416 research outputs found
СТРУКТУРНО-ВЕЩЕСТВЕННАЯ МОДЕЛЬ СТАНОВЛЕНИЯ КИМБЕРЛИТОВОЙ ТРУБКИ НЮРБИНСКАЯ (СРЕДНЕ-МАРХИНСКИЙ РАЙОН ЯКУТСКОЙ АЛМАЗОНОСНОЙ ПРОВИНЦИИ)
The paper presents the results of comprehensive study of the primary diamond deposit of the Nyurbinskaya pipe in the Yakutian diamondiferous province. It is established, that the pipe is confined to the fault junction of four directions and is composed of the kimberlite of four phases. Analysis of different faults and tectonic fracturing allowed to reconstruct the tectonic stress fields acting at the stage of the kimberlite body formation and to determine their occurrence sequence in time. The data obtained about regularities of the Nyurbinskaya pipe compositional structure and results of geologo-structural studies are combined in a single structural-compositional model of the deposit formation. Peculiarities of the fault network operation during the deposit formation stage are confirmed by experimental results using polarization-optical method. The model allowed to formulate the basic structural characteristics of the prospecting works object within which the formation of kimberlite body type of the Nyurbinskaya pipe is possible and to determine the elements of the fault network which are promising for the kimberlite pipes discovery.В статье представлены результаты комплексного изучения коренного месторождения алмазов трубка Нюрбинская. Установлено, что трубка приурочена к узлу разломов четырех направлений и сложена кимберлитами четырех фаз. Анализ разноранговых разрывных нарушений и тектонической трещиноватости позволил восстановить поля тектонических напряжений, действовавшие на этапе формирования кимберлитового тела и определить последовательность их проявления во времени. Полученные данные о закономерностях вещественного строения трубки Нюрбинской и результаты геолого-структурных исследований объединены в рамках единой структурно-вещественной модели формирования месторождения. Особенности функционирования разрывной сети на этапе формирования месторождения подтверждены результатами экспериментов с использованием поляризационно-оптического метода. Полученная модель позволила сформулировать признаки, определяющие основные структурные характеристики объекта поисковых работ, в пределах которого возможно формирование кимберлитовых тел типа трубки Нюрбинской, и на их основании выделить те элементы разломной сети (разломные узлы), которые являются перспективными для обнаружения кимберлитовых трубок
Multijet production in neutral current deep inelastic scattering at HERA and determination of α_{s}
Multijet production rates in neutral current deep inelastic scattering have been measured in the range of exchanged boson virtualities 10 5 GeV and –1 < η_{LAB}^{jet} < 2.5. Next-to-leading-order QCD calculations describe the data well. The value of the strong coupling constant α_{s} (M_{z}), determined from the ratio of the trijet to dijet cross sections, is α_{s} (M_{z}) = 0.1179 ± 0.0013 (stat.)_{-0.0046}^{+0.0028}(exp.)_{-0.0046}^{+0.0028}(th.)
High-E_T dijet photoproduction at HERA
The cross section for high-E_T dijet production in photoproduction has been
measured with the ZEUS detector at HERA using an integrated luminosity of 81.8
pb-1. The events were required to have a virtuality of the incoming photon,
Q^2, of less than 1 GeV^2 and a photon-proton centre-of-mass energy in the
range 142 < W < 293 GeV. Events were selected if at least two jets satisfied
the transverse-energy requirements of E_T(jet1) > 20 GeV and E_T(jet2) > 15 GeV
and pseudorapidity requirements of -1 < eta(jet1,2) < 3, with at least one of
the jets satisfying -1 < eta(jet) < 2.5. The measurements show sensitivity to
the parton distributions in the photon and proton and effects beyond
next-to-leading order in QCD. Hence these data can be used to constrain further
the parton densities in the proton and photon.Comment: 36 pages, 13 figures, 20 tables, including minor revisions from
referees. Accepted by Phys. Rev.
An NLO QCD analysis of inclusive cross-section and jet-production data from the ZEUS experiment
The ZEUS inclusive differential cross-section data from HERA, for charged and
neutral current processes taken with e+ and e- beams, together with
differential cross-section data on inclusive jet production in e+ p scattering
and dijet production in \gamma p scattering, have been used in a new NLO QCD
analysis to extract the parton distribution functions of the proton. The input
of jet data constrains the gluon and allows an accurate extraction of
\alpha_s(M_Z) at NLO;
\alpha_s(M_Z) = 0.1183 \pm 0.0028(exp.) \pm 0.0008(model)
An additional uncertainty from the choice of scales is estimated as \pm
0.005. This is the first extraction of \alpha_s(M_Z) from HERA data alone.Comment: 37 pages, 14 figures, to be submitted to EPJC. PDFs available at
http://durpdg.dur.ac.uk/hepdata in LHAPDFv
Measurement of event shapes in deep inelastic scattering at HERA
Inclusive event-shape variables have been measured in the current region of
the Breit frame for neutral current deep inelastic ep scattering using an
integrated luminosity of 45.0 pb^-1 collected with the ZEUS detector at HERA.
The variables studied included thrust, jet broadening and invariant jet mass.
The kinematic range covered was 10 < Q^2 < 20,480 GeV^2 and 6.10^-4 < x < 0.6,
where Q^2 is the virtuality of the exchanged boson and x is the Bjorken
variable. The Q dependence of the shape variables has been used in conjunction
with NLO perturbative calculations and the Dokshitzer-Webber non-perturbative
corrections (`power corrections') to investigate the validity of this approach.Comment: 7+25 pages, 6 figure
Dissociation of virtual photons in events with a leading proton at HERA
The ZEUS detector has been used to study dissociation of virtual photons in
events with a leading proton, gamma^* p -> X p, in e^+p collisions at HERA. The
data cover photon virtualities in two ranges, 0.03<Q^2<0.60 GeV^2 and 2<Q^2<100
GeV^2, with M_X>1.5 GeV, where M_X is the mass of the hadronic final state, X.
Events were required to have a leading proton, detected in the ZEUS leading
proton spectrometer, carrying at least 90% of the incoming proton energy. The
cross section is presented as a function of t, the squared four-momentum
transfer at the proton vertex, Phi, the azimuthal angle between the positron
scattering plane and the proton scattering plane, and Q^2. The data are
presented in terms of the diffractive structure function, F_2^D(3). A
next-to-leading-order QCD fit to the higher-Q^2 data set and to previously
published diffractive charm production data is presented
Inclusive jet cross sections and dijet correlations in photoproduction at HERA
Inclusive jet cross sections in photoproduction for events containing a
meson have been measured with the ZEUS detector at HERA using an integrated
luminosity of . The events were required to have a
virtuality of the incoming photon, , of less than 1 GeV, and a
photon-proton centre-of-mass energy in the range . The measurements are compared with next-to-leading-order (NLO) QCD
calculations. Good agreement is found with the NLO calculations over most of
the measured kinematic region. Requiring a second jet in the event allowed a
more detailed comparison with QCD calculations. The measured dijet cross
sections are also compared to Monte Carlo (MC) models which incorporate
leading-order matrix elements followed by parton showers and hadronisation. The
NLO QCD predictions are in general agreement with the data although differences
have been isolated to regions where contributions from higher orders are
expected to be significant. The MC models give a better description than the
NLO predictions of the shape of the measured cross sections.Comment: 43 pages, 12 figures, charm jets ZEU
Measurement of (anti)deuteron and (anti)proton production in DIS at HERA
The first observation of (anti)deuterons in deep inelastic scattering at HERA
has been made with the ZEUS detector at a centre-of-mass energy of 300--318 GeV
using an integrated luminosity of 120 pb-1. The measurement was performed in
the central rapidity region for transverse momentum per unit of mass in the
range 0.3<p_T/M<0.7. The particle rates have been extracted and interpreted in
terms of the coalescence model. The (anti)deuteron production yield is smaller
than the (anti)proton yield by approximately three orders of magnitude,
consistent with the world measurements.Comment: 26 pages, 9 figures, 5 tables, submitted to Nucl. Phys.
Search for lepton-flavor violation at HERA
A search for lepton-flavor-violating interactions and has been performed with the ZEUS detector using the entire HERA I
data sample, corresponding to an integrated luminosity of 130 pb^{-1}. The data
were taken at center-of-mass energies, , of 300 and 318 GeV. No
evidence of lepton-flavor violation was found, and constraints were derived on
leptoquarks (LQs) that could mediate such interactions. For LQ masses below
, limits were set on , where
is the coupling of the LQ to an electron and a
first-generation quark , and is the branching ratio of
the LQ to the final-state lepton ( or ) and a quark . For
LQ masses much larger than , limits were set on the four-fermion
interaction term for LQs that couple to an electron and a quark
and to a lepton and a quark , where and are
quark generation indices. Some of the limits are also applicable to
lepton-flavor-violating processes mediated by squarks in -Parity-violating
supersymmetric models. In some cases, especially when a higher-generation quark
is involved and for the process , the ZEUS limits are the most
stringent to date.Comment: 37 pages, 10 figures, Accepted by EPJC. References and 1 figure (Fig.
6) adde
EMPOWER-lung 1: A randomized, open-label, multi-national, phase III trial of cemiplimab, a human PD-1 monoclonal antibody, versus chemotherapy in first-line treatment of advanced non-small cell lung cancer (NSCLC) with PD-L1 50%
Background: Most patients (pts) with NSCLC present with advanced disease at diagnosis. Systemic therapy with platinum-based doublet chemotherapy regimens has been the standard first-line treatment for pts with advanced NSCLC whose tumours do not have EGFR, ALK, or ROS 1 mutations, but there is a need for effective treatments to improve long-term survival. With the recognition that NSCLC tumours express PD-L1, checkpoint inhibitors are being investigated in several clinical trials. There is currently only one PD-1 inhibitor approved as monotherapy in first-line treatment of NSCLC with PD-L1 expression ≥50%. In a phase 1 dose escalation and NSCLC expansion cohort, cemiplimab (REGN2810), a human monoclonal anti-PD-1, has demonstrated antitumour activity with an acceptable safety profile in anti-PD-1 naïve, pre-treated pts with NSCLC.
Trial design: This is a randomised (1:1), multicentre, open-label, phase 3 study of cemiplimab versus platinum-based doublet chemotherapy in systemic treatment-naïve pts (≥18 years) with stage IIIB, IIIC or IV squamous or non-squamous NSCLC whose tumours express PD-L1 in ≥ 50% of tumour cells (NCT03088540)
- …