نتایج جستجو برای: charm bond
تعداد نتایج: 75189 فیلتر نتایج به سال:
Because of their large masses, one expects charm mesons to be mostly produced in the initial preequilibrium stage of relativistic heavy ion collisions. They have thus been suggested as possible probes of the initial dynamics in these collisions. Previous studies have been concentrated on the production of charm quarks from the preequilibrium partonic matter [1]. For charm meson production from ...
We address the nonperturbative effects associated with soft charm quarks in inclusive B decays. Such corrections are allowed by the OPE, but have largely escaped attention so far. The related four-quark ‘double heavy’ expectation values of the form 〈B|b̄c c̄b|B〉 are computed in the 1/mc expansion by integrating out the charm field to one and two loops. A significant enhancement of the two-loop co...
Charm quarks are produced copiously in deep inelastic scattering (DIS) at HERA. At sufficiently high photon virtualities, Q, the production of charm quarks constitutes up to 30% of the total cross section [1,2]. Previous measurements of D∗ cross sections [1,2,3,4] indicate that the production of charm quarks in DIS in the range 1 < Q < 600 GeV is consistent with QCD calculations in which charm ...
The ALICE experiment is devoted to the study of heavy-ion collisions at the CERN LHC collider. We present the results of a feasibility study for the detection of D → Kπ decays in Pb–Pb collisions with ALICE. 1 Physics motivation The aim of the ALICE [1] experiment is to study the behaviour of nuclear matter in the conditions of high densities and temperatures in which a transition to a deconfin...
Charm physics plays a unique dual role in the modern investigations of flavor physics. Charm decay and production experiments provide valuable checks and supporting measurements for studies of CP-violation in measurements of CKM parameters in b-physics, as well as outstanding opportunities for searches for new physics. Historically, many methods of heavy quark physics have been first tested in ...
In dynamic force spectroscopy, a (bio-)molecular complex is subjected to a steadily increasing force until the chemical bond breaks. Repeating the same experiment many times results in a broad distribution of rupture forces, whose quantitative interpretation represents a formidable theoretical challenge. In this study we address the situation that more than a single molecular bond is involved i...
Almost since the discovery of charm mesons, mixing of D −D 0 mesons have been sought in analogy to the well-known K−K 0 mixing. Due to very effective GIM suppression, the expected mixing rate in the charm system is much smaller than for kaons. Only very recently, the BaBar [1] and Belle [2] collaborations have reported the first evidence of charm mixing. These results have renewed the interest ...
We report measurements of the charm-anticharm production asymmetries for Λc , Σ c , Σ 0 c , Σ ++∗ c , Σ 0∗ c , and Λ + c (2625) baryons from the Fermilab photoproduction experiment FOCUS (E831). These asymmetries are integrated over the region where the spectrometer has good acceptance. In addition, we have obtained results for the photoproduction asymmetries of the Λc baryons as functions of p...
Some recent ZEUS results on the photoproduction of open charm and possible implications for photon structure are discussed. 1 Open Charm Photoproduction at HERA Photoproduction of ‘open’ charm (as opposed to cc̄ bound states) can take place via several processes at HERA. The most obvious is photon-gluon fusion. The photon interacts directly with a gluon from the proton via t-channel charm quark,...
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