Search results for "Particle physics"

Lepton-hadron correlations to O(αs2) in (2+1) jet production processes at hera

1992

Abstract We give a qualitative account of some of the technical features that go into the calculation of the one-loop improved O(αs2) (2+1) jet production rates in deep inelastic scattering which was completed only recently. We present some numerical results on (2+1) jet production with an emphasis on lepton-hadron correlation effects by exhibiting the contribution of the longitudinal structure function.

Search for the decay KS → π0γγ

2003

Abstract A search for the decay K S → π 0 γγ has been made using the NA48 detector at the CERN SPS. Using data collected in 1999 during a 40-hour run with a high-intensity K S beam, an upper limit for the branching ratio BR ( K S → π 0 γγ , z ⩾0.2) −7 has been obtained at 90% confidence level, where z = m γγ 2 / m K 0 2 .

Measurement of the decay KL→e+e−γγ

1998

The full data set of the NA31 experiment at CERN has been used to analyse the decay mode KOL → e+ e-γγ. A signal of 47 events has been observed with an estimated background of 6.9 events. The total number of kaon decays in the decay volume was determined to be (2.1 ± 0.1stat) · 109. This corresponds to a branching ratio of (8.0 ± 1.5+1.4-1.2)· 10-7. © 1998 Published by Elsevier Science B.V.

Study of the rare Bs0 and B0 decays into the π+π−μ+μ− final state

2015

A search for the rare decays B0s→π+π−μ+μ− and B0→π+π−μ+μ− is performed in a data set corresponding to an integrated luminosity of 3.0 fb−1 collected by the LHCb detector in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. Decay candidates with pion pairs that have invariant mass in the range 0.5-1.3 GeV/c2 and with muon pairs that do not originate from a resonance are considered. The first observation of the decay B0s→π+π−μ+μ− and the first evidence of the decay B0→π+π−μ+μ− are obtained and the branching fractions are measured to be B(B0s→π+π−μ+μ−)=(8.6±1.5(stat)±0.7(syst)±0.7(norm))×10−8 and B(B0→π+π−μ+μ−)=(2.11±0.51(stat)±0.15(syst)±0.16(norm))×10−8, where the third unc…

Heavy flavour production and fragmentation

2001

We review theoretical and experimental results relevant to charm and bottom physics. In particular, we consider charmonium and open heavy-flavour production at Tevatron, LEP and HERA colliders, and in heavy-ion scattering. We study the prospect of future b-physics measurement at the LHC with the ATLAS and CMS detectors.

First observation of strong OZI rule violation in πN interactions

1996

The data of the CERN WA56 experiment that triggered the fast proton produced in the $\pi^{+}p$ and $\pi^{-}p$ interactions at beam momenta 20 GeV/c and 12 GeV/c, respectively, are used to analyse the final states $ p_{f} \phi (\omega)\pi^{\pm}$. A large excess (up to two orders of magnitude) of the $\phi/\omega$ cross sections ratio over the OZI prediction is observed.

Towards high-precision mass measurements on 74Rb for a test of the CVC hypothesis and the unitarity of the CKM matrix

2004

At the highest possible precisions, atomic-mass measurements can be used to perform fundamental studies. Examples for such studies are a check of the conserved-vector-current (CVC) hypothesis and the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, both postulates of the Standard Model. The comparative half-lives Ft of superallowed β decays constitute the nuclear-physics access to these tests. The Q value of the β decay of 74 Rb, one of the three experimentally accessible parameters that enter into the Ft values, has been measured with the ISOLTRAP experiment at ISOLDE/CERN. The ultimate mass precision requirement and the way to achieve it are outlined.

Neutrino mean free path in hot neutron matter with skyrme interactions

1999

Formation of Slow Heavy Mesons in Nuclei

2010

Abstract We study ϕ meson production in the C 12 ( p ¯ , ϕ ) reaction at p p ¯ = 1.3 GeV/c . We also discuss the interest in and the difficulties of studying heavy meson-nucleus systems.

Measurement of the Lifetime of Neutral Charmed Mesons

1984

Abstract The lifetime of neutral charmed particles photoproduced in emulsion has been measured. The lifetime value presented here was obtained from a sample of 22D 0 mesons, 18 of which have their charmed partner seen in emulsion. The sample is essentially background-free. The result obtained is τ D 0 =(2.11 +1.21 -0.63 )×10 13 s The D 0 mass derived from 8 3C events is m D 0 = 1856 ± 36 MeV/ c 2 .