Download
slide1 n.
Skip this Video
Loading SlideShow in 5 Seconds..
Neutrinos at the High Energy Frontier PowerPoint Presentation
Download Presentation
Neutrinos at the High Energy Frontier

Neutrinos at the High Energy Frontier

76 Vues Download Presentation
Télécharger la présentation

Neutrinos at the High Energy Frontier

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Neutrinos at the High EnergyFrontier

  2. MOTIVATION The onlyknown BSM physics at the particlephysicslevelis the existence of neutrino masses -- There is no unique solution for mass terms: Diraconly? Majoranaonly? Both? -- if Both, existence of (2 or 3) families of massive right-handed (~sterile) i ,i neutrinos ispredicted («see-saw» models) masses are unknown (<eV to >1010GeV) -- Arguably, right handed neutrinos are the mostlikely ‘new physics’ thereis -- can high energyparticlephysicsexperimentsparticipate to the search?

  3. Adding masses to the Standard model neutrino 'simply' by adding a Dirac mass term impliesadding a right-handedneutrino (new particle) No SM symmetrypreventsaddingthen a termlike and thissimplymeansthat a neutrino turnsinto a antineutrino (the charge conjugate of a right handed antineutrino is a lefthanded neutrino!) It isperfectlyconceivablethatbothterms are present ‘see-saw’

  4. See-saw in the mostgeneralway : MR 0 mD  0 Dirac + Majorana mass terms MR 0 mD  0 Dirac + Majorana L NR R NL ½ 0 ½ 0 4 states , 2 mass levels MR = 0 mD  0 Dirac only, (like e- vs e+): L R R L ½ 0 ½ 0 4 states of equal masses MR 0 mD = 0 Majorana only L R ½ ½ 2 states of equal masses m m m Iweak= Iweak= Iweak= Some have I=1/2 (active) Some have I=0 (sterile) All have I=1/2 (active) m1 have I=1/2 (~active) m2 have I=0 (~sterile)

  5. Neutrinos : the New Physicsthereis… and a lot of it! Mass hierarchies are all unknownexcept m1 < m2 Preferred scenario has bothDirac and Majoranaterms … … a bonanza of extremeexperimental challenges

  6. Note thatthisis not necessary as we have no ideaof mD and MR !

  7. = has been invoked to explain the smallness of active neutrino masses (maybe)  is a pretty large hierarchyproblemis’ntit? ... but we dont really know thatthisimplies M  MGUT northat the see-sawmixingissmall norwhatis the familydependence of thisreasoning.

  8. Manifestations of right handedneutrinos = light mass eigenstate N = heavy mass eigenstate  which couples to weak interaction cos -  for onefamily see-saw   (mD/M) c sin -- mixingwith active neutrinos leads to various observable consequences -- if very light (eV) , possible effect on neutrino oscillations -- if mixing in % or permillevel, possiblymeasurableeffects on PMNS matrix unitarity violation and deficit in Z invisible width occurrence of Higgs invisible decays H ii violation of unitarity and lepton universality in W or decays -- etc etc.. -- Couplings are small(mD/M) (but whoknows?) and generally out of reach of hadron colliders -- how about high statisticse+e- ?

  9. Back to the future 30 yearslater and withexperiencegained on LEP, LEP2 and the B factories wecan propose a Z,W,H,tfactory of 1000 times the luminosity of LEP2 CERN islaunching a 5 years international design study of CircularColliders 100 TeV pp collider (VHE-LHC) and high luminositye+e- collider (TLEP) -- kick-off meeting 12-15 February 2014 in Geneva --

  10. IPAC’13 Shanghai http://arxiv.org/abs/1305.6498. Z WW ZH tt CONSISTENT SET OF PARAMETERS FOR TLEP TAKING INTO ACCOUNT BEAMSTRAHLUNG Will consideralso : x10 upgrade withe.g. charge compensation? (suppressesbeamstrahlung and beam-beamblow up)

  11. Goal performance of e+ e- colliders complementarity Combined know-how {LEP, LEP2 and b-factories} applied for large e+e- ring collider High Luminosity + Energyresolution and Calibration  precision on Z, W, H, t • Luminosity : Crossing point between circular and linear colliders ~ 4-500 GeV As pointed out by H. Shopper in ‘The Lord of the Rings’ (Thanks to Superconducting RF…)

  12. STATISTICS(e+e- ZH, e+e- →W+W-, e+e- →ZH,[e+e-→t ) at the Z pole repeat the LEP physics programme in a few minutes…

  13. to appear in JHEP

  14. best-of FCC/TLEP #2: Precision EW measts Asset: -- high luminosity (1012 Z decays + 108 Wpairs + 106 top pairs ) -- exquisteenergy calibration up and above WW threshold targetprecisions Also -- sin2 W10-6 -- S= 0.0001 from W and Z hadronicwidths -- orders of magnitude on FCNCs and rare decayse.g. Z , e, e in 1011 Zlleventsetc. etc. Design study to establishpossibility of theoreticalcalculations of correspondingprecision.

  15. NB without TLEP the SM line would have a 2.2 MeV width in otherwords .... ()=  610-6 +several tests of sameprecision

  16. Neutrino counting In October 1989 LEP determinedthat the number of neutrino familieswas 3.110.15 In Feb 1990 Cecilia Jarlskogcommentedthatthisnumbercouldsmallerthan 3 if the lefthanded neutrino(s) has a component of (a) heavysterile neutrino(s) whichiskinematicallysuppressed or forbidden

  17. Atthe end of LEP: Phys.Rept.427:257-454,2006 N = 2.984 0.008 - 2  :^) !! Test of the unitarity of the PMNS matrix This isdeterminedfrom the Z line shape scan and dominated by the measurement of the hadronic cross-section at the Z peakmaximum  The dominant systematicerroris the theoretical uncertainty on the Bhabha cross-section (0.06%) whichrepresents an error of 0.0046 on N Improving on N by more than a factor 2 would require a large effort to improve on the Bhabha cross-section calculation!

  18. Another solution: determine the number of neutrinos from the radiative returns e+e-   Z ( vv ) in its original form (Karlen) the methodonlycounts the ‘single photon’ events and isactuallyless sensitive thanclaimed. It has poorerstatistics and requires running ~10 GeVabove the Z pole. Systematics on photon selection are not small. presentresult: Nv= 2.920.05

  19. Neutrino countingat TLEP given the very high luminosity, the followingmeasurementcanbeperformed • The common tag allowscancellation of systematics due to photon selection, luminosity • etc. The others are extremelywellknown due to the availanbility of O(1012 ) Z decays. • The full sensitivity to the number of neutrinos isrestored , and the theoryuncertainty • on is veryverysmall. • A good measurementcanbe made from the data accumulatedat the WW threshold • where ( Z(inv) ) ~4 pb for |cos| <0.95 • 161 GeV(107 s) running at 1.6x1035/cm2/s x 4 exp 3x107 Z(inv) evts,  =0.0011 • adding 5 yrs data at 240 and 350 GeV ............................................................  =0.0008 • Optimal (but dedicated ) point at 105 GeV (20pb and higherluminosity)   =0.0004? • understudy.

  20. ILC Z – tagging by missing mass total rate  gHZZ2 ZZZ final state  gHZZ4/ H  measure total widthH emptyrecoil = invisible width ‘funnyrecoil’ = exoticHiggsdecay easy control belowtheshold e- H Z* Z e+

  21. best-of FCC/TLEP #1: Higgsfactory (constrained fit including ‘exotic’) 4 IPs (2 IPs) 2 106 ZH events in 5 years «A taggedHiggsbeam». sensitive to new physics in loops Best across the board invisible width = (darkmatter?) also (but betterdone at the hadron colliders HL-LHC, VHE-LHC: 0.6% 28% 13% total width HHH Htt fromeffect on HZ threshold arXiv:1312.3322v1 fromeffectonttthreshold

  22. Higgs Decay into nu + N Chen, He, Tandean, Tsai (2011)

  23. arxiv:1208.3654 LEP2 limits (DELPHI) (projected)

  24. Conclusion and invitation The study of Future CircularCollidersisstarting (CERN, China), including high luminosity e+e- collider. Precisemeasurements of the invisible Z and Higgswidthscanbe made usingtagging: e+e-  Zande+e-  ZH There are certainlymany more variables thatwillbe sensitive to the existence of heavy right handedneutrinos What about an ‘invisible’ phenomenologyworking group for the FCC study?