The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

Pasquale D. Serpico - One of the best experts on this subject based on the ideXlab platform.

  • EFFECTS OF NON-STANDARD NEUTRINO-ELECTRON INTERACTIONS ON RELIC NEUTRINO DECOUPLING
    Nuclear Physics, 2006
    Co-Authors: Gianpiero Mangano, Teguayco Pinto, Gennaro Miele, Sergio Pastor, Ofelia Pisanti, Pasquale D. Serpico
    Abstract:

    Abstract We consider the decoupling of neutrinos in the early Universe in presence of non-standard neutral current neutrino–electron interactions (NSI). We first discuss a semi-analytical approach to solve the relevant kinetic equations and then present the results of fully numerical and momentum-dependent calculations, including flavor neutrino oscillations. We present our results in terms of both the effective number of neutrino species ( N eff ) and the impact on the abundance of 4He produced during big bang nucleosynthesis. We find that the presence of neutrino–electron NSI may enhance the Entropy Transfer from electron–positron pairs into neutrinos instead of photons, up to a value of N eff ≃ 3.12 for NSI parameters within the ranges allowed by present laboratory data, which is almost three times the effect that appears for standard weak interactions. Thus non-standard neutrino–electron interactions do not essentially modify the density of relic neutrinos nor the bounds on neutrino properties from cosmological observables, such as their mass.

  • Effects of non-standard neutrino–electron interactions on relic neutrino decoupling
    Nuclear Physics B, 2006
    Co-Authors: Gianpiero Mangano, Teguayco Pinto, Gennaro Miele, Sergio Pastor, Ofelia Pisanti, Pasquale D. Serpico
    Abstract:

    We consider the decoupling of neutrinos in the early Universe in presence of non-standard neutral current neutrino-electron interactions (NSI). We first discuss a semi-analytical approach to solve the relevant kinetic equations and then present the results of fully numerical and momentum-dependent calculations, including flavor neutrino oscillations. We present our results in terms of both the effective number of neutrino species (Neff) and the impact on the abundance of He-4 produced during Big Bang Nucleosynthesis. We find that, for NSI parameters within the ranges allowed by present laboratory data, non-standard neutrino-electron interactions do not essentially modify the density of relic neutrinos nor the bounds on neutrino properties from cosmological observables, such as their mass. Nonetheless, the presence of neutrino-electron NSI may enhance the Entropy Transfer from electron-positron pairs into neutrinos instead of photons, up to a value of Neff=3.12. This is almost three times the correction to Neff=3 that appears for standard weak interactions

Motoki Nakata - One of the best experts on this subject based on the ideXlab platform.

  • Correlation between zonal flow shearing and Entropy Transfer rates in toroidal ion temperature gradient turbulence
    Physics of Plasmas, 2019
    Co-Authors: T. Miura, Tomo-hiko Watanabe, Shinya Maeyama, Motoki Nakata
    Abstract:

    The Transfer rate of the Entropy variable in the wavenumber space perpendicular to the equilibrium magnetic field is evaluated by means of the gyrokinetic simulations of the toroidal ion temperature gradient turbulence. Fluctuations of the perturbed gyrocenter distribution function of the linearly unstable mode are Transferred to those with higher radial wavenumbers through interactions with zonal flows driven by turbulence. The Entropy Transfer rate coincides with the zonal flow shearing rate in cases with weak ion temperature gradient where the zonal flows effectively regulate the turbulent transport. The obtained result verifies a correlation between the Entropy Transfer and the zonal flow shearing processes.The Transfer rate of the Entropy variable in the wavenumber space perpendicular to the equilibrium magnetic field is evaluated by means of the gyrokinetic simulations of the toroidal ion temperature gradient turbulence. Fluctuations of the perturbed gyrocenter distribution function of the linearly unstable mode are Transferred to those with higher radial wavenumbers through interactions with zonal flows driven by turbulence. The Entropy Transfer rate coincides with the zonal flow shearing rate in cases with weak ion temperature gradient where the zonal flows effectively regulate the turbulent transport. The obtained result verifies a correlation between the Entropy Transfer and the zonal flow shearing processes.

  • Exploring phase space turbulence in magnetic fusion plasmas
    Journal of Physics: Conference Series, 2014
    Co-Authors: Tomo-hiko Watanabe, M Nunami, Motoki Nakata, Hideo Sugama, Shinya Maeyama, Yasuhiro Idomura, Akihiro Ishizawa
    Abstract:

    Plasma turbulence accompanied with fluctuations of the distribution function and the electromagnetic fields develops on the phase space composed of the configuration space and the velocity space. Detailed structures of the distribution function in magnetic fusion plasmas are investigated by means of gyrokinetic simulations performed on massively parallel supercomputers. The gyrokinetic simulations of drift wave turbulence have demonstrated Entropy Transfer in the phase space, zonal flow enhancement by helical fields and the resultant transport reduction. The state-of-the-art high performance computing is utilized for a multi-scale turbulence simulation covering ion- and electron-scales and for a global-scale simulation of turbulent transport in a sub-ITER sized plasma.

  • Comparison between kinetic-ballooning-mode-driven turbulence and ion-temperature-gradient-driven turbulence
    Physics of Plasmas, 2014
    Co-Authors: Shinya Maeyama, Motoki Nakata, Tomo-hiko Watanabe, Akihiro Ishizawa, N. Miyato, Masatoshi Yagi, Yasuhiro Idomura
    Abstract:

    Electromagnetic turbulence driven by kinetic ballooning modes (KBMs) in high-β plasma is investigated based on the local gyrokinetic model. Analysis of turbulent fluxes, norms, and phases of fluctuations shows that KBM turbulence gives narrower spectra and smaller phase factors than those in ion-temperature-gradient (ITG)-driven turbulence. This leads to the smaller transport fluxes in KBM turbulence than those in ITG turbulence even when they have similar linear growth rates. From the analysis of the Entropy balance relation, it is found that the Entropy Transfer from ions to electrons through the field-particle interactions mainly drives electron perturbations, which creates radial twisted modes by rapid parallel motions of electrons in a sheared magnetic geometry. The nonlinear coupling between the dominant unstable mode and its twisted modes is important for the saturation of KBM turbulence, in contrast to the importance of zonal flow shearing in ITG turbulence. The coupling depends on the flux-tube domain with the one-poloidal-turn parallel length and on the torus periodicity constraint.

  • Gyrokinetic simulations of Entropy Transfer in high ion temperature LHD plasmas
    Plasma Physics and Controlled Fusion, 2012
    Co-Authors: Tomo-hiko Watanabe, M Nunami, Hideo Sugama, Kenji Tanaka, Motoki Nakata
    Abstract:

    Gyrokinetic simulations of the ion temperature gradient (ITG) turbulence in non-axisymmetric configurations modeled on the Large Helical Device (LHD) are performed with the Entropy Transfer analysis (Nakata et al 2012 Phys. Plasmas 19 022303). It is clarified that a fluctuation spectrum elongated in the radial wavenumber direction is formed in a neoclassically optimized field configuration with the inward-shifted magnetic axis position, where the zonal flows are more effectively generated than in the standard case. The strong interaction between zonal flows and turbulence causes the successive Entropy Transfer from low to high radial wavenumber space and the spectral broadening of ITG turbulence.

  • Gyrokinetic simulation studies for non-axisymmetric plasma confinement: turbulent transport and Entropy Transfer
    Journal of Physics: Conference Series, 2012
    Co-Authors: Tomo-hiko Watanabe, M Nunami, Hideo Sugama, Motoki Nakata
    Abstract:

    Turbulent ion heat transport and Entropy Transfer in non-axisymmetric toroidal plasma confinement are investigated by means of gyrokinetic simulations. Elongation of fluctuation spectrum into the radial wavenumber space is observed in the ion temperature gradient (ITG) turbulence simulation for a helical plasma configuration reconstructed from experimental data, and is examined by the Entropy Transfer function. For studying turbulence and zonal flows in a poloidally-rotating helical plasma, the conventional flux tube simulation model is extended to a bundle of flux tubes, where a multi-scale model of zonal flows and turbulence is formulated and tested by simulations of the linear ITG instability and the zonal flow response.

Gianpiero Mangano - One of the best experts on this subject based on the ideXlab platform.

  • EFFECTS OF NON-STANDARD NEUTRINO-ELECTRON INTERACTIONS ON RELIC NEUTRINO DECOUPLING
    Nuclear Physics, 2006
    Co-Authors: Gianpiero Mangano, Teguayco Pinto, Gennaro Miele, Sergio Pastor, Ofelia Pisanti, Pasquale D. Serpico
    Abstract:

    Abstract We consider the decoupling of neutrinos in the early Universe in presence of non-standard neutral current neutrino–electron interactions (NSI). We first discuss a semi-analytical approach to solve the relevant kinetic equations and then present the results of fully numerical and momentum-dependent calculations, including flavor neutrino oscillations. We present our results in terms of both the effective number of neutrino species ( N eff ) and the impact on the abundance of 4He produced during big bang nucleosynthesis. We find that the presence of neutrino–electron NSI may enhance the Entropy Transfer from electron–positron pairs into neutrinos instead of photons, up to a value of N eff ≃ 3.12 for NSI parameters within the ranges allowed by present laboratory data, which is almost three times the effect that appears for standard weak interactions. Thus non-standard neutrino–electron interactions do not essentially modify the density of relic neutrinos nor the bounds on neutrino properties from cosmological observables, such as their mass.

  • Effects of non-standard neutrino–electron interactions on relic neutrino decoupling
    Nuclear Physics B, 2006
    Co-Authors: Gianpiero Mangano, Teguayco Pinto, Gennaro Miele, Sergio Pastor, Ofelia Pisanti, Pasquale D. Serpico
    Abstract:

    We consider the decoupling of neutrinos in the early Universe in presence of non-standard neutral current neutrino-electron interactions (NSI). We first discuss a semi-analytical approach to solve the relevant kinetic equations and then present the results of fully numerical and momentum-dependent calculations, including flavor neutrino oscillations. We present our results in terms of both the effective number of neutrino species (Neff) and the impact on the abundance of He-4 produced during Big Bang Nucleosynthesis. We find that, for NSI parameters within the ranges allowed by present laboratory data, non-standard neutrino-electron interactions do not essentially modify the density of relic neutrinos nor the bounds on neutrino properties from cosmological observables, such as their mass. Nonetheless, the presence of neutrino-electron NSI may enhance the Entropy Transfer from electron-positron pairs into neutrinos instead of photons, up to a value of Neff=3.12. This is almost three times the correction to Neff=3 that appears for standard weak interactions

Katelin Schutz - One of the best experts on this subject based on the ideXlab platform.

  • A predictive mirror twin Higgs with small Z_2 breaking
    Journal of High Energy Physics, 2020
    Co-Authors: Keisuke Harigaya, Robert Mcgehee, Hitoshi Murayama, Katelin Schutz
    Abstract:

    The twin Higgs mechanism is a solution to the little hierarchy problem in which the top partner is neutral under the Standard Model (SM) gauge group. The simplest mirror twin Higgs (MTH) model — where a Z _2 symmetry copies each SM particle — has too many relativistic degrees of freedom to be consistent with cosmological observations. We demonstrate that MTH models can have an observationally viable cosmology if the twin mass spectrum leads to twin neutrino decoupling before the SM and twin QCD phase transitions. Our solution requires the twin photon to have a mass of ∼ 20 MeV and kinetically mix with the SM photon to mediate Entropy Transfer from the twin sector to the SM. This twin photon can be robustly discovered or excluded by future experiments. Additionally, the residual twin degrees of freedom present in the early Universe in this scenario would be detectable by future observations of the cosmic microwave background.

  • A Predictive Mirror Twin Higgs with Small $\mathbf{Z}_2$ Breaking
    Journal of High Energy Physics, 2020
    Co-Authors: Keisuke Harigaya, Robert Mcgehee, Hitoshi Murayama, Katelin Schutz
    Abstract:

    The twin Higgs mechanism is a solution to the little hierarchy problem in which the top partner is neutral under the Standard Model (SM) gauge group. The simplest mirror twin Higgs (MTH) model -- where a $\mathbf{Z}_2$ symmetry copies each SM particle -- has too many relativistic degrees of freedom to be consistent with cosmological observations. We demonstrate that MTH models can have an observationally viable cosmology if the twin mass spectrum leads to twin neutrino decoupling before the SM and twin QCD phase transitions. Our solution requires the twin photon to have a mass of $\sim 20$ MeV and kinetically mix with the SM photon to mediate Entropy Transfer from the twin sector to the SM. This twin photon can be robustly discovered or excluded by future experiments. Additionally, the residual twin degrees of freedom present in the early Universe in this scenario would be detectable by future observations of the cosmic microwave background.

  • Strongly interacting massive particles through the axion portal
    Physical Review D, 2018
    Co-Authors: Yonit Hochberg, Robert Mcgehee, Hitoshi Murayama, Eric Kuflik, Katelin Schutz
    Abstract:

    Author(s): Hochberg, Y; Kuflik, E; McGehee, R; Murayama, H; Schutz, K | Abstract: © 2018 authors. Published by the American Physical Society. Dark matter could be a thermal relic comprised of strongly interacting massive particles (SIMPs), where 3→2 interactions set the relic abundance. Such interactions generically arise in theories of chiral symmetry breaking via the Wess-Zumino-Witten term. In this work, we show that an axionlike particle can successfully maintain kinetic equilibrium between the dark matter and the visible sector, allowing the requisite Entropy Transfer that is crucial for SIMPs to be a cold dark matter candidate. Constraints on this scenario arise from beam dump and collider experiments, from the cosmic microwave background, and from supernovae. We find a viable parameter space when the axionlike particle is close in mass to the SIMP dark matter, with strong-scale masses of order a few hundred MeV. Many planned experiments are set to probe the parameter space in the near future.

Teguayco Pinto - One of the best experts on this subject based on the ideXlab platform.

  • Effects of non‐standard neutrino‐electron interactions in relic neutrino decoupling
    AIP Conference Proceedings, 2007
    Co-Authors: Teguayco Pinto
    Abstract:

    We consider the decoupling of neutrinos in the early Universe in presence of non‐standard neutral current neutrino‐electron interactions (NSI). We present the results of fully numerical and momentum‐dependent calculations, including flavor neutrino oscillations. We find that the presence of neutrino‐electron NSI may enhance the Entropy Transfer from electron‐positron pairs into neutrinos instead of photons, up to a value of the effective number of neutrinos Neff≃3.12 for NSI parameters within the ranges allowed by present laboratory data, which is almost three times the effect that appears for standard weak interactions. Thus non‐standard neutrino‐electron interactions do not essentially modify the density of relic neutrinos nor the bounds on neutrino properties from cosmological observables, such as their mass.

  • EFFECTS OF NON-STANDARD NEUTRINO-ELECTRON INTERACTIONS ON RELIC NEUTRINO DECOUPLING
    Nuclear Physics, 2006
    Co-Authors: Gianpiero Mangano, Teguayco Pinto, Gennaro Miele, Sergio Pastor, Ofelia Pisanti, Pasquale D. Serpico
    Abstract:

    Abstract We consider the decoupling of neutrinos in the early Universe in presence of non-standard neutral current neutrino–electron interactions (NSI). We first discuss a semi-analytical approach to solve the relevant kinetic equations and then present the results of fully numerical and momentum-dependent calculations, including flavor neutrino oscillations. We present our results in terms of both the effective number of neutrino species ( N eff ) and the impact on the abundance of 4He produced during big bang nucleosynthesis. We find that the presence of neutrino–electron NSI may enhance the Entropy Transfer from electron–positron pairs into neutrinos instead of photons, up to a value of N eff ≃ 3.12 for NSI parameters within the ranges allowed by present laboratory data, which is almost three times the effect that appears for standard weak interactions. Thus non-standard neutrino–electron interactions do not essentially modify the density of relic neutrinos nor the bounds on neutrino properties from cosmological observables, such as their mass.

  • Effects of non-standard neutrino–electron interactions on relic neutrino decoupling
    Nuclear Physics B, 2006
    Co-Authors: Gianpiero Mangano, Teguayco Pinto, Gennaro Miele, Sergio Pastor, Ofelia Pisanti, Pasquale D. Serpico
    Abstract:

    We consider the decoupling of neutrinos in the early Universe in presence of non-standard neutral current neutrino-electron interactions (NSI). We first discuss a semi-analytical approach to solve the relevant kinetic equations and then present the results of fully numerical and momentum-dependent calculations, including flavor neutrino oscillations. We present our results in terms of both the effective number of neutrino species (Neff) and the impact on the abundance of He-4 produced during Big Bang Nucleosynthesis. We find that, for NSI parameters within the ranges allowed by present laboratory data, non-standard neutrino-electron interactions do not essentially modify the density of relic neutrinos nor the bounds on neutrino properties from cosmological observables, such as their mass. Nonetheless, the presence of neutrino-electron NSI may enhance the Entropy Transfer from electron-positron pairs into neutrinos instead of photons, up to a value of Neff=3.12. This is almost three times the correction to Neff=3 that appears for standard weak interactions