相关论文: The QCD beta-function at O(1/N_f)

There is a common belief that the main uncertainties in the theoretical analysis of neutrinoless double beta ($0\nu\beta\beta$) decay originate from the nuclear matrix elements. Here, we uncover another previously overlooked source of…

We compute the beta functions for the $O(N)^3$-invariant general sextic tensor model up to cubic order in the coupling constant, and at leading order in the $1/N$ expansion. Our method is a direct, explicit one, in the sense that we…

We calculate the beta function of non-linear sigma models with S^{D+1} and AdS_{D+1} target spaces in a 1/D expansion up to order 1/D^2 and to all orders in \alpha'. This beta function encodes partial information about the spacetime…

In this paper, we study the RG flow in the non-linear sigma models obtained from a 2d N=(0,2) supersymmetric QCD. The sigma model is parameterized by a single Kahler modulus. We determine its exact non-perturbative beta function using…

The positive zeros of [2|1], [1|2] and the most general possible [2|2] Pade approximants whose Maclaurin series reproduce the presently known terms in the three-flavour QCD beta-function are all shown to correspond to ultraviolet fixed…

We extend the phase diagram of SU(N) gauge-fermion theories as function of number of flavours and colours to the region in which asymptotic freedom is lost. We argue, using large $N_f$ results, for the existence of an ultraviolet…

We consider a non-Abelian gauge theory with $N_f$ fermions and discuss the possible existence of a non-trivial UV fixed point at large $N_f$. Specifically, we study the anomalous dimension of the (rescaled) glueball operator $\text{Tr}\…

We initiate a programme to compute curvature corrections to the nonabelian BI action. This is based on the calculation of derivative corrections to the abelian BI action, describing a maximal brane, to all orders in F. An exact calculation…

The general relation between the standard expansion coefficients and the beta function for the QCD coupling is exactly derived in a mathematically strict way. It is accordingly found that an infinite number of logarithmic terms are lost in…

The N component scalar tricritical theory is considered in a non-perturbative setting. We derive non-perturbative beta functions for the relevant couplings in $d\leq 3$. The beta functions are obtained through the use of an exact evolution…

The two-loop invariant (running) coupling of QCD is written in terms of the Lambert W function. The analyticity structure of the coupling in the complex Q^2-plane is established. The corresponding analytic coupling is reconstructed via a…

The results of approximate N$^$3LO and detailed NNLO fits to $xF_3$ data of the CCFR'97 collaboration are presented. We demonstrate that $1/Q^2$ non-perturbative corrections to $xF_3$ modeled by three independent procedures are shadowed by…

The renormalizability of the three dimensional supersymmetric CP^(N - 1) model is discussed in the 1/N-expansion method, to all orders of 1/N. The model has N copies of the dynamical field and the amplitudes are expanded in powers of 1/N.…

We compute the effective hamiltonian for non-leptonic |Delta F| = 1 decays in the standard model including next-to-next-to-leading order QCD corrections. In particular, we present the complete three-loop anomalous dimension matrix…

First results on the radiative corrections of order O(N_f\alpha_s\alpha) are presented for the off-shell production of W or Z bosons at the LHC, where N_f is the number of fermion flavours. These corrections comprise all diagrams at…

We have computed the four-loop contribution to the beta-function and to the anomalous dimension of the field for the two-dimensional lattice $N$-vector model. This allows the determination of the second perturbative correction to various…

We calculate the one loop beta functions for nonlinear sigma models in four dimensions containing general two and four derivative terms. In the O(N) model there are four such terms and nontrivial fixed points exist for all N \geq 4. In the…

Using the higher covariant derivatives regularization of gauge theories in the framework of the background field method, supplemented with one-loop Pauli-Villars regulator fields, we obtain a version of the renormalization group equation…

To investigate the non-perturbative, electric sector of a deconfined gauge theory at nonzero temperature, we consider a SU(2) matrix model. We compute beta-functions to one loop order for the simplest extension of the O(4) nonlinear sigma…

Instability in the scalar channel of the fermion-antifermion scattering amplitude in massless QED_3 for number of flavours less than the critical value 128/3\pi^2 is demonstrated. The anomalous dimensions of gauge-invariant composite…