scholarly journals Precise determination of the $$B_{\mathrm{s}}^0$$–$$\overline B_{\mathrm{s}}^0$$ oscillation frequency

2022 ◽  
Author(s):  
◽  
R. Aaij ◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Oscillation Frequency ◽  
Strange Quark ◽  
Mass Difference ◽  
Hadron Collider ◽  
Precise Determination ◽  
Proton Proton ◽  
Proton Collisions ◽  
Lhcb Detector ◽  
Proton Proton Collisions

AbstractMesons comprising a beauty quark and strange quark can oscillate between particle ($${B}_{\mathrm{s}}^{0}$$ B s 0 ) and antiparticle ($${\overline{B}}_{\mathrm{s}}^{0}$$ B ¯ s 0 ) flavour eigenstates, with a frequency given by the mass difference between heavy and light mass eigenstates, Δms. Here we present a measurement of Δms using $${B}_{\mathrm{s}}^{0}\to {D}_{\mathrm{s}}^{-}$$ B s 0 → D s − π+ decays produced in proton–proton collisions collected with the LHCb detector at the Large Hadron Collider. The oscillation frequency is found to be Δms = 17.7683 ± 0.0051 ± 0.0032 ps−1, where the first uncertainty is statistical and the second is systematic. This measurement improves on the current Δms precision by a factor of two. We combine this result with previous LHCb measurements to determine Δms = 17.7656 ± 0.0057 ps−1, which is the legacy measurement of the original LHCb detector.

scholarly journals On the precise determination of the Tsallis parameters in proton–proton collisions at LHC energies

2018 ◽  
Vol 45 (5) ◽  
pp. 055001 ◽  
Author(s):  
T Bhattacharyya ◽  
J Cleymans ◽  
L Marques ◽  
S Mogliacci ◽  
M W Paradza
Keyword(s):  
Precise Determination ◽  
Proton Proton ◽  
Proton Collisions ◽  
Proton Proton Collisions

scholarly journals Back-to-Back Isolated Photon-Quarkonium Production at the LHC and the Transverse-Momentum-Dependent Distributions of the Gluons in the Proton

2016 ◽  
Vol 40 ◽  
pp. 1660015 ◽  
Author(s):  
J. P. Lansberg
Keyword(s):  
Transverse Momentum ◽  
Experimental Determination ◽  
Heavy Quarkonia ◽  
Proton Proton ◽  
Transverse Momentum Dependent ◽  
Proton Collisions ◽  
Quarkonium Production ◽  
Linearly Polarized ◽  
Proton Proton Collisions

The study of isolated heavy quarkonia, such as [Formula: see text] and [Formula: see text], produced in association with a photon in proton-proton collisions at the LHC, is probably the optimal way to get right away a first experimental determination of two gluon transverse-momentum-dependent distribution (TMDs) in an unpolarized proton, [Formula: see text] and [Formula: see text], the latter giving the distribution of linearly polarized gluons. To substantiante this, we calculate the transverse-momentum-dependent effects that arise in the process under study and discuss the feasibility of their measurements.

Models prediction of hadrons production ratios in pp collisions at s = 7 TeV

2019 ◽  
Vol 34 (13) ◽  
pp. 1950090 ◽  
Author(s):  
M. Ajaz ◽  
M. Bilal ◽  
Y. Ali ◽  
M. K. Suleymanov ◽  
K. H. Khan
Keyword(s):  
Experimental Data ◽  
Transverse Momentum ◽  
Charged Particles ◽  
Hadron Production ◽  
Proton Proton ◽  
Proton Collisions ◽  
Particle Ratios ◽  
Production Models ◽  
Lhcb Detector ◽  
Proton Proton Collisions

The pseudorapidity [Formula: see text] dependence of charged-particles ratios in three transverse momentum [Formula: see text] regions, obtained by hadron production models, in proton–proton collisions at 7 TeV are compared with the measurements of LHCb detector. Compared to the experimental data, the [Formula: see text] ratios are independent of [Formula: see text] and [Formula: see text] and are very well predicted by all models (DPMJETIII, EPOS1.99, EPOS-LHC, HIJING1.383, QGSJETII-04 and Sibyll2.3c). All models predict the [Formula: see text] ratio at low [Formula: see text] for [Formula: see text], but underestimate afterward while reproducing the experimental data at medium and high [Formula: see text] very well. The [Formula: see text] ratio is described by the models very well at high [Formula: see text] in the low and medium [Formula: see text] region. At high [Formula: see text], models predict the experimental data well, except Sibyll2.3c that slightly overestimates. The [Formula: see text] ratio is predicted by EPOS1.99, HIJING and Sibyll at low [Formula: see text] and EPOS-LHC, EPOS1.99 and Sibyll predicted at high [Formula: see text] for low [Formula: see text]. For medium [Formula: see text], EPOS1.99 and Sibyll predict very well for [Formula: see text] while EPOS-LHC and HIJING models reproduce the data for [Formula: see text]. All models underpredict the [Formula: see text] ratio for [Formula: see text]. For the [Formula: see text] and [Formula: see text] ratios, only Sibyll and EPOS1.99 models could reproduce some regions of [Formula: see text] and [Formula: see text]. None of the models satisfactorily predict all the ratios. the same particle ratios are well described by most of the models while the discrepancies occur mostly in predicting the different particles ratios.

scholarly journals Timepix3 Luminosity Determination of 13 TeV Proton-Proton Collisions at the ATLAS Experiment

2020 ◽  
Vol 225 ◽  
pp. 01002
Author(s):  
Andreé Sopczak
Keyword(s):  
Simple Model ◽  
Number Of Clusters ◽  
Proton Proton ◽  
Proton Collisions ◽  
Atlas Experiment ◽  
Long Term Stability ◽  
Counting Methods ◽  
Proton Proton Collisions

Medipix and Timepix devices, installed in the ATLAS cavern at the LHC, have provided valuable complementary luminosity information. Results are presented from measurements with Timepix3 (TPX3) detectors. In contrast with previously employed frame-based data acquisition, the TPX3 detector remains active continuously, sending information on pixel hits as they occur. Hit- and cluster-counting methods were used for the luminosity determination of the LHC protonproton collisions. The LHC luminosity versus time is determined using these two methods and fitted to a simple model, which incorporates luminosity reduction from single bunch and beam-beam interactions. The precision of the luminosity determination could be improved by counting the number of clusters, instead of just pixel hits. The internal precision and long-term stability of the TPX3 luminosity measurement are below 0.5%. TPX3, owing to its 1.56 ns time-tagging, is able to resolve the time structure of the luminosity due to the collisions of individual proton bunches when integrated over an LHC fill.

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 Luminosity Measurements at the LHC at CERN Using Medipix, Timepix and Timepix3 Devices

Physics ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 579-654
Author(s):  
André Sopczak
Keyword(s):  
Hadron Collider ◽  
Precise Determination ◽  
Particle Accelerator ◽  
Proton Proton ◽  
Performance Improvements ◽  
Long Term Stability ◽  
Pixel Detectors ◽  
Relative Luminosity ◽  
Radiation Induced

The precise determination of the luminosity is essential for many analyses in physics based on the data from the particle accelerator Large Hadron Collider (LHC) at CERN. There are different types of detectors used for the luminosity measurements. The focus of this review is on luminosity measurements with hybrid-pixel detectors and the progress made over the past decade. The first generations of detectors of the Medipix and Timepix families had frame-based readout, while Timepix3 has a quasi-continuous readout. The applications of the detectors are manifold, and in particular, the detectors have been operated in the harsh environment of the LHC. The excellent performance in detecting high fluxes of elementary particles made these detectors ideal tools to measure the delivered luminosity resulting from proton–proton collisions. Important aspects of this review are the performance improvements in relative luminosity measurements from one detector generation to another, the long-term stability of the measurements, absolute luminosity measurements, material activation (radiation-induced) corrections, and the measurement of luminosity from neutron counting. Rather than bunch-average luminosity provided by previous detector generations, owing to the excellent time-resolution, Timepix3 measured the luminosity of individual proton bunches that are 25 ns apart. This review demonstrates the large progress in the precision of luminosity measurements during LHC Run-1 and Run-2 operations using hybrid-pixel detectors, and thus their importance for luminosity measurements in the future of LHC operations.

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