19,516 research outputs found
Mass Dependence of Higgs Production at Large Transverse Momentum
The transverse momentum distribution of the Higgs at large is
complicated by its dependence on three important energy scales: , the top
quark mass , and the Higgs mass . A strategy for simplifying the
calculation of the cross section at large is to calculate only the
leading terms in its expansion in and/or . The
expansion of the cross section in inverse powers of is complicated by
logarithms of and by mass singularities. In this paper, we consider the
top-quark loop contribution to the subprocess at leading
order in . We show that the leading power of can be
expressed in the form of a factorization formula that separates the large scale
from the scale of the masses. All the dependence on and can
be factorized into a distribution amplitude for in the Higgs, a
distribution amplitude for in a real gluon, and an endpoint
contribution. The factorization formula can be used to simplify calculations of
the distribution at large to next-to-leading order in .Comment: 49 pages, 8 figure
Quantum walks on two kinds of two-dimensional models
In this paper, we numerically study quantum walks on two kinds of
two-dimensional graphs: cylindrical strip and Mobius strip. The two kinds of
graphs are typical two-dimensional topological graph. We study the crossing
property of quantum walks on these two models. Also, we study its dependence on
the initial state, size of the model. At the same time, we compare the quantum
walk and classical walk on these two models to discuss the difference of
quantum walk and classical walk
Homogenous Ensemble Phonotactic Language Recognition Based on SVM Supervector Reconstruction
Currently, acoustic spoken language recognition (SLR) and phonotactic SLR systems are widely used language recognition systems. To achieve better performance, researchers combine multiple subsystems with the results often much better than a single SLR system. Phonotactic SLR subsystems may vary in the acoustic features vectors or include multiple language-specific phone recognizers and different acoustic models. These methods achieve good performance but usually compute at high computational cost. In this paper, a new diversification for phonotactic language recognition systems is proposed using vector space models by support vector machine (SVM) supervector reconstruction (SSR). In this architecture, the subsystems share the same feature extraction, decoding, and N-gram counting preprocessing steps, but model in a different vector space by using the SSR algorithm without significant additional computation. We term this a homogeneous ensemble phonotactic language recognition (HEPLR) system. The system integrates three different SVM supervector reconstruction algorithms, including relative SVM supervector reconstruction, functional SVM supervector reconstruction, and perturbing SVM supervector reconstruction. All of the algorithms are incorporated using a linear discriminant analysis-maximum mutual information (LDA-MMI) backend for improving language recognition evaluation (LRE) accuracy. Evaluated on the National Institute of Standards and Technology (NIST) LRE 2009 task, the proposed HEPLR system achieves better performance than a baseline phone recognition-vector space modeling (PR-VSM) system with minimal extra computational cost. The performance of the HEPLR system yields 1.39%, 3.63%, and 14.79% equal error rate (EER), representing 6.06%, 10.15%, and 10.53% relative improvements over the baseline system, respectively, for the 30-, 10-, and 3-s test conditions
A Statistical Study of GRB X-ray Flares: Evidence of Ubiquitous Bulk Acceleration in the Emission Region
When emission in a conical relativistic jet ceases abruptly (or decays
sharply), the observed decay light curve is controlled by the high-latitude
"curvature effect". Recently, Uhm & Zhang found that the decay slopes of three
GRB X-ray flares are steeper than what the standard model predicts. This
requires bulk acceleration of the emission region, which is consistent with a
Poynting-flux-dominated outflow. In this paper, we systematically analyze a
sample of 85 bright X-ray flares detected in 63 Swift GRBs, and investigate the
relationship between the temporal decay index and spectral index
during the steep decay phase of these flares. The value
depends on the choice of the zero time point . We adopt two methods.
"Method I" takes as the first rising data point of each flare, and is
the most conservative approach. We find that at 99.9% condifence level 56/85
flares have decay slopes steeper than the simplest curvature effect prediction,
and therefore, are in the acceleration regime. "Method II" extrapolates the
rising light curve of each flare backwards until the flux density is three
orders of magnitude lower than the peak flux density, and defines the
corresponding time as the time zero point (t_0^II). We find that 74/85 flares
fall into the acceleration regime at 99.9% condifence level. This suggests that
bulk acceleration is common, may be even ubiquitous among X-ray flares,
pointing towards a Poynting-flux-dominated jet composition for these events.Comment: 68 pages, 6 figures, 2 tables, ApJS, in pres
- β¦