid ~ ~ kk fallofffalloff
■ ■ Take as our signal N above SM background Take as our signal N above SM background
for integrated cross section for integrated cross section
TT --55
eevv
vs.vs. kkTT,mi,minn
σσ vs.vs. M M ss
Major experimental background Major experimental background
misidentification with high misidentification with high k k ππºº- - O O (10(10³) ³)
multipliermultiplier
Gupta, Choudhary, Chatterji, Bhattacharya and Shivpuri Gupta, Choudhary, Chatterji, Bhattacharya and Shivpuri arXiv:0705.2740arXiv:0705.2740
Isolated prompt Isolated prompt photonsphotons
Imposition of isolation cutsImposition of isolation cuts
reduces event rate for the high reduces event rate for the high kk π㧧 background backgroundTT
TT
ββ
IntroducingIntroducing
Increases effective background by factor Increases effective background by factor →→
Decreases S/N ratio byDecreases S/N ratio by
QCD background from direct photon production ≈ 8.1 QCD background from direct photon production ≈ 8.1 x 10x 10
5
(for 100 fbˉ(for 100 fbˉ¹)¹)
Bump-huntingBump-hunting ■ ■ Hope to see resonance bumps in data binned inHope to see resonance bumps in data binned in
M =M = invariant mass of invariant mass of + jet+ jet
TT
■ ■ Integrate over Integrate over [M - 2[M - 2M + 2M + 2]] find S/N find S/Nssss
■ ■ Impose rapidity (Impose rapidity (yy) and ) and kk cuts on photon and jet cuts on photon and jet and measure cumulative cross sections and measure cumulative cross sections
■ ■ Look for regions with significant deviations from Look for regions with significant deviations from QCD background, QCD background, find interval with bump!find interval with bump!
Signal-to-NoiseSignal-to-Noise
Discovery ReachDiscovery Reach
ALICE ALICE
■■ We may simultaneously compare the colliding We may simultaneously compare the colliding
PbPb facility with the proton beam for our searchPbPb facility with the proton beam for our search
■■ Flux greater by factor of A Flux greater by factor of A
energy/parton less by factor of Z/A ≃energy/parton less by factor of Z/A ≃ 0.30.3
■■ Ignore parton shadowing, assumeIgnore parton shadowing, assume
ALICE ALICE
Sensitivity requires pbˉSensitivity requires pbˉ¹¹ → → above present day estimate of integrated above present day estimate of integrated luminosityluminosity
Remarks and Remarks and ConclusionsConclusions✻✻ We have identified a tree-level process unique to We have identified a tree-level process unique to
strings, independent of embeddingstrings, independent of embedding
✻✻ Discovery of TeV-scale string physics (at 5Discovery of TeV-scale string physics (at 5) )
possible for M ~ 2.3TeV with 10% C-Y mixingpossible for M ~ 2.3TeV with 10% C-Y mixingss
✻✻ Results are conservative in thatResults are conservative in that
● ● string corrections to SM processes not includedstring corrections to SM processes not included
●● contribution from tails of higher resonances not contribution from tails of higher resonances not includedincluded✻✻ High-High-kk Z production suppressed relative to Z production suppressed relative to ’s ’s
by a factor of tanby a factor of tan²²θθ = 0.3 = 0.3 differs radically differs radically
from evaporation of black holes produced at the from evaporation of black holes produced at the
LHCLHC
WW
TT