116581806
Light axial-vector tetraquark state candidate: $a_1(1420)$
In this article, we study the axial-vector tetraquark state and two-quark-tetraquark mixed state consist of light quarks using the QCD sum rules. The present predictions disfavor assigning the $a_1(1420)$ as the axial-vector tetraquark state with $J^{PC}=1^{++}$, while support assigning the $a_1(1420)$ as the axial-vector two-quark-tetraquark mixed state.
118430852
Analysis of mass difference of the $\pi$ and $\rho$ with Bethe-Salpeter equation
In this article, we take into account the one-pion exchange force besides the onegluon exchange force to study the mass difference of the π and ρ mesons with the Bethe-Salpeter equation. After projecting the Bethe-Salpeter equation into an simple form, we can see explicitly that the bound energy |Eπ| ≫ |Eρ|. PACS number: 12.39.Ki, 12.39.Pn
15122700
Analysis of the Y(2175) as a tetraquark state with QCD sum rules
Abstract In this article, we take the point of view that Y ( 2175 ) be a tetraquark state which consists of color octet constituents, and calculate its mass and decay constant within the framework of the QCD sum rule approach. We release standard criterion in the QCD sum rules approach and take more phenomenological analysis, the value of the mass of Y ( 2175 ) is consistent with experimental data; there may be some tetraquark components in the state Y ( 2175 ) . If we retain standard criterion, larger mass than experimental data can be obtained, the current J μ ( x ) can interpolate a tetraquark state with larger mass, or Y ( 2175 ) has some components with larger mass. The dominating contribution comes from the perturbative term, which is in contrast to the sum rules with interpolating currents constructed from diquark pairs. The tetraquark states may consist of color octet constituents rather than diquark pairs.
118179000
Magnetic moment of the pentaquark state $\Theta^+(1540)$
In this article, we study the magnetic moment of the pentaquark $ \Theta^+(1540)$ as (scalar)diquark-(pseudoscalar)diquark-antiquark state with the QCD sum rules approach in the external electromagnetic field. Due to the special structure of the interpolating current, only the electromagnetic interactions of the $s$ quark with the external field have contributions to the magnetic moment with tensor structure $\{\sigma_{\mu\nu} {\hat p} +{\hat p}\sigma_{\mu\nu}\}$. The numerical results indicate the magnetic moment of the pentaquark state $ \Theta^+(1540)$ is about $\mu_{\Theta^+}=(0.16\pm0.03)\mu_N$.
119121085
ANALYSIS OF THE $B \to K^*_2(1430), a_2(1320), f_2(1270)$ FORM-FACTORS WITH LIGHT-CONE QCD SUM RULES
In this paper, we study the form-factors with the light-cone QCD sum rules, where the B-meson light-cone distribution amplitudes are used. In calculations, we observe that the line-shapes of the B-meson light-cone distribution amplitude ϕ+(ω) have significant impacts on the values of the form-factors, and expect to obtain severe constraints on the parameters of the B-meson light-cone distribution amplitudes from the experimental data in the future.
119252067
Next-to-leading Order Perturbative Contributions in the QCD Sum Rules for Mesonic Two-point Correlation Functions with Unequal Quark Masses
In this article, we assume that the two quarks have unequal masses and calculate the next-to-leading order contributions to the spectral densities of the mesonic two-point correlation functions of the vector, axialvector, scalar and pseudoscalar currents. We take dimensional regularization to regularize both the ultraviolet and infrared divergences, and use optical theorem to obtain the spectral densities directly, furthermore, we present some necessary technical details for readers convenience. The analytical expressions are applicable in many phenomenological analysis besides the QCD sum rules.
137717111
PROGRESS ON COUPLED RFQ-SFRFQ ACCELERATOR FOR MATERIALS IRRADIATION RESEARCH
There is always high interest to study material irradiation damage effects based on accelerators. The bombardment of solids with high energy particles causes some changes in many important engineering properties. A materials irradiation facility based on coupled RFQ-SFRFQ accelerator will be built in Peking University. The concept design and the structure optimization have been completed. The progress on the coupled RFQ-SFRFQ accelerator will be presented in this paper.
5667549
Large Misalignment between Stellar and Dust Bars in NGC 3488 Revealed by Spitzer and SDSS
A large position angle misalignment between the stellar and dust bars in the late-type barred spiral NGC 3488 was discovered, using mid-infrared images from the Spitzer Space Telescope and optical images from the Sloan Digital Sky Survey (SDSS). The angle between the two distinctive bar patterns was measured to be 25±2, larger than most of the misalignments found previously in barred systems based on Hα or H ii/CO observations. The stellar bar is bright at optical and 3.6μm, while the dust bar is more prominent in the 8μm band but also shows up in the SDSS u and g-band images, suggesting a rich interstellar medium environment harboring ongoing star formation. The angular misalignment between the two bars in NGC 3488 is unlikely to have been caused by spontaneous bar formation. We suggest that the two bars have different formation histories, and that the large misalignment was triggered by a tidal interaction with a small companion. A statistical analysis of a large sample of nearby galaxies with archival Spitzer data indicates that bar structure such as that seen in NGC 3488 is quite rare in the local Universe. Subject headings: galaxies: individual(NGC 3488) — galaxies: spiral — galaxies: structure — infrared: galaxies National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, P. R. China; caochen@bao.ac.cn, hwu@bao.ac.cn Graduate School, Chinese Academy of Sciences, Beijing 100039, China Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 College of Physical Sciences, Graduate School, Chinese Academy of Sciences, P.O. Box 3908, 100039 Beijing, China
59247128
Quantum field theory on quantized Bergman domain
We present an oscillator realization of discrete series representations of group SU(2, 2). We give formulas for the coherent state star-product quantization of a Bergman domain D. A formulation of a (regularized) noncommutative scalar field on a quantized D is given.
18719624
Warm Molecular Gas in Galaxy-Galaxy Merger NGC 6090
We present Submillimeter Array observations of the CO (2-1) and (3-2) transitions toward the merging galaxies of NGC 6090. The high-resolution CO data reveal three gas concentrations. The main component is peaking in the overlap region between the two galaxies, where the near-IR and radio continuum emission are weak. The CO (2-1) emission from the face-on galaxy NGC 6090E is somewhat stronger than that from the edge-on galaxy NGC 6090W. The CO (3-2) emission peaks in the overlap region, similar to the CO (2-1) emission. More than 50% of the CO (3-2) emission arises from the 2'' (1.2 kpc) area of the overlap region. There appears to be CO (3-2) emission toward the nuclear region and the northwest arm of NGC 6090E, while no CO (3-2) emission is detected toward NGC 6090W. Unlike the CO gas, most of the radio continuum emission comes from NGC 6090E. The strong CO emission, together with the weak radio continuum emission, suggests that star formation in the overlap region has not proceeded long enough to produce significant numbers of supernovae that would be detectable from their radio continuum emission.
279557
Topological quantum phase transitions and edge states in spin-orbital coupled Fermi gases
We study superconducting states in the presence of spin-orbital coupling and Zeeman field. It is found that a phase transition from a Fulde-Ferrell-Larkin-Ovchinnikov state to the topological superconducting state occurs upon increasing the spin-orbital coupling. The nature of this topological phase transition and its critical property are investigated numerically. Physical properties of the topological superconducting phase are also explored. Moreover, the local density of states is calculated, through which the topological feature may be tested experimentally.