NF01 Topical Workshop No. 4



October 2, 2020: NF01 Workshop #3 on the importance of precision, DUNE, and T2HK.


Precision (Petcov):
- Determining neutrino parameters is important, including CP, mass ordering, mass scale
- Lots of BSM models connect with oscillations
- CP violation in Dirac phase could be large given data, Majorana phases are hard to measure
- Evidence for NO has decreased with 2020 data
- The three mixing angles are a challenge to explain theoretically
- Non-abelian discrete symmetries are popular explanations
- Perhaps there are perturbative corrections to tribimaximal
- Base symmetries predict theta13=0, theta23=45, and differ on theta12.
- In different models there are relationships among the different mixing angles including delta
- DUNE and T2HK have about 2-3sig sensitivity for discriminating different models
- Useful precision: s12sq=.7%, s13sq=3%, s23sq=3%, delta=10-12deg at 3pi/2
- Kevin Kelly: There has been a lot of focus on the mixing angles. What about the masses? Petcov: mixing angles are harder to explain than the masses. Kevin: What about quasi-degenerate vs hierarchy? Petcov: Everything is possible.

DUNE (Worcester):
- Goals to measure CP, mixing angles, mass ordering in one experiment as well as rare processes and low energy physics.
- Beam will be upgraded to 1.2 MW upgradeable to 2.4 and is broadband with three focusing horns
- Near detector: constrain systematics for oscillation analysis (plus cross sections and BSM). Contains LAr, GAr, and tracker. The first two move off-axis 30m for PRISM.
- Far detector 40kt fiducial of LArTPC. Some of the design is to be determined. ''It's huge.''
- Beyond oscillations: SN burst, BSM processes in oscillations, in the detector, and in the near detector.
- New sensitivity analyses include a very serious treatment of systematics at all stages including unknown unknowns.
- Precision on deltaCP: After 7yrs (staged) the precision will be 15-25deg (depending on true value), after 15yrs it will be  7-17deg.
- Precision on theta13 is competitive with current global fit on theta13.
- Discovery for mass ordering is well over 5sig, possible after 1-3yrs.
- Discovery for CPV (ruling out CPC) could be 5sig after 7yrs for some values, for 15yrs many values
- theta23 octant: more sensitivity for lower octant, considerably improved theta23 precision over current measurements
- Unknown unknowns: compare generator uncertainties: ND could identify generator uncertainties
- PRISM further identifies cross section uncertainties
- Combining ND and FD one can also constrain BSM e.g. sterile mu->e appearance
- Construction: FD construction is underway. ND planning is underway. FD physics data expected late 2020s. Details will be finalized in 2021.

T2HK (Nadadaira):
- HK construction started 2019, operation to start mid 2027
- Beam upgrade to 1.3 MW by 2026
- 2.7e22 POT in 10yrs is expected
- 1:3 nu:nubar beam ratio is assumed, O(2k) appearance events
- Systematics start with T2K18. Improved with stats and ND280 upgrade.
- Good sensitivity to delta, comparable to DUNE.
- Okay mass ordering sensitivity, 4-6sig in 10yrs.
- Good sensitivity for the theta23 octant
- nue/nuebar cross uncertainty is very important
- Denton: sensitivities w/wo mass ordering prior? Friend: nearly all plots assume mass ordering prior

Worcester: 1.2->2.4 MW upgrade is important
Kelly: Early stages of running to get mass ordering ASAP
Joint fits should be a priority in the Snowmass report
Megan: T2HK should prioritize unknown unknowns
Petcov: Not sure if delta sensitivities are good enough, combined could be

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