Weak radiative decays of the B mesons belong to the most important flavor changing processes that provide constraints on physics at the TeV scale. In the derivation of such constraints, accurate ...standard model predictions for the inclusive branching ratios play a crucial role. In the current Letter we present an update of these predictions, incorporating all our results for the O(α_{s}^{2}) and lower-order perturbative corrections that have been calculated after 2006. New estimates of nonperturbative effects are taken into account, too. For the CP- and isospin-averaged branching ratios, we find B_{sγ}=(3.36±0.23)×10^{-4} and B_{dγ}=(1.73_{-0.22}^{+0.12})×10^{-5}, for E_{γ}>1.6 GeV. Both results remain in agreement with the current experimental averages. Normalizing their sum to the inclusive semileptonic branching ratio, we obtain R_{γ}≡(B_{sγ}+B_{dγ})/B_{cℓν}=(3.31±0.22)×10^{-3}. A new bound from B_{sγ} on the charged Higgs boson mass in the two-Higgs-doublet-model II reads M_{H^{±}}>480 GeV at 95% C.L.
High-energy jets recoiling against missing transverse energy (MET) are powerful probes of dark matter at the LHC. Searches based on large MET signatures require a precise control of the
Z
(
ν
ν
¯
)
+
... jet background in the signal region. This can be achieved by taking accurate data in control regions dominated by
Z
(
ℓ
+
ℓ
-
)
+
jet,
W
(
ℓ
ν
)
+
jet and
γ
+
jet production, and extrapolating to the
Z
(
ν
ν
¯
)
+
jet background by means of precise theoretical predictions. In this context, recent advances in perturbative calculations open the door to significant sensitivity improvements in dark matter searches. In this spirit, we present a combination of state-of-the-art calculations for all relevant
V
+
jets processes, including throughout NNLO QCD corrections and NLO electroweak corrections supplemented by Sudakov logarithms at two loops. Predictions at parton level are provided together with detailed recommendations for their usage in experimental analyses based on the reweighting of Monte Carlo samples. Particular attention is devoted to the estimate of theoretical uncertainties in the framework of dark matter searches, where subtle aspects such as correlations across different
V
+
jet processes play a key role. The anticipated theoretical uncertainty in the
Z
(
ν
ν
¯
)
+
jet background is at the few percent level up to the TeV range.
We present an analytical calculation of the leading three-loop radiative correction to the
ρ-parameter in the Standard Model in the large Higgs mass limit. This correction, of order
g
6
m
H
4
/
M
W
4
..., is opposite in sign to the leading two-loop correction of order
g
4
m
H
2
/
M
W
2
. The two corrections cancel each other for a Higgs mass of approximately
480
GeV
. The result shows that it is extremely unlikely that a strongly interacting Higgs sector could fit the data of electroweak precision measurements.
We present a new set of high precision numerical values of four-loop single-scale vacuum integrals, which we subsequently use to obtain the non-singlet corrections to the
ρ parameter at
O
(
G
F
m
t
2
...α
s
3
)
. Our result for Δ
ρ is in agreement with the recent calculation K.G. Chetyrkin, M. Faisst, J.H. Kuhn, P. Maierhofer, C. Sturm,
hep-ph/0605201.
Abstract High-energy jets recoiling against missing transverse energy (MET) are powerful probes of dark matter at the LHC. Searches based on large MET signatures require a precise control of the ...$$Z(\nu {\bar{\nu }})+$$ Z ( ν ν ¯ ) + jet background in the signal region. This can be achieved by taking accurate data in control regions dominated by $$Z(\ell ^+\ell ^-)+$$ Z ( ℓ + ℓ - ) + jet, $$W(\ell \nu )+$$ W ( ℓ ν ) + jet and $$\gamma +$$ γ + jet production, and extrapolating to the $$Z(\nu {\bar{\nu }})+$$ Z ( ν ν ¯ ) + jet background by means of precise theoretical predictions. In this context, recent advances in perturbative calculations open the door to significant sensitivity improvements in dark matter searches. In this spirit, we present a combination of state-of-the-art calculations for all relevant $$V+$$ V + jets processes, including throughout NNLO QCD corrections and NLO electroweak corrections supplemented by Sudakov logarithms at two loops. Predictions at parton level are provided together with detailed recommendations for their usage in experimental analyses based on the reweighting of Monte Carlo samples. Particular attention is devoted to the estimate of theoretical uncertainties in the framework of dark matter searches, where subtle aspects such as correlations across different $$V+$$ V + jet processes play a key role. The anticipated theoretical uncertainty in the $$Z(\nu {\bar{\nu }})+$$ Z ( ν ν ¯ ) + jet background is at the few percent level up to the TeV range.
A
bstract
We report on a calculation of the cross-section for Higgs boson production in gluon fusion in association with a hadronic jet at next-to-next-to-leading order (NNLO) in perturbative QCD. ...The computational technique is discussed in detail. We show explicitly how to employ known soft and collinear limits of scattering amplitudes to construct subtraction terms for NNLO computations. Cancellation of singularities is demonstrated numerically for the collinearly-subtracted
gg
→
H
+
j
cross-section through NNLO and the finite
σ
gg→Hj
cross-section is computed through
as a function of the center-of-mass collision energy. We present numerical results for the gluon-fusion contribution to Higgs production in association with a jet at the LHC. The NNLO QCD corrections significantly reduce the residual scale dependence of the cross-section. The computational method that we describe in this paper is applicable to the calculation of NNLO QCD corrections to any other 2 → 2 process at a hadron collider without modification.
The antenna subtraction formalism allows to calculate QCD corrections to jet observables. Within this formalism, the subtraction terms are constructed using antenna functions describing all ...unresolved radiation between a pair of hard radiator partons. In this paper, we focus on the subtraction terms for double real radiation contributions to jet observables in hadron-hadron collisions evaluated at NNLO. An essential ingredient to these subtraction terms are the four-parton antenna functions with both radiators in the initial state. We outline the construction of the double real subtraction terms, classify all relevant antenna functions and describe their integration over the relevant antenna phase space. For the initial-initial antenna functions with two quark flavours, we derive the phase space master integrals and obtain the integrated antennae.
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