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${{\mathit H}^{\pm\pm}}$ (doubly-charged Higgs boson) mass limits

This section covers searches for a doubly-charged Higgs boson with couplings to lepton pairs. Its weak isospin ${{\mathit T}_{{{3}}}}$ is thus restricted to two possibilities depending on lepton chiralities: ${{\mathit T}_{{{3}}}}({{\mathit H}^{\pm\pm}}$) = $\pm{}$1, with the coupling ${{\mathit g}}_{{{\mathit \ell}} {{\mathit \ell}}}$ to ${{\mathit \ell}_{{{L}}}^{-}}{{\mathit \ell}_{{{L}}}^{'-}}$ and ${{\mathit \ell}_{{{R}}}^{+}}{{\mathit \ell}_{{{R}}}^{'+}}$ (``left-handed'') and ${{\mathit T}_{{{3}}}}({{\mathit H}^{\pm\pm}}$) = 0, with the coupling to ${{\mathit \ell}_{{{R}}}^{-}}{{\mathit \ell}_{{{R}}}^{'-}}$ and ${{\mathit \ell}_{{{L}}}^{+}}{{\mathit \ell}_{{{L}}}^{'+}}$ (``right-handed''). These Higgs bosons appear in some left-right symmetric models based on the gauge group SU(2)$_{L}{\times }SU(2)_{R}{\times }$U(1), the type-II seesaw model, and the Zee-Babu model. The two cases are listed separately in the following. Unless noted, one of the lepton flavor combinations is assumed to be dominant in the decay.

Limits for ${{\mathit H}^{\pm\pm}}$ with $\mathit T_{3}$ = $\pm{}$1

VALUE (GeV)

CL%

DOCUMENT ID

TECN

COMMENT

$> 1020$

95

ATLS

${{\mathit \ell}}{{\mathit \ell}}$

$> 220$

95

ATLS

${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$

$> 768$

95

ATLS

${{\mathit e}}{{\mathit e}}$

$> 846$

95

ATLS

${{\mathit \mu}}{{\mathit \mu}}$

$>468$

95

ATLS

${{\mathit e}}{{\mathit \mu}}$

$>400$

95

ATLS

${{\mathit e}}{{\mathit \tau}}$

$>400$

95

ATLS

${{\mathit \mu}}{{\mathit \tau}}$

$> 169$

95

CMS

${{\mathit \tau}}{{\mathit \tau}}$

$> 300$

95

CMS

${{\mathit \mu}}{{\mathit \tau}}$

$> 293$

95

CMS

${{\mathit e}}{{\mathit \tau}}$

$> 395$

95

CMS

${{\mathit \mu}}{{\mathit \mu}}$

$> 391$

95

CMS

${{\mathit e}}{{\mathit \mu}}$

$> 382$

95

CMS

${{\mathit e}}{{\mathit e}}$

$>98.1$

95

DLPH

${{\mathit \tau}}{{\mathit \tau}}$

$>99.0$

95

OPAL

${{\mathit \tau}}{{\mathit \tau}}$

• • We do not use the following data for averages, fits, limits, etc. • •

$>350$

95

ATLS

${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$

$>230$

95

ATLS

${{\mathit H}^{\pm\pm}}{{\mathit H}^{\mp}}$ associated production, ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$, ${{\mathit H}^{\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit Z}}$

CMS

${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$

CMS

${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$

CMS

${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$

$>551$

95

ATLS

${{\mathit e}}{{\mathit e}}$

$>516$

95

ATLS

${{\mathit \mu}}{{\mathit \mu}}$

RVUE

${{\mathit W}^{(*)\pm}}{{\mathit W}^{(*)\pm}}$

CMS

${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$

RVUE

${{\mathit W}^{(*)\pm}}{{\mathit W}^{(*)\pm}}$

$> 330$

95

ATLS

${{\mathit \mu}}{{\mathit \mu}}$

$> 237$

95

ATLS

${{\mathit \mu}}{{\mathit \tau}}$

$> 355$

95

ATLS

${{\mathit \mu}}{{\mathit \mu}}$

$> 398$

95

ATLS

${{\mathit \mu}}{{\mathit \mu}}$

$> 375$

95

ATLS

${{\mathit e}}{{\mathit \mu}}$

$> 409$

95

ATLS

${{\mathit e}}{{\mathit e}}$

$> 128$

95

D0

${{\mathit \tau}}{{\mathit \tau}}$

$> 144$

95

D0

${{\mathit \mu}}{{\mathit \tau}}$

$> 245$

95

CDF

${{\mathit \mu}}{{\mathit \mu}}$

$> 210$

95

CDF

${{\mathit e}}{{\mathit \mu}}$

$> 225$

95

CDF

${{\mathit e}}{{\mathit e}}$

$> 114$

95

CDF

${{\mathit e}}{{\mathit \tau}}$

$> 112$

95

CDF

${{\mathit \mu}}{{\mathit \tau}}$

$> 168$

95

D0

${{\mathit \mu}}{{\mathit \mu}}$

H1

single ${{\mathit H}^{\pm\pm}}$

$> 133$

95

CDF

stable

$>118.4$

95

D0

${{\mathit \mu}}{{\mathit \mu}}$

OPAL

$\mathit E_{{\mathrm {cm}}}{}\leq{}$209 GeV, single ${{\mathit H}^{\pm\pm}}$

SPEC

muonium conversion

THEO

$>45.6$

95

OPAL

$>30.4$

95

OPAL

$\text{none 6.5 - 36.6}$

95

MRK2

¹

AAD 2023AI search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ production using 139 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 13 TeV. Decay branching ratios B( ${{\mathit H}^{++}}$ $\rightarrow$ ${{\mathit \ell}^{+}}{{\mathit \ell}^{'+}}$) for the six flavor combinations are assumed to be equal, adding up to unity. If the T$_{3}$ = 0 states are degenerate with the T$_{3}$ = $\pm1$ states, the limit becomes 1080 GeV.

²

AABOUD 2019K search for pair production of ${{\mathit H}^{++}}{{\mathit H}^{--}}$ followed by the decay ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$ in 36.1 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 13 TeV. The search is interpreted in a doublet-triplet extension of the scalar sector with a vev of 0.1 GeV, leading to B( ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$) = 1. See their Fig. 5 for limits on the cross section for ${\mathit m}_{{{\mathit H}^{++}}}$ between 200 and 700 GeV.

³	See their Figs. 11(b) and 13 for limits with smaller branching ratios.

⁴

AAD 2015AG search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ production in 20.3 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 8 TeV. The limit assumes 100$\%$ branching ratio to the specified final state. See their Fig. 5 for limits for arbitrary branching ratios.

⁵	AAD 2015AP search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ production in 20.3 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 8 TeV. The limit assumes 100$\%$ branching ratio to the specified final state.

⁶

CHATRCHYAN 2012AU search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ production with 4.9 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 7 TeV. The limit assumes 100$\%$ branching ratio to the specified final state. See their Table 6 for limits including associated ${{\mathit H}^{++}}{{\mathit H}^{-}}$ production or assuming different scenarios.

⁷	ABDALLAH 2003 search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ pair production either followed by ${{\mathit H}^{++}}$ $\rightarrow$ ${{\mathit \tau}^{+}}{{\mathit \tau}^{+}}$, or decaying outside the detector.

⁸

ABBIENDI 2002C searches for pair production of ${{\mathit H}^{++}}{{\mathit H}^{--}}$, with ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit \ell}^{\pm}}{{\mathit \ell}^{\pm}}$ (${{\mathit \ell}},{{\mathit \ell}^{\,'}}$ = ${{\mathit e}},{{\mathit \mu}},{{\mathit \tau}}$). The limit holds for ${{\mathit \ell}}={{\mathit \ell}^{\,'}}={{\mathit \tau}}$, and becomes stronger for other combinations of leptonic final states. To ensure the decay within the detector, the limit only applies for $\mathit g({{\mathit H}}{{\mathit \ell}}{{\mathit \ell}}){ {}\gtrsim{} }10^{-7}$.

⁹

AAD 2021U search for pair production of ${{\mathit H}^{++}}{{\mathit H}^{--}}$ followed by the decay ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$ in 139 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 13 TeV. The search is interpreted in a triplet extension of the SM Higgs sector with a triplet vev of 0.1 GeV, leading to B( ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$) = 1. See their Fig. 9(a) for limits on the cross section for ${\mathit m}_{{{\mathit H}^{++}}}$ between 200 and 600 GeV.

¹⁰

AAD 2021U search for associated production of ${{\mathit H}^{\pm\pm}}{{\mathit H}^{\mp}}$ followed by the decays ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$, ${{\mathit H}^{\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit Z}}$ in 139 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 13 TeV. ${{\mathit H}^{\pm\pm}}$ and ${{\mathit H}^{\pm}}$ are assumed to be degenerate in mass within 5 GeV. The search is interpreted in a triplet extension of the SM Higgs sector with a triplet vev of 0.1 GeV, leading to B( ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$) = 1. See their Fig. 9(b) for limits on the cross section for ${\mathit m}_{{{\mathit H}^{++}}}$ between 200 and 600 GeV.

¹¹

SIRUNYAN 2021W search for vector boson fusion production of ${{\mathit H}^{\pm\pm}}$ decaying to ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$ $\rightarrow$ ${{\mathit \ell}^{\pm}}{{\mathit \nu}}{{\mathit \ell}^{\pm}}{{\mathit \nu}}$ in 137 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 13 TeV. See their Fig. 8 for limits on cross section times branching ratio for ${\mathit m}_{{{\mathit H}^{++}}}$ = $0.2 - 3.0$ TeV.

¹²

SIRUNYAN 2019CQ search for ${{\mathit H}^{\pm\pm}}$ production by vector boson fusion followed by the decay ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$ $\rightarrow$ ${{\mathit q}}{{\mathit q}}{{\mathit \ell}}{{\mathit \nu}}$ in 35.9 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 13 TeV. See their Fig. 5 for limits on cross section times branching ratio for ${\mathit m}_{{{\mathit H}^{\pm\pm}}}$ between 0.6 and 2 TeV.

¹³

SIRUNYAN 2018CC search for ${{\mathit H}^{\pm\pm}}$ production by vector boson fusion followed by the decay ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$ in 35.9 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 13 TeV. See their Fig. 3 for limits on cross section times branching ratio for ${\mathit m}_{{{\mathit H}^{\pm\pm}}}$ between 200 and 1000 GeV.

¹⁴

KANEMURA 2015 examine the case where ${{\mathit H}^{++}}$ decays preferentially to ${{\mathit W}^{(*)}}{{\mathit W}^{(*)}}$ and estimate that a lower mass limit of $\sim{}$84 GeV can be derived from the same-sign dilepton data of AAD 2015AG if ${{\mathit H}^{++}}$ decays with 100$\%$ branching ratio to ${{\mathit W}^{(*)}}{{\mathit W}^{(*)}}$.

¹⁵

KHACHATRYAN 2015D search for ${{\mathit H}^{\pm\pm}}$ production by vector boson fusion followed by the decay ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit W}^{\pm}}{{\mathit W}^{\pm}}$ in 19.4 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 8 TeV. See their Fig. 4 for limits on cross section times branching ratio for ${\mathit m}_{{{\mathit H}^{++}}}$ between 160 and 800 GeV.

¹⁶	KANEMURA 2014 examine the case where ${{\mathit H}^{++}}$ decays preferentially to ${{\mathit W}^{()}}{{\mathit W}^{()}}$ and estimate that a lower mass limit of $\sim{}$60 GeV can be derived from the same-sign dilepton data of AAD 2012CY.

¹⁷

AAD 2013Y search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ production in a generic search of events with three charged leptons in 4.6 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 7 TeV. The limit assumes 100$\%$ branching ratio to the specified final state.

¹⁸	AAD 2012AY search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ production with 1.6 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 7 TeV. The limit assumes 100$\%$ branching ratio to the specified final state.

¹⁹

AAD 2012CQ search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ production with 4.7 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 7 TeV. The limit assumes 100$\%$ branching ratio to the specified final state. See their Table 1 for limits assuming smaller branching ratios.

²⁰	ABAZOV 2012A search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ production in 7.0 fb${}^{-1}$ of ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 1.96 TeV.

²¹	AALTONEN 2011AF search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ production in 6.1 fb${}^{-1}$ of ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at $\mathit E_{{\mathrm {cm}}}$ = 1.96 TeV.

²²	AALTONEN 2008AA search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ production in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at $\mathit E_{{\mathrm {cm}}}$= 1.96 TeV. The limit assumes 100$\%$ branching ratio to the specified final state.

²³	ABAZOV 2008V search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ production in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions at $\mathit E_{{\mathrm {cm}}}$= 1.96 TeV. The limit is for B( ${{\mathit H}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \mu}}$) = 1. The limit is updated in ABAZOV 2012A.

²⁴

AKTAS 2006A search for single ${{\mathit H}^{\pm\pm}}$ production in ${{\mathit e}}{{\mathit p}}$ collisions at HERA. Assuming that ${{\mathit H}^{++}}$ only couples to ${{\mathit e}^{+}}{{\mathit \mu}^{+}}$ with $\mathit g_{{{\mathit e}} {{\mathit \mu}}}$ = 0.3 (electromagnetic strength), a limit ${\mathit m}_{{{\mathit H}^{++}}}$ $>$ 141 GeV (95$\%$ CL) is derived. For the case where ${{\mathit H}^{++}}$ couples to ${{\mathit e}}{{\mathit \tau}}$ only the limit is 112 GeV.

²⁵	ACOSTA 2005L search for ${{\mathit H}^{{++}}}{{\mathit H}^{{--}}}$ pair production in ${{\mathit p}}{{\overline{\mathit p}}}$ collisions. The limit is valid for ${{\mathit g}}_{{{\mathit \ell}} {{\mathit \ell}^{\,'}}}$ $<$ $10^{-8}$ so that the Higgs decays outside the detector.

²⁶	ABAZOV 2004E search for ${{\mathit H}^{++}}{{\mathit H}^{--}}$ pair production in ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit \mu}^{\pm}}{{\mathit \mu}^{\pm}}$. The limit is valid for $\mathit g_{{{\mathit \mu}} {{\mathit \mu}}}{ {}\gtrsim{} }$ $10^{-7}$.

²⁷

ABBIENDI 2003Q searches for single ${{\mathit H}^{\pm\pm}}$ via direct production in ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit e}^{\mp}}{{\mathit e}^{\mp}}{{\mathit H}^{\pm\pm}}$, and via ${{\mathit t}}$-channel exchange in ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$. In the direct case, and assuming B( ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit \ell}^{\pm}}{{\mathit \ell}^{\pm}}$) = 1, a 95$\%$ CL limit on ${{\mathit h}}_{ee}$ $<$ 0.071 is set for ${\mathit m}_{{{\mathit H}^{\pm\pm}}}$ $<$ 160 GeV (see Fig. 6). In the second case, indirect limits on ${{\mathit h}}_{ee}$ are set for ${\mathit m}_{{{\mathit H}^{\pm\pm}}}$ $<$ 2 TeV (see Fig. 8).

²⁸

GORDEEV 1997 search for muonium-antimuonium conversion and find $\mathit G_{{{\mathit M}} {{\overline{\mathit M}}}}/\mathit G_{\mathit F}<0.14$ (90$\%~$ CL), where $\mathit G_{{{\mathit M}} {{\overline{\mathit M}}}}$ is the lepton-flavor violating effective four-fermion coupling. This limit may be converted to ${\mathit m}_{{{\mathit H}^{++}}}>210$ GeV if the Yukawa couplings of ${{\mathit H}^{++}}$ to and ${{\mathit \mu}}{{\mathit \mu}}$ are as large as the weak gauge coupling. For similar limits on muonium-antimuonium conversion, see the muon Particle Listings.

²⁹	ASAKA 1995 point out that ${{\mathit H}^{++}}$ decays dominantly to four fermions in a large region of parameter space where the limit of ACTON 1992M from the search of dilepton modes does not apply.

³⁰	ACTON 1992M limit assumes ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit \ell}^{\pm}}{{\mathit \ell}^{\pm}}$ or ${{\mathit H}^{\pm\pm}}$ does not decay in the detector. Thus the region $\mathit g_{{{\mathit \ell}} {{\mathit \ell}}}\approx{}10^{-7}$ is not excluded.

³¹	ACTON 1992M from $\Delta \Gamma _{{{\mathit Z}}}<$40 MeV.

³²

SWARTZ 1990 assume ${{\mathit H}^{\pm\pm}}$ $\rightarrow$ ${{\mathit \ell}^{\pm}}{{\mathit \ell}^{\pm}}$ (any flavor). The limits are valid for the Higgs-lepton coupling g(${{\mathit H}}{{\mathit \ell}}{{\mathit \ell}}$) ${ {}\gtrsim{} }$ $7.4 \times 10^{-7}/[{\mathit m}_{{{\mathit H}}}$/GeV]${}^{1/2}$. The limits improve somewhat for ${{\mathit e}}{{\mathit e}}$ and ${{\mathit \mu}}{{\mathit \mu}}$ decay modes.

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