arXiv subjects

Agnieszka Grzelinska

Publications and source records attributed to Agnieszka Grzelinska.

12 recordsLinked to original sources

arXiv2011

PHOKHARA 7.0 Monte Carlo generator: the narrow resonances implementation and new pion and kaon form factors

Experiments at high luminosity electron-positron colliders allow to study the kaon and the pion form factors in the time-like region up to high energies. Also the kaon and the pion pair production at and around the narrow resonances J/psi and psi(2S) can be investigated, with the interference between electromagnetic and hadronic amplitudes as one of the most interesting phenomenas. Parameterisations of charged and neutral kaon as well as pion form factors, which lead to an improved description of the data in the region of large invariant masses of the meson pair, are presented. They are implemented into the Monte Carlo generator PHOKHARA, together with the hadronic couplings of charged and neutral kaons to J/psi and psi(2S). The physics case as well as details of the implementation are discussed.

hep-ph↗

arXiv2010

Narrow resonances studies with the radiative return method

Using the radiative return method, experiments at high luminosity electron-positron colliders allow to explore the kaon and the pion form factors in the time-like region up to fairly high energies. This opens the possibility to study kaon and pion pair production at and around the narrow resonances J/psi and psi(2S) and explore the interference between electromagnetic and hadronic amplitudes. Parameterizations of charged and neutral kaon as well as pion form factors are derived, which lead to an improved description of the data in the region of large invariant masses of the meson pair. These form factors are combined with the hadronic couplings of charged and neutral kaons to J/psi and psi(2S) and implemented into the Monte Carlo generator PHOKHARA, which is now, for the first time, able to simulate the production of narrow resonances and their decay into kaon, pion and muon pairs.

hep-ph↗

arXiv2008

Status of Phokhara

A review of the status of the Monte Carlo event generator PHOKHARA, developed for experiments using the radiative return method. The four-pion production in electron-positron annihilation and in tau-lepton decays and the narrow resonances studies are described.

hep-ph↗

arXiv2007

New developments in PHOKHARA Monte Carlo generator

The present status of the physics program, which led to the development of the Monte Carlo event generator PHOKHARA is described. The possibility of using the radiative return method in various aspects of hadronic physics, from the measurement of the hadronic cross section, to detailed investigations of the hadronic dynamics is emphasized. New results are presented showing how to measure baryon form factors using the knowledge of their spin in baryon-antibaryon production with subsequent decay.

hep-ph↗

arXiv2007

Radiative return physics program within EURIDICE network

A short review of both theoretical and experimental aspects of the radiative return method is presented with the emphasize on the results obtained within the EURIDICE network. It is shown that the method gives not only possibility of an independent from the scan method measurement of the hadronic cross section, but also can provide information concerning details of the hadronic interactions.

hep-ph↗

arXiv2007

Spin asymmetries and correlations in lambda-pair production through the radiative return method

Exclusive baryon pair production through the radiative return is a unique tool to determine the electric and the magnetic form factors in the timelike region over a wide range of energies. The decay of lambda-baryons into p + pi- can be used to measure their spin and to analyze spin-spin correlations in the antilambda-lambda system. We evaluate the spin dependent hadronic tensor, which describes this reaction, calculate the corresponding cross section for e+e- -> antilambda lambda and e+e- -> antilambda lambda gamma with subsequent decays of lambda and antilambda and present a compact formula for the correlated distribution. We demonstrate that the relative phase between the electric and the magnetic form factor can be determined in this analysis by considering single spin asymmetries and correlated decay distributions. The reaction is implemented in the event generator PHOKHARA. It is demonstrated that the relative phase can be measured with the event sample presently accumulated at B-factories.

hep-ph↗

arXiv2006

Electron-positron annihilation into three pions and the radiative return

The Monte Carlo event generator PHOKHARA, which simulates hadron and muon production at electron-positron colliders through radiative return, has been extended to final states with three pions. A model for the form factor based on generalized vector dominance has been employed, which is consistent with presently available experimental observations.

hep-ph↗

arXiv2005

The radiative return at phi- and B-factories: small-angle photon emission at next to leading order

The radiative return offers the unique possibility for a measurement of the cross section of electron--positron annihilation into hadrons over a wide range of energies. The large luminosity of present phi- and B-factories easily compensates for the additional factor of alpha due to the emission of a hard photon. Final states with photons at large angles can be easily identified. The rate for events with collinear photons, however, is enhanced by a large logarithm and allows, in particular at lower energies, for a complementary measurement. The Monte Carlo generator PHOKHARA, which includes next to leading order corrections from virtual and real photon emission, has been extended from large photon angles into the collinear region, using recent results for the virtual corrections. In addition, the present version includes final state radiation for muon and pion pair production and final states with four pions. Implications for the experimental analysis at three typical energies, 1.02, 4 and 10.6 GeV, are presented: the magnitude of these new corrections is studied, possibilities for the separation of initial and final state radiation are proposed, and the differences with respect to the previous treatment based on structure functions are investigated.

hep-ph↗

arXiv2005

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

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.

hep-ph↗

arXiv2004

Hadronic cross section from radiative return

The impact of final-state radiation (FSR) on the radiative return method for the extraction of the e+e- hadronic cross section is discussed in detail and experimental tests of the model dependence of FSR are proposed for the pi+pi- hadronic final state.

hep-ph↗

arXiv2004

The radiative return at phi- and B-factories: FSR at next-to-leading order

The measurement of the pion form factor and, more generally, of the cross section for electron--positron annihilation into hadrons through the radiative return has become an important task for high luminosity colliders such as the $Φ$- or $B$-meson factories. For detailed understanding and analysis of this reaction, the construction of a Monte Carlo program, PHOKHARA, has been undertaken. Version 2.0 was based on a next-to-leading order (NLO) treatment of the corrections from initial-state radiation (ISR). In the present paper a further extension of PHOKHARA (version 3.0) is described, which incorporates NLO corrections to final-state radiation (FSR). The impact of combined ISR and FSR on various distributions is investigated and methods are presented, which will allow the extraction of the form factor, and even give access to inclusive photon emission due to FSR. The dependence of the results on the model for FSR is discussed and the impact of this contribution on the anomalous magnetic moment of the muon is evaluated.

hep-ph↗

arXiv2003

FSR at leading and next-to-leading order in the radiative return at meson factories

The impact of final-state radiation (FSR) on the radiative return method for the extraction of the e+e- hadronic cross section is discussed in detail. Possible experimental tests of the model dependence of FSR are proposed for the pi+pi- hadronic final state. The importance of the (pi+pi-photon) final state contribution to the muon anomalous magnetic moment is investigated, and a method based on the radiative return is proposed to extract these contributions from data.

hep-ph↗