38 research outputs found
Conventional versus single-ladder-splitting contributions to double parton scattering production of two quarkonia, two Higgs bosons and
The double parton distributions (dPDF), both conventional and those
corresponding to parton splitting, are calculated and compared for different
two-parton combinations. The conventional and splitting dPDFs have very similar
shape in and . We make a first quantitative evaluation of the
single-ladder-splitting contribution to double parton scattering (DPS)
production of two S- or P-wave quarkonia, two Higgs bosons and . The ratio of the single-ladder-splitting to conventional contributions is
discussed as a function of centre-of-mass energy, mass of the produced system
and other kinematical variables. Using a simple model for the dependence of the
conventional two-parton distribution on transverse parton separation (Gaussian
and independent of and scales), we find that the 2v1 contribution is as
big as the 2v2 contribution discussed in recent years in the literature. This
means that the phenomenological analyses of including only the
conventional DPS mechanism have to be revised including explicitly the
single-ladder-splitting contributions discussed here. The differential
distributions in rapidity and transverse momenta calculated for conventional
and single-ladder-splitting DPS processes are however very similar which causes
their experimental separation to be rather difficult, if not impossible. The
direct consequence of the existence of the two components (conventional and
splitting) is the energy and process dependence of the empirical parameter
. This is illustrated in our paper for the considered processes.Comment: 20 pages, 11 figures, 3 table
Open charm meson production at LHC
We discuss charm production at the LHC. The production of single
pairs is calculated in the -factorization approach. We use
Kimber-Martin-Ryskin unintegrated gluon distributions in the proton. The
hadronization is included with the help of Peterson fragmentation functions.
Transverse momentum and pseudorapidity distributions of charmed mesons are
presented and compared to recent results of the ALICE, LHCb and ATLAS
collaborations. Furthermore we discuss production of two pairs of
within a simple formalism of double-parton scattering (DPS). Surprisingly large
cross sections, comparable to single-parton scattering (SPS), are predicted for
LHC energies. We discuss perspectives how to identify the double scattering
contribution. We predict much larger cross section for large rapidity distance
between charm quarks from different hard parton scatterings compared to single
scattering.Comment: 5 pages, 4 figures, talk given by R. Maciula at the MESON2012 - 12th
International Workshop on Meson Production, Properties and Interaction, 31
May - 5 June 2012, Krakow, Polan
Measurement of charm production at central rapidity in proton-proton collisions at TeV
The -differential production cross sections of the prompt (B
feed-down subtracted) charmed mesons D, D, and D in the rapidity
range , and for transverse momentum GeV/, were
measured in proton-proton collisions at TeV with the ALICE
detector at the Large Hadron Collider. The analysis exploited the hadronic
decays DK, DK, DD, and their charge conjugates, and was performed on a
nb event sample collected in 2011 with a
minimum-bias trigger. The total charm production cross section at TeV and at 7 TeV was evaluated by extrapolating to the full phase space
the -differential production cross sections at TeV
and our previous measurements at TeV. The results were compared
to existing measurements and to perturbative-QCD calculations. The fraction of
cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/307
The Forward Physics Facility: Sites, Experiments, and Physics Potential
The Forward Physics Facility (FPF) is a proposal to create a cavern with thespace and infrastructure to support a suite of far-forward experiments at theLarge Hadron Collider during the High Luminosity era. Located along the beamcollision axis and shielded from the interaction point by at least 100 m ofconcrete and rock, the FPF will house experiments that will detect particlesoutside the acceptance of the existing large LHC experiments and will observerare and exotic processes in an extremely low-background environment. In thiswork, we summarize the current status of plans for the FPF, including recentprogress in civil engineering in identifying promising sites for the FPF andthe experiments currently envisioned to realize the FPF's physics potential. Wethen review the many Standard Model and new physics topics that will beadvanced by the FPF, including searches for long-lived particles, probes ofdark matter and dark sectors, high-statistics studies of TeV neutrinos of allthree flavors, aspects of perturbative and non-perturbative QCD, andhigh-energy astroparticle physics.<br
The Forward Physics Facility at the High-Luminosity LHC
High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential