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Indirect Limits for Leptoquarks

INSPIRE JSON (beta) PDGID:

VALUE (TeV)

CL%

DOCUMENT ID

TECN

COMMENT

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

ATLS

${{\mathit \mu}}{{\mathit \tau}}{{\mathit q}}{{\mathit t}}$ (${{\mathit q}}$ = ${{\mathit u}}$, ${{\mathit c}}$)

RVUE

${{\mathit \nu}}$-nucleus scattering

CMS

${{\mathit q}}$ ${{\overline{\mathit q}}^{\,'}}$ $\rightarrow$ ${{\mathit \tau}}{{\mathit \nu}}$

CMS

${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \tau}}{{\mathit \tau}}$

RVUE

First generation

RVUE

${{\mathit B}}$ decays

RVUE

${{\mathit K}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit \nu}}{{\mathit \nu}}$

$> 3.1$

95

ZEUS

First generation

RVUE

${{\mathit \tau}}$, ${{\mathit \mu}}$, ${{\mathit e}}$, ${{\mathit K}}$

RVUE

${{\mathit D}}$ decays

RVUE

${{\mathit D}}$ decays

RVUE

neutral ${{\mathit K}}$ mixing, rare ${{\mathit K}}$ decays

RVUE

${{\mathit q}}$ ${{\overline{\mathit q}}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$

$\text{> 14}$

95

RVUE

${{\mathit B}}$ $_{s,d}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$

RVUE

${{\mathit B}}$ $\rightarrow$ ${{\mathit D}^{(*)}}{{\mathit \tau}}{{\overline{\mathit \nu}}}$, ${{\mathit B}}$ $\rightarrow$ ${{\mathit X}_{{{s}}}}{{\mathit \nu}}{{\overline{\mathit \nu}}}$

RVUE

${{\mathit b}}$ $\rightarrow$ ${{\mathit s}}{{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$

$> 2.5$

95

H1

First generation

RVUE

scalar, weak singlet, charge 4/3

H1

Lepton-flavor violation

$> 0.49$

95

ALEP

${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}$

RVUE

${{\mathit K}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \mu}}$, ${{\mathit B}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \tau}}$

ZEUS

Lepton-flavor violation

$>1.7$

96

H1

First generation

$> 46$

90

BELL

Pati-Salam type

ZEUS

Repl. by CHEKANOV 2005A

$>1.7$

95

RVUE

First generation

$>0.39$

95

L3

${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\mathit q}}$

$>1.5$

95

H1

First generation

$>0.2$

95

ALEP

Repl. by SCHAEL 2007A

RVUE

${}^{}\mathrm {Cs}$

RVUE

Lepton flavor violation

$>0.74$

95

RVUE

$\mathit S_{1}$ leptoquark

OPAL

$>19.3$

95

CDF

${{\mathit B}_{{{s}}}}$ $\rightarrow$ ${{\mathit e}^{\pm}}{{\mathit \mu}^{\mp}}$, Pati-Salam type

L3

${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}$

OPAL

${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}$, ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit b}}{{\overline{\mathit b}}}$

$>0.76$

95

RVUE

${{\widetilde{\mathit R}}_{{{2}}}}$ leptoquark

ZEUS

Lepton-flavor violation

RVUE

${{\mathit B}}$ $\rightarrow$ ${{\mathit \tau}^{+}}{{\mathit \tau}^{-}}$ (X)

RVUE

${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}$

$>1200$

RVUE

Pati-Salam type

RVUE

Third generation scalar leptoquark

$>0.3$

95

RVUE

Spin-0 leptoquark coupled to ${{\overline{\mathit e}}_{{{R}}}}{{\mathit t}_{{{L}}}}$

RVUE

$>18$

RVUE

Pati-Salam type

$>0.43$

95

RVUE

First generation spin-1 leptoquark

$>0.44$

95

RVUE

First generation spin-0 leptoquark

RVUE

$\mathit P$ and $\mathit T$ violation

$>1$

RVUE

Nonchiral spin-0 leptoquark

$>125$

RVUE

Nonchiral spin-1 leptoquark

¹	AAD 2024W search for leptoquark induced ${{\mathit \mu}}{{\mathit \tau}}{{\mathit q}}{{\mathit t}}$ (${{\mathit q}}$ = ${{\mathit u}}$, ${{\mathit c}}$) contact interaction in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 13 TeV. See their Fig. 7b for limits in mass-coupling plane.

²	CALABRESE 2023 obtain limits on leptoquark coupling from coherent ${{\mathit \nu}}$-nucleus scattering data collected by COHERENT experiment. See their Fig. 3 for limits in mass-coupling plane.

³	TUMASYAN 2023AW search for ${{\mathit \tau}}{{\mathit \nu}}$ events mediated by ${{\mathit t}}$-channel leptoquark exchange in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 13 TeV. See their Fig. 10 for limits in mass-coupling plane.

⁴

TUMASYAN 2023S search for leptoquark induced ${{\mathit b}}$ ${{\overline{\mathit b}}}$ $\rightarrow$ ${{\mathit \tau}^{+}}{{\mathit \tau}^{-}}$ process in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 13 TeV. See their Fig. 12 for limits on a vector ${{\mathit b}}{{\mathit \tau}}$ leptoquark in mass-coupling plane.

⁵

CRIVELLIN 2021A set limits on coupling strengths of scalar and vector leptoquarks using ${{\mathit K}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit \nu}}{{\mathit \nu}}$, ${{\mathit K}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit e}^{+}}{{\mathit e}^{-}}$, ${{\mathit K}^{0}}−{{\overline{\mathit K}}^{0}}$ and ${{\mathit D}^{0}}−{{\overline{\mathit D}}^{0}}$ mixings, and weak neutral current measurements. See their Fig. 2 and Fig. 3 for the limits in mass-coupling plane.

⁶

AEBISCHER 2020 explain the ${{\mathit B}}$ decay anomalies using four-fermion operator Wilson coefficents. See their Table 1. These Wilson coefficients may be generated by a ${{\mathit U}_{{{1}}}}$ vector leptoquark with ${{\mathit U}_{{{1}}}}$ transforming as (3,1)$_{2/3}$ under the SM gauge group. See their Figures 6, 7, 8 for the regions of the LQ parameter space which explains the ${{\mathit B}}$ anomalies and avoids the indirect low energy constraints.

⁷

DEPPISCH 2020 limits on the lepton-number-violating higher-dimensional-operators are derived from ${{\mathit K}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit \nu}}{{\mathit \nu}}$ in the standard model effective field theory. These higher-dimensional-operators may be induced from leptoquark-exchange diagrams.

⁸

ABRAMOWICZ 2019 obtain a limit on $\lambda /{{\mathit M}_{{{LQ}}}}$ $>$ 1.16 TeV${}^{-1}$ for weak isotriplet spin-0 leptoquark ${{\mathit S}_{{{1}}}^{L}}$. We obtain the limit quoted above by converting the limit on $\lambda /{{\mathit M}_{{{LQ}}}}$ for ${{\mathit S}_{{{1}}}^{L}}$ assuming $\lambda $ = $\sqrt {4 \pi }$. See their Table 5 for the limits of leptoquarks with different quantum numbers. These limits are derived from bounds of ${{\mathit e}}{{\mathit q}}$ contact interactions.

⁹	MANDAL 2019 give bounds on leptoquarks from ${{\mathit \tau}}$-decays, leptonic dipole moments, lepton-flavor-violating processes, and ${{\mathit K}}$ decays.

¹⁰

ZHANG 2018A give bounds on leptoquark induced four-fermion interactions from ${{\mathit D}}$ $\rightarrow$ ${{\mathit K}}{{\mathit \ell}}{{\mathit \nu}}$. The authors inform us that the shape parameter of the vector form factor in both the abstract and the conclusions of ZHANG 2018A should be $\mathit r_{+1}$ = $2.16$ $\pm0.07$ rather than $\pm0.007$. The numbers listed in their Table 7 are correct.

¹¹	BARRANCO 2016 give bounds on leptoquark induced four-fermion interactions from ${{\mathit D}}$ $\rightarrow$ ${{\mathit K}}{{\mathit \ell}}{{\mathit \nu}}$ and ${{\mathit D}_{{{s}}}}$ $\rightarrow$ ${{\mathit \ell}}{{\mathit \nu}}$.

¹²

KUMAR 2016 gives bound on SU(2) singlet scalar leptoquark with chrge $−$1/3 from ${{\mathit K}^{0}}−{{\overline{\mathit K}}^{0}}$ mixing, ${{\mathit K}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit \nu}}{{\overline{\mathit \nu}}}$, ${{\mathit K}_L^0}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$, and ${{\mathit K}_L^0}$ $\rightarrow$ ${{\mathit \mu}^{\pm}}{{\mathit e}^{\mp}}$ decays.

¹³	BESSAA 2015 obtain limit on leptoquark induced four-fermion interactions from the ATLAS and CMS limit on the ${{\overline{\mathit q}}}{{\mathit q}}{{\overline{\mathit e}}}{{\mathit e}}$ contact interactions.

¹⁴	SAHOO 2015A obtain limit on leptoquark induced four-fermion interactions from ${{\mathit B}}$ $_{s,d}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$ for $\lambda $ $\simeq{}$ $\mathit O$(1).

¹⁵	SAKAKI 2013 explain the ${{\mathit B}}$ $\rightarrow$ ${{\mathit D}^{(*)}}{{\mathit \tau}}{{\overline{\mathit \nu}}}$ anomaly using Wilson coefficients of leptoquark-induced four-fermion operators.

¹⁶	KOSNIK 2012 obtains limits on leptoquark induced four-fermion interactions from ${{\mathit b}}$ $\rightarrow$ ${{\mathit s}}{{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$ decays.

¹⁷	AARON 2011C limit is for weak isotriplet spin-0 leptoquark at strong coupling ${{\mathit \lambda}}$ = $\sqrt {4\pi }$. For the limits of leptoquarks with different quantum numbers, see their Table 3. Limits are derived from bounds of ${{\mathit e}}{{\mathit q}}$ contact intereractions.

¹⁸	DORSNER 2011 give bounds on scalar, weak singlet, charge 4/3 leptoquark from ${{\mathit K}}$, ${{\mathit B}}$, ${{\mathit \tau}}$ decays, meson mixings, $\mathit LFV$, $\mathit g−$2 and ${{\mathit Z}}$ $\rightarrow$ ${{\mathit b}}{{\overline{\mathit b}}}$.

¹⁹	AKTAS 2007A search for lepton-flavor violation in ${{\mathit e}}{{\mathit p}}$ collision. See their Tables $4 - 7$ for limits on lepton-flavor violating four-fermion interactions induced by various leptoquarks.

²⁰	SCHAEL 2007A limit is for the weak-isoscalar spin-0 left-handed leptoquark with the coupling of electromagnetic strength. For the limits of leptoquarks with different quantum numbers, see their Table 35.

²¹	SMIRNOV 2007 obtains mass limits for the vector and scalar chiral leptoquark states from ${{\mathit K}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \mu}}$, ${{\mathit B}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \tau}}$ decays.

²²	CHEKANOV 2005 search for various leptoquarks with lepton-flavor violating couplings. See their Figs.6--10 and Tables 1--8 for detailed limits.

²³	ADLOFF 2003 limit is for the weak isotriplet spin-0 leptoquark at strong coupling $\lambda =\sqrt {4{{\mathit \pi}} }$. For the limits of leptoquarks with different quantum numbers, see their Table$~$3. Limits are derived from bounds on ${{\mathit e}^{\pm}}{{\mathit q}}$ contact interactions.

²⁴	The bound is derived from B(${{\mathit B}^{0}}$ $\rightarrow$ ${{\mathit e}^{\pm}}{{\mathit \mu}^{\mp}}$) $<$ $1.7 \times 10^{-7}$.

²⁵	CHEKANOV 2002 search for lepton-flavor violation in ${{\mathit e}}{{\mathit p}}$ collisions. See their Tables$~1 - 4$ for limits on lepton-flavor violating and four-fermion interactions induced by various leptoquarks.

²⁶	CHEUNG 2001B quoted limit is for a scalar, weak isoscalar, charge $−$1/3 leptoquark with a coupling of electromagnetic strength. The limit is derived from bounds on contact interactions in a global electroweak analysis. For the limits of leptoquarks with different quantum numbers, see Table$~$5.

²⁷	ACCIARRI 2000P limit is for the weak isoscalar spin-0 leptoquark with the coupling of electromagnetic strength. For the limits of leptoquarks with different quantum numbers, see their Table$~$4.

²⁸

ADLOFF 2000 limit is for the weak isotriplet spin-0 leptoquark at strong coupling, $\lambda =\sqrt {4\pi }$. For the limits of leptoquarks with different quantum numbers, see their Table$~$2. ADLOFF 2000 limits are from the $\mathit Q{}^{2}$ spectrum measurement of ${{\mathit e}^{+}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit e}^{+}}$ X.

²⁹

BARATE 2000I search for deviations in cross section and jet-charge asymmetry in ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\overline{\mathit q}}}{{\mathit q}}$ due to $\mathit t$-channel exchange of a leptoquark at $\sqrt {\mathit s }$=130 to 183 GeV. Limits for other scalar and vector leptoquarks are also given in their Table$~$22.

³⁰	BARGER 2000 explain the deviation of atomic parity violation in cesium atoms from prediction is explained by scalar leptoquark exchange.

³¹	GABRIELLI 2000 calculate various process with lepton flavor violation in leptoquark models.

³²	ZARNECKI 2000 limit is derived from data of HERA, LEP, and Tevatron and from various low-energy data including atomic parity violation. Leptoquark coupling with electromagnetic strength is assumed.

³³	ABBIENDI 1999 limits are from ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}$ cross section at $130 - 136$, $161 - 172$, 183 GeV. See their Fig.$~$8 and Fig.$~$9 for limits in mass-coupling plane.

³⁴

ABE 1998V quoted limit is from B(${{\mathit B}_{{{s}}}}$ $\rightarrow$ ${{\mathit e}^{\pm}}{{\mathit \mu}^{\mp}})<8.2 \times 10^{-6}$. ABE 1998V also obtain a similar limit on $\mathit M_{LQ}>20.4$ TeV from B(${{\mathit B}_{{{d}}}}$ $\rightarrow$ ${{\mathit e}^{\pm}}{{\mathit \mu}^{\mp}})<4.5 \times 10^{-6}$. Both bounds assume the non-canonical association of the ${{\mathit b}}~$quark with electrons or muons under SU(4).

³⁵

ACCIARRI 1998J limit is from ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}$ cross section at $\sqrt {\mathit s }$= $130 - 172$ GeV which can be affected by the ${{\mathit t}}-~$and ${{\mathit u}}$-channel exchanges of leptoquarks. See their Fig.$~$4 and Fig.$~$5 for limits in the mass-coupling plane.

³⁶

ACKERSTAFF 1998V limits are from ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}$ and ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit b}}{{\overline{\mathit b}}}$ cross sections at $\sqrt {\mathit s }$ = $130 - 172$ GeV, which can be affected by the $\mathit t$- and $\mathit u$-channel exchanges of leptoquarks. See their Fig.$~$21 and Fig.$~$22 for limits of leptoquarks in mass-coupling plane.

³⁷

DEANDREA 1997 limit is for ${{\widetilde{\mathit R}}_{{{2}}}}$ leptoquark obtained from atomic parity violation (APV). The coupling of leptoquark is assumed to be electromagnetic strength. See Table$~$2 for limits of the four-fermion interactions induced by various scalar leptoquark exchange. DEANDREA 1997 combines APV limit and limits from Tevatron and HERA. See Fig.$~1 - 4$ for combined limits of leptoquark in mass-coupling plane.

³⁸	DERRICK 1997 search for lepton-flavor violation in ${{\mathit e}}{{\mathit p}}$ collision. See their Tables$~$2--5 for limits on lepton-flavor violating four-fermion interactions induced by various leptoquarks.

³⁹	GROSSMAN 1997 estimate the upper bounds on the branching fraction ${{\mathit B}}$ $\rightarrow$ ${{\mathit \tau}^{+}}{{\mathit \tau}^{-}}$ (X) from the absence of the ${{\mathit B}}$ decay with large missing energy. These bounds can be used to constrain leptoquark induced four-fermion interactions.

⁴⁰

JADACH 1997 limit is from ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit q}}{{\overline{\mathit q}}}$ cross section at $\sqrt {\mathit s }=172.3$ GeV which can be affected by the ${{\mathit t}}$- and ${{\mathit u}}$-channel exchanges of leptoquarks. See their Fig.$~$1 for limits on vector leptoquarks in mass-coupling plane.

⁴¹

KUZNETSOV 1995B use ${{\mathit \pi}}$, ${{\mathit K}}$, ${{\mathit B}}$, ${{\mathit \tau}}$ decays and ${{\mathit \mu}}{{\mathit e}}$ conversion and give a list of bounds on the leptoquark mass and the fermion mixing matrix in the Pati-Salam model. The quoted limit is from ${{\mathit K}_{{{L}}}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit e}}$ decay assuming zero mixing.

⁴²	MIZUKOSHI 1995 calculate the one-loop radiative correction to the ${{\mathit Z}}$-physics parameters in various scalar leptoquark models. See their Fig.$~$4 for the exclusion plot of third generation leptoquark models in mass-coupling plane.

⁴³

BHATTACHARYYA 1994 limit is from one-loop radiative correction to the leptonic decay width of the ${{\mathit Z}}$. ${\mathit m}_{{{\mathit H}}}$=250 GeV, ${{\mathit \alpha}_{{{s}}}}({\mathit m}_{{{\mathit Z}}})=0.12$, ${\mathit m}_{{{\mathit t}}}$=180 GeV, and the electroweak strength of leptoquark coupling are assumed. For leptoquark coupled to ${{\overline{\mathit e}}_{{{L}}}}{{\mathit t}_{{{R}}}}$, ${{\overline{\mathit \mu}}}{{\mathit t}}$, and ${{\overline{\mathit \tau}}}{{\mathit t}}$, see Fig.$~$2 in BHATTACHARYYA 1994B erratum and Fig.$~$3.

⁴⁴	DAVIDSON 1994 gives an extensive list of the bounds on leptoquark-induced four-fermion interactions from ${{\mathit \pi}}$, ${{\mathit K}}$, ${{\mathit D}}$, ${{\mathit B}}$, ${{\mathit \mu}}$, ${{\mathit \tau}}$ decays and meson mixings, $\mathit etc$. See Table$~$15 of DAVIDSON 1994 for detail.

⁴⁵	KUZNETSOV 1994 gives mixing independent bound of the Pati-Salam leptoquark from the cosmological limit on ${{\mathit \pi}^{0}}$ $\rightarrow$ ${{\overline{\mathit \nu}}}{{\mathit \nu}}$.

⁴⁶

LEURER 1994, LEURER 1994B limits are obtained from atomic parity violation and apply to any chiral leptoquark which couples to the first generation with electromagnetic strength. For a nonchiral leptoquark, universality in ${{\mathit \pi}}_{{{\mathit \ell}}2}$ decay provides a much more stringent bound.

⁴⁷	MAHANTA 1994 gives bounds of $\mathit P$- and $\mathit T$-violating scalar-leptoquark couplings from atomic and molecular experiments.

⁴⁸

From (${{\mathit \pi}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \nu}})/({{\mathit \pi}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \nu}}$) ratio. SHANKER 1982 assumes the leptoquark induced four-fermion coupling 4$\mathit g{}^{2}/\mathit M{}^{2}$ (${{\overline{\mathit \nu}}}_{\mathit eL}$ $\mathit u_{\mathit R}$) (${{\overline{\mathit d}}_{{{L}}}}{{\mathit e}_{{{R}}}}$)with $\mathit g=0.004$ for spin-0 leptoquark and $\mathit g{}^{2}/\mathit M{}^{2}$ (${{\overline{\mathit \nu}}}_{\mathit eL}{{\mathit \gamma}_{{{\mu}}}}{{\mathit u}_{{{L}}}}$) (${{\overline{\mathit d}}_{{{R}}}}{{\mathit \gamma}}{}^{{{\mathit \mu}}}$ ${{\mathit e}_{{{R}}}}$) with $\mathit g≅0.6$ for spin-1 leptoquark.

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