162 research outputs found
Role of interleukin-13 on the development of minimal change nephrotic syndrome - A novel animal model
Ph.DDOCTOR OF PHILOSOPH
Applications of Effective Theories of QCD in Collider Physics
In this thesis, we apply effective theories of Quantum Chromodynamics (QCD) in collider
physics.
First, we apply heavy quark effective theory (HQET) on the production asymmetries of
heavy hadrons in collider experiments. Asymmetries of the partial widths of a heavy hadron
and its antiparticle contain information about CP -violation. In collider experiments, Partial
widths are inevitably entangled with production rates. Therefore, understanding production
asymmetries is essential in extracting information about CP violation from collider experiments. At leading twist in perturbative QCD, such production asymmetries are absent. Using heavy quark effective theory (HQET), we examine the subleading-twist processes which
can produce the productions asymmetries. By fitting several non-perturbative parameters
to data, the production asymmetries of D+/D− measured at LHCb can be explained reasonably well. We also make predictions on production asymmetries of ΛQ/\bar ΛQ at the LHC. The asymmetries are found to be significant in the forward region and should be measurable
by LHCb. In addition, for further investigation in the future, we compute the partonic cross
sections for P waves.
Second, we apply soft-collinear effective theory (SCET) to resum large logarithms ln(1 −m^2_VH/\hat s ) in the threshold region m^2_VH → \hat s for the associated production of the Higgs boson with a vector boson at the LHC. The effect of NNNLL resummation on the total cross
section at NNLO is found to be negligible. For the distribution in τ = M^2_VH /s, the NNLL
resummation increases the fixed-order NLO result by ∼ 10% at τ ∼ 0.1, suggesting the
the importance of threshold resummation at τ of moderate size
Spin structure of heavy-quark hybrids
A unique feature of quantum chromodynamics (QCD), the theory of strong
interactions, is the possibility for gluonic degrees of freedom to participate
in the construction of physical hadrons, which are color singlets, in an
analogous manner to valence quarks. Hadrons with no valence quarks are called
glueballs, while hadrons where both gluons and valence quarks combine to form a
color singlet are called hybrids. The unambiguous identification of such states
among the experimental hadron spectrum has been thus far not possible.
Glueballs are particularly difficult to establish experimentally since the
lowest lying ones are expected to strongly mix with conventional mesons. On the
other hand, hybrids should be easier to single out because the set of quantum
numbers available to their lowest excitations may be exotic, i.e., not realized
in conventional quark-antiquark systems. Particularly promising for discovery
appear to be heavy hybrids, which are made of gluons and a
heavy-quark-antiquark pair (charm or bottom). In the heavy-quark sector
systematic tools can be used that are not available in the light-quark sector.
In this paper we use a nonrelativistic effective field theory to uncover for
the first time the full spin structure of heavy-quark hybrids up to
-terms in the heavy-quark-mass expansion. We show that such terms
display novel characteristics at variance with our consolidated experience on
the fine and hyperfine splittings in atomic, molecular and nuclear physics. We
determine the nonperturbative contributions to the matching coefficients of the
effective field theory by fitting our results to lattice-QCD determinations of
the charmonium hybrid spectrum and extrapolate the results to the bottomonium
hybrid sector where lattice-QCD determinations are still challenging.Comment: 10 pages, 3 figures. Updated version including the corrections in the
erratum of Journal version. Two additional operators included, figures and
analysis update
Large Separable Kernel Attention: Rethinking the Large Kernel Attention Design in CNN
Visual Attention Networks (VAN) with Large Kernel Attention (LKA) modules
have been shown to provide remarkable performance, that surpasses Vision
Transformers (ViTs), on a range of vision-based tasks. However, the depth-wise
convolutional layer in these LKA modules incurs a quadratic increase in the
computational and memory footprints with increasing convolutional kernel size.
To mitigate these problems and to enable the use of extremely large
convolutional kernels in the attention modules of VAN, we propose a family of
Large Separable Kernel Attention modules, termed LSKA. LSKA decomposes the 2D
convolutional kernel of the depth-wise convolutional layer into cascaded
horizontal and vertical 1-D kernels. In contrast to the standard LKA design,
the proposed decomposition enables the direct use of the depth-wise
convolutional layer with large kernels in the attention module, without
requiring any extra blocks. We demonstrate that the proposed LSKA module in VAN
can achieve comparable performance with the standard LKA module and incur lower
computational complexity and memory footprints. We also find that the proposed
LSKA design biases the VAN more toward the shape of the object than the texture
with increasing kernel size. Additionally, we benchmark the robustness of the
LKA and LSKA in VAN, ViTs, and the recent ConvNeXt on the five corrupted
versions of the ImageNet dataset that are largely unexplored in the previous
works. Our extensive experimental results show that the proposed LSKA module in
VAN provides a significant reduction in computational complexity and memory
footprints with increasing kernel size while outperforming ViTs, ConvNeXt, and
providing similar performance compared to the LKA module in VAN on object
recognition, object detection, semantic segmentation, and robustness tests
Development of teaching beliefs and the focus of change in the process of pre-service ESL teacher education
This study sets out to investigate how pre-serviceESLteachers shape their beliefs in the process of experimenting with new teaching methods introduced in the teacher education programme. A 4-year longitudinal study was conducted with four randomly selectedESLpre-service teachers. Their theoretical orientations ofESLinstruction were tracked at intervals through a protocol which consisted of i) descriptive accounts, ii) surveys, iii) lesson plan analysis, iv) lesson recording and v) interviews. Despite the fact that these 4 student teachers had shown different theoretical orientations in the protocols, they shared similar patterns of instructional practices in the Teaching Practicum. It was also found that the new teaching method practiced in the teacher education programme was re-conceptualised by these student teachers in the actual teaching context because of the strong influence of their personal agency beliefs
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