Neutrino factory physics reach … and impact of detector performance 2 nd ISS Meeting KEK, Tsukuba, Japan January 24, 2006 Walter Winter Institute for Advanced Study, Princeton

Jan. 24, 2006ISS KEK NuFact - Walter Winter2 Contents Introduction Introduction Optimization of a neutrino factory: Optimization of a neutrino factory: –Muon energy and baseline –Disappearance channel optimization –Impact of detector performance Physics beyond the “big three” indicators: (  13 discovery, CP violation, mass hierarchy) Physics beyond the “big three” indicators: (  13 discovery, CP violation, mass hierarchy) –  13 and  CP precision measurements –Physics case for  13 =0? –New physics tests –Geophysics with a neutrino factory? Summary Summary

Jan. 24, 2006ISS KEK NuFact - Walter Winter3 Appearance channels:  e  Complicated, but all interesting information there:  13,  CP, mass hierarchy (via A) (Cervera et al. 2000; Freund, Huber, Lindner, 2000; Freund, 2001)

Jan. 24, 2006ISS KEK NuFact - Walter Winter4 Correlations and degeneracies Connected (green) or disconnected (yellow) degenerate solutions (at a chosen CL) in parameter space Connected (green) or disconnected (yellow) degenerate solutions (at a chosen CL) in parameter space Affect performance of appearance measurements. For example,  13 sensitivity Affect performance of appearance measurements. For example,  13 sensitivity (Huber, Lindner, Winter, 2002) Discrete degeneracies: (also: Barger, Marfatia, Whisnant, 2001) Intrinsic ( ,  13 )-degeneracy (Burguet-Castell et al, 2001) sgn-degeneracy (Minakata, Nunokawa, 2001) (  23,  /2-  23 )-degeneracy (Fogli, Lisi, 1996) Discrete degeneracies: (also: Barger, Marfatia, Whisnant, 2001) Intrinsic ( ,  13 )-degeneracy (Burguet-Castell et al, 2001) sgn-degeneracy (Minakata, Nunokawa, 2001) (  23,  /2-  23 )-degeneracy (Fogli, Lisi, 1996)

Jan. 24, 2006ISS KEK NuFact - Walter Winter5 NF-Strategies to resolve degeneracies … depend on sin 2 2  13 ! Combine with superbeam upgrade ( sin 2 2  13 > ) (Burguet-Castell et al, 2002) Combine with superbeam upgrade ( sin 2 2  13 > ) (Burguet-Castell et al, 2002) Combine with “silver channels” e ->  ( sin 2 2  13 > ?) (Donini, Meloni, Migliozzi, 2002; Autiero et al, 2004) Combine with “silver channels” e ->  ( sin 2 2  13 > ?) (Donini, Meloni, Migliozzi, 2002; Autiero et al, 2004) Better detectors: Higher energy resolution, higher efficiencies at low energies (CID!) ( sin 2 2  13 > ?) (Later this talk) Better detectors: Higher energy resolution, higher efficiencies at low energies (CID!) ( sin 2 2  13 > ?) (Later this talk) Second NF baseline: “Magic baseline” ( sin 2 2  13 > ) (Lipari, 2000; Burguet-Castell et al, 2001; Barger, Mafatia, Whisnant, 2002; Huber, Winter, 2003; others) Second NF baseline: “Magic baseline” ( sin 2 2  13 > ) (Lipari, 2000; Burguet-Castell et al, 2001; Barger, Mafatia, Whisnant, 2002; Huber, Winter, 2003; others) Other possibilities? Other possibilities? (Fig. from Huber, Lindner, Winter, 2002) Intrinsic degeneracy disappears for better energy threshold! sin 2 2  13 =0.001

Jan. 24, 2006ISS KEK NuFact - Walter Winter6 Example: “Magic baseline” Idea: Yellow term = 0 independent of E, oscillation parameters (Huber, Winter, 2003) Idea: Yellow term = 0 independent of E, oscillation parameters (Huber, Winter, 2003) Purpose: “Clean” measurement of  13 and mass hierarchy Purpose: “Clean” measurement of  13 and mass hierarchy Drawback: No  CP measurement at magic baseline Drawback: No  CP measurement at magic baseline  combine with shorter baseline, such as L=3 000 km  13 -range: < sin 2 2  13 < 10 -2, where most problems with degeneracies are present  13 -range: < sin 2 2  13 < 10 -2, where most problems with degeneracies are present

Optimization of a neutrino factory First time GLoBES is run on a parallel cluster! 4 yr x  + decays + 4 yr  - decays Detector: 50 kt magnetized iron calorimeter ISS-values? 100 kt, 5+5 years running time = factor 2.36 luminosity increase for useful decays/year

Jan. 24, 2006ISS KEK NuFact - Walter Winter8 Muon energy and baseline:  13 Example:  13 sensitivity relative to minimum in each plot (3  ) Example:  13 sensitivity relative to minimum in each plot (3  ) Important result: Since muon energy ~ $ 40 GeV enough?! Important result: Since muon energy ~ $ 40 GeV enough?! Threshold effects: Threshold effects: (Huber, Lindner, Rolinec, Winter, to appear; also: Freund, Huber, Lindner, 2001)

Jan. 24, 2006ISS KEK NuFact - Walter Winter9 Muon energy and baseline: CP violation Degeneracy problem for  CP =3  /2 not solvable without additional information or improvements Degeneracy problem for  CP =3  /2 not solvable without additional information or improvements Example: Sensitivity to max. CP violation (absolute “conservative” reach, 3  ) Example: Sensitivity to max. CP violation (absolute “conservative” reach, 3  ) (Huber, Lindner, Rolinec, Winter, to appear)

Jan. 24, 2006ISS KEK NuFact - Walter Winter10 Muon energy and baseline: Mass hierarchy Example: Sensitivity to normal hierarchy (absolute reach, 3  ) Example: Sensitivity to normal hierarchy (absolute reach, 3  ) (Huber, Lindner, Rolinec, Winter, to appear) If sin 2 2  13 small: Very long baseline necessary! If sin 2 2  13 small: Very long baseline necessary!

Jan. 24, 2006ISS KEK NuFact - Walter Winter11 Disappearance channel Disappearance information important to reduce errors on leading parameters Disappearance information important to reduce errors on leading parameters (see e.g. Donini, Fernandez-Martinez, Rigolin, 2005; Donini, Fernandez-Martinez, Meloni, Rigolin, 2005) Idea: Use data sample without charge identification for disappearance, i.e., add right and wrong sign muon events Idea: Use data sample without charge identification for disappearance, i.e., add right and wrong sign muon events  Better eff. at low E! (de Gouvea, Winter, 2005; Fig. from Huber, Lindner, Rolinec, Winter, to appear) sin 2 2  13 = 0 (Fig. from Huber, Lindner, Winter, 2002) sin 2 2  13 precision

Jan. 24, 2006ISS KEK NuFact - Walter Winter12 Better detector? Hybrid detector? Better energy resolution? Was: 0.15 x E (approximation) Optimistic: ? Better energy resolution? Was: 0.15 x E (approximation) Optimistic: ? Lower appearance threshold? Was: 4 GeV, linearly climbing to maximum at 20 GeV Optimistic: Max. already at 1 GeV Lower appearance threshold? Was: 4 GeV, linearly climbing to maximum at 20 GeV Optimistic: Max. already at 1 GeV CC/NC Backgrounds: Assume power low such that ~ 5 x each at mean energies CC/NC Backgrounds: Assume power low such that ~ 5 x each at mean energies  Background increases at low energies  Even if CID improved, NC background limits performance! (Fig. from Huber, Lindner, Winter, 2002; Gray curve from Cervera et al, 2000) (Cervera et al, 2000)

Jan. 24, 2006ISS KEK NuFact - Walter Winter13 Better detector: 4 toy scenarios 1. “Standard” Appearance with “standard” threshold climbing from 4 to 20 GeV Appearance with “standard” threshold climbing from 4 to 20 GeV 15% E energy resolution 15% E energy resolution Disappearance without CID Disappearance without CID Background constant in E Background constant in E 2. “Optimal appearance” Appearance with better threshold + better Eres Appearance with better threshold + better Eres Disappearance with CID !!! (old) Disappearance with CID !!! (old) Better background modeling Better background modeling 3. “Better Eres” Like 2, but “old” threshold Like 2, but “old” threshold 4. “Better threshold” Like 2, but “old” Eres modeled as 0.5 Sqrt(E) Like 2, but “old” Eres modeled as 0.5 Sqrt(E)

Jan. 24, 2006ISS KEK NuFact - Walter Winter14 Better detector:  13 sensitivity High CL chosen (4  ): avoid threshold effects (  13,  CP )-degeneracy affects sensitivity limit at L ~ km High CL chosen (4  ): avoid threshold effects (  13,  CP )-degeneracy affects sensitivity limit at L ~ km Better detector threshold: L= km most attractive  13 -baseline Better detector threshold: L= km most attractive  13 -baseline “Magic baseline”

Jan. 24, 2006ISS KEK NuFact - Walter Winter15 Better detector: MH,  CP Choose  CP =3  /2 because most problems with degeneracies around there: Cannot be completely resolved! Both Eres and threshold increase sensitive region; Especially: better threshold

Jan. 24, 2006ISS KEK NuFact - Walter Winter16 Better detector: Large  13 Both better Eres and threshold useful Both better Eres and threshold useful Both better detector and smaller matter density uncertainty useful Both better detector and smaller matter density uncertainty useful Either or combination sufficient to compete with the superbeam upgrades (prel.) Either or combination sufficient to compete with the superbeam upgrades (prel.) Large  +better detector prefers shorter baselines ( km); E  small OK Large  +better detector prefers shorter baselines ( km); E  small OK No  CP at L magic !

Jan. 24, 2006ISS KEK NuFact - Walter Winter17 Better detector: Summary Better threshold helps for Better threshold helps for –Optimization: »3000 km competitive for  13 (compared to 7500 km) But: depends on chosen CL and finally achieved luminosity »Lower E  possible (not shown); 30 GeV muons? –Better absolute reaches (MH,  CP ) Better energy resolution helps for Better energy resolution helps for –Leading parameter measurements (very preliminary) –Indirectly for sub-leading parameters –Somewhat better absolute reaches (MH,  CP ) However: Even optimal detector cannot resolve degeneracies completely! However: Even optimal detector cannot resolve degeneracies completely!

Physics beyond the “big three” indicators (  13 discovery, CP violation, mass hierarchy)

Jan. 24, 2006ISS KEK NuFact - Walter Winter19 Precision of  13 How precisely can one measure  13 if found? How precisely can one measure  13 if found? Dependence on  CP characterized by bands: Dependence on  CP characterized by bands: Qualitatively similar behavior to  CP precision Qualitatively similar behavior to  CP precision (Fig. from Huber, Lindner, Winter, 2002)

Jan. 24, 2006ISS KEK NuFact - Walter Winter20 Precision of  CP / CP coverage Define: CP coverage = Fraction of all fit values of  which fit a chosen true  CP coverage <= 360 o Define: CP coverage = Fraction of all fit values of  which fit a chosen true  CP coverage <= 360 o CP scalingCP pattern  2 = 9, 4, 1; dashed: no degs) (Fig. from Huber, Lindner, Winter, hep-ph/ ) True values of  and  13 affect topology! Degeneracies! True values of  and  13 affect topology! Degeneracies! But: Degeneracies not everywhere in param. space important But: Degeneracies not everywhere in param. space important Degeneracy problem even bigger than for max. CP violation!

Jan. 24, 2006ISS KEK NuFact - Walter Winter21 CP coverage and “real synergies” km km versus all detector mass at km (2L) km km versus all detector mass at km (2L) Magic baseline allows a risk-minimized measurement (unknown  ) Magic baseline allows a risk-minimized measurement (unknown  ) “Staged neutrino factory”: Option to add magic baseline later if in “bad” quadrants? “Staged neutrino factory”: Option to add magic baseline later if in “bad” quadrants? Any “extra” gain beyond a simple addition of statistics One baseline enough Two baselines necessary (Huber, Lindner, Winter, 2004)

Jan. 24, 2006ISS KEK NuFact - Walter Winter22 Physics case for  13 =0? Establish MSW effect for  13 =0 by solar oscillation (appearance prob.) L > 5,500 km (Winter, 2004) Determine mass hierarchy for  13 =0 (disappearance probability) L ~ 6,000 km (de Gouvea, Jenkins, Kayser, 2005; de Gouvea, Winter,2005) Very long (>> 3,000 km) baseline important component of any such program! In addition:  13 =0 would be an important indicator for some symmetry!

Jan. 24, 2006ISS KEK NuFact - Walter Winter23 New physics tests Test unitarity and small ad-mixtures of “new physics” by:   detection P ee +P e  +P e  = 1? (Donini, Meloni, Migliozzi, 2002; Autiero et al, 2004)  Neutral currents (hard) (Barger, Geer, Whisnant, 2004)  Spectral signature on probability level Example: Damping effects (Blennow, Ohlsson, Winter, hep-ph/ )  More complicated: Hamiltonian-level effects (e.g., Blennow, Ohlsson, Winter, hep-ph/ ) Example: Oscillation-NSI confusion theorem (Huber, Schwetz, Valle, 2002) See other talks in this workshop for specific possible effects! E.g. Hisano, Kanemura, Sato, Sorel, Xing

Jan. 24, 2006ISS KEK NuFact - Walter Winter24 Other physics: Geophysics? Example: Measure inner core density  IC Per cent level precision not unrealistic Per cent level precision not unrealistic Survives unknown oscillation parameters Survives unknown oscillation parameters More recent discussions: Discriminate seismically degenerate geophysics models in mantle, test plum hypothesis etc.? More recent discussions: Discriminate seismically degenerate geophysics models in mantle, test plum hypothesis etc.? (Winter, 2005) BNL CERN JHF Inner core shadow sin 2 2  13 =0.01

Jan. 24, 2006ISS KEK NuFact - Walter Winter25 Summary and conclusions Energy and baseline optimization: Muon energy of 40 GeV enough!? L=1000 km, E  =20 GeV not an option!? Energy and baseline optimization: Muon energy of 40 GeV enough!? L=1000 km, E  =20 GeV not an option!? Better detector will definitively help Especially: Better threshold (app. low energy efficiency) Better detector will definitively help Especially: Better threshold (app. low energy efficiency) There is plenty of “beautiful” neutrino oscillation physics beyond “standard”  13, mass hierarchy, CP violation. Example: Physics case  13 =0 There is plenty of “beautiful” neutrino oscillation physics beyond “standard”  13, mass hierarchy, CP violation. Example: Physics case  13 =0 Problem for any “serious” calculation: calculation time! So far calculated on opportunistic systems with greatly variable calculation time! Parallel cluster time needed! Example: One L-E-Plot takes ~ CPU hours Problem for any “serious” calculation: calculation time! So far calculated on opportunistic systems with greatly variable calculation time! Parallel cluster time needed! Example: One L-E-Plot takes ~ CPU hours Next steps: Channel requirements, … Next steps: Channel requirements, …

Jan. 24, 2006ISS KEK NuFact - Walter Winter26 Better detector in L-E-space:  13 sens. 3  sensitivity to sin 2 2  13 3  sensitivity to sin 2 2  13 Better EresBetter thresholdBetter Eres+thresh. (Huber, Lindner, Rolinec, Winter, to appear)

Jan. 24, 2006ISS KEK NuFact - Walter Winter27 Better detector in L-E-space: Large  13 CP fraction for CP violation (3  “Standard” “Optimal appearance” L=1000 km/E  =20 GeV possible alternative? CP fraction for CP violation (3  “Standard” “Optimal appearance” L=1000 km/E  =20 GeV possible alternative? (Huber, Lindner, Rolinec, Winter, to appear)