Exotic BSM Physics and N-N oscillation R. N. Mohapatra University of Maryland

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1 Exotic BSM Physics and N-N oscillation R. N. Mohapatra University of Maryland K. S. Babu and R.N.M, PRD91, (2015); PRD94, (2016)

2 NNbar search and BSM physics Nnbar is a gold mine of informaeon on new physics in the mule- TeV range i.e. new colored scalars, new B- violaeng forces etc Requires a new way to look at the origin of marer- Post sphaleron baryogenesis; TeV scale origin of neutrino mass Possible conneceon to dark marer Today s talk: it provides a probe of some kinds of exotic BSM physics as well.

3 Searching for NN- bar oscilla<ons Two ways: (i) OscillaEon inside a nucleus leading to B- violaeng nuclear decays (ii) OscillaEon of a free neutron beam from a reactor or spallaeon source

4 Free neutron Oscilla<on Two state quantum mechanics: d ; dt n n n n = H H = M1 m Coherence requires high degree of degeneracy ;

5 Any new physics that splits N-N masses will be upper bounded? Examples of new physics (a) Lorentz violaeon (connected to CPT) (b) ViolaEon of equivalence principle (c) Strength of long range baryonic forces

6 Lorentz-violation for neutrons. L = L 0 + L LIV L 0 = i n µ n + m nn + n n n T C 1 n + h.c. B =0 Kostelecky, Colladay et al There could also be LIV terms with B = 0

7 Analysis of B=0 operator a 0 O LIV n n ( = a 0 ) M = 0 (n+, n+,n, n ) m + n n 0 0 n n m m n n 0 0 n n m + 1 C A Note the spli]ng of diagonal elements:

8 Condition for observability OscillaEon probability is modified to: P n n = apple 2 n n n n Nuclear decay searchesà 4 4 P n n = sin 2 n nt ~ p! ( 2 + n n)t 2 ~ n n apple GeV 2 sin y apple sin y y y 2 4 /2 2 (a 0 = )

9 Limit on LIV. sin y 2 y y

10 Condition for observability Current sensievity for deteceon of nnbar require and typically t~ 1 sec. n nt ~ From the shape of P n n, we see that for y t>3 (since n n t 1), we have à P n n << and hence unobservable Hence observaeon of nnbar at this level would imply that < 3 sec GeV

11 Restrictions on general LIV operators

12 Example of an operator that flips spin, changes B Breaks Lorentz invariance and changes mass matrix to With such operator, degaussing unnecessary. Non- observaeonà 0 LIV apple GeV

13 Speculation on possible origin of a 0 type LIV terms If baryon number is a spontaneously broken global sym., there will be massless field, derivaevely coupled to neutrons: 1 M n µ n@ µ As the universe cools, this field could have Eme dependent coupling 0 6=0 ; This will induce LIV terms of the form n n à will induce cosmological constant leading to (@ 0 ) 2 apple (10 3 ev) 4

14 Limit on Equivalence principle violation for neutrons If there is such a violaeon between marer and ane- marer, in the gravitaeonal field of Earth, Sun, galaxies, ( mass spli]ng) can be nonzero In a gravity field, m n =( n n ) GM Rc 2 Most stringent limit comes from superclusters for which M=5.4x10 46 Kg; R~43 Mpcà GM Rc 2 ' ( n n ) apple Limits from KK- bar <10-13 ; Dicke et.al. < 10-12

15 Limit on the strength of long range baryonic forces. If there are long range baryonic forces, the astrophysical bodies (Sun, Superclusters etc) will split the n- n masses and suppress free oscillaeon. ObservaEon of nn will then limit the strength of the strength of the forces: g B. Limit: B apple most stringent. (Babu, RNM 16; Adazzi,Berezhiani,Kamyshkov 16)

16 Some details PotenEal energy due to the new force: N B à - N B for ane- neutrons leading to mass spli]ng. R 0 ~(g B v B ) - 1

17 Gauge theory for such weak B- L force Such a B- L symmetry must not contribute to electric charge since if it did, we would have 1 e 2 = 1 gl g 2 R + 1 g 2 B à g 2 B >e 2

18 NN- bar vs Non- leptonic Nucleon decay Important point: All these conclusions rely on observaeon in free neutron oscillaeon and not observaeon of NN- bar in nucleon decay searches, where a Eny new spli]ng gets heavily masked by nuclear poteneal difference and does not lead to any constraints. u Free n- n- bar oscillaeon search therefore more potent source of theory informaeon than nuclear search or nn osc.

19 NN Oscilla<on Here a more or less exact discrete symmetry is esseneal. As a result, observaeon of NN does not limit the extent of Lorentz violaeon.

20 Conclusion u ObservaEon of NN- bar oscillaeon can more firmly establish the fundamental assumpeons of Quantum field theory. u It can also bound couplings for long range gauge forces.

21 More details. In the early universe, we have 00 +3H 0 + m 2 =0 As the universe evolves, is Eme dependent and leads to Lorentz violaeon of the type here: If scale of B- violaeon ~v B, 0 v B m

22 Another possible source Possible Lorentz violaeon in the dark marer sector, transmired to the visible sector: n DM =mirror neutron

23 Any CPT violating Requires high degree of degeneracy between N and N required to observe it: For transit Eme ~ sec., M apple GeV High degeneracy guaranteed by CPT inv; First obvious conclusion: ObservaEon of nnbar will give the new limit on CPT for neutrons will put CPT < GeV (be#er than for Kaons < 4x10-19 GeV)

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