Search results for " nucleare"
showing 10 items of 82 documents
Searches for anisotropies in the arrival directions of the highest energy cosmic rays detected by the Pierre Auger Observatory
2015
We analyze the distribution of arrival directions of ultra-high energy cosmic rays recorded at the Pierre Auger Observatory in 10 years of operation. The data set, about three times larger than that used in earlier studies, includes arrival directions with zenith angles up to $80^\circ$, thus covering from $-90^\circ$ to $+45^\circ$ in declination. After updating the fraction of events correlating with the active galactic nuclei (AGNs) in the V��ron-Cetty and V��ron catalog, we subject the arrival directions of the data with energies in excess of 40 EeV to different tests for anisotropy. We search for localized excess fluxes and for self-clustering of event directions at angular scales up t…
Search for weakly decaying b -flavored pentaquarks
2018
Investigations of the existence of pentaquark states containing a single $b$ (anti)quark decaying weakly into four specific final states J/$\psi K^+\pi^- p$, J/$\psi K^- \pi^- p$, J/$\psi K^- \pi^+ p$, and $J/\psi \phi (1020) p$ are reported. The data sample corresponds to an integrated luminosity of 3.0/fb in 7 and 8 TeV pp collisions acquired with the LHCb detector. Signals are not observed and upper limits are set on the product of the production cross section times branching fraction with respect to that of the $\Lambda_b$.
Searches for lepton number violating $K^+$ decays
2019
The NA62 experiment at CERN reports a search for the lepton number violating decays K+ -> pi(-)e(+)e(+) and K+ -> pi(-)mu(+)mu(+) using a data sample collected in 2017. No signals are observed, and upper limits on the branching fractions of these decays of 2.2 x 10(-10) and 4.2 x 10(-11) are obtained, respectively, at 90% confidence level. These upper limits improve on previously reported measurements by factors of 3 and 2, respectively.
I vari modi del DNA di “parlare” ai viventi fra ciò che già è noto e nuove scoperte
2018
A sessant’anni da quando Francis Crick enunciò il “dogma centrale della biologia molecolare” molte scoperte e nuove frontiere si sono avvicendate sulla questione “funzionale” di un genoma, cioè di come un DNA “parla” ai viventi. Oggi è abbastanza noto come un genoma “è”, ed occuparsi solo di questa questione strutturale ormai è sicuramente molto riduttivo, almeno sicuramente per quello umano. È invece il goal standard di questi anni scoprire come e quando un genoma si esprime, come funzio-nalmente traduce il suo messaggio rendendo questo visibile nei fe-notipi dei viventi, a prescindere dalla sua sequenza primaria di basi azotate. Ne consegue che il codice genetico, ancora valido e quasi un…
TAGS measurements for neutrino physics and applications
2017
En la actualidad un gran número de temas de interés en Física Nuclear continúan planteando interrogantes fundamentales. Una de las fuentes de información más esclarecedoras es el proceso de la desintegración beta. Gracias al estudio experimental de este fenómeno en núcleos alejados de la estabilidad, es posible extraer valiosa información sobre estructura nuclear. En esa línea, esta tesis se centra en la determinación de las intensidades beta que pueblan los estados excitados del núcleo hijo en la desintegración beta de núcleos exóticos de gran interés. Para ello se ha utilizado la técnica de Espectroscopía gamma de Absorción Total (TAGS, por sus siglas en inglés), basada en el uso de grand…
Observation of the rare B(s)(0) + decay from the combined analysis of CMS and LHCb data.
2015
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported licence.-- et al.
Measurement of the top quark pair production cross-section with ATLAS in the single lepton channel
2012
A measurement of the production cross-section for top quark pairs (t[bar over t]) in pp collisions at √s = 7 TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in the single lepton topology by requiring an electron or muon, large missing transverse momentum and at least three jets. With a data sample of 35 pb[superscript −1], two different multivariate methods, one of which uses b-quark jet identification while the other does not, use kinematic variables to obtain cross-section measurements of σ[subscript t bar over t] = 187 ± 11 (stat.) [+18 over −17] (syst.) ± 6 (lumi.) pb and σ[subscript t bar over t] = 173 ± 17 (stat.) [+18 ove…
Precision Measurement of the Mass and Lifetime of the Xi(-)(b) Baryon
2016
We report on measurements of the mass and lifetime of the Ξ[- over b] baryon using about 1800 Ξ[- over b] decays reconstructed in a proton-proton collision data set corresponding to an integrated luminosity of 3.0 fb[superscript -1] collected by the LHCb experiment. The decays are reconstructed in the Ξ[- over b] → Ξ[0 over c]π[superscript -], Ξ[0 over c] → pK[superscript -]K[superscript -]π[superscript +] channel and the mass and lifetime are measured using the Λ[0 over b] → Λ[+ over c]π[superscript -] mode as a reference. We measure M(Ξ[- over b] - M(Λ[0 over b]) = 178.36 ± 0.46 ± 0.16 MeV/c[superscript 2], (τ[subscript Ξ[- over b]/τ[subscript Λ[0 over b]) = 1.089 ± 0.026 ± 0.011, where…
Search for pair production of first or second generation leptoquarks in proton-proton collisions at sqrt(s)=7 TeV using the ATLAS detector at the LHC
2011
This paper describes searches for the pair production of first or second generation scalar leptoquarks using 35 pb−1 of proton-proton collision data recorded by the ATLAS detector at √s=7 TeV. Leptoquarks are searched in events with two oppositely-charged muons or electrons and at least two jets, and in events with one muon or electron, missing transverse momentum and at least two jets. After event selection, the observed yields are consistent with the predicted backgrounds. Leptoquark production is excluded at the 95% CL for masses MLQ<376 (319) GeV and MLQ<422 (362) GeV for first and second generation scalar leptoquarks, respectively, when assuming the branching fraction of a leptoquark…
Between idealism and realism: the global governance of nuclear non-proliferation and disarmament
2014
Why has it not yet been possible to bring the nuclear weapons regime to an end and why are prospects about a nuclear weapon free future so bleak? In this thesis, I analyze both the achievements and failures concerning the global governance of nuclear non-proliferation and disarmament. In the first chapter, I outline key terms and concepts as well as the historical backgrounds, which are essential for understanding the proliferation of nuclear weapons and the global governance of nuclear non-proliferation and disarmament. In the second chapter, I examine the efforts on nuclear non-proliferation and disarmament of four global key actors within the United Nations family: the General Assembly, …