947 research outputs found
Predictions with Lattice QCD
In recent years, we used lattice QCD to calculate some quantities that were
unknown or poorly known. They are the dependence of the form factor in
semileptonic decay, the leptonic decay constants of the and
mesons, and the mass of the meson. In this paper, we summarize
these calculations, with emphasis on their (subsequent) confirmation by
measurements in , and collisions.Comment: 5 pages; update of hep-lat/0509169, with experimental confirmation of
form factors from Belle and fDs from BaBar; presented at SciDAC 2006 for the
Fermilab Lattice, MILC, and HPQCD Collaboration
Probing Yukawa Unification with K and B Mixing
We consider corrections to the unification of down-quark and charged-lepton
Yukawa couplings in supersymmetric GUTs, which links the large nu_tau-nu_mu
mixing angle to b -> s transitions. These corrections generically occur in
simple grand-unified models with small Higgs representations and affect s -> d
and b -> d transitions via the mixing of the corresponding right-handed
superpartners. On the basis of a specific SUSY-SO(10) model, we analyze the
constraints from K-Kbar and B-Bbar mixing on the additional
\tilde{d}_R-\tilde{s}_R rotation angle theta. We find that epsilon_K already
sets a stringent bound on theta, theta^{max}=O(1 degree), indicating a very
specific flavor structure of the correction operators. The impact of the large
neutrino mixings on the unitarity triangle analysis is also briefly discussed,
as well as their ability to account for the sizeable CP-violating phase
observed recently in B_s -> psi phi decays.Comment: 19 pages. Discussion in Sec. 5.2 slightly extended; minor numerical
modifications in Secs. 5.1 to 5.4, conclusions unchanged. Version to appear
in JHE
Study of high temperature and high density plasmoids in axially symmetrical magnetic fields
Within the framework of an Institutional Partnership of the Alexander von Humboldt Foundation, the Budker Institute of Nuclear Physics Novisibirsk (BINP) and Forschungszentrum Dresden-Rossendorf worked together in a joint project devoted to the research at the coupled GDT-SHIP facility of the BINP with the focus on the study of plasma phenomena within the SHIP mirror section. The project began at July 1st, 2005 and ended on August 30th, 2008. It included work packages of significant theoretical, computational and analyzing investigations. The focus of this final report is on the presentation of results achieved whereas the work that was done is described briefly only. Chapter 2 illustrates the GDT-SHIP facility and describes shortly the planned topics of the SHIP plasma research. Chapter 3 explains the main extensions and modifications of the Integrated Transport Code System (ITCS) which were necessary for the calculations of the fast ion and neutral gas particle fields in SHIP, describes briefly the scheme of computations and presents significant results of pre-calculations from which conclusions were drawn regarding the experimental program of SHIP. In chapter 4, the theoretical and computational investigations of self-organizing processes in two-component plasmas of the GDT-SHIP device are explained and the results hitherto achieved are presented. In chapter 5, significant results of several experiments with moderate and with enhanced plasma parameters are presented and compared with computational results obtained with the ITCS. Preparing neutron measurements which are planned for neutron producing experiments with deuterium injection, Monte Carlo neutron transport calculations with the MCNP code were also carried out. The results are presented. Finally, from the results obtained within the joint research project important conclusions are drawn in chapter 6
The CKM Matrix and The Unitarity Triangle: Another Look
The unitarity triangle can be determined by means of two measurements of its
sides or angles. Assuming the same relative errors on the angles
and the sides , we find that the pairs
and are most efficient in determining
that describe the apex of the unitarity triangle. They
are followed by , , ,
and . As the set \vus, \vcb, and appears to be
the best candidate for the fundamental set of flavour violating parameters in
the coming years, we show various constraints on the CKM matrix in the
plane. Using the best available input we determine the universal
unitarity triangle for models with minimal flavour violation (MFV) and compare
it with the one in the Standard Model. We present allowed ranges for , , , , and within the
Standard Model and MFV models. We also update the allowed range for the
function that parametrizes various MFV-models.Comment: "published version. few typos corrected, results unchanged
B Physics at the Tevatron: Run II and Beyond
This report provides a comprehensive overview of the prospects for B physics
at the Tevatron. The work was carried out during a series of workshops starting
in September 1999. There were four working groups: 1) CP Violation, 2) Rare and
Semileptonic Decays, 3) Mixing and Lifetimes, 4) Production, Fragmentation and
Spectroscopy. The report also includes introductory chapters on theoretical and
experimental tools emphasizing aspects of B physics specific to hadron
colliders, as well as overviews of the CDF, D0, and BTeV detectors, and a
Summary.Comment: 583 pages. Further information on the workshops, including
transparencies, can be found at the workshop's homepage:
http://www-theory.lbl.gov/Brun2/. The report is also available in 2-up
http://www-theory.lbl.gov/Brun2/report/report2.ps.gz or chapter-by-chapter
http://www-theory.lbl.gov/Brun2/report
Experimental study of direct photon emission in K- --> pi- pi0 gamma decay using ISTRA+ detector
The branching ratio in the charged-pion kinetic energy region of 55 to 90 MeV
for the direct photon emission in the K- --> pi- pi0 gamma decay has been
measured using in-flight decays detected with the ISTRA+ setup operating in the
25 GeV/c negative secondary beam of the U-70 PS. The value
Br(DE)=[0.37+-0.39(stat)+-0.10(syst)]*10^(-5) obtained from the analysis of 930
completely reconstructed events is consistent with the average value of two
stopped-kaon experiments, but it differs by 2.5 standard deviations from the
average value of three in-flight-kaon experiments. The result is also compared
with recent theoretical predictions.Comment: 13 pages, 8 figure
Gold-plated Mode of CP-Violation in Decays of B_c Meson from QCD Sum Rules
The model-independent method based on the triangle ideology is implemented to
extract the CKM-matrix angle gamma in the decays of doubly heavy long-lived
meson B_c. We analyze a color structure of diagrams and conditions to
reconstruct two reference-triangles by tagging the flavor and CP eigenstates of
D^0 meson in the fixed exclusive channels. The characteristic branching ratios
are evaluated in the framework of QCD sum rules.Comment: 11 pages, RevTeX4 file, 4 eps-figure
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Observation of Exclusive Electron-Positron Production in Hadron-Hadron Collisions
We present the first observation of exclusive e{sup +}e{sup -} production in hadron-hadron collisions, using p{bar p} collision data at {radical}s = 1.96 TeV taken by the Run II Collider Detector at Fermilab, and corresponding to an integrated luminosity of 532 pb{sup -1}. We require the absence of any particle signatures in the detector except for an electron and a positron candidate, each with transverse energy E{sub T} > 5 GeV and pseudorapidity |{eta}| < 2. With these criteria, 16 events are observed compared to a background expectation of 1.9 {+-} 0.3 events. These events are consistent in cross section and properties with the QED process p{bar p} {yields} p + e{sup +}e{sup -} + {bar p} through two-photon exchange. The measured cross section is 1.6{sub -0.3}{sup +0.5}(stat) {+-} 0.3(syst) pb. This agrees with the theoretical prediction of 1.71 {+-} 0.01 pb
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