49 research outputs found
Consistency of Lambda-Lambda hypernuclear events
Highlights of Lambda-Lambda emulsion events are briefly reviewed. Given three
accepted events, shell-model predictions based on p-shell Lambda hypernuclear
spectroscopic studies are shown to reproduce the Lambda-Lambda (LL) binding
energies of LL10Be and LL13B in terms of the LL binding energy of LL6He.
Predictions for other species offer judgement on several alternative
assignments of the LL13B KEK-E176 event, and on the assignments LL11Be and
LL12Be suggested recently for the KEK-E373 HIDA event. The predictions of the
shell model, spanning a wide range of A values, are compared with those of
cluster models, where the latter are available.Comment: Based on talk given by Avraham Gal at EXA 2011, Vienna, September
2011; Proceedings version prepared for the journal Hyperfine Interactions;
v2--slight changes, matches published versio
Glimpsing Colour in a World of Black and White
The past 40 years have taught us that nucleons are built of constituents that
carry colour charges with interactions governed by Quantum Chromodynamics
(QCD). How experiments (past, present and future) at Jefferson Lab probe
colourless nuclei to map out these internal colour degrees of freedom is
presented. When combined with theoretical calculations, these will paint a
picture of how the confinement of quarks and gluons, and the structure of the
QCD vacuum, determine the properties of all (light) strongly interacting
states.Comment: 8 pages, 9 figures. Invited talk at the Rutherford Centennial
Conference on Nuclear Physics, University of Manchester, 8-12 August 2011. To
appear in the Proceeding
Optimal use of Information for Measuring in Lepton+jets Events
We present a novel approach that is being developed at DZero for extracting
information from data through a direct comparison of all measured variables in
an event with a matrix element that describes the entire production process.
The method is exemplified in the extraction of the mass of the top quark in
top-antitop events in the lepton+jets final state. Monte Carlo studies suggest
that an improvement of about a factor of two in statistical uncertainty on the
mass of the top quark can be achieved relative to previously published work for
the same channel. Preliminary results from the re-analysis provide a reduction
in the statistical uncertainty of almost a factor of 1.6, corresponding to an
effective factor of 2.4 increase in the size of the data sample.Comment: presented at HCP200
--Dependence of Bond Energies in Double--- Hypernuclei
The -dependence of the bond energy of the
hypernuclear ground states is calculated in a three-body
model and in the Skyrme-Hartree-Fock approach.
Various and -nucleus or potentials
are used and the sensitivity of to the interactions
is discussed. It is shown that in medium and heavy
hypernuclei, is a linear function of
, where is rms radius of the hyperon orbital. It
looks unlikely that it will be possible to extract
interaction from the double- hypernuclear energies only, the
additional information about the -core interaction, in particular, on
is needed.Comment: 11 pages, LaTex, 3 figure
General analysis of signals with two leptons and missing energy at the Large Hadron Collider
A signal of two leptons and missing energy is challenging to analyze at the
Large Hadron Collider (LHC) since it offers only few kinematical handles. This
signature generally arises from pair production of heavy charged particles
which each decay into a lepton and a weakly interacting stable particle. Here
this class of processes is analyzed with minimal model assumptions by
considering all possible combinations of spin 0, 1/2 or 1, and of weak
iso-singlets, -doublets or -triplets for the new particles. Adding to existing
work on mass and spin measurements, two new variables for spin determination
and an asymmetry for the determination of the couplings of the new particles
are introduced. It is shown that these observables allow one to independently
determine the spin and the couplings of the new particles, except for a few
cases that turn out to be indistinguishable at the LHC. These findings are
corroborated by results of an alternative analysis strategy based on an
automated likelihood test.Comment: 18 pages, 3 figures, LaTe
Study of B0(s)→K0Sh+h′− decays with first observation of B0s→K0SK±π∓ and B0s→K0Sπ+π−
A search for charmless three-body decays of B 0 and B0s mesons with a K0S meson in the final state is performed using the pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, collected at a centre-of-mass energy of 7 TeV recorded by the LHCb experiment. Branching fractions of the B0(s)→K0Sh+h′− decay modes (h (′) = π, K), relative to the well measured B0→K0Sπ+π− decay, are obtained. First observation of the decay modes B0s→K0SK±π∓ and B0s→K0Sπ+π− and confirmation of the decay B0→K0SK±π∓ are reported. The following relative branching fraction measurements or limits are obtained B(B0→K0SK±π∓)B(B0→K0Sπ+π−)=0.128±0.017(stat.)±0.009(syst.), B(B0→K0SK+K−)B(B0→K0Sπ+π−)=0.385±0.031(stat.)±0.023(syst.), B(B0s→K0Sπ+π−)B(B0→K0Sπ+π−)=0.29±0.06(stat.)±0.03(syst.)±0.02(fs/fd), B(B0s→K0SK±π∓)B(B0→K0Sπ+π−)=1.48±0.12(stat.)±0.08(syst.)±0.12(fs/fd)B(B0s→K0SK+K−)B(B0→K0Sπ+π−)∈[0.004;0.068]at90%CL
QCD and strongly coupled gauge theories : challenges and perspectives
We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.Peer reviewe