The first double diffractive cross-section measurement in the very forward region has been carried out by the TOTEM experiment at the LHC with center-of-mass energy of sqrt(s)=7 TeV. By utilizing the very forward TOTEM tracking detectors T1 and T2, which extend up to |eta|=6.5, a clean sample of double diffractive pp events was extracted. From these events, we measured the cross-section sigma_DD =(116 +- 25) mub for events where both diffractive systems have 4.7 <|eta|_min < 6.5 .
We present an estimate of survival probability from an eikonal mini- jet model implemented with a proposal for soft gluon resummation to all orders. We compare it with experimental data for diffractive di-jet production from LHC experiments, CMS and ATLAS, both at LO and NLO order.
We study the precision with which the t-channel single top quark production cross section is expected to be measured in future LHC runs at 14 TeV. The single top final state has a lepton and neutrino from the top quark decay plus two jets, one of which is required to be b-tagged. This measurement is done in the context of the Snowmass 2013 study for the low-luminosity 14 TeV and the high-luminosity 14 TeV LHC as well as for high-luminosity 33 TeV LHC.
The associated production of a Z boson or an off-shell photon $gamma^*$ with a bottom quark in the forward region is studied using proton-proton collisions at a centre-of-mass energy of $7{mathrm{,Tekern -0.1em V}}$. The Z bosons are reconstructed in the ${text{Z}/gamma^*}!rightarrow{mu^{+}mu^{-}}$ final state from muons with a transverse momentum larger than $20{mathrm{,Gekern -0.1em V}}$, while two transverse momentum thresholds are considered for jets ($10{mathrm{,Gekern -0.1em V}}$ and $20{mathrm{,Gekern -0.1em V}}$). Both muons and jets are reconstructed in the pseudorapidity range $2.0 < eta < 4.5$. The results are based on data corresponding to $1.0{,mbox{fb}^{-1}}$ recorded in 2011 with the LHCb detector. The measurement of the Z+b-jet cross-section is normalized to the Z+jet cross-section. The measured cross-sections are begin{equation*} sigma(text{$text{Z}/gamma^*(mu^{+}mu^{-})$+b-jet}) = 295 pm 60~(text{stat}) pm 51~(text{syst}) pm 10~(text{lumi}) {,mbox{fb}} end{equation*} for ${p_{rm T}}$(jet)$>10{mathrm{,Gekern -0.1em V}}$, and begin{equation*} sigma(text{$text{Z}/gamma^*(mu^{+}mu^{-})$+b-jet}) = 128 pm 36~(text{stat}) pm 22~(text{syst}) pm 5~(text{lumi}) {,mbox{fb}} end{equation*} for ${p_{rm T}}$(jet)$>20{mathrm{,Gekern -0.1em V}}$.
Feasibility studies of an observation of the exclusive diffractive bremsstrahlung in proton-proton scattering at the LHC are reported. A simplified approach to the photon and the scattered proton energy reconstruction is used. The background influence is discussed.
A measurement of the production cross-section for $Z$ bosons that decay to muons is presented. The data were recorded by the LHCb detector during $pp$ collisions at a centre-of-mass energy of 7 TeV, and correspond to an integrated luminosity of 1.0 fb$^{-1}$. The cross-section is measured for muons in the pseudorapidity range $2.0 < eta < 4.5$ with transverse momenta $p_{T} > 20$ GeV/c. The dimuon mass is restricted to $60 < M_{mu^{+}mu^{-}} < 120$ GeV/c$^{2}$. The measured cross-section is $$sigma_{Zrightarrowmu^{+}mu^{-}} = (76.0 pm 0.3 pm 0.5 pm 1.0 pm 1.3) , text{pb}$$ where the uncertainties are due to the sample size, systematic effects, the beam energy and the luminosity. This result is in good agreement with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics. The cross-section is also measured differentially as a function of kinematic variables of the $Z$ boson. Ratios of the production cross-sections of electroweak bosons are presented using updated LHCb measurements of $W$ boson production. A precise test of the Standard Model is provided by the measurement of the ratio $$frac{sigma_{W^{+}rightarrowmu^{+} u_{mu}} + sigma_{W^{-}rightarrowmu^{-}bar{ u}_{mu}}}{sigma_{Zrightarrowmu^{+}mu^{-}}} = 20.63pm0.09pm0.12pm0.05,$$ where the uncertainty due to luminosity cancels.
TOTEM Collaboration: G. Antchev
,P. Aspell
,I. Atanassov
.
(2013)
.
"Double diffractive cross-section measurement in the forward region at LHC"
.
Tamas Csorgo
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