A new standard is currently being developed under the auspices of ECISS/TC 101 WG1 for the small punch testing technique for the estimation of both tensile and creep properties. Annex G of the new ...standard is covering the assessment and evaluation of small punch creep (SPC) data. The main challenge for estimating uniaxial creep properties from SPC data is the force to equivalent stress conversion between SPC and uniaxial creep tests. In this work a range of SPC assessment methodologies, benchmarked for the standard, are compared for verifying the best practice used in the standard. The estimated equivalent stresses for SPC are compared to uniaxial creep stresses at equal rupture times, using three alternative models. In-depth analyses are performed on SPC and uniaxial creep data for P92, F92 and 316 L steel tested within an inter-laboratory round robin. The formulation for SPC equivalent creep strain rate in the standard is also assessed.
A
bstract
A determination of the top-quark mass is presented using 20.2 fb
−
1
of 8 TeV proton-proton collision data produced by the Large Hadron Collider and collected by the ATLAS experiment. The ...normalised differential cross section of top-quark pair production in association with an energetic jet is measured in the lepton+jets final state and unfolded to parton and particle levels. The unfolded distribution at parton level can be described using next-to-leading-order QCD predictions in terms of either the top-quark pole mass or the running mass as defined in the (modified) minimal subtraction scheme. A comparison between the experimental distribution and the theoretical prediction allows the top-quark mass to be extracted in the two schemes. The value obtained for the pole-mass scheme is:
m
t
pole
=
171.1
±
0.4
stat
±
0.9
syst
−
0.3
+
0.7
theo
GeV
The extracted value in the running-mass scheme is:
m
t
m
t
=
162.9
±
0.5
stat
±
1.0
syst
−
1.2
+
2.1
theo
GeV
.
The results for the top-quark mass using the two schemes are consistent, when translated from one scheme to the other.
This paper presents studies of Bose–Einstein correlations (BEC) in proton–proton collisions at a centre-of-mass energy of 13 TeV, using data from the ATLAS detector at the CERN Large Hadron Collider. ...Data were collected in a special low-luminosity configuration with a minimum-bias trigger and a high-multiplicity track trigger, accumulating integrated luminosities of 151
μ
b
-
1
and 8.4 nb
-
1
, respectively. The BEC are measured for pairs of like-sign charged particles, each with
|
η
|
<
2.5
, for two kinematic ranges: the first with particle
p
T
>
100
MeV and the second with particle
p
T
>
500
MeV. The BEC parameters, characterizing the source radius and particle correlation strength, are investigated as functions of charged-particle multiplicity (up to 300) and average transverse momentum of the pair (up to 1.5 GeV). The double-differential dependence on charged-particle multiplicity and average transverse momentum of the pair is also studied. The BEC radius is found to be independent of the charged-particle multiplicity for high charged-particle multiplicity (above 100), confirming a previous observation at lower energy. This saturation occurs independent of the transverse momentum of the pair.
The fraction of $χ$c1 and $χ$c2 decays in the prompt $J/ψ$ yield, $F$χc→J/ψ = σχc→J/ψ/σJ/ψ, is measured by the LHCb detector in $p$ Pb collisions at $\sqrt{^sNN}$ = 8.16 $TeV$. The study covers the ...forward (1.5 < y* < 4.0) and backward (-5.0 < y* < - 2.5) rapidity regions, where y* is the $J/ψ$ rapidity in the nucleon-nucleon center-of-mass system. Forward and backward rapidity samples correspond to integrated luminosities of 13.6 ± 0.3 and 20.8 ± 0.5 nb-1, respectively. The result is presented as a function of the $J/ψ$ transverse momentum $p$T,J/ψ in the range 1 < $p$T,J/ψ < 20 $GeV$ /c. The $F$χc→J/ψ fraction at forward rapidity is compatible with the LHCb measurement performed in $pp$ collisions at $\sqrt{s}$ = 7 $TeV$, whereas the result at backward rapidity is $2.4σ$ larger than in the forward region for 1 < $p$T,J/ψ < 3 $GeV$ /c. The increase of $F$χc→J/ψ at low pT,J/ψ at backward rapidity is compatible with the suppression of the $ψ$ ($2S$) contribution to the prompt $J/ψ$ yield. The lack of in-medium dissociation of $χ$c states observed in this study sets an upper limit of 180 MeV on the free energy available in these $pPb$ collisions to dissociate or inhibit charmonium state formation.
A bstract The ratio of production cross-sections of ψ (2 S ) over J/ψ mesons as a function of charged-particle multiplicity in proton-proton collisions at a centre-of-mass energy $$ \sqrt{s} $$ s = ...13 TeV is measured with a data sample collected by the LHCb detector, corresponding to an integrated luminosity of 658 pb − 1 . The ratio is measured for both prompt and non-prompt ψ (2 S ) and J/ψ mesons. When there is an overlap between the rapidity ranges over which multiplicity and charmonia production are measured, a multiplicity-dependent modification of the ratio is observed for prompt mesons. No significant multiplicity dependence is found when the ranges do not overlap. For non-prompt production, the ψ (2 S )-to- J/ψ production ratio is roughly independent of multiplicity, irrespective of the rapidity range over which the multiplicity is measured. The results are compared to predictions of the co-mover model and agree well except in the low multiplicity region. The ratio of production cross-sections of ψ (2 S ) over J/ψ mesons are cross-checked with other measurements in di-lepton channels and found to be compatible.
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