Creation Of Neutrinos Research Articles

Neutrino signal from compact objects during their formation, their mergers, or as a signature of electric-charge phase transition

We study neutrino creation, propagation, and oscillations within an extremely magnetized background of finite-temperature nuclear matter and strange-quark matter (SQM). We focus on three particularly interesting cases and identify the astrophysical scenarios where such a signal may be found. The first case involves nuclear matter with electrons, and it is found during the central-engine stage of, both, short and long gamma-ray bursts (GRBs). Thus, for the short GRB case, it will also be associated with gravitational-wave events where there exist electromagnetic counterparts (e.g., GW170817). The second and third scenarios involve the presence of SQM. Accordingly, the second scenario occurs if SQM can become negatively charged (SQM−; which may only occur at high pressure) and, thus, it is embedded in a positron plasma. The third case may be found at the interphase where SQM transitions from positive (SQM+) to negative; here, positrons and electrons may constantly annihilate and give a distinctive neutrino signal. Therefore, this may also be a signature of the existence of strange stars. Given the wide range of magnetic fields we find in the literature, we also briefly discuss the maximum limit that a stellar-mass compact object may possess.

Chiral anomaly in SU(2)R-axion inflation and the new prediction for particle cosmology

Upon embedding the axion-inflation in the minimal left-right symmetric gauge extension of the SM with gauge group SU(2)L × SU(2)R × U(1)B−L, [1] proposed a new particle physics model for inflation. In this work, we present a more detailed analysis. As a compelling consequence, this setup provides a new mechanism for simultaneous baryogenesis and right-handed neutrino creation by the chiral anomaly of WR in inflation. The lightest right-handed neutrino is the dark matter candidate. This setup has two unknown fundamental scales, i.e., the scale of inflation and left-right symmetry breaking SU(2)R × U(1)B−L→ U(1)Y. Sufficient matter creation demands the left-right symmetry breaking scale happens shortly after the end of inflation. Interestingly, it prefers left-right symmetry breaking scales above 1010 GeV, which is in the range suggested by the non-supersymmetric SO(10) Grand Unified Theory with an intermediate left-right symmetry scale. Although WR gauge field generates equal amounts of right-handed baryons and leptons in inflation, i.e. B − L = 0, in the Standard Model sub-sector B − LSM ≠ 0. A key aspect of this setup is that SU(2)R sphalerons are never in equilibrium, and the primordial B − LSM is conserved by the Standard Model interactions. This setup yields a deep connection between CP violation in physics of inflation and matter creation (visible and dark); hence it can naturally explain the observed coincidences among cosmological parameters, i.e., ηB ≃ 0.3Pζ and ΩDM ≃ 5ΩB. The new mechanism does not rely on the largeness of the unconstrained CP-violating phases in the neutrino sector nor fine-tuned masses for the heaviest right-handed neutrinos. The SU(2)R-axion inflation comes with a cosmological smoking gun; chiral, non-Gaussian, and blue-tilted gravitational wave background, which can be probed by future CMB missions and laser interferometer detectors.

A cosmic collider: Was the IceCube neutrino generated in a precessing jet-jet interaction in TXS 0506+056?

Context. The neutrino event IceCube−170922A appears to originate from the BL Lac object TXS 0506+056. To understand the neutrino creation process and to localize the emission site, we studied the radio images of the jet at 15 GHz.Aims. Other BL Lac objects show properties similar to those of TXS 0506+056, such as multiwavelength variability or a curved jet. However, to date only TXS 0506+056 has been identified as neutrino emitter. The aim of this paper is to determine what makes the parsec-scale jet of TXS 0506+056 specific in this respect.Methods. We reanalyzed and remodeled 16 VLBA 15 GHz observations between 2009 and 2018. We thoroughly examined the jet kinematics and flux-density evolution of individual jet components during the time of enhanced neutrino activity between September 2014 and March 2015, and in particular before and after the neutrino event.Results. Our results suggest that the jet is very strongly curved and most likely observable under a special viewing angle of close to zero. We may observe the interaction between jet features that cross each other’s paths. We find subsequent flux-density flaring of six components passing the likely collision site. In addition, we find a strong indication for precession of the inner jet, and model a precession period of about 10 yr via the Lense-Thirring effect. We discuss an alternative scenario, which is the interpretation of observing the signature of two jets within TXS 0506+056, again hinting toward a collision of jetted material. We essentially suggest that the neutrino emission may result from the interaction of jetted material in combination with a special viewing angle and jet precession.Conclusions. We propose that the enhanced neutrino activity during the neutrino flare in 2014–2015 and the single EHE neutrino IceCube-170922A could have been generated by a cosmic collision within TXS 0506+056. Our findings seem capable of explaining the neutrino generation at the time of a low gamma-ray flux and also indicate that TXS 0506+056 might be an atypical blazar. It seems to be the first time that a potential collision of two jets on parsec scales has been reported and that the detection of a cosmic neutrino might be traced back to a cosmic jet-collision.

New Insight into Electronic Neutrino Creation under X-Ray Absorption by Water Tetrahedron Intercalated with Hydronium Ion (H3O+)

New Insight into Electronic Neutrino Creation under X-Ray Absorption by Water Tetrahedron Intercalated with Hydronium Ion (H3O+)

Neutrinos in IceCube from active galactic nuclei

Recently IceCube collaboration has reported first evidence for the astrophysical neutrinos. Observation corresponds to the total astrophysical neutrino flux of the order of $3 \cdot 10^{-8}$ $GeV/cm^2/s/sr$ in a PeV energy range. Active Galactic Nuclei (AGN) are natural candidate sources for such neutrinos. To model the neutrino creation in AGNs we study photopion production processes on the radiation field of the Shakura-Sunyaev accretion disks in the black hole vicinity. We show that this model can explain detected neutrino flux and avoids, at the same time, existing constraints from the gamma-ray and cosmic ray observations.

Creation of neutral fermions with anomalous magnetic moments from a vacuum by inhomogeneous magnetic fields

A consistent nonperturbative approach (based on QFT) to neutral fermion creation (due to their magnetic moments) in strong inhomogeneous magnetic fields is considered. It is demonstrated that quantization in terms of neutral particles and antiparticles is possible in terms of the states with well-defined spin polarization. Such states are localizable and can form wave packets in a given asymptotic region. In this case, the problem can be technically reduced to the problem of charged-particle creation by an electric step. In particular, the relation to the Schwinger method of an effective action is established. As an example, we calculate neutral fermion creation from the vacuum by a linearly growing magnetic field. We show that the total number and the vacuum-to-vacuum transition probability of created pairs depend only on the gradient of the magnetic field, but not on its strength, and this fact does not depend on the spacetime dimension. We show that the created flux aimed in one of the directions is formed from fluxes of particles and antiparticles of equal intensity and with the same magnetic moments parallel to the external field. In such a flux, particle and antiparticle velocities that are perpendicular to the plane of the magnetic moment and flux direction are essentially depressed. The creation of neutral fermions with anomalous magnetic moments leads to a smoothing of the initial magnetic field, which in turn prevents the appearance of superstrong constant magnetic fields. Our estimations show that the vacuum instability with respect to the creation of neutrinos and even neutrons in strong magnetic fields of the magnetars and fields generated during a supernova explosion has to be taken into account in the astrophysics. In particular, it may be of significance for dark matter studies.

Stochastic neutrino mixing mechanism

We propose a mechanism which provides an explanation of the Gallium and antineutrino reactor anomalies. Differently from original Pontecorvo's hypothesis, this mechanism is based on the phenomenological assumption in which the admixture of neutrino mass eigenstates in the moments of neutrino creation and detection can assume different configurations around the admixture parametrized by the usual values of the mixing angles $\theta_{12}$, $\theta_{23}$ and $\theta_{13}$. For simplicity, we assume a Gaussian distribution for the mixing angles in such a way that the average value of this distribution is given by the usual values of the mixing angles and the width of the Gaussian is denoted by $\alpha$. We show that the proposed mechanism provides a possible explanation for very short-baseline neutrino disappearance, necessary to accommodate Gallium and antineutrino reactor anomalies, which is not allowed in usual neutrino oscillations based on Pontecorvo's original hypotheses. We also can describe high-energy oscillation experiments, like LSND, Fermi and NuTeV, assuming a weakly energy dependent width parameter, $\alpha(E)$, that nicely fits all experimental results.

Perturbative neutrino pair creation by an external source

We consider the rate of fermion–antifermion pair creation by an external field. We derive a rate formula that is valid for a coupling with arbitrary vector and axial vector components to first order in perturbation theory. This is then applied to study the creation of neutrinos by nuclear matter, a problem with astrophysical relevance. We present an estimate for the creation rate per unit volume, compare this to previous results and comment on the role of the neutrino mass.

Leptogenesis and rescattering in supersymmetric models

The observed baryon asymmetry of the Universe can be due to the $B-L$ violating decay of heavy right handed (s)neutrinos. The amount of the asymmetry depends crucially on their number density. If the (s)neutrinos are generated thermally, in supersymmetric models there is limited parameter space leading to enough baryons. For this reason, several alternative mechanisms have been proposed. We discuss the nonperturbative production of sneutrino quanta by a direct coupling to the inflaton. This production dominates over the corresponding creation of neutrinos, and it can easily (i.e. even for a rather small inflaton-sneutrino coupling) lead to a sufficient baryon asymmetry. We then study the amplification of MSSM degrees of freedom, via their coupling to the sneutrinos, during the rescattering phase which follows the nonperturbative production. This process, which mainly influences the (MSSM) $D-$flat directions, is very efficient as long as the sneutrinos quanta are in the relativistic regime. The rapid amplification of the light degrees of freedom may potentially lead to a gravitino problem. We estimate the gravitino production by means of a perturbative calculation, discussing the regime in which we expect it to be reliable.

Numerical computation of solar neutrino flux attenuated by the MSW mechanism

We compute the survival probability of an electron neutrino in its flight through the solar core experiencing the Mikheyev-Smirnov-Wolfenstein effect with all three neutrino species considered. We adopted a hybrid method that uses an accurate approximation formula in the non-resonance region and numerical integration in the non-adiabatic resonance region. The key of our algorithm is to use the importance sampling method for sampling the neutrino creation energy and position and to find the optimum radii to start and stop numerical integration. We further developed a parallel algorithm for a message passing parallel computer. By using an idea of job token, we have developed a dynamical load balancing mechanism which is effective under any irregular load distributions

Space-time description of neutrino flavor oscillations

Recently the issue of EPR-like correlations in the mutual probability of detecting a neutrino together with an accompanying charged lepton has received a new impetus. In this paper we describe this effect using the propagators of the particles involved in Schwinger's parametric integral representation. We find this description more simple and more suitable to the purpose than the usual momentum-space analysis. We consider the cases of a monochromatic neutrino source, wave packet source, and neutrino creation in a localized space-time region. In the latter case we note that the space-time oscillation amplitude depends on the values of the neutrino masses, and becomes rather small for large relative mass differences (mass hierarchy). We obtain the expressions for the oscillation and coherence lengths in various circumstances. In the region of overlap our results confirm those of Dolgov et al.

Tagging direct neutrinos. A first step to neutrino tagging

As it is well known, high-energy neutrino investigations are performed by using neutrino beams from ~ and K decays ( 7 : ~ , K ~ ) , that is by letting the pions and the kaons decay over a large distance (the so-called decay length). The possibility of using tagged-neutrino beams in high-energy experiments must have occurred to many people. In tagged-neutrino experiments it should be required that the observed event due to the interaction of the neutrino in the neutrino detector would properly coincide in time with the act of neutrino creation (~--~v, K ~ , K ~ e w : .... ). Of course, in tagged-neutrino experiments the properties of neutrino beams (type, direction and energy) will be much better known than in the experiments performed so far. The main difficulty in designing such a facility is that the effective neutrino source (which is also the source of the charged particles to be detected in coincidence with the neutrino event) has a length equal to the decay length (of the order of hundreds of metres). In spite of the difficulties it seems that sooner or later such facilities will be available at various high-energy accelerators. Naturally such a (( maximum ~) programme would provide an extremely useful facility. Since the main difficulty in designing a tagged-neutrino facility is connected with the (large) scale of the decay length involved, let us turn our attention to such neutrino experiments, in which the decay length is deliberately shortened, that is to (( beam dump ~> experiments. In such experiments direct neutrinos are looked for, that is neutrinos which are neither produced in pion nor in kaon decays. In the present note I am suggesting a relatively simple device, a sort of (~ minimum ~ neutrino tagging programme, which could be put to work without very serious difficulties in beam dump experiments. Direct neutrino experiments have been proposed (L2) a long time ago and were even performed at a very low level of sensitivity (s). At the Neutrino-75 Conference