12,782 research outputs found
The Scotogenic Models for Dirac Neutrino Masses
We construct the one-loop and two-loop scotogenic models for Dirac neutrino
mass generation in the context of extensions of standard model. It
is indicated that the total number of intermediate fermion singlets is uniquely
fixed by anomaly free condition and the new particles may have exotic
charges so that the direct SM Yukawa mass term
and the Majorana mass term
are naturally forbidden. After the spontaneous
breaking of symmetry, the discrete or symmetry
appears as the residual symmetry and give rise to the stability of
intermediated fields as DM candidate. Phenomenological aspects of lepton flavor
violation, DM, leptogenesis and LHC signatures are discussed.Comment: 18 pages, 16 figure
Triggered massive and clustered stars formation by together H II regions G38.91-0.44 and G39.30-1.04
We present the radio continuum, infrared, and CO molecular observations of
infrared dark cloud (IRDC) G38.95-0.47 and its adjacent H II regions
G38.91-0.44 (N74), G38.93-0.39 (N75), and G39.30-1.04. The Purple Mountain
Observation (PMO) 13.7 m radio telescope was used to detect12CO J=1-0,13CO
J=1-0 and C18O J=1-0 lines. The carbon monoxide (CO) molecular observations can
ensure the real association between the ionized gas and the neutral material
observed nearby. To select young stellar objects (YSOs) associated this region,
we used the GLIMPSE I catalog. The13CO J=1-0 emission presents two large cloud
clumps. The clump consistent with IRDC G38.95-0.47 shows a triangle- like
shape, and has a steep integrated-intensity gradient toward H II regions
G38.91-0.44 and G39.30-1.04, suggesting that the two H II regions have expanded
into the IRDC. Four submillmeter continuum sources have been detected in the
IRDC G38.95-0.47. Only the G038.95-00.47-M1 source with a mass of 117 Msun has
outflow and infall motions, indicating a newly forming massive star. We
detected a new collimated outflow in the clump compressed by G38.93-0.39. The
derived ages of the three H II regions are 6.1*10^5yr, 2.5*10^5yr, and
9.0*10^5yr, respectively. In the IRDC G38.95-0.47, the significant enhancement
of several Class I YSOs indicates the presence of some recently formed stars.
Comparing the ages of these H II regions with YSOs (Class I sources and massive
G038.95-00.47-M1 source), we suggest that YSOs may be triggered by G38.91-0.44
and G39.30-1.04 together, which supports the radiatively driven implosion
model. It may be the first time that the triggered star formation has occurred
in the IRDC compressed by two H II regions. The new detected outflow may be
driven by a star cluster.Comment: 6 pages, 4 figures, Accepted for publication in A&
RANS Equations with Explicit Data-Driven Reynolds Stress Closure Can Be Ill-Conditioned
Reynolds-averaged Navier--Stokes (RANS) simulations with turbulence closure
models continue to play important roles in industrial flow simulations.
However, the commonly used linear eddy viscosity models are intrinsically
unable to handle flows with non-equilibrium turbulence. Reynolds stress models,
on the other hand, are plagued by their lack of robustness. Recent studies in
plane channel flows found that even substituting Reynolds stresses with errors
below 0.5% from direct numerical simulation (DNS) databases into RANS equations
leads to velocities with large errors (up to 35%). While such an observation
may have only marginal relevance to traditional Reynolds stress models, it is
disturbing for the recently emerging data-driven models that treat the Reynolds
stress as an explicit source term in the RANS equations, as it suggests that
the RANS equations with such models can be ill-conditioned. So far, a rigorous
analysis of the condition of such models is still lacking. As such, in this
work we propose a metric based on local condition number function for a priori
evaluation of the conditioning of the RANS equations. We further show that the
ill-conditioning cannot be explained by the global matrix condition number of
the discretized RANS equations. Comprehensive numerical tests are performed on
turbulent channel flows at various Reynolds numbers and additionally on two
complex flows, i.e., flow over periodic hills and flow in a square duct.
Results suggest that the proposed metric can adequately explain observations in
previous studies, i.e., deteriorated model conditioning with increasing
Reynolds number and better conditioning of the implicit treatment of Reynolds
stress compared to the explicit treatment. This metric can play critical roles
in the future development of data-driven turbulence models by enforcing the
conditioning as a requirement on these models.Comment: 35 pages, 18 figure
On the Drawbacks and Improvement of Legal System of Supervision on Securities Fraud in Cyberspace in China
The law of internet securities fraud mainly concerns internet safety, securities offering, information disclosure and securities trading on internet, the imperfections of which mainly include the low level for legislation, short of fundamental legislation, imperfect special legislation, conflicts among traditional legislation, and short of rules of international coordination. The discreet measures for perfection should include promoting legislation level, establishing relevant provisions for cyberspace conduct and special law such as Electronic Securities Trading Law, and amending Securities Law to regulate the prominent securities fraud in cyberspace. At present, it is urgent for securities regulator to establish and perfect the relevant supervision rules. Key words: Cyberspace; Securities Exchange; Securities Fraud; Legal SupervisionRésumé: La loi de la fraude en valeurs mobilières sur Internet concerne principalement la sécurité Internet, l’offres des titres, la divulgation de l'information et la transaction des titres sur internet, dont les imperfections incluent principalement un faible niveau de législation, une absence de législation fondamentale, une législation spéciale imparfaite, les conflits entre la législation traditionnelle, et une absence de règles de coordination internationale. Les mesures discrètes de la perfection devrait inclure la promotion du niveau de la législation, l’établissant des dispositions pertinentes pour la gestion de cyberespace et des lois spéciales telles que la Loi sur le commerce électronique des titres, et la modification de la Loi des titres pour réglementer la fraude en valeurs mobilières dans le cyberespace. À l'heure actuelle, il est urgent pour les régulateurs d'établir et de perfectionner les règles de surveillance appropriées.Mots-Clés: cyberspace; taxes de transaction; fraudes en valeurs mobilières; surveillane légal
- …