The Future of ν Physics

Transcription

1 The Ftre of ν Physics Jorge G. Morfín Fermilab

2 We are srronded by Netrinos Over ν from the sn passing throgh each of s every second. Over 10 3 ν from cosmic ray interactions in the atmosphere passing throgh s every second. ν s are literally all over the place. We have experimented with them for over 30 years. Perhaps it wold be nice to know jst a little bit more abot them... sch as do they have mass?

3 Why do we care if they have mass? If netrinos have even a small mass then it is sign for NEW PHYSICS beyond the Standard Model of weak/electromagnetic interactions. Since there are so many netrinos throghot the niverse, even a small mass makes the netrino a heavyweight in the mass density of the niverse! Are there any hints that we might be dealing with massive netrinos?

4 Hints that ν might have a (small) mass! There is a deficit of ν e coming from the sn - verified by many experiments. (SperK: Obs/Expt =.47±.06) There are missing ν µ coming from cosmic ray interactions in the pper atmosphere, again verified by many experiments (SperK: R data/mc =.67±.02±.05) The LSND experiment has fond evidence - yet to be verified - for ν µ --> ν e.

5 What s going on here?? One possibility is that ν l is oscillating into ν l Difference between: flavor states; ν l interacts with matter it yields a charged lepton of flavor l and Mass states; ν l need not be a mass eigenstate bt rather a sperposition of mass eigenstates, at least 3 mass eigenstates and perhaps more. ν = U ν l lm m m

6 What are netrino oscillations? The U lm are known as the leptonic mixing matrix U. If ν l is a sperposition of several mass states with differing masses which case them to propagate differently, we have netrino oscillations. The amplitde for the transformation ν l --> ν l is: A( ν ν ) = A( ν is ν ) A( ν propagates)a( ν is ν ) l ' l l m m m l' A( propagates) = exp -i M 2 L m νm 2 E

7 Example of Two Flavor Oscillations If there are only two flavors involved in the oscillations then the U matrix takes on the following form and the probability (sqare of the amplitde) can be expressed as: iδ cosθ e sinθ U = and -iδ e sinθ cosθ P( νl ν ' ) = sin 2θsin. m ( ) l 1 27 ev 2 2 with m M - M L( km) E( GeV)

8 Crrent Sm of all Experimental Reslts

9 What abot 3 (or more) netrinos Natrally, life is more complicated, bt the principle is the same and we get the bons of CP violations as in the qark sector P(ν µ --> ν e ) P(ν µ --> ν e ). The components of U now involve θ 13, θ 23,θ 12 and δ and the probabilities involve m 13, m 23 and m 12. Standard Theorists Scenario: m 2 23 >> m 2 12 ν e ν µ ν τ U ν ν 2 1 ν 3 Prodce Weak Eigenstate... Detect Weak Eigenstate... Propage Mass Eigenstate

10 In the Next 10 years. LSND will be checked by MiniBooNe: Sterile ν s? SNO, Borexino and Kamland will stdy the solar netrino deficit: Know whether SMA or LMA is preferred. Gives s m 2 12 and θ 12 The Atmospheric Anomaly will be examined by accelerator experiments K2K and MINOS: m 2 23 to 10-15% and θ 23 to 10%. Ta appearance experiments at CNGS?

11 Remaining Qestions: How to Answer Them. Is θ 13 non-zero? What is the mass hierarchy? Is there CP violation? Are there sterile netrinos? What do we need to answer them? Appearance Measrements. Have to Exploit Matter Effects. Have to go to > 1000 km baseline. Need to see ν e in the initial or final state. Separate ν a and ν a beams. Best to have two a real mix of ν µ and ν e beams.

12 c c The Netrino Factory Design already exists for a 20 GeV Storage Ring with 6 x 1019 m decays per year. Active working grops pshing the design with R&D projects in the U.S., Erope and Japan. Proton Driver + Target Station 50 m long drift Linac 100 m long Indct. Linac 60 m long bnching 140 m long cooling 1.6 GeV, 200 MHz linac >3.4 GeV linac 3 GeV of acceleration 8-16 GeV RLA2, 8 GeV max, 7.5 MeV /m average Accel. Fr. = 200 MHz Trns = 4 r = 30 m, C~600 Arc = 180 m Matching = 200 m (beam separators /combiner) Linac = 2 x 150 m RLA2, 39 GeV max, 7.5 MeV /m average Acc. Freq = 400 MHz Trns = 5 r = 60 m, C~2500 m Arc = 380 m Matching = 600 m (beam separators/ combiner) Linac = 2 x 600 m 300 m 600 m 900 m 1200 m Storage ring, 50 GeV max, Trns = 180 ( =1/ e) r = 50 m, C~1800 m Arc = 150 m Matching = 100 m Prodction Straight West 1500 m 1800 m

13 Netrino Factory: Event Energy and Radial Distribtion 10, 25 and 50 GeV Mons

14 What abot LONG Baselines?

15 The Importance of Matter Effects! When a netrino propagates throgh matter, rather than vacm, its oscillation probability can be greatly enhanced! Comes from coherent elastic scattering which is for ν e only. These effects can determine the SIGN of a mass difference. Need L > 1000 km to see this. Need ENORMOUS detectors! ν e e- - ν e e- - e + W ν e Coherent Elastic - Scattering: only! ν e - e ν e - W ν e

16 Near and Far Ftre ν Osc. Detectors Magnetized Steel / Scintillator - MINOS Liqid Ar TPC + Spectrometer - ICANOE/ICARUS H2O Cerenkov + Spectrometer - SperK Emlsion Detector - OPERA Can any/all of these detectors help reach or goals? Is θ 13 non-zero? What is the mass hierarchy? Is there CP violation? Are there sterile netrinos?

17 Wait there s a lot more physics to go.. Near Detector Physics GeV µ decays in the straight section yields 4.5 x 10 6 events/ kg-year within r = 10 cm. Radial Distribtion: 35% within r = 10 cm 85% within r = 50 cm). 800 m 50 GeV 30m Near Detector Hall Not only is the event rate a factor 100 increase over NMI bt concentrated in center allowing smaller near detectors Magnetized Fe Shield 70m

18 The Vocablary of Deep Inelastic Lepton-Hadron Scattering Standard Kinematic Variables: Q 2 = 4EE'sin 2 θ/2 = -q 2 ν = E - E' x Bj = Q 2 / 2 M ν y = ν / E

19 The Advantages of Netrino DIS Experiments Netrinos have the ability to directly resolve flavor of the ncleon s constitents: ν interacts with d, s,, and c while ν interacts with, c, d and s. ν/ ν have definite spin/helicity states, which can be sed to determine partonic spin contribtion to the ncleon The ν is crrently a very hot topic becase of possible mass and conseqent oscillation phenomena tests. Very intense beams will be developed for this prpose. It s logical to se them for conventional physics also!

20 Althogh Sccessfl - ν DIS Stdies Can Be Improved 1) Heavy nclear targets have been reqired to accmlate sfficient statistics - measring ν - Fe not ν - N. 2) No high statistics measrement of these nclear effects (interesting in their own right). Had to assme ν - Fe same as µ/e - Fe to inclde ν data in global fits. Particlarly limiting for valence qark and high x parton distribtion fnctions 3) Statistics and systematics have not yet reached the level to allow extraction of all possible information. Independent ν and ν strctre fnctions have not yet been well measred. 4) Althogh CCFR/NTeV have made great progress. Beam systematics will still be a limit for high statistics experiments. 1) - 3) indicate need for more intense ν & ν beams while 4) sggests need for better knowledge of those beams

21 Global Fitting Needs Improved Statistics at high x. (Fit into the resonance region?) Improved estimate of s & s 10 2 DIS (fixed target) HERA ( 94) DY W-asymmetry Direct-γ Jets Improved nderstanding of leading exponential contribtion. Improved nderstanding of nclear corrections and/or ν - H 2 /D 2 Q (GeV) /X

22 How Do We Address these Needs? NMI Uses high intensity Main Injector (pls new Proton Driver?) with 120 GeV protons and horn focssed π & K beam for ν. A 2 nd generation higher energy DIS expt. cold happen > 2007? Knowledge of beam improved over other horn-focssed beams. Netrino Factory Uses mon storage ring with prodction of ν µ and ν e via decay of µ ± Entry level facility possible in time frame. Excellent knowledge of beam. Beam <E ν > (GeV) Evts/kg-year CCFR/NTeV 100 O(10) NMI (HE - configration) 17 (.3-1.0) x 10 4 ν Factory (25 GeV µ) 17 3 x 10 5

23 Compare Event Rates for Two Ftre Experiments MIDIS in the NMI Beam protons/year on the NMI target. (.3-1.0) x 10 4 CC ν or (.7-2.5) x 10 3 CC ν events /kg-yr (in high energy configration) Know φ(e ν ) and φ(e ν ) to < 2% First Beam HE beam rn > 2007 Near Detector/50 GeV NFact (50 m away from 800 m straight section) µ decays/year 4.5 x 10 6 CC ν µ and 1.9 x 10 6 CC ν e events/kg-year (fid. vol. r < 10 cm) Know φ(e ν ) and φ(e ν ) to < 1.0 % First Beam ?

24 What Information is yet to be Gained? [ ] [ ] [ ] [ ] F 2 ν Ν (x,q 2 ) = x++d+d+2s+2c F 2 νν (x,q 2 ) = x++d+d+2s+2c xf 3 ν Ν (x,q 2 ) = x+d--d-2s+2c xf 3 νν (x,q 2 ) = x+d--d+2s-2c What do we gain by measring separate ν and ν strctre fnctions? Does s = s and c = c over all x? If so... F ν 2 -F ν 2 = 2 ( s-s) + ( c-c) ν ν 2 3 F - xf = 2 + d + 2c 2U + 4c ν ν 2 3 F -xf =2 +d+2s =2U+4s ν ν 3 3 ( ) = ( ) [ ] xf - xf 2 s + s c + c = 4s - 4c = ( ) ( ) [ ]

25 The Challenge of d/ at High x John Arrington - ANL Netron Strctre Fnction. Ncleon strctre fnctions at large x are sensitive to valence qark distribtions. The ratio of F p 2 / F n 2 allows one to separate p and down qark distribtions. d p v/ p v ratio F n 2 / F p 2 SU(6) symmetry 1/2 2/3 diqark S=1 sppression 0 1/4 (Close, et al.; Carlitz, et al.) diqark S Z =1 sppression (Farrar and Jackson; Brodsky et al.) 1/5 3/7 Extracting the netron strctre fnction from deteron measrements reqires a model of the nclear effects. Proton and deterim data from SLAC E139 (L. W. Whitlow, et al.), and E140 (J. Gomez, et al.) On-shell prescription (W. Melnitchok, A.W. Thomas) (A. Bodek, S. Das, S.E. Rock) Off-shell prescription (W. Melnitchok, A.W. Thomas) Scaled EMC effect (A. Bodek, S. Das, S.E. Rock) (Frankfrt and Strikman) The extraction of F n 2 is limited by or nderstanding of nclear effects in deterim. A high statistics experiment with ν and ν off a hydrogen target gives d/ (relatively) cleanly [ ] F 2 νp (x,q 2 ) = 2x +d+s+c F νp 2 (x,q 2 ) = 2x[ +d+s+c] [ ] xf 3 νp (x,q 2 ) = x-d-s+c xf νp 3 (x,q 2 ) = x-+d+s-c [ ]

26 Near Detector for Netrino Factory Liqid hydrogen/deterim cryogenic target (followed by high A targets). All targets (r = 10 cm) acqire 10 7 ν µ events and 4 x 10 6 ν e /year. H 120 cm long or D 50 cm, 3.7 cm and 0.45 cm

27 The Complete Differential Cross Sections for High Energy Netrinos Physics at the Front-End of a Netrino Factory: A Qantitative Appraisal - M.L. Mangano et al - CERN-TH/ , May 15, 2001 d 2 σ νν dxdy = xf νν 1 (x,q 2 )y 2 d 2 σ νν dxdy = xf νν 1 (x,q 2 )y 2 G 2 F ME 2π( 1 + Q 2 2 M ) W + F νν 2 (x,q 2 ) ( 1 y )+ xf νν (x,q 2 )y 1- y 3 2 G 2 F ME 2π( 1 + Q 2 2 M ) W + F νν 2 (x,q 2 ) ( 1 y ) xf νν (x,q 2 )y 1- y 3 2

28 Expected Errors on Measred F s Deterim Target: r = 50 cm & l = 60 cm. One year exposre. Errors on F 1 betterthan 10%. As x--> 1.0, F 2 --> xf 3

29 Expected Errors on Measred F s Assme the Callan-Gross relationship eliminating F 1. Errors now O (1%) or better over most of the x- range.

30 Extracting the Strange Sea Crrent knowledge of s & s comes from CCFR/NTeV. Closely related to the c-qark distribtion. We mst independently measre charm or neglect it. 1 year ν and 1 year ν wold reslt in these errors on s + s Barone, Pascad and Zomer (BPZ) find evidence for intrinsic strange sea at high x.

31 BPZ is Qite Strange!

32 Extracting PDFs at a Netrino Factory Generate eight sets of fake data (F 2 and xf 3 for ν and ν on hydrogen and deterim) with errors as previosly shown. Central vales from Alekhin et al - charged lepton DIS. Dashed lines show error from Alekhin et al analysis

33 NFact-Specific Physics Topics: Polarized Target - M. Velasco Sfficiently intense and compact ν beam to envision reasonable statistics in O(10 kg) polarized target. Recent development of an ICE targets which is a solid polarizable HD material (ρ = 0.11 g/cm 3 ). P H = 80 % and P D = 50 %. ICE target with r = 20 cm and l = 50 cm wold accmlate 20 M events / year (10 20 µ). Cold also se more traditional polarized btanol target a la SMC with r = 6 cm and l = 60 cm wold get the same statistics bt with P = 0.1.

34 NFact-Specific Physics Topics: Reference For more details on the NFact topics covered in this brief smmary pls other topics sch as: Charmed Particle Prodction and Analysis Electroweak Physics Rare netrino properties sch as magnetic moment see The Potential for Netrino Physics at Mon Colliders and Dedicated High Crrent Mon Storage Rings, I. Bigi et al, BNL 68106, Jan (sbmitted to Physics Reports)

35 SUMMARY Netrino Oscillations have become more of a sre thing since the SNO reslts. Need to stdy the oscillations consistent with the atmospheric anomaly which will be done with K2K and MINOS. The qestion of whether we are dealing with the SMA or LMA solar netrino soltion will come from KAMLAND if not from SNO pls BOREXINO. To answer all the remaining netrino oscillation qestions we need either Sperbeams or a Netrino Factory based on a mon storage factory. A Sperbeam or a Netrino Factory with a near detector consisting of H 2, D 2, and nclear targets as well as polarized targets: Extract individal pdf s for each flavor in each x - Q bin. Complete measrements of the partonic spin strctre of ncleon. High statistics charm prodction with clean final state (E µ 50 GeV). Precision electroweak measrements; ν-e scattering.