Abstract
We implement scalar and vector leptoquark (LQ) models in the universal FeynRules output (UFO) format assuming the Standard Model fermion content and conservation of baryon and lepton numbers. Scalar LQ implementations include next-to-leading order (NLO) QCD corrections. We report the NLO QCD inclusive cross sections in proton-proton collisions at 13 TeV, 14 TeV, and 27 TeV for all on-shell LQ production processes. These comprise (i) LQ pair production (pp → ΦΦ) and (ii) single LQ + lepton production (pp → Φℓ) for all initial quark flavours (u, d, s, c, and b). Vector LQ implementation includes adjustable non-minimal QCD coupling. We discuss several aspects of LQ searches at a hadron collider, emphasising the implications of SU(2) gauge invariance, electroweak and flavour constraints, on the possible signatures. Finally, we outline the high-pT search strategy for LQs recently proposed in the literature to resolve experimental anomalies in B-meson decays. In this context, we stress the importance of complementarity of the three LQ related processes, namely, pp → ΦΦ, pp → Φℓ, and pp → ℓℓ.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
References
J.C. Pati and A. Salam, Unified lepton-hadron symmetry and a gauge theory of the basic interactions, Phys. Rev. D 8 (1973) 1240 [INSPIRE].
S. Davidson, D.C. Bailey and B.A. Campbell, Model independent constraints on leptoquarks from rare processes, Z. Phys. C 61 (1994) 613 [hep-ph/9309310] [INSPIRE].
J.L. Hewett and T.G. Rizzo, Much ado about leptoquarks: a comprehensive analysis, Phys. Rev. D 56 (1997) 5709 [hep-ph/9703337] [INSPIRE].
P. Nath and P. Fileviez Perez, Proton stability in grand unified theories, in strings and in branes, Phys. Rept. 441 (2007) 191 [hep-ph/0601023] [INSPIRE].
I. Doršner et al., Physics of leptoquarks in precision experiments and at particle colliders, Phys. Rept. 641 (2016) 1 [arXiv:1603.04993] [INSPIRE].
I. Dorsner, S. Fajfer and A. Greljo, Cornering scalar leptoquarks at LHC, JHEP 10 (2014) 154 [arXiv:1406.4831] [INSPIRE].
T. Mandal, S. Mitra and S. Seth, Single productions of colored particles at the LHC: an example with scalar leptoquarks, JHEP 07 (2015) 028 [arXiv:1503.04689] [INSPIRE].
B. Diaz, M. Schmaltz and Y.-M. Zhong, The leptoquark Hunter’s guide: pair production, JHEP 10 (2017) 097 [arXiv:1706.05033] [INSPIRE].
P. Bandyopadhyay and R. Mandal, Revisiting scalar leptoquark at the LHC, arXiv:1801.04253 [INSPIRE].
M. Krämer, T. Plehn, M. Spira and P.M. Zerwas, Pair production of scalar leptoquarks at the CERN LHC, Phys. Rev. D 71 (2005) 057503 [hep-ph/0411038] [INSPIRE].
T. Mandal, S. Mitra and S. Seth, Pair production of scalar leptoquarks at the LHC to NLO parton shower accuracy, Phys. Rev. D 93 (2016) 035018 [arXiv:1506.07369] [INSPIRE].
A. Alves, O. Eboli and T. Plehn, Stop lepton associated production at hadron colliders, Phys. Lett. B 558 (2003) 165 [hep-ph/0211441] [INSPIRE].
J.B. Hammett and D.A. Ross, NLO leptoquark production and decay: the narrow-width approximation and beyond, JHEP 07 (2015) 148 [arXiv:1501.06719] [INSPIRE].
D. Buttazzo, A. Greljo, G. Isidori and D. Marzocca, B-physics anomalies: a guide to combined explanations, JHEP 11 (2017) 044 [arXiv:1706.07808] [INSPIRE].
W. Buchmüller, R. Ruckl and D. Wyler, Leptoquarks in lepton-quark collisions, Phys. Lett. B 191 (1987) 442 [Erratum ibid. B 448 (1999) 320] [INSPIRE].
A. Alloul et al., FeynRules 2.0 — A complete toolbox for tree-level phenomenology, Comput. Phys. Commun. 185 (2014) 2250 [arXiv:1310.1921] [INSPIRE].
J. Alwall et al., The automated computation of tree-level and next-to-leading order differential cross sections and their matching to parton shower simulations, JHEP 07 (2014) 079 [arXiv:1405.0301] [INSPIRE].
C. Degrande, Automatic evaluation of UV and R2 terms for beyond the standard model lagrangians: a proof-of-principle, Comput. Phys. Commun. 197 (2015) 239 [arXiv:1406.3030] [INSPIRE].
T. Hahn, Generating Feynman diagrams and amplitudes with FeynArts 3, Comput. Phys. Commun. 140 (2001) 418 [hep-ph/0012260] [INSPIRE].
V. Hirschi et al., Automation of one-loop QCD corrections, JHEP 05 (2011) 044 [arXiv:1103.0621] [INSPIRE].
T. Peraro, Ninja: automated integrand reduction via Laurent expansion for one-loop amplitudes, Comput. Phys. Commun. 185 (2014) 2771 [arXiv:1403.1229] [INSPIRE].
V. Hirschi and T. Peraro, Tensor integrand reduction via Laurent expansion, JHEP 06 (2016) 060 [arXiv:1604.01363] [INSPIRE].
S. Frixione, Z. Kunszt and A. Signer, Three jet cross-sections to next-to-leading order, Nucl. Phys. B 467 (1996) 399 [hep-ph/9512328] [INSPIRE].
R. Frederix, S. Frixione, F. Maltoni and T. Stelzer, Automation of next-to-leading order computations in QCD: The FKS subtraction, JHEP 10 (2009) 003 [arXiv:0908.4272] [INSPIRE].
T. Plehn, H. Spiesberger, M. Spira and P.M. Zerwas, Formation and decay of scalar leptoquarks/squarks in ep collisions, Z. Phys. C 74 (1997) 611 [hep-ph/9703433] [INSPIRE].
L. Di Luzio, A. Greljo and M. Nardecchia, Gauge leptoquark as the origin of B-physics anomalies, Phys. Rev. D 96 (2017) 115011 [arXiv:1708.08450] [INSPIRE].
M. Bordone, C. Cornella, J. Fuentes-Martin and G. Isidori, A three-site gauge model for flavor hierarchies and flavor anomalies, Phys. Lett. B 779 (2018) 317 [arXiv:1712.01368] [INSPIRE].
R. Barbieri and A. Tesi, B-decay anomalies in Pati-Salam SU(4), Eur. Phys. J. C 78 (2018) 193 [arXiv:1712.06844] [INSPIRE].
J. Butterworth et al., PDF4LHC recommendations for LHC Run II, J. Phys. G 43 (2016) 023001 [arXiv:1510.03865] [INSPIRE].
J. Guena, M. Lintz and M.A. Bouchiat, Measurement of the parity violating 6S-7S transition amplitude in cesium achieved within 2 × 10−13 atomic-unit accuracy by stimulated-emission detection, Phys. Rev. A 71 (2005) 042108 [physics/0412017] [INSPIRE].
C.S. Wood et al., Measurement of parity nonconservation and an anapole moment in cesium, Science 275 (1997) 1759.
J. Blumlein, E. Boos and A. Kryukov, Leptoquark pair production in hadronic interactions, Z. Phys. C 76 (1997) 137 [hep-ph/9610408] [INSPIRE].
NNPDF collaboration, R.D. Ball et al., Parton distributions for the LHC Run II, JHEP 04 (2015)040 [arXiv:1410.8849] [INSPIRE].
J. Pumplin, D.R. Stump, J. Huston, H.L. Lai, P.M. Nadolsky and W.K. Tung, New generation of parton distributions with uncertainties from global QCD analysis, JHEP 07 (2002)012 [hep-ph/0201195] [INSPIRE].
BaBar collaboration, J.P. Lees et al., Measurement of an excess of \( \overline{B}\to {D^{\Big(}}^{\ast \Big)}\tau -{\overline{\nu}}_{\tau } \) decays and implications for charged Higgs bosons, Phys. Rev. D 88 (2013) 072012 [arXiv:1303.0571] [INSPIRE].
Belle collaboration, S. Hirose et al., Measurement of the τ lepton polarization and R(D ∗) in the decay \( \overline{B}\to {D}^{\ast}\tau -{\overline{\nu}}_{\tau } \), Phys. Rev. Lett. 118 (2017) 211801 [arXiv:1612.00529] [INSPIRE].
LHCb collaboration, Measurement of the ratio of branching fractions \( \mathrm{\mathcal{B}}\left({\overline{B}}^0\to {D}^{\ast +}{\tau}^{-}{\overline{\nu}}_{\tau}\right)/\mathrm{\mathcal{B}}\left({\overline{B}}^0\to {D}^{\ast +}{\mu}^{-}{\overline{\nu}}_{\mu}\right) \), Phys. Rev. Lett. 115 (2015) 111803 [arXiv:1506.08614] [INSPIRE].
LHCb collaboration, Test of lepton universality using B + → K + ℓ + ℓ − decays, Phys. Rev. Lett. 113 (2014) 151601 [arXiv:1406.6482] [INSPIRE].
LHCb collaboration, Test of lepton universality with B 0 → K ∗0 ℓ + ℓ − decays, JHEP 08 (2017) 055 [arXiv:1705.05802] [INSPIRE].
LHCb collaboration, Measurement of form-factor-independent observables in the decay B 0 → K ∗0 μ + μ −, Phys. Rev. Lett. 111 (2013) 191801 [arXiv:1308.1707] [INSPIRE].
LHCb collaboration, Angular analysis of the B 0 → K ∗0 μ + μ − decay using 3 fb −1 of integrated luminosity, JHEP 02 (2016) 104 [arXiv:1512.04442] [INSPIRE].
B. Capdevila et al., Patterns of new physics in b → sℓ + ℓ − transitions in the light of recent data, JHEP 01 (2018) 093 [arXiv:1704.05340] [INSPIRE].
W. Altmannshofer, P. Stangl and D.M. Straub, Interpreting hints for lepton flavor universality violation, Phys. Rev. D 96 (2017) 055008 [arXiv:1704.05435] [INSPIRE].
L.-S. Geng et al., Towards the discovery of new physics with lepton-universality ratios of b→sℓℓ decays, Phys. Rev. D 96 (2017) 093006 [arXiv:1704.05446] [INSPIRE].
G. D’Amico et al., Flavour anomalies after the R K∗ measurement, JHEP 09 (2017) 010 [arXiv:1704.05438] [INSPIRE].
HFLAV collaboration, Y. Amhis et al., Averages of b-hadron, c-hadron and τ -lepton properties as of summer 2016, Eur. Phys. J. C 77 (2017) 895 [arXiv:1612.07233] [INSPIRE].
L. Di Luzio and M. Nardecchia, What is the scale of new physics behind the B-flavour anomalies?, Eur. Phys. J. C 77 (2017) 536 [arXiv:1706.01868] [INSPIRE].
M. Freytsis, Z. Ligeti and J.T. Ruderman, Flavor models for \( \overline{B}\to {D^{\Big(}}^{\ast \Big)}\tau \overline{\nu} \), Phys. Rev. D 92 (2015) 054018 [arXiv:1506.08896] [INSPIRE].
R. Alonso, B. Grinstein and J. Martin Camalich, Lepton universality violation and lepton flavor conservation in B-meson decays, JHEP 10 (2015) 184 [arXiv:1505.05164] [INSPIRE].
A. Greljo, G. Isidori and D. Marzocca, On the breaking of lepton flavor universality in B decays, JHEP 07 (2015) 142 [arXiv:1506.01705] [INSPIRE].
L. Calibbi, A. Crivellin and T. Ota, Effective field theory approach to \( b\to s\ell {\ll}^{\prime },\ B\to {K}^{\ast}\nu \overline{\nu} \) and B → D ∗ τ ν with third generation couplings, Phys. Rev. Lett. 115 (2015) 181801 [arXiv:1506.02661] [INSPIRE].
A. Crivellin, D. Müller and T. Ota, Simultaneous explanation of R(D ∗) and b → sμ + μ − : the last scalar leptoquarks standing, JHEP 09 (2017) 040 [arXiv:1703.09226] [INSPIRE].
R. Alonso, B. Grinstein and J. Martin Camalich, Lifetime of B − c constrains explanations for anomalies in B → D (∗) τ ν, Phys. Rev. Lett. 118 (2017) 081802 [arXiv:1611.06676] [INSPIRE].
F. Feruglio, P. Paradisi and A. Pattori, Revisiting lepton flavor universality in B decays, Phys. Rev. Lett. 118 (2017) 011801 [arXiv:1606.00524] [INSPIRE].
F. Feruglio, P. Paradisi and A. Pattori, On the importance of electroweak corrections for B anomalies, JHEP 09 (2017) 061 [arXiv:1705.00929] [INSPIRE].
D.A. Faroughy, A. Greljo and J.F. Kamenik, Confronting lepton flavor universality violation in B decays with high-p T τ lepton searches at LHC, Phys. Lett. B 764 (2017) 126 [arXiv:1609.07138] [INSPIRE].
ATLAS collaboration, Searches for scalar leptoquarks in pp collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector, Eur. Phys. J. C 76 (2016) 5 [arXiv:1508.04735] [INSPIRE].
CMS collaboration, Search for third-generation scalar leptoquarks and heavy right-handed neutrinos in final states with two tau leptons and two jets in proton-proton collisions at \( \sqrt{s}=13 \) TeV, JHEP 07(2017)121 [arXiv:1703.03995] [INSPIRE].
I. Doršner, S. Fajfer, D.A. Faroughy and N. Košnik, The role of the S 3 GUT leptoquark in flavor universality and collider searches, arXiv:1706.07779 [INSPIRE].
A. Greljo and D. Marzocca, High-p T dilepton tails and flavor physics, Eur. Phys. J. C 77 (2017) 548 [arXiv:1704.09015] [INSPIRE].
B.C. Allanach, B. Gripaios and T. You, The case for future hadron colliders from B→K (∗) μ + μ − decays, JHEP 03(2018)021 [arXiv:1710.06363] [INSPIRE].
Open Access
This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.
Author information
Authors and Affiliations
Corresponding author
Additional information
ArXiv ePrint: 1801.07641
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.
The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.
To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.
About this article
Cite this article
Doršner, I., Greljo, A. Leptoquark toolbox for precision collider studies. J. High Energ. Phys. 2018, 126 (2018). https://doi.org/10.1007/JHEP05(2018)126
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP05(2018)126