1 / 18

3+2 Neutrino Phenomenology and Studies at MiniBooNE

3+2 Neutrino Phenomenology and Studies at MiniBooNE. Georgia Karagiorgi, Columbia University. PHENO 2007 Symposium May 7-9, 2007 U. Wisconsin, Madison. Outline. Motivation for 3+2 models 3+2 phenomenology and oscillation formalism

pklein
Download Presentation

3+2 Neutrino Phenomenology and Studies at MiniBooNE

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. 3+2 Neutrino Phenomenology and Studies at MiniBooNE Georgia Karagiorgi, Columbia University PHENO 2007 Symposium May 7-9, 2007 U. Wisconsin, Madison

  2. Outline • Motivation for 3+2 models • 3+2 phenomenology and oscillation formalism • The MiniBooNE result and experimental constraints for 3+2 models • CP violation studies in 3+2 models and prospects for CPV measurement at MiniBooNE • Current status of 3+2 analysis and future plans • Conclusions G. Karagiorgi et al., “Leptonic CP violation studies at MiniBooNE in a (3+2) sterile neutrino oscillation hypothesis,” Phys. Rev. D. 75, 013011 (2007) [hep-ph/0609177]. Georgia Karagiorgi, Columbia U.

  3. The LSND Signal Δm2LSND ~ 0.1- 10 eV2 + small mixing Δm2LSND >> Δm2atm>> Δm2sol one option:3 active + n “sterile” neutrinosother options: neutrino decay, extra-D, etc. Georgia Karagiorgi, Columbia U.

  4. 3+2 Model Phenomenology 3 active + 2 sterile neutrinos • lightsterile neutrinos • they can interact thru non-standard weak couplings • they have very small active flavor content (Ue4,…, Ue5,…) •  can participate in neutrino oscillations νe νμ ντ νs increasing m2(not to scale) Why n=2? 3+1 models: SBL and LSND marginally consistent with each other 3+2: next natural step… [M. Sorel, et al. hep-ph/0305255] Georgia Karagiorgi, Columbia U.

  5. 3+2 Model Phenomenology GUT’s Mohapatra, Nasri, & Yu [hep-ph/0505021] De Gouvea, Jenkins, & Vasudevan [hep-ph/0608147] Extra-D Pas, Pakvasa, & Weiler [hep-ph/0504096] Ma, Rajasekaran, & Sarkar [hep-ph/0006340] SUSY Kang, & Li [hep-ph/0501101] Dvali, & Nirb [hep-ph/9810257] Georgia Karagiorgi, Columbia U.

  6. 3+2 Neutrino Oscillation Formalism General neutrino oscillation formula: P(νανβ) = δαβ – 4ΣRe (U*αiUβiUαjU*βj)sin2xij + 2 ΣIm (U*αiUβiUαjU*βj) sin2xij P(νμνe) = 4|Uμ4|2|Ue4|2sin2x41 + 4|Uμ5|2|Ue5|2sin2x51 + + 8 |Uμ5||Ue5||Uμ4||Ue4|sinx41sinx51cos(x54+φ45) xij = 1.27Δm2ij L/E Assumptions for 3+2 model analysis: approximatem1 = m2 = m3 = 0 * two independent mass splittings:Δm241,Δm251 four moduli:|Ue4|,|Uμ4|,|Ue5|,|Uμ5| one CPV phase:φ54 = arg(U*μ5 Ue5 Uμ4 U*e4) * This allows for 6  1 CPV phase in a (3+2) hypothesis (3  0 CPV phases in a (3+1) hypothesis) (1  0 CPV phases in a (3+0) hypothesis) 3+2 model = most minimal model for CPV studies! Georgia Karagiorgi, Columbia U.

  7. First Results from MiniBooNE MiniBooNE result excludes the LSND 90%CL allowed regionat > 90% CL… “A Search for Electron Neutrino Appearance at the Δm2 ~ 1eV2 Scale,” The MiniBooNE Collaboration [hep-ex/0704.1500]. Georgia Karagiorgi, Columbia U.

  8. First Results from MiniBooNE …MiniBooNE result assumes: CP-conserving, 2-neutrino oscillation scenario E > 475 MeV Excess of νe events at low energies: Currently investigating if this is a detector effect, or SM background… Could be a manifestation of beyond the SM physics… For more information on this, see talk by Chris Polly Georgia Karagiorgi, Columbia U.

  9. Experimental Constraints We are interested in: • studying the compatibility of null SBL results with LSND and MiniBooNE results in a 3 active + 2 sterile neutrino hypothesis • constraining the3+2 model parameters sin2θ constraint (90%CL) Georgia Karagiorgi, Columbia U.

  10. Combined NSBL+LSND+MiniBooNE • 3+2 analysis (including MB νebackground disappearance) • and compatibility tests are currently in progress… • Recent studies: • Leptonic CP violation studies at MiniBooNE in a 3+2 sterile neutrino oscillation hypothesis • Expected oscillation probability at MiniBooNE • Potential of CP-violation measurement at MiniBooNE [hep-ph/0609177] Dataset: NSBL + LSND only (no atmospheric or solar experiment data) + Super-K atm. constraint Georgia Karagiorgi, Columbia U.

  11. Oscillation Analysis for CPV Studies at MiniBooNE P(νμνe) = 4|Uμ4|2|Ue4|2sin2x41 + 4|Uμ5|2|Ue5|2sin2x51 + + 8 |Uμ5||Ue5||Uμ4||Ue4|sinx41sinx51cos(x54+φ45) • Generate masses and mixing parameters (models): • 0.1eV2≤Δm241, Δm251≤ 100eV2 Δm251 ≥Δm241 • |Ue4|, |Uμ4|,|Ue5|,|Uμ5| Uei2 + Uμi2≤ 0.5, Uα42 + Uα52≤ 0.5 • atmospheric constraint: dμ = ½ - √(1-4A)/2 where A = (1 - |Uμ4|2- |Uμ5|2)(|Uμ4|2+ |Uμ5|2) + |Uμ4|2|Uμ5|2 CP violation option: Fix φ54=0,π, or allow to vary within (0,2π) • Calculate expected oscillation probabilities in neutrino and anti-neutrino running mode at MiniBooNE (using expected full νμ νetransmutation rates) • Determine allowed regions by Gaussian approximation Importance sampling via Markov chain: P(xi xi+1) = min{1,exp[-(χ2i+1-χ2ι)/Τ]} xi+1 = xi + e Georgia Karagiorgi, Columbia U.

  12. Oscillation probability expected at MiniBooNE CP-conserving 3+2 models CP-violating 3+2 models 90%CL 99%CL Best fit models:CPC: χ2/dof = 141.4/145CPV: χ2/dof = 140.8/144 Georgia Karagiorgi, Columbia U.

  13. Potential observation of CP-violation at MiniBooNE All CP-violating phase values allowed at 99%CL by the NSBL+LSND data are measurable at MiniBooNE Small degrees of CPV preferred Large asymmetries allowed, but not required 90%CL 99%CL Georgia Karagiorgi, Columbia U.

  14. First global fit results χ2PG = 17.5 , PG = 1.5x10−3 (no MB) χ2PG = 25.1 , PG = 4.8x10−5 (MB300) Best fit parameters for global fit with full MiniBooNE E range: Δm241 = 0.87eV2 x2min /dof = 104.4/(109-7) Δm251 = 1.91eV2 gof = 41% cpv-phase = 1.44π Analysis by Maltoni & SchwetzFig. 7 [hep-ph/0705.0107] Georgia Karagiorgi, Columbia U.

  15. Potential observation of CP-violation at MiniBooNE MiniBooNE expected oscillation probability asymmetry based on calculated best fit model parameters from hep-ph/0705.0107 global 3+2 analysis (MB300 and MB475) MB300 Ap/p = -0.448 φ45 = 1.44π MB475 Ap/p = -0.207 φ45 = 1.64π Georgia Karagiorgi, Columbia U.

  16. First global fit results • 3+2 neutrino models: • provide a good fit to LSND and the recent MB data • can account for the low energyevent excess in MB • However: • there is significant tensionbetween appearance and disappearance data (according to the PG test at the level of 3σ for MB475 and 4σ for MB300). Note: analysis done without full MiniBooNE error matrix MB signal prediction from best fit points from SBL appearance data (LSND, KARMEN, NOMAD, MB) in a 3+2 oscillation analysis Maltoni & SchwetzFig. 3 [hep-ph/0705.0107] Georgia Karagiorgi, Columbia U.

  17. Our next 3+2 steps… More detailed combined NSBL + LSND + MiniBooNE 3+2 oscillation analysis and compatibility tests, that take into consideration: • Full MiniBooNE error matrix • Disappearance of MiniBooNE νe background Georgia Karagiorgi, Columbia U.

  18. Conclusions • Original motivation: accommodate null SBL and LSND results within the framework of neutrino oscillations • MiniBooNE data: key in addressing the viability of 3+2 models with sterile neutrinos • Leptonic CP-violation possibility opened up in the 3+2 sterile neutrino hypothesis could have large measurable effects at MiniBooNE Georgia Karagiorgi, Columbia U.

More Related