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Optimization of a neutrino factory for non-standard neutrino interactions

Optimization of a neutrino factory for non-standard neutrino interactions. IDS plenary meeting RAL, United Kingdom January 16-17, 2008 Walter Winter Universität Würzburg. Contents. In collaboration with Joachim Kopp and Toshihiko Ota. Introduction Our setup Main questions:

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Optimization of a neutrino factory for non-standard neutrino interactions

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  1. Optimization of a neutrino factoryfor non-standard neutrino interactions IDS plenary meeting RAL, United Kingdom January 16-17, 2008Walter Winter Universität Würzburg

  2. Contents In collaborationwith Joachim Kopp andToshihiko Ota • Introduction • Our setup • Main questions: • What does the silver channel help? • How small can the muon energy be? • Standard versus non-standard baseline optimization • Summary IDS-NF @ RAL - Walter Winter

  3. Non-standard neutrino interactions • Consider effective four-point interactions • This leads to a Hamiltonian for n propagation: matter potential: • For antineutrinos: H  H*, aCC  -aCC IDS-NF @ RAL - Walter Winter

  4. NSI constraints (ISS Physics report, arXiv:0710.4947) • Limits depend on chirality and fermion • Neutrino propagation in principle sensitive to 3eu+3ed+ee • We ignore potential production and detection effects, which can be parameterized similarly! IDS-NF @ RAL - Walter Winter

  5. Relevant parameters for a NF Relatively strong constraints Complex numbers Real number Uninteresting:limited by matterdensity uncertainty Weak constraints IDS-NF @ RAL - Walter Winter

  6. Our setup: close to IDS baseline! • Two detectors at L1 and L2, 50 kt each • 50% E0.5 energy resolution • Backgrounds 0.001/E2 • 2.5% signal uncertainty, 20% BG uncertainty • 4 yr + 4 yr running time • 1021 useful muon decays/year/detector! • Em=50 GeV, unless stated otherwise New analysis (diff. Lm) Our detector (Cervera@Golden 07) Old analysis/det. • Silver channel:10 kt Silver* fromhep-ph/0606119(Autiero et al ECC with 5xSG, 3xBG) IDS-NF @ RAL - Walter Winter

  7. Performance indicators used • Definition of eab sensitivity similar to q13 sens.: Largest fit |eab| which fits a true eab=0 • Corresponds to a conservative case discovery potential • All oscillation parameters, NSI phases marginalized over (exceptions: for ett, which is real, or if eab is assumed to be real) • Typically only one or two NSI parameters considered, such as |eet|, ett, |eet|-ett-plane IDS-NF @ RAL - Walter Winter

  8. NSI with magic baseline 3000 km arXiv:0709.1980 • Combing the two baselines reduces the impact of correlations drastically(only real eet assumed!) • Does one still need the silver channel in that case? 7000 km Combined Close to worst case for degeneracies: dCP=3p/2, sin22q13=0.001 IDS-NF @ RAL - Walter Winter

  9. Correlations at magic baseline • Including NSI, the magic baseline is not exactly correlation/degeneracy-free • Example: Approximation • aCC ~ E: Standard term drops as 1/E4, NSI-Term as 1/E3 High energies important for NSI! IDS-NF @ RAL - Walter Winter

  10. Comparison to our simulation (1) Our simulation,similar setup Our simulation,our setup Our simulation + our setup,all osc. params marginalized arXiv:0709.1980 3000 km Preliminary 7000 km Combined Only q13 and dCP marginalized! IDS-NF @ RAL - Walter Winter

  11. Comparison to our simulation (2) 3000 km +7000 km +Silver*@3000km 3000 km +7000 km Preliminary 3000 km + 7000 kmSilver*@3000km +Disappearance 3000 km +7000 km +Disappearance Disappearance important for ett, emt! IDS-NF @ RAL - Walter Winter

  12. When does the silver channel help… in a two baseline setup? • Assume oneNSI parameterat first, such as eet • Fix golden detectors • Where is the optimalsilver baseline? • Place Silver* at golden baseline 1!Em >= 50 GeV! Preliminary 0.01 0.004 Golden detector 1 = Silver baseline IDS-NF @ RAL - Walter Winter

  13. Minimum muon energy? • Higher muon energy helps; low-E NF not an option • Silver channel: Not relevant for IDS baseline; helps for Em ~ 50 GeV IDS baseline? High-E NF IDS baseline? High-E NF Preliminary IDS-NF @ RAL - Walter Winter

  14. What if more parameters? • Marginalize over phase of eet as well: • Absolute limits: |ett| < 0.03, |eet| < 0.006 (3s)Two orders of magnitude improvement of current bounds! 3000km+7000km 3000km+7000km+Silver*@3000km Preliminary IDS-NF @ RAL - Walter Winter

  15. Standard versus non-standard optimization • Obviously, the main NSI sensitivity comes from the golden and disappearance channels • Changing the golden baselines will affect the NSI sensitivities • What if there is no silver channel, do the standard and non-standard optimizations coincide? • Perform optimizations in L1-L2-space IDS-NF @ RAL - Walter Winter

  16. Standard optimization revisited • All regions:Sensitivity for sin22q13>10-4.2 (5s) for the shown performance indicator • True dCP chosen close to worst case • Robust optimum for ~ 4000 + 7500 km(not <= 3000 km!) Preliminary IDS-NF @ RAL - Walter Winter

  17. NSI optimization: one parameter • Similar to matter effects (which increase with baseline!), NSI sensitivities want one very long baseline Preliminary IDS-NF @ RAL - Walter Winter

  18. Combined optimization: Example • 4000 + 7500 kmconsistent withNSI optimization • But: In general,choose both baselines rather longer than shorter! NSI example(dCP=p/2, sin22q13=0.01) Preliminary Standard opt: combined IDS-NF @ RAL - Walter Winter

  19. Summary and conclusions • The leading NSI sensitivity comes from the golden + disappearance channels • The silver channel might help if Em > 40 GeV  Return to high-E NF for IDS baseline? • A low-E NF (Em << 20 GeV) probably has very little NSI sensitivity beyond the current limits • The currently used IDS baseline setup 4000 km + 7500 km is consistent for both standard and non-standard effects; the baselines be rather longer than shorter! • NSI are important to establish the physics case for a very long baseline IDS-NF @ RAL - Walter Winter

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