4,853 research outputs found
Next-to-leading order QCD corrections to associated production via the flavor-changing neutral-current couplings at hadron colliders
We present the complete next-to-leading order (NLO) QCD corrections to
associated production induced by the model-independent and
flavor-changing neutral-current couplings at hadron colliders, respectively.
Our results show that, for the coupling the NLO QCD corrections can
enhance the total cross sections by about 60% and 42%, and for the
coupling by about 51% and 43% at the Tevatron and LHC, respectively. The NLO
corrections, for the couplings, can enhance the total cross sections by
about 27%, and by about 42% for the coupling at the LHC. We also consider
the mixing effects between the and couplings for this process,
which can either be large or small depending on the values of the anomalous
couplings. Besides, the NLO corrections reduce the dependence of the total
cross sections on the renormalization or factorization scale significantly,
which lead to increased confidence on the theoretical predictions. And we also
evaluate the NLO corrections to several important kinematic distributions.Comment: Published version in Phys. Rev.
Cost-efficient Variable Selection Using Branching LARS
Variable selection is a difficult problem in statistical model building. Identification of cost efficient diagnostic factors is very important to health researchers, but most variable selection methods do not take into account the cost of collecting data for the predictors. The trade off between statistical significance and cost of collecting data for the statistical model is our focus. A Branching LARS (BLARS) procedure has been developed that can select and estimate the important predictors to build a model not only good at prediction but also cost efficient. BLARS method is an extension of the LARS variable selection method to incorporate various costs of factors, where branch and bound search method is employed to accelerate the search process. Both additive and non-additive costs will be addressed. The R package branchLars which implements BLARS will be described. We will show that a cheaper model could be selected by sacrificing a user selected amount of model accuracy
Determinations of form factors for semileptonic decays and leptoquark constraints
By analyzing all existing measurements for ( ) decays, we find that the determinations of both the vector
form factor and scalar form factor for semileptonic
decays from these measurements are feasible. By taking the
parameterization of the one order series expansion of the and
, is determined to be , and the
shape parameters of and are
and , respectively. Combining with the average
of and lattice calculaltion, the is extracted
to be where the first error is experimental and the
second theoretical. Alternatively, the is extracted to be
by taking the as the value from the global
fit with the unitarity constraint of the CKM matrix. Moreover, using the
obtained form factors by lattice QCD, we re-analyze these
measurements in the context of new physics. Constraints on scalar leptoquarks
are obtained for different final states of semileptonic
decays
Next-to-leading order QCD corrections to the top quark associated with production via model-independent flavor-changing neutral-current couplings at hadron colliders
We present the complete next-to-leading order (NLO) QCD corrections to the
top quark associated with production induced by model-independent
and flavor-changing neutral-current (FCNC) couplings at hadron
colliders, respectively. We also consider the mixing effects between the
and FCNC couplings for this process. Our results show that,
for the couplings, the NLO QCD corrections can enhance the total
cross sections by about 50% and 40% at the Tevatron and LHC, respectively.
Including the contributions from the , FCNC couplings and their
mixing effects, the NLO QCD corrections can enhance the total cross sections by
about 50% for the and FCNC couplings, and by about the 80% for
the and FCNC couplings at the LHC, respectively. Moreover, the
NLO corrections reduce the dependence of the total cross section on the
renormalization and factorization scale significantly. We also evaluate the NLO
corrections for several important kinematic distributions.Comment: 25 pages, 16 figure
Poly[trans-diaquabis[μ2-2-(pyridin-3-yl)acetato-κ2 N:O]zinc]
In the title coordination polymer, [Zn(C7H6NO2)2(H2O)2]n, the ZnII cation is located on an inversion center and is coordinated by four pyridylacetate anions and two water molecules in a distorted ZnN2O4 octahedral geometry. The pyridine-N and carboxylate-O atoms of the pyridylacetate anion connect to two ZnII cations, forming a two-dimensional polymeric complex extending parallel to (212). Intermolecular O—H⋯O and weak C—H⋯O hydrogen bonding is present in the crystal structure
Tris(5,6-dimethyl-1H-benzimidazole-κN 3)(pyridine-2,6-dicarboxylato-κ3 O 2,N,O 6)nickel(II)
The title mononuclear complex, [Ni(C7H3NO4)(C9H10N2)3], shows a central NiII atom which is coordinated by two carboxylate O atoms and the N atom from a pyridine-2,6-dicarboxylate ligand and by three N atoms from different 5,6-dimethyl-1H-benzimidazole ligands in a distorted octahedral geometry. The crystal structure shows intermolecular N—H⋯O hydrogen bonds
- …