1 / 25

The quest for q 13 : Parameter space and performance indicators

The quest for q 13 : Parameter space and performance indicators. Proton Driver General Meeting At Fermilab April 27, 2005 Walter Winter Institute for Advanced Study, Princeton. Contents. Introduction Simulation of future experiments Performance indicators for q 13

haley-bradshaw
Télécharger la présentation

The quest for q 13 : Parameter space and performance indicators

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. The quest for q13: Parameter space and performance indicators Proton Driver General Meeting At Fermilab April 27, 2005 Walter Winter Institute for Advanced Study, Princeton

  2. Contents • Introduction • Simulation of future experiments • Performance indicators for q13 • What is “Fraction of dCP”? • PD News: Neutrino oscillation landscapes • Some implications: Examples for q13 cases • Summary PD General Meeting - Walter Winter

  3. ( ) ( ) ( ) = x x Neutrino mixing Use standard parameterization - as for CKM matrix: (sij = sin qij cij = cos qij) • Three mixing angles q13, q12,q23; one CP phase dCP • Difference to quarks: Two mixing angles large: q12,q23 PD General Meeting - Walter Winter

  4. Neutrino mass • From oscillations: We know that neutrinos have mass! • Dirac or Majorana? • Absolute neutrino mass scale? Now: < eV • Mass schemes: Degenerate or hierarchical? • Mass hierarchy:Normal or inverted?In addition: Hierarchy is good model discriminator! Better mass bounds from cosmology, 0nbb-decay Adiabatic conversion in SN PD General Meeting - Walter Winter

  5. Neutrino oscillations with two flavors Mixing and mass squared difference:na “disappearance”:nb “appearance”: ~Frequency Amplitude Baseline: Source - Detector Energy PD General Meeting - Walter Winter

  6. Picture of three-flavor oscillations Atmosphericoscillation:Amplitude: q23Frequency: Dm312 Solaroscillation:Amplitude: q12Frequency: Dm212 Sub-leading effect: dCP Coupling strength: q13 Magnitude of q13is key to “subleading” effects: • Mass hierarchy determination • CP violation nm ne flavor transitions in atmospheric oscillations (“Oscillation maximum”) PD General Meeting - Walter Winter

  7. Some “man-made” neutrino sources For leading atm. params Signal prop. sin22q13 Contamination PD General Meeting - Walter Winter

  8. Disappearance measurements • Use expansions in small parameters: • Short baseline reactor experiments: 2nd term small for sin22q13 >> 10-3! • Long baseline accelerator experiments: No dCP, No mass hierarchy! (see e.g. Akhmedov et al., hep-ph/0402175) PD General Meeting - Walter Winter

  9. Appearance channels: nmne • Complicated, but all interesting information there: q13, dCP, mass hierarchy (via A) (Cervera et al. 2000; Freund, Huber, Lindner, 2000; Freund, 2001) PD General Meeting - Walter Winter

  10. Existing experiments: Future experiments: Input parameters Data Simulated data Fit parameters to data:Precision of quantity of interest Fit parameters to data:Precision of quantity of interest Predictions for future experiments ? Simulation of future experiments = “Hypothesis testing” PD General Meeting - Walter Winter

  11. Determine the precision of the quantity of interest “Unused” parameteres are usually marginalized over (projection onto axis/plane of interest) Source of correlations! Represent the values implemented by nature Known within current limits Change the event rates, top. Have to be interpreted like“If the value of … is …, then the performance will be …” - Luck or not luck? Used for risk minimization! Simulated versus fit parameters Fit parameters Simulated/true params PD General Meeting - Walter Winter

  12. q13 exclusion limit (1) • Describes the new q13 limit for the hyopthesis of no signal (q13=0) • Define as largest fit value of q13=0, which fits true q13=0 • Straightfoward inclusion of correlations and degeneracies • Does not depend on the simulated dCPand mass hierarchy! (Huber et al hep-ph/0403068) PD General Meeting - Walter Winter

  13. Simulated parameters:q13=0, dCP meaningless Relatively “simple” parameter dependencies No dependence on dCP, mass hierarchy Fit parameters:All six parameters Correlations and degeneracies affect this performance indicator Small for NOvA etc.;Rate ~ 0 q13 exclusion limit (2) Look for any combination of parameters which “fake” the smallest rate PD General Meeting - Walter Winter

  14. Simulated parameters:Hypothesis:Certain q13, dCP, mass hierarchy Can we find a signal for this hypothesis? Maximize parameter space for discovery Fit parameters:Relatively simple as long as “solar term” negligible Small impact of correlations Small for NOvA etc.;Rate ~ 0 q13 discovery limit Simulated rate depends on all parameters PD General Meeting - Walter Winter

  15. q13 exclusion vs. q13 discovery • Two different performance indicators • q13 exclusion interesting for pre-PD era:What will be the limits at PD startup? How far can we go for sure = can we exclude that we will not discover q13? • q13 discovery interesting for PD era:In what cases could we discover something? • Completely risk-minimized discovery potential corresponds approximately to q13 exclusion limit • Discovery limit has to be interpreted with care! • Correlations and degeneracies in one case translate into dependence on dCP and mass hierarchy in the other PD General Meeting - Walter Winter

  16. q13 exclusion limit at PD startup • q13 may or may not have been discovered at PD startup: Need substantially more thanexisting beamline + detectorBut: superbeams way to go Conceptual casesin PD study Probably need neutrino factory Could work on CP violation+mass hierarchywith existing beamline + det. NUE=“NuMI Up-graded Experiment” ~ NOvA Scenario 3:Discovery unlikely until PD startup Scenario 1:Certainly discovereduntil PD startup Scenario 2:Discovery likely before PD startup PD General Meeting - Walter Winter

  17. q13 discovery and CP fraction plots Read: For sin22q13=0.04, we expect a discovery for 20% of all values of dCP Sensitive region as function of true q13 and dCP New primer in PD-NOD! Fraction of dCP for successful discovery dCP values now stacked for each q13 PD General Meeting - Walter Winter

  18. “Fraction of dCP”= Measure for luck? No luck needed; works for all d, hier. • Discovery potential depends on true dCP, mass hierarchy • For uniform distribution in dCP:Fraction of dCP = Probability to discoverdCP • Remember: dCP comes from a complex phase factor eid in the mixing matrix Thus: a distribution in sin d would be theoretically “unnatural” “Typical” d;50-50 chance Best case d, hierarchy (FNAL Proton Driver study, to appear in 2005) PD General Meeting - Walter Winter

  19. Discovery limit landscapes: q13 • Assume that each experiment runs five years (most in neutrino mode only) • Characterize dependence on dCP as bands reflecting all possible chases • Choose starting times as close as possible to values in respective LOIs/proposals • Include statistics+systematics+correlations • Assume that disappearance channels give best information on leading atmospheric params PD General Meeting - Walter Winter

  20. Evolution of q13 discovery limit Proton driver + NUE(NuMI Upgraded Experiment): Pass branching point almost for sure Superbeamshave a better discovery potential than reactor exps for a large number of CP values! Branching point between Scenarios 2 and 3 (not for PD!) MINOS and CNGSHave approximately equal performance(depends somewhat onassumptions) Reactor experiments:No dependence on dCP! Reactor-IIcorresponds to “large” reactor experiment(Braidwood or similar). Actual performance depends on control of systematics! Based on T2HK;assume start 10 years after T2K starts Starts about 10 years after branching point;changes polarity after 2.5 years (normal mass hierarchy assumed) PD General Meeting - Walter Winter

  21. Evolution of q13 discovery limit • Obviously different generations of experiments • New generation will quickly determine potential • Reactor experiments provide complementary information! • Antineutrino running could help for risk minimization • For inverted hierarchy: Beam limits shift somewhat down! (from: FNAL Proton Driver Study, to appear in 2005) PD General Meeting - Walter Winter

  22. Examples for q13 cases (1) ~2012-2013: q13 signal likely at superbeams or reactor experiments • Assume: Actual value of sin22q13 = 0.03 PD+NUE+2nd NUE very competitiveFast+cost efficient alternative to T2HK!? (from: FNAL Proton Driver Study, to appear in 2005) PD General Meeting - Walter Winter

  23. Examples for q13 cases (2) Discovery of q13 unlikely without PD and impossible for T2K If no PD at Fermilab, probably no further superbeam program! • Assume: Actual value of sin22q13 = 0.007 But: One could have done almost of all the physics with a superbeam program! (from: FNAL Proton Driver Study, to appear in 2005) PD General Meeting - Walter Winter

  24. Summary • NUE discovery potential for q13 greatly increased by Proton Driver • NUE and NUE+PD have “very likely” better q13 discovery potential then reactor experiments • Predictions for reactor experiments more robust: Do not depend on dCP and mass hierarchyThus: Very competitive exclusion limits expected (if no signal) • Dependence of Pme on dCP and mass hierarchy implies that genuine potential of PD-based experiments in these quantities PD General Meeting - Walter Winter

  25. Special topic: Why does worst-case limit hardly improve for superbeam upgrades? • Assume oscillation maximum, neglect solar term • Then for one specific value of dCP (typically p/2): • This means: For sin2q13 ~ a (or sin22q13 ~ a2 ~ 0.001) Pme is very small independent of the total number of events • Therefore: The closer the experiment performance to sin22q13 = 0.001, the broader the band and the more unaffected the lower end of the band (equivalent to good performance in dCP!) PD General Meeting - Walter Winter

More Related