1 / 15

Main Issues in ADD phenomenology

Main Issues in ADD phenomenology. Find out of there are signals for Kaluza-Klein towers of gravitons ─ large-p T excess, missing energy, etc.

Download Presentation

Main Issues in ADD phenomenology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Main Issues in ADD phenomenology • Find out of there are signals for Kaluza-Klein towers of gravitons ─ large-pT excess, missing energy, etc. • Determine whether the signals are indeed due to brane-world gravitons and not some other new physics ─ gravitons would be blind to all SM quantum numbers • Identify these particles as graviton modes ─ spin-2 nature is a dead giveaway • Find out the number of large extra dimensions • Find out the radius of compactification Rc, or equivalently, the bulk Planck scale (string scale Ms) • Find out the geometry of the extra dimensions • Find out dynamics which makes some dimensions large & some small LHC LHC LHC

  2. ADD phenomenology at e+ e- colliders: Virtual process Excess in pair-production of SM particles Variation in angular distribution of final states Real process Radiation off a SM particle Missing energy from radiated graviton

  3. Real Gravitons: each ADD graviton couples as (MP)-1 • escapes detection missingE, psignals • Most important process for real gravitons is • e+ e- * G • Single-photon + missing energy signals (Peskin et al) • Worked out in LEP context: extended to LC e+ Gn 2 Sn * Incoherent sum e- 

  4. Need to distinguish from all sorts of other new physics • e.g. extra neutrinos, neutralinos, gravitinos, etc. • Focus on angular distribution of single photon • Gopalakrishna, Perelstein, Wells (Snowmass, hep-ph/0101339) • Confirmatory process I: e+e-  m+m- G • Eboli, Magro, Mathews, Mercadante (PRD. hep-ph/0103053) • 2  3 process; 14 Feynman diagrams • Confirmatory process II: e+e-  e+e- G • S.Dutta, P.Konar, B.Mukhopadhyaya, SR (PRD, hep-ph/0307117) • 2 3 process; 28 Feynman diagrams (add t-channel) • Predict significant deviations from Standard Model • Total cross-section Kinematic distributions • Results of single photon process and this one will be correlated • Can determine the number of extra dimensions

  5. Dutta, Konar, Mukhopadhyaya, SR

  6. Virtual gravitons can produce any pair of SM particles: e+ e- , m+m- , t+t- , q q , g g , g g , Z Z , W+ W- • Giudice, Rattazzi, Wells (1998), Han, Lykken, Zhang (1998) • Hewett & Rizzo (1998 – 2003), Kingman Cheung (1998, 2001) • Agashe, Deshpande (1999) e+ 2 Sn Coherent sum Gn e- At low energies MS»slooks like a contact interaction

  7. Q. How to distinguish these from other kinds of new physics? • Spin-2 nature of graviton is the giveaway How to utilise this best? 1. K.Y.Lee, H.S.Song, J.H.Song, C.Yu (1999)spin correlations of top quarks 2.Poulose (2001)forward-backward asymmetry e+ e- W+ W- 3.Rizzo (2002)multipole moments of e+ e- m+m-cross-section etc. 4. Osland, Pankov, Paver (2003)different asymmetries Critical study required!

  8. RS Metric: Free parameters: Masses of gravitons m0 ~ 100 GeV (electroweak scale) Coupling of gravitons ~ c0= K / MP ~ few %

  9. Main Issues in RS phenomenology • Find out of there are signals for graviton resonances ─ bump hunting… • Determine whether the resonances are indeed RS gravitons and not some other new physics ─ RS graviton masses are spaced like zeros of Bessel function J1 • Identify these resonances as graviton modes ─ spin-2 nature is a dead giveaway • Find out if there are signals for radions─ very similar to Higgs search • Find out the mass and coupling parameters ─ mass and width measurements (like W,Z at Tevatron) • If the resonances are broad distinguish between RS and ADD models • Distinguish the radion from a Higgs scalar LHC LHC LHC LHC

  10. RS graviton phenomenology: • RS graviton width grows rapidly with graviton mass • Only first three modes can form narrow resonances • For large part of parameter space only first resonance is viable • RS gravitons decay to all particle pairs • Maximum BR is to jets; sizeable width to WW and ZZ • No deviations from SM at LEP-2  lightest RS graviton is heavier than210 GeV • Tevatron Drell-Yan data show no deviations either  lightest RS graviton is heavier than ~ 480 GeV • LC: smaller s but clean final states: • graviton resonances in Bhabha scattering ande+e- +-

  11. Graviton resonances in e+e- +- Hewett & Rizzo (2002) K /MP varies between 0.01 and 0.1

  12. Final states will have angular distributions carrying signatures of spin-2 nature of RS gravitons • E.g. e+e- +- (e.g.LHC:Allanach, Odagiri, Parker, Webber, JHEP) • Vector exchange:s  1 + cos2 q peaks along beam pipe • Tensor exchange:s  1 - 3cos2 q + 4cos4 qalso transverse peak • Complementary process: Single photon signals for RS gravitons • S.K.Rai and SR (JHEP, hep-ph/0307096) • Process is e+e-  • Single photon recoils against massive graviton modes • Photon spectrum shows peaks corresponding to graviton masses • For largeK /MP resonances broaden into continuous spectrum — difficult to distinguish between ADD/RS • Can distinguish between ADD and RS by comparing e+e- m+m- • Both 2  2 in ADD, single photon is 2  3 in RS

  13. Photon Energy Distribution would show multiple resonances

  14. Correlation plot between e+e- E and e+e-+- SM Rai and SR

  15. What is to be done? • Prepare consolidated list of formulae for all cross- sections, both for real and virtual gravitons. Use the same parameterizations, same set of conventions • Keep helicity states of e+ e- to take care of beam polarization • Incorporate in an event generator which is standard, user-friendly, flexible • Include ISR and beamstrahlung effects • Construct asymmetries, multipole moments etc. • Detector simulation

More Related