The anomalous magnetic moment (g-2) of the muon was measured with a precision
of 0.54 ppm in Experiment 821 at Brookhaven National Laboratory. A difference
of 3.2 standard deviations between this experimental value and the prediction
of the Standard Model has persisted since 2004; in spite of considerable
experimental and theoretical effort, there is no consistent explanation for
this difference. This comparison hints at physics beyond the Standard Model,
but it also imposes strong constraints on those possibilities, which include
supersymmetry and extra dimensions. The collaboration is preparing to relocate
the experiment to Fermilab to continue towards a proposed precision of 0.14
ppm. This will require 20 times more recorded decays than in the previous
measurement, with corresponding improvements in the systematic uncertainties.
We describe the theoretical developments and the experimental upgrades that
provide a compelling motivation for the new measurement.
The radioactive contamination of ZnWO4 crystal scintillators has been
measured deep underground at the Gran Sasso National Laboratory (LNGS) of the
INFN in Italy with a total exposure 3197 kg x h. Monte Carlo simulation,
time-amplitude and pulse-shape analyses of the data have been applied to
estimate the radioactive contamination of the ZnWO4 samples. One of the ZnWO4
crystals has also been tested by ultra-low background gamma spectrometry. The
radioactive contaminations of the ZnWO4 samples do not exceed 0.002 – 0.8
mBq/kg (depending on the radionuclide), the total alpha activity is in the
range: 0.2 - 2 mBq/kg. Particular radioactivity, beta active 65Zn and alpha
active 180W, has been detected. The effect of the re-crystallization on the
radiopurity of the ZnWO4 crystal has been studied. The radioactive
contamination of samples of the ceramic details of the set-ups used in the
crystals growth has been checked by low background gamma spectrometry. A
project scheme on further improvement of the radiopurity level of the ZnWO4
crystal scintillators is briefly addressed.
We present an analysis of the Lambda(1405) resonance in p+p reactions at a
kinetic beam energy of 3.5 GeV, measured by the High Acceptance Di-Electron
Spectrometer (HADES). The resonance is reconstructed in the two charged decay
channels Sigma^(+/-) pi^(-/+), with help of a kinematic refit, which improves
the mass resolution. The high misidentification of pions and protons as kaons
required the development of a sophisticated sideband analysis, which can
describe the misidentification background quite well.
We examine electron-capture supernovae (ECSNe) as sources of elements heavier
than iron in the solar system and in Galactic halo stars. Nucleosynthesis
calculations are performed on the basis of thermodynamic histories of mass
elements from a fully self-consistent, two-dimensional (2D) hydrodynamic
explosion model of an ECSN. We find that neutron-rich convective lumps with an
electron fraction down to Ye,min=0.40, which are absent in the one-dimensional
(1D) counterpart, allow for interesting production of elements between the iron
group and N=50 nuclei (from Zn to Zr, with little Ga) in nuclear statistical
equilibrium and by the alpha-process. Our models yield very good agreement with
the Ge, Sr, Y, and Zr abundances of r-process deficient Galactic halo stars and
constrain the occurrence of ECSNe to ~4% of all stellar core-collapse events.
If tiny amounts of additional material with slightly lower Ye,min down to
~0.30-0.35 were also ejected - which presently cannot be excluded because of
the limitations of resolution and two-dimensionality of the model -, a weak
r-process can yield elements beyond N=50 up to Pd, Ag, and Cd as observed in
the r-process deficient stars.
The Super Proton Synchrotron (SPS) at CERN covers one of the most interesting
regions of the phase diagram (T - \mu_{B}) of strongly interacting matter. The
study of central Pb+Pb collisions by NA49 indicate that the threshold for
deconfinement is reached already at the low SPS energies. Theoretical
considerations predict a critical point of strongly interacting matter at
energies accessible at the SPS. The NA61/SHINE experiment, a successor of the
NA49 project, will study hadron production in p+p, p+A, h+A, and A+A reactions
at various energies. The broad physics program includes the investigation of
the properties of strongly interacting matter, as well as precision
measurements of hadron spectra for the T2K neutrino experiment and for the
Pierre Auger Observatory and KASCADE cosmic-ray projects. The main physics
goals of the NA61/SHINE ion program are to study the properties of the onset of
deconfinement at low SPS energies and to find signatures of the critical point
of strongly interacting matter. To achieve these goals a broad range in the (T
- \mu_{B}) phase diagram will be covered by performing an energy (10A-158A
GeV/c) and system size (p+p, B+C, Ar+Ca, Xe+La) scan. The first data for this
2-D scan were taken in 2009, i.e. p+p interactions at 20, 30, 40, 80, 158 GeV/c
beam energy. This contribution will summarize physics arguments for the
NA61/SHINE ion program, show the detector performance and present the current
status of the experiment and plans for the next years.
Title:
Quartet of spin-3/2 baryons in chiral multiplet $(1, 1/2) \oplus (1/2,
1) $ with mirror assignment
Authors:
Keitaro Nagata
We study the possible existence of chiral partners in the spin-$\thalf$
sector of the baryon spectrum. We consider a quartet scheme where four spin-3/2
baryons, $P_{33}$, $D_{33}$, $D_{13}$ and $P_{13}$, group into
higher-dimensional chiral multiplets $(1, \half)\oplus (\half,1)$ with a mirror
assignment. With an effective $SU(2)_R\times SU(2)_L$ Lagrangian, we derive
constraints imposed by chiral symmetry together with the mirror assignment on
the masses and coupling constants of the quartet. Using those constraints, we
try to find a set of baryons suitable for the chiral quartet. It turns out that
three cases reasonably agree with the features of the quartet: (1)
($\Delta(1232)$, $\Delta(1700)$, N(1520), $N(1720))$, (2) ($\Delta(1232)$,
$\Delta(1940)$, N(1520), $N(1720))$, (3) ($\Delta(1600)$, $\Delta(1940)$,
N(1520$, $N(1720))$. We discuss the features of these cases with careful
attention to how they are distinguished. We also study four spin-$\thalf$
baryons that are approximately degenerate, ($\Delta(1920)$, $\Delta(1940)$,
N(1900), N(2080)), using the quartet scheme.
Title:
Associated strangeness production in the pp to pK^+K^-p and pp to pK^+
pi^0 Sigma^0 reactions
Authors:
Ju-Jun Xie,
Colin Wilkin
The total and differential cross sections for associated strangeness
production in the $pp \to pK^+K^-p$ and $pp \to pK^+\pi^0\Sigma^0$ reactions
have been studied in a unified approach using an effective Lagrangian model. It
is assumed that both the $K^-p$ and $\pi^0\Sigma^0$ final states originate from
the decay of the $\Lambda(1405)$ resonance which was formed in the production
chain $pp\to p(N^*(1535)\to K^+\Lambda(1405))$. The available experimental data
are well reproduced, especially the ratio of the two total cross sections,
which is much less sensitive to the particular model of the entrance channel.
The significant coupling of the $N^*(1535)$ resonance to $\Lambda(1405) K$ is
further evidence for large $s \bar{s}$ components in the quark wave function of
the $N^*(1535)$ resonance.
1002.3824wilson : In this paper Sedrakyan and Chubukov have finally resolved the long-standing issue about the origin of the pseudogap in cuprates. This study...
1005.5173renner : To clarify in response to the above comment, our main result is that quantum theory cannot be *extended*. We consider an extension to a the...
1005.5173peaches : I'm not sure that it's fair to say that this is is an extension of Bell's result in the general case because the main theorem relies on the ...
1005.4932ayvlasov : I am not quite realizing, if it is necessary to make some comments, because most arguments already have been raised by few different people ...