121260659
Open and hidden charm hadronic molecules
Properties of some open and hidden charm exotic states which have been studied using the composite model are summarized. It is found that, their decay properties are consistent with the data and further data are necessary to discriminate the hadronic molecular interpretation from other interpretations.
51032910
Strong and radiative decays of the D(s0)*(2317) meson in the DK-molecule picture
We consider a possible interpretation of the new charm-strange meson D* s0 (2317) as a hadronic molecule-a bound state of D and K mesons. Using an effective Lagrangian approach, we calculate the strong D* s0 → D s π 0 and radiative D* s0 → D* s γ decays. A new impact related to the DK molecular structure of the D* s0 (2317) meson is that the presence of u(d) quarks in the D and K mesons gives rise to a direct strong isospin-violating transition D* s0 → D s π 0 in addition to the decay mechanism induced by η - π 0 mixing considered previously. We show that the direct transition dominates over the 17 - π 0 mixing transition in the D* s0 → D s π 0 decay. Our results for the partial decay widths are consistent with previous calculations.
121889894
ORBITALLY EXCITED STATES OF QUARKONIA IN A NONRELATIVISTIC MODEL
Having succeeded in predicting the S wave spectra and decays of and mesons, Bhaghyesh, K. B. Vijaya Kumar and A. P. Monteiro, J. Phys. G: Nucl. Part. Phys.38, 085001 (2011), in this article, we apply our nonrelativistic quark model to calculate the spectra and decays of the orbitally excited states (P- and D-waves) of heavy quarkonia. The full potential used in our model consists of a Hulthen potential and a confining linear potential. The spin hyperfine, spin-orbit and tensor interactions are introduced to obtain the masses of the P- and D-wave states. The three-dimensional harmonic oscillator wave function is employed as a trial wave function to obtain the mass spectra. The model parameters and the wave function that reproduce the mass spectra of and mesons are used to investigate their decay properties. The two-photon decay widths, two-gluon decay widths and E1 radiative decay widths are calculated. The obtained values are compared with the experimental results and those obtained from other theoretical models.
27977343
Hidden local symmetry and chiral effective theory for vector and axial-vector mesons
Abstract.In this paper, we present the full Lagrangian of mesons (pseudoscalars, vectors and axial-vectors) to O(p4) by using the explicit global chiral symmetry and hidden local symmetry in the chiral limit. In this approach, we see that there are many other terms besides the usual eleven terms given in the literature from a hidden local symmetry approach. In particular, there are some terms in our full results which are important for understanding the vector meson dominance and $\pi$-$\pi$ scattering and providing consistent predictions on the decay rates of $a_1\rightarrow\gamma\pi$ and $a_1\rightarrow\rho\pi$ as well as for constructing a consistent effective chiral Lagrangian with chiral perturbation theory. It is likely that the structures of the effective chiral Lagrangian for O(p4) given in the literature by using hidden local symmetry are incomplete and consequently the resulting couplings are not reliable. We examine the issue that the more general effective chiral Lagrangian given in the present paper can provide more consistent predictions for the low energy phenomenology of the $\rho$-a1 system and result in more consistent descriptions on the low energy behavior of light flavor mesons.
119411933
Spin polarisability of the nucleon in the frame work of heavy quark effective field theory
We have constructed a heavy baryon effective field theory with photon as an external field in accordance with the symmetry requirements similar to the heavy quark effective field theory. By treating the heavy baryon and anti-baryon equally on the same footing in the effective field theory, we have calculated the spin polarisabilities $\gamma_i, i=1...4$ of the nucleon at third order and at fourth-order of the spin-dependent Compton scattering. At leading order (LO), our results agree with the corresponding results of the heavy baryon chiral perturbation theory, at the next-to-leading order(NLO) the results show a large correction to the ones in the heavy baryon chiral perturbation theory due to baryon-antibaryon coupling terms. The low energy theorem is satisfied both at LO and at NLO. The contributions arising from the heavy baryon-antibaryon vertex were found to be significant and the results of the polarisabilities obtained from our theory is much closer to the experimental data.
846321
ANOMALY AND ANOMALY-FREE TREATMENT OF QFT's BASED ON SYMMETRY-PRESERVING LOOP REGULARIZATION
The triangle anomaly in massless and massive QED is investigated by adopting the symmetry-preserving loop regularization method proposed recently in Refs. 1 and 2. The method is realized in the initial dimension of theory without modifying the original Lagrangian, it preserves symmetries under non-Abelian gauge and Poincare transformations in spite of the existence of two intrinsic mass scales Mc and μs which actually play the roles of UV- and IR-cutoff respectively. The axial-vector–vector-vector (AVV) triangle diagrams in massless and massive QED are evaluated explicitly by using the loop regularization. It is shown that when the momentum k of external state is soft with , m2 (m is the mass of loop fermions) and Mc → ∞, both massless and massive QED become anomaly free. The triangle anomaly is found to appear as quantum corrections in the case that m2, and Mc → ∞. Especially, it is justified that in the massless QED with μs = 0 and Mc → ∞, the triangle anomaly naturally exists as quantum effects in the axial-vector current when the ambiguity caused by the trace of gamma matrices with γ5 is eliminated by simply using the definition of γ5. It is explicitly demonstrated how the Ward identity anomaly of currents depends on the treatment for the trace of gamma matrices, which enables us to make a clarification whether the ambiguity of triangle anomaly is caused by the regularization scheme in the perturbation calculations or by the trace of gamma matrices with γ5. For comparison, an explicit calculation based on the Pauli–Villars regularization and dimensional regularization is carried out and the possible ambiguities of Ward identity anomalies caused from these two regularization schemes are carefully discussed, which include the ambiguities induced by the treatment of the trace of gamma matrices with γ5 and the action of the external momentum on the amplitude before the direct calculation of the AVV diagram.
123957691
Study on a Cellmap for the Reconstruction of Cosmic Ray Tracks in Drift Chamber
Taking L3 Cosmics experiment (L3 + C) as an example, we discussed a new Cellmap to reconstruct the hit in drift chamber of magnetic spectrometer for the very inclined comic-ray tracks, and compared the reconstruction results with the standard Cellmap of L3 + C. It shows that, for the very inclined cosmic-ray tracks, the new Cellmap can reconstruct more hits than the standard Cellmap, and the distribution of chi(2) of track reconstruction is also improved.
120406708
Analysis methods for results in gamma-ray astronomy
119606190
Quantization of the static space-time
A four-dimensional Lorentzian static space-time is equivalent to three-dimensional Euclidean gravity coupled to a massless Klein-Gordon field. By canonically quantizing the coupling model in the framework of loop quantum gravity, we obtain a quantum theory that actually describes quantized static space-times. The kinematical Hilbert space is the product of the Hilbert space of gravity with that of imaginary scalar fields. It turns out that the Hamiltonian constraint of the 2+1 model corresponds to a densely defined operator in the underlying Hilbert space, and hence it is finite without renormalization. As a new point of view, this quantized model might shed some light on a few physical problems concerning quantum gravity.
117504817
The X-ray spectra and XUV excess of some AGNs.
123323228
Test of Monte-Carlo model with the L3+C muon spectrum measurement
The paper shows good agreement between the atmospheric muon spectra measured by L3+C and the COMUGEN Monte-Carlo model. The atmospheric neutrino spectrum is inferred.