Abstract
We comprehensively examine precision predictions for scalar leptoquark pair production at the LHC. In particular, we investigate the impact of lepton t-channel exchange diagrams that are potentially relevant in the context of leptoquark scenarios providing an explanation for the flavour anomalies. We also evaluate the corresponding total rates at the next-to-leading order in QCD. Moreover, we complement this calculation with the resummation of soft-gluon radiation at the next-to-next-to-leading logarithmic accuracy, hence providing the most precise predictions for leptoquark pair production at the LHC to date. Relying on a variety of benchmark scenarios favoured by the anomalies, our results exhibit an interesting interplay between the t-channel diagram contributions, the flavour texture satisfied by the leptoquark Yukawa couplings, the leptoquark masses and their representations under the Standard Model gauge group, as well as the chosen set of parton densities used for the numerical evaluations. The net effect on a cross section turns out to be very non-generic and ranges up to about 60% with respect to the usual next-to-leading-order predictions in QCD (i.e. without any t-channel contribution) for some scenarios considered. Dedicated calculations are thus required for any individual leptoquark model that could be considered in a collider analysis in order to assess the size of the studied corrections. In order to facilitate such calculations we provide dedicated public numerical packages.
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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].
J.C. Pati and A. Salam, Lepton Number as the Fourth Color, Phys. Rev. D 10 (1974) 275 [Erratum ibid. 11 (1975) 703] [INSPIRE].
H. Georgi and S.L. Glashow, Unity of All Elementary Particle Forces, Phys. Rev. Lett. 32 (1974) 438 [INSPIRE].
H. Fritzsch and P. Minkowski, Unified Interactions of Leptons and Hadrons, Annals Phys. 93 (1975) 193 [INSPIRE].
G. Senjanović and A. Sokorac, Light Leptoquarks in SO(10), Z. Phys. C 20 (1983) 255 [INSPIRE].
P.H. Frampton and B.-H. Lee, SU(15) grand unification, Phys. Rev. Lett. 64 (1990) 619 [INSPIRE].
H. Murayama and T. Yanagida, A viable SU(5) GUT with light leptoquark bosons, Mod. Phys. Lett. A 7 (1992) 147 [INSPIRE].
S. Dimopoulos and L. Susskind, Mass Without Scalars, Nucl. Phys. B 155 (1979) 237 [INSPIRE].
E. Eichten and K.D. Lane, Dynamical Breaking of Weak Interaction Symmetries, Phys. Lett. B 90 (1980) 125 [INSPIRE].
E. Farhi and L. Susskind, Technicolor, Phys. Rept. 74 (1981) 277 [INSPIRE].
B. Schrempp and F. Schrempp, Light leptoquarks, Phys. Lett. B 153 (1985) 101 [INSPIRE].
K.D. Lane and M.V. Ramana, Walking technicolor signatures at hadron colliders, Phys. Rev. D 44 (1991) 2678 [INSPIRE].
J.L. Hewett and T.G. Rizzo, Low-Energy Phenomenology of Superstring Inspired E6 Models, Phys. Rept. 183 (1989) 193 [INSPIRE].
G.R. Farrar and P. Fayet, Phenomenology of the Production, Decay, and Detection of New Hadronic States Associated with Supersymmetry, Phys. Lett. B 76 (1978) 575 [INSPIRE].
R. Barbier et al., R-parity violating supersymmetry, Phys. Rept. 420 (2005) 1 [hep-ph/0406039] [INSPIRE].
BaBar collaboration, Evidence for an excess of \( \overline{B} \) → D(*)τ−\( \overline{\nu} \)τ decays, Phys. Rev. Lett. 109 (2012) 101802 [arXiv:1205.5442] [INSPIRE].
Belle collaboration, Test of Lepton-Flavor Universality in B → K*ℓ+ℓ− Decays at Belle, Phys. Rev. Lett. 126 (2021) 161801 [arXiv:1904.02440] [INSPIRE].
BELLE collaboration, Test of lepton flavor universality and search for lepton flavor violation in B → Kℓℓ decays, JHEP 03 (2021) 105 [arXiv:1908.01848] [INSPIRE].
Belle collaboration, Measurement of \( \mathcal{R} \)(D) and \( \mathcal{R} \)(D*) with a semileptonic tagging method, Phys. Rev. Lett. 124 (2020) 161803 [arXiv:1910.05864] [INSPIRE].
LHCb collaboration, Test of lepton universality with B0 → K*0ℓ+ℓ− decays, JHEP 08 (2017) 055 [arXiv:1705.05802] [INSPIRE].
LHCb collaboration, Measurement of the ratio of the B0 → D*−τ+ντ and B0 → D*−μ+νμ branching fractions using three-prong τ-lepton decays, Phys. Rev. Lett. 120 (2018) 171802 [arXiv:1708.08856] [INSPIRE].
LHCb collaboration, Search for lepton-universality violation in B+ → K+ℓ+ℓ− decays, Phys. Rev. Lett. 122 (2019) 191801 [arXiv:1903.09252] [INSPIRE].
LHCb collaboration, Test of lepton universality in beauty-quark decays, arXiv:2103.11769 [INSPIRE].
Muon g − 2 collaboration, Final Report of the Muon E821 Anomalous Magnetic Moment Measurement at BNL, Phys. Rev. D 73 (2006) 072003 [hep-ex/0602035] [INSPIRE].
Muon g − 2 collaboration, Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm, Phys. Rev. Lett. 126 (2021) 141801 [arXiv:2104.03281] [INSPIRE].
T. Aoyama et al., The anomalous magnetic moment of the muon in the Standard Model, Phys. Rept. 887 (2020) 1 [arXiv:2006.04822] [INSPIRE].
A. Crivellin, D. Mueller and F. Saturnino, Correlating h → μ+μ− to the Anomalous Magnetic Moment of the Muon via Leptoquarks, Phys. Rev. Lett. 127 (2021) 021801 [arXiv:2008.02643] [INSPIRE].
A. Angelescu, D. Bečirević, D.A. Faroughy, F. Jaffredo and O. Sumensari, Single leptoquark solutions to the B-physics anomalies, Phys. Rev. D 104 (2021) 055017 [arXiv:2103.12504] [INSPIRE].
T. Nomura and H. Okada, Explanations for anomalies of muon anomalous magnetic dipole moment, b → sμ\( \overline{\mu} \), and radiative neutrino masses in a leptoquark model, Phys. Rev. D 104 (2021) 035042 [arXiv:2104.03248] [INSPIRE].
D. Marzocca and S. Trifinopoulos, Minimal Explanation of Flavor Anomalies: B-Meson Decays, Muon Magnetic Moment, and the Cabibbo Angle, Phys. Rev. Lett. 127 (2021) 061803 [arXiv:2104.05730] [INSPIRE].
P.F. Perez, C. Murgui and A.D. Plascencia, Leptoquarks and matter unification: Flavor anomalies and the muon g − 2, Phys. Rev. D 104 (2021) 035041 [arXiv:2104.11229] [INSPIRE].
C. Murgui and M.B. Wise, Scalar leptoquarks, baryon number violation, and Pati-Salam symmetry, Phys. Rev. D 104 (2021) 035017 [arXiv:2105.14029] [INSPIRE].
S. Singirala, S. Sahoo and R. Mohanta, Light dark matter, rare B decays with missing energy in Lμ − Lτ model with a scalar leptoquark, Phys. Rev. D 105 (2022) 015033 [arXiv:2106.03735] [INSPIRE].
ATLAS collaboration, Searches for third-generation scalar leptoquarks in \( \sqrt{s} \) = 13 TeV pp collisions with the ATLAS detector, JHEP 06 (2019) 144 [arXiv:1902.08103] [INSPIRE].
ATLAS collaboration, Search for a scalar partner of the top quark in the all-hadronic t\( \overline{t} \) plus missing transverse momentum final state at \( \sqrt{s} \) = 13 TeV with the ATLAS detector, Eur. Phys. J. C 80 (2020) 737 [arXiv:2004.14060] [INSPIRE].
ATLAS collaboration, Search for pair production of third-generation scalar leptoquarks decaying into a top quark and a τ-lepton in pp collisions at \( \sqrt{s} \) = 13 TeV with the ATLAS detector, JHEP 06 (2021) 179 [arXiv:2101.11582] [INSPIRE].
ATLAS collaboration, Search for new phenomena in final states with b-jets and missing transverse momentum in \( \sqrt{s} \) = 13 TeV pp collisions with the ATLAS detector, JHEP 05 (2021) 093 [arXiv:2101.12527] [INSPIRE].
CMS collaboration, Search for a singly produced third-generation scalar leptoquark decaying to a τ lepton and a bottom quark in proton-proton collisions at \( \sqrt{s} \) = 13 TeV, JHEP 07 (2018) 115 [arXiv:1806.03472] [INSPIRE].
CMS collaboration, Search for heavy neutrinos and third-generation leptoquarks in hadronic states of two τ leptons and two jets in proton-proton collisions at \( \sqrt{s} \) = 13 TeV, JHEP 03 (2019) 170 [arXiv:1811.00806] [INSPIRE].
CMS collaboration, Search for singly and pair-produced leptoquarks coupling to third-generation fermions in proton-proton collisions at \( \sqrt{s} \) = 13 TeV, Phys. Lett. B 819 (2021) 136446 [arXiv:2012.04178] [INSPIRE].
ATLAS collaboration, Searches for scalar leptoquarks and differential cross-section measurements in dilepton-dijet events in proton-proton collisions at a centre-of-mass energy of \( \sqrt{s} \) = 13 TeV with the ATLAS experiment, Eur. Phys. J. C 79 (2019) 733 [arXiv:1902.00377] [INSPIRE].
ATLAS collaboration, Search for pairs of scalar leptoquarks decaying into quarks and electrons or muons in \( \sqrt{s} \) = 13 TeV pp collisions with the ATLAS detector, JHEP 10 (2020) 112 [arXiv:2006.05872] [INSPIRE].
CMS collaboration, Search for pair production of first-generation scalar leptoquarks at \( \sqrt{s} \) = 13 TeV, Phys. Rev. D 99 (2019) 052002 [arXiv:1811.01197] [INSPIRE].
CMS collaboration, Search for pair production of second-generation leptoquarks at \( \sqrt{s} \) = 13 TeV, Phys. Rev. D 99 (2019) 032014 [arXiv:1808.05082] [INSPIRE].
ATLAS collaboration, Search for pair production of scalar leptoquarks decaying into first- or second-generation leptons and top quarks in proton-proton collisions at \( \sqrt{s} \) = 13 TeV with the ATLAS detector, Eur. Phys. J. C 81 (2021) 313 [arXiv:2010.02098] [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].
A. Alloul, N.D. Christensen, C. Degrande, C. Duhr and B. Fuks, FeynRules 2.0 — A complete toolbox for tree-level phenomenology, Comput. Phys. Commun. 185 (2014) 2250 [arXiv:1310.1921] [INSPIRE].
N.D. Christensen et al., A Comprehensive approach to new physics simulations, Eur. Phys. J. C 71 (2011) 1541 [arXiv:0906.2474] [INSPIRE].
C. Degrande, C. Duhr, B. Fuks, D. Grellscheid, O. Mattelaer and T. Reiter, UFO — The Universal FeynRules Output, Comput. Phys. Commun. 183 (2012) 1201 [arXiv:1108.2040] [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].
I. Doršner and A. Greljo, Leptoquark toolbox for precision collider studies, JHEP 05 (2018) 126 [arXiv:1801.07641] [INSPIRE].
T. Sjöstrand et al., An introduction to PYTHIA 8.2, Comput. Phys. Commun. 191 (2015) 159 [arXiv:1410.3012] [INSPIRE].
M. Krämer, T. Plehn, M. Spira and P.M. Zerwas, Pair production of scalar leptoquarks at the Tevatron, Phys. Rev. Lett. 79 (1997) 341 [hep-ph/9704322] [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].
W. Beenakker, C. Borschensky, R. Heger, M. Krämer, A. Kulesza and E. Laenen, NNLL resummation for stop pair-production at the LHC, JHEP 05 (2016) 153 [arXiv:1601.02954] [INSPIRE].
I. Doršner, S. Fajfer and A. Lejlić, Novel Leptoquark Pair Production at LHC, JHEP 05 (2021) 167 [arXiv:2103.11702] [INSPIRE].
C. Borschensky, B. Fuks, A. Kulesza and D. Schwartländer, Scalar leptoquark pair production at hadron colliders, Phys. Rev. D 101 (2020) 115017 [arXiv:2002.08971] [INSPIRE].
P. Nason, A New method for combining NLO QCD with shower Monte Carlo algorithms, JHEP 11 (2004) 040 [hep-ph/0409146] [INSPIRE].
S. Frixione, P. Nason and C. Oleari, Matching NLO QCD computations with Parton Shower simulations: the POWHEG method, JHEP 11 (2007) 070 [arXiv:0709.2092] [INSPIRE].
S. Alioli, P. Nason, C. Oleari and E. Re, A general framework for implementing NLO calculations in shower Monte Carlo programs: the POWHEG BOX, JHEP 06 (2010) 043 [arXiv:1002.2581] [INSPIRE].
W. Buchmüller, R. Ruckl and D. Wyler, Leptoquarks in Lepton-Quark Collisions, Phys. Lett. B 191 (1987) 442 [Erratum ibid. 448 (1999) 320] [INSPIRE].
I. Doršner, S. Fajfer, A. Greljo, J.F. Kamenik and N. Košnik, Physics of leptoquarks in precision experiments and at particle colliders, Phys. Rept. 641 (2016) 1 [arXiv:1603.04993] [INSPIRE].
A. Angelescu, D. Bečirević, D.A. Faroughy and O. Sumensari, Closing the window on single leptoquark solutions to the B-physics anomalies, JHEP 10 (2018) 183 [arXiv:1808.08179] [INSPIRE].
O. Popov, M.A. Schmidt and G. White, R2 as a single leptoquark solution to \( {R}_{D^{\left(\ast \right)}} \) and \( {R}_{K^{\left(\ast \right)}} \), Phys. Rev. D 100 (2019) 035028 [arXiv:1905.06339] [INSPIRE].
D. Bečirević, I. Doršner, S. Fajfer, N. Košnik, D.A. Faroughy and O. Sumensari, Scalar leptoquarks from grand unified theories to accommodate the B-physics anomalies, Phys. Rev. D 98 (2018) 055003 [arXiv:1806.05689] [INSPIRE].
D. Bečirević, I. Doršner, S. Fajfer, N. Košnik, D.A. Faroughy and O. Sumensari, private communication.
K.S. Babu, P.S.B. Dev, S. Jana and A. Thapa, Unified framework for B-anomalies, muon g − 2 and neutrino masses, JHEP 03 (2021) 179 [arXiv:2009.01771] [INSPIRE].
A. Crivellin, D. Müller and F. Saturnino, Flavor Phenomenology of the Leptoquark Singlet-Triplet Model, JHEP 06 (2020) 020 [arXiv:1912.04224] [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].
A. Kulesza and L. Motyka, Threshold resummation for squark-antisquark and gluino-pair production at the LHC, Phys. Rev. Lett. 102 (2009) 111802 [arXiv:0807.2405] [INSPIRE].
A. Kulesza and L. Motyka, Soft gluon resummation for the production of gluino-gluino and squark-antisquark pairs at the LHC, Phys. Rev. D 80 (2009) 095004 [arXiv:0905.4749] [INSPIRE].
W. Beenakker, S. Brensing, M. Krämer, A. Kulesza, E. Laenen and I. Niessen, Soft-gluon resummation for squark and gluino hadroproduction, JHEP 12 (2009) 041 [arXiv:0909.4418] [INSPIRE].
W. Beenakker, S. Brensing, M. Krämer, A. Kulesza, E. Laenen and I. Niessen, Supersymmetric top and bottom squark production at hadron colliders, JHEP 08 (2010) 098 [arXiv:1006.4771] [INSPIRE].
W. Beenakker, S. Brensing, M. Krämer, A. Kulesza, E. Laenen and I. Niessen, NNLL resummation for squark-antisquark pair production at the LHC, JHEP 01 (2012) 076 [arXiv:1110.2446] [INSPIRE].
W. Beenakker et al., NNLL resummation for squark and gluino production at the LHC, JHEP 12 (2014) 023 [arXiv:1404.3134] [INSPIRE].
G.F. Sterman, Summation of Large Corrections to Short Distance Hadronic Cross-Sections, Nucl. Phys. B 281 (1987) 310 [INSPIRE].
S. Catani and L. Trentadue, Resummation of the QCD Perturbative Series for Hard Processes, Nucl. Phys. B 327 (1989) 323 [INSPIRE].
R. Bonciani, S. Catani, M.L. Mangano and P. Nason, NLL resummation of the heavy quark hadroproduction cross-section, Nucl. Phys. B 529 (1998) 424 [Erratum ibid. 803 (2008) 234] [hep-ph/9801375] [INSPIRE].
H. Contopanagos, E. Laenen and G.F. Sterman, Sudakov factorization and resummation, Nucl. Phys. B 484 (1997) 303 [hep-ph/9604313] [INSPIRE].
N. Kidonakis, G. Oderda and G.F. Sterman, Threshold resummation for dijet cross-sections, Nucl. Phys. B 525 (1998) 299 [hep-ph/9801268] [INSPIRE].
N. Kidonakis, G. Oderda and G.F. Sterman, Evolution of color exchange in QCD hard scattering, Nucl. Phys. B 531 (1998) 365 [hep-ph/9803241] [INSPIRE].
M. Beneke, P. Falgari and C. Schwinn, Threshold resummation for pair production of coloured heavy (s)particles at hadron colliders, Nucl. Phys. B 842 (2011) 414 [arXiv:1007.5414] [INSPIRE].
S. Catani, M.L. Mangano, P. Nason and L. Trentadue, The Resummation of soft gluons in hadronic collisions, Nucl. Phys. B 478 (1996) 273 [hep-ph/9604351] [INSPIRE].
J.C. Collins, F. Wilczek and A. Zee, Low-Energy Manifestations of Heavy Particles: Application to the Neutral Current, Phys. Rev. D 18 (1978) 242 [INSPIRE].
W.A. Bardeen, A.J. Buras, D.W. Duke and T. Muta, Deep Inelastic Scattering Beyond the Leading Order in Asymptotically Free Gauge Theories, Phys. Rev. D 18 (1978) 3998 [INSPIRE].
W.J. Marciano, Flavor Thresholds and Lambda in the Modified Minimal Subtraction Prescription, Phys. Rev. D 29 (1984) 580 [INSPIRE].
G. Ossola, C.G. Papadopoulos and R. Pittau, Reducing full one-loop amplitudes to scalar integrals at the integrand level, Nucl. Phys. B 763 (2007) 147 [hep-ph/0609007] [INSPIRE].
G. Ossola, C.G. Papadopoulos and R. Pittau, CutTools: A Program implementing the OPP reduction method to compute one-loop amplitudes, JHEP 03 (2008) 042 [arXiv:0711.3596] [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].
T. Hahn, Generating Feynman diagrams and amplitudes with FeynArts 3, Comput. Phys. Commun. 140 (2001) 418 [hep-ph/0012260] [INSPIRE].
H. Murayama, I. Watanabe and K. Hagiwara, HELAS: HELicity amplitude subroutines for Feynman diagram evaluations, Tech. Rep. KEK-91-11 (1992) [INSPIRE].
T. Stelzer and W.F. Long, Automatic generation of tree level helicity amplitudes, Comput. Phys. Commun. 81 (1994) 357 [hep-ph/9401258] [INSPIRE].
J. Alwall et al., MadGraph/MadEvent v4: The New Web Generation, JHEP 09 (2007) 028 [arXiv:0706.2334] [INSPIRE].
T. Hahn and M. Pérez-Victoria, Automatized one loop calculations in four-dimensions and D-dimensions, Comput. Phys. Commun. 118 (1999) 153 [hep-ph/9807565] [INSPIRE].
A. Denner, S. Dittmaier and L. Hofer, Collier: a fortran-based Complex One-Loop LIbrary in Extended Regularizations, Comput. Phys. Commun. 212 (2017) 220 [arXiv:1604.06792] [INSPIRE].
A. Denner and S. Dittmaier, Reduction of one loop tensor five point integrals, Nucl. Phys. B 658 (2003) 175 [hep-ph/0212259] [INSPIRE].
A. Denner and S. Dittmaier, Reduction schemes for one-loop tensor integrals, Nucl. Phys. B 734 (2006) 62 [hep-ph/0509141] [INSPIRE].
A. Denner and S. Dittmaier, Scalar one-loop 4-point integrals, Nucl. Phys. B 844 (2011) 199 [arXiv:1005.2076] [INSPIRE].
W. Beenakker, C. Borschensky, M. Krämer, A. Kulesza and E. Laenen, NNLL-fast: predictions for coloured supersymmetric particle production at the LHC with threshold and Coulomb resummation, JHEP 12 (2016) 133 [arXiv:1607.07741] [INSPIRE].
T.-J. Hou et al., New CTEQ global analysis of quantum chromodynamics with high-precision data from the LHC, Phys. Rev. D 103 (2021) 014013 [arXiv:1912.10053] [INSPIRE].
NNPDF collaboration, Parton distributions from high-precision collider data, Eur. Phys. J. C 77 (2017) 663 [arXiv:1706.00428] [INSPIRE].
S. Bailey, T. Cridge, L.A. Harland-Lang, A.D. Martin and R.S. Thorne, Parton distributions from LHC, HERA, Tevatron and fixed target data: MSHT20 PDFs, Eur. Phys. J. C 81 (2021) 341 [arXiv:2012.04684] [INSPIRE].
V. Hirschi, R. Frederix, S. Frixione, M.V. Garzelli, F. Maltoni and R. Pittau, Automation of one-loop QCD corrections, JHEP 05 (2011) 044 [arXiv:1103.0621] [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].
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Borschensky, C., Fuks, B., Kulesza, A. et al. Scalar leptoquark pair production at the LHC: precision predictions in the era of flavour anomalies. J. High Energ. Phys. 2022, 157 (2022). https://doi.org/10.1007/JHEP02(2022)157
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DOI: https://doi.org/10.1007/JHEP02(2022)157