623 research outputs found
Probing Topcolor-Assisted Technicolor from Top-Charm Associated Production at LHC
We propose to probe the topcolor-assisted technicolor (TC2) model from the
top-charm associated productions at the LHC, which are highly suppressed in the
Standard Model. Due to the flavor-changing couplings of the top quark with the
scalars (top-pions and top-Higgs) in TC2 model, the top-charm associated
productions can occur via both the s-channel and t-channel parton processes by
exchanging a scalar field at the LHC. We examined these processes through Monte
Carlo simulation and found that they can reach the observable level at the LHC
in quite a large part of the parameter space of the TC2 model.Comment: Version to appear in PRD (Rapid Communication
Endonuclease heteroduplex mismatch cleavage for detecting mutation genetic variation of trypsin inhibitors in soybean
The objective of this work was to evaluate the genetic variation of trypsin inhibitor in cultivated (Glycine max L.) and wild (Glycine sofa Siebold & Zucc.) soybean varieties. Genetic variations of the Kunitz trypsin inhibitor, represented by a 21-kD protein (KTI), and of the Bowman-Birk trypsin chymotrypsin inhibitor (BBI) were evaluated in cultivated (G. max) and wild (G. sofa) soybean varieties. Endonuclease heteroduplex mismatch cleavage assays were performed to detect mutations in the KTI gene, with a single-stranded specific nuclease obtained from celery extracts (CEL I). The investigated soybean varieties showed low level of genetic variation in KTI and BBI. PCR-RFLP analysis divided the BBI-A type into subtypes A1 and A2, and showed that Tib type of KTI is the dominant type. Digestion with restriction enzymes was not able to detect differences between ti-null and other types of Ti alleles, while the endonuclease heteroduplex mismatch cleavage assay with CEL I could detect ti-null type. The digestion method with CEL I provides a simple and useful genetic tool for SNP analysis. The presented method can be used as a tool for fast and useful screening of desired genotypes in future breeding programs of soybean
Exceptionally Slow Rise in Differential Reflectivity Spectra of Excitons in GaN: Effect of Excitation-induced Dephasing
Femtosecond pump-probe (PP) differential reflectivity spectroscopy (DRS) and
four-wave mixing (FWM) experiments were performed simultaneously to study the
initial temporal dynamics of the exciton line-shapes in GaN epilayers. Beats
between the A-B excitons were found \textit{only for positive time delay} in
both PP and FWM experiments. The rise time at negative time delay for the
differential reflection spectra was much slower than the FWM signal or PP
differential transmission spectroscopy (DTS) at the exciton resonance. A
numerical solution of a six band semiconductor Bloch equation model including
nonlinearities at the Hartree-Fock level shows that this slow rise in the DRS
results from excitation induced dephasing (EID), that is, the strong density
dependence of the dephasing time which changes with the laser excitation
energy.Comment: 8 figure
Flavor changing single top quark production channels at e^+e^- colliders in the effective Lagrangian description
We perform a global analysis of the sensitivity of LEP2 and e^+e^- colliders
with a c.m. energy in the range 500 - 2000 GeV to new flavor-changing single
top quark production in the effective Lagrangian approach. The processes
considered are sensitive to new flavor-changing effective vertices such as Ztc,
htc, four-Fermi tcee contact terms as well as a right-handed Wtb coupling. We
show that e^+ e^- colliders are most sensitive to the physics responsible for
the contact tcee vertices. For example, it is found that the recent data from
the 189 GeV LEP2 run can be used to rule out any new flavor physics that can
generate these four-Fermi operators up to energy scales of \Lambda > 0.7 - 1.4
TeV, depending on the type of the four-Fermi interaction. We also show that a
corresponding limit of \Lambda > 1.3 - 2.5 and \Lambda > 17 - 27 TeV can be
reached at the future 200 GeV LEP2 run and a 1000 GeV e^+e^- collider,
respectively. We note that these limits are much stronger than the typical
limits which can be placed on flavor diagonal four-Fermi couplings. Similar
results hold for \mu^+\mu^- colliders and for tu(bar) associated production.
Finally we briefly comment on the necessity of measuring all flavor-changing
effective vertices as they can be produced by different types of heavy physics.Comment: 34 pages, plain latex, 7 figures embadded in the text using epsfig.
Added new references and discussions regarding their relevance to the paper.
Added more comments on the comparison between flavor-changing and
flavor-diagonal contact terms and on the importance of measuring the Ztc
verte
Avances en el estudio de las bases genéticas y organolépticas del cacao fino o de aroma en el Perú
Las variedades de cacao fino o de aroma en el Perú son utilizados para elaborar los mejores chocolates del
mundo por sus exquisitas y poco comunes características organolépticas, Estas características permiten que
el cacao peruano gane reconocimiento internacional y de ahí su gran valor económico. A pesar de esto,
poco se sabe sobre los componentes genéticos y/o ambientales que contribuyen a la exclusividad de este
valioso recurso económico. En el proyecto de investigación aplicada: “Estudio molecular de la diversidad
genética de los cacaos aromáticos en el Perú con fines del fortalecimiento de su competitividad y aumento
de la producción nacional de cacao de calidad”, financiado por Innóvate Perú del Ministerio de la
Producción, se tiene como objetivos determinar la variabilidad genética y caracterización organoléptica de
más de 100 tipos de cacao fino o de aroma que se cultivan a lo largo de las cinco principales regiones del
Perú (Amazonas, Cusco, San Martin, Piura y Huánuco). Adicionalmente, la Universidad Nacional Agraria
de la Selva en Tingo María y el Instituto de Investigaciones de la Amazonia Peruana en Tarapoto,
hospedarán bancos de germoplasma y de propagación de esquejes para la difusión y estudios de estos
valiosos recursos. Hasta inicios del 2017, ya se han recolectado más de 80 genotipos provenientes de las
cinco regiones. Protocolos para análisis sensoriales que cumplan los más rigurosos estándares
internacionales se han venido estableciendo. Por otro lado, técnicas de marcadores moleculares usando
marcadores de DNA tipo SSR y SNPs, seguido por secuenciamiento de ADN, se vienen estableciendo.
Estudios de asociación de fenotipo-genotipo formarán parte del conocimiento generado en este proyecto.
Adicionalmente, estos conocimientos permitirán generar información genómica valiosa para salvaguardar
nuestra biodiversidad nativa, otorgándole a los productores y sus asociaciones de herramientas para
proteger sus recursos genéticos y a los potenciales mejoradores de cacao más luces en cuanto a la asociación
genotipo-calidad. Se espera que a fin del proyecto, se cuente con los resultados de genotipificación de más
de 100 genotipos de cacao fino o de aroma y mediante el resecuenciamiento se revelen SNPs particulares
para cada grupo genético en cada región muestreada
Grain Surface Models and Data for Astrochemistry
AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions
Search for Higgs bosons decaying to tautau pairs in ppbar collisions at sqrt(s) = 1.96 TeV
We present a search for the production of neutral Higgs bosons decaying into
tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The
data, corresponding to an integrated luminosity of 5.4 fb-1, were collected by
the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the
95% C.L. on the product of production cross section and branching ratio for a
scalar resonance decaying into tautau pairs, and we then interpret these limits
as limits on the production of Higgs bosons in the minimal supersymmetric
standard model (MSSM) and as constraints in the MSSM parameter space.Comment: 7 pages, 5 figures, submitted to PL
Measurement of the photon-jet production differential cross section in collisions at \sqrt{s}=1.96~\TeV
We present measurements of the differential cross section dsigma/dpT_gamma
for the inclusive production of a photon in association with a b-quark jet for
photons with rapidities |y_gamma|< 1.0 and 30<pT_gamma <300 GeV, as well as for
photons with 1.5<|y_gamma|< 2.5 and 30< pT_gamma <200 GeV, where pT_gamma is
the photon transverse momentum. The b-quark jets are required to have pT>15 GeV
and rapidity |y_jet| < 1.5. The results are based on data corresponding to an
integrated luminosity of 8.7 fb^-1, recorded with the D0 detector at the
Fermilab Tevatron Collider at sqrt(s)=1.96 TeV. The measured cross
sections are compared with next-to-leading order perturbative QCD calculations
using different sets of parton distribution functions as well as to predictions
based on the kT-factorization QCD approach, and those from the Sherpa and
Pythia Monte Carlo event generators.Comment: 10 pages, 9 figures, submitted to Phys. Lett.
Limits on anomalous trilinear gauge boson couplings from WW, WZ and Wgamma production in pp-bar collisions at sqrt{s}=1.96 TeV
We present final searches of the anomalous gammaWW and ZWW trilinear gauge
boson couplings from WW and WZ production using lepton plus dijet final states
and a combination with results from Wgamma, WW, and WZ production with leptonic
final states. The analyzed data correspond to up to 8.6/fb of integrated
luminosity collected by the D0 detector in pp-bar collisions at sqrt{s}=1.96
TeV. We set the most stringent limits at a hadron collider to date assuming two
different relations between the anomalous coupling parameters
Delta\kappa_\gamma, lambda, and Delta g_1^Z for a cutoff energy scale Lambda=2
TeV. The combined 68% C.L. limits are -0.057<Delta\kappa_\gamma<0.154,
-0.015<lambda<0.028, and -0.008<Delta g_1^Z<0.054 for the LEP parameterization,
and -0.007<Delta\kappa<0.081 and -0.017<lambda<0.028 for the equal couplings
parameterization. We also present the most stringent limits of the W boson
magnetic dipole and electric quadrupole moments.Comment: 10 pages, 5 figures, submitted to PL
Measurement of three-jet differential cross sections d sigma-3jet / d M-3jet in p anti-p collisions at sqrt(s)=1.96 TeV
We present the first measurement of the inclusive three-jet differential
cross section as a function of the invariant mass of the three jets with the
largest transverse momenta in an event in p anti-p collisions at sqrt(s) = 1.96
TeV. The measurement is made in different rapidity regions and for different
jet transverse momentum requirements and is based on a data set corresponding
to an integrated luminosity of 0.7 fb^{-1} collected with the D0 detector at
the Fermilab Tevatron Collider. The results are used to test the three-jet
matrix elements in perturbative QCD calculations at next-to-leading order in
the strong coupling constant. The data allow discrimination between
parametrizations of the parton distribution functions of the proton.Comment: 10 pages, 4 figures, 2 tables, submitted to Phys. Lett. B, corrected
chi2 values for NNPD
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