相关论文: Chiral order and fluctuations in multi-flavour QCD

We demonstrate that in unquenched quantum electrodynamics (QED), chiral symmetry breaking ceases to exist above a critical number of fermion flavours $N_f$. This is a necessary and sufficient consequence of the fact that there exists a…

We compute the topological susceptibility $\chi_t$ of 2+1-flavor lattice QCD with dynamical M\"obius domain-wall fermions, whose residual mass is kept at 1 MeV or smaller. In our analysis, we focus on the fluctuation of the topological…

We reconsider our former determination of the chiral quark condensate $\langle \bar q q \rangle$ from the related QCD spectral density of the Euclidean Dirac operator, using our Renormalization Group Optimized Perturbation (RGOPT) approach.…

Quantum criticality is a central concept in condensed matter physics, but the direct observation of quantum critical fluctuations has remained elusive. Here we present an x-ray diffraction study of the charge density wave (CDW) in 2H-NbSe2…

This article gives details of our proposal to replace ordinary chiral $SU(3)_L\times SU(3)_R$ perturbation theory $\chi$PT$_3$ by 3-flavor chiral-scale perturbation theory $\chi$PT$_\sigma$. In $\chi$PT$_\sigma$, amplitudes are expanded at…

We show that chiral order in two-dimensional nonreciprocal flocking mixtures is generically unstable. Combining large-scale agent-based simulations with a coarse-grained continuum description, we demonstrate that rotating chiral states…

New relations between the quark spin-flavor contents of the nucleon and axial weak coupling constants are obtained in the chiral quark model with both SU(3) and U(1)-breaking effects. Using the nonsinglet spin combinations, $\Delta_3$ and…

By making use of Numerical Stochastic Perturbation Theory (NSPT) we can compute renormalization constants for Lattice QCD to high orders, e.g. three or four loops for quark bilinears. We report on the status of our computations, which…

The SU(3) breaking effects due to light quark masses on heavy meson masses, decay constants ($F_{D}, F_{D_{s}}$) and the form factor for semileptonic $\overline{B}\rightarrow D^{(\ast)} l\bar{\nu}_{l}$ transitions are formulated in chiral…

Chiral perturbation theory (ChPT) is a low-energy effective field theory of QCD and also a nonlinear sigma model based on the symmetry breaking pattern ${\rm SU}(N_f)\times {\rm SU}(N_f)\to {\rm SU}(N_f)$. In the limit of massless $N_f$…

The consideration of chirality-preserving 2-fermion order parameters may shed new light on the strong CP problem and the breakdown of flavor symmetries. We describe two situations, one having the standard KM picture for weak CP violation…

In the framework of the chiral perturbation theory we computed two- and three-loop corrections to the pion parton distributions which posses $\delta$-function singularities at x->0. This calculation explicitly demonstrates that in the…

In the framework of the instanton vacuum model we make expansion over the current mass $m$ and number of colors $N_c$ and evaluate ${\cal O}(1/N_c, m, m/N_c, m \ln m/N_c)$-corrections to the dynamical quark mass $M$, the quark condensate…

We present positivity bounds, derived from the principles of analyticity, unitarity and crossing symmetry, that constrain the low-energy constants of chiral perturbation theory. Bounds are produced for 2, 3 or more flavours with equal meson…

We investigate the long-range statistical correlations, whereby discuss the nature of the undermining interacting/ noninteracting domains and associated phase transitions under variations of the quark mass and the mass scale that…

Using fast off-lattice Monte Carlo simulations with experimentally accessible fluctuations, we report the first systematic study unambiguously quantifying the shift of the order-disorder transition (ODT) $\chi^*$ of symmetric diblock…

We investigate QCD with a large number of massless flavors with the aid of renormalization group flow equations. We determine the critical number of flavors separating the phases with and without chiral symmetry breaking in SU(Nc) gauge…

We analyze the isospin-breaking corrections to quark condensates within one-loop SU(2) and SU(3) Chiral Perturbation Theory including $m_u\neq m_d$ as well as electromagnetic (EM) contributions. The explicit expressions are given and…

We consider lattice gauge theories at strong coupling with gauge group $U(N_C)$, or $SU(N_C)$ restricted to the meson sector, and coupled to $N_F$ flavors of fundamental representation staggered fermions. We study the formation of a chiral…

Neutral flavour meson oscillations are a fascinating quantum phenomenon that allows for high-precision tests of fundamental symmetries, including CPT invariance. In this contribution, we present the methodology for testing CPT violation in…