1,888 research outputs found
Electroweak and Bottom Quark Contributions to Higgs Boson plus Jet Production
This paper presents predictions for jet pseudorapidity (eta) and transverse
momentum (p_T) distributions for the production of the Standard Model Higgs
boson in association with a high-p_T hadronic jet. We discuss the contributions
of electroweak loops and of bottom-quark parton processes to the cross section.
The latter arise in the five-flavour scheme. Predictions for the Tevatron and
the Large Hadron Collider with 10 TeV collision energy are presented. For Higgs
boson masses of 120 GeV, 160 GeV and 200 GeV, we find the maximal effects of
the electroweak contributions to the Higgs plus jet p_T and eta distribution to
be -14 % and -5.3 %, respectively, for the Tevatron, and -3 % and -2 %,
respectively, for the LHC. For the maximal contribution of bottom-quark parton
processes to the p_T and eta distribution, we find +3 % and + 2.5 %,
respectively, for the Tevatron, and +3.5 % and +3 %, respectively, for the LHC.
A separate study of the Higgs + b-jet cross section demonstrates that a
calculational approach which respects the hierarchies of Yukawa couplings
yields a leading order cross section prediction which is more accurate in the
high-p_T regime than conventional approaches.Comment: 25 pages, 14 figure
On topological defect formation in the process of symmetry breaking phase transitions
By resorting to some results in quantum field theories with spontaneous
breakdown of symmetry we show that an explanation based on microscopic dynamics
can be given of the fact that topological defect formation is observed during
the process of non-equilibrium phase transitions characterized by a non-zero
order parameter. We show that the Nambu-Goldstone particle acquires an
effective non-zero mass due to the boundary (finite volume) effects and this is
related with the size of the defect. We also relate such volume effect with
temperature effect.Comment: 12 pages, no figure
Bloch-Nordsieck Violation in Spontaneously Broken Abelian Theories
We point out that, in a spontaneously broken U(1) gauge theory, inclusive
processes, whose primary particles are mass eigenstates that do not coincide
with the gauge eigenstates, are not free of infrared logarithms. The charge
mixing allowed by symmetry breaking and the ensuing Bloch-Nordsieck violation
are here analyzed in a few relevant cases and in particular for processes
initiated by longitudinal gauge bosons. Of particular interest is the example
of weak hypercharge in the Standard Model where, in addition, left-right mixing
effects arise in transversely polarized fermion beams.Comment: 4 pages, 1 figur
A viability criterion for modified gravity with an extra force
A recently proposed theory of modified gravity with an explicit ``anomalous''
coupling of the Ricci curvature to matter is discussed, and an inequality is
derived which expresses a necessary and sufficient condition to avoid the
notorius Dolgov-Kawasaki instability.Comment: 4 latex pages, to appear in Phys. Rev.
Gravitation Interaction and Electromagnetic Interaction in the Relativistic Universe with Total Zero and Local Non-Zero Energy
In the model of flat expansive homogeneous and isotropic relativistic
universe with total zero and local non-zero energy the gravitation energy of
bodies and the elecromagnetic energy of charged bodies can be localised.Comment: LaTeX, 10 pages, 1 figur
Quantum Oscillator on \DC P^n in a constant magnetic field
We construct the quantum oscillator interacting with a constant magnetic
field on complex projective spaces \DC P^N, as well as on their non-compact
counterparts, i. e. the dimensional Lobachewski spaces . We
find the spectrum of this system and the complete basis of wavefunctions.
Surprisingly, the inclusion of a magnetic field does not yield any qualitative
change in the energy spectrum. For the magnetic field does not break the
superintegrability of the system, whereas for N=1 it preserves the exact
solvability of the system.
We extend this results to the cones constructed over \DC P^N and , and perform the (Kustaanheimo-Stiefel) transformation of these systems
to the three-dimensional Coulomb-like systems.Comment: 9 pages, 1 figur
Possibility of the new type phase transition
The scalar field theory and the scalar electrodynamics quantized in the flat
gap are considered. The dynamical effects arising due to the boundary presence
with two types of boundary conditions (BC) satisfied by scalar fields are
studied. It is shown that while the Neumann BC lead to the usual scalar field
mass generation, the Dirichlet BC give rise to the dynamical mechanism of
spontaneous symmetry breaking. Due to the later, there arises the possibility
of the new type phase transition from the normal to spontaneously broken phase.
The decreasing in the characteristic size of the quantization region (the gap
size here) and increasing in the temperature compete with each other, tending
to transport the system in the spontaneously broken and in the normal phase,
respectively. The system evolves with a combined parameter, simultaneously
reflecting the change in temperature and in the size. As a result, at the
critical value of this parameter there occurs the phase transition from the
normal phase to the spontaneously broken one. In particular, the usual massless
scalar electrodynamics transforms to the Higgs model
Probing the Higgs mechanism via
We investigate the sensitivity of the reaction to
the Higgs sector based on the complete one-loop corrections in the minimal
Standard Model and the gauged non-linear -model. While this sensitivity
is very strong for the suppressed cross-section of equally polarized photons
and longitudinal W bosons, it is only marginal for the dominant mode of
transverse polarizations. The corrections within the -model turn out to
be UV-finite in accordance with the absence of \log\MH terms in the Standard
Model with a heavy Higgs boson.Comment: 12 pages uuencoded postscrip
The Triple Higgs Boson Self-Coupling at Future Linear e+e- Colliders Energies: ILC and CLIC
We analyzed the triple Higgs boson self-coupling at future
colliders energies, with the reactions . We evaluate the total cross-sections for both and ,
and calculate the total number of events considering the complete set of
Feynman diagrams at tree-level. We vary the triple coupling
within the range and +2. The numerical
computation is done for the energies expected to be available at a possible
Future Linear Collider with a center-of-mass energy and a luminosity 1000 . Our analysis is also extended to a
center-of-mass energy 3 and luminosities of 1000 and 5000
. We found that for the process , the
complete calculation differs only by 3% from the approximate calculation
, while for the process , the expected number of events, considering the decay products of both
and , is not enough to obtain an accurate determination of the triple Higgs
boson self-coupling.Comment: 19 pages, 12 figure
Higgs Radiation off Top Quarks at the Tevatron and the LHC
Higgs bosons can be searched for in the channels
at the Tevatron and the LHC. We have calculated the QCD corrections to these
processes in the Standard Model at next-to-leading order. The higher-order
corrections reduce the renormalization and factorization scale dependence
considerably and stabilize the theoretical predictions for the cross sections.
At the central scale the properly defined factors are
slightly below unity for the Tevatron () and slightly above unity
for the LHC ().Comment: 5 pages, latex, 2 figure
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