404 research outputs found
A numerical test of the Y-system in the small size limit of the SU(2)x SU(2) Principal Chiral Model
Recently, Kazakov, Gromov and Vieira applied the discrete Hirota dynamics to
study the finite size spectra of integrable two dimensional quantum field
theories. The method has been tested from large values of the size L down to
moderate values using the SU(2) x SU(2) principal chiral model as a theoretical
laboratory. We continue the numerical analysis of the proposed non-linear
integral equations showing that the deep ultraviolet region L -> 0 is
numerically accessible. To this aim, we introduce a relaxed iterative algorithm
for the numerical computation of the low-lying part of the spectrum in the U(1)
sector. We discuss in details the systematic errors involved in the
computation. When a comparison is possible, full agreement is found with
previous TBA computations.Comment: 28 pages, 24 figure
Neutral Higgs-pair production at Linear Colliders within the general 2HDM: quantum effects and triple Higgs boson self-interactions
The pairwise production of neutral Higgs bosons is analyzed in the context of
the future linear colliders, such as the ILC and CLIC, within the general
Two-Higgs-Doublet Model (2HDM). The corresponding cross-sections are computed
at the one-loop level in full compliance with the current phenomenological
bounds and the stringent theoretical constraints inherent to the consistency of
the model. We uncover regions across the 2HDM parameter space, mainly for low
tan\beta near 1 and moderate values of the relevant lambda_5 parameter, wherein
the radiative corrections to the Higgs-pair production cross sections can
comfortably reach 50% This behavior can be traced back to the enhancement
capabilities of the trilinear Higgs self-interactions -- a trademark feature of
the 2HDM, with no counterpart in the Minimal Supersymmetric Standard Model.
Interestingly enough, the quantum effects are positive for energies around 500
GeV, thereby producing a significant enhancement in the expected number of
events precisely around the fiducial startup energy of the ILC. The Higgs-pair
production rates can be substantial, typically amounting to a few thousand
events per 500 inverse femtobarn of integrated luminosity. In contrast, the
corrections are negative in the highest energy range (1 TeV). We also compare
the exclusive pairwise production of Higgs bosons with the inclusive gauge
boson fusion channels leading to 2H+X finals states, and also with the
exclusive triple Higgs boson production. We find that these multiparticle final
states can be highly complementary in the overall Higgs bosons search strategy.Comment: 42 pages, 23 figures, 10 tables. Accepted in Phys. Rev. D (the
published version is shorter
Quantum effects on Higgs-strahlung events at Linear Colliders within the general 2HDM
The associated production of neutral Higgs bosons with the Z gauge boson is
investigated in the context of the future linear colliders, such as the ILC and
CLIC, within the general two-Higgs-doublet model (2HDM). We compute the
corresponding production cross-sections at one-loop, in full consistency with
the available theoretical and phenomenological constraints. We find that the
wave-function renormalization corrections to the external Higgs fields are the
dominant source of the quantum effects, which turn out to be large and
negative, and located predominantly in the region around \tan\beta=1 and
moderate values of the parameter \lambda_5 (being \lambda_5 < 0). This behavior
can be ultimately traced back to the enhancement potential of the triple Higgs
boson self-couplings, a trademark feature of the 2HDM with no counterpart in
the Higgs sector of the Minimal Supersymmetric Standard Model. The predicted
Higgs-strahlung rates comfortably reach a few tens of femtobarn, which means
barely 10^3 - 10^4 events per 500 inverse femtobarn of integrated luminosity.
Due to their great complementarity, we argue that the combined analysis of the
Higgs-strahlung events and the previously computed one-loop Higgs-pair
production processes could be instrumental to probe the structure of the Higgs
sector at future linac facilities.Comment: LaTeX, 16 pages, 9 Figures, 2 Tables. Extended discussion, references
added, matches published version in Phys. Rev.
Production of neutral MSSM Higgs bosons in collisions: a complete 1-loop calculation
We present the first complete 1-loop diagrammatic calculation of the cross
sections for the neutral Higgs production processes e^+e^-\ra Z^0h^0 and
e^+e^-\ra A^0h^0 in the minimal supersymmetric standard model. We compare the
results from the diagrammatic calculation with the corresponding ones of the
simpler and compact effective potential approximation and discuss the typical
size of the differences.Comment: LaTeX, 16 pages, 8 figures appended in a uuencoded file, complete
PostScript file available at
http://itpaxp1.physik.uni-karlsruhe.de/prep/KA-TP-16-1995/KA-TP-16-199
Amicus Brief of Economists Ackerman et al. in Entergy v. Riverkeepers
A group of academic economists filed this amicus brief in a pending Supreme Court case, Entergy v. Riverkeepers. The amicus brief addresses questions pertaining to the nature and limits of cost-benefit analysis (CBA) and thus contributes to the ongoing scholarly debate about CBA\u27s role in environmental law. The case raises the question of whether EPA may consider CBA in writing standards based on the best technology available for minimizing environmental impacts from intake of water to cool industrial facilities. This intake kills fish and disrupts eco-systems. The brief explains that cost-benefit balancing may be inappropriate for an agency implementing foundational normative commitments embodied in the constitution or legislation. It then argues that engineering analysis identifies the best technology and financial analysis comparing costs to the regulated industry\u27s economic capabilities (rather than to benefits) assesses a technology\u27s availability. Finally, the brief explains that the radical incompleteness of the CBA done in this case could have been avoided by using a traditional technology-based approach
On loss aversion in bimatrix games
ABSTRACT. In this article three different types of loss aversion equilibria in bimatrix games are studied. Loss aversion equilibria are Nash equilibria of games where players are loss averse and where the reference points-points below which they consider payoffs to be lossesare endogenous to the equilibrium calculation. The first type is the fixed point loss aversion equilibrium, introduced in Shalev (2000; Int. J. Game Theory 29(2):269) under the name of 'myopic loss aversion equilibrium.' There, the players' reference points depend on the beliefs about their opponents' strategies. The second type, the maximin loss aversion equilibrium, differs from the fixed point loss aversion equilibrium in that the reference points are only based on the carriers of the strategies, not on the exact probabilities. In the third type, the safety level loss aversion equilibrium, the reference points depend on the values of the own payoff matrices. Finally, a comparative statics analysis is carried out of all three equilibrium concepts in 2 × 2 bimatrix games. It is established when a player benefits from his opponent falsely believing that he is loss averse
The Higgs Boson Production Cross Section as a Precision Observable?
We investigate what can be learned at a linear collider about the sector of
electroweak symmetry breaking from a precise measurement of the Higgs boson
production cross section through the process e+e- -> hZ. We focus on deviations
from the Standard Model arising in its minimal supersymmetric extension. The
analysis is performed within two realistic future scenarios, taking into
account all prospective experimental errors on supersymmetric particle masses
as well as uncertainties from unknown higher order corrections. We find that
information on tan beta and M_A could be obtained from a cross section
measurement with a precision of 0.5 - 1 %. Alternatively, information could be
obtained on the gaugino mass parameters M_2 and mu if they are relatively
small, M_2, mu approximately 200 GeV.Comment: 13 pages, 3 figures. Discussion on experimental errors enlarged,
references added and updated. Version to appear in Phys. Rev.
On loss aversion in bimatrix games
In this paper we study three different types of loss aversion equi-libria in bimatrix games. Loss aversion equilibria are Nash equilibria of games where players are loss averse and where the reference points – points below which they consider payoffs to be losses – are endoge-nous to the equilibrium calculation. The first type is the fixed point loss aversion equilibrium, introduced in Shalev (2000) under the name of ‘myopic loss aversion equilibrium’. There, the players’ reference points depend on the beliefs about their opponents ’ strategies. The second type, the maximin loss aversion equilibrium, differs from the fixed point loss aversion equilibrium in that the reference point is now only based on the carrier of the players’ beliefs, not on the exact prob-abilities. In the third, the safety level loss aversion equilibrium, this dependence is completely dispensed with. Finally, we do a compara-tive statics analysis of all three equilibrium concepts in 2 × 2 bimatrix games. The results indicate that a player, under some conditions, benefits from his opponent falsely believing he is loss averse
- …