Search results for "Particle physics"

f1(1285) decays into a0(980)π0, f0(980)π0 and isospin breaking

2016

We evaluate the decay width for the processes f1(1285) → π0a0(980) and f1(1285) → π0f0(980) taking into account that all three resonances are dynamically generated from the meson-meson interaction, the f1(1285) from K*K¯+cc and the a0 (980), f0(980) from πη, KK¯ and ππ, KK¯ respectively. We use a triangular mechanism similar to that of the η(1405)→ππη, which provides a decay width for f1 (1285) → π0a0 (980) with a branching fraction of the order of 30%, in agreement with experiment. At the same time we evaluate the decay width for the isospin forbidden f1(1285) → π0 f0(980), which appears when we consider different masses for the charged and neutral kaons, and show that it is much more supp…

Analysis of the Lepton Mixing Matrix from Neutrino Oscillation Experiments

1988

An analysis of experimental results in the framework of simultaneous oscillations of three neutrino flavours is used, in a combined fit, to constrain the elements of the 3×3 unitary lepton mixing matrix and to obtain limits on the three lepton mixing angles αeμ αeτ and αμτ. No evidence for mixing is found.

Lepton-hadron correlations to $$\mathcal{O}(\alpha _s^2 )$$ in (2+1) jet production at electron-proton colliders

1992

We present one-loop corrected\(\mathcal{O}(\alpha _s^2 )\) results on the four parity-conserving structure functions that describe deep inelastic (2+1)-jet production at high energy electron-proton colliders.

Kaon physics at the CERN-SPS

2015

The NA48/2 and NA62 collaborations report on recent results, current status, and prospects of kaon physics at the CERN-SPS. The NA62 collaborations aims to measure the decay [Formula: see text] with an uncertainty of 10% or better. The NA62 detector and preliminary results from a pilot run in 2014 are presented. In addition, recent results of the NA48/2 collaboration are reported. A search for Dark Photons has been performed in [Formula: see text] decays via the kaon decays [Formula: see text] and [Formula: see text]. No dark photon signal was observed and new upper limits on the mixing parameter [Formula: see text] and the dark photon mass were computed. We also report the first observati…

Electromagnetic interactions of nucleons and nuclei at low energy and momentum transfer

2005

Tau neutrino mass from semileptonic decays

1981

The semileptonic three particle decays of the tau provide determinations of the tau neutrino mass. The shift of the maximal energy of the observable final state particles islinear in the neutrino mass. The endpoint energy of the pion and a partially integrated decay rate in τ → πωvτ and τ → πρVτ are sensitive to a neutrino mass smaller than 100 MeV. Thus, the present bound on\(m_{v_\tau } \) can significantly be improved.

Measurement of the π0→e+e−γ Dalitz decay at the Mainz Microtron

2017

The Dalitz decay π0→e+e−γ has been measured in the γp→π0p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The value obtained for the slope parameter of the π0 electromagnetic transition form factor, aπ=0.030±0.010tot, is in agreement with existing measurements of this decay and with recent theoretical calculations. The uncertainty obtained in the value of aπ is lower than in previous results based on the π0→e+e−γ decay.

UNQUENCHED QUARK MODEL DESCRIPTION OF CHARMONIUM

2011

We show that the charmonium spectrum may be reproduced to a good precision by means of a semirelativistic quark model approach based on a universal static potential effectively incorporating effects from sea quark-antiquark pairs. Detailed predictions for upcoming data are derived.

Measurement ofBc+Production in Proton-Proton Collisions ats=8  TeV

2015

Production of B+c mesons in proton-proton collisions at a center-of-mass energy of 8~TeV is studied with data corresponding to an integrated luminosity of 2.0 fb−1 recorded by the LHCb experiment. The ratio of production cross-sections times branching fractions between the B+c→J/ψπ+ and B+→J/ψK+ decays is measured as a function of transverse momentum and rapidity in the regions 0<pT<20 GeV/c and 2.0<y<4.5. The ratio integrated within this kinematic range is measured to be (0.683±0.018±0.009)%, where the first uncertainty is statistical and the second systematic.

CHARMONIUM: X(3872) AND BEYOND

2011

We analyze the spectrum of charmonium above the threshold for the production of D mesons. Several recent intriguing experimental data have reopen the interest on charmonium spectroscopy and they deserve an special attention. We focus our study on the X(3872) and the possible existence of charged states contributing to the spectrum of charmonium