Precise tests of low energy QCD from Ke4 decay properties

We report results from the analysis of the K\ub1 \u2192 pi+ pi 12 e\ub1 \u3bd (Ke4 ) decay by the NA48/2 collaboration at the CERN SPS, based on the total statistics of 1.13 million decays collected in 2003\u20132004. The hadronic form factors in the S- and P-wave and their variation with energy are obtained. The phase difference between the S- and P-wave states of the pion pion system is accurately measured and allows a precise determination of a00 and a02 , the I = 0 and I = 2 S-wave pion pion scattering lengths: a00 = 0.2220 \ub1 0.0128stat \ub1 0.0050syst \ub1 0.0037th , a02 = 120.0432 \ub1 0.0086stat \ub1 0.0034syst \ub1 0.0028th . Combination of this result with the other NA48/2 measurement obtained in the study of K\ub1 \u2192 pi0 pi0 pi\ub1 decays brings an improved determination of a00 and the first precise experimental measurement of a02, providing a stringent test ofChiral Perturbation Theory predictions and lattice QCD calculations. Using constraints based on analyticity and chiral symmetry, even more precise values are obtained: a00 = 0.2196 \ub1 0.0028stat \ub1 0.0020syst and a02 = 120.0444 \ub10.0007stat \ub1 0.0005syst \ub1 0.0008ChPT

Search for the dark photon in pi0 decays

Abstract A sample of 1.69 7 10 7 fully reconstructed \u3c0 0 \u2192 \u3b3 e + e 12 decay candidates collected by the NA48/2 experiment at \{CERN\} in 2003\u20132004 is analyzed to search for the dark photon ( A \u2032 ) production in the \u3c0 0 \u2192 \u3b3 A \u2032 decay followed by the prompt A \u2032 \u2192 e + e 12 decay. No signal is observed, and an exclusion region in the plane of the dark photon mass m A \u2032 and mixing parameter \u3b5 2 is established. The obtained upper limits on \u3b5 2 are more stringent than the previous limits in the mass range 9 \ua0 MeV / c 2 < m A \u2032 < 70 \ua0 MeV / c 2 . The NA48/2 sensitivity to the dark photon production in the K \ub1 \u2192 \u3c0 \ub1 A \u2032 decay is also evaluated

Searches for lepton number violation and resonances in K\ub1\ua0\u2192\ua0\u3c0\u3bc\u3bc decays

The NA48/2 experiment at CERN collected a large sample of charged kaon decays to final states with multiple charged particles in 2003\u20132004. A new upper limit on the rate of the lepton number violating decay K\ub1\u2192\u3c0 13\u3bc\ub1\u3bc\ub1 is reported: B(K\ub1\u2192\u3c0 13\u3bc\ub1\u3bc\ub1)<8.6 710 1211 at 90% CL. Searches for two-body resonances X in K\ub1\u2192\u3c0\u3bc\u3bc decays (such as heavy neutral leptons N4 and inflatons \u3c7) are also presented. In the absence of signals, upper limits are set on the products of branching fractions B(K\ub1\u2192\u3bc\ub1N4)B(N4\u2192\u3c0\u3bc) and B(K\ub1\u2192\u3c0\ub1X)B(X\u2192\u3bc+\u3bc 12) for ranges of assumed resonance masses and lifetimes. The limits are in the (10 1211,10 129) range for resonance lifetimes below 100 ps. \ua9 2017 The Author(s

Measurements of charged kaon semileptonic decay branching fractions K-+/- -> pi(0)mu(+/-)v and K-+/- -> pi(0)e(+/-)v and their ratio (vol 50, pg 329, 2007) RID A-4071-2012

In an earlier paper [1], the background for K-e3 was over estimated due to an erroneous calculation of the electron identification efficiency. The correct ratios of the partial widths involving this channel are R-Ke3/K2 pi = 0.2470 +/- 0.0009 (stat) +/- 0.0004 (syst) and R-K mu 3/Ke3 = 0.663 +/- 0.003 (stat) +/- 0.001 (syst). Assuming the PDG value [2] for the K-2 pi branching ratio, the measured branching fraction of Br (K-e3) continues to exceed the current PDG value [2]. The extracted value of |V-us|f(+)(0) is in agreement with the CKM unitary prediction; thus, our conclusions in [1] do not change

Searches for lepton number violation and resonances in K+- -> pi mu mu decays

The NA48/2 experiment at CERN collected a large sample of charged kaon decays to final states with multiple charged particles in 2003\ue2\u80\u932004. A new upper limit on the rate of the lepton number violating decay K\uc2\ub1\ue2\u86\u92\ucf\u80\ue2\u88\u93\uce\ubc\uc2\ub1\uce\ubc\uc2\ub1is reported: B(K\uc2\ub1\ue2\u86\u92\ucf\u80\ue2\u88\u93\uce\ubc\uc2\ub1\uce\ubc\uc2\ub1)<8.6\uc3\u9710\ue2\u88\u9211at 90% CL. Searches for two-body resonances X in K\uc2\ub1\ue2\u86\u92\ucf\u80\uce\ubc\uce\ubc decays (such as heavy neutral leptons N4and inflatons \ucf\u87) are also presented. In the absence of signals, upper limits are set on the products of branching fractions B(K\uc2\ub1\ue2\u86\u92\uce\ubc\uc2\ub1N4)B(N4\ue2\u86\u92\ucf\u80\uce\ubc) and B(K\uc2\ub1\ue2\u86\u92\ucf\u80\uc2\ub1X)B(X\ue2\u86\u92\uce\ubc+\uce\ubc\ue2\u88\u92) for ranges of assumed resonance masses and lifetimes. The limits are in the (10\ue2\u88\u9211,10\ue2\u88\u929) range for resonance lifetimes below 100 ps

Detailed study of the K\ub1 \u2192 \u3c0 0\u3c00e\ub1\u3bd (Ke4 00) decay properties

A sample of 65210 K\ub1 \u2192 \u3c00\u3c00e\ub1\u3bd (Ke4 00) decay candidates with 1% background contamination has been collected in 2003-2004 by the NA48/2 collaboration at the CERN SPS. A study of the differential rate provides the first measurement of the hadronic form factor variation in the plane (M\u3c0\u3c0 2, Me\u3bd 2) and brings evidence for a cusp-like structure in the distribution of the squared \u3c00\u3c00 invariant mass around (Formula Presented). Exploiting a model independent description of this form factor, the branching ratio, inclusive of radiative decays, is obtained using the K\ub1 \u2192 \u3c00\u3c00\u3c0\ub1 decay mode as normalization. It is measured to be BR(Ke4 00) = (2.552 \ub1 0.010stat \ub1 0.010syst \ub1 0.032ext) 7 10 125, which improves the current world average precision by an order of magnitude while the 1.4% relative precision is dominated by the external uncertainty from the normalization mode. A comparison with the properties of the corresponding mode involving a \u3c0+\u3c0 12 pair (Ke4 + 12) is also presented

High precision measurement of the form factors of the semileptonic decays K\ub1 \u2192 \u3c00l\ub1\u3bd (Kl3) in NA48/2

The data collected by NA48/2 in 2003-2004 allowed several precise measurements in the charged kaon decay sector. In this paper we present the results obtained using a sample of 2.5 7106 K\ub1 \u2192 \u3c00\u3bc\ub1\u3bd (K\u3bc3) and 4.0 7106 K 7 \u2192 \u3c00l \ub1\u3bd (Ke3) events, collected in 2004 using a minimal trigger configuration. This unbiassed sample of kaon decays allows a high precision measurement of the semileptonic form factors. \ua9 Copyright owned by the author(s)

A new measurement of the K \ub1 \u2192 \u3c0 \ub1\u3b3\u3b3 decay at the NA48/2 experiment

The NA48/2 experiment at CERN collected two data samples with minimum bias trigger conditions in 2003 and 2004. A measurement of the rate and dynamic properties of the rare decay K \ub1 \u2192 \u3c0 \ub1\u3b3\u3b3 from these data sets based on 149 decay candidates with an estimated background of 15.5 \ub1 0.7 events is reported. The model-independent branching ratio in the kinematic range z=(m\u3b3\u3b3/mK)2&gt;0.2 is measured to be BMI(z&gt;0.2)=(0.877\ub10.089) 710-6, and the branching ratio in the full kinematic range assuming a particular Chiral Perturbation Theory description to be B(K\u3c0\u3b3\u3b3)=(0.910\ub10.075) 710-6. \ua9 2014 The Authors

The beam and detector for the NA48 neutral kaon CP violation experiment at CERN

The beam and detector, used for the NA48 experiment, devoted to the measurement of Re(epsilon'/epsilon) and for the NA48/1 experiment onrare K S and neutral hyperon decays, are described

The AlpArray Seismic Network: A Large-Scale European Experiment to Image the Alpine Orogen

The AlpArray programme is a multinational, European consortium to advance our understanding of orogenesis and its relationship to mantle dynamics, plate reorganizations, surface processes and seismic hazard in the Alps-Apennines-Carpathians-Dinarides orogenic system. The AlpArray Seismic Network has been deployed with contributions from 36 institutions from 11 countries to map physical properties of the lithosphere and asthenosphere in 3D and thus to obtain new, high-resolution geophysical images of structures from the surface down to the base of the mantle transition zone. With over 600 broadband stations operated for 2 years, this seismic experiment is one of the largest simultaneously operated seismological networks in the academic domain, employing hexagonal coverage with station spacing at less than 52 km. This dense and regularly spaced experiment is made possible by the coordinated coeval deployment of temporary stations from numerous national pools, including ocean-bottom seismometers, which were funded by different national agencies. They combine with permanent networks, which also required the cooperation of many different operators. Together these stations ultimately fill coverage gaps. Following a short overview of previous large-scale seismological experiments in the Alpine region, we here present the goals, construction, deployment, characteristics and data management of the AlpArray Seismic Network, which will provide data that is expected to be unprecedented in quality to image the complex Alpine mountains at depth