Filippo Ceradini

Further evidence for production of electrons with small transverse momenta in pp collisions

A new measurement of prompt lepton production at small transverse momenta in pp collisions at the ISR, for s = 53 GeV, is presented. The cπ ratio, which is about 10−4 for pT > 1 GeV/c, rises rapidly as pT goes to smaller values, confirming our original results. The data are consistent with equality between the numbers of e+ and e− produced in each transverse momentum interval.

A study of kinematical correlations between charmed particles produced in π-Cu interactions at s=26 GeV

Abstract A sample of 475 events, in which two charmed-particle decays are observed, is analyzed to determine distributions of two-particle kinematic variables. One charmed particle with x F > 0 is fully reconstructed and the other is at least partially recontructed. The distributions of Δo and p T 2 are compared with a next-to-leading order QCD calculation.

Search for D0-meson production in p-p interactions at a centre-of-mass energy of 53 GeV

Abstract A search for D(1.87) mesons produced at x ∼ 0.1 at the CERN ISR gave a null result. Cross-section upper limits of 9 μb and 8 μb at the 95% confidence level were measured for the processes p + p → D 0 + X, D 0 → K − + π + , and p + p → D 0 + X , D 0 → K + + π − , respectively. Producton of f 0 (1270) was observed with a cross-section of 1.9 ± 0.4 mb.

Search for the decay D0 → μ+μ−

Abstract We have searched for the decay D 0 → μ + μ − among 1.25 × 10 5 μ + μ − pairs produced by 350 GeV/ c π − particles interacting in copper and tungsten targets. Using a high-resolution silicon-microstrip detector followed by a large-acceptance magnetic spectrometer and a muon filter we are able to discriminate between prompt and non-prompt muons and to measure dimuon masses. No candidate compatible with a D 0 → μ + μ − decay has been found, allowing us to set an upper limit on the branching fraction B( D 0 → μ + μ − ) of 7.6 × 10 −6 at the 90% confidence level.

Limits on e±μ∓ production in pp collisions at the CERN ISR

Abstract A search for the reaction p+p → e ± μ ± +X at the CERN ISR gave no evidence for this process. Upper limits for e ± μ ∓ /e +- are presented and are related to the branching fraction for leptonic decay of D(1.87).

Upper limit for DD production in pp interactions at C.M. energy of 55 GeV

Abstract From a search for e ± μ ± production at the CERN ISR an upper limit of 0.92 μ b (95% confidence limit) has been inferred for σ · B e · B μ for the reaction p + p → D + D + X at √s of 55 GeV .

Measurement of the distributions of event-by-event flow harmonics in Pb+Pb collisions at √sNN = 2.76 TeV with the ATLAS detector

The distributions of event-by-event harmonic flow coefficients vn for n =2–4 are measured in √ sNN = 2.76 TeV Pb+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using charged particles with transverse momentum pT > 0.5 GeV and in the pseudorapidity range |η| < 2.5 in a dataset of approximately 7 μb−1 recorded in 2010. The shapes of the vn distributions are described by a two-dimensional Gaussian function for the underlying flow vector in central collisions for v2 and over most of the measured centrality range for v3 and v4. Significant deviations from this function are observed for v2 in mid-central and peripheral collisions, and a small deviation is observed for v3 in mid-central collisions. It is shown that the commonly used multi-particle cumulants are insensitive to the deviations for v2. The vn distributions are also measured independently for charged particles with 0.5 < pT < 1 GeV and pT > 1 GeV. When these distributions are rescaled to the same mean values, the adjusted shapes are found to be nearly the same for these two pT ranges. The vn distributions are compared with the eccentricity distributions from two models for the initial collision geometry: a Glauber model and a model that includes corrections to the initial geometry due to gluon saturation effects. Both models fail to describe the experimental data consistently over most of the measured centrality range. Prepared for submission to JHEP Measurement of the distributions of event-by-event flow harmonics in lead–lead collisions at √ s NN = 2.76 TeV with the ATLAS detector at the LHC The ATLAS Collaboration Abstract: The distributions of event-by-event harmonic flow coefficients vn for n =2– 4 are measured in √ sNN = 2.76 TeV Pb+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using charged particles with transverse momentum pT > 0.5 GeV and in the pseudorapidity range |η| < 2.5 in a dataset of approximately 7 μb−1 recorded in 2010. The shapes of the vn distributions are described by a twodimensional Gaussian function for the underlying flow vector in central collisions for v2 and over most of the measured centrality range for v3 and v4. Significant deviations from this function are observed for v2 in mid-central and peripheral collisions, and a small deviation is observed for v3 in mid-central collisions. It is shown that the commonly used multi-particle cumulants are insensitive to the deviations for v2. The vn distributions are also measured independently for charged particles with 0.5 < pT < 1 GeV and pT > 1 GeV. When these distributions are rescaled to the same mean values, the adjusted shapes are found to be nearly the same for these two pT ranges. The vn distributions are compared with the eccentricity distributions from two models for the initial collision geometry: a Glauber model and a model that includes corrections to the initial geometry due to gluon saturation effects. Both models fail to describe the experimental data consistently over most of the measured centrality range. The distributions of event-by-event harmonic flow coefficients vn for n =2– 4 are measured in √ sNN = 2.76 TeV Pb+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using charged particles with transverse momentum pT > 0.5 GeV and in the pseudorapidity range |η| < 2.5 in a dataset of approximately 7 μb−1 recorded in 2010. The shapes of the vn distributions are described by a twodimensional Gaussian function for the underlying flow vector in central collisions for v2 and over most of the measured centrality range for v3 and v4. Significant deviations from this function are observed for v2 in mid-central and peripheral collisions, and a small deviation is observed for v3 in mid-central collisions. It is shown that the commonly used multi-particle cumulants are insensitive to the deviations for v2. The vn distributions are also measured independently for charged particles with 0.5 < pT < 1 GeV and pT > 1 GeV. When these distributions are rescaled to the same mean values, the adjusted shapes are found to be nearly the same for these two pT ranges. The vn distributions are compared with the eccentricity distributions from two models for the initial collision geometry: a Glauber model and a model that includes corrections to the initial geometry due to gluon saturation effects. Both models fail to describe the experimental data consistently over most of the measured centrality range.A bstractThe distributions of event-by-event harmonic flow coefficients vn for n = 2- 4 are measured in

Construction and Performance of a High Granularity Calorimeter

\sqrt{{{s_{NN }}}}

Construction and performances of an high granularity calorimeter

= 2.76 TeV Pb + Pb collisions using the ATLAS detector at the LHC. The measurements are performed using charged particles with transverse momentum pT> 0.5 GeV and in the pseudorapidity range |η| < 2.5 in a dataset of approximately 7 μb−1 recorded in 2010. The shapes of the vn distributions suggest that the associated flow vectors are described by a two-dimensional Gaussian function in central collisions for v2 and over most of the measured centrality range for v3 and v4. Significant deviations from this function are observed for v2 in mid-central and peripheral collisions, and a small deviation is observed for v3 in mid-central collisions. In order to be sensitive to these deviations, it is shown that the commonly used multi-particle cumulants, involving four particles or more, need to be measured with a precision better than a few percent. The vn distributions are also measured independently for charged particles with 0.5 < pT< 1 GeV and pT> 1 GeV. When these distributions are rescaled to the same mean values, the adjusted shapes are found to be nearly the same for these two pT ranges. The vn distributions are compared with the eccentricity distributions from two models for the initial collision geometry: a Glauber model and a model that includes corrections to the initial geometry due to gluon saturation effects. Both models fail to describe the experimental data consistently over most of the measured centrality range.

Measurement of the K-L ->pi mu nu form factor parameters with the KLOE detector RID C-6238-2011 RID D-2250-2011 RID G-6301-2011 RID C-9722-2011 RID D-2615-2009 RID A-6640-2010

We describe the realization and performance of a prototype high granularity calorimeter built with lead and scintillating fibers. We describe the calorimeter construction and show cosmic ray and electron test beam results obtained with a custom-designed trigger.