772 research outputs found
Electric quadrupole and magnetic dipole moments of odd nuclei near the magic ones in a self-consistent approach
We present a model which describes the properties of odd-even nuclei with one
nucleon more, or less, with respect to the magic number. In addition to the
effects related to the unpaired nucleon, we consider those produced by the
excitation of the closed shell core. By using a single particle basis generated
with Hartree-Fock calculations, we describe the polarization of the doubly
magic-core with Random Phase Approximation collective wave functions. In every
step of the calculation, and for all the nuclei considered, we use the same
finite-range nucleon-nucleon interaction. We apply our model to the evaluation
of electric quadrupole and magnetic dipole moments of odd-even nuclei around
oxygen, calcium, zirconium, tin and lead isotopes. Our Random Phase
Approximation description of the polarization of the core improves the
agreement with experimental data with respect to the predictions of the
independent particle model. We compare our results with those obtained in
first-order perturbation theory, with those produced by
Hartree-Fock-Bogolioubov calculations and with those generated within the
Landau-Migdal theory of finite Fermi systems. The results of our universal,
self-consistent, and parameter free approach have the same quality of those
obtained with phenomenological approaches where the various terms of the
nucleon-nucleon interaction are adapted to reproduce some specific experimental
data. A critical discussion on the validity of the model is presented.Comment: 18 pages, 7 figures, 7 table
Relativistic Green's function approach to parity-violating quasielastic electron scattering
A relativistic Green's function approach to parity-violating quasielastic
electron scattering is presented. The components of the hadron tensor are
expressed in terms of the single particle Green's function, which is expanded
in terms of the eigenfunctions of the non-Hermitian optical potential, in order
to account for final state interactions without any loss of flux. Results for
C, O, and Ca are presented and discussed. The effect of
the strange quark contribution to the nuclear current is investigated.Comment: 24 pages, 13 figure
Neutrino-nucleus quasi-elastic scattering and strange quark effects
A relativistic distorted-wave impulse-approximation model is applied to
quasi-elastic neutrino-nucleus scattering. The bound state is obtained in the
framework of the relativistic mean field theory and the final state interaction
is taken into account in the scattering state. Results for the charged- and
neutral-current neutrino (antineutrino) reactions on C target nucleus
are presented and the sensitivity of various quantities to the strange quark
content of the nucleon weak current is discussed.Comment: 18 pages, 10 figure
Evidence for an excess of B -> D(*) Tau Nu decays
Based on the full BaBar data sample, we report improved measurements of the
ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B -> D(*) l Nu), where l is either e or
mu. These ratios are sensitive to new physics contributions in the form of a
charged Higgs boson. We measure R(D) = 0.440 +- 0.058 +- 0.042 and R(D*) =
0.332 +- 0.024 +- 0.018, which exceed the Standard Model expectations by 2.0
sigma and 2.7 sigma, respectively. Taken together, our results disagree with
these expectations at the 3.4 sigma level. This excess cannot be explained by a
charged Higgs boson in the type II two-Higgs-doublet model. We also report the
observation of the decay B -> D Tau Nu, with a significance of 6.8 sigma.Comment: Expanded section on systematics, text corrections, improved the
format of Figure 2 and included the effect of the change of the Tau
polarization due to the charged Higg
Search for the decay modes D^0 â e^+e^-, D^0 â ÎŒ^+ÎŒ^-, and D^0 â e^±Όâ
We present searches for the rare decay modes D^0âe^+e^-, D^0âÎŒ^+ÎŒ^-, and D^0âe^±Ό^â in continuum e^+e^-âcc events recorded by the BABAR detector in a data sample that corresponds to an integrated luminosity of 468ââfb^(-1). These decays are highly GlashowâIliopoulosâMaiani suppressed but may be enhanced in several extensions of the standard model. Our observed event yields are consistent with the expected backgrounds. An excess is seen in the D^0âÎŒ^+ÎŒ^- channel, although the observed yield is consistent with an upward background fluctuation at the 5% level. Using the FeldmanâCousins method, we set the following 90% confidence level intervals on the branching fractions: B(D^0âe^+e^-)<1.7Ă10^(-7), B(D^0âÎŒ^+ÎŒ^-) within [0.6,8.1]Ă10^(-7), and B(D^0âe^±Ό^â)<3.3Ă10^(-7)
Observation and study of baryonic B decays: B -> D(*) p pbar, D(*) p pbar pi, and D(*) p pbar pi pi
We present a study of ten B-meson decays to a D(*), a proton-antiproton pair,
and a system of up to two pions using BaBar's data set of 455x10^6 BBbar pairs.
Four of the modes (B0bar -> D0 p anti-p, B0bar -> D*0 p anti-p, B0bar -> D+ p
anti-p pi-, B0bar -> D*+ p anti-p pi-) are studied with improved statistics
compared to previous measurements; six of the modes (B- -> D0 p anti-p pi-, B-
-> D*0 p anti-p pi-, B0bar -> D0 p anti-p pi- pi+, B0bar -> D*0 p anti-p pi-
pi+, B- -> D+ p anti-p pi- pi-, B- -> D*+ p anti-p pi- pi-) are first
observations. The branching fractions for 3- and 5-body decays are suppressed
compared to 4-body decays. Kinematic distributions for 3-body decays show
non-overlapping threshold enhancements in m(p anti-p) and m(D(*)0 p) in the
Dalitz plots. For 4-body decays, m(p pi-) mass projections show a narrow peak
with mass and full width of (1497.4 +- 3.0 +- 0.9) MeV/c2, and (47 +- 12 +- 4)
MeV/c2, respectively, where the first (second) errors are statistical
(systematic). For 5-body decays, mass projections are similar to phase space
expectations. All results are preliminary.Comment: 28 pages, 90 postscript figures, submitted to LP0
Measurement of the cross-section of high transverse momentum vector bosons reconstructed as single jets and studies of jet substructure in pp collisions at âs = 7 TeV with the ATLAS detector
This paper presents a measurement of the cross-section for high transverse momentum W and Z bosons produced in pp collisions and decaying to all-hadronic final states. The data used in the analysis were recorded by the ATLAS detector at the CERN Large Hadron Collider at a centre-of-mass energy of âs = 7 TeV;{\rm Te}{\rm V}4.6\;{\rm f}{{{\rm b}}^{-1}}{{p}_{{\rm T}}}\gt 320\;{\rm Ge}{\rm V}|\eta |\lt 1.9{{\sigma }_{W+Z}}=8.5\pm 1.7$ pb and is compared to next-to-leading-order calculations. The selected events are further used to study jet grooming techniques
Search for pair-produced long-lived neutral particles decaying to jets in the ATLAS hadronic calorimeter in ppcollisions at âs=8TeV
The ATLAS detector at the Large Hadron Collider at CERN is used to search for the decay of a scalar boson to a pair of long-lived particles, neutral under the Standard Model gauge group, in 20.3fbâ1of data collected in protonâproton collisions at âs=8TeV. This search is sensitive to long-lived particles that decay to Standard Model particles producing jets at the outer edge of the ATLAS electromagnetic calorimeter or inside the hadronic calorimeter. No significant excess of events is observed. Limits are reported on the product of the scalar boson production cross section times branching ratio into long-lived neutral particles as a function of the proper lifetime of the particles. Limits are reported for boson masses from 100 GeVto 900 GeV, and a long-lived neutral particle mass from 10 GeVto 150 GeV
Air conditioning and electricity expenditure: The role of climate in temperate countries
This paper investigates how households adopt and use air conditioning to adapt to climate change and increasingly high temperatures, which pose a threat to the health of vulnerable populations. The analysis examines conditions in eight temperate, industrialized countries (Australia, Canada, France, Japan, the Netherlands, Spain, Sweden, and Switzerland). The identification strategy exploits cross-country and cross-household variations by matching geocoded households with climate data. Our findings suggest that households respond to excess heat by purchasing and using air conditioners, leading to increased electricity consumption. Households on average spend 35%â42% more on electricity when they adopt air conditioning. Through an illustrative analysis, we show that climate change and the growing demand for air conditioning are likely to exacerbate energy poverty. The number of energy poor who spend a high share of income on electricity increases, and households in the lowest income quantile are the most negatively affected
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