Related papers: Radiation Zeros as an Observable to test Physics b…
The vanishing of the cross section for particular points in phase space - radiation zeros - is examined for the process $ q \bar q \to W^+W^- \gamma$ at high energy. Unlike the process $q \bar q' \to W^\pm \gamma$, actual zeros only occur…
The process $e^+e^- \to q \bar q \gamma$ contains radiation zeros, i.e. configurations of the four-momenta for which the scattering amplitude vanishes. We calculate the positions of these zeros for $u$--quark and $d$--quark production and…
Standard radiation zeros arise from the factorization properties of tree-level amplitudes involving a massless photon and can occur when all charged particles in the initial and final state have the same sign. We investigate how several…
The process $eq \to eq +\gamma$ exhibits radiation zeros, i.e. configurations of the final-state particles for which the scattering amplitude vanishes. We study these zeros for both $e^+u$ and $e^+d$ scattering. The latter exhibits a type…
The production of single photons plus missing energy at future $e^{+}e^{-}$ colliders can provide a testing ground for non-standard $WW\gamma$ couplings. We show that even with conservative estimates of systematic errors there is still…
The process $e^+e^- \to \tau \bar\tau \gamma$ contains configurations of the four-momenta for which the scattering amplitude vanishes (Radiation Zeros or Null Zone). These Radiation Zeros only occur for couplings given by a gauge theory, in…
In experimental nuclear astrophysics it is common knowledge that reaction cross sections must be measured in the astrophysically relevant, low energy ranges or at least as close to them as possible. In most of the cases, however, it is…
We discuss a numerical analysis employing the density of partition function zeroes which permits effective distinction between phase transitions of first and second order, elucidates crossover between such phase transitions and gives a new…
The Standard Model amplitudes for processes where one or more gauge bosons are emitted exhibit zeros in the angular distributions. The theoretical and experimental aspects of these radiation amplitude zeros are reviewed and some recent…
A cubic kilometer scale experiment has been proposed to detect cosmic neutrinos of energy from tens of GeV up to the highest energies observed for cosmic rays, around 10**20 eV, or possibly even beyond. Detection efficiencies depend…
We discuss the question if the upcoming generation of collider and low-energy experiments can successfully probe the nature of the electroweak phase transition. In particular, we are interested in phase transitions strong enough for…
We show from general principles that there must be a center of mass energy, $\sqrt s_0$, where the polarization asymmetry $A=\Delta \sigma({\gamma e \to W \nu })/ \sigma({\gamma e \to W \nu })$ for circularly-polarized photon and electron…
In the Coulomb field of nucleus cut off on it size, besides usual atomic states, there are additional ones. These anomalous states are deep (in the range of $10\,MeV$) in the Dirac sea and can exist solely during a macroscopic acceleration…
A recently developed technique for the determination of the density of partition function zeroes using data coming from finite-size systems is extended to deal with cases where the zeroes are not restricted to a curve in the complex plane…
We suggest returning to a different presentation of the e+e- \to \bar{f} f data off the Z peak, with the hope of using zeroes of specific amplitudes to enhance the sensitivity to new physics.
Quantum phase transitions (QPTs) in the spin-boson model with/without the rotating-wave approximation (RWA) are systematically investigated through variational calculations using a sub-Ohmic bath with high spectral density. Four cases…
This paper explores the use of a cumulant method to determine the zeros of partition functions for continuous phase transitions. Unlike a first-order transition, with a uniform density of zeros near the transition point, a continuous…
Some form factors of ground-state hadrons with spin might show a zero crossing at spacelike momenta of electron-hadron scattering. In the timelike region of hadron-antihadron production by electron-positron collisions the form factors…
We perform a detailed analysis of the processes $e^+e^- \rightarrow \bar{\nu} \nu\gamma$ and $\bar{\nu}\nu\bar{q}q$ at future linear $e^+e^-$ colliders and assess their sensitivity to anomalous gauge boson couplings. We consider center of…
We study the Roberge-Weiss phase transition numerically. The phase transition is associated with the discontinuities in the quark-number density at specific values of imaginary quark chemical potential. We parameterize the quark number…