Recently, both ATLAS and CMS collaborations at the CERN Large Hadron Collider （LHC） announced their observations of an excess of diphoton events around the invariant mass of 750 GeV with a local significance of 3.6a...Recently, both ATLAS and CMS collaborations at the CERN Large Hadron Collider （LHC） announced their observations of an excess of diphoton events around the invariant mass of 750 GeV with a local significance of 3.6a and 2.6a, respectively. In this paper, we interpret the diphoton excess as the on-shell production of a real singlet scalar in the pp → S →γγchannel. To accommodate the observed production rate, we further introduce a vector-like fermion F, which carries both color and electric charges. The viable regions of model parameters are explored for this simple extension of the Standard Model （SM）. Moreover, we revisit the problem of electroweak vacuum stability in the same scenario, and find that the requirement for the electroweak vacuum stability up to high energy scales imposes serious constraints on the Yukawa coupling of the vector-like fermion and the quartic couplings of the SM Higgs boson and the new singlet scalar. Consequently, a successful explanation for the diphoton excess and the absolute stability of electroweak vacuum cannot be achieved simultaneously in this economical setup.展开更多
Conventional vacuum control in a milking system is accomplished by using a vacuum pump, sized for the maximum air flows into the milking system, running at a full speed. The difference between the pump capacity and th...Conventional vacuum control in a milking system is accomplished by using a vacuum pump, sized for the maximum air flows into the milking system, running at a full speed. The difference between the pump capacity and the necessary flow of air is compensated by allowing air to enter the system through a regulator. The solution presented in this paper uses a VFD （variable frequency driver） in order to drive the vacuum pump at a controlled speed, so that the air removed equals the air entering the milking system. The VFD technology is able to adjust the rate of air removal from the milking system, by changing the speed of the vacuum pump motor. The VFD is controlled by a computer using a virtual instrument in order to emulate a PID （proportion integration differentiation） regulator. The tests aimed to evaluate the vacuum regulator characteristics and vacuum stability. A statistical analysis of the experimental results was performed and it showed that there was a significant difference between the experimental results obtained for the two methods of vacuum regulation （with vacuum regulator and VFD controller respectively）. The experimental results proved that the used of the VFD controller led to a higher vacuum stability in terms of the error between the set vacuum value and the achieved values.展开更多
A new silica antireflective coating with improved hydrophobicity and optical stability in a vacuum is obtained by a two-step route. Firstly, silica sols are prepared with a sol-gel process, in which tetraethyl orthosi...A new silica antireflective coating with improved hydrophobicity and optical stability in a vacuum is obtained by a two-step route. Firstly, silica sols are prepared with a sol-gel process, in which tetraethyl orthosilicate is utilized as a precursor. And by introduction of fluorine containing glycol into the sols, the porosity of silica particles and surface polarity of the coatings are decreased. Afterward, coatings are constructed with low surface roughness by modification of PMBA-PMMA. The coatings retain transmission of up to 99.6%, and laser damage threshold of about 50 J/cm^2 at a wavelenth of 532 nm （1-on-1. 10 ns）展开更多
In this study,we investigate a two-component scalar dark matter framework featuring two singlet scalar fields as dark matter candidates.To ensure vacuum stability,we employ copositive criteria for the scalar potential...In this study,we investigate a two-component scalar dark matter framework featuring two singlet scalar fields as dark matter candidates.To ensure vacuum stability,we employ copositive criteria for the scalar potential.We analyze four distinct copositive scenarios characterized by specific negative parameter configurations using direct detection constraints.A comprehensive parameter space scan is performed under joint constraints from the observed dark matter relic density and direct detection experiments.The different signs of couplings not only correspond to different copositive criteria but also contribute to different parameter spaces caused by interference.The allowed values of quartic couplings are different for the four different cases;however,they all require the new Higgs to play a dominant role in determining dark matter relic density within the viable parameter space.展开更多
基金Supported by Innovation Program of the Institute of High Energy Physics(Y4515570U1)National Youth Thousand Talents ProgramCAS Center for Excellence in Particle Physics(CCEPP)
文摘Recently, both ATLAS and CMS collaborations at the CERN Large Hadron Collider （LHC） announced their observations of an excess of diphoton events around the invariant mass of 750 GeV with a local significance of 3.6a and 2.6a, respectively. In this paper, we interpret the diphoton excess as the on-shell production of a real singlet scalar in the pp → S →γγchannel. To accommodate the observed production rate, we further introduce a vector-like fermion F, which carries both color and electric charges. The viable regions of model parameters are explored for this simple extension of the Standard Model （SM）. Moreover, we revisit the problem of electroweak vacuum stability in the same scenario, and find that the requirement for the electroweak vacuum stability up to high energy scales imposes serious constraints on the Yukawa coupling of the vector-like fermion and the quartic couplings of the SM Higgs boson and the new singlet scalar. Consequently, a successful explanation for the diphoton excess and the absolute stability of electroweak vacuum cannot be achieved simultaneously in this economical setup.
文摘Conventional vacuum control in a milking system is accomplished by using a vacuum pump, sized for the maximum air flows into the milking system, running at a full speed. The difference between the pump capacity and the necessary flow of air is compensated by allowing air to enter the system through a regulator. The solution presented in this paper uses a VFD （variable frequency driver） in order to drive the vacuum pump at a controlled speed, so that the air removed equals the air entering the milking system. The VFD technology is able to adjust the rate of air removal from the milking system, by changing the speed of the vacuum pump motor. The VFD is controlled by a computer using a virtual instrument in order to emulate a PID （proportion integration differentiation） regulator. The tests aimed to evaluate the vacuum regulator characteristics and vacuum stability. A statistical analysis of the experimental results was performed and it showed that there was a significant difference between the experimental results obtained for the two methods of vacuum regulation （with vacuum regulator and VFD controller respectively）. The experimental results proved that the used of the VFD controller led to a higher vacuum stability in terms of the error between the set vacuum value and the achieved values.
基金supported by the National Major Project of Science and Technology under Grant No.2013ZX04006011-101
文摘A new silica antireflective coating with improved hydrophobicity and optical stability in a vacuum is obtained by a two-step route. Firstly, silica sols are prepared with a sol-gel process, in which tetraethyl orthosilicate is utilized as a precursor. And by introduction of fluorine containing glycol into the sols, the porosity of silica particles and surface polarity of the coatings are decreased. Afterward, coatings are constructed with low surface roughness by modification of PMBA-PMMA. The coatings retain transmission of up to 99.6%, and laser damage threshold of about 50 J/cm^2 at a wavelenth of 532 nm （1-on-1. 10 ns）
基金supported by the National Natural Science Foundation of China(12075043 and 12147205)supported by the National Natural Science Foundation of China(12447162)。
文摘In this study,we investigate a two-component scalar dark matter framework featuring two singlet scalar fields as dark matter candidates.To ensure vacuum stability,we employ copositive criteria for the scalar potential.We analyze four distinct copositive scenarios characterized by specific negative parameter configurations using direct detection constraints.A comprehensive parameter space scan is performed under joint constraints from the observed dark matter relic density and direct detection experiments.The different signs of couplings not only correspond to different copositive criteria but also contribute to different parameter spaces caused by interference.The allowed values of quartic couplings are different for the four different cases;however,they all require the new Higgs to play a dominant role in determining dark matter relic density within the viable parameter space.
