Propagation of high-energy neutrinos in a background of ultralight scalar dark matter

If high-energy neutrinos propagate in a background of ultralight scalar field particles of dark matter ($m_\varphi \sim 10^{-23}$eV), neutrino-dark matter interactions can play a role and affect the neutrino flux. In this work we analyse this effect using transport equations that account for the neutrino regeneration as well as absorption, and we consider the neutrino flux propagation in the extragalactic medium and also through the galactic halo of dark matter. We show the results for the final flux to arrive on Earth for different cases of point and diffuse neutrino fluxes. {We conclude that this type of neutrino interactions with ultralight scalar particles as dark matter can yield very different results in the neutrino flux and in the flavor ratios that can be measured in neutrino detectors such as IceCube.Comment: 11 pages, 11 figures, accepted for publication in Astroparticle Physic

Effective Majorana neutrino decay

We study the decay of heavy sterile Majorana neutrinos according to the interactions obtained from an effective general theory. We describe the two and three-body decays for a wide range of neutrino masses. The results obtained and presented in this work could be useful for the study of the production and detection of this particles in a variety of high energy physics experiments and astrophysical observations. We show in different figures the dominant branching ratios and the total decay width.Comment: 22 pages, 9 figures. arXiv admin note: text overlap with arXiv:1508.0158

Majorana neutrinos with effective interactions in B decays

We investigate the possible contribution of Majorana neutrinos to Bmeson decays in an effective interactionformalism, in the mass range 0.5GeV<mN<5GeV.We study the decay of the B meson via B−→μ−μ−π+at LHCb, which is a signal for leptonic number violationand the presence of Majorana neutrinos, and put bounds ondifferent new physics contributions, characterized by their Dirac- Lorentz structure. We also study the bounds imposedby the radiative B decay (B−→μ−νγ) results from Belle.The obtained bounds are more restrictive than previous values found for dimension 6 four-fermion contact vectorial andscalar Majorana neutrino interactions in the context of the left–right symmetric model for higher Majorana masses at the LHC, showing that the direct calculation of the effective N interactions contribution to different processes can help toput more stringent bounds to different UV-complete modelsparameterized by an effective Lagrangian

Majorana neutrinos production at LHeC in an effective approach

We investigate the possibility of detecting Majorana neutrinos at the Large Hadron-electron Collider (LHeC), an electron-proton collision mode at CERN. We study the $l_j^{+} + 3 jets$ ($l_j\equiv e ,\mu ,\tau$) final states which are, due to leptonic number violation, a clear signature for intermediate Majorana neutrino contributions. Such signals are not possible if the heavy neutrinos have Dirac nature. The interactions between Majorana neutrinos and the Standard Model (SM) particles are obtained from an effective lagrangian approach. We present our results for the total cross section as a function of the neutrino mass, the effective couplings and the new physics scale. We also show the discovery region as a function of the Majorana neutrino mass and the effective couplings. Our results show that the LHeC may be able to discover Majorana neutrinos with masses lower than $700$ GeV and $1300$ GeV for electron beams settings of $E_e=50$ GeV and $E_e=150$ GeV, respectively.Comment: 15 pages, 11 pdf figures. arXiv admin note: text overlap with arXiv:1110.095

Majorana Neutrinos Production at NLC in an Effective Approach

We investigate the possibility of detecting Majorana neutrinos at the $e^+e^-$ Next Linear Collider (NLC). We study the $l_j^{\mp} l_k^{\mp} + jets$ ($l_j\equiv e ,\mu ,\tau$) final states which are, due to leptonic number violation, a clear signature for intermediate Majorana neutrino contributions. Such signals (final leptons of the same-sign) are not possible if the heavy neutrinos have Dirac nature. The interactions between Majorana neutrinos and the Standard Model (SM) particles are obtained from an effective Lagrangian approach. As for the background, we considered the SM reaction $e^+ e^- \rightarrow W^+W^+W^-W^-$, with two $W^\prime$s decaying into jets and two $W^\prime$s decaying into $l^{\pm}+\nu(\bar \nu)$, producing extra light neutrinos which avoid the detection. We present our results for the total cross-section as a function of the neutrino mass and the center of mass energies. We also show the discovery region as a function of the Majorana neutrino mass and the effective coupling.Comment: 15 pages, 6 figures. Presentation improved, 1 reference and figures adde

Precession of neutrino-cooled accretion disks in gamma-ray burst engines

We study the precession of accretion disks in the context of gamma-ray burst inner engines. With an accretion disk model that allows for neutrino cooling, we evaluate the possible periods of disk precession and nutation due to the Lense-Thirring effect. Assuming jet ejection perpendicular to the disk midplane and a typical intrinsic time dependence for the burst, we find possible gamma-ray light curves with temporal microstructure similar to what is observed in some subsamples. We conclude that the precession and nutation of a neutrino-cooled accretion disk in the burst engine might be responsible for some events, especially those with a slow rise and a fast decay.Comment: 7 pages, 8 figures, accepted for publication in A&

Final taus and initial state polarization signatures from effective interactions of Majorana neutrinos at future

We study the possibility of future $$e^{+}e^{-}$$ colliders to disentangle different new physics contributions to the production of heavy sterile Majorana neutrinos in the lepton number violating channel $$e^{+}e^{-}\rightarrow l^{+} l^{+}+ 4 {\text {jets}}$$, with $$l=e, \mu , \tau$$. This is done investigating the final anti-tau polarization trails and initial beam polarization dependence of the signal on effective operators with distinct Dirac–Lorentz structure contributing to the Majorana neutrino production and decay, which parameterize new physics from a higher energy scale. We find that both analyses could well disentangle possible vectorial and scalar operators contributions

Angular and polarization observables for Majorana-mediated B decays with effective interactions

We probe the effective field theory extending the Standard Model with a sterile neutrino in B meson decays at B factories and lepton colliders, using angular and polarization observables. We put bounds on different effective operators characterized by their distinct Dirac–Lorentz structure, and probe the N-mediated B decays sensitivity to these interactions. We define a forward–backward asymmetry $$A_\mathrm{FB}^{\ell \gamma }$$ between the muon and photon directions for the $$B \rightarrow \mu \nu \gamma$$ decay, which allows us to separate the SM contribution from the effective lepton number conserving and violating processes, mediated by a near on-shell N. Using the most stringent constraints on the effective parameter space from Belle and BaBar we find that a measurement of the final polarization $$P_{\tau }$$ in the rare $$B^-\rightarrow \ell ^-_{1}\ell ^-_{2} \pi ^+$$ decays can help us infer the scalar or vector interaction content in the N production or decay vertices. We find that the B meson decays are more sensitive to scalar operators