Search results for "High Energy Physics - Lattice"
showing 10 items of 466 documents
Gluon mass through ghost synergy
2011
In this work we compute, at the "one-loop-dressed" level, the nonperturbative contribution of the ghost loops to the self-energy of the gluon propagator, in the Landau gauge. This is accomplished within the PT-BFM formalism, which guarantees the gauge-invariance of the emerging answer. In particular, the contribution of the ghost-loops is automatically transverse, by virtue of the QED-like Ward identities satisfied in this framework. Using as nonperturbative input the available lattice data for the ghost dressing function, we show that the ghost contributions have a rather sizable effect on the overall shape of the gluon propagator, both for $d=3,4$. Then, by exploiting a recently introduce…
Supersymmetric Extension of Technicolor & Fermion Mass Generation
2012
We provide a complete extension of Minimal Walking Technicolor able to account for the standard model fermion masses. The model is supersymmetric at energies greater or equal to the technicolor compositeness scale. We integrate out, at the supersymmetry breaking scale, the elementary Higgses. We use the resulting four-fermion operators to derive the low energy effective theory. We then determine the associated tree-level vacuum and low energy spectrum properties. Furthermore we investigate the phenomenological viability of the model by comparing its predictions with electroweak precision tests and experimental bounds on the mass spectrum. We then turn to the composite Higgs phenomenology at…
Anomalous tensor magnetic moments and form factors of the proton in the self-consistent chiral quark-soliton model
2010
We investigate the form factors of the chiral-odd nucleon matrix element of the tensor current. In particular, we aim at the anomalous tensor magnetic form factors of the nucleon within the framework of the SU(3) and SU(2) chiral quark-soliton model. We consider $1/N_c$ rotational corrections and linear effects of SU(3) symmetry breaking with the symmetry-conserving quantization employed. We first obtain the results of the anomalous tensor magnetic moments for the up and down quarks: $\kappa_{T}^{u}=3.56$ and $\kappa_{T}^{d}=1.83$, respectively. The strange anomalous tensor magnetic moment is yielded to be $\kappa_{T}^{s}=0.2\sim -0.2$, that is compatible with zero. We also calculate the co…
Chiral corrections to the 1 −+ exotic meson mass
2016
We first construct the effective chiral Lagrangians for the $1^{-+}$ exotic mesons. With the infrared regularization scheme, we derive the one-loop infrared singular chiral corrections to the $\pi_1(1600)$ mass explicitly. We investigate the variation of the different chiral corrections with the pion mass under two schemes. Hopefully, the explicit non-analytical chiral structures will be helpful to the chiral extrapolation of the lattice data from the dynamical lattice QCD simulation of either the exotic light hybrid meson or tetraquark state.
Precise determination of resonance pole parameters through Pad\'e approximants
2014
In this work, we present a precise and model--independent method to extract resonance pole parameters from phase-shift scattering data. These parameters are defined from the associated poles in the second Riemann sheet, unfolded by the analytic continuation to the complex pole using Pad\'e approximants. Precise theoretical parameterizations of pion-pion scattering phase shifts based on once-- and twice-- subtracted dispersion relations are used as input, whose functional form allows us to show the benefit and accuracy of the method. In particular, we extract from these parametrization the pole positions of the $f_0(500)$ at $\sqrt{s}=(453\pm 15) - i(297 \pm 15)$ MeV, the $\rho(770)$ at $\sq…
Improved $K_{e3}$ radiative corrections sharpen the $K_{\mu 2}$--$K_{l3}$ discrepancy
2021
The measurements of $V_{us}$ in leptonic $(K_{\mu 2})$ and semileptonic $(K_{l3})$ kaon decays exhibit a $3\sigma$ disagreement, which could originate either from physics beyond the Standard Model or some large unidentified Standard Model systematic effects. Clarifying this issue requires a careful examination of all existing Standard Model inputs. Making use of a newly-proposed computational framework and the most recent lattice QCD results, we perform a comprehensive re-analysis of the electroweak radiative corrections to the $K_{e3}$ decay rates that achieves an unprecedented level of precision of $10^{-4}$, which improves the current best results by almost an order of magnitude. No larg…
Spin-dependent potentials from lattice QCD
2006
The spin-dependent corrections to the static inter-quark potential are phenomenologically relevant to describing the fine and hyperfine spin splitting of the heavy quarkonium spectra. We investigate these corrections, which are represented as the field strength correlators on the quark-antiquark source, in SU(3) lattice gauge theory. We use the Polyakov loop correlation function as the quark-antiquark source, and by employing the multi-level algorithm, we obtain remarkably clean signals for these corrections up to intermediate distances of around 0.6 fm. Our observation suggests several new features of the corrections.
Screened potential and the baryon spectrum
2003
We show that in a quark model scheme the use of a screened potential, suggested by lattice QCD, instead of an infinitely rising one with the interquark distance, provides a more adequate description of the high-energy baryon spectrum. In particular an almost perfect parallelism between the predicted and observed number of states comes out throwing new light about the so-called missing resonance problem.
Charm-quark mass from weighted finite energy QCD sum rules
2010
The running charm-quark mass in the scheme is determined from weighted finite energy QCD sum rules involving the vector current correlator. Only the short distance expansion of this correlator is used, together with integration kernels (weights) involving positive powers of s, the squared energy. The optimal kernels are found to be a simple pinched kernel and polynomials of the Legendre type. The former kernel reduces potential duality violations near the real axis in the complex s plane, and the latter allows us to extend the analysis to energy regions beyond the end point of the data. These kernels, together with the high energy expansion of the correlator, weigh the experimental and theo…
Hidden charm molecules in finite volume
2013
In the present paper we address the interaction of pairs of charmed mesons with hidden charm in a finite box. We use the interaction from a recent model based on heavy-quark spin symmetry that predicts molecules of hidden charm in the infinite volume. The energy levels in the box are generated within this model, and from them some synthetic data are generated. These data are then employed to study the inverse problem of getting the energies of the bound states and phase shifts for D (D) over bar or D*(D) over bar*. Different strategies are investigated using the lowest two levels for different values of the box size, and the errors produced are studied. Starting from the upper level, fits t…