1,411 research outputs found
Neutral Higgs-Boson Pair Production at Hadron Colliders: QCD Corrections
Neutral Higgs-boson pair production provides the possibility of studying the
trilinear Higgs couplings at future high-energy colliders. We present the QCD
corrections to the gluon-initiated processes in the limit of a heavy top quark
in the loops and the Drell-Yan-like pair production of scalar and pseudoscalar
Higgs particles. The pp cross sections are discussed for LHC energies within
the Standard Model and its minimal supersymmetric extension. The QCD
corrections are large, enhancing the total cross sections significantly.Comment: 26 pages, latex, 9 ps figure
Exact Hybrid Covariance Thresholding for Joint Graphical Lasso
This paper considers the problem of estimating multiple related Gaussian
graphical models from a -dimensional dataset consisting of different
classes. Our work is based upon the formulation of this problem as group
graphical lasso. This paper proposes a novel hybrid covariance thresholding
algorithm that can effectively identify zero entries in the precision matrices
and split a large joint graphical lasso problem into small subproblems. Our
hybrid covariance thresholding method is superior to existing uniform
thresholding methods in that our method can split the precision matrix of each
individual class using different partition schemes and thus split group
graphical lasso into much smaller subproblems, each of which can be solved very
fast. In addition, this paper establishes necessary and sufficient conditions
for our hybrid covariance thresholding algorithm. The superior performance of
our thresholding method is thoroughly analyzed and illustrated by a few
experiments on simulated data and real gene expression data
Roots of the derivative of the Riemann zeta function and of characteristic polynomials
We investigate the horizontal distribution of zeros of the derivative of the
Riemann zeta function and compare this to the radial distribution of zeros of
the derivative of the characteristic polynomial of a random unitary matrix.
Both cases show a surprising bimodal distribution which has yet to be
explained. We show by example that the bimodality is a general phenomenon. For
the unitary matrix case we prove a conjecture of Mezzadri concerning the
leading order behavior, and we show that the same follows from the random
matrix conjectures for the zeros of the zeta function.Comment: 24 pages, 6 figure
MSSM Higgs Couplings to Bottom Quarks: Two-Loop Corrections
We present the two-loop SUSY-QCD corrections to the effective bottom Yukawa
couplings within the minimal supersymmetric extension of the Standard Model.
The effective Yukawa couplings include the resummation of the non-decoupling
corrections Delta m_b for large values of tg(beta). We have derived the
two-loop SUSY-QCD corrections to the leading SUSY-QCD and top-induced
SUSY-electroweak contributions to Delta m_b. The scale dependence of the
resummed Yukawa couplings is reduced from O(10%) to the per-cent level. These
results reduce the theoretical uncertainties of the MSSM Higgs branching ratios
to the accuracy which can be achieved at a future linear e+e- collider.Comment: 5 pages, 4 figure
Determining the Structure of Higgs Couplings at the LHC
Higgs boson production via weak boson fusion at the CERN Large Hadron
Collider has the capability to determine the dominant CP nature of a Higgs
boson, via the tensor structure of its coupling to weak bosons. This
information is contained in the azimuthal angle distribution of the two
outgoing forward tagging jets. The technique is independent of both the Higgs
boson mass and the observed decay channel.Comment: 5 pages, 4 figures, version accepted for publication in PR
Radiative Higgs Boson Decays H\to f\bar{f}\gamma Beyond the Standard Model
Neutral Higgs boson radiative decays of the form h_0, H, A \to
f\bar{f}\gamma, in the light fermion limit $m_f->0, are calculated in the two
Higgs doublet model at one-loop level. Comparisons with the calculation within
the standard model are given, which indicates that these two models are
distinguishable in the decay mode fermion-antifermion -photon. Our results show
that the concerned process may stand as an implement to identify the Higgs
belongings in case there is a intermediate mass Higgs detected.Comment: 13 pages in Revtex, version to appear in Phys. Rev.
Testing the Higgs boson gluonic couplings at LHC
We study Higgs + jet production at hadron colliders in order to look for new
physics residual effects possibly described by the operators
{\O}_{GG} and {\widetilde\O}_{GG} which induce anomalous and
couplings. Two ways for constraining these operators at LHC may be ~useful. The
first is based on the total Higgs boson production rate induced by gluon-gluon
fusion, in which the main cause of limitations are due to theoretical
uncertainties leading to sensitivities of and
for the corresponding anomalous
couplings, in the mass range 100 GeV \lsim \mh \lsim 2~00 GeV. These results
imply sensitivity to new physics scales of 51 and 24 TeV respectively. The
second way investigated here concerns the shape of the Higgs transverse
momentum; for which the theoretical uncertainties are less severe and the
limitations are mainly induced by statistics. A simple analysis, based on the
ratio of the number of events at large and low at LHC, leads to similar
sensitivities, if only the decay mode is used. But the
sensitivities can now be improved by a factor 2 to 10, depending on the Higgs
mass, if the Higgs decay modes to , , , are also used.Comment: 23 pages and 7 figures, version to appear in Phys.ReV.D. e-mail:
[email protected]
Rompimiento de la Simetria Electrodebil y la Fisica del Higgs: Conceptos Basicos
Presentamos una introduccion a los conceptos basicos del rompimiento de la
simetria electrodebil y la fisica del Higgs dentro del Modelo Estandar y sus
extensiones supersimetricas. Se presenta tambien una breve perspectiva general
de mecanismos alternativos del rompimiento de la simetria. Ademas de las bases
teoricas, se discute el estado actual de la fisica experimental del Higgs y sus
implicaciones para futuros experimentos en el LHC y en colisionadores lineales
e+e-.Comment: Spanish text, including full English translation. Published in the
Proceedings of the XI Mexican School on Particles and Fields, Xalapa,
Veracruz, Mexic
Higgs Physics: Theory
I review the theoretical aspects of the physics of Higgs bosons, focusing on
the elements that are relevant for the production and detection at present
hadron colliders. After briefly summarizing the basics of electroweak symmetry
breaking in the Standard Model, I discuss Higgs production at the LHC and at
the Tevatron, with some focus on the main production mechanism, the gluon-gluon
fusion process, and summarize the main Higgs decay modes and the experimental
detection channels. I then briefly survey the case of the minimal
supersymmetric extension of the Standard Model. In a last section, I review the
prospects for determining the fundamental properties of the Higgs particles
once they have been experimentally observed.Comment: 21 pages, 15 figures. Talk given at the XXV International Symposium
on Lepton Photon Interactions at High Energies (Lepton Photon 11), 22-27
August 2011, Mumbai, Indi
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