arXiv subjects

A. Błaut

Publications and source records attributed to A. Błaut.

7 recordsLinked to original sources

arXiv2024

Recoil electron polarization-dependent T-odd correlations in neutrino elastic scattering on polarized electron target

Possible symmetry breaking tests with respect to the time inversion in the elastic scattering of neutrinos on polarized electrons are considered, assuming that the incoming neutrino beam is either longitudinally or transversely polarized, and both momentum and polarization of recoil electrons are observed. In the process, in addition to the standard interaction, the exotic scalar, pseudoscalar and tensor interactions can participate. Due to the nonstandard interactions, different types of triple T-odd products in the cross section may appear. We consider several experiments in which mixed products built of the recoil electron polarization and two other vector quantities (incoming neutrino momentum, its polarization, polarization of the electron target and outgoing electron momentum) can be identified. Observations of the T-odd correlations may indicate noninvariance under time reversal as well as the presence of exotic interactions. A complete analysis of the problem requires a precise determination of the possible contributions from the interactions mimicking the genuine violation of time reversal symmetry, e.g. final state interactions.

hep-ph↗

arXiv2020

Neutrino elastic scattering on polarized electrons as a tool for probing the neutrino nature

Possibility of using the polarized electron target (PET) for testing the neutrino nature is considered. One assumes that the incoming electron neutrino ($ν_e$) beam is the superposition of left chiral states with right chiral ones. Consequently the non-vanishing transversal components of $ν_e$ spin polarization may appear, both T-even and T-odd. $ν_e$s are produced by the low energy monochromatic (un)polarized emitter located at a near distance from the hypothetical detector which is able to measure both the azimuthal angle and polar angle of the recoil electrons, and/or also the energy of the outgoing electrons with a high resolution. A detection process is the elastic scattering of $ν_e$s (Dirac or Majorana) on the polarized electrons. Left chiral (LC) $ν_e$s interact mainly by the standard $V - A$ interaction, while right chiral (RC) ones participate only in the non-standard $V + A$, scalar $S_R$, pseudoscalar $P_R$ and tensor $T_R$ interactions. All the interactions are of flavour-conserving type (FC). We show that a distinction between the Dirac and the Majorana $ν_e$ s is possible both for the longitudinal and the transversal $ν_e$ polarizations. In the first case a departure from the standard prediction of the azimuthal asymmetry of recoil electrons is caused by the interferences between the non-standard complex S and T couplings. Such a deviation would indicate the Dirac $ν_e$ nature and the presence of time reversal symmetry violation (TRSV) interactions. In the second case the azimuthal asymmetries, polar distribution and energy spectrum of scattered electrons are sensitive to the interference terms between the standard and exotic interactions, proportional to the various angular correlations. Our model-independent study is carried out for the flavour $ν_e$ eigenstates in the relativistic $ν_e$ limit.

hep-ph↗

arXiv2017

On possibility of time reversal symmetry violation in neutrino elastic scattering on polarized electron target

In this paper, we indicate a possibility of utilizing the elastic scattering of the Dirac low energy ($\sim 1$ MeV) electron neutrinos ($ν_e$'s) on the polarized electron target (PET) in testing the time reversal symmetry violation (TRSV). We consider a scenario in which the incoming $ν_e$ beam is the superposition of left chiral (LC) and right chiral (RC) states. LC $ν_e$'s interact mainly by the standard $V - A$, while RC ones are only detected by the exotic $V + A$ and $S_R, P_R, T_R$ interactions. One assumes that the spin polarization vector of the initial $ν_e$'s is turned aside from the $ν_e$ momentum, and due to this the non-vanishing transversal component of the $ν_e$ spin polarization appears. We compute the differential cross section as a function of the recoil electron azimuthal angle and scattered electron energy, and show how the interference terms between standard $V-A$ and exotic $S_R, P_R, T_R$ couplings depend on the various angular correlations among the transversal $ν_e$ spin polarization, the polarization of the electron target, the incoming neutrino momentum and the outgoing electron momentum in the limit of relativistic $ν_e$. We illustrate how the maximal value of recoil electrons azimuthal asymmetry and the asymmetry axis location of outgoing electrons depend on the azimuthal angle of the transversal component of the $ν_e$ spin polarization, both for the time reversal symmetry conservation (TRSC) and TRSV. Next, we display that the electron energy spectrum and polar angle distribution of the recoil electrons are also sensitive to the interference terms between $V - A$ and $S_R, P_R, T_R$ couplings, proportional to the T-even and T-odd angular correlations. Our model-independent analysis is carried out for the flavor $ν_e$'s.

hep-ph↗

arXiv2016

Probing neutrino nature at Borexino detector with chromium neutrino source

In this paper, we indicate a possibility of utilizing the intense chromium source ($\sim 370 PBq$) in probing the neutrino nature in low energy neutrino experiments with the ultra-low threshold and background real-time Borexino detector located near the source ($\sim 8 m$). We analyze the elastic scattering of electron neutrinos (Dirac or Majorana, respectively) on the unpolarized electrons in the relativistic neutrino limit. We assume that the incoming neutrino beam is the superposition of left-right chiral states. Left chiral neutrinos may be detected by the standard $V A$ and non-standard scalar $S_L$, tensor $T_L$ interactions, while right chiral ones partake only in the exotic $V + A$ and $S_R, T_R$ interactions. Our model-independent study is carried out for the flavour (current) neutrino eigenstates. We compute the expected event number for the standard $V-A$ interaction of the left chiral neutrinos using the current experimental values of standard couplings and in the case of left-right chiral superposition. We show that the significant decrement in the event number due to the interference terms between the standard and exotic interactions for the Majorana $ν_e$'s may appear. The $90 \%$ C. L. sensitivity contours in the planes of corresponding exotic couplings are also found. The presence of interferences in the Majorana case gives the stronger constraints than for the Dirac neutrinos, even if the neutrino source is placed outside the detector.

hep-ph↗

arXiv2015

Azimuthal asymmetry of recoil electrons in neutrino-electron elastic scattering as signature of neutrino nature

In this paper, we show how a presence of the exotic scalar, tensor weak interactions in addition to the standard vector-axial (V-A) one may help to distinguish the Dirac from Majorana neutrinos in the elastic scattering of (anti)neutrino beam off the unpolarized electrons in the limit of vanishing (anti)neutrino mass. We assume that the incoming (anti)neutrino beam comes from the polarized muon decay at rest and is the left-right chiral mixture with assigned direction of the transversal spin polarization with respect to the production plane. We display that the azimuthal asymmetry in the angular distribution of recoil electrons is generated by the interference terms between the standard and exotic couplings, which are proportional to the transversal (anti)neutrino spin polarization and independent of the neutrino mass. This asymmetry for the Majorana neutrinos is distinct from the one for the Dirac neutrinos through the absence of interference between the standard and tensor couplings. Additionally, the interference term between the standard and scalar coupling of the only left chiral neutrinos, absent in the Dirac case, appears. We also indicate the possibility of utilizing the azimuthal asymmetry measurements to search for the new CP-violating phases. Our analysis is model-independent and consistent with the current upper limits on the non-standard couplings.

hep-ph↗

arXiv1997

Constraints and Solutions of Quantum Gravity in Metric Representation

We construct the regularised Wheeler-De Witt operator demanding that the algebra of constraints of quantum gravity is anomaly free. We find that for a subset of all wavefunctions being integrals of scalar densities this condition can be satisfied. We proceed to finding exact solutions of quantum gravity being of the form of functionals of volume and average curvature of compact three-manifold.

gr-qc↗

arXiv1996

Algebra of Constraints and Solutions of Quantum Gravity

We construct the regularized Wheeler--De Witt operator demanding that the algebra of constraints of quantum gravity is anomaly free. We find that for only a small subset of all wavefunctions being integrals of scalar densities this condition can be satisfied. It turns out that the resulting operator is much simpler than the one used in \cite{JK} to find exact solutions of Wheeler--De Witt equation. We proceed to finding exact solutions of quantum gravity and we discuss their interpretation making use of the quantum potential approach to quantum theory.

gr-qc↗