In several searches for additional Higgs bosons at the LHC, in particular in a CMS search exploring decays to pairs of top quarks,
t
t
¯
, and in an ATLAS search studying tau leptons,
τ
+
τ
-
, local ...excesses of about
3
σ
standard deviations or above have been observed at a mass scale of approximately
400
GeV
. We investigate to what extent a possible signal in these channels could be accommodated in the Next-to-Two-Higgs-Doublet Model (N2HDM) or the Next-to Minimal Supersymmetric Standard Model (NMSSM). In a second step we analyze whether such a model could be compatible with both a signal at around
400
GeV
and
96
GeV
, where the latter possibility is motivated by observed excesses in searches for the
b
b
¯
final state at LEP and the di-photon final state at CMS. The analysis for the N2HDM reveals that the observed excesses at
400
GeV
in the
t
t
¯
and
τ
+
τ
-
channels point towards different regions of the parameter space, while one such excess and an additional Higgs boson at around
96
GeV
could simultaneously be accommodated. In the context of the NMSSM an experimental confirmation of a signal in the
t
t
¯
final state would favour the alignment-without-decoupling limit of the model, where the Higgs boson at
125
GeV
could be essentially indistinguishable from the Higgs boson of the standard model. In contrast, a signal in the
τ
+
τ
-
channel can only be accommodated outside of this limit, and parts of the investigated parameter space could be probed with Higgs signal-rate measurements at the (HL-)LHC.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Novel considerations are presented on the physics, apparatus and accelerator designs for a future, luminous, energy frontier electron-hadron (
eh
) scattering experiment at the LHC in the thirties ...for which key physics topics and their relation to the hadron-hadron HL-LHC physics programme are discussed. Demands are derived set by these physics topics on the design of the LHeC detector, a corresponding update of which is described. Optimisations on the accelerator design, especially the interaction region (IR), are presented. Initial accelerator considerations indicate that a common IR is possible to be built which alternately could serve
eh
and
hh
collisions while other experiments would stay on
hh
in either condition. A forward-backward symmetrised option of the LHeC detector is sketched which would permit extending the LHeC physics programme to also include aspects of hadron-hadron physics. The vision of a joint
eh
and
hh
physics experiment is shown to open new prospects for solving fundamental problems of high energy heavy-ion physics including the partonic structure of nuclei and the emergence of hydrodynamics in quantum field theory while the genuine TeV scale DIS physics is of unprecedented rank.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In high energy physics (HEP) event simulations, petabytes of data are processed and stored requiring millions of CPU-years. This enormous demand for computing resources is handled by centers ...distributed worldwide, which form part of the LHC computing grid. The consumption of such an important amount of resources demands for an efficient production of simulation and for the early detection of potential errors. In this article we present a new monitoring framework for grid environments, which polls a measure of data quality during job execution. This online monitoring facilitates the early detection of configuration errors (specially in simulation parameters), and may thus contribute to significant savings in computing resources.
Strangephilic Higgs bosons in the MSSM Lee, J. S.; Peters, Y.; Pilaftsis, A. ...
The European physical journal. C, Particles and fields,
03/2010, Letnik:
66, Številka:
1-2
Journal Article
Recenzirano
Odprti dostop
We suggest a new CPX-derived scenario for the search for
strangephilic
MSSM Higgs bosons at the Tevatron and the LHC, in which all neutral and charged Higgs bosons decay predominantly into pairs of ...strange quarks and into a strange and a charm quark, respectively. The proposed scenario is realized within a particular region of the MSSM parameter space and requires large values of tan
β
, where threshold radiative corrections are significant to render the effective strange-quark Yukawa coupling dominant. Experimental searches for neutral Higgs bosons based on the identification of
b
-quark jets or
τ
leptons may miss a strangephilic Higgs boson and its existence could be inferred indirectly by searching for hadronically decaying charged Higgs bosons. Potential strategies and experimental challenges to search for strangephilic Higgs bosons at the Tevatron and the LHC are discussed.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We review CP-violating effects in \(Z \rightarrow 3\) jet and \(Z \rightarrow\) 4 jet decays, assuming the presence of CP-violating effective \(Z b \bar{b} G\) and \(Z b \bar{b} G G\) couplings. ...Longitudinal beam polarization is included in the studies. We propose a direct search for such CP-violating couplings by using various CP-odd observables. The data of a future linear collider running at the Z-resonance in the so-called GigaZ option should give significant information on the couplings. Finally we show that stringent bounds on the mass of excited b quarks can be derived if appropriate couplings are of a size characteristic of a strong interaction.
We analyse CP-violating effects in Z \(\rightarrow\) 4 jet decays, assuming the presence of a CP-violating effective triple gluon coupling. We discuss the influence of this coupling on the decay ...width. Furthermore, we analyse different CP-odd observables and propose strategies of a direct search for such a CP-violating GGG coupling. The present data of LEP 1 should give significant information on the coupling.
We analyse CP-violating effects in Z \(\rightarrow\) 4 jet decays, assuming the presence of CP-violating effective \(Z b \bar{b} G\)$ and \(Z b \bar{b} G G\) couplings. We discuss the influence of ...these couplings on the decay width. Furthermore, we propose various strategies of a direct search for such CP-violating couplings by using different CP-odd observables. The present data of LEP 1 should give significant information on the couplings.
The 5th International Workshop on Top Quark Physics (TOP 2012) took place in Winchester, UK, from the 16–21 September. It gathered students as well as people active in the top quark sector and ...provided a framework to highlight the newest results and matters related to top quark physics. Discovered in 1995, the top quark is the sixth and heaviest of all quarks, and it is the only one with a lifetime short enough to be observed 'naked'. This makes it an important testing ground in the search for new physics. In fact, the fact of its mass being so much larger than the other quarks, hints at its special role in the Higgs mechanism. For the same reason, in many models of New Physics, new heavy resonances are expected to couple mostly with top quarks. Even if no new particles are observed, the direct correlation between its angular momentum and that of its detectable decay products allows us to probe indirectly New Physics in action when top quarks are created. In this edition of the TOP conference series, for the first time, the agenda was equally balanced between 'traditional' measurements and the now vast number of searches for physics BSM in the top quark sector, thanks mostly to the amount of data collected at the LHC in its Run I. New results were presented by both the Tevatron and the LHC collaborations: improved ttbar and single top cross-section measurements, refined techniques to measure the top quark mass and a large number of results on properties such as spin correlation and W boson polarization in top quark decays were shown. More technical discussions on the experimental issues, both from the detector and the simulation side also took place, drawing together experimentalists and theorists. Reviews of the latest results on ttbar asymmetry both from CDF and D0 and from ATLAS and CMS were shown, and theorists active in the field made some interesting points on this hot topic. Additionally, results on the search for fourth generation fermions and new resonances in the boosted top regime were also provided. Finally, a set of dedicated talks on the interplay between the top sector and other hot subjects, like the Higgs and SUSY, were given both at the theory and experimental level. Furthermore, ad hoc student sessions were organized to allow younger colleagues to pose questions to the senior experts in the field and contribute with their more recent studies. The conference has been a definitive success, not just scientifically: about 130 participants from all over the world created a collegiate spirit which culminated in the social events at Winchester Hall below King Arthur's table; and in a cosy 16th century barn for the social dinner. The Local Organizing Committee would like to thank all participants, and in particular the speakers, for their high level contributions to TOP 2012 and for making this a very fruitful and pleasant time together. We conclude by wishing the Organizing Committee of TOP 2013 all the best for a successful conference. We look forward to seeing everyone in Germany in 2013. Giuseppe Salamanna Local Organizing Committee London, June 2013 Local Organising Committee Veronique Boisvert (Chair, Royal Holloway, University of London) Lucio Cerrito (Queen Mary, University of London) Akram Khan (Brunel University, London) Stefano Moretti (University of Southampton) Mark Owen (University of Manchester) Giuseppe Salamanna (Queen Mary, University of London) Christian Schwanenberger (University of Manchester) International Advisory Committee Roberto Tenchini (INFN, Pisa) Martine Bosman (IFAE, Barcelona) Michelangelo Mangano (CERN) Scott Willenbrock (University of Illinois, Urbana) Werner Bernreuther (RWTH, Aachen) Jorgen D'Hondt (VUB, Brussels) Antonio Onofre (LIP, University Minho) Fabio Maltoni (UCL, Louvain) Eric Laenen (NIKHEF) Fabrizio Margaroli (INFN, Roma 1) Juan Antonio Aguilar Saavedra (University of Granada) Yvonne Peters (University of Manchester) Roberto Chierici (CERN) Markus Cristinziani (University of Bonn)
W bosons can be produced in the channels \(e^\pm p\to W^\pm + X\) at HERA thus allowing to probe for anomalous trilinear couplings among the gauge bosons. We discuss the next-to-leading order (NLO) ...QCD corrections to the photoproduction of W bosons with finite transverse momentum at HERA. The higher-order QCD corrections reduce the factorization scale dependence significantly and modify the leading-order (LO) cross sections by \(\pm {\cal O}(10\%)\).
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