arXiv subjects

Rene Unterdorfer

Publications and source records attributed to Rene Unterdorfer.

3 recordsLinked to original sources

arXiv2008

On the Radiative Pion Decay

A reanalysis of the radiative pion decay together with the calculation of the radiative corrections within chiral perturbation theory (CHPT) is performed. The amplitude of this decay contains an inner Bremsstrahlung contribution and a structure-dependent part that are both accessible in experiments. In order to obtain a reliable estimate of the hadronic contributions we combine the CHPT result with a large-N_C expansion and experimental data on other decays, which makes it possible to determine the occurring coupling constants.

hep-ph↗

arXiv2004

Calorimetric transverse energy-energy correlations as a probe of jet quenching

The sensitivity of calorimetric energy-energy correlation function to the medium-induced energy loss of fast partons in high multiplicity heavy ion interactions is demonstrated at the appropriate selection of events for the analysis, namely, the availability of one high-pt jet in an event at least and using the procedure of ``thermal'' background subtraction. Without jet trigger this correlation function manifests the global structure of transverse energy flux: the correlator is isotropic for central collisions, and for non-central collisions it is sensitive to the azimuthal anisotropy of energy flow reproducing its Fourier harmonics but with the coefficients squared.

hep-ph↗

arXiv2003

On the short-distance constraints from K_{L,S} -> mu^+ mu^-

Motivated by new precise results on several $K_L$ decays, sensitive to the ${K_L \to γγ}$ form factor, we present a new analysis of the $K_L\to μ^+μ^-$ long-distance amplitude based on a semi-phenomenological approach. Particular attention is devoted to the evaluation of the uncertainties of this method and to the comparison with alternative approaches. Our main result is a conservative upper bound of $2.5 \times 10^{-9}$ on $B(K_L \to μ^+ μ^-)_{\rm short}$, which is compatible with the SM expectation and which provides significant constraints on new-physics scenarios. The possibility to extract an independent short-distance information from future searches on $K_S \to μ^+ μ^-$ is also briefly discussed.

hep-ph↗