pdgLive

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit V}}{{\mathit V}}$ $/$ ${{\mathit \ell}}{{\mathit \ell}}$ $/$ ${{\mathit \ell}}{{\mathit \nu}}$, ${{\mathit V}}$ = ${{\mathit W}},{{\mathit Z}},{{\mathit h}}$

²¹

AABOUD

ATLS

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \mu}}$ $/$ ${{\mathit e}}{{\mathit \tau}}$ $/$ ${{\mathit \mu}}{{\mathit \tau}}$

²²

AAIJ

LHCB

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit A}^{\,'}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$; dark photon

²³

BANERJEE

NA64

${{\mathit e}}$ ${{\mathit Z}}$ $\rightarrow$ ${{\mathit e}}{{\mathit Z}}{{\mathit X}}$( ${{\mathit A}^{\,'}}$)

²⁴

BANERJEE

NA64

${{\mathit e}}$ ${{\mathit Z}}$ $\rightarrow$ ${{\mathit e}}{{\mathit Z}}{{\mathit A}^{\,'}}$, ${{\mathit A}^{\,'}}$ $\rightarrow$ ${{\mathit \chi}}{{\mathit \chi}}$

²⁵

MARSICANO

E137

${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit A}^{\,'}}$( ${{\mathit \gamma}}$) visible decay

²⁶

SIRUNYAN

CMS

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit Z}^{\,'}}$ $\rightarrow$ ${{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ at 13 TeV

²⁷

SIRUNYAN

CMS

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ Black Hole, string ball, sphaleron

²⁸

SIRUNYAN

CMS

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit j}}{{\mathit j}}$

²⁹

SIRUNYAN

CMS

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \mu}}{{\overline{\mathit \mu}}}$

³⁰

SIRUNYAN

CMS

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$

³¹

SIRUNYAN

CMS

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit V}}$ $\rightarrow$ ${{\mathit W}}{{\mathit h}}$; ${{\mathit h}}$ $\rightarrow$ ${{\mathit b}}{{\overline{\mathit b}}}$; ${{\mathit W}}$ $\rightarrow$ ${{\mathit \ell}}{{\mathit \nu}}$

³²

AABOUD

ATLS

${{\mathit W}}{{\mathit H}}$, ${{\mathit Z}}{{\mathit H}}$ resonance

³³

AAIJ

LHCB

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \pi}_{{{v}}}}{{\mathit \pi}_{{{v}}}}$, ${{\mathit \pi}_{{{v}}}}$ $\rightarrow$ ${{\mathit j}}{{\mathit j}}$

³⁴

AAD

ATLS

${{\mathit \ell}}$ + (${{\mathit \ell}}$s or jets)

³⁵

AAD

ATLS

${{\mathit W}}{{\mathit W}}$ , ${{\mathit W}}{{\mathit Z}}$ , ${{\mathit Z}}{{\mathit Z}}$ resonance

³⁶

KRASZNAHORKAY

${{\mathit p}}$ ${}^{7}\mathrm {Li}$ $\rightarrow$ ${}^{8}\mathrm {Be}$ $\rightarrow$ ${{\mathit X}{(17)}}{{\mathit N}}$ , ${{\mathit X}{(17)}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$

³⁷

LEES

BABR

${{\mathit e}^{+}}{{\mathit e}^{-}}$ collisions

³⁸

ADAMS

KTEV

$\mathit m$= $1.2 - 5$ GeV

$<10^{-36} - 10^{-33}$

³⁹

GALLAS

TOF

$\mathit m$= $0.5 - 20$ GeV

$<(4 - 0.3){\times }\text{ 10}$$^{-31}$

⁴⁰

AKESSON

CNTR

$\mathit m$ = $0 - 5$ GeV

$<2 \times 10^{-36}$

⁴¹

BADIER

BDMP

$\tau $ = (0.05$-1.){\times }10^{-8}$s

$<2.5 \times 10^{-35}$

⁴²

GUSTAFSON

CNTR

$\tau $ $>10^{-7}$ s

AAD 2024AE search for heavy vector triplet production with decay to boson pairs. No signal was observed. Limits placed in ${{\mathit \sigma}}$ vs m plane. Limits also placed in various two-dimensional coupling planes (${{\mathit g}_{{{F}}}}$, ${{\mathit g}_{{{H}}}}$, ${{\mathit g}_{{{{{\mathit \ell}}}}}}$, ${{\mathit g}_{{{{{\mathit \ell}}}}}}$(3rd Gen), ${{\mathit g}_{{{q}}}}$, ${{\mathit g}_{{{q}}}}$(3rd Gen), ${{\mathit g}_{{{q}}}}$(1st/2nd Gen)).

²	AAD 2024BV search for VBF di-Higgs production with decay to boosted 4${{\mathit b}}$ state. No signal observed. Limits placed in mass vs. cross section plane for various simplified models.

³	AAD 2024CD search for hadronically-decaying ${{\mathit W}}$ $/$ ${{\mathit Z}}$ + MET events from new physics with 140 fb${}^{-1}$ at 13 TeV. No signal observed. Limits placed on various simplified new physics models.

⁴	AAD 2024E uses a new resonance search technique for two-body decays into any pair of ${{\mathit \ell}}$, ${{\mathit b}}$, and jet with 140 fb${}^{-1}$ of data. No signal was observed. Limits placed in ${{\mathit \sigma}}$ vs mass plane for various decay modes.

⁵	AAD 2024S search for quantum black hole (QBH) decay to lepton + jet in 140 fb${}^{-1}$ of data. No signal observed. Limits placed in ${{\mathit \sigma}}\cdot{}$BF vs mass plane for ADD and RS models.

⁶	HAYRAPETYAN 2024AB search for heavy neutral leptons ${{\mathit N}}$ at CMS with 138 fb${}^{-1}$ of data. No signal observed. Limits placed in mixing angle vs m(${{\mathit N}}$) plane.

⁷	HAYRAPETYAN 2024AC search for heavy long-lived neutrino ${{\mathit N}}$ produced in ${{\mathit B}}$-decays in 41.6 fb${}^{-1}$ of data. No signal observed. Limits placed in mixing angle vs m(${{\mathit N}}$) plane.

⁸	HAYRAPETYAN 2024AZ search for various new bosons via production and decay to four muon states with 41.5 and 59.7 fb${}^{-1}$ of data at 13 TeV. No signal observed. Limits placed usually in mass vs. cross section plane for a variety of new physics simplified models.

⁹	AAD 2023P search in 22 channels for exotica produced in association with ${{\mathit h}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$ in 139 fb${}^{-1}$ of data. No signal observed. Limits placed on production cross section in various channels.

¹⁰	TUMASYAN 2023BC search for ${{\mathit \gamma}}$-jet resonance at CMS with 138 fb${}^{-1}$ of data. No signal observed. Limits placed on quantum black hole and excited quark models.

¹¹

TUMASYAN 2023BF search for ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}{{\mathit p}}{+}$ ${{\mathit \gamma}}$ $/$ ${{\mathit Z}}{+}$ ${{\mathit X}}$ search where ${{\mathit X}}$ is missing particle using CMS-TOTEM with 37.2 fb${}^{-1}$ of data. No signal observed. Limits placed on ${{\mathit \sigma}}$ vs. m plane.

¹²	TUMASYAN 2022AG search for strongly interacting neutral massive particles via trackless jets with 16.1 fb${}^{-1}$ at 13 TeV; no signal detected; limits placed in mass vs. cross section plane for various simplified models.

¹³	AAD 2021F search for hard monojet production at ATLAS with 139 ${}^{-1}$ of 13 TeV data. No signal observed. Limits placed on invisible production cross-section recoiling against ISR and interpreted in variety of BSM models.

¹⁴	AAIJ 2020AL search for dimuon resonance from promptly decaying ${{\mathit X}}$ particle. No signal detected. Limits placed on m(${{\mathit X}}$) up to 60 GeV depending on mixing in 2HDM.

¹⁵

SIRUNYAN 2020AY measured ${{\mathit \Upsilon}}$(1S) pair production cross section and searched for new states decaying into ${{\mathit \Upsilon}{(1S)}}{{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$ at CMS with 13 TeV with 35.9 fb${}^{-1}$. No signal is found and limits are set in ${{\mathit \sigma}}\cdot{}$BF vs. mass plane for tetra-${{\mathit b}}$-quarks with masses between 17.5 and 19 GeV and for generic search for narrow resonances with mass between 16.5 and 27 GeV.

¹⁶	SIRUNYAN 2020Z search for BSM physics via multilepton production with CMS at 13 TeV with 137 fb${}^{-1}$; no signal is found and limits are set on type-III seesaw and other BSM models.

¹⁷	AABOUD 2019H searches for di-photon-jet resonance at 13 TeV and 36.7 fb${}^{-1}$ of data; no signal found and limits placed on ${{\mathit \sigma}}\cdot{}$BR vs. mass plane for various simplified models.

¹⁸	AABOUD 2019V review ATLAS searches for mediator-based DM at 7, 8, and 13 TeV with up to 37 fb${}^{-1}$ of data; no signal found and limits set for wide variety of simplified models of dark matter.

¹⁹	SIRUNYAN 2019O search for ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \gamma}}$ $\not E_T$ at 13 TeV with 36.1 fb${}^{-1}$; no signal found and limits set for various simplified models.

²⁰

AABOUD 2018CJ make multichannel search for ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit V}}{{\mathit V}}$ $/$ ${{\mathit \ell}}{{\mathit \ell}}$ $/$ ${{\mathit \ell}}{{\mathit \nu}}$, ${{\mathit V}}$ = ${{\mathit W}},{{\mathit Z}},{{\mathit h}}$ at 13 TeV, 36.1 fb${}^{-1}$; no signal found; limits placed for several BSM models.

²¹

AABOUD 2018CM search for lepton-flavor violating resonance in ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \mu}}$ $/$ ${{\mathit e}}{{\mathit \tau}}$ $/$ ${{\mathit \mu}}{{\mathit \tau}}$ at 13 TeV, 36.1 fb${}^{-1}$; no signal is found and limits placed for various BSM models.

²²	AAIJ 2018AJ search for prompt and delayed dark photon decay ${{\mathit A}^{\,'}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$ at LHCb detector using 1.6 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at 13 TeV; limits on m(${{\mathit A}^{\,'}}$) vs. kinetic mixing are set.

²³

BANERJEE 2018 search for dark photon ${{\mathit A}^{\,'}}$/16.7 MeV boson ${{\mathit X}}$ at NA64 via ${{\mathit e}}$ ${{\mathit Z}}$ $\rightarrow$ ${{\mathit e}}{{\mathit Z}}{{\mathit X}}$( ${{\mathit A}^{\,'}}$); no signal found and limits set on the ${{\mathit X}}-{{\mathit e}^{-}}$ coupling ${{\mathit \epsilon}_{{{e}}}}$ in the range $1.3 \times 10^{-4}{}\leq{}{{\mathit \epsilon}_{{{e}}}}{}\leq{}4.2 \times 10^{-4}$ excluding part of the allowed parameter space.

²⁴	BANERJEE 2018A search for invisibly decaying dark photons in ${{\mathit e}}$ ${{\mathit Z}}$ $\rightarrow$ ${{\mathit e}}{{\mathit Z}}{{\mathit A}^{\,'}}$, ${{\mathit A}^{\,'}}$ $\rightarrow$invisible; no signal found and limits set on mixing for m(${{\mathit A}^{\,'}}$) $<$ 1 GeV.

²⁵

MARSICANO 2018 search for dark photon ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit A}^{\,'}}$( ${{\mathit \gamma}}$) visible decay in SLAC E137 ${{\mathit e}}$ beam dump data. No signal observed and limits set in ${{\mathit \epsilon}}$ coupling vs m(${{\mathit A}^{\,'}}$) plane, see their figure 7.

²⁶	SIRUNYAN 2018BB search for high mass dilepton resonance; no signal found and exclude portions of p-space of ${{\mathit Z}^{\,'}}$, KK graviton models.

²⁷	SIRUNYAN 2018DA search for ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ Black Hole, string ball, sphaleron via high multiplicity events at 13 TeV, 35.9 fb${}^{-1}$; no signal, require e.g. m(BH) $>$ 10.1 TeV.

²⁸	SIRUNYAN 2018DD search for ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit j}}{{\mathit j}}$ deviations in dijet angular distribution. No signal observed. Set limits on large extra dimensions, black holes and DM mediators e.g. m(BH) $>$ $5.9 - 8.2$ TeV.

²⁹	SIRUNYAN 2018DR search for dimuon resonance in ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit b}}{{\mathit \mu}}{{\overline{\mathit \mu}}}$ at 8 and 13 TeV. Slight excess seen at m(${{\mathit \mu}}{{\overline{\mathit \mu}}}$) $\sim{}$ 28 GeV in some channels.

³⁰	SIRUNYAN 2018DU search for high mass diphoton resonance in ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$ at 13 TeV using 35.9 fb${}^{-1}$; no signal; limits placed on RS Graviton, LED, and clockwork.

³¹

SIRUNYAN 2018ED search for ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit V}}$ $\rightarrow$ ${{\mathit W}}{{\mathit h}}$; ${{\mathit h}}$ $\rightarrow$ ${{\mathit b}}{{\overline{\mathit b}}}$; ${{\mathit W}}$ $\rightarrow$ ${{\mathit \ell}}{{\mathit \nu}}$ at 13 TeV with 35.9 fb${}^{-1}$; no signal; limits set on m(${{\mathit W}^{\,'}}$) $>$ 2.9 TeV.

³²

AABOUD 2017B exclude m(${{\mathit W}^{\,'}}$, ${{\mathit Z}^{\,'}}$) $<1.49 - 2.31$ TeV depending on the couplings and ${{\mathit W}^{\,'}}/{{\mathit Z}^{\,'}}$ degeneracy assumptions via ${{\mathit W}}{{\mathit H}}$, ${{\mathit Z}}{{\mathit H}}$ search in ${{\mathit p}}{{\mathit p}}$ collisions at 13 TeV with 3.2$~$fb${}^{-1}$ of data.

³³	AAIJ 2017BR search for long-lived hidden valley pions from Higgs decay. Limits are set on the signal strength as a function of the mass and lifetime of the long-lived particle in their Fig. 4 and Tab. 4.

³⁴	AAD 2016O search for high $\mathit E_{T}{{\mathit \ell}}$ + (${{\mathit \ell}}$s or jets) with 3.2 fb${}^{-1}$ at 13 TeV; exclude micro black holes mass $<$ 8 TeV (Fig. 3) for models with two extra dimensions.

³⁵	AAD 2016R search for ${{\mathit W}}{{\mathit W}}$, ${{\mathit W}}{{\mathit Z}}$, resonance in 20.3 fb${}^{-1}$ at 8 TeV data; limits placed on massive RS graviton (Fig. 4).

³⁶

KRASZNAHORKAY 2016 report ${{\mathit p}}$ ${}^{7}{}^{}\mathrm {Li}$ $\rightarrow$ ${}^{8}{}^{}\mathrm {Be}$ $\rightarrow$ ${{\mathit e}}$ ${{\overline{\mathit e}}}$ ${{\mathit N}}$ 5${{\mathit \sigma}}$ resonance at 16.7 MeV-- possible evidence for nuclear interference or new light boson. However, such nuclear interference was ruled out already by ZANG 2017.

³⁷

LEES 2015E search for long-lived neutral particles produced in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ collisions in the Upsilon region, which decays into ${{\mathit e}^{+}}{{\mathit e}^{-}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$, ${{\mathit e}^{\pm}}{{\mathit \mu}^{\mp}}$, ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$, ${{\mathit K}^{+}}{{\mathit K}^{-}}$, or ${{\mathit \pi}^{\pm}}{{\mathit K}^{\mp}}$. See their Fig. 2 for cross section limits.

³⁸

ADAMS 1997B search for a hadron-like neutral particle produced in ${{\mathit p}}{{\mathit N}}$ interactions, which decays into a ${{\mathit \rho}^{0}}$ and a weakly interacting massive particle. Upper limits are given for the ratio to ${{\mathit K}_{{{L}}}}~$production for the mass range $1.2 - 5$ GeV and lifetime $10^{-9} - 10^{-4}~$s. See also our Light Gluino Section.

³⁹

GALLAS 1995 limit is for a weakly interacting neutral particle produced in 800 GeV/$\mathit c$ ${{\mathit p}}{{\mathit N}}$ interactions decaying with a lifetime of $10^{-4} - 10^{-8}~$s. See their Figs.$~$8 and 9. Similar limits are obtained for a stable particle with interaction cross section $10^{-29} - 10^{-33}$ cm${}^{2}$. See Fig.$~$10.

⁴⁰

AKESSON 1991 limit is from weakly interacting neutral long-lived particles produced in ${{\mathit p}}{{\mathit N}}$ reaction at 450 GeV/$\mathit c$ performed at CERN$~$SPS. Bourquin-Gaillard formula is used as the production model. The above limit is for $\tau ~>~10^{-7}~$s. For $\tau ~>~10^{-9}~$s, $\sigma ~<~10^{-30}~$cm${}^{−2}$/nucleon is obtained.

⁴¹

BADIER 1986 looked for long-lived particles at 300 GeV ${{\mathit \pi}^{-}}$ beam dump. The limit applies for nonstrongly interacting neutral or charged particles with mass $>$2 GeV. The limit applies for particle modes, ${{\mathit \mu}^{+}}{{\mathit \pi}^{-}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$, ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$ X, ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{\pm}}$ etc. See their figure 5 for the contours of limits in the mass-$\tau $ plane for each mode.

⁴²

GUSTAFSON 1976 is a 300 GeV FNAL experiment looking for heavy ($\mathit m$ $>$2 GeV) long-lived neutral hadrons in the M4 neutral beam. The above typical value is for $\mathit m$ = 3 GeV and assumes an interaction cross section of 1 mb. Values as a function of mass and interaction cross section are given in figure 2.

References

Except where otherwise noted, content of the 2025 Review of Particle Physics is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) license. The publication of the Review of Particle Physics is supported by US DOE, MEXT and KEK (Japan), INFN (Italy) and CERN. Individual collaborators receive support for their PDG activities from their respective institutes or funding agencies. © 2025. See LBNL disclaimers.

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