Recent Results from T2K

Transcription

1 Recet Results from T2K Alessadro Bravar o behalf of the T2K Collaboratio TAU 2016 Beijig Sept. 22, 16

2 The T2K Experimet 11 coutries ~500 members 2

3 JPARC - accelerator complex NA61 hadroproductio far detector Super Kamiokade ear detectors Off-axis: ND280 O-axis: INGRID 3

4 Neutrio Source at J-PARC (ati-) beam is created i the decay i flight of p / K / μ produced by iteractios of 30-GeV protos o a 90-cm log graphite rod off-axis eutrio beam Very arrow eergy spectrum Neutrio beam eergy tued to oscillatio maximum Reduced high-eergy tails E almost idepedet of paret pio eergy Neutrio beam predictios rely o experimetal hadro-productio data (NA61) for modelig the primary proto beam iteractios i the T2K target Hor focusig cacels partially the p T depedece of the paret meso 4

5 Data Collected Reached beam power of 420 kw Accumulated POT - protos o target (May 27, 2016) i total i mode i mode 5

6 3 Flavor Neutrio Mixig Flavor eigestates Potecorvo-Maki-Nakagawa-Sakata Matrix (CKM matrix of lepto sector) q 23 = 45 0 SuperK (atm. ) K2K / Mios T2K e 1 U,,, PMNS CP q 13 ~ 8 0 Daya Bay Reo T2K q 12 ~ 34 0 solar KamLAND Mass eigestates icp cosq13 0 siq13e cosq12 siq i /2 0 cosq23 siq siq12 cosq e 0 icp i /2 0 siq23 cosq 23 siq13e 0 cosq e eutrioless double beta decay NuFIT

7 Neutrio Oscillatios ad Time Evolutio ( t 0) E ν t=0 ie ( t ) t U i i U i e i i e 2 2 t t U i U i U i U i U i U i i i j P S13 23 si E m31 e ( ) ( 0) e m L 2a P 4 C S ( 1 (1 2 S )) e m32l m31l m21l 8 C13 S12S13S23( C12C23 cos S12S1 3S23) cos si si 4E 4E 4E m32l m31l m21l 8C13 C1 2C23S12S13S23 si si si si 4E 4E 4E m21l 4 S12 C13 ( C12 C23 S12 S23 S13 2C12C23S12S23S13 cos ) si 4E al m3 2L m3 1L 8 C13 S13 S23 (1 2 S1 3 ) cos si 4E 4E 4E 6 idepedet parameters gover oscillatio i i t j i -i(e -E ) t leadig, q 13 drive CPV E i solar matter effects CPC q 12, q 23, q 13, cp, m 122, m 232, m e p 2 mi 2 p m m m ij i j

8 e Appearace ad Oscillatio Parameters 8 mass orderig si 2 2q 13 ad si 2 q 23 leadig terms octat depedece, whether q 23 > 45 0, q 23 = 45 0, or q 23 < 45 0 CP : +- 27% effect at T2K for q 23 = 45 0 CP = ~p/2: ehaces suppresses CP = ~+p/2: suppresses ehaces mass hierarchy: +-10% effect at T2K ormal: ehaces suppresses iverted: suppresses ehaces e P e P e P e P e P e P e P e P

9 Neutrio Oscillatio Aalysis Overview e N ~ E E P FD FD FD FD Observed rate of ad e costrais the oscillatio probability P. Depeds o: Neutrio flux predictio Neutrio crosssectio model Far Detector selectio & efficiecy Reduce the error o the rate of with the ear detector measuremets. E E N ~ ND ND ND ND Neutrio flux predictio Neutrio crosssectio model Near Detector selectio & efficiecy 9

10 Oscillatio Aalysis Strategy data drive NA61/SHINE Data Flux Model ND280 Detector Model T2K Near Detector Data INGRID/Beam moitor Data Exteral Cross-sectio Data Crosssectio Model ND280 Fit ND data reduces flux ad cross-sectio ucertaities T2K Far Detector Data Oscillatio Fit Super-K Detector Model Oscillatio Parameters I the latest aalysis, the,, e, ad e samples are fit simultaeously to maximize the sesitivity to the oscillatio parameters 10

11 Sources of Systematic Ucertaities Neutrio flux Near Detector respose FGD TPC TPC ECAL FGD Muo-like track Neutrio iteractios Example: eutrio cadidate i atieutrio mode Far Detector respose 11

12 Neutrio Flux Predictios T2K, PRD87 (2013) Neutrio mode operatio Atieutrio mode operatio π + µ + π - µ - ν µ ν µ Data drive (NA61) FLUKA/Geat3 based eutrio beam simulatio Sigificat wrog sig compoet i atieutrio mode icreases i evet rate due to lower atieutrio cross sectio Itrisic electro eutrio compoet ~0.5% ear the peak 12

13 Absolute Neutrio Flux Ucertaities Beamlie related ucertaities proto beam profile off-axis agle hor curret ad field Hadro iteractio model ucertaities NA61 ucertaities re-iteractios secodary hadro productio At T2K peak eergy, flux ucertaity has decreased to ~10% ew NA61 data Domiat flux ucertaities stem from hadro iteractios Ucertaities are comparable for eutrio mode ad atieutrio mode operatio Replica target data from NA61/SHINE is beig icorporated i the T2K flux predictio reduce further systematics 13

14 The ND280 Near Detector Costrais eutrio flux before oscillatios (CC ad data) Measures eutrio iteractios o scitillator (CH) ad water targets 0.2 T magetic field Plastic scitillator detectors (FGD, POD, ECALs, SMRD) FGD TPC TPC ECAL FGD Time Projectio Chambers better tha 10% de/dx resolutio Muo-like track Muo mometum, sig from curvature i magetic field 10% mometum resolutio at 1 GeV/c Example: eutrio cadidate i atieutrio mode 14

15 Neutrio Iteractios Oscillatio probability depeds o eutrio eergy. I T2K eergy rage, domiat process is Charged-Curret Quasi-Elastic CCQE Neutrio eergy from measured lepto mometum ad agle 2-body kiematics ad assumes the target ucleo is at rest Additioal sigificat processes: CC1p NC1p CCQE-like multi-ucleo iteractio Charged-curret sigle pio productio (CC1π) Neutral-curret sigle pio productio (NC1π) 15

16 Improved Neutrio Iteractio Model Most recet NEUT geerator tued to exteral data (MiiBooNE ad MINERA) Improved CCQE descriptio: uclear effects (Fermi Gas + RPA) uclear correlatios (MEC 2p2h) fial state iteractios (FSI) Resoat p productio retued Tesios with some data sets remai. Cross-sectio model ucertaities come from uderlyig model parameters ad ormalizatio. Expected umber of evets at the far detector is tued usig a bied likelihood fit to the ND280 data (i bis of p ad q ) takig ito accout variatios i the flux model parameters cross-sectio model parameters ND280 detector ucertaities Neutrio iteractios separated i CC0p, CC1p, CCNp (# of outgoig ps) NEW iteractios i ND280 H 2 0 target icluded 16

17 ND280 Costraits for Far Detector eutrio mode example CC0p before costrait CC1p before costrait CCNp before costrait The data is i better agreemet after the flux ad ND280 costraits CC0p after costrait CC1p after costrait CCNp after costrait 17

18 T2K Typical Evets (Far Detector) good e separatio simulated evet display (FD respose) backgroud for e appearace: itrisic e compoet i iitial beam merged p 0 rigs from NC iteractios good p 0 rejectio (2 rigs from g coversio) 18

19 / Disappearace P 2 2 2m32L ~ 1si 2q 23 si 4E 135 evets observed 66 evets observed (135.8 ev. expected*) (64.2 ev. expected*) *with si 2 q 23 = 0.528, m 2 32 = ev 2, CP = from the fit to the,, e, ad e samples ad si 2 q 13 = from PDG

20 q 23 ad m 2 32 Normal Hierarchy Iverted Hierarchy si si 2 2 m 2.34, ev at 90% CL q ,0.61 at 90% CL m 2.34, ev at 90% CL q 0.32,0.70 at 90% CL 20

21 q 23 ad m 2 32 DayaBay 2 m ev 2 ee at 90% CL (NH) cosistet with maximal mixig 21

22 e Far Detector Selectio distributio of e iteractio vertices i SK 22

23 e / e Appearace e e 32 evets observed 4 evets observed expected umber of evets (NH, si 2 q 23 = 0.53) observed CP = -p/2 CP = 0 CP = +p/2 CP = p e e

24 q 13 vs CP with reactor costrait T2K oly (si 2 2q 13 = ) 90% CL allowed regios Feldma-Cousis critical c 2 values for 90 % C.L. reactor q 13 T2K-oly result cosistet with reactor measuremets Favors the CP ~ - p/2 regio ormal hierarchy: CP = [-3.13, -0.39] [-179 0, ] at 90% CL iverted hierarchy: CP = [-2.09, -0.74] [-120 0, ] at 90% CL 24

25 T2K to T2K-II Proposal to exted T2K ru to POT Curretly approved to POT J-PARC mai rig power supply upgrade is approved (reduce cycle from 2.48 sec to 1.3 sec) Accelerator ad beam lie upgrade aimig at > 700 kw operatio ND280 upgrades uder discussio 25

26 Physics Potetial of T2K-II Mass Hierarchy ukow arxiv: Mass Hierarchy kow 50% icrease i effective POT reductio of systematic errors 3 sesitivity to CP violatio for favorable (ad curretly favored) parameters precise measuremet of q 23 (to or better) assumig si 2 q 23 =

27 Coclusios Accumulated ~ protos o target (POT) equally split i -mode ad -mode Beam power cotiuously icreasig (420 kw at the ed of ru 7) Fully joit aalysis across all modes of oscillatio / disappearace ad e / e appearace Near detector ad NA61 hadroproductio data used to costrai rate at far det. water target ad wrog sig from ND280 Data prefer maximal q 23 mixig, CP ~ -p/2, ormal hierarchy maximal / disappearace, large e appearace, small e appearace CP = [-3.13, -0.39] at 90% CL (NH) CP = [-2.09, -0.74] at 90% CL (IH) Accelerator upgrade approved, aimig for > 700 kw operatio Proposal to exted T2K (T2K-II) 27

28 additioal material 28

29 QE Axial Mass Carbo Fermi mom. Carbo 2p-2h orm. Carbo bid. eergy Oxyge Fermi mom. Oxyge 2p-2h Oxyge bid. eergy Cross-Sectio Tuig Cross-sectio model is propagated to far detector rate Parameters cotrol CCQE model, multi-ucleo ad resoace model Some cross-sectio parameters (2p2h o C ad O, M A RES ) chaged sigificatly compared to exteral prior values I geeral error o parameters is decreased 29

30 Flux Tuig Muo eutrio / atieutrio flux correlates to electro eutrio / atieutrio flux Icreased flux preferred with ew cross-sectio model predicted flux at far detector is geerally icreased 30