Mounting evidence for a 95 GeV Higgs boson Biekötter, T.; Heinemeyer, S.; Weiglein, G.
The journal of high energy physics,
08/2022, Letnik:
2022, Številka:
8
Journal Article
Recenzirano
Odprti dostop
A
bstract
In 2018 CMS reported an excess in the light Higgs-boson search in the diphoton decay mode at about 95 GeV based on Run 1 and first year Run 2 data. The combined local significance of the ...excess was 2
.
8
σ
. The excess is compatible with the limits obtained in the ATLAS searches from the diphoton search channel. Recently, CMS reported another local excess with a significance of 3
.
1
σ
in the light Higgs-boson search in the di-tau final state, which is compatible with the interpretation of a Higgs boson with a mass of about 95 GeV. We show that the observed results can be interpreted as manifestations of a Higgs boson in the Two-Higgs Doublet Model with an additional real singlet (N2HDM). We find that the lightest Higgs boson of the N2HDM can fit both excesses simultaneously, while the second-lightest state is such that it satisfies the Higgs-boson measurements at 125 GeV, and the full Higgs-boson sector is compatible with all Higgs exclusion bounds from the searches at LEP, the Tevatron and the LHC as well as with other theoretical and experimental constraints. Finally, we demonstrate that it is furthermore possible to accommodate the excesses observed by CMS in the two search channels together with a local 2
.
3
σ
excess in the
b
b
¯
final state observed at LEP in the same mass range.
Recent results reported by the ATLAS and CMS experiments on the search for a SM-like Higgs boson both show an excess for a Higgs mass near 125 GeV, which is mainly driven by the γγ and ZZ⁎ decay ...channels, but also receives some support from channels with a lower mass resolution. We discuss the implications of this possible signal within the context of the minimal supersymmetric Standard Model (MSSM), taking into account previous limits from Higgs searches at LEP, the Tevatron and the LHC. The consequences for the remaining MSSM parameter space are investigated. Under the assumption of a Higgs signal we derive new lower bounds on the tree-level parameters of the MSSM Higgs sector. We also discuss briefly an alternative interpretation of the excess in terms of the heavy CP-even Higgs boson, a scenario which is found to be still viable.
A 96 GeV Higgs boson in the N2HDM Biekötter, T.; Chakraborti, M.; Heinemeyer, S.
The European physical journal. C, Particles and fields,
2020/1, Letnik:
80, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We discuss a
∼
3
σ
signal (local) in the light Higgs-boson search in the diphoton decay mode at
∼
96
GeV
as reported by CMS, together with a
∼
2
σ
excess (local) in the
b
b
¯
final state at LEP in ...the same mass range. We interpret this possible signal as a Higgs boson in the 2 Higgs Doublet Model with an additional real Higgs singlet (N2HDM). We find that the lightest Higgs boson of the N2HDM can perfectly fit both excesses simultaneously, while the second lightest state is in full agreement with the Higgs-boson measurements at
125
GeV
, and the full Higgs-boson sector is in agreement with all Higgs exclusion bounds from LEP, the Tevatron and the LHC as well as other theoretical and experimental constraints. We show that only the N2HDM type II and IV can fit both the LEP excess and the CMS excess with a large ggF production component at
∼
96
GeV
. We derive bounds on the N2HDM Higgs sector from a fit to both excesses and describe how this signal can be further analyzed at the LHC and at future
e
+
e
-
colliders, such as the ILC.
The CDF collaboration recently reported a measurement of the
W
-boson mass
M
W
whose value shows a large upward deviation from the Standard Model (SM) prediction. The question arises whether such ...large values of
M
W
could be accommodated in extensions of the SM without violating other constraints and which phenomenological consequences this would have. A different type of deviation from the SM has been observed experimentally in the searches for light Higgs bosons. CMS has observed two excesses with a local significance of about
3
σ
in the
γ
γ
and
τ
+
τ
-
final states for a hypothetical Higgs-boson mass of approximately 95 GeV. These two excesses are compatible with the corresponding ATLAS limits. Earlier an excess was also observed in the Higgs-boson searches at LEP in the
b
b
¯
final state at the local
2
σ
confidence level at about the same mass. It was shown recently that the three excesses can be accommodated in a Two-Higgs-Doublet Model that is extended with a real singlet (N2HDM) of Yukawa type IV, while being in agreement with all other theoretical and experimental constraints. We demonstrate here that the region of the parameter space that describes the three excesses can also give rise to a large contribution to
M
W
in agreement with the recent CDF measurement. We discuss further phenomenological consequences of this scenario.
For the interpretation of the signal discovered in the Higgs searches at the LHC it will be crucial in particular to discriminate between the minimal Higgs sector realized in the standard model (SM) ...and its most commonly studied extension, the minimal supersymmetric standard model (MSSM). The measured mass value, having already reached the level of a precision observable with an experimental accuracy of about 500 MeV, plays an important role in this context. In the MSSM the mass of the light CP-even Higgs boson, Mh, can directly be predicted from the other parameters of the model. The accuracy of this prediction should at least match the one of the experimental result. The relatively high mass value of about 126 GeV has led to many investigations where the scalar top quarks are in the multi-TeV range. We improve the prediction for Mh in the MSSM by combining the existing fixed-order result, comprising the full one-loop and leading and subleading two-loop corrections, with a resummation of the leading and subleading logarithmic contributions from the scalar top sector to all orders. In this way for the first time a high-precision prediction for the mass of the light CP-even Higgs boson in the MSSM is possible all the way up to the multi-TeV region of the relevant supersymmetric particles. The results are included in the code FEYNHIGGS.
An important task at future colliders is the measurement of the triple Higgs coupling. Depending on its size relative to the Standard Model (SM) value, certain collider options result in a higher ...experimental accuracy. Within the framework of Two Higgs Doublet Models (2HDM) types I and II we investigate the allowed ranges for all triple Higgs couplings involving at least one light, SM-like Higgs boson. We take into account theoretical constraints (unitarity, stability), experimental constraints from direct Higgs-boson searches, measurements of the SM-like Higgs-boson properties, flavor observables and electroweak precision data. We find that the SM-type triple Higgs coupling w.r.t. its SM value,
λ
hhh
/
λ
SM
, can range between
∼
-
0.5
and
∼
1.5
. Depending on which value is realized, the HL-LHC can compete with, or is clearly inferior to the ILC. We find the coupling
λ
hhH
between
∼
-
1.5
and
∼
1.5
. Triple Higgs couplings involving two heavy Higgs bosons,
λ
hHH
,
λ
hAA
and
λ
h
H
+
H
-
can reach values up to
O
(
10
)
, roughly independent of the 2HDM type. This can lead to potentially strongly enhanced production of two Higgs-bosons at the HL-LHC or high-energy
e
+
e
-
colliders.
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.
The measurement of the triple Higgs coupling is one of the main tasks of the (HL-)LHC and future lepton colliders. Similarly, triple Higgs couplings involving BSM Higgs bosons are of high interest. ...Within the framework of Two Higgs Doublet Models (2HDM) we investigate the allowed ranges for all triple Higgs couplings involving at least one light, SM-like Higgs boson. We present newly the allowed ranges for 2HDM type III and IV and update the results within the type I and II. We take into account theoretical constraints from unitarity and stability, experimental constraints from direct BSM Higgs-boson searches, measurements of the rates of the SM-like Higgs-boson at the LHC, as well as flavor observables and electroweak precision data. For the SM-type triple Higgs coupling w.r.t. its SM value,
λ
hhh
/
λ
SM
, we find allowed intervals of
∼
-
0.5
,
1.3
in type I and
∼
0.5
,
1.0
in the other Yukawa types. These allowed ranges have important implications for the experimental determination of this coupling at future collider experiments. We find the coupling
λ
hhH
between
∼
-
1.5
and
∼
+
1.5
in the four Yukawa types. For the triple Higgs couplings involving two heavy neutral Higgs bosons,
λ
hHH
and
λ
hAA
we find values between
∼
-
0.5
and
∼
16
, and between
∼
-
1
and
∼
32
for
λ
h
H
+
H
-
. These potentially large values could lead to strongly enhanced production of two Higgs-bosons at the HL-LHC or high-energy lepton colliders.
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