Study of the Time-Reversal Violation with neutrons Angular correlations N and R nTRV@PSI Elctric dipole moment of neutron nEDM@PSI Adam Kozela Institute of Nuclear Physics, PAN, Cracow, Poland

T- and CP-violation Observations Theories II Low of Thermodynamics - „arrow of time” Byron Asymmetry of the Universe. Kaon decays: KL -> ππ (1964). First observation of CP violation, (1988, NA31) difference in decay of KL, KS to π0 π0 i π+ π- . Direct violation of T in kaon decays: (1998, CPLEAR, CERN), (2000, KTeV, Fermilab), KL-> π+ π- e+ e- . Many observations of CP violation in the decays of B mesons (BaBar, SLAC), (Belle, KEK). Recently: CP violation in the decay of D0 (LHCb). Direct observation of T-violation in entangled BB meson system. CP violation in CKM matrix, 3rd generation of quarks and imaginary phase δKM, θ therm in effective Lagrangian of strong interaction allows for CP violation without flavour change. Imaginary parts of coupling constants in weak interaction. Final state interaction.

Why neutron? It is neutral… (application of high electric fields possible). Long lifetime (886 sec, good and bad…). Decays by weak interaction (known from TRV). No effects from nuclear or atomic structure (for free neutrons exact value of MF, MGT). Small decay asymmetry A and small charges involved in decay => (small and precisely known final state interaction correction). Made of u and d quark (very small effect from KM-matrix).

Angular correlation in neutron decay p p Pp Jn (~885.7s) σT1 n -> p e νe + 782 keV - T p = - p σT2 T s = - s T J = - J A- decay asymmetry (-0.1173) R, N – Correlation coefficients

Korelacje kierunkowe w rozpadzie neutronu Pp Jn σT1 σT2 PDG: = -0.1188(7) = -0.2377(25) = 0.9807(30) = -0.0004(6) = -0.103(4)

Correlation coefficients N, R and exotic interactions Contribution from complex phase δKM and θ-term negligible (~10-12). Allowing for nonzero exotic couplings in weak interaction (Jackson, 57): NFSI~0.068 6∙10-4 RFSI~0.0006 6∙10-6 Beyond Standard Model: S, T – relative strength of scalar and tensor couplings Standard Model Final state interaction N measurement: detector test (Re(S), Re(T) known well from other experiments). If measured R≠0 new mechanism of T-(CP) violation, limit on Im(CS) i Im(CT).

Experimental setup (Mott Polarimeter), top view V-track

Correlation coefficients N and R our result NFSI~0.0686∙10-4 RFSI~0.00066∙10-6 Former limmitations NSM·100 RSM·100 N ·100 R·100 68 0.6 62115 4125

Correlation coefficients N and R our result NFSI~0.0686∙10-4 RFSI~0.00066∙10-6 Former limmitations And our result [Phys. Rev. C 85, 045501] N = (62115)·10-3 R = (4125)·10-3

Correlation coefficients N and R, our result First measurement of correlation coefficients R i N in neutron decay is consistent with Standard Model expectations and with Time Reversal Symmetry. N = (62115)·10-3 R = (4125)·10-3

Electric Dipole Moment Simple case: Particle with spin: +Q -Q   e       + _   + _       + _ Electric dipole moment of particle with spin Violates both Parity and time Reversal Symmetry

nEDM – predictions θ-term from QCD Lagrangian: even ~10-18 e·cm. nEDN [e·cm] θ-term from QCD Lagrangian: even ~10-18 e·cm. ~10-9 „Strong CP-problem” Current limit: 2.9·10–26 e·cm. nEDM@PSI final goal: 5·10-28 e·cm Contribution from complex phase δKM negligible below ~10-32 e·cm.

nEDM current precision dn=(+0.2 ± 1.5 ± 0.7)·10-26 e·cm. n d ≈ 2 µm

nEDM @ Paul Scherrer Institute [successor of RAL,Sussex,ILL] Ramsey resonance method of separate oscillating fields applied for Ultra Cold Neutrons. UCN; v<10m/s

Ramsey resonance method of oscillating fields - principle Sample of polarized neutrons In constant, uniform fields B (1 μT) and E (12 kV/cm). RF „π/2” pulse (30 Hz). Free precession of neutron spin T ~ 150200 s. E↑↑B: ωL+ = 2/ћ(μnB + dnE) E↑↓B: ωL- = 2/ћ(μnB - dnE) dn = ћ/4 ·Δω/E Second „π/2” pulse. Analysis of neutron polarization. 1. 2. E 3. or 4. 5.

Ramsey resonance method of oscillating fields - principle Statistical uncertainty: C2 where: visibility E: electric field intensity, T: free precession time N: number of neutrons counted after T. x – working points

nEDM @ PSI improvements UCN source, 1000 UCN/cm3 Magnetometry and magnetic field control Solid D2,30l,~5K New shielding Surrounding Field Compensation New co-magnetometers… …

Współczynniki korelacji N i R a amplitudy wymiany leptokwarków spin 1 2/3 F f Q 1/3 H h Wcześniejsze ograniczenia i nasz rezultat LQ-wektorowe N = 62115 R = 4125

Minimalny Supersymetryczny Model Standardowy z łamaniem parzystości R