scholarly journals A search for narrow resonances in proton-proton collisions at 53 GeV centre-of-mass energy

1976 ◽  
Vol 114 (3) ◽  
pp. 365-379 ◽  
Author(s):  
M.G. Albrow ◽  
B. Alper ◽  
J. Armitage ◽  
D. Aston ◽  
P. Benz ◽  
...  
Keyword(s):  
Centre Of Mass ◽  
Mass Energy ◽  
Proton Proton ◽  
Proton Collisions ◽  
Proton Proton Collisions

scholarly journals Observation of the decay $$ {\Lambda}_{\mathrm{b}}^0 $$ → χc1pπ−

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Branching Fractions ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Proton Proton ◽  
Proton Collisions ◽  
Lhcb Detector ◽  
Using Data ◽  
Cabibbo Suppressed ◽  
First Time ◽  
Proton Proton Collisions

Abstract The Cabibbo-suppressed decay $$ {\Lambda}_{\mathrm{b}}^0 $$ Λ b 0 → χc1pπ− is observed for the first time using data from proton-proton collisions corresponding to an integrated luminosity of 6 fb−1, collected with the LHCb detector at a centre-of-mass energy of 13 TeV. Evidence for the $$ {\Lambda}_{\mathrm{b}}^0 $$ Λ b 0 → χc2pπ− decay is also found. Using the $$ {\Lambda}_{\mathrm{b}}^0 $$ Λ b 0 → χc1pK− decay as normalisation channel, the ratios of branching fractions are measured to be$$ {\displaystyle \begin{array}{c}\frac{\mathcal{B}\left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1}{\mathrm{p}\uppi}^{-}\right)}{\mathcal{B}\left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1}{\mathrm{p}\mathrm{K}}^{-}\right)}=\left(6.59\pm 1.01\pm 0.22\right)\times {10}^{-2},\\ {}\frac{\mathcal{B}\left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}2}{\mathrm{p}\uppi}^{-}\right)}{\mathcal{B}\left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1}{\mathrm{p}\uppi}^{-}\right)}=0.95\pm 0.30\pm 0.04\pm 0.04,\\ {}\frac{\mathcal{B}\left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}2}{\mathrm{p}\mathrm{K}}^{-}\right)}{\mathcal{B}\left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1}{\mathrm{p}\mathrm{K}}^{-}\right)}=1.06\pm 0.05\pm 0.04\pm 0.04,\end{array}} $$ B Λ b 0 → χ c 1 pπ − B Λ b 0 → χ c 1 pK − = 6.59 ± 1.01 ± 0.22 × 10 − 2 , B Λ b 0 → χ c 2 pπ − B Λ b 0 → χ c 1 pπ − = 0.95 ± 0.30 ± 0.04 ± 0.04 , B Λ b 0 → χ c 2 pK − B Λ b 0 → χ c 1 pK − = 1.06 ± 0.05 ± 0.04 ± 0.04 , where the first uncertainty is statistical, the second is systematic and the third is due to the uncertainties in the branching fractions of χc1,2→ J/ψγ decays.

scholarly journals Measurement of $$K_S^0$$ and $$\Lambda ^0$$ production in $$t \bar{t}$$ dileptonic events in pp collisions at $$\sqrt{s} =$$ 7 TeV with the ATLAS detector

2019 ◽  
Vol 79 (12) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
O. Abdinov ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Final States ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Proton Proton ◽  
Proton Collisions ◽  
Strange Particles ◽  
Proton Proton Collisions

AbstractMeasurements of $$K_S^0$$KS0 and $$\Lambda ^0$$Λ0 production in $$t\bar{t}$$tt¯ final states have been performed. They are based on a data sample with integrated luminosity of 4.6 $$\mathrm {fb}^{-1}$$fb-1 from proton–proton collisions at a centre-of-mass energy of 7 TeV, collected in 2011 with the ATLAS detector at the Large Hadron Collider. Neutral strange particles are separated into three classes, depending on whether they are contained in a jet, with or without a b-tag, or not associated with a selected jet. The aim is to look for differences in their main kinematic distributions. A comparison of data with several Monte Carlo simulations using different hadronisation and fragmentation schemes, colour reconnection models and different tunes for the underlying event has been made. The production of neutral strange particles in $$t\bar{t}$$tt¯ dileptonic events is found to be well described by current Monte Carlo models for $$K_S^0$$KS0 and $$\Lambda ^0$$Λ0 production within jets, but not for those produced outside jets.

scholarly journals Status of searches for electroweak-scale supersymmetry after LHC Run 2

2022 ◽  
Author(s):  
Wolfgang Adam ◽  
Iacopo Vivarelli
Keyword(s):  
Hadron Collider ◽  
General Purpose ◽  
Conclusive Evidence ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Large Dataset ◽  
Proton Proton ◽  
Proton Collisions ◽  
Proton Proton Collisions ◽  
Second Period

The second period of datataking at the Large Hadron Collider (LHC) has provided a large dataset of proton–proton collisions that is unprecedented in terms of its centre-of-mass energy of 13 TeV and integrated luminosity of almost 140 fb[Formula: see text]. These data constitute a formidable laboratory for the search for new particles predicted by models of supersymmetry. The analysis activity is still ongoing, but a host of results on supersymmetry had already been released by the general purpose LHC experiments ATLAS and CMS. In this paper, we provide a map into this remarkable body of research, which spans a multitude of experimental signatures and phenomenological scenarios. In the absence of conclusive evidence for the production of supersymmetric particles we discuss the constraints obtained in the context of various models. We finish with a short outlook on the new opportunities for the next runs that will be provided by the upgrade of detectors and accelerator.

scholarly journals Measurement of the transverse momentum distribution of Drell–Yan lepton pairs in proton–proton collisions at $$\sqrt{s}=13\,$$TeV with the ATLAS detector

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Angular Variable ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Lepton Pairs ◽  
Muon Pair ◽  
Full Spectrum ◽  
Proton Proton ◽  
Proton Collisions ◽  
Proton Proton Collisions

Abstract This paper describes precision measurements of the transverse momentum $$p_\mathrm {T}^{\ell \ell }$$pTℓℓ ($$\ell =e,\mu $$ℓ=e,μ) and of the angular variable $$\phi ^{*}_{\eta }$$ϕη∗ distributions of Drell–Yan lepton pairs in a mass range of 66–116 GeV. The analysis uses data from 36.1 fb$$^{-1}$$-1 of proton–proton collisions at a centre-of-mass energy of $$\sqrt{s}=13\,$$s=13TeV collected by the ATLAS experiment at the LHC in 2015 and 2016. Measurements in electron-pair and muon-pair final states are performed in the same fiducial volumes, corrected for detector effects, and combined. Compared to previous measurements in proton–proton collisions at $$\sqrt{s}=7$$s=7 and $$8\,$$8TeV, these new measurements probe perturbative QCD at a higher centre-of-mass energy with a different composition of initial states. They reach a precision of 0.2$$\%$$% for the normalized spectra at low values of $$p_\mathrm {T}^{\ell \ell }$$pTℓℓ. The data are compared with different QCD predictions, where it is found that predictions based on resummation approaches can describe the full spectrum within uncertainties.

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