7,837 research outputs found
Ab initio modeling of the energy landscape for screw dislocations in body-centered cubic high-entropy alloys
In traditional body-centered cubic (bcc) metals, the core properties of screw
dislocations play a critical role in plastic deformation at low temperatures.
Recently, much attention has been focused on refractory high-entropy alloys
(RHEAs), which also possess bcc crystal structures. However, unlike
face-centered cubic high-entropy alloys (HEAs), there have been far fewer
investigations on bcc HEAs, specifically on the possible effects of chemical
short-range order (SRO) in these multiple principal element alloys on
dislocation mobility. Here, using density functional theory, we investigate the
distribution of dislocation core properties in MoNbTaW RHEAs alloys, and how
they are influenced by SRO. The average values of the core energies in the RHEA
are found to be larger than those in the corresponding pure constituent bcc
metals, and are relatively insensitive to the degree of SRO. However, the
presence of SRO is shown to have a large effect on narrowing the distribution
of dislocation core energies and decreasing the spatial heterogeneity of
dislocation core energies in the RHEA. It is argued that the consequences for
the mechanical behavior of HEAs is a change in the energy landscape of the
dislocations which would likely heterogeneously inhibit their motion
Resummation Prediction on Higgs and Vector Boson Associated Production with a Jet Veto at the LHC
We investigate the resummation effects for the SM Higgs and vector boson
associated production at the LHC with a jet veto in soft-collinear effective
theory using "collinear anomalous" formalism. We calculate the jet vetoed
invariant mass distribution and the cross section for this process at
Next-to-Next-to-Leading-Logarithmic level, which are matched to the QCD
Next-to-Leading Order results, and compare the differences of the resummation
effects with different jet veto and jet radius . Our
results show that both resummation enhancement effects and the scale
uncertainties decrease with the increasing of jet veto and
jet radius , respectively. When GeV and ,
the resummation effects reduce the scale uncertainties of the Next-to-Leading
Order jet vetoed cross sections to about , which lead to increased
confidence on the theoretical predictions. Besides, after including resummation
effects, the PDF uncertainties of jet vetoed cross section are about .Comment: 22 pages, 10 figures and 2 tables; final version in JHE
Search for the signal of monotop production at the early LHC
We investigate the potential of the early LHC to discover the signal of
monotops, which can be decay products of some resonances in models such as
R-parity violating SUSY or SU(5), etc. We show how to constrain the parameter
space of the models by the present data of boson hadronic decay branching
ratio, mixing and dijet productions at the LHC. Then, we study
the various cuts imposed on the events, reconstructed from the hadronic final
states, to suppress backgrounds and increase the significance in detail. And we
find that in the hadronic mode the information from the missing transverse
energy and reconstructed resonance mass distributions can be used to specify
the masses of the resonance and the missing particle. Finally, we study the
sensitivities to the parameters at the LHC with =7 TeV and an
integrated luminosity of in detail. Our results show that the
early LHC may detect this signal at 5 level for some regions of the
parameter space allowed by the current data.Comment: 25 pages, 18 figures, 3 tables, version published in Phys.Rev.
Threshold Resummation for WZ and ZZ Pair Production at the LHC
We perform the threshold resummation for WZ and ZZ pair production at the
next-to-next-to-leading logarithmic accuracy in Soft-Collinear Effective Theory
at the LHC. Our results show that the resummation effects increase the total
cross sections by about 7% for ZZ production and 12% for WZ production
with$\sqrt{S}= 7,~8,~13 and 14 TeV, respectively, and the scale uncertainties
are significantly reduced. Besides, our numerical results are well consistent
with experimental data reported by the ATLAS and CMS collaborations.Comment: 14 pages, 8 figures, 2 tables, version published in Phys.Rev.
Soft gluon resummation in the signal-background interference process of
We present a precise theoretical prediction for the signal-background
interference process of , which is useful to constrain the
Higgs boson decay width and to measure Higgs couplings to the SM particles. The
approximate NNLO -factor is in the range of (),
depending on , at the 8 (13) TeV LHC. And the soft gluon resummation
can increase the approximate NNLO result by about at both the 8 TeV and
13 TeV LHC. The theoretical uncertainties including the scale, uncalculated
multi-loop amplitudes of the background and PDF are roughly
at . We also confirm that the approximate
-factors in the interference and the pure signal processes are the same.Comment: 18 pages, 9 figures; v2 published in JHE
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