374 research outputs found
The Diboson Excess: Experimental Situation and Classification of Explanations; A Les Houches Pre-Proceeding
We examine the `diboson' excess at TeV seen by the LHC experiments
in various channels. We provide a comparison of the excess significances as a
function of the mass of the tentative resonance and give the signal cross
sections needed to explain the excesses. We also present a survey of available
theoretical explanations of the resonance, classified in three main approaches.
Beyond that, we discuss methods to verify the anomaly, determining the major
properties of the various surpluses and exploring how different models can be
discriminated. Finally, we give a tabular summary of the numerous explanations,
presenting their main phenomenological features.Comment: 37 pages, 9 Figures, 1 Tabl
Symmetry Restored in Dibosons at the LHC?
A number of LHC resonance search channels display an excess in the invariant
mass region of 1.8 - 2.0 TeV. Among them is a excess in the fully
hadronic decay of a pair of Standard Model electroweak gauge bosons, in
addition to potential signals in the and dijet final states. We perform a
model-independent cross-section fit to the results of all ATLAS and CMS
searches sensitive to these final states. We then interpret these results in
the context of the Left-Right Symmetric Model, based on the extended gauge
group , and show that a heavy right-handed
gauge boson can naturally explain the current measurements with just a
single coupling . In addition, we discuss a possible connection
to dark matter.Comment: 25 pages, 12 figures, V2: references added, extended discussion of
Minimal Left-Right Dark Matter, small correction to decay width - conclusions
unchanged, V3: expanded discussion of input parameters and statistical
procedure, V4: matches published versio
Diboson Excesses Demystified in Effective Field Theory Approach
We study the collider implication of a neutral resonance which decays to
several diboson final states such as , , and via a
minimal set of effective operators. We consider both CP-even and CP-odd bosonic
states with spin 0, 1, or 2. The production cross sections for the bosonic
resonance states are obtained with the effective operators involving gluons
(and quarks), and the branching fractions are obtained with the operators
responsible for the interactions with electroweak gauge bosons. We demonstrate
that each scenario allows for a broad parameter space which could accommodate
the recently-reported intriguing excesses in the ATLAS diboson final states,
and discuss how the CP states and spin information of the resonance can be
extracted at the LHC run II.Comment: 22 pages, 6 figures, main text slightly modified with results
unchange
Reconciling the 2 TeV Excesses at the LHC in a Linear Seesaw Left-Right Model
We interpret the 2 TeV excesses at the LHC in a left-right symmetric model
with Higgs doublets and spontaneous -parity violation. The light neutrino
masses are understood via a linear seesaw, suppressed by a high -parity
breaking scale, and the heavy neutrinos have a pseudo-Dirac character. In
addition, with a suppressed right-handed gauge coupling
in an embedding, we can thereby interpret the observed excess
at CMS. We show that it can be reconciled with the diboson and dijet excesses
within a simplified scenario based on our model. Moreover, we find that the
mixing between the light and heavy neutrinos can be potentially large which
would induce dominant non-standard contributions to neutrinoless double beta
decay via long-range and neutrino exchange.Comment: References added, typos fixed, matches published version, 12 pages, 4
figure
Interpretations of the ATLAS Diboson Anomaly
Recently, the ATLAS Collaboration recorded an interesting anomaly in diboson
production with excesses at the diboson invariant mass around 2 TeV in boosted
jets of all the , , and channels. We offer a theoretical
interpretation of the anomaly using a phenomenological right-handed model with
extra and bosons. Constraints from narrow total decay widths, dijet
cross sections, and production are taken into account. We also
comment on a few other possibilities.Comment: v4: match the published version; v3: 18 pages, 6 figures, change to
leptophobic Z' model to take into account the EW constraints, and some
updates to the analysis and text; v2: 17 pages, 7 figures; a new section and
a new figure are added; correct the statement about the WH; references are
also adde
Stealth multiboson signals
We introduce the `stealth bosons' , light boosted particles with a decay
into two daughter bosons , which
subsequently decay into four quarks that are reconstructed as a single fat jet.
Variables that measure the two-pronged structure of fat jets, which are used
for diboson resonance searches in hadronic or semi-leptonic final states,
classify the jets produced in stealth boson decays as QCD-like - actually, for
these variables they may seem more background-like than the QCD background
itself. The number of tracks in those jets can also be, on average, much higher
than for the fat jets arising from the hadronic decay of boosted and
bosons. Therefore, these elusive particles are hard to spot in standard
searches. Heavy resonances decaying into two such stealth bosons, or one plus a
boson, could offer an explanation for the recurrent small excesses found
in hadronic diboson resonance searches near an invariant mass of 2 TeV.Comment: LaTeX 32 pages. v2: three appendices added as well as many additional
discussions, journal versio
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