1,202 research outputs found
Masses of Scalar and Axial-Vector B Mesons Revisited
The SU(3) quark model encounters a great challenge in describing even-parity
mesons. Specifically, the quark model has difficulties in
understanding the light scalar mesons below 1 GeV, scalar and axial-vector
charmed mesons and charmonium-like state . A common wisdom for
the resolution of these difficulties lies on the coupled channel effects which
will distort the quark model calculations. In this work, we focus on the near
mass degeneracy of scalar charmed mesons, and , and its
implications. Within the framework of heavy meson chiral perturbation theory,
we show that near degeneracy can be qualitatively understood as a consequence
of self-energy effects due to strong coupled channels. Quantitatively, the
closeness of and masses can be implemented by adjusting
two relevant strong couplings and the renormalization scale appearing in the
loop diagram. Then this in turn implies the mass similarity of and
mesons. The interaction with the Goldstone boson is
crucial for understanding the phenomenon of near degeneracy. Based on heavy
quark symmetry in conjunction with corrections from QCD and effects, we
obtain the masses of and mesons, for example,
,
with being
corrections. We find that the predicted mass difference of 48 MeV
between and is larger than that of MeV
inferred from the relativistic quark models, whereas the difference of 15 MeV
between the central values of and is much smaller than
the quark model expectation of MeV.Comment: 21 pages, 1 figure, to appear in Eur. Phys. J. (2017). arXiv admin
note: text overlap with arXiv:1404.377
Dithiolopyrrolone Natural Products : Isolation, Synthesis and Biosynthesis
Peer reviewedPublisher PD
Resummation Prediction on Higgs and Vector Boson Associated Production with a Jet Veto at the LHC
We investigate the resummation effects for the SM Higgs and vector boson
associated production at the LHC with a jet veto in soft-collinear effective
theory using "collinear anomalous" formalism. We calculate the jet vetoed
invariant mass distribution and the cross section for this process at
Next-to-Next-to-Leading-Logarithmic level, which are matched to the QCD
Next-to-Leading Order results, and compare the differences of the resummation
effects with different jet veto and jet radius . Our
results show that both resummation enhancement effects and the scale
uncertainties decrease with the increasing of jet veto and
jet radius , respectively. When GeV and ,
the resummation effects reduce the scale uncertainties of the Next-to-Leading
Order jet vetoed cross sections to about , which lead to increased
confidence on the theoretical predictions. Besides, after including resummation
effects, the PDF uncertainties of jet vetoed cross section are about .Comment: 22 pages, 10 figures and 2 tables; final version in JHE
Soft gluon resummation in the signal-background interference process of
We present a precise theoretical prediction for the signal-background
interference process of , which is useful to constrain the
Higgs boson decay width and to measure Higgs couplings to the SM particles. The
approximate NNLO -factor is in the range of (),
depending on , at the 8 (13) TeV LHC. And the soft gluon resummation
can increase the approximate NNLO result by about at both the 8 TeV and
13 TeV LHC. The theoretical uncertainties including the scale, uncalculated
multi-loop amplitudes of the background and PDF are roughly
at . We also confirm that the approximate
-factors in the interference and the pure signal processes are the same.Comment: 18 pages, 9 figures; v2 published in JHE
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