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Measurements of inclusive and differential fiducial cross-sections of $tbar{t}gamma$ production in leptonic final states at $sqrt{s}$ = 13 TeV

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 Publication date 2019
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The latest results of the ATLAS experiment for the production of a top-quark pair in association with a photon using proton-proton collision data from the LHC at a centre-of-mass energy of 13 TeV are summarised here. This includes inclusive and differential cross-sections measurements performed in single-lepton and dilepton final states in a fiducial volume corresponding to the experimental acceptance.



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Production cross-sections of prompt charm mesons are measured with the first data from $pp$ collisions at the LHC at a centre-of-mass energy of $13,mathrm{TeV}$. The data sample corresponds to an integrated luminosity of $4.98 pm 0.19,mathrm{pb}^{-1}$ collected by the LHCb experiment. The production cross-sections of $D^{0}$, $D^{+}$, $D_{s}^{+}$, and $D^{*+}$ mesons are measured in bins of charm meson transverse momentum, $p_{mathrm{T}}$, and rapidity, $y$, and cover the range $0 < p_{mathrm{T}} < 15,mathrm{GeV}/c$ and $2.0 < y < 4.5$. The inclusive cross-sections for the four mesons, including charge conjugation, within the range of $1 < p_{mathrm{T}} < 8,mathrm{GeV}/c$ are found to be begin{equation} sigma(pp to D^{0} X) = 2072 pm 2 pm 124,mumathrm{b} sigma(pp to D^{+} X) = 834 pm 2 pm phantom{1}78,mumathrm{b} sigma(pp to D_{s}^{+} X) = 353 pm 9 pm phantom{1}76,mumathrm{b} sigma(pp to D^{*+} X) = 784 pm 4 pm phantom{1}87,mumathrm{b} end{equation} where the uncertainties are due to statistical and systematic uncertainties, respectively.
The top quark pair production $sigma_{tbar{t}}$ is measured in pp collisions at a center-of-mass energy of 5.02 TeV. The analyzed data have been collected by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 27.4 /pb. The measurement is performed by analyzing events with at least one charged lepton. The measured cross section is 69.5 $pm$ 8.4 pb. The result is in agreement with the expectation from the standard model. The impact of the presented measurement on the gluon distribution function is illustrated through a quantum chromodynamic analysis at next-to-next-to-leading order.
Production cross-sections of prompt charm mesons are measured using data from $pp$ collisions at the LHC at a centre-of-mass energy of $5,$TeV. The data sample corresponds to an integrated luminosity of $8.60pm0.33,$pb$^{-1}$ collected by the LHCb experiment. The production cross-sections of $D^0$, $D^+$, $D_s^+$, and $D^{*+}$ mesons are measured in bins of charm meson transverse momentum, $p_{text{T}}$, and rapidity, $y$. They cover the rapidity range $2.0<y<4.5$ and transverse momentum ranges $0 < p_{text{T}} < 10, text{GeV}/c$ for $D^0$ and $D^+$ and $1 < p_{text{T}} < 10, text{GeV}/c$ for $D_s^+$ and $D^{*+}$ mesons. The inclusive cross-sections for the four mesons, including charge-conjugate states, within the range of $1 < p_{text{T}} < 8, text{GeV}/c$ are determined to be sigma(pprightarrow D^0 X) = 1004 pm 3 pm 54,mutext{b} sigma(pprightarrow D^+ X) = 402 pm 2 pm 30,mutext{b} sigma(pprightarrow D_s^+ X) = 170 pm 4 pm 16,mutext{b} sigma(pprightarrow D^{*+} X)= 421 pm 5 pm 36,mutext{b} where the uncertainties are statistical and systematic, respectively.
The TOTEM collaboration has measured the elastic proton-proton differential cross section ${rm d}sigma/{rm d}t$ at $sqrt{s}=13$ TeV LHC energy using dedicated $beta^{*}=90$ m beam optics. The Roman Pot detectors were inserted to 10$sigma$ distance from the LHC beam, which allowed the measurement of the range $[0.04$ GeV$^{2}$$; 4 $GeV$^{2}$$]$ in four-momentum transfer squared $|t|$. The efficient data acquisition allowed to collect about 10$^{9}$ elastic events to precisely measure the differential cross-section including the diffractive minimum (dip), the subsequent maximum (bump) and the large-$|t|$ tail. The average nuclear slope has been found to be $B=(20.40 pm 0.002^{rm stat} pm 0.01^{rm syst})~$GeV$^{-2}$ in the $|t|$-range $0.04~$GeV$^{2}$ to $0.2~$GeV$^{2}$. The dip position is $|t_{rm dip}|=(0.47 pm 0.004^{rm stat} pm 0.01^{rm syst})~$GeV$^{2}$. The differential cross section ratio at the bump vs. at the dip $R=1.77pm0.01^{rm stat}$ has been measured with high precision. The series of TOTEM elastic pp measurements show that the dip is a permanent feature of the pp differential cross-section at the TeV scale.
In this paper we present a precise measurement of the total ZZ production cross section in pp collisions at {surd}s= 1.96 TeV, using data collected with the CDF II detector corresponding to an integrated luminosity of approximately 6 fb-1. The result is obtained by combining separate measurements in the four-charged (llll), and two-charged-lepton and two-neutral-lepton (llvv) decay modes of the Z. The combined measured cross section for pp {to} ZZ is 1.64^(+0.44)_(-0.38) pb. This is the most precise measurement of the ZZ production cross section in 1.96 TeV pp collisions to date.
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