445 research outputs found
Low-Mass WIMP Sensitivity and Statistical Discrimination of Electron and Nuclear Recoils by Varying Luke-Neganov Phonon Gain in Semiconductor Detectors
Amplifying the phonon signal in a semiconductor dark matter detector can be
accomplished by operating at high voltage bias and converting the electrostatic
potential energy into Luke-Neganov phonons. This amplification method has been
validated at up to |E|=40V/cm without producing leakage in CDMSII Ge detectors,
allowing sensitivity to a benchmark WIMP with mass = 8GeV and cross section
1.8e-42cm^2 assuming flat electronic recoil backgrounds near threshold.
Furthermore, for the first time we show that differences in Luke-Neganov gain
for nuclear and electronic recoils can be used to discriminate statistically
between low-energy background and a hypothetical WIMP signal by operating at
two distinct voltage biases. Specifically, 99% of events have p-value<1e-8 for
a simulated 20kg-day experiment with a benchmark WIMP signal with mass =8GeV
and cross section =3.3e-41cm^2.Comment: 6 pages, 5 figures To be published in Journal of Low Temperature
Physic
b-physics signals of the lightest CP-odd Higgs in the NMSSM at large tan beta
We investigate the low energy phenomenology of the lighter pseudoscalar
in the NMSSM. The mass can naturally be small due to a global
symmetry of the Higgs potential, which is only broken by trilinear
soft terms. The mass is further protected from renormalization group
effects in the large limit. We calculate the
amplitude at leading order in and work out the contributions to
rare , and radiative -decays and mixing. We obtain
constraints on the mass and couplings and show that masses down to
MeV are allowed. The -physics phenomenology of the NMSSM
differs from the MSSM in the appearance of sizeable renormalization effects
from neutral Higgses to the photon and gluon dipole operators and the breakdown
of the MSSM correlation between the branching ratio and
mixing. For masses above the tau threshold the
can be searched for in processes with branching ratios
\lsim 10^{-3}.Comment: 18 pages, 3 figures; references adde
Constraining the breaking scale in naturally R-parity conserving supersymmetric models
We obtain a relation between right-handed gauge boson mass and soft squark
mass in naturally R-parity conserving general supersymmetric left-right models.
This relation implies that either is lighter than twice the soft squark
mass, or a ratio of vacuum expectation values (VEVs) in the model, denoted by
, is close to its value of unity in the limit of vanishing D-terms.
Generally, we find that for heavy is larger than one, and
that the right-handed sneutrino VEV, responsible for spontaneous R-parity
breaking, is at most of the order , where is
supersymmetry breaking scale and is the Yukawa coupling in
Majorana mass term for right-handed neutrinos. These constraints follow from
and gauge invariance of the ground state of the theory.Comment: 10 pages, LaTeX, no figures. Version to appear in Phys.Lett.
Higgs Scalars in the Minimal Non-minimal Supersymmetric Standard Model
We consider the simplest and most economic version among the proposed
non-minimal supersymmetric models, in which the -parameter is promoted to
a singlet superfield, whose all self-couplings are absent from the
renormalizable superpotential. Such a particularly simple form of the
renormalizable superpotential may be enforced by discrete -symmetries which
are extended to the gravity-induced non-renormalizable operators as well. We
show explicitly that within the supergravity-mediated supersymmetry-breaking
scenario, the potentially dangerous divergent tadpoles associated with the
presence of the gauge singlet first appear at loop levels higher than 5 and
therefore do not destabilize the gauge hierarchy. The model provides a natural
explanation for the origin of the -term, without suffering from the
visible axion or the cosmological domain-wall problem. Focusing on the Higgs
sector of this minimal non-minimal supersymmetric standard model, we calculate
its effective Higgs potential by integrating out the dominant quantum effects
due to stop squarks. We then discuss the phenomenological implications of the
Higgs scalars predicted by the theory for the present and future high-energy
colliders. In particular, we find that our new minimal non-minimal
supersymmetric model can naturally accommodate a relatively light charged Higgs
boson, with a mass close to the present experimental lower bound.Comment: 63 pages (12 figures), extended versio
Particle Spectrum in the Non-Minimal Supersymmetric Standard Model with
We present a detailed discussion of the particle spectrum of the Non-Minimal
Supersymmetric Standard Model (NMSSM), containing two Higgs doublets and a
singlet, in the limit . This is compared with the
corresponding particle spectrum of the Minimal Supersymmetric Standard Model
(MSSM). In this limit the singlet vacuum expectation value is forced to be
large, of the order of TeV, and the singlet decouples from the lightest
scalar Higgs boson and the neutralinos. With the exception of the lightest
Higgs boson, the particle spectrum in the model turns out to be heavy. The
radiatively corrected lightest Higgs boson mass is in the neighbourhood of
GeV.Comment: 20 pages plain LaTeX and 3 figures supplied on request from
[email protected] or [email protected]
Production and Decay of Neutralinos in the Next-To-Minimal Supersymmetric Standard Model
Within the framework of the Next-To-Minimal Supersymmetric Standard Model
(NMSSM) we study neutralino production () at center-of-mass energies between 100
and 600 GeV and the decays of the heavier neutralinos into the LSP plus a
fermion pair, a photon or a Higgs boson. For representative gaugino/higgsino
mixing scenarios, where the light neutralinos have significant singlet
components, we find some striking differences between the NMSSM and the minimal
supersymmetric model. Since in the NMSSM neutralino and Higgs sector are
strongly correlated, the decay of the second lightest neutralino into a Higgs
boson and the LSP often is kinematically possible and even dominant in a large
parameter region of typical NMSSM scenarios. Also, the decay rates into final
states with a photon may be enhanced.Comment: 36 pages, latex, 10 uuendcoded figures, complete ps file available at
ftp://ftp.physik.uni-wuerzburg.de/pub/preprint/WUE-ITP-95-021.ps.g
Whole-exome sequencing and targeted copy number analysis in primary ciliary dyskinesia
Primary ciliary dyskinesia (PCD) is an autosomal-recessive disorder resulting from loss of normal ciliary function. Symptoms include neonatal respiratory distress, chronic sinusitis, bronchiectasis, situs inversus, and infertility. Clinical features may be subtle and highly variable, making the diagnosis of PCD challenging. The diagnosis can be confirmed with ciliary ultrastructure analysis and/or molecular genetic testing of 32 PCD-associated genes. However, because of this genetic heterogeneity, comprehensive molecular genetic testing is not considered the standard of care, and the most efficient molecular approach has yet to be elucidated. Here, we propose a cost-effective and time-efficient molecular genetic algorithm to solve cases of PCD. We conducted targeted copy number variation (CNV) analysis and/or whole-exome sequencing on 20 families (22 patients) from a subset of 45 families (52 patients) with a clinical diagnosis of PCD who did not have a molecular genetic diagnosis after Sanger sequencing of 12 PCD-associated genes. This combined molecular genetic approach led to the identification of 4 of 20 (20%) families with clinically significant CNVs and 7 of 20 (35%) families with biallelic pathogenic mutations in recently identified PCD genes, resulting in an increased molecular genetic diagnostic rate of 55% (11/20). In patients with a clinical diagnosis of PCD, whole-exome sequencing followed by targeted CNV analysis results in an overall molecular genetic yield of 76% (34/45)
Search for single top quarks in the tau+jets channel using 4.8 fb of collision data
We present the first direct search for single top quark production using tau
leptons. The search is based on 4.8 fb of integrated luminosity
collected in collisions at =1.96 TeV with the D0 detector
at the Fermilab Tevatron Collider. We select events with a final state
including an isolated tau lepton, missing transverse energy, two or three jets,
one or two of them tagged. We use a multivariate technique to discriminate
signal from background. The number of events observed in data in this final
state is consistent with the signal plus background expectation. We set in the
tau+jets channel an upper limit on the single top quark cross section of
\TauLimObs pb at the 95% C.L. This measurement allows a gain of 4% in expected
sensitivity for the observation of single top production when combining it with
electron+jets and muon+jets channels already published by the D0 collaboration
with 2.3 fb of data. We measure a combined cross section of
\SuperCombineXSall pb, which is the most precise measurement to date.Comment: 12 pages, 5 figure
Measurement of Z/gamma*+jet+X angular distributions in ppbar collisions at sqrt{s}=1.96 TeV
We present the first measurements at a hadron collider of differential cross
sections for Z+jet+X production in delta phi(Z, jet), |delta y(Z, jet)| and
|y_boost(Z, jet)|. Vector boson production in association with jets is an
excellent probe of QCD and constitutes the main background to many small cross
section processes, such as associated Higgs production. These measurements are
crucial tests of the predictions of perturbative QCD and current event
generators, which have varied success in describing the data. Using these
measurements as inputs in tuning event generators will increase the
experimental sensitivity to rare signals.Comment: Published in Physics Letters B 682 (2010), pp. 370-380. 15 pages, 6
figure
Search for the standard model Higgs boson in tau final states
We present a search for the standard model Higgs boson using hadronically
decaying tau leptons, in 1 inverse femtobarn of data collected with the D0
detector at the Fermilab Tevatron ppbar collider. We select two final states:
tau plus missing transverse energy and b jets, and tau+ tau- plus jets. These
final states are sensitive to a combination of associated W/Z boson plus Higgs
boson, vector boson fusion and gluon-gluon fusion production processes. The
observed ratio of the combined limit on the Higgs production cross section at
the 95% C.L. to the standard model expectation is 29 for a Higgs boson mass of
115 GeV.Comment: publication versio
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