Publications (99)
NN scattering in higher derivative formulation of baryon chiral perturbation theory
D. Djukanovic, J. Gegelia, S. Scherer +1
We consider a new approach to the nucleon-nucleon scattering problem in the framework of the higher-derivative formulation of baryon chiral perturbation theory. Starting with a Lor…
Generalized polarizabilities and the spin-averaged amplitude in virtual Compton scattering off the nucleon
D. Drechsel, G. Knoechlein, A. Metz +1
We discuss the low-energy behavior of the spin-averaged amplitude of virtual Compton scattering (VCS) off a nucleon. Based on gauge invariance, Lorentz invariance and the discrete…
Accurate Test of Chiral Dynamics in the \boldmath Reaction
D. Hornidge, P. Aguar Bartolome, J. R. M. Annand +64
A precision measurement of the differential cross sections and the linearly polarized photon asymmetry $Σ\equiv (dÏ_\perp - dÏ_\parallel) \slash (dÏ_\perp + dÏ_\para…
Consistency of the interaction in chiral perturbation theory
N. Wies, J. Gegelia, S. Scherer
We analyze the constraint structure of a spin-3/2 particle interacting with a pseudoscalar. Requiring the self consistency of the considered effective field theory imposes restrict…
Compton Scattering by a Pion and off--Shell Effects
S. Scherer, H. W. Fearing
We consider Compton scattering by a pion in the framework of chiral perturbation theory. We investigate off--shell effects in the s-- and u--channel pole diagrams. For that purpose…
Pion Generalized Dipole Polarizabilities by Virtual Compton Scattering
C. Unkmeir, A. Ocherashvili, T. Fuchs +2
We present a calculation of the cross section and the event generator of the reaction . This reaction is sensitive to the pion generalized dipole polarizabilities, n…
Generalized polarizabilities and the chiral structure of the nucleon
T. R. Hemmert, B. R. Holstein, G. Knoechlein +1
We discuss the virtual Compton scattering reaction at low energies. We present results for the generalized polarizabilities of the nucleon obtained in heavy baryon…
Magnetic dipole moment of the in chiral perturbation theory
C. Hacker, N. Wies, J. Gegelia +1
The magnetic dipole moment of the is calculated in the framework of manifestly Lorentz-invariant baryon chiral perturbation theory in combination with the extended on-ma…
Light Meson Dynamics Workshop. Mini proceedings
J. Bijnens, R. Escribano, S. Fang +16
The mini-proceedings of the Light Meson Dynamics Workshop held in Mainz from February 10th to 12th, 2014, are presented. The web page of the conference, which contains all talks, c…
Effective Field Theory of the Single-Nucleon Sector
S. Scherer
We address the issue of a consistent power counting scheme in manifestly Lorentz-invariant baryon chiral perturbation theory. We discuss the inclusion of vector mesons in the calcu…
Mass and width of the resonance using complex-mass renormalization
T. Bauer, Y. Unal, A. Kucukarslan +1
We discuss the pole mass and the width of the resonance to third order in chiral effective field theory. In our calculation we choose the complex-mass renormalization sc…
Virtual Compton Scattering--Generalized Polarizabilities of Nucleons and Pions
S. Scherer
Virtual Compton scattering off nucleons and pions at low energies is discussed. Predictions for the generalized polarizabilities of the nucleon are presented within the framework o…
Probing the convergence of perturbative series in baryon chiral perturbation theory
D. Djukanovic, J. Gegelia, S. Scherer
Using the examples of pion-nucleon scattering and the nucleon mass we analyze the convergence of perturbative series in the framework of baryon chiral perturbation theory. For both…
Nucleon-to-Delta transition form factors in chiral effective field theory using the complex-mass scheme
M. Hilt, T. Bauer, S. Scherer +1
We calculate the form factors of the electromagnetic nucleon-to--resonance transition to third chiral order in manifestly Lorentz-invariant chiral effective field theory. For t…
Nucleon Form Factors of the Isovector Axial-Vector Current: Situation of Experiments and Theory
M. R. Schindler, S. Scherer
The theoretical and experimental status of the isovector axial-vector current form factors G_A(q^2) and G_P(q^2) of the nucleon is reviewed. We also describe a new calculation of t…
Hadron structure and the limitations of phenomenological models in electromagnetic reactions
J. H. Koch, V. Pascalutsa, S. Scherer
The description of electromagnetic reactions at intermediate energies, such as pion electroproduction or (virtual) Compton scattering, traditionally starts from covariant tree-leve…
Polarization Phenomena in Small-Angle Photoproduction of e+e- Pairs and the Gerasimov-Drell-Hearn Sum Rule
A. I. L'vov, S. Scopetta, D. Drechsel +1
Photoproduction of pairs at small angles is investigated as a tool to determine the functions and entering the real-photon forward Compton scattering amplitude…
Constraint analysis for the interaction of the vector-meson octet with the baryon octet
Y. Unal, A. Kucukarslan, S. Scherer
We describe a constraint analysis for the interaction of the vector-meson octet with the baryon octet. Applying Dirac's Hamiltonian method, we verify that the standard interaction…
Pion photo- and electroproduction with chiral MAID
M. Hilt, B. C. Lehnhart, S. Scherer +1
We present a calculation of pion photo- and electroproduction in manifestly Lorentz-invariant baryon chiral perturbation theory up to and including order . We fix the low-ener…
Magnetic moment of the Roper resonance
T. Bauer, J. Gegelia, S. Scherer
The magnetic moment of the Roper resonance is calculated in the framework of a low-energy effective field theory of the strong interactions. A systematic power-counting procedure i…
Physics opportunities at RHIC and LHC
S. Scherer, S. A. Bass, M. Belkacem +18
Nonequilibrium models (three-fluid hydrodynamics, UrQMD, and quark molecular dynamics) are used to discuss the uniqueness of often proposed experimental signatures for quark matter…
Electromagnetic transition form factors of the Roper resonance in effective field theory
T. Bauer, S. Scherer, L. Tiator
We analyze the form factors of the electromagnetic nucleon-to-Roper-resonance transition in the framework of low-energy effective field theory. A systematic power-counting procedur…
Pion Photo- and Electroproduction and the Chiral MAID Interface
M. Hilt, B. C. Lehnhart, S. Scherer +1
We discuss the extended on-mass-shell scheme for manifestly Lorentz-invariant baryon chiral perturbation theory. We present a calculation of pion photo- and electroproduction up to…
Two-nucleon problem in semi-relativistic baryon chiral perturbation theory
D. Djukanovic, J. Gegelia, S. Scherer +1
We consider a symmetry-preserving approach to the nucleon-nucleon scattering problem in the framework of the higher-derivative formulation of baryon chiral perturbation theory. Wit…
Pion electroproduction, PCAC, chiral Ward identities, and the axial form factor revisited
T. Fuchs, S. Scherer
We re-investigate Adler's PCAC relation in the presence of an external electromagnetic field within the framework of QCD coupled to external fields. We discuss pion electroproducti…
The polarizability of the pion: no conflict between dispersion theory and chiral perturbation theory
B. Pasquini, D. Drechsel, S. Scherer
Recent attempts to determine the pion polarizability by dispersion relations yield values that disagree with the predictions of chiral perturbation theory. These dispersion relatio…
Extension of the Chiral Perturbation Theory Meson Lagrangian to Order
H. W. Fearing, S. Scherer
We have derived the most general chirally invariant Lagrangian for the meson sector at order . The result provides an extension of the standard Gasser-Leutwyler L…
Complex mass renormalization in EFT
D. Djukanovic, J. Gegelia, A. Keller +1
We consider an effective field theory of unstable particles (resonances) using the complex-mass renormalization. As an application we calculate the masses and the widths of the $Ï…
Contribution of the meson to the axial nucleon-to- transition form factors
Y. Unal, A. Kucukarslan, S. Scherer
We analyze the low- behavior of the axial form factor , the induced pseudoscalar form factor , and the axial nucleon-to- transition form factors $C^A_5…
Introduction to Chiral Perturbation Theory
S. Scherer
This article provides a pedagogical introduction to the basic concepts of chiral perturbation theory and is designed as a text for a two-semester course on that topic. Chapter 1 se…
The Effect of Dynamical Parton Recombination on Event-by-Event Observables
S. Haussler, S. Scherer, M. Bleicher
Within a dynamical quark recombination model we explore various proposed event-by-event observables sensitive to the microscopic structure of the QCD-matter created at RHIC energie…
Renormalization of relativistic baryon chiral perturbation theory and power counting
T. Fuchs, J. Gegelia, G. Japaridze +1
We discuss a renormalization scheme for relativistic baryon chiral perturbation theory which provides a simple and consistent power counting for renormalized diagrams. The method i…
Infrared regularization of baryon chiral perturbation theory reformulated
M. R. Schindler, J. Gegelia, S. Scherer
We formulate the infrared regularization of Becher and Leutwyler in a form analogous to our recently proposed extended on-mass-shell renormalization. In our formulation, IR regular…
Power counting in baryon chiral perturbation theory including vector mesons
T. Fuchs, M. R. Schindler, J. Gegelia +1
It is demonstrated that using a suitable renormalization condition one obtains a consistent power counting in manifestly Lorentz-invariant baryon chiral perturbation theory includi…
The Anomalous Decay eta -> pi pi gamma gamma
G. Knoechlein, S. Scherer, D. Drechsel
We investigate the rare radiative eta decay modes eta -> pi+ pi- gamma gamma and eta -> pi0 pi0 gamma gamma within the framework of chiral lagrangians at o(p^4) and present photon…
Path integral quantization for massive vector bosons
D. Djukanovic, J. Gegelia, S. Scherer
A parity-conserving and Lorentz-invariant effective field theory of self-interacting massive vector fields is considered. For the interaction terms with dimensionless coupling cons…
Vector form factor of the pion in chiral effective field theory
D. Djukanovic, J. Gegelia, A. Keller +2
The vector form factor of the pion is calculated in the framework of chiral effective field theory with vector mesons included as dynamical degrees of freedom. To construct an effe…
Nonequilibrium dynamics of a hadronizing quark-gluon plasma
M. Hofmann, J. M. Eisenberg, S. Scherer +4
We investigate the hadronic cooling of a quark droplet within a microscopic model. The color flux tube approach is used to describe the hadronization of the quark phase. The model…
Pion polarizabilities: No conflict between dispersion theory and ChPT
B. Pasquini, D. Drechsel, S. Scherer
Recent attempts to determine the pion polarizability by dispersion relations yield values that disagree with the predictions of chiral perturbation theory. These dispersion relatio…
Real and Virtual Compton Scattering at Low Energies
S. Scherer
These lectures give a pedagogical introduction to real and virtual Compton scattering at low energies. We will first discuss real Compton scattering off a point particle as well as…
Virtual Compton Scattering and Generalized Polarizabilities of the Nucleon in Heavy Baryon Chiral Perturbation Theory
T. R. Hemmert, B. R. Holstein, ; G. Knoechlein +1
The spin-independent part of the virtual Compton scattering (VCS) amplitude from the nucleon is calculated within the framework of heavy baryon chiral perturbation theory (HBChPT).…
On the definition of the Îmass and width
D. Djukanovic, J. Gegelia, S. Scherer
In the framework of effective field theory we show that, at two-loop order, the mass and width of the Îresonance defined via the (relativistic) Breit-Wigner parametrization both d…
Structure analysis of the virtual Compton scattering amplitude at low energies
D. Drechsel, G. Knoechlein, A. Yu. Korchin +2
We analyze virtual Compton scattering off the nucleon at low energies in a covariant, model-independent formalism. We define a set of invariant functions which, once the irregular…
Mass and width of the Roper resonance using complex-mass renormalization
D. Djukanovic, J. Gegelia, S. Scherer
The pole mass and the width of the Roper resonance are calculated as functions of the pion mass in the framework of low-energy effective field theory of the strong interactions. We…
Pion photo- and electroproduction and the chiral MAID interface
M. Hilt, B. C. Lehnhart, S. Scherer +1
We discuss the extended on-mass-shell scheme for manifestly Lorentz-invariant baryon chiral perturbation theory. We present a calculation of pion photo- and electroproduction up to…
The off-shell electromagnetic form factors of pions and kaons in chiral perturbation theory
T. E. Rudy, H. W. Fearing, S. Scherer
The off-shell electromagnetic vertex of a (pseudo-) scalar particle contains, in general, two form factors F and G which depend, in addition to the squared momentum transfer, on th…
and at in the NJL model
A. A. Bel'kov, A. V. Lanyov, S. Scherer
We discuss the processes and at in the momentum expansion. The calculation involves tree--level, one--loop and two--loop diagrams of a c…
Reply to "Comment on `The polarizability of the pion: no conflict between dispersion theory and chiral perturbation theory'"
B. Pasquini, D. Drechsel, S. Scherer
We reply to the Comment by Fil'kov and Kashevarov, arXiv:0805.4486 [hep-ph]. We show that the discrepancies between ChPT and dispersion theory, reported for the polarizability of t…
Effective Hamiltonians with Relativistic Corrections II: Application to Compton Scattering by a Proton
S. Scherer, G. I. Poulis, H. W. Fearing
We discuss two different methods of obtaining ``effective Hamiltonians'' of the electromagnetic interaction which include relativistic corrections. One is the standard…
Microscopic coloured quark-dynamics in the soft non-perturbative regime -- Description of hadron formation in relativistic S+Au collisions at CERN
S. Scherer, M. Hofmann, M. Bleicher +3
The quark-molecular-dynamics model is used to study microscopically the dynamics of the coloured quark phase and the subsequent hadron formation in relativistic S+Au collisions at…
Generalized dipole polarizabilities and the spatial structure of hadrons
A. I. L'vov, S. Scherer, B. Pasquini +2
We present a phenomenological discussion of spin-independent, generalized dipole polarizabilities of hadrons entering the virtual Compton scattering process gamma* h -> gamma h. We…
Virtual Compton Scattering off the Pseudoscalar Meson Octet
T. Fuchs, B. Pasquini, C. Unkmeir +1
We present a calculation of the virtual Compton scattering amplitude for the pseudoscalar meson octet in the framework of chiral perturbation theory at . We calculat…
Measurement of the pi^+ meson polarizabilities via the gamma p->gamma pi^+ n reaction
J. Ahrens, V. M. Alexeev, J. R. M. Annand +28
An experiment on the radiative pi^+ meson photoproduction from the proton (gamma p->gamma pi^+ n) was carried out at the Mainz Microtron MAMI in the kinematic region 537 MeV <E_{ga…
Complex-mass scheme and perturbative unitarity
T. Bauer, J. Gegelia, G. Japaridze +1
We derive cutting rules for loop integrals containing propagators with complex masses. Using a field-theoretical model of a heavy vector boson interacting with a light fermion, we…
Complex-mass renormalization in chiral effective field theory
D. Djukanovic, J. Gegelia, A. Keller +1
We consider a low-energy effective field theory of vector mesons and Goldstone bosons using the complex-mass renormalization. As an application we calculate the mass and the width…
Axial-vector nucleon-to-delta transition form factors using the complex-mass renormalization scheme
Y. Ãnal, A. Küçükarslan, S. Scherer
We investigate the axial-vector nucleon-to-delta transition form factors in the framework of relativistic baryon chiral perturbation theory at the one-loop order using the complex-…
Infrared renormalization of two-loop integrals and the chiral expansion of the nucleon mass
M. R. Schindler, D. Djukanovic, J. Gegelia +1
We describe details of the renormalization of two-loop integrals relevant to the calculation of the nucleon mass in the framework of manifestly Lorentz-invariant chiral perturbatio…
Consistency of the effective-field-theory approach to the nucleon-nucleon interaction problem revisited
J. Gegelia, S. Scherer
It is argued that Weinberg's approach to the nucleon-nucleon (NN) interaction problem within effective field theory provides a consistent power counting for renormalized diagrams.…
Generalized polarizabilities of the pion in chiral perturbation theory
C. Unkmeir, S. Scherer, A. I. L'vov +1
We present a calculation of the virtual Compton scattering amplitude for $γ^\ast+Ï\to γ+Ï$ in the framework of chiral perturbation theory at . We explicitly deri…
Improving the ultraviolet behavior in baryon chiral perturbation theory
D. Djukanovic, M. R. Schindler, J. Gegelia +1
We introduce a new formulation of baryon chiral perturbation theory which improves the ultraviolet behavior of propagators and can be interpreted as a smooth cutoff regularization…
Generalized Polarizabilities in a Constituent Quark Model
B. Pasquini, S. Scherer, D. Drechsel
We discuss low-energy virtual Compton scattering off the proton within the framework of a nonrelativistic constituent quark model. A simple interpretation of the spin-averaged gene…
The rare decay in chiral perturbation theory
G. Kn"ochlein, S. Scherer, D. Drechsel
We investigate the rare radiative eta decay modes and within the framework of chiral perturbation theory at . We present photon spec…
Low-energy and low-momentum representation of the virtual Compton scattering amplitude
D. Drechsel, G. Knoechlein, A. Yu. Korchin +2
We perform an expansion of the virtual Compton scattering amplitude for low energies and low momenta and show that this expansion covers the transition from the regime to be invest…
Statistical Mechanics of semi-classical colored Objects
M. Hofmann, M. Bleicher, S. Scherer +3
A microscopic model of deconfined matter based on color interactions between semi-classical quarks is studied. A hadronization mechanism is imposed to examine the properties and th…
Virtual Compton scattering off spin-zero particles at low energies
H. W. Fearing, S. Scherer
We discuss the low-energy behavior of the virtual Compton scattering amplitude off a spin-zero target. We first compare various methods of obtaining a low-energy expression based e…
Chiral dynamics of rare eta decays and virtual Compton scattering off the nucleon
S. Scherer
Two different topics relevant for DANE and CEBAF, respectively, are covered. First we analyze the rare radiative eta decay mode within the framework of chiral p…
Polarization Phenomena in Small-Angle Photoproduction of e+e- Pairs and the GDH Sum Rule
A. I. L'vov, S. Scopetta, D. Drechsel +1
We discuss a possibility to measure the spin-dependent part of the forward Compton scattering amplitude through interference effects of the Bethe-Heitler and virtual Compton scatte…
How to define physical properties of unstable particles
J. Gegelia, S. Scherer
In the framework of effective quantum field theory we address the definition of physical quantities characterizing unstable particles. With the aid of a one-loop calculation, we st…
Including the resonance in baryon chiral perturbation theory
C. Hacker, N. Wies, J. Gegelia +1
Baryon chiral perturbation theory with explicit degrees of freedom is considered. Using the extended on-mass-shell renormalization scheme, a manifestly Lorentz-invariant…
The anomalous chiral perturbation theory meson Lagrangian to order revisited
T. Ebertshäuser, H. W. Fearing, S. Scherer
We present a revised and extended construction of the mesonic Lagrangian density in chiral perturbation theory (ChPT) at order in the anomalous (or epsilon) sector, ${\cal{L}…
Axial, induced pseudoscalar, and pion-nucleon form factors in manifestly Lorentz-invariant chiral perturbation theory
M. R. Schindler, T. Fuchs, J. Gegelia +1
We calculate the nucleon form factors G_A and G_P of the isovector axial-vector current and the pion-nucleon form factor G_piN in manifestly Lorentz-invariant baryon chiral perturb…
- Mixing in Large- Chiral Perturbation Theory
P. Bickert, P. Masjuan, S. Scherer
We present a calculation of the - mixing in the framework of large- chiral perturbation theory. A general expression for the - mixing at next-to-next-to-lead…
Chiral expansion of the nucleon mass to order q^6
M. R. Schindler, D. Djukanovic, J. Gegelia +1
We present the results of a complete two-loop calculation at order q^6 of the nucleon mass in manifestly Lorentz-invariant chiral perturbation theory. The renormalization is perfor…
Quantum electrodynamics for vector mesons
D. Djukanovic, M. R. Schindler, J. Gegelia +1
Quantum electrodynamics for mesons is considered. It is shown that, at tree level, the value of the gyromagnetic ratio of the is fixed to 2 in a self-consistent effecti…
Electromagnetic form factors of the nucleon in effective field theory
T. Bauer, J. C. Bernauer, S. Scherer
We calculate the electromagnetic form factors of the nucleon to third chiral order in manifestly Lorentz-invariant effective field theory. The rho and omega mesons as well as the D…
Generalized dipole polarizabilities of the pion
S. Scherer
We discuss the virtual Compton scattering amplitude $γ^\ast+Ï\to γ+Ï$ which enters the reaction . The low-energy scattering amplitude is divided into a…
Interaction of the vector-meson octet with the baryon octet in effective field theory
Y. Unal, A. Kucukarslan, S. Scherer
We analyze the constraint structure of the interaction of vector mesons with baryons using the classical Dirac constraint analysis. We show that the standard interaction in terms o…
Universality of the rho-meson coupling in effective field theory
D. Djukanovic, M. R. Schindler, J. Gegelia +2
It is shown that both the universal coupling of the rho-meson and the Kawarabayashi-Suzuki-Riadzuddin-Fayyazuddin expression for the magnitude of its coupling constant follow from…
A new determination of the anomalous amplitude via data
I. Giller, A. Ocherashvili, T. Ebertshauser +2
We discuss the reaction with the purpose of obtaining information on the anomalous amplitude . We compare a full calcu…
Baryon masses and nucleon sigma terms in manifestly Lorentz-invariant baryon chiral perturbation theory
B. C. Lehnhart, J. Gegelia, S. Scherer
We discuss the masses of the ground state baryon octet and the nucleon sigma terms in the framework of manifestly Lorentz-invariant baryon chiral perturbation theory. In order to o…
Generalized polarizabilities of the proton in a constituent quark model revisited
B. Pasquini, S. Scherer, D. Drechsel
We study low-energy virtual Compton scattering off the proton within the framework of a nonrelativistic constituent quark model. The Compton tensor is divided into two separately g…
The physical meaning of scattering matrix singularities in coupled-channel formalisms
S. Capstick, A. Svarc, L. Tiator +8
The physical meaning of bare and dressed scattering matrix singularities has been investigated. Special attention has been attributed to the role of well known invariance of scatte…
Effective Hamiltonians with Relativistic Corrections I: The Foldy--Wouthuysen transformation versus the direct Pauli reduction
H. W. Fearing, G. I. Poulis, S. Scherer
Two different methods of obtaining ``effective Hamiltonians'' which include relativistic corrections to nonrelativistic calculations are discussed, the standard Foldy--…
An Effective Chiral Meson Lagrangian at from the NJL Model
A. A. Bel'kov, A. V. Lanyov, A. Schaale +1
In this work we present a strong chiral meson Lagrangian up to and including in the momentum expansion. It is derived from the Nambu--Jona-Lasinio (NJL) model using the he…
Infrared and extended on-mass-shell renormalization of two-loop diagrams
M. R. Schindler, J. Gegelia, S. Scherer
Using a toy model Lagrangian we demonstrate the application of both infrared and extended on-mass-shell renormalization schemes to multiloop diagrams by considering as an example a…
Quark-mass and corrections to the vector-meson pseudoscalar-meson photon () interaction
H. C. Lange, A. Krasniqi, S. Scherer
We analyze quark-mass and corrections to all of the radiative transitions between the vector-meson nonet and the pseudoscalar-meson nonet within a chiral effective Lagrangi…
Field transformations and simple models illustrating the impossibility of measuring off-shell effects
H. W. Fearing, S. Scherer
In the context of simple models illustrating field transformations in Lagrangian field theories we discuss the impossibility of measuring off-shell effects in nucleon-nucleon brems…
Power counting in relativistic baryon chiral perturbation theory
T. Fuchs, J. Gegelia, G. Japaridze +1
We consider a renormalization scheme for relativistic baryon chiral perturbation theory which provides a simple and consistent power counting for renormalized diagrams. As an appli…
Hadron structure in manifestly Lorentz-invariant baryon chiral perturbation theory
T. Fuchs, M. R. Schindler, J. Gegelia +1
We briefly outline the so-called extended on-mass-shell renormalization scheme for manifestly Lorentz-invariant baryon chiral perturbation theory which provides a simple and consis…
Ostrogradsky's Hamilton formalism and quantum corrections
J. Gegelia, S. Scherer
By means of a simple scalar field theory it is demonstrated that the Lagrange formalism and Ostrogradsky's Hamilton formalism in the presence of higher derivatives, in general, do…
Hadron Polarizabilities and Form Factors
D. Drechsel, J. Becker, A. Z. Dubnickova +17
This is the summary of the working group on Hadron Polarizabilities and Form Factors of the Chiral Dynamics Workshop in Mainz, September 1-5, 1997.
Chiral Meson Lagrangians from the QCD Based NJL Model Modified by Nonlocal Effects
A. A. Bel'kov, A. V. Lanyov, A. Schaale +1
Starting from a QCD inspired bilocal quark interaction we obtain a local effective meson lagrangian. In contrast to previous local (NJL-like) approaches, we include nonlocal correc…
Signatures in the Planck Regime
S. Hossenfelder, M. Bleicher, S. Hofmann +3
String theory suggests the existence of a minimum length scale. An exciting quantum mechanical implication of this feature is a modification of the uncertainty principle. In contra…
A simple model illustrating the impossibility of measuring off-shell effects
S. Scherer, H. W. Fearing
We consider a simple model and make use of field transformations in Lagrangian field theories to illustrate the impossibility of measuring off-shell effects in nucleon-nucleon brem…
Compton scattering from a pion and off-shell effects
S. Scherer
We discuss the most general form of the electromagnetic vertex of an off-shell pion. The framework of chiral perturbation theory is used to illustrate the representation dependence…
Complex-mass scheme and resonances in EFT
T. Bauer, D. Djukanovic, J. Gegelia +2
The complex-mass scheme (CMS) provides a consistent framework for dealing with unstable particles in quantum field theory and has been successfully applied to various loop calculat…
Current Status of Quark Gluon Plasma Signals
D. Zschiesche, S. Bass, M. Bleicher +9
Compelling evidence for the creation of a new form of matter has been claimed to be found in Pb+Pb collisions at SPS. We discuss the uniqueness of often proposed experimental signa…
Virtual Compton scattering off the nucleon at low energies
S. Scherer, A. Yu. Korchin, J. H. Koch
We investigate the low-energy behavior of the four-point Green's function describing virtual Compton scattering off the nucleon. Using Lorentz invariance, gauge invaria…
Field Transformations and the Classical Equation of Motion in Chiral Perturbation Theory
S. Scherer, H. W. Fearing
The construction of effective Lagrangians commonly involves the application of the `classical equation of motion' to eliminate redundant structures and thus generate the minimal nu…