Search results for "nuclear physics"
showing 10 items of 5307 documents
Measurements of the charged particle multiplicity distribution in restricted rapidity intervals
1995
Charged particle multiplicity distributions have been measured with the ALFPH detector in restricted rapidity intervals \Y\ less than or equal to 0.5, 1.0, 1.5, 2.0 along the thrust axis and also without restriction on rapidity. The distribution for the full range can be parametrized by a log-normal distribution. For smaller windows one finds a more complicated structure, which is understood to arise from perturbative effects. The negative-binomial distribution fails to describe the data both with and without the restriction on rapidity. The JETSET model is found to describe all aspects of the data while the width predicted by HERWIG is in significant disagreement.
Exclusive ω meson production at COMPASS
2016
Exclusive ω meson production is studied by the COMPASS Collaboration using the CERN 160 GeV/ c muon beam and a transversely polarised proton target. Single-spin and double-spin asymmetries are measured, some of which are sensitive to the Generalised Parton Distributions E that are related to quark orbital angular momenta. The results, which are sensitive also to the pion-pole contribution to the production mechanism, are compared to the predictions of a phenomenological model.
On heavy baryon decay form factors
1991
We consider in detail the consequences of the heavy quark mass limit in the weak decay of 1/2+ heavy baryons to 1/2+ and 3/2+ heavy baryon final states. We also analyze heavy baryon to light baryon transitions as well ase+e−-annihilation into heavy baryon-antibaryonpairs. We discuss possible approximations to the most general approach and some of their implications for future experiments.
Measurement of the Effective Weak Mixing Angle inpp¯→Z/γ*→e+e−Events
2015
We present a measurement of the fundamental parameter of the standard model, the weak mixing angle, in $p\bar{p}\rightarrow Z/\gamma^{*}\rightarrow e^{+}e^{-}$ events at a center of mass energy of 1.96 TeV, using data corresponding to 9.7 fb$^{-1}$ of integrated luminosity collected by the D0 detector at the Fermilab Tevatron. The effective weak mixing angle is extracted from the forward-backward charge asymmetry as a function of the invariant mass around the Z boson pole. The measured value of $\sin^2\theta_{\text{eff}}^{\text{$\ell$}}=0.23146 \pm 0.00047$ is the most precise measurement from light quark interactions to date, with a precision close to the best LEP and SLD results.
Studies of Λcproduction in pp and p-Pb collisions 1 with ALICE at 2 the LHC
2017
A Large Ion Collider Experiment (ALICE) was designed to study the strongly interacting medium created in heavy-ion collisions at LHC energies, the Quark Gluon Plasma (QGP). Heavy quarks (charm and beauty), produced in the early stages of the collisions, are among the most powerful probes to study this state of matter. To study the QGP effects, it is important to establish reference data, which is done by analysing results from pp and p-Pb collisions.We report on the charmed baryon Λc measurement in pp collisions at √s = 7 TeV and in p-Pb collisions at √sNN = 5.02 TeV with the ALICE experiment, through the reconstruction of the decay channels Λc + → p K S 0 and Λc + → pK − π + .
Colloquium: New physics search with flavor in the LHC era
2013
We give a status report on quark flavour physics in view of the latest data from the B factories and the LHC, and discuss the impact of the latest experimental results on new physics in the MFV framework. We also show some examples of the implications in supersymmetry. A status report on quark flavor physics in view of the latest data from the B factories and the LHC is given, and the impact of the latest experimental results on new physics in the minimal flavor violation framework is discussed. Also shown are some examples of the implications in supersymmetry. We give a status report on quark flavour physics in view of the latest data from the B factories and the LHC, and discuss the impac…
Direct Bounds on Heavy Top-Like Quarks With Standard and Exotic Decays
2017
Heavy vector-like quarks with electric charge $Q=2/3$ (also called \textit{heavy tops}) appear naturally in many extensions of the Standard Model. Although these typically predict the existence of further particles below the TeV scale, direct searches for heavy tops have been performed assuming that they decay only into SM particles. The aim of this paper is to overcome this situation. We consider the most constraining experimental LHC searches for vector-like quarks, including analyses of the 36 fb$^{-1}$ of data collected in the latest run at 13 TeV of center of mass energy, as well as searches sensitive to heavy tops decaying into a new scalar, $S$. Combining all these, we derive bounds …
Exotic hyperons: Theoretical status and search perspectives in hyperon beam facilities
1992
The theoretical models that predict the existence of exotic hyperons made of more than three quarks are reviewed. We present the properties of exotic hyperons with strangenessS=−1 (quark contents $$sqqq\bar q$$ ),S=−2 ( $$ssqq\bar q$$ ) andS=−3 ( $$sssq\bar q$$ ) predicted by the sum rules for reggeon-particle scattering amplitudes. The inclusive cross sections for the production of these hyperons in hyperon-proton interactions are calculated. The cross sections turn out to be of the order of millibarns, thus opening a good perspective to encounter such exotic hyperons in the available hyperon beam facilities at CERN and FNAL. We also propose to study the Regge trajectories corresponding to…
Measurement of Spin Correlation in Top-Antitop Quark Events and Search for Top Squark Pair Production inppCollisions ats=8 TeVUsing the ATLAS Detect…
2015
A measurement of spin correlation in t (t) over bar production is presented using data collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass ...
Search for a Heavy Toplike Quark inpp¯Collisions ats=1.96 TeV
2011
We present the results of a search for pair production of a heavy toplike (t') quark decaying to Wq final states using data corresponding to an integrated luminosity of 5.6 fb(-1) collected by the CDF II detector in pp collisions at √s=1.96 TeV. We perform parallel searches for t'→Wb and t'→Wq (where q is a generic down-type quark) in events containing a lepton and four or more jets. By performing a fit to the two-dimensional distribution of total transverse energy versus reconstructed t' quark mass, we set upper limits on the t't' production cross section and exclude a standard model fourth-generation t' quark decaying to Wb (Wq) with mass below 358 (340) GeV/c(2) at 95% C.L.