33,984 research outputs found
Possibly New Charmed Baryon States from Decay
We examine the invariant mass spectrum of in decay measured by BABAR and find that through the 2-step processes of
, where denotes a
charmed baryon state, some of the peaks can be identified with the established
, and . Moreover, in
order to account for the measured spectrum, it is necessary to introduce a new
charmed baryon resonance with MeV.Comment: 8 pages, 1 figure, title changed and discussions updated, version
accepted for publication in Phys. Rev.
Learning Points and Routes to Recommend Trajectories
The problem of recommending tours to travellers is an important and broadly
studied area. Suggested solutions include various approaches of
points-of-interest (POI) recommendation and route planning. We consider the
task of recommending a sequence of POIs, that simultaneously uses information
about POIs and routes. Our approach unifies the treatment of various sources of
information by representing them as features in machine learning algorithms,
enabling us to learn from past behaviour. Information about POIs are used to
learn a POI ranking model that accounts for the start and end points of tours.
Data about previous trajectories are used for learning transition patterns
between POIs that enable us to recommend probable routes. In addition, a
probabilistic model is proposed to combine the results of POI ranking and the
POI to POI transitions. We propose a new F score on pairs of POIs that
capture the order of visits. Empirical results show that our approach improves
on recent methods, and demonstrate that combining points and routes enables
better trajectory recommendations
Study of Radiative Leptonic D Meson Decays
We study the radiative leptonic meson decays of D^+_{(s)}\to
\l^+\nu_{\l}\gamma (\l=e,\mu,\tau), and D^0\to
\l^+\l^-\gamma () within the light front quark model. In the standard
model, we find that the decay branching ratios of , and
are (), (), and
(), and that of D^0\to\l^+\l^-\gamma (\l=e,\mu) and
are and ,
respectively.Comment: 23 pages, 6 Figures, LaTex file, a reference added, to be published
in Mod. Phys. Lett.
Large normally hyperbolic cylinders in a priori stable Hamiltonian systems
We prove the existence of normally hyperbolic invariant cylinders in nearly
integrable hamiltonian systems
MINRES-QLP: a Krylov subspace method for indefinite or singular symmetric systems
CG, SYMMLQ, and MINRES are Krylov subspace methods for solving symmetric
systems of linear equations. When these methods are applied to an incompatible
system (that is, a singular symmetric least-squares problem), CG could break
down and SYMMLQ's solution could explode, while MINRES would give a
least-squares solution but not necessarily the minimum-length (pseudoinverse)
solution. This understanding motivates us to design a MINRES-like algorithm to
compute minimum-length solutions to singular symmetric systems.
MINRES uses QR factors of the tridiagonal matrix from the Lanczos process
(where R is upper-tridiagonal). MINRES-QLP uses a QLP decomposition (where
rotations on the right reduce R to lower-tridiagonal form). On ill-conditioned
systems (singular or not), MINRES-QLP can give more accurate solutions than
MINRES. We derive preconditioned MINRES-QLP, new stopping rules, and better
estimates of the solution and residual norms, the matrix norm, and the
condition number.Comment: 26 pages, 6 figure
Crystal growth and magnetic structure of MnBi2Te4
Millimeter-sized MnBiTe single crystals are grown out of Bi-Te flux
and characterized by measuring magnetic and transport properties, scanning
tunneling microscope (STM) and spectroscopy (STS). The magnetic structure of
MnBiTe below T is determined by powder and single crystal neutron
diffraction measurements. Below T=24\,K, Mn moments order
ferromagnetically in the \textit{ab} plane but antiferromagnetically along the
crystallographic \textit{c} axis. The ordered moment is 4.04(13) /Mn
at 10\,K and aligned along the crystallographic \textit{c}-axis. The electrical
resistivity drops upon cooling across T or when going across the
metamagnetic transition in increasing fields below T. A critical scattering
effect was observed in the vicinity of T in the temperature dependence of
thermal conductivity. However, A linear temperature dependence was observed for
thermopower in the temperature range 2K-300K without any anomaly around T.
These indicate that the magnetic order in Mn-Te layer has negligible effect on
the electronic band structure, which makes possible the realization of proposed
topological properties in MnBiTe after fine tuning of the electronic
band structure
Study of Decays in the Family Non-universal Models
In a combined investigation of the decays,
constraints on the related couplings in family non-universal
models are derived. We find that within the allowed parameter space, the
recently observed forward-backward asymmetry in the
decay can be explained, by flipping the signs of the Wilson coefficients
and . With the obtained constraints, we also calculate
the branching ratio of the decay. The upper bound of our
prediction is near the upper bound given by CDF Collaboration recently.Comment: 19 pages, 4 figures, some errors corrected; Journal versio
- …