Unique probe of neutrino electromagnetic moments with radiative pair emission

Disentangle neutrino electromagnetic properties with atomic radiative pair emission

“…The advantage of RENP is its capability of separating the individual form factor elements f ij M,E,Q,A of eq. ( 2.3) as first noticed in [29]. From the hermiticity condition, each form factor contains 6 elements that enter the spectral function as magnitudes squared |f ij M,E,Q,A | 2 while their phases do not appear.…”

“…A single or just a handful of observations cannot disentangle and identify individual form factor elements. One possible solution [29] is the radiative emission of neutrino pair (RENP) from excited atoms [30][31][32][33][34][35]. Since atomic transition energies are typically O(eV), close to the neutrino mass values, RENP is an ideal place to test the light mediators that couples with neutrino and electrons [36], including the massless photon.…”

“…For the SM interactions and Dirac neutrinos, the neutrino pair emission matrix element is [29][30][31]64],…”

“…With the trigger laser having a precision of δω ∼ 10 −5 eV [31] which is much better than E eg /2 − ω max ij ∼ 10 −5 − 10 −3 eV, it is possible to scan the various thresholds ω max ij with different combinations of neutrino mass eigenvalues and the regions in between. Scanning over 6 frequencies is sufficient to separate individual matrix elements as proposed in [29]. For illustration, we take ω i = (1.069, 1.07, 1.0708, 1.0712, 1.0716, 1.07164) eV shown as the black points in figure 2.…”

Neutrino mass measurement with cosmic gravitational focusing

“…With both superradiance and macroscopic coherent material, the RENP process that is induced by weak interactions can be significantly enhanced [52,53]. Since the typical energy of atomic transitions is intrinsically at the O(eV) scale, RENP can be sensitive to not just light/massless mediators [54][55][56] but also those properties that are attached to the neutrino mass terms [57,58]. In particular, the (10 −3 ∼ 10 −2 ) eV neutrino mass eigenvalues can leave a visible effect in the associated photon spectrum and hence can be measured by RENP [59,60].…”