1,822 research outputs found
The , decays in the perturbative QCD approach
Nonleptonic two body decays including radially excited or
mesons in the final state are studied using the perturbative QCD
approach based on factorization. The charmonium distribution amplitudes
are extracted from the Schrdinger states for the
harmonic oscillator potential. Utilizing these distribution amplitudes, we
calculate the numerical results of the
transition form factors and branching fractions of decays. The ratio between two decay modes and is compatible with the experimental
data within uncertainties, which indicate that the harmonic oscillator wave
functions for and work well. It is found that the
branching fraction of , which is dominated by the
twist-3 charmonium distribution amplitude, can reach the order of . We
hope it can be measured soon in the LHCb experiment.Comment: 9 pages, 3 figures,3 Table
Glue-on AdS holography for -deformed CFTs
The deformation is a solvable irrelevant deformation whose
properties depend on the sign of the deformation parameter . In
particular, -deformed CFTs with have been proposed to be
holographically dual to Einstein gravity where the metric satisfies Dirichlet
boundary conditions at a finite cutoff surface. In this paper, we put forward a
holographic proposal for -deformed CFTs with , in which case
the bulk geometry is constructed by gluing a patch of AdS to the original
spacetime. As evidence, we show that the trace flow equation, the
spectrum on the cylinder, and the partition function on the torus and the
sphere, among other results, can all be reproduced from bulk calculations in
glue-on AdS.Comment: 33 pages, 1 figure; v2: clarifications and references added, matches
published versio
Extremal surfaces in glue-on AdS/ holography
deformed CFTs with positive deformation parameter have been
proposed to be holographically dual to Einstein gravity in a glue-on
spacetime. The latter is constructed from AdS by gluing a
patch of an auxiliary AdS spacetime to its asymptotic boundary. In this
work, we propose a glue-on version of the Ryu-Takayanagi formula, which is
given by the signed area of an extremal surface. The extremal surface is
anchored at the endpoints of an interval on a cutoff surface in the glue-on
geometry. It consists of an RT surface lying in the AdS part of the
spacetime and its extension to the AdS region. The signed area is the
length of the RT surface minus the length of the segments in AdS. We find
that the Ryu-Takayanagi formula with the signed area reproduces the
entanglement entropy of a half interval for -deformed CFTs on the
sphere. We then study the properties of extremal surfaces on various glue-on
geometries, including Poincar\'e , global , and
the BTZ black hole. When anchored on multiple intervals at the boundary, the
signed area of the minimal surfaces undergoes phase transitions with novel
properties. In all of these examples, we find that the glue-on extremal
surfaces exhibit a minimum length related to the deformation parameter of
-deformed CFTs.Comment: 39 pages, 9 figures; v2: added references; v3: fixed typos, matches
published versio
Recent progress in migraine and cognitive disorder
Migraine is a chronic neurovascular disease characterized by recurrent unilateral headache, which induces incapacity. At present, there are many methods to evaluate cognitive function, and the cognitive function scale is commonly used. Recently, event-related potentials, resting state functional magnetic resonance imaging and other new technologies have been widely used to assess the cognitive function of migraine patients because of their high temporal resolution and high spatial resolution. In this paper, we can overview that the research progress of the relationship between migraine and methods of evaluate cognitive function
Production of Spin-Semiconducting Zigzag Graphene Nanoribbons by Constructing Asymmetric Notch on Graphene Edges
The electronic and magnetic properties of zigzag graphene nanoribbons with
asymmetric notches along their edges are investigated by first principle
density functional theory calculations. It is found that the electronic and
magnetic properties of the asymmetrically-notched graphene nanoribbons are
closely related with the depth of notches, but weekly dependent on the length
of notches. As the relative depth of notch increases, the energy level of
spin-up and spin-down becomes greatly shifted, associated with the gradual
increase of magnetic momentum. The asymmetric band shift allows the
asymmetrically notched graphene nanoribbons to be a spintronic semiconductor,
through which an N- or P-type spin-semiconductor can be obtained by doping B or
N atoms
(E)-4-Chloro-N-(2,4,6-trimethylÂbenzylÂidene)aniline
In the title compound, C16H16ClN, the dihedral angle between the benzene rings is 24.61 (13)°. In the crystal, only van der Waals interÂactions occur between neighbouring molÂecules
Endolymphatic sac tumor: case report and review of the literature
Endolymphatic sac tumor (ELST) is a rare neoplasm which can be encountered sporadically or in Von Hippel-Lindau (VHL) disease. Here we report a sporadic case of ELST in 31-year-old man. Neither the symptoms nor a family history of VHL disease were found in the patient. CT imaging demonstrated an expansile lytic lesion of the mastoid process of the left petrous bone. MR scanning revealed a 5.2 cm × 4.7 cm × 4.2 cm mass which showed hyperintensity on T1- and T2-weighted images. Histologic sections showed a papillary, cystic or glandular architecture. The papillary and glandular structures were lined by a single layer of flattened cuboidal-to-columnar cells. The stroma of the papillary fronds was richly vascularized and chronically inflamed. The tumor showed diffusely positive reactivity with cytokeratin (Pan), cytokeratin 19, cytokeratin 5/6, cytokeratin 7, EMA, vimentin, CD56, and NSE and also showed variable reactivity with glial fibrillary acidic protein (GFAP) and VEGF. The Ki-67 immunostain showed a proliferation index of < 1%. Because the mass was large, it was difficult to extirpate surgically. After surgery, the patient underwent gamma-knife radiosurgery for residual tumor. The findings indicate that ELST is a rare neoplasm with benign histopathological appearance and clinically destructive behavior. Because of the rarity of this tumor, it can easily be confused with other tumors such as paraganglioma, middle ear adenoma, adenocarcinoma, papillary carcinoma of thyroid or choroid plexus papilloma. Owing to its locally aggressive nature, it is difficult to extirpate surgically when it is large
Quantum sensing of temperature close to absolute zero in a Bose-Einstein condensate
We propose a theoretical scheme for quantum sensing of temperature close to
absolute zero in a quasi-one-dimensional Bose-Einstein condensate (BEC). In our
scheme, a single-atom impurity qubit is used as a temper-ature sensor. We
investigate the sensitivity of the single-atom sensor in estimating the
temperature of the BEC. We demonstrate that the sensitivity of the temperature
sensor can saturate the quantum Cramer-Rao bound by means of measuring quantum
coherence of the probe qubit. We study the temperature sensing performance by
the use of quantum signal-to-noise ratio (QSNR). It is indicated that there is
an optimal encoding time that the QSNR can reach its maximum in the
full-temperature regime. In particular, we find that the QSNR reaches a finite
upper bound in the weak coupling regime even when the temperature is close to
absolute zero, which implies that the sensing-error-divergence problem is
avoided in our scheme. Our work opens a way for quantum sensing of temperature
close to absolute zero in the BEC.Comment: 9 pages,9 figure
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