2,059 research outputs found
Cancellation of divergences in unitary gauge calculation of process via one W loop, and application
Following the thread of R. Gastmans, S. L. Wu and T. T. Wu, the calculation
in the unitary gauge for the process via one W loop is
repeated, without the specific choice of the independent integrated loop
momentum at the beginning. We start from the 'original' definition of each
Feynman diagram, and show that the 4-momentum conservation and the Ward
identity of the W-W-photon vertex can guarantee the cancellation of all terms
among the Feynman diagrams which are to be integrated to give divergences
higher than logarithmic. The remaining terms are to the most logarithmically
divergent, hence is independent from the set of integrated loop momentum. This
way of doing calculation is applied to process via one W loop
in the unitary gauge, the divergences proportional to including
quadratic ones are all cancelled, and terms proportional to are
shown to be zero. The way of dealing with the quadratic divergences
proportional to in has subtle implication on the
employment on the Feynman rules especially when those rules can lead to high
level divergences. So calculation without integration on all the
functions until have to is a more proper or maybe necessary way of the
employment of the Feynman rules.Comment: 1 figure, 34 pages (updated
Terrace-like structure in the above-threshold ionization spectrum of an atom in an IR+XUV two-color laser field
Based on the frequency-domain theory, we investigate the above-threshold
ionization (ATI) process of an atom in a two-color laser field with infrared
(IR) and extreme ultraviolet (XUV) frequencies, where the photon energy of the
XUV laser is close to or larger than the atomic ionization threshold. By using
the channel analysis, we find that the two laser fields play different roles in
an ionization process, where the XUV laser determines the ionization
probability by the photon number that the atom absorbs from it, while the IR
laser accelerates the ionized electron and hence widens the electron kinetic
energy spectrum. As a result, the ATI spectrum presents a terrace-like
structure. By using the saddle-point approximation, we obtain a classical
formula which can predict the cutoff of each plateau in the terrace-like ATI
spectrum. Furthermore, we find that the difference of the heights between two
neighboring plateaus in the terrace-like structure of the ATI spectrum
increases as the frequency of the XUV laser increases
QACP: An Annotated Question Answering Dataset for Assisting Chinese Python Programming Learners
In online learning platforms, particularly in rapidly growing computer
programming courses, addressing the thousands of students' learning queries
requires considerable human cost. The creation of intelligent assistant large
language models (LLMs) tailored for programming education necessitates distinct
data support. However, in real application scenarios, the data resources for
training such LLMs are relatively scarce. Therefore, to address the data
scarcity in intelligent educational systems for programming, this paper
proposes a new Chinese question-and-answer dataset for Python learners. To
ensure the authenticity and reliability of the sources of the questions, we
collected questions from actual student questions and categorized them
according to various dimensions such as the type of questions and the type of
learners. This annotation principle is designed to enhance the effectiveness
and quality of online programming education, providing a solid data foundation
for developing the programming teaching assists (TA). Furthermore, we conducted
comprehensive evaluations of various LLMs proficient in processing and
generating Chinese content, highlighting the potential limitations of general
LLMs as intelligent teaching assistants in computer programming courses
Bis[2-(benzyliminomethyl)-4-chlorophenolato-κ2 N,O]nickel(II)
In the mononuclear centrosymmetric title compound, [Ni(C14H11ClNO)2], the NiII atom, lying on a center of symmetry, is four-coordinated by two O atoms and two N atoms from two Schiff base ligands, forming a slightly distorted square-planar environment. The dihedral angle between the two aromatic rings of the ligand is 72.0 (2)°. No significant hydrogen bonding or π–π stacking interactions are observed
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