76 research outputs found
Higgs Boson Pair Production at Next-to-Next-to-Leading Order in QCD
We compute the next-to-next-to-leading order QCD corrections for Standard
Model Higgs boson pair production inclusive cross section at hadron colliders
within the large top-mass approximation. We provide numerical results for the
LHC, finding that the corrections are large, resulting in an increase of with respect to the next-to-leading order result at c.m. energy
. We observe a substantial reduction in the scale
dependence, with overlap between the current and previous order prediction. All
our results are normalized using the full top- and bottom-mass dependence at
leading order. We also provide analytical expressions for the K factors as a
function of
Two-loop virtual corrections to Higgs pair production
We present the two-loop virtual corrections to Standard Model Higgs boson
pair production via gluon fusion in the heavy top quark limit. Based
on this result, we evaluate the corresponding cross section at the LHC at 14
TeV in the next-to-next-to-leading order soft-virtual approximation. We find an
inclusive K-factor of about 2.4, resulting in an increase close to 23% with
respect to the previous available calculation at next-to-leading order. As
expected, we observe a considerable reduction in the renormalization and
factorization scale dependence
Next-to-Next-to-Leading Order QCD Corrections to Higgs Boson Pair Production
We present the Higgs boson pair production cross section at
next-to-next-to-leading order in QCD within the large top-mass approximation.
Numerical results for the LHC are provided, finding an increase of O(20%) with
respect to the previous order prediction and a substantial reduction in the
scale dependence. We normalize our results using the full top- and bottom-mass
dependence at leading order.Comment: Proceedings of 'Loops & Legs 2014', Weimar (Germany), April/May 201
Two-loop corrections to the triple Higgs boson production cross section
In this paper we compute the QCD corrections for the triple Higgs boson
production cross section via gluon fusion, within the heavy-top approximation.
We present, for the first time, analytical results for the next-to-leading
order corrections, and also compute the soft and virtual contributions of the
next-to-next-to-leading order cross section. We provide predictions for the
total cross section and the triple Higgs invariant mass distribution. We find
that the QCD corrections are large at both perturbative orders, and that the
scale uncertainty is substantially reduced when the second order perturbative
corrections are included.Comment: 12 pages, 4 figures. v2: added analysis for non-SM self-couplings,
and other minor corrections. To be published in JHE
A next-to-next-to-leading order calculation of soft-virtual cross sections
We compute the next-to-next-to-leading order (NNLO) soft and virtual QCD corrections for the partonic cross section of colourless-final state processes in hadronic collisions. The results are valid to all orders in the dimensional regularization parameter Ïμ. The dependence of the results on a particular process is given through finite contributions to the one and two-loop amplitudes, which have to be computed in a process-by-process basis. To evaluate the accuracy of the soft-virtual approximation we compare it with the full NNLO result for Drell-Yan and Higgs boson production via gluon fusion. We also provide a universal expression for the hard coefficient needed to perform threshold resummation up to next-to-next-to-leading logarithmic (NNLL) accuracy. © 2012 SISSA, Trieste, Italy.Fil: de Florian, Daniel Enrique. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Mazzitelli, Javier Sebastián. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin
Higgs pair production at next-to-next-to-leading logarithmic accuracy at the LHC
We perform the threshold resummation for Higgs pair production in the dominant gluon fusion channel to next-to-next-to-leading logarithmic (NNLL) accuracy. The calculation includes the matching to the next-to-next-to-leading order (NNLO) cross section obtained in the heavy top-quark limit, and results in an increase of the inclusive cross section up to 7% at the LHC with centre-of-mass energy Ecm = 14 TeV, for the choice of factorization and renormalization scales μF = μR = Q, being Q the invariant mass of the Higgs pair system. After the resummation is implemented, we estimate the theoretical uncertainty from the perturbative expansion to be reduced to about ±5.5%, plus ∼ 10% from finite top-mass effects. The resummed cross section turns out to be rather independent of the value chosen for the central factorization and renormalization scales in the usual range (Q/2, Q).Fil: de Florian, Daniel Enrique. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mazzitelli, Javier Sebastián. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Higgs boson pair production at NNLO in QCD including dimension 6 operators
In this paper, we present the computation of the Higgs boson pair production
cross section, both inclusive as well as differential on the invariant mass
distribution, at next-to-next-to-leading order (NNLO) in QCD including effects
of new physics beyond the standard model. We parametrize the effects of new
physics with the relevant dimension 6 operators in a standard model effective
field theory (EFT) approach and examine their phenomenology. The dependence of
the NNLO -factor on the EFT couplings is analysed, finding that, while
rather flat for a number of EFT coefficients, it can considerably differ from
the standard model value in some particular regions of the parameter space. We
present explicit examples of (almost) degeneracy in the NNLO cross-section with
respect to the anomalous couplings, showing that the invariant mass
distribution has a much larger sensitivity to phenomena beyond the standard
model and can be used as a tool to discriminate their effect.Comment: 19 pages, 4 figures; typos corrected, references added, appendix with
additional formulae adde
Next-to-Next-to-Leading Order QCD Corrections in Models of TeV-Scale Gravity
We compute the next-to-next-to-leading order QCD corrections to the graviton
production in models of TeV-scale gravity, within the soft-virtual
approximation.
For the Arkani-Hamed, Dimopoulos and Dvali (ADD) model we evaluate the
contribution to the Drell-Yan cross section, and we present distributions for
the di-lepton invariant mass at the LHC with a center-of-mass energy
. We find a large factor () for large
values of invariant mass, which is the region where the ADD graviton
contribution dominates the cross section. The increase in the cross section
with respect to the previous order result is larger than in the same
invariant mass region. We also observe a substantial reduction in the scale
uncertainty.
For the Randall-Sundrum (RS) model we computed the total single graviton
production cross section at the LHC. We find an increase between and
with respect to the next-to-leading order prediction, depending on the
model parameters. We provide an analytic expression for the NNLO factor as
a function of the lightest RS graviton mass.Comment: 16 pages, 7 figure
Quark and gluon spin-2 form factors to two-loops in QCD
We present complete two-loop radiative corrections to the
graviton-quark-antiquark form factor G^* \rightarrow q \overline q and
graviton-gluon-gluon form factor G^* \rightarrow g g in SU(N) gauge theory with
n_f light flavours using d-dimensional regularisation to all orders in
\varepsilon=d-4. This is an important ingredient to next-to-next-to-leading
order QCD corrections to hadronic scattering processes in models with large
extra-dimensions where Kaluza-Klein graviton modes couple to Standard Model
fields. We show that these form factors obey Sudakov integro-differential
equation and the resulting cusp, collinear and soft anomalous dimensions
coincide with those of electroweak vector boson and gluon form factors. We also
find the universal behaviour of the infrared singularities in accordance with
the proposal by Catani.Comment: 14 pages, LaTeX; references added, version to appear in JHE
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