Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · hep-ph/0404078

The radiative return at phi- and B-factories: FSR for muon pair production at next-to-leading order

Henryk Czyz·Agnieszka Grzelinska·Johann H. Kuhn·German Rodrigo
View original source ↗Read source document ↗Export metadata ↓

Abstract

Muon pair production through the radiative return is of importance for a measurement of the hadronic production cross section in two ways: it provides an independent calibration and it may give rise to an important background for a measurement of the pion form factor. With this motivation the Monte Carlo event generator PHOKHARA is extended to include next-to-leading order radiative corrections to the reaction $e^+e^-\to μ^+μ^-γ$. Furthermore, virtual ISR corrections to FSR from pions are introduced, which extends the applicability of the generator into a new kinematical regime. Finally, the effect of photon vacuum polarization is introduced into this new version of the generator.

Explore related subjects

hep-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Henryk Czyz, Agnieszka Grzelinska, Johann H. Kuhn, German Rodrigo. 2005-01-27. The radiative return at phi- and B-factories: FSR for muon pair production at next-to-leading order. https://doi.org/10.1140/epjc%2Fs2004-02103-1

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

The Physics of Herwig 7

We present the physics foundations and recent developments of Herwig 7, the modern successor of the original HERWIG and Herwig++ series. Herwig 7 provides a flexible and systematically improvable framework for the simulation of high-energy lepton and hadron collisions, with particular emphasis on QCD and EW effects. Hard scattering processes are generated within the automated Matchbox framework, which integrates external amplitude providers, supports tree-level, next-to-leading-order (NLO) and loop-induced matrix elements, and implements subtraction schemes, multi-channel phase-space sampling, dynamic scale choices and both POWHEG- and MC@NLO-type matching algorithms. Consistent multijet merging at LO and NLO is provided, enabling precise predictions across a wide range of SM processes. Parton radiation is simulated using two complementary showers: an angular-ordered shower incorporating QCD coherence and the heavy-quark dead-cone effect, and a dipole shower optimised for NLO matching and multijet merging. Higher-order corrections are included through matrix-element corrections and dedicated reweighting techniques, while QED and EW radiation are treated using a YFS formalism and EW showering algorithms. The modelling of non-perturbative physics employs an advanced cluster hadronization framework with improved cluster formation, fission and decay, as well as colour reconnection models, heavy-quark effects and interfaces to alternative hadronization schemes. An extended eikonal multiple-partonic-scattering model, incorporating semi-hard and soft components together with diffractive interactions, enables realistic descriptions of minimum-bias and underlying-event data. Herwig 7 thus represents a versatile event generator, providing a coherent, modular and extensible platform for Standard Model and beyond-the-Standard-Model collider phenomenology at current and future facilities.

hep-ph↗
arXiv2026

Tensor Decomposition for Energy-Momentum Correlation Functions

We establish the general functional form of the energy-momentum-tensor two-point function in Euclidean coordinate space at zero and finite temperature. The full correlation function is first decomposed into its fundamental tensorial structures based on the remaining rotational symmetry. We use energy-momentum conservation to derive differential relations between the resulting component functions. Using these constraints, the full set of component functions of the correlator can finally be represented in the form of a smaller set of spectral functions. Finally, we show how to use these techniques for more efficient future lattice investigations.

hep-ph↗
arXiv2026

Why fluctuations of conserved charges in the confining regime above $T_{ch}$ behave as if the quarks were free?

Some cumulants of the fluctuations of conserved charges soon above the chiral crossover behave as if the quarks were free. This was taken by many as evidence of deconfinement. At the same temperatures the mesonic correlators reveal the chiral spin and SU(4) symmetries, indicating that the propagating degrees of freedom are massless quarks connected into color singlets by the chromoelectric confining string. These correlators are qualitatively different from the free quark gas. Here we clarify the reason for the difference. The conserved quark number densities do not propagate in time but do propagate in spatial directions. The mesonic propagators calculated in full QCD differ radically from the free quark loop (quark gas) above T_ch. In contrast, the quark number density spatial propagator in full QCD at T > 220 MeV is very close to the free quark loop. In other words, the conserved charges do not see confinement, in contrast to the mesonic correlators. This is consistent with the well understood quark-hadron duality at T=0 in e^+e^- -> hadrons, where at invariant masses above 2 GeV the cross-section in the confining regime is represented by the free quark loop plus small perturbative corrections. All these features above T_ch but below the deconfinement temperature T_d can be combined within the following microscopic picture of the stringy fluid matter. It is a medium of the overlapping strongly interacting color singlet clusters. The quark interchanges between the clusters, required by Paili principle, make the quarks quasifree, which is reflected in fluctuations of conserved charges.

hep-ph↗