1 / 37

Little Higgs Dark M atter & Its Collider Signals

Little Higgs Dark M atter & Its Collider Signals. Shigeki Matsumoto (University of Toyama ). ～ Papers ～. ・ E . Asakawa, M. Asano, K. Fujii, T. Kusano, S. M., R . Sasaki , Y . Takubo, and H. Yamamoto, PRD 79, 2009. ・ S . M, T. Moroi and K. Tobe , PRD 78 , 2008.

havard
Download Presentation

Little Higgs Dark M atter & Its Collider Signals

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. Little Higgs Dark Matter & Its Collider Signals Shigeki Matsumoto (University of Toyama) ～Papers ～ ・ E. Asakawa, M. Asano, K. Fujii, T. Kusano, S. M., R. Sasaki, Y. Takubo, and H. Yamamoto, PRD 79, 2009. ・ S. M, T. Moroi and K. Tobe, PRD 78, 2008. ・ S. M, M. M. Nojiri and D. Nomura, PRD 75, 2007. ・ M. Asano, S. M., N. Okada and Y. Okada, PRD 75, 2007. ～Contents ～ Little Higgs Scenario Little Higgs signals at LHC & ILC Summary

  2. 1/11 1. Little Hierarchy Scenario EW Observables Corrections to mh Kolde & Murayama, hep-ph/0003170 Barbieri & Strumia, 1998 • If coefficient ci is O(1), • ΛSM > O(10)TeV (mh = 120 GeV) • When the tuning < 10%, • ΛSM < O(1)TeV (mh = 120 GeV) Little Hierarchy Problem E ??? 10 TeV 1 TeV Need some mechanism to control the Higgs mass!

  3. 2/11 1. Little Hierarchy Scenario Little Higgs Scenario ・ Higgs boson = Pseudo NG boson ・ Explicit breaking = Collective symmetry breaking E Generation of mh Origin of mh = Interactions which break G. New Physics with G ( ⊃ Gauge group ), which is slightly broken 10 TeV Usual breaking: When the interaction “L1“ breaks the symmetry G, and generates mh, then (mh)2～ (ΛSM)2/(16π2) ～ (1 TeV)2 (1-loop diagrams) SSB: G  G’, where G’ ( ⊃ SU(2) x U(1)Y ) 1 TeV Electroweak breaking SU(2) x U(1)Y U(1)EM (Standard Model) 100 GeV

  4. 2/11 1. Little Hierarchy Scenario Little Higgs Scenario ・ Higgs boson = Pseudo NG boson ・ Explicit breaking = Collective symmetry breaking E Generation of mh Origin of mh = Interactions which break G. New Physics with G ( ⊃ Gauge group ), which is slightly broken 10 TeV Collective symmetry breaking: When the Interactions “L1“ & “L2“ (partially) break G, and the Higgs boson is “pseudo” NG boson when both interactions exist, (mh)2～ (ΛSM)2/(16π2)2 ～ (100 GeV)2 (2-loop diagrams) SSB: G  G’, where G’ ( ⊃ SU(2) x U(1)Y ) 1 TeV Electroweak breaking SU(2) x U(1)Y U(1)EM (Standard Model) 100 GeV

  5. 3/11 1. Little Hierarchy Scenario Diagrammatic view point ・ Global symmetry imposed ・ Collective sym. breaking New particles introduced. (Little Higgs partners) W,Z WH,ZH + h h t t T h + h + h t T Quadratically divergent corrections to mh are completely cancelled at 1-loop level! Constructing models SM Nonlinear sigma model E 100 GeV 10 TeV 1 TeV

  6. 4/11 1. Little Hierarchy Scenario - - - H SU(5)  SO(5) [SU(2)xU(1)]2SU(2)xU(1) - - - H H - - - - - - T+ Triplet Lagrangian – F2/4 + LYukawa– V(H, F) + Kinetic terms of fermions No quadratically divergent |H|2 term at 1-loop level.

  7. 4/11 1. Little Hierarchy Scenario H. C. Cheng, I. Los, J. High Energy Phys. (2003, 2003) - - - H T-parity - H - - H - - - - - - T– T+ Triplet Constraints from EWPM Littlest Higgs model suffers from EWP constraints. ～ Imposition of the Z2-symmetry (T-parity) ～ 1. SM particles & Top partner T+ are even 2. Heavy Gauge bosons are odd. 3. T-odd partners of matter fields introduced.

  8. 4/11 1. Little Hierarchy Scenario H. C. Cheng, I. Los, J. High Energy Phys. (2003, 2003) - - - H T-parity - H - - H - - - - - - T– T+ Triplet Constraints from EWPM • Model Parameters of the LHT • f : VEV of the SU(5)  SO(5) breaking • l2: Mass of the top-partners (in units of f) • kx: Mass of the T-odd partner of “x”(in units of f) • Higgs mass mh is treated as a free parameter

  9. 4/11 1. Little Hierarchy Scenario H. C. Cheng, I. Los, J. High Energy Phys. (2003, 2003) Masses of new particles are proportional to f. O (f) O (v) Masses of SM particles are proportional to v. Constraints from EWPM • Model Parameters of the LHT • f : VEV of the SU(5)  SO(5) breaking • l2: Mass of the top-partners (in units of f) • kx: Mass of the T-odd partner of “x”(in units of f) • Higgs mass mh is treated as a free parameter

  10. 5/11 1. Little Hierarchy Scenario Lightest T-odd Particle is stable due to the T-parity conservation.  Little Higgs Dark Matter! (Heavy photon in the LHT) J. Hubisz, P. Meade, Phys. Rev. D71, 035016 (2005) Main annihilation mode:AH AH  h  WW or ZZ 1. AHAHh vertex is given by the SM gauge coupling. 2. Annihilation cross section depends on mAH & mh.  Relic abundance of AH: Wh2(mAH(f), mh) Little Higgs dark matter is singlet and spin 1 particle. The dark matter mass:80-400 GeV The Higgs mass:110-800 GeV Wh2 of dark matter Asano, S.M, N.Okada, Y.Okada (2006)

  11. 6/11 1. Little Hierarchy Scenario Constraints from EWPM? U-branch

  12. 6/11 1. Little Hierarchy Scenario Constraints from EWPM? L-branch

  13. 6/11 1. Little Hierarchy Scenario Constraints from EWPM? L-branch Representative point f = 580 GeVl2 = 1.15 mh = 134 GeVmT+ = 834 GeVmT-= 664 GeV mAH= 81.9 GeVmWH = 368 GeVmZH = 369 GeV 1. Masses of top partners are about (or less than) 1 TeV!  copiously produced at the LHC. 2. Masses of heavy gauge bosons are several hundred GeV!  can be produced at the ILC.

  14. 7/11 2. Littlest Higgs Signals at LHC & ILC Top partner productions LHC is a hadron collider, sothat colored new particlesare copiously produced!  T+ & T- productions! MadGraph/Event (Event generation) PYTHIA (Hadronization) PDG4 (Detector Response) S.M., T. Moroi, K. Tobe, Phys.Rev.D78 (2008) T+ pair production Reconstructing twoT+-system, T+(lep) & T–(had) Determination of T+ Mass(with ±20 GeV uncertainty)

  15. 7/11 2. Littlest Higgs Signals at LHC & ILC Top partner productions LHC is a hadron collider, sothat colored new particlesare copiously produced!  T+ & T- productions! MadGraph/Event (Event generation) PYTHIA (Hadronization) PDG4 (Detector Response) S.M., T. Moroi, K. Tobe, Phys.Rev.D78 (2008) Single T+ production # of the signal depends on NP! (σ determined with 20% accuracy.) Reconstructing bW system

  16. 7/11 2. Littlest Higgs Signals at LHC & ILC Top partner productions LHC is a hadron collider, sothat colored new particlesare copiously produced!  T+ & T- productions! MadGraph/Event (Event generation) PYTHIA (Hadronization) PDG4 (Detector Response) H1 H2 S.M., T. Moroi, K. Tobe, Phys.Rev.D78 (2008) T- pair production 200 100 0 Top reconstruction via hemisphere analysis. End points of MT2 depend on mT- & mAH (within about 20 GeV accuracy.) S.M., Nojiri, Nomura (2007)

  17. 8/11 2. Littlest Higgs Signals at LHC & ILC From T+ pair prod. From T+ single prod. From T- pair prod. l2 3s 1s f (GeV) f = 580 ± 33 GeV  Cosmological connections

  18. 9/11 2. Littlest Higgs Signals at LHC & ILC Heavy gauge boson productions ILC is a e+e-collider, so that heavy particles are produced with clean environment.  WH, ZH, AH productions! Physsim (Event generation) PYTHIA (Hadronization) JSF Q-sim. (Detector Response) E. Asakawa, M. Asano, K. Fujii, T. Kusano, S. M., R. Sasaki, Y. Takubo, and H. Yamamoto, PRD79, 2009. ZHAH production @ 500 GeV 500 fb-1 s = 1.9 fb mAH= 83.2 ±13.3 GeV mZH = 366. ±16. GeV  f = 576. ±25. GeV Energy distribution of h  End points depend on mAH & mZH

  19. 9/11 2. Littlest Higgs Signals at LHC & ILC Heavy gauge boson productions ILC is a e+e-collider, so that heavy particles are produced with clean environment.  WH, ZH, AH productions! Physsim (Event generation) PYTHIA (Hadronization) JSF Q-sim. (Detector Response) E. Asakawa, M. Asano, K. Fujii, T. Kusano, S. M., R. Sasaki, Y. Takubo, and H. Yamamoto, PRD79, 2009. ZHAH production @ 1 TeV 500 fb-1 s = １２１ fb mAH= 81.58 ±0.67 GeV mWH= 368.3 ±0.63 GeV  f = 580±0.69 GeV Energy distribution of W  End points depend on mAH & mZH

  20. 10/11 2. Littlest Higgs Signals at LHC & ILC Probability density Simulation results + Higgs mass Planck WMAP ILC(1000) LHC Annihilation X-section <sv>(mAH, mh)  WDMh2 ILC(500) Probability density of the dark matter relics WDMh2 LHC: Abut 10% accuracy (Model-dependent analysis) ILC(500): Better than 10% accuracy (Model-independent analysis) ILC(1000): 2% accuracy!! (Model-independent analysis)

  21. 11/11 3. Summary • Little Higgs model with T-parity is one of attractive scenario describing New Physics at TeraScale. • It contains a candidate for cold dark matter whose stability is guaranteed by the T-parity (Little Higgs dark matter). • The property of the dark matter can be investigated at collider experiments such as LHC & ILC. • At LHC, top partners can be detected. From their data, the property of the dark matter can be estimated with a model dependent way. • At ILC with s1/2 = 500 GeV, the property of the dark matter can be determined with model-independent way. Also, the relic abundance can be determined with the accuracy comparable to the WMAP. • AT ILC with s1/2 = 1 TeV, the property of the dark matter can be determined very accurately. For instance, the relic abundance will be determined with the accuracy comparable to PLANCK experiment.

  22. Back Up

  23. – F2/4 + LYukawa– V(H, F) + Kinetic terms of fermions The LH Lagrangian Non-linear s field Pseudo NG bosons Breaking directions

  24. – F2/4 + LYukawa – V(H, F) The LH Lagrangian Gauge interactions [SU(2) x U(1)]2 Gauge couplings: g1, g’1, g2, g’2

  25. – F2/4 + LYukawa – V(H, F) The LH Lagrangian Top Yukawa interactions tR tL Top Yukawa: l1 U quark mass: l2

  26. 4 gauge bosons: B1, W1 , B2, W2 Σ= (24 – 10) pions : Particle contents in Gauge, Higgs, and top sectors SM gauges : A, W±, Z Heavy gauges : AH, WH±, ZH SM Higgs : h Triplet Higgs : Φ After breakings Parameters g1, g’1, g2, g’2 SM top quark : t , Heavy top : T = (U, UR)T l1, l2 f

  27. Little Higgs Dark Matter Lightest T-odd Particle is stable due to the T-parity conservation.  Little Higgs Dark Matter! (Heavy photon in the LHT) [J. Hubisz, P. Meade, Phys. Rev. D71, 035016 (2005) ] Main annihilation mode:AH AH  h  WW or ZZ. 1. AHAHh vertex is given by the SM gauge coupling. 2. Annihilation cross section depends on mAH & mh.  Relic abundance of AH: Wh2(mAH(f), mh) Wh2(mAH(f), mh) When mh < 150 GeV, then 550 < f < 750 GeV. Masses of heavy gauge bosons are several hundred GeV.  can be produced at ILC. Masses of top partners are about (or less than) 1 TeV  copiously produced at LHC. [Asano, S.M, N.Okada, Y.Okada (2006)]

  28. Representative point for simulation study Considering EW precision & WMAP constraints [J.Hubisz, P. Meade, A. Noble, M. Perelstein, JHEP0601 (2006)] (1) Observables (mwsinqW, Gl, WDMh2) vs. Model parameters (f, l2, mh) (2) 2mh2/mt > O(0.1-1), where mt is the top-loop contribution to mh. f = 580 GeVl2 = 1.15 mh = 134 GeVmAH = 81.9 GeVmWH = 368 GeVmZH = 369 GeVmT+ = 834 GeVmT-= 664 GeV mF = 440 GeV (mLH = 410 GeV)

  29. T+ pair production at the LHC - SM BG: tt–production! (460 pb) At the parton levelSignal = bbqqlν ~ Strategy to reduce BG ~ - - • Reconstruct Two T+-system: T+(lep) & T–(had) using the fact that the missing momentum • pT is due to the neutrino emission and • (pl + pν)2 = mW2. There are 6-fold ambiguity in the reconstruction of T+-system. • The combination to minimize ~ Output ~ Distribution of

  30. T+ pair production at the LHC ~ Cut used in the analysis ~ ~ Results ~ ~ Discussion ~ The distributions have distinguishable peaks at around the T+ mass. SM BG are well below the signal.  From the distribution, we will be able to study the properties of T+.

  31. T+ pair production at the LHC ~ Accuracy of the mT+ determination ~ We consider the bin Then, we calculate the # of events in the bin as a function of with being fixed. The peak of the distribution is determined by maximizing the # of events in the bin. We applied the procedure for ~ Conclusion ~ The difference between the position of the peak and the input value of mT+ is, typically, 10-20 GeV! ~ Results ~

  32. T+ single production at the LHC - SM BG: tt & single t productions! At the parton levelSignal = bqlν ~ Strategy to reduce BG ~ Existence of very energetic jet (b from T+)! With the leading jet, reconstruct T+-system.There are 2-fold ambiguity to reconstructneutrino momenta  & Reject events unless is small. Jet mass is also used to reduce the BG. ~ Output ~ Distribution of

  33. T+ single production at the LHC ~ Cut used in the analysis ~ ~ Results ~ ~ Discussion ~ Single T+ production occurs not through a QCD process but through a EW process (e.g. W-exchange). Distributions have distinguishable peaks at around the T+ mass when sin2βis large enough!  From the cross section, we will be able to determine sinβ.

  34. T+ single production at the LHC ~ Accuracy of sinβ determination ~ ~ Conclusion ~ We use the side-band method to extract the # of the single production events, (L) (C) (R) after imposing the cuts. Then, cross section for the single T+ production can be obtained from the # of events in the signal region. The cross section, which is proportional to sin2β, will be determined with 10-20%. Parameter “sinβ”, which is given by a combinationof f & λ2, will be determined with 5-10% accuracy! ~ Results (Point 2) ~

  35. T– pair production at the LHC H1 H2 T– decays into t + AH with 100 % branching ratio - SM BG: tt–production! (460 pb) At the parton levelSignal = (bqqAH)×2 ~ Strategy to reduce BG ~ 1. Large missing momentum is expected in the signal event due to dark matter emissions. 2. Use the hemisphere analysis to reconstruct the top quark [S.M., Nojiri, Nomura (2007)]. 3. Since AH is undetectable, direct masurements of T– & AH are difficult.  MT2 variable! ~ Output ~ Distribution of MT2

  36. T– pair production at the LHC ~ Cut used in the analysis ~ ~ Results (Point 2) ~ 0 100 200 ~ Discussion ~ “MT2 variable” is a powerful tool to determine mT+ and mAH, which is defined by with being the postulated AH mass. Then, the end point of MT2 distribution is

  37. T– pair production at the LHC ~ Accuracy MT2(max) determination ~ ~ Conclusion ~ End-point of the distribution of MT2 is determined by a combination of mT+ , mAH, and the postulate mass . By looking at the position of the end-point with an appropriate value of , it is possible to get information of mAH & mT+! We have also checked that there is no contamination of the BG around End-point! Using the distribution of the MT2 with , the upper end-point will be determined with 10-20 GeV accuracy (at Point 2)! ~ Results (Point 2) ~ With the use of quadratic function to estimate the end-point, using using when . Theoretically, the end-point is 664 GeV.

More Related