621 research outputs found
Deep inelastic scattering near the endpoint in soft-collinear effective theory
We apply the soft-collinear effective theory (SCET) to deep inelastic
scattering near the endpoint region. The forward scattering amplitude, and the
structure functions are shown to factorize as a convolution of the Wilson
coefficients, the jet functions, the parton distribution functions. The
behavior of the parton distribution functions near the endpoint region is
considered. It turns out that it evolves with the Altarelli-Parisi kernel even
in the endpoint region, and the parton distribution function can be factorized
further into a collinear part and the soft Wilson line. The factorized form for
the structure functions is obtained by the two-step matching, and the radiative
corrections or the evolution for each factorized part can be computed in
perturbation theory. We present the radiative corrections of each factorized
part to leading order in alpha_s, including the zero-bin subtraction for the
collinear part.Comment: 40 pages, 12 figures. Two major changes: (1) The zero-bin subtraction
is included in the radiative corrections for the collinear part. (2) The
parton distribution function near the endpoint region is considered including
the soft part. Figures and references are added accordingl
Contribution of through the QCD anomaly in exclusive decays and
We compute the decay rates for the exclusive decays and in a QCD-improved factorization framework by including the
contribution from the process through
the QCD anomaly. This method provides an alternative estimate of the
contribution to these decays as
compared to the one using the intrinsic charm content of the
and mesons determined through the decays . The resulting branching ratios are compared with the CLEO
data on and
and predictions are made for the rest.Comment: 16 pages including 4 postscript figures; uses epsfig. The most recent
branching ratios from CLEO, ref. [5], are taken into account. The theory part
is unchange
Structure of divergences in Drell-Yan process with small transverse momentum
We consider the structure of divergences in Drell-Yan process with small
transverse momentum. The factorization proof is not trivial because various
kinds of divergences are intertwined in the collinear and soft parts at high
orders. We prescribe a method to disentangle the divergences in the framework
of the soft-collinear effective theory. The rapidity divergence is handled by
introducing the regulator in the collinear Wilson lines. The collinear
part, which consists of the transverse-momentum-dependent parton distribution
function (TMDPDF), is free of the rapidity divergence after the soft zero-bin
subtraction. There still remains the problem of mixing between the ultraviolet
and infrared divergences, which forbids the renormalization group description.
We show that the mixing is cancelled by the soft function. This suggests that
the collinear and soft parts should be treated as a whole in constructing a
consistent factorization theorem. The renormalization group behavior of the
combined collinear and soft parts is presented explicitly at one loop. We also
show that the integrated PDF can be obtained by integrating the TMDPDF over the
transverse momentum.Comment: 26 pages, 2 figures. Version published in PR
Nonfactorizable decay and QCD factorization
We study the unexpectedly large rate for the factorization-forbidden decay
within the QCD factorization approach. We use a non-zero
gluon mass to regularize the infrared divergences in vertex corrections. The
end-point singularities arising from spectator corrections are regularized and
carefully estimated by the off-shellness of quarks. We find that the
contributions arising from the vertex and leading-twist spectator corrections
are numerically small, and the twist-3 spectator contribution with chiral
enhancement and linear end-point singularity becomes dominant. With reasonable
choices for the parameters, the branching ratio for decay is
estimated to be in the range , which is compatible with
the Belle and BaBar data.Comment: Appendix added; it is emphasized that in the dominant twist-3
spectator corrections the end-point singularity contributions may be
estimated by the off-shellness of the charm quark (by the binding energy in
charmonium) and the gluon (by the transverse momentum of the light quark in
the kaon
Soft-Collinear Messengers: A New Mode in Soft-Collinear Effective Theory
It is argued that soft-collinear effective theory for processes involving
both soft and collinear partons, such as exclusive B-meson decays, should
include a new mode in addition to soft and collinear fields. These
"soft-collinear messengers" can interact with both soft and collinear particles
without taking them far off-shell. They thus can communicate between the soft
and collinear sectors of the theory. The relevance of the new mode is
demonstrated with an explicit example, and the formalism incorporating the
corresponding quark and gluon fields into the effective Lagrangian is
developed.Comment: 22 pages, 5 figures. Extended Section 6, clarifying the relevance of
different types of soft-collinear interaction
Soft Wilson lines in soft-collinear effective theory
The effects of the soft gluon emission in hard scattering processes at the
phase boundary are resummed in the soft-collinear effective theory (SCET). In
SCET, the soft gluon emission is decoupled from the energetic collinear part,
and is obtained by the vacuum expectation value of the soft Wilson-line
operator. The form of the soft Wilson lines is universal in deep inelastic
scattering, in the Drell-Yan process, in the jet production from e+e-
collisions, and in the gamma* gamma* -> pi0 process, but its analytic structure
is slightly different in each process. The anomalous dimensions of the soft
Wilson-line operators for these processes are computed along the light-like
path at leading order in SCET and to first order in alpha_s, and the
renormalization group behavior of the soft Wilson lines is discussed.Comment: 36 pages, 10 figures, 3 table
The Inclusive Semileptonic Decay Lepton Spectrum from
In this talk, we review the QCD calculation of the lepton spectrum from
inclusive semileptonic decay. We compare this prediction to that of the
ACCMM model. This latter work was done in collaboration with Csaba Csaki.Comment: MIT-CTP-2333, uses LATEX. Invited Talk, Presented at WHEPP-3 Workshop
in Madras,India, January, 199
Modeling of Spiking-Bursting Neural Behavior Using Two-Dimensional Map
A simple model that replicates the dynamics of spiking and spiking-bursting
activity of real biological neurons is proposed. The model is a two-dimensional
map which contains one fast and one slow variable. The mechanisms behind
generation of spikes, bursts of spikes, and restructuring of the map behavior
are explained using phase portrait analysis. The dynamics of two coupled maps
which model the behavior of two electrically coupled neurons is discussed.
Synchronization regimes for spiking and bursting activity of these maps are
studied as a function of coupling strength. It is demonstrated that the results
of this model are in agreement with the synchronization of chaotic
spiking-bursting behavior experimentally found in real biological neurons.Comment: 9 pages, 12 figure
Mekanisme Imbal Jasa Lingkungan Di Sub-das Cikapundung (Studi Kasus Pada Desa Cikole Dan Desa Suntenjaya Kabupaten Bandung Barat)
Mekanisme Imbal Jasa Lingkungan (IJL) merupakan salah satu upaya dalampengelolaan sub-DAS. Mekanisme ini telah diimplementasikan di sub-DAS Cikapundung.Kesepakatan program IJL di sub-DAS Cikapundung terjadi antara kelompok tani Giri PutriDesa Cikole dengan Pustanling dan kelompok tani Syurga Air dengan PT Aetra. BPLHDberperan sebagai mediator dalam kesepakatan ini. Pada pelaksanaannya, mekanisme IJL disub-DAS Cikapundung dikategorikan sebagai mekanisme IJL yang belum sepenuhnyamencerminkan mekanisme IJL yang berkelanjutan. Kriteria mekanisme IJL yangberkelanjutan seharusnya memenuhi aspek-aspek: realistic, voluntarily, conditional, danpro-poor (Munawir, 2009). Pada mekanisme IJL di sub-DAS Cikapundung hal ini belumsepenuhnya terjadi.Berdasarkan hal tersebut, penelitian ini bertujuan untuk merumuskan strategi yangdapat dilakukan agar mekanisme IJL di sub-DAS Cikapundung menjadi berkelanjutan.Metode yang digunakan pada penelitian ini adalah metode kualitatif. Pengumpulan datadilakukan melalui wawancara dan kuisioner dengan kelompok tani Syurga Air dan GiriPutri, PT Aetra, Pustanling, BPLHD, serta LP3ES. Analisis yang dilakukan adalah analisiskesenjangan, analisis peran faktor dan analisis SWOT. Mekanisme IJL di sub-DASCikapundung belum berjalan secara berkelanjutan dikarenakan masalah dalamkelembagaan dalam pengelolaan dan monitoring perkembangannya di lapangan. Selain itudana yang diberikan kepada kelompok tani juga masih tergolong belum mencukupi untukaktivitas konservasi lahan. Untuk mewujudkan mekanisme IJL yang berkelanjutan makadiperlukan upaya-upaya strategis terutama dalam kaitannya dengan kelembagaan mediasikesepakatan dengan pembentukan lembaga mediator mekanisme IJL yang bukan dariinstitusi pemerintah agar fasilitasi, advokasi dan koordinasi mekanisme IJL berjalan lebihoptimal, juga perlu dilakukan upaya untuk meningkatkan kepatuhan pada regulasi terkaitIJL, meningkatkan optimalisasi setiap forum pertemuan, meningkatkan kinerjastakeholders, serta melakukan negosiasi dengan potential buyer
Evaluation of the taste-masking effects of (2-hydroxypropyl)-β-cyclodextrin on ranitidine hydrochloride; a combined biosensor, spectroscopic and molecular modelling assessment
Taste assessment in an increasingly important aspect of formulation development, particularly for paediatric medications. Electronic taste sensing systems have the potential to offer a rapid, objective and safe method of taste assessment prior to the use of more costly human panels or animal models. In this study, the ability of the TS-5000Z taste sensing system to assess the taste masking efficiency of (2-hydroxypropyl)-β-cyclodextrin (HP-β-CyD) complexes with ranitidine hydrochloride was evaluated in order to explore the potential of the biosensor approach as a means of assessing taste masking by inclusion complexation. Nuclear magnetic resonance (NMR) spectroscopy and molecular docking studies were employed to identify and examine the interaction between ranitidine hydrochloride and HP-β-CyD. Taste-masking efficiencies were determined by the Euclidean distance between taste-masked formulations and the pure drug substance on a PCA score plot. The results showed that with increasing molarity of HP-β-CyD in the formulation, the distance from ranitidine hydrochloride increased, thus indicating a significant difference between the taste of the formulation and that of the pure drug. NMR studies also provided strong supporting evidence for the complexation between HP-β-CyD and ranitidine hydrochloride, with the H3′ region of the former identified as the most likely binding site for the drug. Molecular docking studies suggested that the dimethylamino and diamine groups of the drug form direct hydrogen bonds with the hydroxyl oxygen atoms of HP-β-CyD, while the furan ring docks in close proximity to H3′. This study has demonstrated that the biosensor system may provide quantitative data to assess bitterness of inclusion complexes with HP-β-CyD, while spectroscopic and modelling studies may provide a mechanistic explanation for the taste masking process. This in turn suggests that there is a role for biosensor approaches in providing early screening for taste masking using inclusion complexation and that the combination with mechanistic studies may provide insights into the molecular basis of taste and taste masking
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