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T パリティーを課した Littlest Higgs 模型における暗黒物質の探索

T パリティーを課した Littlest Higgs 模型における暗黒物質の探索. 　総研大　　 浅野雅樹. Collaborated with 岡田宣親　岡田安弘　松本重貴. hep-ph/0602157. http://map.gsfc.nasa.gov/. I. ntroduction. The existence of Non-baryonic cold dark matter is established (by WMAP ). cold dark matter candidate.

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T パリティーを課した Littlest Higgs 模型における暗黒物質の探索

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  1. Tパリティーを課した Littlest Higgs 模型における暗黒物質の探索 　総研大　　浅野雅樹 Collaborated with 岡田宣親　岡田安弘　松本重貴 hep-ph/0602157

  2. http://map.gsfc.nasa.gov/ I ntroduction The existence of Non-baryonic cold dark matter is established (by WMAP) cold dark matter candidate • Supersymmetric Model with R-parity(neutralino) ・・・ • Little Higgs Model with T-parity (heavy photon) • Neutral • Stable • Massive (100 GeV – 1TeV) (Weakly Interacting Massive Particle) WIMP There is no WIMP in the Standard Model (SM) beyond SM ( WIMP ) H-C.Cheng and I.Low (‘03) In the littlest Higgs model with T-parity, We have studied the possibility to detect the dark matter signal in future experiments (PAMELA and AMS-02) . (byusing e+)

  3. loops = + tree I I Hierarchy Problem in SM The hierarchy Problem is related to quadratic divergence to the Higgs mass term. ntroduction to the Little Higgs Mechanism The Higgs mass receives huge radiative corrections. In contrast the mass is at the electroweak scale . δm2～Λ2 :cutoff scale m02 +δm2 To solve the problem, many scenarios have been proposed so far. (such as supersymmetry) Little Higgs models are a new possibility for physics at TeV energies.These models can solve the hierarchy Problem. N. Arkani-Hamed, A. G. Cohen and H. Georgi(‘01)

  4. Uem(1) [SU(2)×U(1)]2 SU(2)×U(1) WH W h h h h – g2 g2 In the Little Higgs Model We can realize the Higgs boson asthepseudo Nambu-Goldstone boson of a broken symmetry in a way which ensures that quadratic divergences to the Higgs mass term completely vanish at one-loop level. For example, the quadratic divergences in the gauge boson loops is canceled by contribution from the extra heavy gauge boson loops. + Littlest Higgs Model SU(5)/SO(5) gauge group 〈 h 〉 VEV f ~ O(1)TeV New particles WH,BH,ΦH,tH are introduced.

  5. SM particle ZH I ntroduction to the T-parity Original little Higgs models are still strongly constrained by the electroweak precision measurements (EWPM). This is mainly due to the contributions to electroweak observables from new heavy gauge bosons. As a result, masses of new particles have to be raised, and fine-tuning of the Higgs boson mass is reintroduce. To solve the problem, T-parity has been introduced. T-parity The underlying idea of T-parity is to assign all SM particles even parity, and all new particles odd parity. Thanks to the symmetry, the masses of new particles can be lighter.

  6. SU(5) [SU(2)×U(1)]2 SO(5) SU(5) / SO(5) L ittlest Higgs model with T-parity The littlest Higgs model is based on a non-linear sigma model describing SU(5)/SO(5) symmetry breaking. Symmetry breaking There are 14 NG bosons SU(5) ⊃ [SU(2)×U(1)]2 (gauged) SO(5)⊃SU(2)×U(1) absorbed by heavy gauge bosons (SM) Little Higgs doublet triplet Higgs boson under SU(2)L

  7. The non-linear sigma model field is f is the VEV Higgs isexact NG boson under either SU(3) gauge couplings (SU(2), U(1)) Kinetic term of non-linear sigma model W gauge boson heavy W gauge boson B gauge boson heavy B gauge boson

  8. T-parity Spectrum 10 T-even T-odd Φ WH , ZH 1 (TeV) h AH W, Z 0.1 B1(W1) ⇔ B2(W2) Π⇔－ΩΠΩ Ω= diag.(1,1,–1,1,1) Due to the T-parity, the lightest T-odd particlebecomesstableand a candidate of the dark matter. And the mass is only determined by breaking scale f. Lightest T-odd

  9. ~mh2/v ~g’2/v ~g’2 main ~g’2/v ~mW2/v If mAH > mh main R elic abundance of dark matter Here, We compare the relic abundance of this dark matter candidate with WMAP observation. J.Hubisz and P.Meade (‘05) Dark matter annihilation The dark matter candidate annihilates mainly into weak gauge bosons. In this cross section, there are s-channel poles. contour plot of the relic abundance

  10. mAH (GeV) U-branch mh (GeV) L-branch S-channel pole linemh = 2mAH f (TeV) Theshaded areais the allowed region for WMAP at 2σlevel

  11. Relic density １ ∝ The relic density is inversely related to the dark matter annihilation cross section. Therefore,the allowed region from the WMAP observation lies at either side of s-channel pole line. cross section The Relic density depends only onmAH and mh because mAH ~ f. Therefore, the U-branch and the L-branch can be expressed as a function of the mAH and mh. D etection of the dark matter We discuss the possibility to detect this dark matter signal in the future experiments (PAMELA and AMS-02). Indirect detection by using e+ Indirect detections are to detect the cosmic rays (e+,γ ,p- ,ν) produced in the dark matter annihilation. Here we use e+ because astrophysical ambiguity on the signal (and background) is small compared to other indirect detections.

  12. e+ Dark matter annihilates into e+ in the galactic halo. And the signal is observed as the e+ excess in cosmic rays. We calculate the expected flux of the positrons at the earth from the annihilation. In evaluation of the flux, We need to take into account the propagation of positrons through the galaxy. 1. We estimate the production rate of e+ from the annihilation. Halo Dark matter Annihilation e+

  13. e+travel in our galaxy under the influence of a tangled magnetic field. 2~5 ∝ Sun 2. We estimate the positron flux at the earth by solving the diffusion equation for the propagation. In the flux, there is a parameter which is called Boost Factor (BF). BF represents the effect of the inhomogeneity in the local dark matter distribution. Effect of inhomogeneity Boost Factor Number density of positrons per unit energy ( in the inflationary universe ) V.Berezinsky et al (’03)

  14. BF = 5 positron fraction in 7 sample points (On the allowed region for WMAP)

  15. Projectederror bar in a certain case In order to discuss the possibility for detection of the dark matter signal in the future experiments (PAMERA and AMS-02), we perform the χ2-analysis in the whole region. PAMELA AMS-02 χ2 is proportional toBF2 D.Hooper & J.Silk (‘05)

  16. Contour plot of χ2 In the AMS-02 with BF = 2 In the PAMELA with BF = 5 χ2 = 33.9 95% confidence level These figures represent the χ2 in each experiments. The constraint from the WMAP observation is also shown as a shaded region

  17. χ2 plot ( along with the U- and L-branch ) within WMAP constraint 120 120 300 150 χ2 depends only on BF and mh because the dark matter does not annihilate into a pair of Higgs within WMAPconstraint. C onclusion

  18. PAMELA f < 830GeV (mAH < 120GeV ) BF > 5 AMS-02 Wide range of the parameter space including the region BF = 1 95% C. L. contour within WMAP constraint f (TeV) The region above the line can be distinguished from the background in each experiment. Contour lines of the upper branch and the lower branch are almost degenerate in this parameter space.

  19. S ummary • We have studied the possibility to detect the AH dark matter in the littlest Higgs model with T-parity. • In the PAMELA experiment , the dark matter signal may be detected when f < 830GeV (mAH < 120GeV ) and BF > 5 . • In AMS-02 experiments, the dark matter signal may be detected even if there is no enhancement from the boost factor. Direct detection and Indirect detection viaγ ray （A.Birkedal et al ‘06）

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