相关论文: U(1) Problem Revisited
In this short paper, we argue that the chiral central charge $c_-$ of a (2+1)d topological ordered state is sometimes strongly constrained by 't Hooft anomaly of anti-unitary global symmetry. For example, if a (2+1)d fermionic TQFT has a…
A model based on an anomalous Abelian symmetry $U(1)_1\times U(1)_2$ is presented. This symmetry is responsible for both supersymmetry breaking and fermion mass generation. Quark and squark mass matrices are aligned to prevent large…
Spontaneously broken Abelian gauge symmetries can explain the fermion mass hierarchies of the minimal supersymmetric standard model. In most cases it is assumed that the $U(1)_H$ symmetry is anomalous. However, non-anomalous models are also…
The chiral anomaly is a quantum mechanical effect for massless Dirac fermions in both particle physics and condensed matter physics. Here we present a set of effective models for single massless Dirac fermions in one- and three-dimensions…
The chiral anomaly is a striking signature of quantum effects which lead to the non-conservation of a classically conserved current, specifically the chiral currents in systems of fermions. In condensed matter systems, the chiral anomaly…
Many of the distinctive and subtle features of the dynamics in the $U_A(1)$ channel in QCD can be related to gluon topology, more precisely to the topological susceptibility $\chi(k^2) = i\int d^4x~e^{ikx}< 0|T~Q(x)~Q(0)|0>$, where $Q =…
For all the success of the Standard Model (SM), it is on the verge of being surpassed. In this regard we argue, by showing a minimal flavor-structured model based on the non-Abelian discrete $SL_2(F_3)$ symmetry, that $U(1)$…
Using perturbation theory in the Euclidean (imaginary time) formalism as well as the non-perturbative Fujikawa method, we verify that the chiral anomaly equation remains unaffected in the presence of nonzero chemical potential, $\mu$. We…
The flavor singlet axial charge has been a source of study in the last years due to its relation to the so called {\it Proton Spin Problem}. The relevant flavor singlet axial current is anomalous, i.e., its divergence contains a piece which…
While quantum anomalies are often associated with the breaking of a classical symmetry in the quantum theory, their anomalous contributions to observables remain distinct and well-defined even when the symmetry is broken from the outset.…
There is evidence for existence of massless Dirac quasi-particles in graphene, which satisfy Dirac equation in (1+2) dimensions near the so called Dirac points which lie at the corners at the graphene's brilluoin zone. It is shown that…
We study flavor mixing and the axial anomaly in QCD at zero and finite temperature. Using the instanton liquid model, we show that the strength of the anomaly is essentially unchanged near the critical temperature for chiral symmetry…
We present a set of example models in which the Standard Model (SM) symmetry group is extended by a new abelian symmetry. This additional symmetry appears anomalous in the effective low-energy theory; however, the anomalies cancel out when…
The anomaly-anomaly correlator is studied using QCD sum rules. Using the matrix elements of anomaly between vacuum and pseudoscalars $\pi, eta$ and $\eta'$, the derivative of correlator $chi'(0)$ is evaluated and found to be $\approx 1.82…
This is the second in a series of two contributions in which we set out to establish a novel momentum space framework to treat field theoretical infinities in perturbative calculations when parity-violating objects occur. Since no analytic…
We give a perturbative proof that U(1) lattice gauge theories generate the axial anomaly in the continuum limit under very general conditions on the lattice Dirac operator. These conditions are locality, gauge covariance and the absense of…
We classify all the phenomenologically viable fermion mass matrices coming from a spontaneously broken abelian symmetry $ U(1)_X, $ with one and two additional chiral fields of opposite charges $ X=\pm 1. $ We find that the non-trivial…
We show that under the assumption of dynamical symmetry breaking of electro weak interactions by a top quark condensate, motivated by the Top Mode Standard Model, the top quark in this effective theory can be considered then as chiral color…
We consider theories with gauged chiral fermions in which there are abelian anomalies, and no nonabelian anomalies (but there may be nonabelian gauge fields present). We construct an associated theory that is gauge-invariant,…
We consider a theory with gauge group $G \times U(1)_A$ containing: i) an abelian factor for which the chiral matter content of the theory is anomalous $\sum_{f} q^f_A \neq 0 \neq \sum_{f} (q^f_A)^3$ ; ii) a nonanomalous factor $G$. In…