118634638
Flavor transition mechanisms of propagating astrophysical neutrinos: A model independent parametrization
One of the important goals for future neutrino telescopes is to identify the flavors of astrophysical neutrinos and therefore determine the flavor ratio. The flavor ratio of astrophysical neutrinos observed on the Earth depends on both the initial flavor ratio at the source and flavor transitions taking place during propagations of these neutrinos. We propose a model independent parametrization for describing the above flavor transitions. A few flavor transition models are employed to test our parametrization. The observational test for flavor transition mechanisms through our parametrization is discussed.
118652336
Determination of the neutrino flavor ratio at the astrophysical source
We discuss the reconstruction of neutrino flavor ratios at astrophysical sources through the future neutrino-telescope measurements. Taking the ranges of neutrino mixing parameters ${\ensuremath{\theta}}_{ij}$ as those given by the current global fit, we demonstrate by a statistical method that the accuracies in the measurements of energy-independent ratios $R\ensuremath{\equiv}\ensuremath{\phi}({\ensuremath{\nu}}_{\ensuremath{\mu}})/(\ensuremath{\phi}({\ensuremath{\nu}}_{e})+\ensuremath{\phi}({\ensuremath{\nu}}_{\ensuremath{\tau}}))$ and $S\ensuremath{\equiv}\ensuremath{\phi}({\ensuremath{\nu}}_{e})/\ensuremath{\phi}({\ensuremath{\nu}}_{\ensuremath{\tau}})$ among integrated neutrino flux should both be better than 10% in order to distinguish between the pion source and the muon-damped source at the $3\ensuremath{\sigma}$ level. The 10% accuracy needed for measuring $R$ and $S$ requires an improved understanding of the background atmospheric neutrino flux to a better than 10% level in the future. We discuss the applicability of our analysis to practical situations that the diffuse astrophysical neutrino flux arises from different types of sources and each point source has a neutrino flavor ratio varying with energies. We also discuss the effect of the leptonic $CP$ phase on the flavor-ratio reconstruction.
13116555
Simulation of the cosmic ray tau neutrino telescope (CRTNT) experiment
A τ lepton can be produced in a charged current interaction by a cosmic ray tau neutrino with material inside a mountain. If it escapes from the mountain, it will decay and initiate a shower in the air, which can be detected by an air shower fluorescence/Cherenkov light detector. Designed according to such a principle, the cosmic ray tau neutrino telescope (CRTNT) experiment, located at the foothill of Mt Balikun in Xinjiang, China, will search for very high-energy cosmic τ neutrinos from energetic astrophysical sources by detecting those showers. This paper describes a Monte Carlo simulation for a detection of τ events by the CRTNT experiment. Ultra-high-energy cosmic ray events are also simulated to estimate the potential contamination. With the CRTNT experiment composed of four detector stations, each covering 64 ◦ × 14 ◦ field of view, the expected event rates are 28.6, 21.9 and 4.7 per year assuming an AGN neutrino flux according to Semikoz and Sigl (2004 J. Cosmol. Astropart. Phys. JCAP 04(2004)003), Mannheim–Protheroe–Rachen (MPR) active galactic nucleus (AGN) jet model and Stecker–Done–Salamon–Sommers (SDSS) AGN core model, respectively. Null detection of such a τ event by the CRTNT experiment in 1 year could set a 90% C.L. upper limit on 19.9 (eV cm −2 s −1 sr −1 ) for an E −2 neutrino spectrum.
6496614
Response of a 0.25 μm thin-film silicon-on-sapphire CMOS technology to total ionizing dose
The radiation response of a 0.25 μm silicon-on-sapphire CMOS technology is characterized at the transistor and circuit levels utilizing both standard and enclosed layout devices. The threshold-voltage shift is less than 170 mV and the leakage-current increase is less than 1 nA for individual standard-layout nMOSFET and pMOSFET devices at a total dose of 100 krad(SiO2). The increase in power supply current at the circuit level was less than 5%, consistent with the small change in off-state transistor leakage current. The technology exhibits good characteristics for use in the electronics of the ATLAS experiment at the Large Hadron Collider.
119074364
Post-ACME2013 CP-violation in Higgs Physics and Electroweak Baryogenesis
We present a class of cancellation mechanisms to suppress the total contributions of Barr-Zee diagrams to the electron electric dipole moment (eEDM). This class of mechanisms are of particular significance after the new eEDM upper limit, which strongly constrains the allowed magnitude of CP-violation in Higgs couplings and hence the feasibility of electroweak baryogenesis (EWBG), were released by the ACME collaboration in 2013. We point out: if both the CP-odd Higgs-photonphoton (Z boson) and the CP-odd Higgs-electron-positron couplings are turned on, a cancellation may occur either between the contributions of a CP-mixing Higgs boson, with the other Higgs bosons being decoupled, or between the contributions of a CP-even and a CP-odd Higgs bosons. With the assistance of the cancellation mechanisms, a large CP-phase in Higgs couplings with viable electroweak baryogenesis (EWBG) is still allowed. The reopened parameter regions would be probed by the future neutron, mercury EDM measurements, and direct measurements of Higgs CP-properties at the LHC and future colliders.
44596378
Unraveling the physics behind modified Higgs couplings: LHC versus a Higgs factory
Strongly modified $h\ensuremath{\gamma}\ensuremath{\gamma}$ and $hgg$ couplings indicate new electroweak and color mediators, respectively, with a light mass and a significant coupling to the Higgs boson. We point out the Higgs boson could have a significant decay width into the mediators. This represents one new class of exotic Higgs decay possibilities: off-shell exotic Higgs decays. We then propose uncovering the hidden new physics through such exotic decays. A great advantage of this strategy is that we can directly probe the couplings between the Higgs boson and the mediators, which is hard to achieve by using other methods. Focusing on the electroweak mediators, we study a simplified model using as an example final states with tau leptons and neutrinos. Because one of the mediators is off shell and its decay products are extremely soft, it is challenging to make a discovery at the Large Hadron Collider. A Higgs factory such as the International Linear Collider, however, could serve as a discovery machine for such exotic Higgs decays even in an early stage.
14074616
Classification of supersymmetric flux vacua in M-theory
Abstract We present a comprehensive classification of supersymmetric vacua of M-theory compactification on seven-dimensional manifolds with general four-form fluxes. We analyze the cases where the resulting four-dimensional vacua have N = 1 , 2 , 3 , 4 supersymmetry and the internal space allows for SU ( 2 ) , SU ( 3 ) or G 2 structures. In particular, we find for N = 2 supersymmetry, that the external space–time is Minkowski and the base manifold of the internal space is conformally Kahler for SU ( 2 ) structures, while for SU ( 3 ) structures the internal space has to be Einstein–Sasaki and no internal fluxes are allowed. Moreover, we provide a new vacuum with N = 1 supersymmetry and SU ( 3 ) structure, where all fluxes are non-zero and the first order differential equations are solved.
118430959
Quark angular momentum in a spectator model
Abstract We investigate the quark angular momentum in a model with the nucleon being a quark and a spectator. Both scalar and axial-vector spectators are included. We perform the calculations in the light-cone formalism where the parton concept is well defined. We calculate the quark helicity and canonical orbital angular momentum. Then we calculate the gravitational form factors which are often related to the kinetic angular momentums, and find that even in a no gauge field model we cannot identify the canonical angular momentums with half the sum of gravitational form factors. In addition, we examine the model relation between the orbital angular momentum and pretzelosity, and find it is violated in the axial-vector case.