8,696 research outputs found
Triple and quartic interactions of Higgs bosons in the two-Higgs-doublet model with CP violation
We consider the two-Higgs-doublet model with explicit CP-violation, where the
effective Higgs potential is not CP-invariant at the tree-level. Three neutral
Higgs bosons of the model are the mixtures of CP-even and CP-odd bosons which
exist in the CP-conserving limit of the theory. The mass spectrum and
tree-level couplings of the neutral Higgs bosons to gauge bosons and fermions
are significantly dependent on the parameters of the Higgs boson mixing matrix.
We calculate the Higgs-gauge boson, Higgs-fermion, triple and quartic Higgs
self-interactions in the MSSM with explicit CP-violation in the Higgs sector
and CP-violating Yukawa interactions of the third generation scalar quarks. In
some regions of the MSSM parameter space substantial changes of the
self-interaction vertices take place, leading to significant suppression or
enhancement of the multiple Higgs boson production cross sections.Comment: 29 pages, 4 figures. Minor changes in section 3, misprints in (47)
corrected. Version accepted by EPJ
Mott-Anderson freeze-out and the strange matter "horn"
We discuss the -dependence of the ratio in heavy-ion
collisions (the "horn" effect) within a Mott-Anderson localization model for
chemical freeze-out. The different response of pion and kaon radii to the hot
and dense hadronic medium results in different freeze-out conditions. We
demonstrate within a simple model that this circumstance enhances the "horn"
effect relative to statistical models with universal chemical freeze-out.Comment: 8 pages, 4 figure
A possible search for Majorana neutrinos at future lepton colliders
We discuss the process , where is
a heavy Majorana neutrino and . Large cross sections are
expected for these processes at high center-of-mass energies, which can be
reached at future lepton-lepton colliders. The Monte Carlo simulation of the
studied processes is produced within the framework of the seesaw type-I model,
where the Majorana neutrinos (or heavy neutral leptons, HNL), are introduced in
the standard leptonic sector. Recently the possibility to search for the direct
HNL production was studied in the process with
the subsequent decay . In this paper we investigate
an alternative process with the lepton number violation by two
units. The similar processes appear in collisions with the same-sign beams,
or . The cross sections of the processes under
consideration are enhanced by the soft photon exchange in the -channel. We
calculate the cross sections for the signals and potential Standard Model
backgrounds for the beam collisions at the 1 TeV center-of-mass energy
and the collisions at 3 TeV and 10 TeV. Due to the diagrams with
soft -channel photons and respective interference the promptly emitted
leptons are produced in the direction close to the corresponding beam. These
leptons will be lost in the beam pipe or badly measured by forward detectors.
However, the signal events can be well separated from backgrounds using the
rest of the event containing the particles. Finally, the expected
upper limits on the mixing parameters as a function of M()
are calculated.Comment: 8 pages, 5 figures, 3 table
CompHEP 4.4 - Automatic Computations from Lagrangians to Events
We present a new version of the CompHEP program (version 4.4). We describe
shortly new issues implemented in this version, namely, simplification of quark
flavor combinatorics for the evaluation of hadronic processes, Les Houches
Accord based CompHEP-PYTHIA interface, processing the color configurations of
events, implementation of MSSM, symbolical and numerical batch modes, etc. We
discuss how the CompHEP program is used for preparing event generators for
various physical processes. We mention a few concrete physics examples for
CompHEP based generators prepared for the LHC and Tevatron.Comment: The paper has been presented on IX International Workshop on Advanced
Computing and Analysis Techniques in Physics Research December 1-5, 2003.
KEK, Japan. 10 pages, 2 figure
Search for the standard model Higgs boson in the H → ZZ → ℓ^+ℓ^−τ^+τ^− decay channel in pp collisions at √s = 7 TeV
A search is reported for the standard model Higgs boson in the H → ZZ → ℓ^+ℓ^−τ^+τ^− decay mode, where ℓ = μ or e, in proton-proton collisions at √s = 7TeV , corresponding to an integrated luminosity of 4.7 fb^(−1) collected with the CMS detector at the LHC. No evidence is found for a significant deviation from the background expectation. An upper limit four to twelve times larger than the predicted value is set at 95% confidence level for the product of the standard model Higgs boson production cross section and decay branching fraction in the mass range 190 < m_H < 600 GeV
Modeling the process of producing hydrogen from methane
Using the chemical reactions that accompany the production of syngas via the steam reforming of methane as a basis, the differential material balance equations were derived and solved for all conversion products on an aluminum/nickel catalyst. For the following stage of hydrogen synthesis on an iron/chromium catalyst, the system of two differential equations of the material balance of the direct and reverse reactions of steam carbon monoxide conversion was obtained and solved. The analytical solutions were compared with the experiment. © 2013 Pleiades Publishing, Ltd
The Structure of Martian Magnetosphere at the Dayside Terminator Region as Observed on MAVEN Spacecraft
We analyzed 44 passes of the MAVEN spacecraft through the magnetosphere,
arranged by the angle between electric field vector and the projection of
spacecraft position radius vector in the YZ plane in MSE coordinate system
( E ). All passes were divided into 3 angular sectors near 0{\deg},
90{\deg} and 180{\deg} E angles in order to estimate the role of IMF
direction in plasma and magnetic properties of dayside Martian magnetosphere.
The time interval chosen was from January 17 through February 4, 2016 when
MAVEN was crossing the dayside magnetosphere at SZA ~ 70{\deg}. Magnetosphere
as the region with prevailing energetic planetary ions is always found between
the magnetosheath and the ionosphere. 3 angular sectors of dayside interaction
region in MSE coordinate system with different orientation of the solar wind
electric field vector E = -1/c V x B showed that for each sector one can find
specific profiles of the magnetosheath, the magnetic barrier and the
magnetosphere. Plume ions originate in the northern MSE sector where motion
electric field is directed from the planet. This electric field ejects
magnetospheric ions leading to dilution of magnetospheric heavy ions
population, and this effect is seen in some magnetospheric profiles. Magnetic
barrier forms in front of the magnetosphere, and relative magnetic field
magnitudes in these two domains vary. The average height of the boundary with
ionosphere is ~530 km and the average height of the magnetopause is ~730 km. We
discuss the implications of the observed magnetosphere structure to the
planetary ions loss mechanism.Comment: 24 pages, 13 figure
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