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We construct new tests of perturbative QCD by considering a hypothetical tau lepton of arbitrary mass, which decays hadronically through the electromagnetic current. We can explicitly compute its hadronic width ratio directly as an integral…

High Energy Physics - Phenomenology · Physics 2009-09-11 S. J. Brodsky , J. R. Pelaez , N. Toumbas

This short note considers, within the external field approach outlined in hep-ph/0202026, the role of the lowest lying gluon Landau mode in QCD in the high temperature limit. Its influence on a temperature- and field-dependent running…

High Energy Physics - Phenomenology · Physics 2009-11-07 R. A. Schneider

We present analytical results for top-quark decay processes, in an effective field theory beyond the Standard Model, at next-to-leading order in QCD. We parametrize new physics effects using dimension-six operators, and consider all…

High Energy Physics - Phenomenology · Physics 2014-07-16 Cen Zhang

We exploit theoretical results on the meson spectrum within the framework of a Bethe-Salpeter (BS) formalism adjusted for QCD, in order to extract an ``experimental'' coupling \alpha_s^{exp}(Q^2) below 1 GeV by comparison with the data. Our…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. Baldicchi , A. V. Nesterenko , G. M. Prosperi , D. V. Shirkov , C. Simolo

We perform a well defined derivative expansion to obtain the time dependent effective theory for a BCS superconductor at finite temperature, using an arbitrary curve in the complex time plane. Our expansion is unique, being free of any…

Superconductivity · Physics 2007-05-23 T. S. Evans , D. A. Steer

We formulate Noncommutative Qauntum Field Theory in terms of fields defined as mean value over coherent states of the noncommutative plane. No *-product is needed in this formulation and noncommutativity is carried by a modified Fourier…

High Energy Physics - Theory · Physics 2009-11-10 Anais Smailagic , Euro Spallucci

We use the Aleph data on vector and axial-vector spectral functions to test simple duality properties of QCD in the large Nc limit, which emerge in the approximation of a minimal hadronic ansatz of a spectrum of narrow states. These duality…

High Energy Physics - Phenomenology · Physics 2008-11-26 S. Peris , B. Phily , E. de Rafael

The structure of the QFT expansion is studied in the framework of a new "Invariant analytic" version of the perturbative QCD. Here, an invariant (running) coupling $a(Q^2/\Lambda^2)=\beta_1\alpha_s(Q^2)/4\pi$ is transformed into a…

High Energy Physics - Theory · Physics 2014-11-18 D. V. Shirkov

We argue that the appearance of the Landau pole in the running coupling of QCD introduces 1/Q^2 power corrections in current correlation functions. These terms are not accounted for by the standard operator product expansion and is the…

High Energy Physics - Phenomenology · Physics 2009-10-30 R. Akhoury , V. I. Zakharov

We study deviations from the perturbative asymptotic behaviour in the running QCD coupling by analysing non-perturbative measurements of alpha_s (p) at low momenta as obtained from the lattice three-gluon vertex. Our exploratory study…

High Energy Physics - Phenomenology · Physics 2009-10-31 G. Burgio , F. Di Renzo , C. Parrinello , C. Pittori

We study the molecular mode coupling theory for a liquid of diatomic molecules. The equations for the critical tensorial nonergodicity parameters ${\bf F}_{ll'}^m(q)$ and the critical amplitudes of the $\beta$ - relaxation ${\bf…

Disordered Systems and Neural Networks · Physics 2016-08-31 A. Winkler , A. Latz , R. Schilling , C. Theis

We explicitly compute the one-loop exact beta function for a nonlocal extension of the standard gauge theory, in particular Yang-Mills and QED. The theory, made of a weakly nonlocal kinetic term and a local potential of the gauge field, is…

High Energy Physics - Theory · Physics 2016-08-03 Leonardo Modesto , Marco Piva , Leslaw Rachwal

We study a number of different ingredients related to the $\theta$ dependence, metastable excited vacuum states and other related subjects using a simplified version of QCD, the so-called "deformed QCD". This model is a weakly coupled gauge…

High Energy Physics - Phenomenology · Physics 2015-06-22 Amit Bhoonah , Evan Thomas , Ariel R. Zhitnitsky

The theory relevant to the study of matter in equilibrium with the radiation field is thermal quantum electrodynamics (TQED). We present a formulation of the theory, suitable for non relativistic fluids, based on a joint functional integral…

Quantum Physics · Physics 2009-11-13 Pascal R. Buenzli , Philippe A. Martin , Marc D. Ryser

We consider a hydrogen-like atom in a quantized electromagnetic field which is modeled by means of a no-pair operator acting in the positive spectral subspace of the free Dirac operator minimally coupled to the quantized vector potential.…

Mathematical Physics · Physics 2011-12-02 Martin Könenberg , Oliver Matte , Edgardo Stockmeyer

We use the linear sigma model with quarks to study the QCD phase diagram from the point of view of chiral symmetry restoration. We compute the leading order effective potential for high and low temperatures and finite quark chemical…

High Energy Physics - Phenomenology · Physics 2018-01-31 Alejandro Ayala , Saul Hernandez-Ortiz , Luis A. Hernandez

The exact expression for the phase-dependent linear conductance of a weakly damped superconducting quantum point contact is obtained. The calculation is performed by summing up the complete perturbative series in the coupling between the…

Condensed Matter · Physics 2016-08-15 A. Levy Yeyati , A. Martín-Rodero , J. C. Cuevas

The ALEPH data on hadronic tau-decay is throughly analysed in the framework of QCD. The perturbative calculations are performed in 1-4-loop approximation. The analytical properties of the polarization operators are used in the whole complex…

High Energy Physics - Phenomenology · Physics 2009-11-07 B. V. Geshkenbein

Based on the recently developed light-front similarity renormalization group approach and the light-front heavy quark effective theory, we derive analytically from first-principles QCD a heavy quark light-front Hamiltonian which contains…

High Energy Physics - Phenomenology · Physics 2011-01-25 Wei-Min Zhang

We report on recent experimental and theoretical developments in our understanding of the QCD running coupling \alpha_s in QCD's nonperturbative regime. They allow us to analytically compute the hadron mass spectrum, with \Lambda_s the only…

High Energy Physics - Phenomenology · Physics 2018-11-15 Alexandre Deur