2,214 research outputs found
Top pair Asymmetries at Hadron colliders with general couplings
Recently it has been shown that measurement of charge asymmetry of top pair
production at LHC excludes any flavor violating vector gauge boson that
could explain Tevatron forward-backward asymmetry (FBA). We consider the
general form of a gauge boson including left-handed, right-handed vector
and tensor couplings to examine FBA and charge asymmetry. To evaluate top pair
asymmetries at Tevatron and LHC, we consider mixing constraints on
flavor changing couplings and show that this model still explain
forward-backward asymmetry at Tevatron and charge asymmetry can not exclude it
in part of parameters space.Comment: 18 pages, 7 figure
Top Quark Physics at the LHC: A Review of the First Two Years
This review summarizes the highlights in the area of top quark physics
obtained with the two general purpose detectors ATLAS and CMS during the first
two years of operation of the Large Hadron Collider LHC. It covers the 2010 and
2011 data taking periods, where the LHC provided pp collisions at a
center-of-mass energy of sqrt(s)=7 TeV. Measurements are presented of the total
and differential top quark pair production cross section in many different
channels, the top quark mass and various other properties of the top quark and
its interactions, for instance the charge asymmetry. Measurements of single top
quark production and various searches for new physics involving top quarks are
also discussed. The already very precise experimental data are in good
agreement with the standard model.Comment: 107 pages, invited review for Int. J. Mod. Phys. A, v2 is identical
to v1 except for the addition of the table of content
Two-loop SUSY QCD corrections to the chargino masses in the MSSM
We have calculated the two-loop strong interaction corrections to the
chargino pole masses in the DRbar'-scheme in the Minimal Supersymmetric
Standard Model (MSSM) with complex parameters. We have performed a detailed
numerical analysis for a particular point in the parameter space and found
corrections of a few tenths of a percent. We provide a computer program which
calculates chargino and neutralino masses with complex parameters including the
one-loop corrections and all two-loop SQCD effects.Comment: 12 pages, 11 figures, references modified, clarifications adde
Rare Decay of the Top t->c l lbar and Single Top Production at International Linear Collider
We perform a complete and detailed analysis of the flavor changing neutral
current rare top quark decays t-> cl+l- and t->c nu_i bar nu_i at one-loop
level in the Standard Model, Two Higgs Doublet Models (I and II) and in MSSM.
The branching ratios are very small in all models, O(10^-14), except for the
case of the unconstrained MSSM, where they can reach O(10^-6) for e+e- and nu_i
bar nu_i, and O(10^-5) for tau+ tau-. This branching ratio is comparable to the
ones for t-> c V, cH. We also study the production rates of single top and the
forward-backward asymmetry in e+e- -> t cbar and comment on the observability
of such a signal at the International Linear Collider.Comment: 32 pages and 18 figures, minor clarification in the text, references
added. To be published in Phys. Rev.
Bibliometric Analysis and Review of Low and Medium Enthalpy Geothermal Energy: Environmental, Economic, and Strategic Insights
Received: 10 July 2023. Revised: 30 July 2023. Accepted: 8 August 2023. Available online: 25 September 2023.Geothermal energy, an efficacious and readily available resource, has emerged as a sustainable alternative poised to satisfy escalating global energy demands. This study undertakes a comprehensive analysis of low (heat below 100℃) and medium (heat between 100℃ to 150℃) enthalpy geothermal energy through a bibliometric approach and a literature survey, with an emphasis on the environmental and economic aspects. The methodological procedure encompasses: (i) systematic information processing and configuration, (ii) bibliometric assessment of the evolution and domains of the investigated field, (iii) evaluation of environmental and economic contributions, and (iv) Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis, facilitated by a Focus Group comprising experts from the energy sector. The research on low and medium enthalpy geothermal energy has been identified as an expanding field, with five primary areas of focus: sustainability, cascade systems, heat pumps, numerical modelling, and roundwater potential in geothermal systems. Italy, the United States, and Germany have been recognized as the leading contributors in terms of scientific production. Geothermal energy, from an environmental standpoint, aids the decarbonisation process, reducing reliance on fossil fuels and other renewable energy sources. Although initial investment costs are considerable, the financial recovery period is relatively short. The promotion of geothermal energy, alongside the active involvement of academia, corporations, and governments, bolsters energy and socio-economic development, thereby contributing to the achievement of the Sustainable Development Goals (SDG).This work is supported by ESPOL Polytechnic University research project "Register of geological and mining heritage and its incidence in the defence and preservation of geodiversity in Ecuador" with institutional code CIPAT-01- 2018, and Instituto de Investigación Geológico y Energético (IIGE). We would also like to thank the editorial office for the editorial handling and four anonymous reviewers for their constructive comments and corrections
CP asymmetries in the supersymmetric trilepton signal at the LHC
In the CP-violating Minimal Supersymmetric Standard Model, we study the
production of a neutralino-chargino pair at the LHC. For their decays into
three leptons, we analyze CP asymmetries which are sensitive to the CP phases
of the neutralino and chargino sector. We present analytical formulas for the
entire production and decay process, and identify the CP-violating
contributions in the spin correlation terms. This allows us to define the
optimal CP asymmetries. We present a detailed numerical analysis of the cross
sections, branching ratios, and the CP observables. For light neutralinos,
charginos, and squarks, the asymmetries can reach several 10%. We estimate the
discovery potential for the LHC to observe CP violation in the trilepton
channel.Comment: 39 pages, 8 figures, version to appear in EPJC, discussion(s) added,
typo in (D.79), (D.118) corrected, new Fig. 7; The European Physical Journal
C, Volume 72, Issue 3, 201
Top A_FB at the Tevatron vs. charge asymmetry at the LHC in chiral U(1) flavor models with flavored Higgs doublets
We consider the top forward-backward (FB) asymmetry at the Tevatron and top
charge asymmetry at the LHC within chiral U(1)^\prime models with
flavor-dependent U(1)^\prime charges and flavored Higgs fields, which were
introduced in the ref. [65]. The models could enhance not only the top
forward-backward asymmetry at Tevatron, but also the top charge asymmetry at
LHC, without too large same-sign top pair production rates. We identify
parameter spaces for the U(1)^\prime gauge boson and (pseudo)scalar Higgs
bosons where all the experimental data could be accommodated, including the
case with about 125 GeV Higgs boson, as suggested recently by ATLAS and CMS.Comment: 11 pages, 6 figures, figures and discussion adde
Identification of hepatitis a virus mimotopes by phage display, antigenicity and immunogenicity
A phage-displayed peptide approach was used to identify ligands mimicking antigenic determinants of hepatitis A virus (HAV) for the first time. Bacteriophages displaying HAV mimotopes were isolated from a phage-display peptide library by affinity selection on serum antibodies from hepatitis A patients. Selected phage-peptides were screened for reactivity with sera from HAV infected patients and healthy controls. Four cloned peptides with different sequences were identified as mimotopes of HAV; three of them showed similarity in their amino acid sequences with at least one of the VP3 and VP1 antigenic proteins of HAV. One clone was recognised by 92% of the positive sera. The phagotopes competed effectively with HAV for absorption of anti-HAV-specific antibodies in human sera, as determined by ELISA. The four phage clones induced neutralising anti-HAV antibodies in immunised mice. These results demonstrate the potential of this method to elucidate the disease related epitopes of HAV and to use these mimotopes in diagnostic applications or in the development of a mimotope-based hepatitis A vaccine without the necessity of manipulation of the virus
Top quark forward-backward asymmetry in R-parity violating supersymmetry
The interaction of bottom squark-mediated top quark pair production,
occurring in the R-parity violating minimal supersymmetric standard model
(MSSM), is proposed as an explanation of the anomalously large
forward-backward asymmetry (FBA) observed at the Tevatron. We find that this
model can give a good fit to top quark data, both the inclusive and invariant
mass-dependent asymmetries, while remaining consistent (at the 2-
level) with the total and differential production cross-sections. The scenario
is challenged by strong constraints from atomic parity violation (APV), but we
point out an extra diagram for the effective down quark-Z vertex, involving the
same coupling constant as required for the FBA, which tends to weaken the APV
constraint, and which can nullify it for reasonable values of the top squark
masses and mixing angle. Large contributions to flavor-changing neutral
currents can be avoided if only the third generation of sparticles is light.Comment: 24 pages, 7 figures. v3: included LHC top production cross section
data; model still consistent at 2 sigma leve
Z' signals in polarised top-antitop final states
We study the sensitivity of top-antitop samples produced at all energy stages
of the Large Hadron Collider (LHC) to the nature of an underlying Z' boson, in
presence of full tree level standard model (SM) background effects and relative
interferences. We concentrate on differential mass spectra as well as both
spatial and spin asymmetries thereby demonstrating that exploiting combinations
of these observables will enable one to distinguish between sequential Z's and
those pertaining to Left-Right symmetric models as well as E6 inspired ones,
assuming realistic final state reconstruction efficiencies and error estimates.Comment: 21 pages, 6 colour figures, 10 table
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