4,583 research outputs found
Resummation prediction on top quark transverse momentum distribution at large pT
We study the factorization and resummation of t-channel top quark transverse
momentum distribution at large pT in the SM at both the Tevatron and the LHC
with soft-collinear effective theory. The cross section in the threshold region
can be factorized into a convolution of hard, jet and soft functions. In
particular, we first calculate the NLO soft functions for this process, and
give a RG improved cross section by evolving the different functions to a
common scale. Our results show that the resummation effects increase the NLO
results by about 9%-13% and 4%-9% when the top quark pT is larger than 50 and
70 GeV at the Tevatron and the 8 TeV LHC, respectively. Also, we discuss the
scale independence of the cross section analytically, and show how to choose
the proper scales at which the perturbative expansion can converge fast.Comment: 32 pages, 10 figures, version published in Phys.Rev.
Protecting entanglement from correlated amplitude damping channel using weak measurement and quantum measurement reversal
Based on the quantum technique of weak measurement, we propose a scheme to
protect the entanglement from correlated amplitude damping decoherence. In
contrast to the results of memoryless amplitude damping channel, we show that
the memory effects play a significant role in the suppression of entanglement
sudden death and protection of entanglement under severe decoherence. Moreover,
we find that the initial entanglement could be drastically amplified by the
combination of weak measurement and quantum measurement reversal even under the
correlated amplitude damping channel. The underlying mechanism can be
attributed to the probabilistic nature of weak measurements.Comment: 11 pages, 5 figures, accepted by Quantum Information Processin
Triangle singularity in the decays
We study the reaction and
find that the mechanism to produce this decay develops a triangle singularity
around ~MeV. The differential width
shows a rapid growth around the
invariant mass being 1515~MeV as a consequence of the triangle singularity of
this mechanism, which is directly tied to the nature of the and
as dynamically generated resonances from the interaction of
pseudoscalar mesons. The branching ratios obtained for the decays are of the order of , accessible in
present facilities, and we argue that their observation should provide relevant
information concerning the nature of the low-lying scalar mesons.Comment: 12 pages, 8 figures, published in EPJ
The next-to-next-to-leading order soft function for top quark pair production
We present the first calculation of the next-to-next-to-leading order
threshold soft function for top quark pair production at hadron colliders, with
full velocity dependence of the massive top quarks. Our results are fully
analytic, and can be entirely written in terms of generalized polylogarithms.
The scale-dependence of our result coincides with the well-known two-loop
anomalous dimension matrix including the three-parton correlations, which at
the two-loop order only appear when more than one massive partons are involved
in the scattering process. In the boosted limit, our result exhibits the
expected factorization property of mass logarithms, which leads to a consistent
extraction of the soft fragmentation function. The next-to-next-to-leading
order soft function obtained in this paper is an important ingredient for
threshold resummation at the next-to-next-to-next-to-leading logarithmic
accuracy.Comment: 34 pages, 9 figures; v2: added references, matches the published
versio
Characterization of four-qubit states via Bell inequalities
A set of Bell inequalities classifying the quantum entanglement of four-qubit
states is presented. These inequalities involve only two measurement settings
per observer and can characterize fully separable, bi-separable and
tri-separable quantum states. In addition, a quadratic inequality of the Bell
operators for four-qubit systems is derived
Quantized Quasi-Two Dimensional Bose-Einstein Condensates with Spatially Modulated Nonlinearity
We investigate the localized nonlinear matter waves of the quasi-two
dimensional Bose-Einstein condensates with spatially modulated nonlinearity in
harmonic potential. It is shown that the whole Bose-Einstein condensates,
similar to the linear harmonic oscillator, can have an arbitrary number of
localized nonlinear matter waves with discrete energies, which are
mathematically exact orthogonal solutions of the Gross-Pitaevskii equation.
Their novel properties are determined by the principle quantum number n and
secondary quantum number l: the parity of the matter wave functions and the
corresponding energy levels depend only on n, and the numbers of density
packets for each quantum state depend on both n and l which describe the
topological properties of the atom packets. We also give an experimental
protocol to observe these novel phenomena in future experiments.Comment: 5 pages, 5 figure
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