scholarly journals Review of recent forward physics results from the CMS experiment

2019 ◽  
Vol 208 ◽  
pp. 05002
Author(s):  
Ralf Ulrich
Keyword(s):  
Cross Sections ◽  
Cosmic Ray ◽  
High Energy ◽  
Forward Physics ◽  
Final State ◽  
Double Parton Scattering ◽  
Cosmic Ray Interactions ◽  
Wide Range ◽  
Very High Energy ◽  
Parton Scattering

There is a rich program of forward physics measurements within the CMS Collaboration covering a wide range of topics. In many cases there is a connection to quantities and effects relevant for very high energy cosmic ray interactions. Some of the recent measurements in the fields of exclusive final states, low-pT inclusive and diffractive cross sections, underlying event, multiparton interactions, double parton scattering, final state particle correlations and minimum bias results are briefly summarized here.

scholarly journals Production of quarkonium pairs in high-energy proton-proton collisions

2019 ◽  
Vol 199 ◽  
pp. 01021 ◽  
Author(s):  
Wolfgang Schäfer
Keyword(s):  
Pair Production ◽  
Cross Sections ◽  
High Energy ◽  
Open Problems ◽  
Proton Proton ◽  
Proton Collisions ◽  
Double Parton Scattering ◽  
Parton Scattering ◽  
To Receive ◽  
Proton Proton Collisions

Recently there has been much interest in the pair production of quarkonia (charmonia, bottomonia). There are two main motivations behind these studies: first, these processes may help to differentiate between different proposed production mechanisms via color-octet and color-singlet QQ̄ -pair production. Second, the production of quarkonium pairs is expected to receive an important contribution from double parton scattering (DPS) processes. There remain a number of open problems, especially with the CMS and ATLAS data. In the kinematics of these experiments, the leading order of $O\left( {\alpha _S^4} \right)$ is clearly not sufficient. The double parton scattering (DPS) contribution was claimed to be large or even dominant in some corners of the phase space, when the rapidity distance Δy between two J/ψ mesons is large. However the effective cross sections σeff found from empirical analyses are about a factor 2.5 smaller than the usually accepted σeff = 15 mb. Here we discuss, which single-parton-scattering mechanisms can mimic the behavior of DPS induced production. Here especially the production of χ-pairs is important.

scholarly journals Opening Remarks ~ Prospects of very high energy cosmic ray interactions for astroparticle physics

2019 ◽  
Vol 208 ◽  
pp. 01001
Author(s):  
Yoshitaka Itow
Keyword(s):  
Cosmic Rays ◽  
Particle Production ◽  
Cosmic Ray ◽  
High Energy ◽  
Hadronic Interactions ◽  
High Energy Cosmic Rays ◽  
Cosmic Ray Interactions ◽  
Precise Knowledge ◽  
Very High Energy ◽  
Very High

Hadronic interactions of very high energy cosmic rays have been studied in various aspects of motivation. In recent decades, mainly motivated by air shower experiments, modelling of very high energy cosmic ray interactions have been greatly improved together with new data obtained from high energy colliders such as the LHC. Regarding recent rapid progress of multi-messenger astronomy, a precise knowledge on secondary particle production by cosmic rays at very high energy is largely indispensable. This would give us a new insight and new motivation to study minimum bias hadronic interactions of very high energy cosmic rays.

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