Publications by authors named "Shaofeng Ge"

The origin of neutrino masses remains unknown. Both the vacuum mass and the dark mass generated by the neutrino interaction with dark matter (DM) particles or fields can fit the current oscillation data. The dark mass squared is proportional to the DM number density and, therefore, varies on the galactic scale with much larger values around the Galactic Center.

View Article and Find Full Text PDF
Article Synopsis
  • - The study discusses the first search for elastic scattering between low-mass dark matter particles (sub-MeV) and electrons, conducted using the PandaX-4T liquid xenon experiment.
  • - These sub-MeV dark matter particles can gain energy through interactions with cosmic-ray electrons, which could be spotted as electron recoil signals in the experiment.
  • - With an exposure of 0.63 tonne·year, the researchers established new limits on the interaction strength between dark matter and electrons across a range of masses from 10 eV/c² to 3 keV/c².
View Article and Find Full Text PDF

We report a search on sub-MeV fermionic dark matter absorbed by electrons with an outgoing active neutrino using the 0.63  tonne year exposure collected by the PandaX-4T liquid xenon experiment. No significant signals are observed over the expected background.

View Article and Find Full Text PDF

We report a novel search for the cosmic-ray boosted dark matter using the 100  tonne·day full dataset of the PandaX-II detector located at the China Jinping Underground Laboratory. With the extra energy gained from the cosmic rays, sub-GeV dark matter particles can produce visible recoil signals in the detector. The diurnal modulations in rate and energy spectrum are utilized to further enhance the signal sensitivity.

View Article and Find Full Text PDF

We point out a new type of diurnal effect for the cosmic ray boosted dark matter (DM). The DM-nucleon interactions not only allow the direct detection of DM with nuclear recoils but also allow cosmic rays to scatter with and boost the nonrelativistic DM to higher energies. If the DM-nuclei scattering cross sections are sufficiently large, the DM flux is attenuated as it propagates through the Earth, leading to a strong diurnal modulation.

View Article and Find Full Text PDF

The scalar nonstandard interactions (NSI) can also introduce matter effect for neutrino oscillation in a medium. Especially the recent Borexino data prefer nonzero scalar NSI, η_{ee}=-0.16.

View Article and Find Full Text PDF

Gluon-gluon to photon-photon scattering gg→γγ offers to the LHC experiments a uniquely powerful probe of dimension-8 operators in the standard model effective field theory that are quadratic in both the electromagnetic and gluonic field-strength tensors, such as would appear in the Born-Infeld extension of the standard model. We use 13-TeV ATLAS data on the production of isolated photon pairs to set lower limits on the scales of dimension-8 operators M≳1  TeV and discuss the prospective sensitivities of possible future hadron colliders.

View Article and Find Full Text PDF

Photodetection with extreme performances in terms of ultrafast response time, broad detection wavelength range, and high sensitivity has a wide range of optoelectronic and photonic applications, such as optical communications, interconnects, imaging, and remote sensing. Graphene, a typical two-dimensional Dirac semimetal, has shown excellent potential toward a high-performance photodetector with high operation speed, broadband response, and efficient carrier multiplications benefiting from its linear dispersion band structure with a high carrier mobility and zero bandgap. As the three-dimensional analogues of graphene, Dirac semimetal CdAs processes all advantages of graphene as a photosensitive material but potentially has stronger interaction with light as a bulk material and thus enhanced responsivity.

View Article and Find Full Text PDF

Positive quantum spin Hall gap in mono-layer 1T'-WTe2 is consistently supported by density-functional theory calculations, ultrafast pump-probe, and electrical transport measurements. It is argued that monolayer 1T'-WTe2 , which was predicted to be a semimetallic quantum spin Hall material, is likely a truly 2D quantum spin Hall insulator with a positive quantum spin Hall gap.

View Article and Find Full Text PDF

Black phosphorus has recently emerged as a promising material for high-performance electronic and optoelectronic device for its high mobility, tunable mid-infrared bandgap, and anisotropic electronic properties. Dynamical evolution of photoexcited carriers and the induced transient change of electronic properties are critical for materials' high-field performance but remain to be explored for black phosphorus. In this work, we perform angle-resolved transient reflection spectroscopy to study the dynamical evolution of anisotropic properties of black phosphorus under photoexcitation.

View Article and Find Full Text PDF

Coherent longitudinal acoustic phonon is generated and detected in multilayer Molybdenum Disulphide (MoS2) with number of layers ranging from 10 to over 1300 by femtosecond laser pulse. For thin MoS2, the excited phonon frequency exhibits a standing wave nature and shows linear dependence on the sample thickness. The frequency varies from 40 GHz to 0.

View Article and Find Full Text PDF

Limited control over charge recombination between photogenerated charge carriers largely hinders the progress in photocatalysis. Here, we introduce metal nanoparticles (Cr, Ag) to the surface of MoS2 nanosheets by simple synthetic means creating a hybrid metal-MoS2 nanosheet system with well-defined metal/semiconductor interfaces. We demonstrate that this hybrid nanosheet structure is capable of decoupling light absorption, primarily in MoS2, and carrier separation, across the metal-MoS2 heterostructure leading to drastic quenching of recombination between photogenerated carriers in MoS2, as proven by absorptance, photoluminescence, and ultrafast pump-probe spectroscopy.

View Article and Find Full Text PDF
Article Synopsis
  • * Monolayer samples display unique transient reflection signals compared to thicker forms, highlighting the importance of reduced dimensions on electron interactions.
  • * The valley polarization, which is critical for certain electronic properties, lasts only a few picoseconds before defects cause degradation, but the material maintains strong selectivity against disorder at the K point despite other areas showing rapid decline.
View Article and Find Full Text PDF

The residual Z(2)(s)(k) and Z(2)(s)(k) symmetries induce a direct and unique phenomenological relation with θx (≡ θ13) expressed in terms of the other two mixing angles θs(≡ θ12) and θa(≡ θ23) and the Dirac CP phase δD. Z(2)(s)(k) predicts a θx probability distribution centered around 3°-6° with an uncertainty of 2°-4°, while those from Z(2)(s)(k) are approximately a factor of 2 larger. Either result fits the T2K, MINOS, and Double Chooz measurements.

View Article and Find Full Text PDF

A PHP Error was encountered

Severity: Notice

Message: fwrite(): Write of 34 bytes failed with errno=28 No space left on device

Filename: drivers/Session_files_driver.php

Line Number: 272

Backtrace:

A PHP Error was encountered

Severity: Warning

Message: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: /var/lib/php/sessions)

Filename: Unknown

Line Number: 0

Backtrace: