scholarly journals Forward di-jet production in p+Pb collisions in the small-x improved TMD factorization framework

2016 ◽  
Vol 2016 (12) ◽  
Author(s):  
A. van Hameren ◽  
P. Kotko ◽  
K. Kutak ◽  
C. Marquet ◽  
E. Petreska ◽  
...  
Keyword(s):  
Hadron Collider ◽  
Forward Direction ◽  
Gluon Density ◽  
Longitudinal Momentum ◽  
Proton Proton ◽  
Proton Collisions ◽  
Azimuthal Correlations ◽  
Small X ◽  
Saturation Effects ◽  
Proton Proton Collisions

Abstract We study the production of forward di-jets in proton-lead and proton-proton collisions at the Large Hadron Collider. Such configurations, with both jets produced in the forward direction, impose a dilute-dense asymmetry which allows to probe the gluon density of the lead or proton target at small longitudinal momentum fractions. Even though the jet momenta are always much bigger than the saturation scale of the target, Q s, the transverse momentum imbalance of the di-jet system may be either also much larger than Q s, or of the order Q s, implying that the small-x QCD dynamics involved is either linear or non-linear, respectively. The small-x improved TMD factorization framework deals with both situations in the same formalism. In the latter case, which corresponds to nearly back-to-back jets, we find that saturation effects induce a significant suppression of the forward di-jet azimuthal correlations in proton-lead versus proton-proton collisions.

scholarly journals HIGHLIGHTS FROM THE LHC

2013 ◽  
Vol 53 (A) ◽  
pp. 518-523
Author(s):  
Arno Straessner
Keyword(s):  
Large Hadron Collider ◽  
Standard Model ◽  
Hadron Collider ◽  
Centre Of Mass ◽  
Proton Proton ◽  
Exotic Particles ◽  
Proton Collisions ◽  
Total Luminosity ◽  
Future Data ◽  
Proton Proton Collisions

The Large Hadron Collider (LHC) and the two multi-purpose detectors, ATLAS and CMS, have been operated successfully at record centre-of-mass energies of 7 ÷ 8TeV. This paper presents the main physics results from proton–proton collisions based on a total luminosity of 2 × 5 fb<sup>−1</sup>. The most recent results from Standard Model measurements, Standard Model and MSSM Higgs searches, as well as searches for supersymmetric and exotic particles are reported. Prospects for ongoing and future data taking are presented.

scholarly journals Porting HEP Parameterized Calorimeter Simulation Code to GPUs

2021 ◽  
Vol 4 ◽  
Author(s):  
Zhihua Dong ◽  
Heather Gray ◽  
Charles Leggett ◽  
Meifeng Lin ◽  
Vincent R. Pascuzzi ◽  
...  
Keyword(s):  
Data Analysis ◽  
High Energy Physics ◽  
Hadron Collider ◽  
High Energy ◽  
Simulation Code ◽  
Proton Proton ◽  
Proton Collisions ◽  
Data Rates ◽  
The Many ◽  
Proton Proton Collisions

The High Energy Physics (HEP) experiments, such as those at the Large Hadron Collider (LHC), traditionally consume large amounts of CPU cycles for detector simulations and data analysis, but rarely use compute accelerators such as GPUs. As the LHC is upgraded to allow for higher luminosity, resulting in much higher data rates, purely relying on CPUs may not provide enough computing power to support the simulation and data analysis needs. As a proof of concept, we investigate the feasibility of porting a HEP parameterized calorimeter simulation code to GPUs. We have chosen to use FastCaloSim, the ATLAS fast parametrized calorimeter simulation. While FastCaloSim is sufficiently fast such that it does not impose a bottleneck in detector simulations overall, significant speed-ups in the processing of large samples can be achieved from GPU parallelization at both the particle (intra-event) and event levels; this is especially beneficial in conditions expected at the high-luminosity LHC, where extremely high per-event particle multiplicities will result from the many simultaneous proton-proton collisions. We report our experience with porting FastCaloSim to NVIDIA GPUs using CUDA. A preliminary Kokkos implementation of FastCaloSim for portability to other parallel architectures is also described.

scholarly journals Anomalous constants of three-boson vertices in the process of pair production of W±-bosons in proton collisions at CMS LHC

2021 ◽  
Vol 57 (1) ◽  
pp. 33-45
Author(s):  
V. V. Andreev
Keyword(s):  
Pair Production ◽  
Cross Section ◽  
Hadron Collider ◽  
W Bosons ◽  
Final States ◽  
Proton Proton ◽  
Proton Collisions ◽  
Quark Masses ◽  
Order Of Magnitude ◽  
Proton Proton Collisions

In this paper, we obtained the expected constraints on the anomalous CP-even constants of three-boson interactions on the basis of cross-section for the pair production of W+-bosons in proton-proton collisions. The constraints were obtained for luminosity and the kinematic constraints on the final states typical for the CMS experiment at the Large Hadron Collider at =13 s TeV. One-dimensional and two-dimensional regions of constraints for the anomalous parameters of three-boson interactions were calculated. When calculating the cross-section, the usual approximations of small quark masses and values of the CKM matrix elements were not used. The expected values of the anomalous constants are almost an order of magnitude less than the constraints found at the LEP collider at = 200 s GeV in the reaction e–e+ → W–W+.

scholarly journals Unveiling the strong interaction among hadrons at the LHC

Nature ◽  
2020 ◽  
Vol 588 (7837) ◽  
pp. 232-238
Author(s):  
Keyword(s):  
Strong Interaction ◽  
Nuclear Physics ◽  
Effective Interaction ◽  
Hadron Collider ◽  
Proton Proton ◽  
Proton Collisions ◽  
Strange Quarks ◽  
Short Range Part ◽  
Range Part ◽  
Proton Proton Collisions

AbstractOne of the key challenges for nuclear physics today is to understand from first principles the effective interaction between hadrons with different quark content. First successes have been achieved using techniques that solve the dynamics of quarks and gluons on discrete space-time lattices1,2. Experimentally, the dynamics of the strong interaction have been studied by scattering hadrons off each other. Such scattering experiments are difficult or impossible for unstable hadrons3–6 and so high-quality measurements exist only for hadrons containing up and down quarks7. Here we demonstrate that measuring correlations in the momentum space between hadron pairs8–12 produced in ultrarelativistic proton–proton collisions at the CERN Large Hadron Collider (LHC) provides a precise method with which to obtain the missing information on the interaction dynamics between any pair of unstable hadrons. Specifically, we discuss the case of the interaction of baryons containing strange quarks (hyperons). We demonstrate how, using precision measurements of proton–omega baryon correlations, the effect of the strong interaction for this hadron–hadron pair can be studied with precision similar to, and compared with, predictions from lattice calculations13,14. The large number of hyperons identified in proton–proton collisions at the LHC, together with accurate modelling15 of the small (approximately one femtometre) inter-particle distance and exact predictions for the correlation functions, enables a detailed determination of the short-range part of the nucleon-hyperon interaction.

scholarly journals ATLAS b-jet identification performance and efficiency measurement with $$t{\bar{t}}$$ events in pp collisions at $$\sqrt{s}=13$$ TeV

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Hadron Collider ◽  
Efficiency Measurement ◽  
Atlas Collaboration ◽  
Centre Of Mass ◽  
Identification Performance ◽  
Momentum Range ◽  
Proton Proton ◽  
Proton Collisions ◽  
Proton Proton Collisions

AbstractThe algorithms used by the ATLAS Collaboration during Run 2 of the Large Hadron Collider to identify jets containing b-hadrons are presented. The performance of the algorithms is evaluated in the simulation and the efficiency with which these algorithms identify jets containing b-hadrons is measured in collision data. The measurement uses a likelihood-based method in a sample highly enriched in $$t{\bar{t}}$$tt¯ events. The topology of the $$t \rightarrow W b$$t→Wb decays is exploited to simultaneously measure both the jet flavour composition of the sample and the efficiency in a transverse momentum range from 20 to 600 GeV. The efficiency measurement is subsequently compared with that predicted by the simulation. The data used in this measurement, corresponding to a total integrated luminosity of 80.5 $$\hbox {fb}^{-1}$$fb-1, were collected in proton–proton collisions during the years 2015–2017 at a centre-of-mass energy $$\sqrt{s}=$$s= 13 TeV. By simultaneously extracting both the efficiency and jet flavour composition, this measurement significantly improves the precision compared to previous results, with uncertainties ranging from 1 to 8% depending on the jet transverse momentum.

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