Given the hints of lepton-flavour non-universality in $B$-meson decays, leptoquarks (LQs) are enjoying a renaissance. We propose novel Large Hadron Collider (LHC) searches for such hypothetical states that do not rely on strong production only, but can also receive important contributions from quark-lepton annihilation. For the cases of a resonant signal involving a bottom quark and a tau lepton ($b + τ$), a top quark and missing transverse energy ($E_{T}^{\rm miss}$) and light-flavour jets plus $E_{T}^{\rm miss}$, we develop realistic analysis strategies and provide detailed evaluations of the achievable sensitivities for the corresponding LQ signatures at future LHC runs. Our analyses allow us to derive a series of stringent constraints on the masses and couplings of third-generation singlet vector LQs, showing that at LHC Run III and the high-luminosity LHC the proposed search channels can probe interesting parts of the LQ parameter space addressing the $B$-physics anomalies. In view of the reach of the proposed $b + τ$ signature, we recommend that dedicated resonance searches for this final state should be added to the exotics search canon of both ATLAS and CMS.
We revisit scalar leptoquark pair-production at hadron colliders and significantly improve the level of precision of the cross section calculations. Apart from QCD contributions, we include lepton t-channel exchange diagrams that turn out to be relevant in the light of the recent B-anomalies. We evaluate all contributions at next-to-leading-order accuracy in QCD and resum, in the threshold regime, soft-gluon radiation at next-to-next-to-leading logarithmic accuracy. Our predictions consist hence in the most precise leptoquark cross section calculations available to date, and are necessary for …
A compilation is given of the pair production cross sections for scalar and vector leptoquarks in the kinematic range of the hadron colliders Tevatron and LHC.
$B$-physics data and flavor symmetries suggest that leptoquarks can have masses as low as few ${\cal{O}}(\mbox{TeV})$, predominantly decay to third generation quarks, and highlight $pp \to b μμ$ signatures from single production and $pp \to b b μμ$ from pair production. Abandoning flavor symmetries could allow for inverted quark hierarchies, and cause sizable $pp \to j μμ$ and $jj μμ$ cross sections, induced by second generation couplings. Final states with leptons other than muons including lepton flavor violation (LFV) ones can also arise. The corresponding couplings can also be probed by pr…
The muon-proton ($μp$) collider is an interesting option of the muon collider. Here we discuss the physics potential of the $μp$ collider; especially, leptoquarks and contact interactions. We calculate the sensitivity reach for the second generation leptoquarks and leptogluons, $R$-parity violating squarks, and $μq$ contact interactions for the $μp$ colliders of various energies and luminosities.
We examine the utility of employing polarized lepton (electron and muon) beams to perform indirect searches for scalar leptoquarks. We find that polarization can extend the reach in excluding leptoquark masses for both $e^+e^-$ and $μ^+μ^-$ machines. Polarization can also provide a diagnostic tool for determining leptoquark couplings.
A study of the production and the decay of scalar and vector leptoquarks at high-energy e+ e- colliders is presented. All tree-order contributions to single leptoquark production have been calculated and incorporated in the Monte Carlo event generator ERATO-LQ.
We estimate the future sensitivity of the high luminosity (HL-) and high energy (HE-) modes of the Large Hadron Collider (LHC) and of a 100 TeV future circular collider (FCC-hh) to leptoquark (LQ) pair production in the muon-plus-jet decay mode of each LQ. Such LQs are motivated by the fact they provide an explanation for the neutral current $B-$anomalies. For each future collider, Standard Model (SM) backgrounds and detector effects are simulated. From these, sensitivities of each collider are found. Our measures of sensitivity are based upon a Run II ATLAS search, which we also use for valid…
We discuss the physics potential of the $μp$ collider; especially, leptoquarks, leptogluons, R-parity violating squarks, contact interactions, and large extra dimensions. We calculate the sensitivity reach for these new physics at $μp$ colliders of various energies and luminosities.
Leptoquark searches are considered for future experiments at HERA, Tevatron, LHC, TESLA and THERA. Expected exclusion limits from direct leptoquark searches (leptoquark pair production and single leptoquark production) are compared with indirect limits expected from the contact interaction analysis. Strongest limits on the leptoquark masses and couplings are expected from high luminosity LHC data. If the leptoquark signal suggested by the existing data is detected at LHC, with mass below 1 TeV, TESLA will be an ideal place to study leptoquark properties, provided that the leptoquark Yukawa cou…
CMS has recently reported a moderate excess in the $μνjj$ final state in a second generation Leptoquark search, but they have disregarded it because the excess is not present in the $μμjj$ final state and because they do not observe the expected resonant peak in the distributions. As a proof of concept we show that a simple Leptoquark model including second and third generation couplings with non-negligible single- and non-resonant production in addition to usual pair production could explain the data: excess ($μνjj$), lack of excess ($μμjj$) and missing peak in the distributions; while being …
When a TeV-scale leptoquark has a sizeable Yukawa coupling, its dominant production mechanism at hadron colliders is the partonic-level lepton-quark fusion. Even though the parton distribution functions for leptons inside the proton are minuscule, they get compensated by the resonant enhancement. We present the first computation of higher order radiative corrections to the resonant leptoquark production cross section at the Large Hadron Collider (LHC). Next-to-leading (NLO) QCD and QED corrections are similar in size but come with the opposite sign. We compute NLO $K$-factors for a wide range …
We show that the current bounds on the leptoquark couplings imply that if leptoquarks are produced in e p collisions, a significant fraction of them could form a leptoquark-quark bound state. The decay of the bound state has a distinct event shape with rapidity gap. A possible application of this observation in the leptoquark search at HERA is discussed.
Recent measurements in $B \to K^{(*)} μ^+ μ^-$ decays are somewhat discrepant with Standard Model predictions. They may be harbingers of new physics at an energy scale potentially accessible to direct discovery. We estimate the sensitivity of future hadron colliders to the possible new particles that may be responsible for the anomalies: leptoquarks or $Z^\prime$s. We consider luminosity upgrades for a 14 TeV LHC, a 33 TeV LHC, and a 100 TeV $pp$ collider such as the FCC-hh. Coverage of $Z^\prime$ models is excellent: for narrow particles, with perturbative couplings that may explain the $b$-d…
A high energy muon collider can provide new and complementary discovery potential to the LHC or future hadron colliders. Leptoquarks are a motivated class of exotic new physics models, with distinct production channels at hadron and lepton machines. We study a vector leptoquark model at a muon collider with $\sqrt{s} = 3, 14$ TeV within a set of both UV and phenomenologically motivated flavor scenarios. We compute which production mechanism has the greatest reach for various values of the leptoquark mass and the coupling between leptoquark and Standard Model fermions. We find that we can probe…
We study scalar leptoquark production at TESLA and CLIC based e-gamma colliders. Both direct and resolved contributions to the cross section are examined. We find that the masses of scalar leptoquarks can be probed up to about 0.9 TeV at TESLA and 2.6 TeV at CLIC.
Leptoquarks can be produced in substantial numbers for masses very close to the collider centre of mass energy in $e^+e^-$, $eγ$, and $μ^+μ^-$ collisions due to the quark content of the photon resulting in equivalently high discovery limits. Using polarization asymmetries in an $eγ$ collider the ten different types of leptoquarks listed by Buchmüller, Rückl and Wyler can be distinquished from one another for leptoquark masses essentially up to the kinematic limit. Thus, if a leptoquark were discovered, an $eγ$ collider could play a crucial role in determining its origins.
We study pair production of leptoquarks in e+e- annihilation at linear colliders. A detailed simulation including beamstrahlung and initial state radiation, leptoquark decay and hadronization, as well as detector smearing, is performed. Discovery limits are estimated for center-of-mass energies of 500 and 800 GeV. The prospects for determining masses and couplings of leptoquarks are also investigated.
We study the signals for composite vector leptoquarks in $e^+ e^-$ colliders (LEP II, NLC, and CLIC) through their effects on the production of jet pairs, as well as their single and pair productions. We also analyze their production in $γe$ and $γγ$ collisions.
One of the most popular models that is known to be able to solve the lepton flavour universality violating charged ($b\to c$) and neutral current ($b\to s$) anomalies is the Leptoquark Model. In this work we examine the {\it multijet} + $\mET$ collider signature of a vector leptoquark ($U_1$) which has the potential to mediate both the charged and neutral current processes at tree level. From our collider analysis we derive the exclusion limits on mass for the $U_1$ leptoquark at 95\% C.L. at the current and future experiment of the Large Hadron Collider. We also calculate the effect of such a…
The pair production cross section for scalar and vector leptoquarks at $ep$ colliders is calculated for the case of photon--gluon fusion. In a model independent analysis we consider the most general $C$ and $P$ conserving couplings of gluons and photons to both scalar and vector leptoquarks described by an effective low--energy Lagangian which obeys $U(1)_{em} \times SU(3)_c$ invariance. Numerical predictions are given for the kinematical regime at HERA and LEP~$\otimes$~LHC.
The resolved and direct photon contributions to the single leptoquark (L) production process $γp\rightarrow L e$ are analysed for both scalar (S) and vector (V) leptoquarks in detail. It is shown that resolved photon contribution dominates for $M_{L}\leq 300 GeV$. For $M_{V}\geq 1 TeV$ and $M_{S}\geq 0.5 TeV$ cross section is completely determined by the direct photon conribution. The vector leptoquarks are discussed for both gauge- and non-gauge cases seperately.
We present a comprehensive review of physics effects generated by leptoquarks (LQs), i.e., hypothetical particles that can turn quarks into leptons and vice versa, of either scalar or vector nature. These considerations include discussion of possible completions of the Standard Model that contain LQ fields. The main focus of the review is on those LQ scenarios that are not problematic with regard to proton stability. We accordingly concentrate on the phenomenology of light leptoquarks that is relevant for precision experiments and particle colliders. Important constraints on LQ interactions wi…
We study the effects of virtual leptoquark exchange on charged current and neutral current processes at HERA, on di-lepton production at the Tevatron, and on quark pair production at LEP II. We present the areas of parameter space that can be excluded at these colliders by searching for deviations from Standard Model expectations.
We investigate the possibility of detecting a scalar leptoquark, coupling to the electron and the top, at a linear collider. For coupling strength equalling the weak coupling constant, the present mass bounds are of the order of 300 GeV. We demonstrate that at the NLC, one could detect such particles if their mass were less than a few TeV's.
The search reaches for both scalar($S$) and vector($V$) leptoquarks at future hadron colliders are summarized. In particular we evaluate the production cross sections of both leptoquark types at TeV33 and LHC as well as the proposed 60 and 200 TeV colliders through both quark-antiquark annihilation and gluon-gluon fusion: $q \bar q, gg \to SS,VV$. Experiments at these machines should easily discover such particles if their masses are not in excess of the few TeV range. [To appear in the Proceedings of the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics-Snowmass96, Snowmass,…
Leptoquarks can be produced in pairs by gluon--gluon fusion and quark--antiquark annihilation at hadron colliders. While HERA is the proper machine for single production of $(eu)$ and $(ed)$ type leptoquarks, the flavor species of ($μu$), ($μd$) and ($τu$), ($τd$) type leptoquarks can be produced at hadron colliders very efficiently. Besides exploiting gluon-quark collisions, leptoquarks can also be produced singly by colliding the quarks in one proton beam with leptons $e,μ,τ$ generated by splitting photons which are radiated off the quarks in the other proton beam. For Yukawa couplings of th…
While the hunt for new states beyond the standard model (SM) goes on for various well motivated theories, the leptoquarks are among the most appealing scenarios at recent times due to a series of tensions observed in $B$-meson decays. We consider $SU(2)$ singlet and triplet scalar leptoquarks separately, which contribute to charged and neutral current $B$-meson decays. Focusing on the single production of these two scalar leptoquarks, we perform a PYTHIA-based simulation considering all the dominant SM backgrounds at the current and future setups of the Large Hadron Collider (LHC). The mono-$b…
Collider searches for first-, second-, and third-generation scalar (S) or vector (V) leptoquarks (LQs) focus on the quark-lepton decay modes S,V -> q l. For SU(2)-doublet and -triplet leptoquarks with a sufficiently large splitting between the components, decays involving real W-boson emission (such as S_2^{(+5/3)} -> S_2^{(+2/3)} W^{+} and others) become possible and can change the patterns of leptoquark decays. For third-generation leptoquarks, where these mass splittings might be large, such modes could dominate certain leptoquark decays as they are (if kinematically allowed) guaranteed to …
Though various extensions of the Standard Model with higher gauge group predict the existence of leptoquarks, none of them has been observed yet at any of the colliders. In this paper, we study the prospect of several past and future $e$-$p$ colliders like HERA, LHeC and FCC-he to detect them through radiation amplitude zero. We find that the leptoquarks showing zeros in the tree-level single-photon amplitudes at $e$-$p$ collider lie within the complementary set of those exhibiting zeros at $e$-$γ$ collider. We present a PYTHIA-based analysis for HERA, LHeC and FCC-he (run II) to detect the le…
In this report we study how a light-scalar leptoquark could affect the Higgs boson production cross-section at the LHC collider. We construct the most general renormalizable and gauge invariant effective Lagrangian involving the standard model particles and a scalar, isoscalar leptoquark, η. The total cross-section for pp -> H+X is then calculated for different values of the unknown parameters λ_eta, m_eta and m_H.(Here λ_eta is the coupling associated with the Higgs-leptoquark interaction.) We find that if λ_eta is moderately large and m_eta is around a few hundred GeV, then the cross-section…
We explore the production of vector leptoquarks ($V$) at the Tevatron, LHC, and SSC through both quark-antiquark and gluon fusion: $q \bar q, gg \to VV$. The cross sections are found to be somewhat larger than for scalar leptoquarks of the same mass implying enhanced search capabilities. Contributed to the Workshop on Physics at Current Accelerators and the Supercollider, Argonne National Lab, June 1993.
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 ($p p \to ΦΦ$) and (ii) single LQ + lepton production ($p p \to Φ\ell$) for all initial quark flavours ($u$, $d$, $s$, $c$, and $b$). Vector LQ …
The cross section of single vector leptoquark production in direct lepton-gluon interaction is calculated. In a model independent analysis an effective Lagrangian describing the most general $C$ and $P$ conserving coupling of the leptoquarks to gluons is considered. An analytical expression is derived for the cross section in the case of anomalous vector leptoquark couplings to the gluon field. The cross sections of inclusive production of ($eq$)-, ($μq$)- and ($τq$)-type vector leptoquarks in $ep$ and $pp$ collisions due to direct lepton-gluon interaction are evaluated for $q=u, b, t$. Depend…
The LHCb Collaboration recently gave an update on testing lepton flavour universality with $B^+ \rightarrow K^+ \ell^+ \ell^-$, in which a 3.1 standard deviations from the standard model prediction was observed. The g-2 experiment also reports a 3.3 standard deviations from the standard model on muon anomalous magnetic moment measurement. These deviations could be explained by introducing new particles including leptoquarks. In this paper, we show the possibility to search for heavy spin-1 leptoquarks at a future TeV scale muon collider by performing studies from three channels: 1) same flavou…
We study leptoquark production using polarized $eγ$ colliders for the center of mass energies $\sqrt s=500$~GeV and 1~TeV. We show that using polarization asymmetries the ten different types of leptoquarks listed by Buchmüller, Rückl and Wyler can be distinquished from one another for leptoquark masses essentially up to the kinematic limit of the respective colliders. Thus, if a leptoquark were discovered an $eγ$ collider could play a crucial role in determining its origins.
Leptoquarks are one of the possible candidates for explaining various anomalies in flavour physics. Nonetheless, their existence is yet to be confirmed from experimental side. In this paper we have shown how zeros of single photon tree-level amplitude can be used to extract information about leptoquarks in case of $e$-$γ$ colliders. Small number of standard model backgrounds keep the signal clean in this kind of colliders. Unlike other colliders, the zeros of single photon amplitude here depend on $\sqrt{s}$ as well as the mass of leptoquark along with its electric charge. We perform a PYTHIA …
The Leptoquark model has been instrumental in explaining the observed lepton flavour universality violating charged ($b\to c$) and neutral ($b\to s$) current anomalies that have been the cause for substantial excitement in particle physics recently. In this article we have studied the role of one (designated as $V_2^{\frac 43}$) of the components of {\boldmath${V}_2$} Vector Leptoquark doublet with electromagnetic charge $\frac 43$ in explaining the neutral current ($b\to s$) anomalies $R_{K^{(*)}}$ and $B_s\toμ^+μ^-$. Moreover, we have performed a thorough collider search for this $V_2^{\frac…
In this talk I summarize the capability of future lepton colliders to discover leptoquarks and to determine their electroweak quantum numbers. This analysis is an updated discussion based on the results presented in the Snowmass 1996 New Phenomena Working Group report as well as some more recent work that has appeared in the literature as a result of the HERA high-$Q^2$ excess.
We study the sensitivity of the Tevatron and the 7 TeV LHC to a leptoquark S coupling to a top quark and a charged lepton L (= e, mu, or tau). For the Tevatron, we focus on the case m_S < m_t, where the leptoquark pair production cross section is large, and the decay is three-body: S --> W b L^{\pm}. We argue that existing Tevatron observations could exclude m_S \lsim 160 GeV. For m_S > m_t, we show that the LHC experiments with low integrated luminosity could be sensitive to such leptoquarks decaying to tl^{\pm} with l= mu or tau.
We consider single production of leptoquarks (LQ's) at $eγ$ colliders, for two values of the centre-of-mass energy, $\sqrt{s}=500$ GeV and 1 TeV. LQ's with masses essentially up to the kinematic limit can be seen, even for couplings as weak as $O(10^{-3})$-$O(10^{-2})α_{em}$. It is possible to detect LQ's of mass greater than $\sqrt{s}$ by looking for signals of virtual LQ production in $eγ\to e q{\overline q}$.
We study single leptoquark production in $e^+e^-$, $eγ$, and $μ^+μ^-$ collisions due to the quark content of the photon. Leptoquarks can be produced in substantial numbers for masses very close to the centre of mass energy of the collider which results in equivalently high discovery limits. Using polarization asymmetries in an $eγ$ collider the ten different types of leptoquarks listed by Buchmüller, Rückl and Wyler can be distinquished from one another for leptoquark masses essentially up to the kinematic limit. Thus, if a leptoquark were discovered an $eγ$ collider could play a crucial role …
We study limits from dilepton searches on leptoquark completions to the Standard Model in the parameter space motivated by anomalies in the $b \rightarrow s$ sector. After a full Run-2 analysis by LHCb, the disparity in lepton flavour violation has disappeared. However, the mismatch in angular distributions as well as in $B_s \rightarrow μ^+ μ^-$ partial width is still unresolved and still implies a possible new physics contribution. We probe three models of leptoquarks -- scalar models $S_3$ and $R_2$ as well as vector leptoquark model $U_1$ using non-resonant dilepton searches to place limit…
We perform a model independent analysis of the production of scalar and vector leptoquarks in the $e^-γ$ mode of a linear collider of the next generation. Since these leptoquarks are produced singly, higher masses can be probed than in other collider modes, like $e^+e^-$ scattering. We discuss the discovery potential and show how polarization and angular distributions can be used to distinguish between the different types of leptoquarks.
Theoretical predictions for the production cross sections of leptoquarks at the CERN LHC are presented including higher-order QCD corrections. These corrections reduce the dependence on the renormalization/factorization scales significantly. Moreover, they are required to exploit the leptoquark mass reach of the LHC experiments. In this sequel to an earlier analysis performed for the Tevatron collider we extend the leptoquark analysis to the LHC energy.
Recent progress in calculating lepton density functions inside the proton and simulating lepton showers laid the foundations for precision studies of resonant leptoquark production at hadron colliders. Direct quark-lepton fusion into a leptoquark is a novel production channel at the LHC that has the potential to probe a unique parameter space for large masses and couplings. In this work, we build the first Monte Carlo event generator for a full-fledged simulation of this process at NLO for production, followed by a subsequent decay using the POWHEG method and matching to the parton showers uti…
We perform a systematic analysis of scalar and vector leptoquark pair production at the Fermilab Tevatron and at the CERN LHC. We evaluate signal expectations and background levels for the processes pp (p ppar) -> 2 jets + e^{+} + e^{-} and 2 jets + e + missing p_T. The Monte Carlo event generator ISAJET is used to simulate the experimental conditions at the current (Sqrt{s}=1.8 TeV, Luminosity=100 pb^{-1}) and upgraded (Luminosity=100 pb^{-1}) Tevatron as well as the LHC (Sqrt{s}=14 TeV, Luminosity=10 fb^{-1}). Depending on the luminosity, and assuming a branching ratio B(LQ -> eq)=0.5, we fi…
Observation of a sequence of resonances at an e-e- collider would suggest bound states of strongly coupled constituents carrying lepton number. Obvious candidates for these exotic constituents are leptoquarks and leptogluons. We show that under reasonable assumptions, the existence of one leptogluon flavor of appropriate mass can give rise to sizeable ``leptoglueball'' production rates and observable resonance peaks. In contrast, one needs two leptoquark flavors in order to produce the analogous ``leptoquarkonium'' states. Moreover, cross-generational leptoquark couplings are necessary to give…
We consider single production of leptoquarks (LQ's) at $e^+e^-$ and $γγ$ colliders, for two values of the centre-of-mass energy, $\sqrt{s}=500$ GeV and 1 TeV. We find that LQ's which couple within the first generation are observable for LQ masses almost up to the kinematic limit, both at $e^+e^-$ and $γγ$ colliders, for the LQ coupling strength equal to $α_{em}$. The cross sections for single production of $2^{nd}$- and $3^{rd}$-generation LQ's at $e^+e^-$ colliders are too small to be observable. In $γγ$ collisions, on the other hand, $2^{nd}$-generation LQ's with masses much larger than $\sq…
We study implications of large lepton-quark-leptoquark couplings for direct leptoquark searches at Large Hadron Collider. We present all existing flavor constraints on the strength of these couplings assuming that leptoquarks under consideration interact exclusively with charged leptons and quarks of the same generation. We find that these leptoquarks can have sizeable couplings to the Standard Model fermions. This insures a self consistency of our study. We discuss the leptoquark production mechanisms at LHC and demonstrate the importance of inclusion of a t-channel pair production and, in pa…
Anomalies in recent LHCb, Belle and Babar measurements of $R_{D^{(*)}}$, and $R_{K^{(*)}}$ in $B$ decays may indicate the new physics beyond the Standard Model (SM). The leptoquarks ($LQ$) that couple to the $3^{\mathrm{rd}}$ generation quarks and leptons have been proposed as a viable new physics (NP) explanation. Such left-handed $LQ$s can couple to both bottom and top quarks. Since top particles decay before the hadronization, it is possible to reconstruct chirality of boosted top quarks and consequently the chirality of top coupling to the $LQ$s. We perform analysis on the top quark's chir…
Despite the immense success of the Standard Model, the hunt for physics beyond the Standard Model has continued. Extension of the SM gauge group or the particle content of the SM remains a viable solution to many observed anomalies, such as the anomalous magnetic moment of muon, flavor violation, dark matter, etc. In this work, we consider a BSM model which includes a leptoquark, a vector-like lepton, and a real scalar singlet. The model accounts for a dark matter candidate through a $\mathbb{Z}_2$ symmetry in addition to predicting the muon $(g-2)$ in agreement with the experimental measureme…
The single production of leptoquarks in $e^+e^-$, $eγ$ and $γγ$ linear colliders is discussed. We show that these new particles could be seen in such machines even if their mass is close to the kinematic limit. (Invited talk given by G.B. at the ``Workshop on Physics and Experiments at Linear $e^+e^-$ Colliders'', Waikoloa, Hawaii, April 26-30, 1993.)
In this article we perform a combined analysis of low energy precision constraints and LHC searches for leptoquarks which couple to first generation fermions. Considering all ten leptoquark representations, five scalar and five vector ones, we study at the precision frontier the constraints from $K\toπνν$, $K\toπe^+e^-$, $K^0-\bar K^0$ and $D^0-\bar D^0$ mixing, as well as from experiments searching for parity violation (APV and QWEAK). We include LHC searches for $s$-channel single resonant production, pair production and Drell-Yan-like signatures of leptoquarks. Interestingly, we find that t…
We calculate the resolved photon contribution to leptoquark production at $eγ$ colliders for the center of mass energies $\sqrt s=500$~GeV and 1~TeV. We also calculate the resolved photon contribution to leptoquark production at $e^+ e^-$ colliders for the center of mass energies $\sqrt{s} = 1$~and~2~TeV. In both cases we find that these contributions are considerably larger than the standard contributions considered in the literature.
The scalar and vector leptoquark pair production cross sections in hadronic collisions are calculated. In a model independent analysis we consider the most general C and P conserving couplings of gluons to both scalar and vector leptoquarks described by an effective low--energy Lagangian which obeys SU(3)_c invariance. Analytrical expressions are derived for the differential and integral scattering cross sections including the case of anomalous vector leptoquark couplings, $κ_G$ and $λ_G$, to the gluon field. Numerical predictions are given for the kinematic range of the TEVATRON and LHC. The …
We investigate the ability of the $S_3$ scalar leptoquark to address the recent hints of lepton universality violation in $B$ meson decays. The $S_3$ leptoquark with quantum numbers $(\overline{\mathbf{3}},\mathbf{3},1/3)$ naturally emerges in the context of an $SU(5)$ GUT model without any conflict with the stringent limits from observed nucleon stability. Scalar leptoquark $S_3$ with left-handed couplings to 2nd and 3rd generations of charged leptons and down-type quarks seems well-suited to address both $R_{K^{(*)}}$ and $R_{D^{(*)}}$. We quantify this suitability with numerical fits to a p…
