Search results for "Quark"
showing 10 items of 2905 documents
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.
Search for techniparticles in e +jets events at D0
2006
We search for the technicolor process ppbar -> rho_T/omega_T ->W+pi_T in events containing one electron and two jets, in data corresponding to an integrated luminosity of 390 pb-1, recorded by the D0 experiment at the Fermilab Tevatron. Technicolor predicts that technipions, pi_T, decay dominantly into b-bbar, b-cbar, or bbar-c, depending on their charge. In these events b and c quarks are identified by their secondary decay vertices within jets. Two analysis methods based on topological variables are presented. Since no excess above the standard model prediction was found, the result is presented as an exclusion in the pi_T vs. rho_T mass plane for a given set of model parameters.
Search for heavy resonances with the ATLAS detector
2014
The ATLAS detector at the Large Hadron Collider (LHC) is used to search for heavy resonances in various final states. Recent results from different analyses of the proton-proton (pp) collisions recorded in 2012 at a center-of-mass energy of √s =8 TeV corresponding to an integrated luminosity of Lint ≈ 20 fb−1 are presented. Various models are considered such as W′ and Z′ bosons, chiral bosons, excited quarks and technicolor, as well as a Randall-Sundrum graviton, the ADD large extra dimension scenario, (quantum) black holes and contact interactions.
Doubly charmed Ξcc molecular states from meson-baryon interaction
2018
Stimulated by the new experimental LHCb findings associated with the ${\mathrm{\ensuremath{\Omega}}}_{c}$ states, some of which we have described in a previous work as being dynamically generated through meson-baryon interaction, we have extended this approach to make predictions for new ${\mathrm{\ensuremath{\Xi}}}_{cc}$ molecular states in the $C=2$, $S=0$, and $I=1/2$ sector. These states manifest themselves as poles in the solution of the Bethe-Salpeter equation in coupled channels. The kernels of this equation were obtained using general Lagrangians coming from the hidden local gauge symmetry or massive Yang-Mills theory, and the interactions are dominated by the exchange of light vect…
Search for Maximal Flavor Violating Scalars in Same-Charge Lepton Pairs inpp¯Collisions ats=1.96 TeV
2009
Models of maximal flavor violation (MxFV) in elementary particle physics may contain at least one new scalar SU(2) doublet field {phi}{sub FV}=({eta}{sup 0},{eta}{sup +}) that couples the first and third generation quarks (q{sub 1}, q{sub 3}) via a Lagrangian term L{sub FV}={xi}{sub 13}{phi}{sub FV}q{sub 1}q{sub 3}. These models have a distinctive signature of same-charge top-quark pairs and evade flavor-changing limits from meson mixing measurements. Data corresponding to 2 fb{sup -1} collected by the Collider Dectector at Fermilab II detector in pp collisions at {radical}(s)=1.96 TeV are analyzed for evidence of the MxFV signature. For a neutral scalar {eta}{sup 0} with m{sub {eta}{sup 0}…
Discrete symmetries with neutral mesons
2018
Symmetries, and Symmetry Breakings, in the Laws of Physics play a crucial role in Fundamental Science. Parity and Charge Conjugation Violations prompted the consideration of Chiral Fields in the construction of the Standard Model, whereas CP-Violation needed at least three families of Quarks leading to Flavour Physics. In this Lecture I discuss the Conceptual Basis and the present experimental results for a Direct Evidence of Separate Reversal-in-Time T, CP and CPT Genuine Asymmetries in Decaying Particles like Neutral Meson Transitions, using Quantum Entanglement and the Decay as a Filtering Measurement. The eight transitions associated to the Flavour-CP eigenstate decay products of entang…