1,263 research outputs found
Light dark matter in the NMSSM: upper bounds on direct detection cross sections
In the Next-to-Minimal Supersymmetric Standard Model, a bino-like LSP can be
as light as a few GeV and satisfy WMAP constraints on the dark matter relic
density in the presence of a light CP-odd Higgs scalar. We study upper bounds
on the direct detection cross sections for such a light LSP in the mass range
2-20 GeV in the NMSSM, respecting all constraints from B-physics and LEP. The
OPAL constraints on e^+ e^- -> \chi^0_1 \chi^0_i (i > 1) play an important role
and are discussed in some detail. The resulting upper bounds on the
spin-independent and spin-dependent nucleon cross sections are ~ 10^{-42}
cm^{-2} and ~ 4\times 10^{-40} cm^{-2}, respectively. Hence the upper bound on
the spin-independent cross section is below the DAMA and CoGeNT regions, but
could be compatible with the two events observed by CDMS-II.Comment: 17 pages, 3 figure
A single hollow beam optical trap for cold atoms
We present an optical trap for atoms that we have developed for precision
spectroscopy measurements. Cold atoms are captured in a dark region of space
inside a blue-detuned hollow laser beam formed by an axicon. We analyze the
light potential in a ray optics picture and experimentally demonstrate trapping
of laser-cooled metastable xenon atoms.Comment: 12 pages, 8 figure
One size doesn’t fit all: the influence of supervisors’ power tactics and subordinates’ need for cognitive closure on burnout and stress
The present research investigated the notion of fit between supervisors’ power tactics and subordinates’ need for cognitive closure (NFCC) on subordinates’ burnout and stress. Subordinates who tend to avoid ambiguity (high NFCC) were expected to experience relatively less burnout (Study 1) and stress (Study 2) if their supervisors utilize harsh (controlling and unequivocal) power tactics and more burnout and stress if their supervisors utilize soft (autonomy-supportive and equivocal) power tactics. In contrast, it was expected that subordinates who avoid firm and binding conclusions (low NFCC) would experience relatively less burnout and stress if their supervisors use soft power tactics and more burnout and stress if they use harsh power tactics. Two studies conducted in diverse organizational settings supported these hypotheses. Collectively, these results support the conclusion that soft (vs. harsh) power tactics are not always associated with better (vs. worse) organizational outcomes. Theoretical and practical implications for organizations are discussed
Supersymmetric mass spectra and the seesaw type-I scale
We calculate supersymmetric mass spectra with cMSSM boundary conditions and a
type-I seesaw mechanism added to explain current neutrino data. Using
published, estimated errors on SUSY mass observables for a combined LHC+ILC
analysis, we perform a theoretical analysis to identify parameter
regions where pure cMSSM and cMSSM plus seesaw type-I might be distinguishable
with LHC+ILC data. The most important observables are determined to be the
(left) smuon and selectron masses and the splitting between them, respectively.
Splitting in the (left) smuon and selectrons is tiny in most of cMSSM parameter
space, but can be quite sizeable for large values of the seesaw scale,
. Thus, for very roughly GeV hints for type-I
seesaw might appear in SUSY mass measurements. Since our numerical results
depend sensitively on forecasted error bars, we discuss in some detail the
accuracies, which need to be achieved, before a realistic analysis searching
for signs of type-I seesaw in SUSY spectra can be carried out.Comment: 17 pages, 7 figure
Development of the Bélanger Equation and Backwater Equation by Jean-Baptiste Bélanger (1828)
A hydraulic jump is the sudden transition from a high-velocity to a low-velocity open channel flow. The application of the momentum principle to the hydraulic jump is commonly called the Bélanger equation, but few know that Bélanger's (1828) treatise was focused on the study of gradually varied open channel flows. Further, although Bélanger understood the rapidly-varied nature of the jump flow, he applied incorrectly the Bernoulli principle in 1828, and corrected his approach 10 years later. In 1828, his true originality lay in the successful development of the backwater equation for steady, one-dimensional gradually-varied flows in an open channel, together with the introduction of the step method, distance calculated from depth, and the concept of critical flow conditions
B-Meson Gateways to Missing Charmonium Levels
We outline a coherent strategy for exploring the four remaining narrow
charmonium states [\eta_{c}^{\prime}(2\slj{1}{1}{0}),
h_{c}(1\slj{1}{2}{1}), \eta_{c2}(1\slj{1}{3}{2}), and
\psi_{2}(1\slj{3}{3}{2})] expected to lie below charm threshold. Produced in
-meson decays, these levels should be identifiable \textit{now} via striking
radiative transitions among charmonium levels and in exclusive final states of
kaons and pions. Their production and decay rates will provide much needed new
tests for theoretical descriptions of heavy quarkonia.Comment: 5 pages, uses ReVTeX and BibTe
Quartic Anomalous Couplings in Colliders
We study the constraints on the vertices ,
, and that can be obtained from
triple-gauge-boson production at the next generation of linear
colliders operating in the mode. We analyze the processes
(, or ) and show that these reactions
increase the potential of machines to search for anomalous
four-gauge-boson interactions.Comment: 15 pages, Latex file using ReVteX, 4 uufiled figures include
Asymmetric total synthesis of (+)-virosine a via sequential nucleophilic cyclizations onto an activated formamide
Abstract: The first synthesis of tetracyclic alkaloid virosine A is reported. The natural alkaloid was prepared in only 13 steps, in an enantioenriched form. The azabicyclo[2.2.2]octane core was efficiently assembled using a key Vilsmeier–Haack and Mannich cyclizations sequence performed in one pot
Relic density of dark matter in the NMSSM
We present a code to compute the relic density of dark matter in the
Next-to-Minimal Supersymmetric Standard Model (NMSSM). Dominant corrections to
the Higgs masses are calculated with NMHDECAY as well as theoretical and
collider constraints. All neutralino annihilation and coannihilation processes
are then computed with an extended version of micrOMEGAs, taking into acount
higher order corrections to Higgs vertices. We explore the parameter space of
the NMSSM and consider in particular the case of a bino LSP, of a mixed
bino-higgsino LSP and of a singlino LSP. As compared to the MSSM, neutralino
annihilation is often more efficient as it can take place via (additional)
Higgs resonances as well as annihilation into light Higgs states. Models with a
large singlino component can be compatible with WMAP constraints.Comment: 25 pages, 8 figures; one reference added and minor change in
acknowledgement
Bosonic Quartic Couplings at LHC
We analyze the potential of the CERN Large Hadron Collider (LHC) to study
anomalous quartic vector-boson interactions Z Z gamma gamma, Z Z Z gamma, W+ W-
gamma gamma, and W+ W- Z gamma through the weak boson fusion processes q q -> q
q gamma gamma and q q -> q q gamma Z(-> l+ l-) with l = electron or muon. After
a careful study of the backgrounds and how to extract them from the data, we
show that the process p p -> j j gamma l+ l- is potentially the most sensitive
to deviations from the Standard Model, improving the sensitivity to anomalous
couplings by up to a factor 10^4 (10^2) with respect to the present direct
(indirect) limits.Comment: 18 pages, 2 figures, revised versio
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