2,109 research outputs found
with a warped bulk Higgs
We study the decay in Randall-Sundrum models with an
IR-localised bulk Higgs. The two models under consideration are a minimal model
as well as a model with a custodial protection mechanism. We include the
effects of tree- and one-loop diagrams involving 5D gluon and Higgs exchanges
as well as QCD corrections arising from the evolution from the Kaluza-Klein
scale to the typical scale of the decay. We find the RS corrections to the
branching fraction can be sizeable for large Yukawas and moderate KK scales
; for small Yukawas the RS contribution is small enough to be invisible in
current experimental data.Comment: 20 pages, 5 figures(V2: references added, matches version published
in Nuclear Physics B
Sudakov Resummations at Higher Orders
We summarize our recent results on the resummation of hard-scattering
coefficient functions and on-shell form factors in massless perturbative QCD.
The threshold resummation has been extended to the fourth logarithmic order for
deep-inelastic scattering, Drell-Yan lepton pair production and Higgs
production via gluon-gluon fusion. The leading six infrared pole terms have
been derived to all orders in the strong coupling constant for the
photon-quark-quark and the (heavy-top) Higgs-gluon-gluon form factors. These
results have many implications, most notably they lead to a new best estimate
for the Higgs production cross section at the LHC.Comment: 12 pages, LaTeX, 2 eps-figures. Uses modification appbav.cls
(included) of the appolb.cls style. Presented by S.M. and A.V. at the
conferences `Matter to the Deepest', Ustron (Poland), September '05, and
RADCOR 2005, Shonan Village (Japan), October '05. To appear, in the latter
case in shortened form, in the proceeding
Deep Inelastic Structure Functions at two Loops
We present the analytic calculation of the Mellin moments of the structure
functions F_2, F_3 and F_L in perturbative QCD up to second order corrections
and in leading twist approximation. We calculate the 2-loop contributions to
the anomalous dimensions of the singlet and non-singlet operator matrix
elements and the 2-loop coefficient functions of F_2, F_3 and F_L. We perform
the inverse Mellin transformation analytically and find our results in
agreement with earlier calculations in the literature by Zijlstra and van
Neerven.Comment: 45 pages LaTe
Strange sea determination from collider data
We consider determinations of the strange sea in the nucleon based on the QCD
analyses of data collected at the LHC with focus on the recent high-statistics
ATLAS measurement of the - and -boson production. We study the effect
of different functional forms for parameterization of the parton distribution
functions and the combination of various data sets in the analysis. We compare
to earlier strange sea determinations and discuss ways to improve them in the
future.Comment: 13 pages, 7 figure
Deep-inelastic structure functions: Reconstruction from Mellin moments
We summarize the method of calculating Mellin moments of deep-inelastic
structure functions in perturbative QCD. We briefly discuss all steps to a
complete analytical reconstruction of the perturbative corrrections in x-space.Comment: 6 pages LaTeX, presented at LL2000, Bastei (Germany
Lepton flavour violation in RS models with a brane- or nearly brane-localized Higgs
We perform a comprehensive study of charged lepton flavour violation in
Randall-Sundrum (RS) models in a fully 5D quantum-field-theoretical framework.
We consider the RS model with minimal field content and a "custodially
protected" extension as well as three implementations of the IR-brane localized
Higgs field, including the non-decoupling effect of the Kaluza-Klein (KK)
excitations of a narrow bulk Higgs. Our calculation provides the first complete
result for the flavour-violating electromagnetic dipole operator in
Randall-Sundrum models. It contains three contributions with different
dependence on the magnitude of the anarchic 5D Yukawa matrix, which can all be
important in certain parameter regions. We study the typical range for the
branching fractions of mu -> e gamma, mu -> 3e, mu N -> e N as well as tau ->
mu gamma, tau -> 3 mu and the electron electric dipole moment by a numerical
scan in both the minimal and the custodial RS model. The combination of mu -> e
gamma and mu N -> e N currently provides the most stringent constraint on the
parameter space of the model. A typical lower limit on the KK scale T is around
2 TeV in the minimal model (up to 4 TeV in the bulk Higgs case with large
Yukawa couplings), and around 4 TeV in the custodially protected model, which
corresponds to a mass of about 10 TeV for the first KK excitations, far beyond
the lower limit from the non-observation of direct production at the LHC.Comment: 64 pages, 21 figures, LaTeX, v2: electron EDM analysis added, matches
published versio
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