20,548 research outputs found
Raising the Higgs mass with Yukawa couplings for isotriplets in vector-like extensions of minimal supersymmetry
Extra vector-like matter with both electroweak-singlet masses and large
Yukawa couplings can significantly raise the lightest Higgs boson mass in
supersymmetry through radiative corrections. I consider models of this type
that involve a large Yukawa coupling between weak isotriplet and isodoublet
chiral supermultiplets. The particle content can be completed to provide
perturbative gauge coupling unification, in several different ways. The impact
on precision electroweak observables is shown to be acceptably small, even if
the new particles are as light as the current experimental bounds of order 100
GeV. I study the corrections to the lightest Higgs boson mass, and discuss the
general features of the collider signatures for the new fermions in these
models.Comment: 30 page
Cluster Probes of Dark Energy Clustering
Cluster abundances are oddly insensitive to canonical early dark energy.
Early dark energy with sound speed equal to the speed of light cannot be
distinguished from a quintessence model with the equivalent expansion history
for but negligible early dark energy density, despite the different early
growth rate. However, cold early dark energy, with a sound speed much smaller
than the speed of light, can give a detectable signature. Combining cluster
abundances with cosmic microwave background power spectra can determine the
early dark energy fraction to 0.3 % and distinguish a true sound speed of 0.1
from 1 at 99 % confidence. We project constraints on early dark energy from the
Euclid cluster survey, as well as the Dark Energy Survey, using both current
and projected Planck CMB data, and assess the impact of cluster mass
systematics. We also quantify the importance of dark energy perturbations, and
the role of sound speed during a crossing of
Three-loop corrections to the lightest Higgs scalar boson mass in supersymmetry
I evaluate the largest three-loop corrections to the mass of the lightest
Higgs scalar boson in the Minimal Supersymmetric Standard Model in a
mass-independent renormalization scheme, using effective field theory and
renormalization group methods. The contributions found here are those that
depend only on strong and Yukawa interactions and on the leading and
next-to-leading logarithms of the ratio of a typical superpartner mass scale to
the top quark mass. The approximation assumes that all superpartners and the
other Higgs bosons can be treated as much heavier than the top quark, but does
not assume their degeneracy. I also discuss the consistent addition of the
three-loop corrections to a complete two-loop calculation.Comment: 9 page
The transition of ground-based space environmental effects testing to the space environment
The goal of the space flight program at the Center for Commercial Development of Space (CCDS)--Materials for Space Structures is to provide environmentally stable structural materials to support the continued humanization and commercialization of the space frontier. Information on environmental stability will be obtained through space exposure, evaluation, documentation, and subsequent return to the supplier of the candidate material for internal investigation. This program provides engineering and scientific service to space systems development firms and also exposes CCDS development candidate materials to space environments representative of in-flight conditions. The maintenance of a technological edge in space for NASA suggests the immediate search for space materials that maintain their structural integrity and remain environmentally stable. The materials being considered for long-lived space structures are complex, high strength/weight ratio composites. In order for these new candidate materials to qualify for use in space structures, they must undergo strenuous testing to determine their reliability and stability when subjected to the space environment. Ultraviolet radiation, atomic oxygen, debris/micrometeoroids, charged particles radiation, and thermal fatigue all influence the design of space structural materials. The investigation of these environmental interactions is the key purpose of this center. Some of the topics discussed with respect to the above information include: the Space Transportation System, mission planning, spaceborne experiments, and space flight payloads
The Arecibo Dual-Beam Survey: Arecibo and VLA Observations
The Arecibo Dual-Beam Survey is a "blind" 21 cm search for galaxies covering
\~430 deg^2 of sky. We present the data from the detection survey as well as
from the follow-up observations to confirm detections and improve positions and
flux measurements. We find 265 galaxies, many of which are extremely low
surface brightness. Some of these previously uncataloged galaxies lie within
the zone of avoidance where they are obscured by the gas and dust in our
Galaxy. 81 of these sources are not previously cataloged optically and there
are 11 galaxies that have no associated optical counterpart or are only
tentatively associated with faint wisps of nebulosity on the Digitized Sky
Survey images. We discuss the properties of the survey and in particular we
make direct determinations of the completeness and reliability of the sample.
The behavior of the completeness and its dependencies is essential for
determining the HI mass function. We leave the discussion of the mass function
for a later paper, but do note that we find many low surface brightness
galaxies and 7 sources with M_HI < 10^8 Msolar.Comment: 23 pages, 20 figures, accepted ApJS. For tables 2 and 3 only the
first page has been included. ASCII tables are provided separatel
MicroRNA-330-5p as a putative modulator of neoadjuvant chemoradiotherapy sensitivity in oesophageal adenocarcinoma
Oesophageal adenocarcinoma (OAC) is the sixth most common cause of cancer deaths worldwide, and the 5-year survival rate for patients diagnosed with the disease is approximately 17%. The standard of care for locally advanced disease is neoadjuvant chemotherapy or, more commonly, combined neoadjuvant chemoradiation therapy (neo-CRT) prior to surgery. Unfortunately, ~60-70% of patients will fail to respond to neo-CRT. Therefore, the identification of biomarkers indicative of patient response to treatment has significant clinical implications in the stratification of patient treatment. Furthermore, understanding the molecular mechanisms underpinning tumour response and resistance to neo-CRT will contribute towards the identification of novel therapeutic targets for enhancing OAC sensitivity to CRT. MicroRNAs (miRNA/miR) function to regulate gene and protein expression and play a causal role in cancer development and progression. MiRNAs have also been identified as modulators of key cellular pathways associated with resistance to CRT. Here, to identify miRNAs associated with resistance to CRT, pre-treatment diagnostic biopsy specimens from patients with OAC were analysed using miRNA-profiling arrays. In pre-treatment biopsies miR-330-5p was the most downregulated miRNA in patients who subsequently failed to respond to neo-CRT. The role of miR-330 as a potential modulator of tumour response and sensitivity to CRT in OAC was further investigated in vitro. Through vector-based overexpression the E2F1/p-AKT survival pathway, as previously described, was confirmed as a target of miR-330 regulation. However, miR-330-mediated alterations to the E2F1/p-AKT pathway were insufficient to significantly alter cellular sensitivity to chemotherapy (cisplatin and 5-flurouracil). In contrast, silencing of miR-330-5p enhanced, albeit subtly, cellular resistance to clinically relevant doses of radiation. This study highlights the need for further investigation into the potential of miR-330-5p as a predictive biomarker of patient sensitivity to neo-CRT and as a novel therapeutic target for manipulating cellular sensitivity to neo-CRT in patients with OAC
Minimal Universal Two-qubit Quantum Circuits
We give quantum circuits that simulate an arbitrary two-qubit unitary
operator up to global phase. For several quantum gate libraries we prove that
gate counts are optimal in worst and average cases. Our lower and upper bounds
compare favorably to previously published results. Temporary storage is not
used because it tends to be expensive in physical implementations.
For each gate library, best gate counts can be achieved by a single universal
circuit. To compute gate parameters in universal circuits, we only use
closed-form algebraic expressions, and in particular do not rely on matrix
exponentials. Our algorithm has been coded in C++.Comment: 8 pages, 2 tables and 4 figures. v3 adds a discussion of asymetry
between Rx, Ry and Rz gates and describes a subtle circuit design problem
arising when Ry gates are not available. v2 sharpens one of the loose bounds
in v1. Proof techniques in v2 are noticeably revamped: they now rely less on
circuit identities and more on directly-computed invariants of two-qubit
operators. This makes proofs more constructive and easier to interpret as
algorithm
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