50 research outputs found
Discovering the composite Higgs through the decay of a heavy fermion
A possible composite nature of the Higgs could be revealed at the early stage
of the LHC, by analyzing the channels where the Higgs is produced from the
decay of a heavy fermion. The Higgs production from a singly-produced heavy
bottom, in particular, proves to be a promising channel. For a value \lambda=3
of the Higgs coupling to a heavy bottom, for example, we find that, considering
a 125 GeV Higgs which decays into a pair of b-quarks, a discovery is possible
at the 8 TeV LHC with 30 fb^{-1} if the heavy bottom is lighter than roughly
530 GeV (while an observation is possible for heavy bottom masses up to 650
GeV). Such a relatively light heavy bottom is realistic in composite Higgs
models of the type considered and, up to now, experimentally allowed. At
\sqrt{s}=14 TeV the LHC sensitivity on the channel increases significantly.
With \lambda=3 a discovery can occur, with 100 fb^{-1}, for heavy bottom masses
up to 1040 GeV. In the case the heavy bottom was as light as 500 GeV, the 14
TeV LHC would be sensitive to the measure of the \lambda\ coupling in basically
the full range \lambda>1 predicted by the theory.Comment: 25 pp. v2: Minor changes. v3: Version accepted for publication in
JHEP. v4: typos fixe
Heavy-light decay topologies as a new strategy to discover a heavy gluon
We study the collider phenomenology of the lightest Kaluza-Klein excitation
of the gluon, G*, in theories with a warped extra dimension. We do so by means
of a two-site effective lagrangian which includes only the lowest-lying spin-1
and spin-1/2 resonances. We point out the importance of the decays of G* to one
SM plus one heavy fermion, that were overlooked in the previous literature. It
turns out that, when kinematically allowed, such heavy-light decays are
powerful channels for discovering the G*. In particular, we present a
parton-level Montecarlo analysis of the final state Wtb that follows from the
decay of G* to one SM top or bottom quark plus its heavy partner. We find that
at \sqrt{s} = 7 TeV and with 10 fb^{-1} of integrated luminosity, the LHC can
discover a KK gluon with mass in the range M_{G*} = (1.8 - 2.2) TeV if its
coupling to a pair of light quarks is g_{G*qqbar} = (0.2-0.5) g_3. The same
process is also competitive for the discovery of the top and bottom partners as
well. We find, for example, that the LHC at \sqrt{s} = 7 TeV can discover a 1
TeV KK bottom quark with an integrated luminosity of (5.3 - 0.61) fb^{-1} for
g_{G*qqbar} = (0.2-0.5) g_3.Comment: 36 pages, 13 figures. v2: a few typos corrected, comments added,
version published in JHE
Anomalous Couplings in Double Higgs Production
The process of gluon-initiated double Higgs production is sensitive to
non-linear interactions of the Higgs boson. In the context of the Standard
Model, studies of this process focused on the extraction of the Higgs trilinear
coupling. In a general parametrization of New Physics effects, however, an even
more interesting interaction that can be tested through this channel is the
(ttbar hh) coupling. This interaction vanishes in the Standard Model and is a
genuine signature of theories in which the Higgs boson emerges from a
strongly-interacting sector. In this paper we perform a model-independent
estimate of the LHC potential to detect anomalous Higgs couplings in
gluon-fusion double Higgs production. We find that while the sensitivity to the
trilinear is poor, the perspectives of measuring the new (ttbar hh) coupling
are rather promising.Comment: 22 pages, 9 figures. v2: plots of Figs.8 and 9 redone to include
experimental uncertainty on the Higgs couplings, references adde
New Higgs Production Mechanism in Composite Higgs Models
Composite Higgs models are only now starting to be probed at the Large Hadron
Collider by Higgs searches. We point out that new resonances, abundant in these
models, can mediate new production mechanisms for the composite Higgs. The new
channels involve the exchange of a massive color octet and single production of
new fermion resonances with subsequent decays into the Higgs and a Standard
Model quark. The sizable cross section and very distinctive kinematics allow
for a very clean extraction of the signal over the background with high
statistical significance. Heavy gluon masses up to 2.8 TeV can be probed with
data collected during 2012 and up to 5 TeV after the energy upgrade to
TeV.Comment: 27 pages, 22 figures. V2: typos corrected, matches published versio
Mass-Matching in Higgsless
Modern extra-dimensional Higgsless scenarios rely on a mass-matching between
fermionic and bosonic KK resonances to evade constraints from precision
electroweak measurements. After analyzing all of the Tevatron and LEP bounds on
these so-called Cured Higgsless scenarios, we study their LHC signatures and
explore how to identify the mass-matching mechanism, the key to their
viability. We find singly and pair produced fermionic resonances show up as
clean signals with 2 or 4 leptons and 2 hard jets, while neutral and charged
bosonic resonances are visible in the dilepton and leptonic WZ channels,
respectively. A measurement of the resonance masses from these channels shows
the matching necessary to achieve . Moreover, a large single
production of KK-fermion resonances is a clear indication of compositeness of
SM quarks. Discovery reach is below 10 fb of luminosity for resonances
in the 700 GeV range.Comment: 28 pages, 18 figure
Strong Double Higgs Production at the LHC
The hierarchy problem and the electroweak data, together, provide a plausible
motivation for considering a light Higgs emerging as a pseudo-Goldstone boson
from a strongly-coupled sector. In that scenario, the rates for Higgs
production and decay differ significantly from those in the Standard Model.
However, one genuine strong coupling signature is the growth with energy of the
scattering amplitudes among the Goldstone bosons, the longitudinally polarized
vector bosons as well as the Higgs boson itself. The rate for double Higgs
production in vector boson fusion is thus enhanced with respect to its
negligible rate in the SM. We study that reaction in pp collisions, where the
production of two Higgs bosons at high pT is associated with the emission of
two forward jets. We concentrate on the decay mode hh -> WW^(*)WW^(*) and study
the semi-leptonic decay chains of the W's with 2, 3 or 4 leptons in the final
states. While the 3 lepton final states are the most relevant and can lead to a
3 sigma signal significance with 300 fb^{-1} collected at a 14 TeV LHC, the two
same-sign lepton final states provide complementary information. We also
comment on the prospects for improving the detectability of double Higgs
production at the foreseen LHC energy and luminosity upgrades.Comment: 54 pages, 26 figures. v2: typos corrected, a few comments and one
table added. Version published in JHE
Composite Higgs Search at the LHC
The Higgs boson production cross-sections and decay rates depend, within the
Standard Model (SM), on a single unknown parameter, the Higgs mass. In
composite Higgs models where the Higgs boson emerges as a pseudo-Goldstone
boson from a strongly-interacting sector, additional parameters control the
Higgs properties which then deviate from the SM ones. These deviations modify
the LEP and Tevatron exclusion bounds and significantly affect the searches for
the Higgs boson at the LHC. In some cases, all the Higgs couplings are reduced,
which results in deterioration of the Higgs searches but the deviations of the
Higgs couplings can also allow for an enhancement of the gluon-fusion
production channel, leading to higher statistical significances. The search in
the H to gamma gamma channel can also be substantially improved due to an
enhancement of the branching fraction for the decay of the Higgs boson into a
pair of photons.Comment: 32 pages, 16 figure
Flavor in Minimal Conformal Technicolor
We construct a complete, realistic, and natural UV completion of minimal
conformal technicolor that explains the origin of quark and lepton masses and
mixing angles. As in "bosonic technicolor", we embed conformal technicolor in a
supersymmetric theory, with supersymmetry broken at a high scale. The exchange
of heavy scalar doublets generates higher-dimension interactions between
technifermions and quarks and leptons that give rise to quark and lepton masses
at the TeV scale. Obtaining a sufficiently large top quark mass requires strong
dynamics at the supersymmetry breaking scale in both the top and technicolor
sectors. This is natural if the theory above the supersymmetry breaking also
has strong conformal dynamics. We present two models in which the strong top
dynamics is realized in different ways. In both models, constraints from
flavor-changing effects can be easily satisfied. The effective theory below the
supersymmetry breaking scale is minimal conformal technicolor with an
additional light technicolor gaugino. We argue that this light gaugino is a
general consequence of conformal technicolor embedded into a supersymmetric
theory. If the gaugino has mass below the TeV scale it will give rise to an
additional pseudo Nambu-Goldstone boson that is observable at the LHC.Comment: 37 pages; references adde
Mutational signatures in esophageal adenocarcinoma define etiologically distinct subgroups with therapeutic relevance
Esophageal adenocarcinoma (EAC) has a poor outcome, and targeted therapy trials have thus far been disappointing owing to a lack of robust stratification methods. Whole-genome sequencing (WGS) analysis of 129 cases demonstrated that this is a heterogeneous cancer dominated by copy number alterations with frequent large-scale rearrangements. Co-amplification of receptor tyrosine kinases (RTKs) and/or downstream mitogenic activation is almost ubiquitous; thus tailored combination RTK inhibitor (RTKi) therapy might be required, as we demonstrate in vitro. However, mutational signatures showed three distinct molecular subtypes with potential therapeutic relevance, which we verified in an independent cohort (n = 87): (i) enrichment for BRCA signature with prevalent defects in the homologous recombination pathway; (ii) dominant T>G mutational pattern associated with a high mutational load and neoantigen burden; and (iii) C>A/T mutational pattern with evidence of an aging imprint. These subtypes could be ascertained using a clinically applicable sequencing strategy (low coverage) as a basis for therapy selection
Authentication and characterisation of a new oesophageal adenocarcinoma cell line: MFD-1.
New biological tools are required to understand the functional significance of genetic events revealed by whole genome sequencing (WGS) studies in oesophageal adenocarcinoma (OAC). The MFD-1 cell line was isolated from a 55-year-old male with OAC without recombinant-DNA transformation. Somatic genetic variations from MFD-1, tumour, normal oesophagus, and leucocytes were analysed with SNP6. WGS was performed in tumour and leucocytes. RNAseq was performed in MFD-1, and two classic OAC cell lines FLO1 and OE33. Transposase-accessible chromatin sequencing (ATAC-seq) was performed in MFD-1, OE33, and non-neoplastic HET1A cells. Functional studies were performed. MFD-1 had a high SNP genotype concordance with matched germline/tumour. Parental tumour and MFD-1 carried four somatically acquired mutations in three recurrent mutated genes in OAC: TP53, ABCB1 and SEMA5A, not present in FLO-1 or OE33. MFD-1 displayed high expression of epithelial and glandular markers and a unique fingerprint of open chromatin. MFD-1 was tumorigenic in SCID mouse and proliferative and invasive in 3D cultures. The clinical utility of whole genome sequencing projects will be delivered using accurate model systems to develop molecular-phenotype therapeutics. We have described the first such system to arise from the oesophageal International Cancer Genome Consortium project.Cancer Research UK, Medical Research CouncilThis is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/srep3241