Measuring -mixing parameters at -telescopes Pasquale Dario Serpico MPI für Physik - Munich based on hep-ph/ , to appear in PRL, in collaboration with M. Kachelrie ß Current Topics in Astroparticle Physics, April 2005 – Ringberg Castle

Overview of the Talk An interesting Galactic Anisotropy in CR: neutron source(s)? A promising point-like target for -telescopes A chance for galactic  -beams Discussion & Conclusions P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle -telescopes and -mixing: a (brief) overview

-telescopes and -mixing -telescopes and -mixing 1. The signature and efficiency of these detectors depend on the flavour! In particular, oscillations may “rescue” signals 2.In some cases, -mixing angles might be studied at -telescopes Only standard physics considered here, otherwise many other interesting possibilities would open! P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

Flavour Discrimination e + N → e + X e + N → e + X  + N →  + X  + N →  + X  + N →  + X  + N →  + X E > GeV E > 1 TeV E > few PeV <1 o O(25 o ) Simplified picture! Subleading flavour-independent effects (NC showers), “fake signals” (e.g.  events tracks in  →  events) P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

A “rescued” signal: the Galactic diffuse A “rescued” signal: the Galactic diffuse  P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle Independent confirmation of the (large) mixing in the  sector. Event rate of O(1 yr -1 sr -1 ) for two separable and contained showers with E ≈ PeV in a Km 3 -telescope H. Athar et al. APP 18 (2003) 581 The pp -flux from CR hitting Galactic diffuse matter develops a large oscillated  -component. Atmospheric background is softer due to relevant energy losses of mesons. Moreover, it is  -suppressed: at E ≈ TeV-PeV the oscillation length is too large (mainly prompt  !)

-telescopes, the Glashow resonance and   -telescopes, the Glashow resonance and   Unique to e, and  enhanced at E ≈ 6.3 PeV P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle Standard astrophysical sources produce and via pp →  X, p  →  X. Both give flavour ratios at production  e :      ≈ ⅓ : ⅔ :0, but p  mainly gives e (via  + ), while pp almost equally e and e  - The measurable ratio R GR ≡ e GR      CC is thus sensitive to mixing angles (mainly to   ) as well as to the nature of the astrophysical source (% of pp “contamination” ≡  ). For   =0 o and   =45 o  Bhattacharjee & Gupta [astro-ph/ ] get R GR ≈ 15[Sin 2 2  12 +  (1-0.5 Sin 2 2  12 )] e  e - →  W - → anything “Glashow Resonance”

-telescopes, the Glashow resonance and   -II -telescopes, the Glashow resonance and   -II P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle   =40 o   =45 o   =0 o   =45 o   =32.5 o   =15 o   =0 o   =45 o   =32.5 o   =15 o   =0 o   =45 o   =9 o   =0 o Bhattacharjee & Gupta [astro-ph/ ]

An interesting Galactic Anisotropy in CR: neutron source(s)?

A Galactic Plane excess in Cosmic Rays AGASA reported a 4% excess in HECR around eV (1 EeV) from a couple of hot-spots in the galactic disk Confirmed also by SUGAR and Fly’s Eye: a rare case of concordance in a field where experiments often disagree each other! P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

The birth of Galactic neutron Astronomy? Neutrons are natural candidates to explain the signal no GMF bending (huge for p too!) Signal Energy-range ≈ boosted n-lifetime on galactic scales c  n ≈ 10 kpc (E n / EeV) P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

The associated -flux: a promising point-like target for -telescopes

If n explain the excess, a garanteed flux is the one below PeV from n-decay E / E n ~ Q / m n ~ 0.8 x → E ~ PeV, for E n ~ EeV The energy-window accessible to “conventional” -telescopes is from ~ 100 GeV up to ~ eV ( PeV). From Neutrons to Neutrinos Can we observe them? Conservative! Lower energy n undetectable in CR (decay & GMF bending) Further ‘s from decay of associated meson decay (to be discussed at the end) P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

Detectability in IceCube L. Anchordoqui, H. Goldberg, F. Halzen & T.J. Weiler PLB 593 (2004) 42 Normalizing to the CR anisotropy, ~ 20 events per year from Cygnus region in IceCube (under construction at the South pole) In a few years, IceCube will attain discovery sensitivity for n → e →  !!! Standard oscillation phenomenology implies ≈ 4  /yr tracks in 0.7 o circle (Atm. background is~2.3  /yr) ≈ 16 e    showers/yr in 25 o, cone, due to poor resolution. (Atm. background fluctuation is~12 showers/yr) P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

A chance for galactic  -beams

Mixing Mixing Mixing Matrix U Atmospheric/K2K 35.7 o    54.3 o Solar/Kamland 28.7 o    37.5 o CHOOZ+Others    12.5 o  CP  s lk ≡ Sin  lk, c lk ≡ Cos  lk From a pure (anti-) e flux, the probability P e  to observe the flavour  at a distance much larger than the oscillation lengths (as for galactic scales, E≈ TeV and the actual values of  m 2 ’s) is Present experiments give at 3  [ Maltoni et al., NJP 6 (2004) 122] P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

Sensitivity to mixing angles-I The peculiar state in flavour space at source (  e :      1:0:0) allows to perform a combined disappearence experiment (of e ) appearence experiment (  and  ) that is sensitive to mixing angles via the observable ratio of tracks to showers    e    In particular, what is the sensitivity of such a signal to the unknown parameters   and  CP ? Chance for “Galactic  -beams”! R= P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

Sensitivity to mixing angles - II For   =  /3 and   =  /2 one has Though in the following we will use the exact formulae, they show some key-features of the signal. P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

Sensitivity to  13 (and  23 ) For best fit   =32.5 o and in the best case  CP =  one has a variation of order 30-50% in 0 o <   < 10 o, depending on  . In the most likely case   =45 o, the flux ratio differs up to a factor 2 with respect to the expected flavor ratio of generic astrophysical sources, R=0.5 P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle Note the octant dependence!

Sensitivity to  CP For experimental best fit   =32.5 o and   =45 o, the flux ratio has a maximal variation of about 30% and differs up to a factor 2 with respect to the expected flavor ratio of generic astrophysical sources P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

Discussion: models,  -background

Discussion: Nuclei & Pions… The usually discussed astrophysical sources are based on pp →  X, p  →  X. After oscillations → flavour ratio 1:1:1 insensitive to   and  CP !!! One has to check that Neutrons from Nuclei at EeV in (some) Galactic sites are expected Viable models can be built compatible with observations and constraints It is experimentally possible to disprove the A → n → scenario Is it possible/realistic to neglect from these channels? P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

Neutrons (and ) from Nuclei? Within a factor of a few, E ≈ O(1 EeV) is the transition region between the Heavy-nuclei end of the Galactic Spectrum and the proton-dominated Extragalactic contribution. Recent CR data support this scenario Dova et al. APP 21 (2004) 597 At E ≈ EeV, few galactic sources match the right acceleration requirments, and the GMF hardly confines cosmic rays. Higher charged particles are easily accelerated and confined. Conceivable that the n from nuclei dissociations in matter and  fields in (a few) galactic accelerators may become visible. Favored regions are the Nuclear Bulge and dense clouds of higher B-field intensity… P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

Discussion: Nuclei & Pions… The usually discussed astrophysical sources are based on pp →  X, p  →  X. After oscillations → flavour ratio 1:1:1 insensitive to   and  CP !!! One has to check that Neutrons from Nuclei at EeV in (some) Galactic sites are expected Viable models can be built compatible with observations and constraints It is experimentally possible to disprove the A → n → scenario Is it possible/realistic to neglect from these channels? P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

What’s the expected “contamination”? Viable models of the A → n → scenario exist, e.g.: Cygnus region: L. Anchordoqui et al. PLB 593 (2004) 42 SGR A East SN remnant: Grasso and Maccione [astro-ph/ ] Within the expected statistical accuracy of IceCube & at the same subleading level of other effects neglected in our first estimate (NC role, tracks from  →  events, etc.) From astrophysical data e.g. on the Cygnus region (e.g. UV  density) and hadronic physics data (e.g. secondary population yields in hadronic interactions) an effective volume for nuclear dissociation 27 times larger than for hadronic interactions has been estimated. In this case, likely  contaminations to flux are at the O(10%) level →  R ≈ only! P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

What’s the expected “contamination”? - II P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle Extreme pp, assuming E p max = ∞ Lower limit to n from nuclei: Only He contribution, metallicity at solar level (SGR A East is known for a high metallicity, ≈ 4 solar ) Only single nucleon stripping Only effects of IR background Again, reasonable to expect a nuclear contribution to n much larger than the one from pp D. Grasso and L. Maccione [astro-ph/ ] Observable n at Earth, normalized to HESS  data n-decay suppressionBehaviour due to  and CR 

Discussion: Nuclei & Pions… The usually discussed astrophysical sources are based on pp →  X, p  →  X. After oscillations → flavour ratio 1:1:1 insensitive to   and  CP !!! One has to check that Neutrons from Nuclei at EeV in (some) Galactic sites are expected Viable models can be built compatible with observations and constraints It is experimentally possible to disprove the A → n → scenario Is it possible/realistic to neglect from these channels? P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

Is the Scenario Falsifiable? Provided that the “n-chain” explains the anisotropy,  fluxes (from n-decay alone!) are easily observable in IceCube, with a detailed measurement in a decade. (normalized to CR data, not a model !!!) If the  chain dominates, the flux should be much higher (factor>100!) though with a flavour ratio of about 1:1:1 Possible discovery already in AMANDA-II High flux and R=0.5 would disprove the dominance of A → n → Also  -rays constraints! P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

Overview If the CR anisotropy around the EeV is confirmed to be of neutronic origin, a likely possibility is that in a next generation -telescope like IceCube it provides a measurement sensitive to  13 and  CP Both improved CR data (AUGER, KASCADE-Grande) and direct measurement of -flux (AMANDA, IceCube, Mediterranean Telescopes) can falsify the proposed mechanism, thus making feasible in forthcoming years to assess the effective viability of the method P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

Conclusions On Earth, the hunting for  13 and  CP is open. Terrestrial beta-beam facilities have been proposed, of O(1) G€ cost, with the main issue in the beam preparation As for the Solar neutrino problem, the Heavens might still be helpful to  physicists! The scenario discussed here shows that it is conceivable that Nature might provide  -beams “for free”, that could be studied at -telescopes already in construction. -telescopes are optimized for astrophysical purposes, but they may have a potential for -mixing physics, too. P. D. Serpico, MPI für Physik - Munich “ Measuring -mixing parameters at -telescopes” CuTAPP ‘05, Ringberg Castle

LEOFEST 2005 I wish you’ll remain forever young…. Happy Birthday!!!