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.
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.
119236022
Estimates for X ( 4350 ) decays from the effective Lagrangian approach
The strong and electromagnetic decays of X(4350) with quantum numbers J{sup P}=0{sup ++} and 2{sup ++} have been studied by using the effective Lagrangian approach. The coupling constant between X(4350) and D{sub s}*D{sub s0}* is determined with the help of the compositeness condition which means that X(4350) is a bound state of D{sub s}*D{sub s0}*. Other coupling constants applied in the calculation are determined phenomenologically. Our numerical results show that, using the present data, the possibility that X(4350) is a D{sub s}*D{sub s0}* molecule cannot be ruled out within the present model.
118615785
Dense baryonic matter in conformally-compensated hidden local symmetry: Vector manifestation and chiral symmetry restoration
We find that, when the dilaton is implemented as a (pseudo-)Nambu-Goldstone boson using a conformal compensator or "conformon" in a hidden gauge symmetric Lagrangian written to $O(p^4)$ from which baryons arise as solitons, namely, skyrmions, the vector manifestation and chiral symmetry restoration at high density predicted in hidden local symmetry theory --- which is consistent with Brown-Rho scaling --- are lost or sent to infinite density. It is shown that they can be restored if in medium the behavior of the $\omega$ field is taken to deviate from that of the $\rho$ meson in such a way that the flavor $U(2)$ symmetry is strongly broken at increasing density. The hitherto unexposed crucial role of the $\omega$ meson in the structure of elementary baryon and multibaryon systems is uncovered in this work. In the state of half-skyrmions to which the skyrmions transform at a density $n_{1/2}^{} \gtrsim n_0^{}$ (where $n_0^{}$ is the normal nuclear matter density), characterized by the vanishing (space averaged) quark condensate but nonzero pion decay constant, the nucleon mass remains more or less constant at a value $\gtrsim$ 60 \% of the vacuum value indicating a large component of the nucleon mass that is not associated with the spontaneous breaking of chiral symmetry. We discuss its connection to the chiral-invariant mass $m_0^{}$ that figures in the parity-doublet baryon model.
119182734
Explicit derivation of the QED trace anomaly in symmetry-preserving loop regularization at one-loop level
The QED trace anomaly is calculated at one-loop level based on the loop regularization method which is realized in 4-dimensional space-time and preserves gauge symmetry and Poincare symmetry in spite of the introduction of two mass scales, namely, the ultraviolet (UV) cutoff M(c) and infrared (IR) cutoff mu(s). It is shown that the dilation Ward identity which relates the three-point diagrams with the vacuum polarization diagrams gets the standard form of trace anomaly through quantum corrections in taking the consistent limit M(c) -> 1 and mu(s) = 0 which recovers the original integrals. This explicitly demonstrates that the loop regularization method is indeed a self-consistent regularization scheme which is applicable to the calculations not only for the chiral anomaly but also for the trace anomaly, at least at one-loop level. It is also seen that the consistency conditions which relate the tensor-type and scalar-type irreducible loop integrals (ILIs) are crucial for obtaining a consistent result. As a comparison, we also present the one-loop calculations by using the usual Pauli-Villars regularization and the dimensional regularization.
14229719
The Classical geometry from a physical state in canonical quantum gravity
We construct a weave state which approximates a degenerate 3-metric of rank 2 at large scales. It turns out that a non-degenerate metric region can be evolved from this degenerate metric by the classical Ashtekar equations, hence the degeneracy of 3-metrics is not preserved by the evolution of Ashtekar's equations. As the s-knot state corresponding to this weave is shown to solve all the quantum constraints in loop quantum gravity, a physical state in canonical quantum gravity is related to the familiar classical geometry.
121855913
Possibility to Detect Upgoing Sleptons
Some supersymmetric models predict long lived charged sleptons. If they are exist, the τ ˜ , the supersymmetry partner of τ lepton, could be produced inside the earth by collisions of high energy neutrinos with nucleons. The possible signals of upgoing τ ˜ have been studied in various ways. Taking the atmospheric neutrino flux into account, the muon flux as main background is also estimated. By using the Waxman-Bahcall limit on the extraterrestrial neutrino flux, the resultant spectra show that there are about 70 events per year passing a km-scale underground experiment, such as ICECUBE.
12058058
Detectability of Upgoing Sleptons
Some supersymmetric models predicted long lived charged sleptons. Following Albuquerque, Burdman and Chacko \cite{albu}, we consider an exact process where the $ \widetilde{\tau}$, the supersymmetry partner of $\tau$ lepton, are produced inside the earth by collisions of high energy neutrinos with nucleons. We detailedly investigate the possible signals of upgoing $ \widetilde{\tau}$ by comparing with the background muons where atmospheric neutrino flux is taken into account. The realistic spectra shows that km-scale experiments could see as many as 69 events a year by using the Waxman-Bahcall limit on the extraterrestrial neutrino flux.
125881447
The neutrino mass and the periodicity of the neutrino burst from SN1987A
118365916
Geminga Pulsar in Cos-B and Heao-B Observations