Atomic deexcitation emitting a neutrino pair and a photon is expected to provide a novel method of neutrino physics if it is enhanced by quantum coherence in a macroscopic target. However, the same enhancement mechanism may also lead to a serious problem of enhanced QED background process. We show that the QED background can be suppressed enough in the photonic crystal waveguide by using the spatial phase that is imprinted in the process of initial coherence generation in the target at excitation.
We evaluate the O(alpha) QED corrections to the recoil electron energy spectrum in the process nu_l + e --> nu_l + e (+gamma), where (+gamma) indicates the possible emission of a photon and l=e, mu or tau. The soft and hard bremsstrahlung differential cross sections are computed for an arbitrary value of the photon energy threshold. We also study the O(alpha) QED corrections to the differential cross section with respect to the total combined energy of the recoil electron and a possible accompanying photon. Their difference from the corrections to the electron spectrum is investigated. We disc…
We discuss recent calculations of the O(alpha) QED corrections to the recoil electron energy spectrum in neutrino electron scattering, and to the spectrum of the combined energy of the recoil electron and a possible accompanying photon emitted in the scattering process. We then examine the role of these corrections in the interpretation of precise measurements from solar neutrino electron scattering experiments.
Control over quantum electrodynamics (QED) radiative corrections is critical for precise determination of neutrino oscillation probabilities from observed (anti)neutrino detection rates. It is particularly important to understand any difference between such corrections for different flavors of (anti)neutrinos in charged-current interactions. We provide theoretical foundations for calculating these corrections. Using effective field theory, the corrections are shown to factorize into soft, collinear, and hard functions. The soft and collinear functions contain large logarithms in perturbation t…
Using a real-time formalism of equilibrium and nonequilibrium quantum-field theory, we derive the reaction-rate formula for neutrino-conversion ($ν\to ν'$) process and $ν\barν'$ annihilation process, which take place in a hot and dense QED plasma with background (anti)neutrinos out of equilibrium. Also derived is the formula for the inverse processes to the above ones. Using the hard-thermal-loop resummation scheme, we include the contribution from the coherent processes. The decay/production of a neutrino causes an evolution of its spatial distribution. A scheme for dealing with this evolutio…
Interpretation of current and future neutrino oscillation and electron scattering experiments requires knowledge of lepton-nucleon and lepton-nucleus interactions at the percent level. We study the exchange of photons between charged particles and the nuclear medium for (anti)neutrino-, electron-, and muon-induced reactions inside a large nucleus. While quantum electrodynamics (QED)-medium contributions are formally suppressed by two powers of the electromagnetic coupling constant $α$ when compared to the leading-order cross sections, low-energy modes and the nuclear size enhance the effect by…
A scheme of quantum electrodynamic (QED) background-free radiative emission of neutrino pair (RENP) is proposed in order to achieve precision determination of neutrino properties so far not accessible. The important point for the background rejection is the fact that the dispersion relation between wave vector along propagating direction in wave guide (and in a photonic-crystal type fiber) and frequency is modified by a discretized non-vanishing effective mass. This effective mass acts as a cutoff of allowed frequencies, and one may select the RENP photon energy region free of all macro-cohere…
We study the equation of state of electron in strong magnetic fields which are greater than the critical value $B_c \simeq 4.4 \times 10^{13}$ Gauss. We find that such a strong magnetic field induces the anisotropic pressure of electron. We apply the result to the neutrino-driven wind in core-collapse supernovae and find that it can produce large entropy per baryon, $S \sim 400 k_B$. This mechanism might successfully account for the production of the heavy nuclei with mass numbers A = 80 -- 250 through the r-process nucleosynthesis.
Energy levels of a two-body atomic system in an external homogeneous magnetic field can be presented in terms of magnetic moments of their components, however, those magnetic moments being related to bound particles differ from their free values. Study of bound g factors in simple atomic systems are now of interest because of a recent progress in experiments on medium Z ions and of a new generation of muonium experiments possible with upcoming intensive muon sources. We consider bound corrections to the g factors in several atomic systems, experimental data for which are available in literatur…
We revisit several aspects of Standard Model physics at finite temperature that drive the theoretical value of the cosmological parameter $N_{\rm eff}$, the effective number of neutrinos in the early universe, away from 3. Our chief focus is finite-temperature corrections to the equation of state of the QED plasma in the vicinity of neutrino decoupling at $T \sim 1$ MeV, where $T$ is the photon temperature. Working in the instantaneous decoupling approximation, we recover at ${\cal O}(e^2)$, where $e$ is the elementary electric charge, the well-established correction of $δN_{\rm eff}^{(2)} \si…
The photon polarization operator in superstrong magnetic fields induces the dynamical photon "mass" which leads to screening of Coulomb potential at small distances $z\ll 1/m$, $m$ is the mass of an electron. We demonstrate that this behaviour is qualitatively different from the case of D=2 QED, where the same formula for a polarization operator leads to screening at large distances as well. Because of screening the ground state energy of the hydrogen atom at the magnetic fields $B \gg m^2/e^3$ has the finite value $E_0 = -me^4/2 \ln^2(1/e^6)$.
We present in this work a new calculation of the standard-model benchmark value for the effective number of neutrinos, $N_{\rm eff}^{\rm SM}$, that quantifies the cosmological neutrino-to-photon energy densities. The calculation takes into account neutrino flavour oscillations, finite-temperature effects in the quantum electrodynamics plasma to ${\cal O}(e^3)$, where $e$ is the elementary electric charge, and a full evaluation of the neutrino--neutrino collision integral. We provide furthermore a detailed assessment of the uncertainties in the benchmark $N_{\rm eff}^{\rm SM}$ value, through te…
The scattering of a neutrino on atomic electrons is considered in the situation where the energy transferred to the electrons is comparable to the characteristic atomic energies, as relevant to the current experimental search for neutrino magnetic moment. The process is contributed by the standard electroweak interaction as well as by the possible neutrino magnetic moment. Quantum mechanical sum rules are derived for the inclusive cross section at a fixed energy deposited in the atomic system, and it is shown that the differential over the energy transfer cross section is given, modulo very sm…
Neutrino oscillation experiments at accelerator energies aim to establish charge-parity violation in the neutrino sector by measuring the energy-dependent rate of $ν_e$ appearance and $ν_μ$ disappearance in a $ν_μ$ beam. These experiments can precisely measure $ν_μ$ cross sections at near detectors, but $ν_e$ cross sections are poorly constrained and require theoretical inputs. In particular, quantum electrodynamics radiative corrections are different for electrons and muons. These corrections are proportional to the small quantum electrodynamics coupling $α\approx 1/137$; however, the large s…
Comparing electronic Hydrogen with muonic Hydrogen shows that the discrepancy in measurement of the Lamb shift in the both systems are relatively of order of $(\frac{m_μ}{m_e})^{4-5}$. We explore the spectrum of Hydrogen atom in noncommutative $QED$ to compare the noncommutative effects on the both bound states. We show that in the Lorentz violating noncommutative QED the ratio of NC-corrections is $(\frac{m_μ}{m_e})^3$ while in the Lorentz conserving NCQED is $(\frac{m_μ}{m_e})^5$. An uncertainty about $1 \,Hz\ll 3\,kHz$ in the Lamb shift of Hydrogen atom leads to an NC correction about $10 \…
A classical calculation, modified by Compton-recoil kinematics, of the radiation emitted by a relativistic neutrino with mass and a magnetic moment passing through a transverse magnetic field. The calculation is performed in the neutrinos rest frame by the method of virtual quanta. The total number N of virtual quanta scattered by the neutrino is determined. The semi-classical result for the analog of the Klein-Nishina formula is compared with a QED calculation of the photon scattering cross section. The different angular distributions, both strongly peaked, lead to a factor of two difference …
The recent XENON1T excess can be explained by the solar active-sterile neutrino conversion with bound electrons via light mediator. Nevertheless, the atomic effects are usually omitted in the solar neutrino explanations. We systematically establish a second quantization formalism for both bound and ionized electrons to account for the atomic effects. This formalism is of great generality to incorporate various interactions for both neutrino and dark matter scatterings. Our calculation shows that the change in the cross section due to atomic effects can have important impact on the differential…
We discuss the experimental engineering of model systems for the description of QED in one spatial dimension via a mixture of bosonic $^{23}$Na and fermionic $^6$Li atoms. The local gauge symmetry is realized in an optical superlattice, using heteronuclear boson-fermion spin-changing interactions which preserve the total spin in every local collision. We consider a large number of bosons residing in the coherent state of a Bose-Einstein condensate on each link between the fermion lattice sites, such that the behavior of lattice QED in the continuum limit can be recovered. The discussion about …
A recent paper [M.B. Voloshin, Phys. Rev. Lett. 105, 201801 (2010)] pointed out that our earlier derivations of atomic ionization cross-section due to neutrino magnetic moments (arXiv:1001.2074v2) involved unjustified assumptions. We confirm and elaborate on this comment with these notes. We caution that the results of the sum-rule approach in this paper contradict the expected behaviour in atomic transitions.
The cosmic background neutrino of temperature 1.9 K affects rates of radiative emission of neutrino pair (RENP) from metastable excited atoms, since its presence blocks the pair emission by the Pauli exclusion principle. We quantitatively investigate how the Pauli blocking distorts the photon energy spectrum and calculate its sensitivity to cosmic parameters such as the neutrino temperature and its chemical potential. Important quantities for high sensitivities to these parameter measurement are found to be the level spacing of atomic de-excitation and the unknown mass value of lightest neutri…
A new scheme to determine the neutrino mass matrix is proposed using atomic de-excitation between two states of a few eV energy spacing. The determination of the smallest neutrino mass of the order of 1 meV and neutrino mass type, Majorana or Dirac, becomes possible, if one can coherently excite more than 1 gram of atoms using two lasers.
With the advent of detectors with sub-keV sensitivities, atomic ionization has been identified as a promising avenue to probe possible neutrino electromagnetic properties. The interaction cross-sections induced by millicharged neutrinos are evaluated with the ab-initio multi-configuration relativistic random-phase approximation. There is significant enhancement at atomic binding energies compared to that when the electrons are taken as free particles. Positive signals would distinctly manifest as peaks at specific energies with known intensity ratios. Selected reactor neutrino data with german…
An ab initio calculation of atomic ionization of germanium (Ge) by neutrinos was carried out in the framework of multiconfiguration relativistic random phase approximation. The main goal is to provide a more accurate cross section formula than the conventional one, which is based on the free electron approximation, for searches of neutrino magnetic moments with Ge detectors whose threshold is reaching down to the sub-keV regime. Limits derived with both methods are compared, using reactor neutrino data taken with low threshold germanium detectors.
We reexamine the role of electron binding effects in the inelastic neutrino-atom scattering induced by the neutrino magnetic moment. The differential cross section of the process is presented as a sum of the longitudinal and transverse components, according to whether the force that the neutrino magnetic moment exerts on electrons is parallel or perpendicular to momentum transfer. The atomic electrons are treated nonrelativistically. On this basis, the recent theoretical predictions concerning the magnetic neutrino-impact ionization of atoms are critically discussed. Numerical calculations are…
Matter effects on the mixing of the neutrinos mass eigenstates, also know as the Mikheyev-Smirnov-Wolfenstein effect, seem to be well established in describing the propagation of the neutrino from the source to detecting devices. These effects were mostly considered in bulk matter, but not inside the atoms. Here we consider the effect of the high electron densities existing in the atomic nuclei. We investigate if these effects can affect the known neutrino phenomenology. It was reported that the mixing of the neutrino in high density matter, such as inside a supernova, can affect the Majoron d…
The transition magnetic moment of a sterile-to-active neutrino conversion gives rise to not only radiative decay of a sterile neutrino, but also its non-standard interaction (NSI) with matter. For sterile neutrinos of keV-mass as dark matter candidates, their decay signals are actively searched for in cosmic X-ray spectra. In this work, we consider the NSI that leads to atomic ionization, which can be detected by direct dark matter experiments. It is found that this inelastic scattering process for a nonrelativistic sterile neutrino has a pronounced enhancement in the differential cross sectio…
We propose a simple unified description of two recent precision measurements which suggest new physics beyond the Standard Model of particle interactions, i.e. the deviation of $\sin^2 θ_W$ in deep inelastic neutrino-nucleon scattering and that of the anomalous magnetic moment of the muon. Our proposal is also consistent with a third precision measurement, i.e. that of parity nonconservation in atomic Cesium, which agrees with the Standard Model.
We consider theoretically ionization of an atom by neutrino impact taking into account electromagnetic interactions predicted for massive neutrinos by theories beyond the Standard Model. The effects of atomic recoil in this process are estimated using the one-electron and semiclassical approximations and are found to be unimportant unless the energy transfer is very close to the ionization threshold. We show that the energy scale where these effects become important is insignificant for current experiments searching for magnetic moments of reactor antineutrinos.
Studies of neutrino mixing and oscillations, solar neutrinos as background in dark matter searches involving electron detection, detection of sterile neutrino warm dark matter, and of possible electromagnetic properties of neutrinos, have generated interest in the low energy O(10 keV) scattering of electron neutrinos and antineutrinos by atomic electrons where the binding of the atomic electron cannot be ignored. Of particular interest is the ionization of atoms by neutrinos and antineutrinos. Most existing calculations are based on modifications of the free electron differential cross section…
Electron number densities in stars and the Earth are inhomogeneous because of atomic electrons. The large inhomogeneities on atomic-scale tend to form at tops of respective layers of stars, and 1s electrons of O locally produce weak potentials higher than that of the high MSW resonance. Then, supernova neutrinos experience vast numbers of non-adiabatic transitions. This inhomogeneous electron potential generates finite amplitudes of all three propagation eigenstates, and wave packets effectively separate. Then, spectral differences between three flavors significantly diminishes after propagati…
The exchange of two neutrinos at one loop leads to a long-range parity-violating force between fermions. We explore the two-neutrino force in the backdrop of atomic physics. We point out that this is the largest parity-violating long-range force in the Standard Model and calculate the effect of this force in experiments that probe atomic parity violation by measuring optical rotation of light as it passes through a sample of vaporized atoms. We perform explicit calculations for the hydrogen atom to demonstrate this effect. Although we find that the effect is too small to be observed in hydroge…
The exchange of a pair of low-mass neutrinos between electrons, protons and neutrons produces a "long-range" $1/r^5$ potential, which can be sought for in phenomena originating on the atomic and sub-atomic length scales. We calculate the effects of neutrino-pair exchange on transition and binding energies in atoms and nuclei. In the case of atomic s-wave states, there is a large enhancement of the induced energy shifts due to the lack of a centrifugal barrier and the highly singular nature of the neutrino-mediated potential. We derive limits on neutrino-mediated forces from measurements of the…
Ground-state hyperfine splittings in hydrogen and muonium are very well measured. Their difference, after correcting for magnetic moment and reduced mass effects, is due solely to proton structure--the large QED contributions for a pointlike nucleus essentially cancel. The rescaled hyperfine difference depends on the Zemach radius, a fundamental measure of the proton, computed as an integral over a product of electric and magnetic proton form factors. The determination of the Zemach radius, (1.043 +/- 0.016) fm, from atomic physics tightly constrains fits to accelerator measurements of proton …
Comment on "Possibility of superradiant neutrino emission by atomic condensate" by M. Blasone, L. Gastaldo and F. Romeo, Phys. Rev. D 113, 053010 (2026)
Massachusetts Institute of Technology（麻省理工学院）；MIT-Harvard Center for Ultracold Atoms（MIT-哈佛超冷原子中心）
We propose a scalable analog quantum simulator for quantum electrodynamics (QED) in two spatial dimensions. The setup for the U(1) lattice gauge field theory employs inter-species spin-changing collisions in an ultra-cold atomic mixture trapped in an optical lattice. Building on the previous one-dimensional implementation scheme of Ref. [1] we engineer spatial plaquette terms for magnetic fields, thus solving a major obstacle towards experimental realizations of realistic gauge theories in higher dimensions. We apply our approach to pure gauge theory and discuss how the phenomenon of confineme…
