2. XVth Rencontres du Vietnam 2019: Three Neutrinos and Beyond
The theme of the meeting will be based on the 30th anniversary of the first collisions
in SLC (April 1989) and LEP (August 1989), which was followed very quickly
by the discovery that there are
only three families of light active neutrinos
The program will address the present status of neutrino properties and oscillations
and beyond: the searches towards the understanding of the origin of neutrinos masses
and its consequences (in particular leptogenesis and why we exist at all).

3. Concluding remarks.
1. goals of the meeting
2. the main questions
neutrinos (nue,numu,nutau)
if it had not been for the discovery of oscillations,
this might have been the end of neutrino physics
no!because of the solar neutrino problem...
3. origin of masses
the status of the mass hierarchy
the importance of T2K+NOvA, JUNO, SK+GD & ICECUBE ORCA
4. CP violation
the status of CP violation
5. the near future
we can predict that the hierarchy will be known soon from
T2K+NOvA, more data from ICECUBE, data from SK-Gd, then JUNO, ORCA, then DUNE.
6. the longer future
HyperK, DUNE, more huge project such as ORCA+Protvino etc..
the need for more neutrino interaction study
new beams, EnuBET and nuSTORM
--> need to work on the customers and synergies!
7. the origin of neutrino masses
neutrinos have mass --> new physics
yukawa coupling = mass term --> RH neutrinos (chirality!)
Majorana mass term by Weinberg operator --> but what is the scale?
NB we do not understand the Yukawa masses but at least we know them.
more or less any scale above pion mass can do the job of matter asymmetry
the dark matter with one particle requires keV mass range.
other related topic might give us more hints
8. neutrinoless double beta decay (fermion number violation)
9. search for right-handed neutrinos
eV sterile neutrino
beware the sigmas when there are assumptions!
heavy neutral leptons
new generation of hadron experiments
hadron collider experiments
e+e- Z factory, precision measurements & tau decays
the long lived region.
the high energy region --> very difficult!
10. the heavy neutrino search in hadron colliders is a new experiment!
new trigger, new detector optimization
at least one FCC detector to be optimized for RH neutrino search!
11. BIG REMARKS
-- we are nearing the time when the neutrino oscillation phenomenon will be entirely specified
(mass hierarchy CP phase, octant)
-- what will neutrino physics become then?
-- mass scale (compare KATRIN results with ccosmological)
-- however we need unambiguous mass measurement (how? more of KATRIN, Project 8, etc...)
-- the topic will certainly move to search for origin of neutrino masses
-- maybe the easiest of the 'search for origin of particle mass' questions.
-- a Z factory seems the most straight forward solution
-- one or several HUGE neutrino-less double beta decay experiment?
12 thanks the organizers
-- parallel sessions became serial sessions!

4. new data this year
main result:
normal mass ordering is very much preferred
at 2 = (3.2 sigma)
NB this is quite significant for such a
well-defined predefined bimodal test!
(many argue that 5 sigma not needed)
NBB note importance of atmospheric (SK)
watch T2K+NOvA, ICECUBE, SK+GD, ORCA… ... DUNE (matter effect)
JUNO (direct dephasing meast)
it should not take long before the question is solved!

5. With the data we have today
(175 ee events)
-- Mass Ordering is nearly surely normal
-- the measurement of the CPV phase
CP = - ( )o still ways to go.
careful: error depends on value.
-- sensitivity to octant comes from
e appearance (sensitive to sin2 23 )
this issue (and its relevance)
will simply disappear in the near future
with more statistics.

7. Gd in SuperK! improve sensitivity to -- relic SN neutrinos
-- atmospherics ( MO and CPV)
-- T2K beam (esp. run!)

8. Another cornerstone -oscillation experiment (MO from phase measurement, not matter effect)

9. HYPERK and DUNE are now on orbit  2027!
main mission: measurement of CP and test of CP violation+ many oter things incl. p decay!
They will measure CP to precison depending on value… but CPV discovery not guaranteed!
Quality of the results will be conditionned by measurements of (anti) e vs  cross-sections and properties (energy shifts in particular)  EnuBET/NUSTORM + hadrop. exp. NA61

10. where are the right-handed neutrinos?
3 neutrinos and beyond
it is a daily observation that neutrinos are leaning to the left:
where are the right-handed neutrinos?
neutrino Yukawa coupling  RH neutrino exists
+ if Majorana mass term exists (matter  antimatter transition)  mass splitting and mixing
NB in see-saw all neutrinos are Majorana particles with mixing btw. left and right-handed
NBB terminology refers to the chirality of the particle (not the helicity)
NBBB in the weak interaction, right-handed is equivalent to sterile

12. Deppisch showed us that signal  Majorana mass term
However Majorana mass term may (accidentally) not give a signal

15. It is a novelty of this meeting that so much emphasis was given to the searches for
right-handed (or sterile) neutrinos.
It is a novelty of the time that so much attention is paid by the high energy physics community to this search
-- eV scale neutrino oscillation experiments (reactor, short and long baseline)
-- BELLE/BELLE II, ATLAS&CMS, LHCb, FASER, MATHUSLA
-- NA62, NA64, SHIP….
one family see-saw  ||2 = mv/mN
eV scale mv = 50 meV neutrino  ||2 = 0.05 for mN = 1 eV
(this is ~ the LSND value, but this one is ‘ruled out by disappearance expts.)
However we do not know that mv is 50 meV
||2 down to 0.01 (0.08) is excluded for  (resp e )
there is plenty of space left for another sterile neutrino in that mass range!
 in three family see-saw ||2  mv/mN

16. SB expts..

18. In general these experiments offer many opportunities!

20. Alain Blondel FCC CDR presentation Outlook
Heavy neutrinos
FCC-ee Z
or 𝑙 +
(*)
FCC-hh -
FCC-ee
-- EWPO : sensitivity 10-5 up to very high masses
-- high sensitivity to single N( 𝑙2 W) in Z decay
FCC-hh
-- production in W-> 𝑙1 + N( 𝑙2 W)
with initial and final lepton charge and flavour
FCC e-p
-- production in CC e p  X N( 𝑙W) high mass
Complementarity:
discovery + studies of FNV and LFV!
Detached
vertices
The capability to probe massive neutrino mechanisms for generating the matter-antimatter asymmetry in the Universe should be a central consideration in the selection and design
of future colliders. (from the neutrino town meeting report to the ESPP)
Alain Blondel FCC CDR presentation Outlook

21. Parallel sessions (3-6 hrs each) Serial
Present status of neutrino oscillations and future prospects
Convener Son Cao + Tsuyoshi Nakaya
(include cross-section issues)
2. Experimental searches for sterile/RH/HNL/Majorana neutrinos
Conveners B. Kayser and Joachim Kopp
neutrino beams, astronomy, beam dumps, colliders
3. Other manifestations of neutrino mass models
Conveners Martin Hirsch and Marcin Chrząszcz
 neutrinoless double beta decay, manifestations of LFV and LNV, LUV, proton decay…
4. experimental techniques
Conveners Davide Sgalaberna + Ornella Palomara

22. Program committee Jacques Dumarchez Marcin Chrząszcz Raj Gandhi
Boris Kayser
Manfred Lindner
Sotiris Loucatos
Tsuyoshi Nakaya
Ornella Palomara
Davide Sgalaberna

24. Son Cao and Tran Than Van
Let us wish success to
Son Cao and Tran Than Van
in establishing a neutrino group in Quy Nhon!