Prospects for charged Higgs searches at the LHC Akeroyd, A. G.; Aoki, M.; Arhrib, A. ...
The European physical journal. C, Particles and fields,
05/2017, Letnik:
77, Številka:
5
Journal Article
Recenzirano
Odprti dostop
The goal of this report is to summarize the current situation and discuss possible search strategies for charged scalars, in non-supersymmetric extensions of the Standard Model at the LHC. Such ...scalars appear in Multi-Higgs-Doublet models, in particular in the popular Two-Higgs-Doublet model, allowing for charged and additional neutral Higgs bosons. These models have the attractive property that electroweak precision observables are automatically in agreement with the Standard Model at the tree level. For the most popular version of this framework, Model II, a discovery of a charged Higgs boson remains challenging, since the parameter space is becoming very constrained, and the QCD background is very high. We also briefly comment on models with dark matter which constrain the corresponding charged scalars that occur in these models. The stakes of a possible discovery of an extended scalar sector are very high, and these searches should be pursued in all conceivable channels, at the LHC and at future colliders.
COSINUS is a dark matter (DM) direct search experiment that uses sodium iodide (NaI) crystals as cryogenic calorimeters. Thanks to the low nuclear recoil energy threshold and event-by-event ...discrimination capability, COSINUS will address the long-standing DM claim made by the DAMA/LIBRA collaboration. The experiment is currently under construction at the Laboratori Nazionali del Gran Sasso, Italy, and employs a large cylindrical water tank as a passive shield to meet the required background rate. However, muon-induced neutrons can mimic a DM signal therefore requiring an active veto system, which is achieved by instrumenting the water tank with an array of photomultiplier tubes (PMTs). This study optimizes the number, arrangement, and trigger conditions of the PMTs as well as the size of an optically invisible region. The objective was to maximize the muon veto efficiency while minimizing the accidental trigger rate due to the ambient and instrumental background. The final configuration predicts a veto efficiency of 99.63 ± 0.16% and 44.4 ± 5.6% in the tagging of muon events and showers of secondary particles, respectively. The active veto will reduce the cosmogenic neutron background rate to 0.11 ± 0.02 cts
·
kg
-
1
·
year
-
1
,
corresponding to less than one background event in the region of interest for the whole COSINUS-1
π
exposure of 1000 kg
·
days.
The COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) experiment aims at the detection of dark matter-induced recoils in sodium iodide (NaI) crystals ...operated as scintillating cryogenic calorimeters. The detection of both scintillation light and phonons allows performing an event-by-event signal to background discrimination, thus enhancing the sensitivity of the experiment. The choice of using NaI crystals is motivated by the goal of probing the long-standing DAMA/LIBRA results using the same target material. The construction of the experimental facility is foreseen to start by 2021 at the INFN Gran Sasso National Laboratory (LNGS) in Italy. It consists of a cryostat housing the target crystals shielded from the external radioactivity by a water tank acting, at the same time, as an active veto against cosmic ray-induced events. Taking into account both environmental radioactivity and intrinsic contamination of materials used for cryostat, shielding and infrastructure, we performed a careful background budget estimation. The goal is to evaluate the number of events that could mimic or interfere with signal detection while optimising the geometry of the experimental setup. In this paper we present the results of the detailed Monte Carlo simulations we performed, together with the final design of the setup that minimises the residual amount of background particles reaching the detector volume.
The triplet scalars (Δ=Δ++,Δ+,Δ0) utilized in the so-called type-II seesaw model to explain the lightness of neutrinos, would generate nonstandard interactions (NSI) for a neutrino propagating in ...matter. We investigate the prospects to probe these interactions in long baseline neutrino oscillation experiments. We analyze the upper bounds that the proposed DUNE experiment might set on the nonstandard parameters and numerically derive upper bounds, as a function of the lightest neutrino mass, on the ratio the mass MΔ of the triplet scalars, and the strength |λϕ| of the coupling ϕϕΔ of the triplet Δ and conventional Higgs doublet ϕ. We also discuss the possible misinterpretation of these effects as effects arising from a nonunitarity of the neutrino mixing matrix and compare the results with the bounds that arise from the charged lepton flavor violating processes.
The crucial phenomenological and experimental predictions for new physics are outlined, where the number of problems of the Standard Model (neutrino masses and oscillations, dark matter, baryon ...asymmetry of the Universe, strong CP-problem) could find their solutions. The analogies between the cosmological neutrino mass scale from the early universe data and laboratory probes are discussed, as well as the search for new physics and phenomena.
We study inert charged Higgs boson
H
±
production and decays at LHC experiments in the context of constrained scalar dark matter model (CSDMM). In the CSDMM the mass spectrum of the inert doublet and ...singlet scalars is predicted from the GUT scale initial conditions via RGE evolution. We compute the cross sections of processes
pp
→
H
+
H
−
,
H
±
S
i
0
,
where
S
i
0
are neutral scalar particles, at the LHC experiments. We show that for light
H
±
the first process may receive a sizable contribution from the top quark mediated 1-loop diagram with Higgs boson in
s
-channel. In a significant fraction of the parameter space
H
±
are long-lived because their decays to predominantly singlet scalar dark matter (DM) and next-to-lightest (NL) scalar,
H
±
→
S
DM, NL
f f
′, are suppressed by the small singlet-doublet mixing angle and by the moderate mass difference
. The experimentally measurable displaced vertex in
H
±
decays to leptons and/or jets and missing energy allows one to discover the
H
+
H
−
signal over the huge
W
+
W
−
background. If, however,
H
±
are short-lived, the subsequent decays
necessarily produce additional displaced vertices that allow to reconstruct the full
H
±
decay chain. We propose benchmark points for studies of this scenario at the LHC.
The increasing statistical significance of the DAMA/LIBRA annual modulation signal is a cause for tension in the field of dark matter direct detection. The COSINUS experiment aims at a ...model-independent cross-check of the DAMA/LIBRA signal claim, using NaI crystals operated as cryogenic scintillating calorimeters at millikelvin temperatures. Such a setup enables measurement of phonon and scintillation light signals via Transition Edge Sensors (TESs) and allows particle discrimination on an event-by-event basis. The non-standard properties of NaI cause an obstacle when attaching a TES directly onto the surface of the crystal. This can be overcome with the "remoTES" design, where the TES is attached to an external wafer crystal. We present the results from a first successful operation of NaI and other crystals as cryogenic calorimeters with the remoTES design.
We have investigated the production of doubly charged Higgs particles
Δ
L,
R
++ via the
WW fusion process in proton-proton collisions at LHC energies in the framework of the left-right symmetric ...model. The production cross section of the right-triplet Higgs
Δ
R
++ is for representative values of the model parameters at femtobarn level. The discovery reach depends on the mass of the right-handed gauge boson
W
R
. At best
Δ
R
++ masses up to 2.4 TeV are achievable within a one-year run. For
Δ
L
++ the corresponding limit is 1.75 TeV which depends on the value of the left-triplet vev
ν
L
. Comparison with Drell-Yan pair production processes shows that studies of the
WW fusion processes extend the discovery reach of LHC roughly by a factor of two. The main experimental signal of a produced
Δ
L,
R
++ would be a hard same-sign lepton pair. There will be no substantial background due to the Standard Model (SM) interactions, since in the SM a same-sign lepton pair will always be associated with missing energy, i.e. neutrinos, due to lepton number conservation.
We systematically analyze the supersymmetric contributions to the mixing CP asymmetries and branching ratios of
B
→
ϕ
K
S
and
B
→
η
′
K
S
processes. We consider both gluino and chargino exchanges in ...a model independent way by using the mass insertion approximation method. While we adopt the QCD factorization approach for evaluating the corresponding hadronic matrix elements, a critical comparison with predictions in naive factorization one is also provided. We find that pure chargino contributions cannot accommodate the current experimental results on CP asymmetries, mainly due to
b
→
s
γ
constraints. We show that charged Higgs contributions can relax these constraints making chargino responsible for large asymmetries. On the other hand, pure gluino exchanges can easily saturate both the constraints on
B
→
ϕ
K
S
and
B
→
η
′
K
S
CP asymmetries. Moreover, we also find that the simultaneous contributions from gluino and chargino exchanges could easily account for the present experimental results on the mentioned asymmetries. Remarkably, large experimentally allowed enhancements of
B
→
η
′
K
S
branching ratio can easily be achieved by the contribution of two mass insertions in gluino exchanges. Finally, we analyze the correlations between the CP asymmetries of these processes and the direct CP asymmetry in
b
→
s
γ
decay. When all experimental constraints are satisfied, supersymmetry favors large and positive values of
b
→
s
γ
asymmetry.
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