756 research outputs found
Sequential Flavour Symmetry Breaking
The gauge sector of the Standard Model (SM) exhibits a flavour symmetry which
allows for independent unitary transformations of the fermion multiplets. In
the SM the flavour symmetry is broken by the Yukawa couplings to the Higgs
boson, and the resulting fermion masses and mixing angles show a pronounced
hierarchy. In this work we connect the observed hierarchy to a sequence of
intermediate effective theories, where the flavour symmetries are broken in a
step-wise fashion by vacuum expectation values of suitably constructed spurion
fields. We identify the possible scenarios in the quark sector and discuss some
implications of this approach.Comment: 22 pages latex, no figure
Extracting V_{ub} Without Recourse to Structure Functions
We present a closed form expression for |V_{ub}|^2/ |V_{tb} V_{ts}^*|^2 in
terms of the endpoint photon and lepton spectra from the inclusive decays B ->
X_s\gamma and B -> X_u\ell\nu, respectively, which includes the resummation of
the endpoint logs at next to leading order and is completely independent of the
B meson structure function. The use of this expression for extracting V_{ub}
would eliminate the large systematic errors usually incurred due to the
modeling of the heavy quarks' Fermi motion.Comment: 20 pages, no figures, minor typos correcte
decays in the Left-Right Symmetric Model
We consider decays in the Left-Right Symmetric Model. Values
of observables sensitive to chiral structure such as the polarization
in the decays and the mixing-induced CP
asymmetries in the decays can deviate in the LRSM
significantly from the SM values. The combined analysis of and
as well as can be used to determine the
model parameters.Comment: 16 pages with 7 figures, Version to be published in PR
Cometary dust collected by MIDAS on board Rosetta II. Particle shape descriptors and pristineness evaluation
The MIDAS (Micro-Imaging Dust Analysis System) atomic force microscope on
board the Rosetta comet orbiter investigated and measured the 3D topography of
a few hundred nm to tens of m sized dust particles of
67P/Churyumov-Gerasimenko with resolutions down to a few nanometers, giving
insights into the physical processes of our early Solar System. We analyze the
shapes of the cometary dust particles collected by MIDAS on the basis of a
recently updated particle catalog with the aim to determine which structural
properties remained pristine. We develop a set of shape descriptors and metrics
such as aspect ratio, elongation, circularity, convexity, and particle
surface/volume distribution, which can be used to describe the distribution of
particle shapes. Furthermore, we compare the structure of the MIDAS dust
particles and the clusters in which the particles were deposited to those found
in previous laboratory experiments and by Rosetta/COSIMA. Finally, we combine
our findings to calculate a pristineness score for MIDAS particles and
determine the most pristine particles and their properties. We find that the
morphological properties of all cometary dust particles at the micrometer scale
are surprisingly homogeneous despite originating from diverse cometary
environments (e.g., different collection targets that are associated with
cometary activities/source regions and collection velocities/periods). We next
find that the types of clusters found by MIDAS show good agreement with those
defined by previous laboratory experiments, however, there are some differences
to those found by Rosetta/COSIMA. Based on our result, we rate 19 out of 1082
MIDAS particles at least moderately pristine, i.e., they are not substantially
flattened by impact, not fragmented, and/or not part of a fragmentation
cluster.Comment: 40 pages, 31 figures, 1 online tabl
NRG Oncology/RTOG 0921: A phase 2 study of postoperative intensity-modulated radiotherapy with concurrent cisplatin and bevacizumab followed by carboplatin and paclitaxel for patients with endometrial cancer.
BACKGROUND: The current study was conducted to assess acute and late adverse events (AEs), overall survival (OS), pelvic failure, regional failure, distant failure, and disease-free survival in a prospective phase 2 clinical trial of bevacizumab and pelvic intensity-modulated radiotherapy (IMRT) with chemotherapy in patients with high-risk endometrial cancer.
METHODS: Patients underwent a hysterectomy and lymph node removal, and had ≥1 of the following high-risk factors: grade 3 carcinoma with \u3e50% myometrial invasion, grade 2 or 3 disease with any cervical stromal invasion, or known extrauterine extension confined to the pelvis. Treatment included pelvic IMRT and concurrent cisplatin on days 1 and 29 of radiation and bevacizumab (at a dose of 5 mg/kg on days 1, 15, and 29 of radiation) followed by adjuvant carboplatin and paclitaxel for 4 cycles. The primary endpoint was grade ≥3 AEs occurring within the first 90 days (toxicity was graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]).
RESULTS: A total of 34 patients were accrued from November 2009 through December 2011, 30 of whom were eligible and received study treatment. Seven of 30 patients (23.3%; 1-sided 95% confidence interval, 10.6%-36.0%) developed grade ≥3 treatment-related nonhematologic toxicities within 90 days; an additional 6 patients experienced grade ≥3 toxicities between 90 and 365 days after treatment. The 2-year OS rate was 96.7% and the disease-free survival rate was 79.1%. No patient developed a within-field pelvic failure and no patients with International Federation of Gynecology and Obstetrics stage I to IIIA disease developed disease recurrence after a median follow-up of 26 months.
CONCLUSIONS: Postoperative bevacizumab added to chemotherapy and pelvic IMRT appears to be well tolerated and results in high OS rates at 2 years for patients with high-risk endometrial carcinoma
Brief review on semileptonic B decays
We concisely review semileptonic B decays, focussing on recent progress on
both theoretical and experimental sides.Comment: 18 pages, 2 figures; version to be published in Mod. Phys. Lett.
Heavy Quarkonium Effective Theory
We formulate a QCD-based effective theory approach to heavy quarkonia-like
systems as and resonances and states. We apply
the method to inclusive decays, working out a few examples in detail.Comment: 52 pages, LaTeX, 3 uuencoded and compressed figures, uses epsf.sty,
CERN-TH.7468/9
Enhancements in Mass Transfer for Carbon Capture Solvents Part I: Homogeneous Catalyst
The novel small molecule carbonic anhydrase (CA) mimic [CoIII(Salphen-COO−)Cl]HNEt3 (1), was synthesized as an additive for increasing CO2 absorption rates in amine-based post-combustion carbon capture processes (CCS), and its efficacy was verified. 1 was designed for use in a kinetically slow but thermally stable blended solvent, containing the primary amines 1-amino-2-propanol (A2P) and 2-amino-2-methyl-1-propanol (AMP). Together, the A2P/AMP solvent and 1 reduce the overall energy penalty associated with CO2 capture from coal-derived flue gas, relative to the baseline solvent MEA. 1 is also effective at increasing absorption kinetics of kinetically fast solvents, such as MEA, which can reduce capital costs by requiring a smaller absorber tower. The transition from catalyst testing under idealized laboratory conditions, to process relevant lab- and bench-scale testing adds many additional variables that are not well understood and rarely discussed. The stepwise testing of both 1 and the novel A2P/AMP solvent blend is described through a transition process that identifies many of these process and evaluation challenges not often addressed when designing a chemical or catalytic additive for industrial CCS systems, where consideration of solvent chemistry is typically the primary goal
Status and overview of development of the Silicon Pixel Detector for the PHENIX experiment at the BNL RHIC
We have developed a silicon pixel detector to enhance the physics
capabilities of the PHENIX experiment. This detector, consisting of two layers
of sensors, will be installed around the beam pipe at the collision point and
covers a pseudo-rapidity of | \eta | < 1.2 and an azimuth angle of | \phi | ~
2{\pi}. The detector uses 200 um thick silicon sensors and readout chips
developed for the ALICE experiment. In order to meet the PHENIX DAQ readout
requirements, it is necessary to read out 4 readout chips in parallel. The
physics goals of PHENIX require that radiation thickness of the detector be
minimized. To meet these criteria, the detector has been designed and
developed. In this paper, we report the current status of the development,
especially the development of the low-mass readout bus and the front-end
readout electronics.Comment: 9 pages, 8 figures and 1 table in DOCX (Word 2007); PIXEL 2008
workshop proceedings, will be published in the Proceedings Section of
JINST(Journal of Instrumentation
Application of heavy-quark effective theory to lattice QCD: I. Power Corrections
Heavy-quark effective theory (HQET) is applied to lattice QCD with Wilson
fermions at fixed lattice spacing a. This description is possible because
heavy-quark symmetries are respected. It is desirable because the ultraviolet
cutoff in current numerical work and the heavy-quark mass are
comparable. Effects of both short distances, a and , are captured fully
into coefficient functions, which multiply the operators of the usual HQET.
Standard tools of HQET are used to develop heavy-quark expansions of lattice
observables and, thus, to propagate heavy-quark discretization errors. Three
explicit examples are given: namely, the mass, decay constant, and semileptonic
form factors of heavy-light mesons.Comment: 41 pp., no figs; Phys Rev D version, improving argument that an HQET
holds for all m_Q
- …