Search

Abstract A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work.

We assess the complementarity between colliders, direct detection searches, and gravitational wave interferometry in probing a scenario of dark matter in the early universe. The model under consideration contains a B−L gauge symmetry and a vector-like fermion which acts as the dark matter candidate. The fermion induces significant a large dark matter-nucleon scattering rate, and the Z′ field produces clear dilepton events at colliders. Thus, direct detection experiments and colliders severely constrain the parameter space in which the correct relic density is found in agreement with the data. Nevertheless, little is known about the new scalar responsible for breaking the B-L symmetry. If this breaking occurs via a first-order phase transition at a TeV scale, it could lead to gravitational waves in the mHz frequency range detectable by LISA, DECIGO, and BBO instruments. The spectrum is highly sensitive to properties of the scalar sector and gauge coupling. We show that a possible GW detection, together with information from colliders and direct detection experiments, can simultaneously pinpoint the scalar self-coupling, and narrow down the dark matter mass where a thermal relic is viable.

Abstract The Hubble constant inferred from the 6-parameter fit to the CMB power spectrum conflicts with the value obtained from direct measurements via type Ia supernova and Cepheids observations. We write down effective operators involving spin-0, spin-1/2, and spin-1 dark matter that lead to the relativistic production of dark matter particles at early times, and consequently lead to an increase in the number of relativistic degrees of freedom. This mechanism which is amenable to CMB, BBN, and structure formation observables can sufficiently raise the value of the Hubble constant derived from CMB and reconcile local and CMB probes of the Hubble constant. This mechanism alone increases $$H_0$$ H 0 up to $$70\, \textrm{km}\, \textrm{s}^{-1} \, \textrm{Mpc}^{-1}$$ 70 km s - 1 Mpc - 1 , and with the help of a Phantom-like cosmology, reach $$H_0 \simeq $$ H 0 ≃ 71–73 $$\textrm{km} \,\textrm{s}^{-1} \textrm{Mpc}^{-1}$$ km s - 1 Mpc - 1 . Lastly, we outline the region of parameter space which reproduces $$H_0 \simeq $$ H 0 ≃ 71–73 $$\textrm{km} \,\textrm{s}^{-1} \, \textrm{Mpc}^{-1}$$ km s - 1 Mpc - 1 while obeying all relevant constraints.

Abstract We discuss a model where a mixed warm and hot keV neutrino dark matter rises naturally. We arrange active and sterile neutrinos in the same SU(3) L multiplet, with the lightest sterile neutrino being dark matter. The other two heavy sterile neutrinos, through their out-of-equilibrium decay, contribute both to the dilution of dark matter density and its population, after freeze-out. We show that this model features all ingredients to overcome the overproduction of keV neutrino dark matter, and explore the phenomenological implications for Big Bang Nucleosynthesis and the number of relativistic degrees of freedom.

The Muon g-2 experiment at FERMILAB has confirmed the muon anomalous magnetic moment anomaly, with an error bar 15% smaller and a different central value compared with the previous Brookhaven result. The combined results from FERMILAB and Brookhaven show a difference with theory at a significance of 4.2σ, strongly indicating the presence of new physics. In light of this new result, we discuss a Two Higgs Doublet model augmented by an Abelian gauge symmetry that can simultaneously accommodate a light dark matter candidate and (g−2)μ, in agreement with existing bounds.

Motivated by the recent muon anomalous magnetic moment (g-2) measurement at FERMILAB and non-zero neutrino masses, we propose a model based on the SU(3)C×SU(3)L×U(1)X (3-3-1) gauge symmetry. The most popular 3-3-1 models in the literature require the presence of a scalar sextet to address neutrino masses. In our work, we show that we can successfully implement an one-loop linear seesaw mechanism with right-handed neutrinos, and vector-like fermions to nicely explain the active neutrino masses, and additionally reproduce the recent Muon g-2 result, in agreement with existing bounds.

Since the heavy neutrinos of the inverse seesaw mechanism mix largely with the standard ones, the charged currents formed with them and the muons have the potential of generating robust and positive contribution to the anomalous magnetic moment of the muon. However, bounds from the non-unitary in the leptonic mixing matrix may restrict so severely the parameters of the mechanism that, depending on the framework under which the mechanism is implemented, may render it unable to explain the recent muon g-2 result. In this paper we show that this happens when we implement the mechanism into the standard model and into two versions of the 3-3-1 models.

Abstract Neutrinos are massless in the Standard Model. The most popular mechanism to generate neutrino masses are the type I and type II seesaw, where right-handed neutrinos and a scalar triplet are augmented to the Standard Model, respectively. In this work, we discuss a model where a type I + II seesaw mechanism naturally arises via spontaneous symmetry breaking of an enlarged gauge group. Lepton flavor violation is a common feature in such setup and for this reason, we compute the model contribution to the $$\mu \rightarrow e\gamma $$ μ→eγ and $$\mu \rightarrow 3e$$ μ→3e decays. Moreover, we explore the connection between the neutrino mass ordering and lepton flavor violation in perspective with the LHC, HL-LHC and HE-LHC sensitivities to the doubly charged scalar stemming from the Higgs triplet. Our results explicitly show the importance of searching for signs of lepton flavor violation in collider and muon decays. The conclusion about which probe yields stronger bounds depends strongly on the mass ordering adopted, the absolute neutrino masses and which much decay one considers. In the 1–5 TeV mass region of the doubly charged scalar, lepton flavor violation experiments and colliders offer orthogonal and complementary probes. Thus if a signal is observed in one of the two new physics searches, the other will be able to assess whether it stems from a seesaw framework.

Motivated by the interesting features of Two Higgs Doublet Models (2HDM) we present a 2HDM extension where the stability of dark matter, neutrino masses and the absence of flavor changing interactions are explained by promoting baryon and lepton number to gauge symmetries. Neutrino masses are addressed within the usual type I seesaw mechanism. A vector-like fermion acts as dark matter and it interacts with Standard Model particles via the kinetic and mass mixings between the neutral gauge bosons. We compute the relevant observables such as the dark matter relic density and spin-independent scattering cross section to outline the region of parameter space that obeys current and projected limits from collider and direct detection experiments via thermal and non-thermal dark matter production.

2-Higgs Doublet Models (2HDMs) typically need to invoke an ad-hoc discrete symmetry to avoid severe flavor bounds and in addition feature massless neutrinos, thus falling short of naturally complying with existing data. However, when augmented by an Abelian gauge symmetry naturally incorporating neutrino masses via a type-I seesaw mechanism while at the same time escaping flavor changing interactions, such enlarged 2HDMs become very attractive phenomenologically. In such frameworks, the distinctive element is the Z′ gauge boson generated by the spontaneous breaking of the Abelian group U(1)X. In this work, we derive updated collider bounds on it. Several theoretical setups are possible, each with different and sometimes suppressed couplings to quarks and leptons. Thus, complementary data from dijet and dilepton resonance searches need to be considered to fully probe these objects. We employ the corresponding datasets as obtained at the Large Hadron Collider (LHC) at the 13 TeV CMs energy for L=12, 36 and 300 fb−1 of luminosity. Moreover, we present the potential sensitivity to such Z′s of the High Luminosity LHC (HL-LHC) and High Energy LHC (HE-LHC).

Abstract General Two Higgs Doublet Models (2HDM) are popular Standard Model extensions but feature flavor changing interactions and lack neutrino masses. We discuss a 2HDM where neutrino masses are generated via type I seesaw and propose an extension where neutrino masses are generated via a type II seesaw mechanism with flavor changing interactions being absent via the presence of a U(1) gauge symmetry. After considering a variety of bounds such as those rising from collider and electroweak precision we show that our proposal stands as a UV complete 2HDM with a dark photon where neutrino masses and flavor changing interactions are addressed. A possible dark matter realization is also discussed.

Analyzing the neutrino Yukawa effect in the freeze-out process of a generic dark matter candidate with right-handed neutrino portal, we identify the parameter regions satisfying the observed dark matter relic density as well as the current Fermi-LAT and H.E.S.S. limits and the future CTA reach on gamma-ray signals. In this scenario the dark matter couples to the Higgs boson at one-loop level and thus could be detected by spin-independent nucleonic scattering for a reasonable range of the relevant parameters. Keywords: Right-handed neutrino, Dark matter, Direct and indirect detection

Abstract We consider tritium beta decay with additional emission of light pseudoscalar or vector bosons coupling to electrons or neutrinos. The electron energy spectrum for all cases is evaluated and shown to be well estimated by approximated analytical expressions. We give the statistical sensitivity of Katrin to the mass and coupling of the new bosons, both in the standard setup of the experiment as well as for future modifications in which the full energy spectrum of tritium decay is accessible.

Currently, the standard cosmological model faces some tensions and discrepancies between observations at early and late cosmological time. One of them concerns the well-known H0-tension problem, i.e., a ∼4.4σ-difference between the early-time estimate and late-time measurements of the Hubble constant, H0. Another puzzling question rests in the cosmological lithium abundance, where again local measurements differ from the one predicted by Big Bang Nucleosynthesis (BBN). In this work, we show that a mechanism of light dark matter production might hold the answer for these questions. If dark matter particles are sufficiently light and a fraction of them were produced non-thermally in association with photons, this mechanism has precisely what is needed to destroy Lithium without spoiling other BBN predictions. Besides, it produces enough radiation that leads to a larger H0 value, reconciling early and late-time measurements of the Hubble expansion rate without leaving sizable spectral distortions in the Cosmic Microwave Background spectrum.

Motivated by the low-energy electron recoil spectrum observed by the dark matter experiment, XENON1T, at Gran Sasso laboratory, we interpret the observed signal not in terms of a dark matter particle, but rather in the context of a new light Z′ gauge boson. We discuss how such a light Z′ emerges in a Two Higgs Doublet Model augmented by an abelian gauge symmetry where neutrino masses and the flavor problem are addressed, in agreement with neutrino-electron scattering data.

We have witnessed a persistent puzzling anomaly in the muon magnetic moment that cannot be accounted for in the Standard Model even considering the existing large hadronic uncertainties. A new measurement is forthcoming, and it might give rise to a 5σ claim for physics beyond the Standard Model. Motivated by it, we explore the implications of this new result to five models based on the SU(3)C×SU(3)L×U(1)N gauge symmetry and put our conclusions into perspective with LHC bounds. We show that previous conclusions found in the context of such models change if there are more than one heavy particle running in the loop. Moreover, having in mind the projected precision aimed by the g-2 experiment at FERMILAB, we place lower mass bounds on the particles that contribute to muon anomalous magnetic moment assuming the anomaly is otherwise resolved. Lastly, we discuss how these models could accommodate such anomaly in agreement with current bounds.

Atomic Parity Violation (APV) is usually quantified in terms of the weak nuclear charge QW of a nucleus, which depends on the coupling strength between the atomic electrons and quarks. In this work, we review the importance of APV to probing new physics using effective field theory. Furthermore, we correlate our findings with the results from neutrino-nucleus coherent scattering. We revisit signs of parity violation in polarized electron scattering and show how precise measurements on the Weinberg's angle give rise to competitive bounds on light mediators over a wide range of masses and interactions strengths. Our bounds are firstly derived in the context of simplified setups and then applied to several concrete models, namely Dark Z, Two Higgs Doublet Model-U(1)X and 3-3-1, considering both light and heavy mediator regimes.

Motivated by the recent result of XENON1T collaboration with full exposure, 279 life days, that sets the most stringent limit on the spin-independent dark matter-nucleon scattering cross section we discuss a dark E6-inspired model that features the presence of a U(1)d−u gauge symmetry. The dark matter candidate is a Dirac fermion that interacts with Standard Model fermions via a massive Z′ that preserves the quantum number assignments of this symmetry. We compute the spin-independent scattering cross section off xenon nucleus and compare with the XENON1T limit; find the LHC bound on the Z′ mass as well as the projection sensitivity of high-energy and luminosity LHC; and derive the Fermi-LAT bounds on the dark matter annihilation cross section based on the observation of gamma-rays in the direction of Dwarf Spheroidal galaxies. We exploit the complementarity between these datasets to conclude that the new bound from XENON1T severely constrain the model, which combined with the LHC upgrade sensitivity rules out this WIMP realization setup below 5 TeV.

We investigate the dark matter phenomenology of a Dirac fermion together with kinetic mixing in the context of an Lμ−Lτ model. We analyze which part of the parameter space can provide a viable dark matter candidate and explain the B-decay anomaly, while obeying current data. Although the allowed region of parameter space, satisfying these requirements, is still large at the moment, future direct detection experiments like XENONnT and DARWIN will, in case of null results, significantly strengthen the limits and push the model to a corner of the parameter space.

Abstract We study the framework of U(1) X models with kinetic mixing and/or mass mixing terms. We give general and exact analytic formulas of fermion gauge interactions and the cross sections of neutrino-electron scattering in such models. Then we derive limits on a variety of U(1) X models that induce new physics contributions to neutrino-electron scattering, taking into account interference between the new physics and Standard Model contributions. Data from TEXONO, CHARM-II and GEMMA are analyzed and shown to be complementary to each other to provide the most restrictive bounds on masses of the new vector bosons. In particular, we demonstrate the validity of our results to dark photon-like as well as light Z ′ models.

Abstract We propose a model which unifies the Left-Right symmetry with the SU(3) L gauge group, called flipped trinification, and based on the SU(3) C ⊗ SU(3) L ⊗ SU(3) R ⊗ U(1) X gauge group. The model inherits the interesting features of both symmetries while elegantly explaining the origin of the matter parity, W P = (−1)3(B−L)+2s , and dark matter stability. We develop the details of the spontaneous symmetry breaking mechanism in the model, determining the relevant mass eigenstates, and showing how neutrino masses are easily generated via the seesaw mechanism. Moreover, we introduce viable dark matter candidates, encompassing a fermion, scalar and possibly vector fields, leading to a potentially novel dark matter phenomenology.

Abstract Weakly Interacting Massive Particles (WIMPs) are among the best-motivated dark matter candidates. No conclusive signal, despite an extensive search program that combines, often in a complementary way, direct, indirect, and collider probes, has been detected so far. This situation might change in near future due to the advent of one/multi-TON Direct Detection experiments. We thus, find it timely to provide a review of the WIMP paradigm with focus on a few models which can be probed at best by these facilities. Collider and Indirect Detection, nevertheless, will not be neglected when they represent a complementary probe.

A puzzling excess in gamma-rays at GeV energies has been observed in the center of our galaxy using Fermi-LAT data. Its origin is still unknown, but it is well fitted by Weakly Interacting Massive Particles (WIMPs) annihilations into quarks with a cross section around 10â26Â cm3sâ1 with masses of 20â50 GeV, scenario which is promptly revisited. An excess favoring similar WIMP properties has also been seen in anti-protons with AMS-02 data potentially coming from the Galactic Center as well. In this work, we explore the possibility of fitting these excesses in terms of semi-annihilating dark matter, dubbed as semi-Hooperon, with the process WIMPWIMPâWIMPX being responsible for the gamma-ray excess, where X=h,Z. An interesting feature of semi-annihilations is the change in the relic density prediction compared to the standard case, and the possibility to alleviate stringent limits stemming from direct detection searches. Moreover, we discuss which models might give rise to a successful semi-Hooperon setup in the context of Z3,Z4 and extra âdarkâ gauge symmetries.

Abstract It was recently pointed out that direct detection signals from at least three different targets may be used to determine whether the Dark Matter (DM) particle is different from its antiparticle. In this work, we examine in detail the feasibility of this test under different conditions, motivated by proposals for future detectors. Specifically, we perform likelihood fits to mock data under the hypotheses that the DM particle is identical to or different from its antiparticle, and determine the significance with which the former can be rejected in favor of the latter. In our analysis, we consider 3 different values of the DM mass (50 GeV, 300 GeV, 1 TeV) and 4 different experimental ensembles, each consisting of at least 3 different targets — Xe and Ar plus one among the following: Si, Ge, CaWO4, or Ge/CaWO4. For each of these experimental ensembles and each DM mass, the expected discrimination significance is calculated as a function of the DM-nucleon couplings. In the best case scenario, the discrimination significance can exceed O 3 σ $$ \mathcal{O}\left(3\sigma \right) $$ for three of the four ensembles considered, reaching O 5 σ $$ \mathcal{O}\left(5\sigma \right) $$ at special values of the DM-nucleon couplings. For the ensemble including Si, O 5 σ $$ \mathcal{O}\left(5\sigma \right) $$ significance can be achieved for a range of DM masses and over a much wider range of DM-nucleon couplings, highlighting the need for a variety of experimental targets in order to determine the DM properties. These results show that future direct detection signals could be used to exclude, at a statistically significant level, a Majorana or a real DM particle, giving a critical clue about the identity of the Dark Matter.

We discuss a non-supersymmetric scenario which addresses the origin of the matter-parity symmetry, PM=(−1)3(B−L)+2s, leading to a viable Dirac fermion dark matter candidate. Implications to electroweak precision, muon anomalous magnetic moment, flavor changing interactions, lepton flavor violation, dark matter and collider physics are discussed in detail. We show that this non-supersymmetric model is capable of generating the matter-parity symmetry in agreement with existing data with gripping implications to particle physics and cosmology.

Grand Unified Theories (GUT) offer an elegant and unified description of electromagnetic, weak and strong interactions at high energy scales. A phenomenological and exciting possibility to grasp GUT is to search for TeV scale observables arising from Abelian groups embedded in GUT constructions. That said, we use dilepton data (ee and μμ) that has been proven to be a golden channel for a wide variety of new phenomena expected in theories beyond the Standard Model to probe GUT-inspired models. Since heavy dilepton resonances feature high signal selection efficiencies and relatively well-understood backgrounds, stringent and reliable bounds can be placed on the mass of the Z′ gauge boson arising in such theories. In this work, we obtain 95% C.L. limits on the Z′ mass for several GUT-models using current and future proton–proton colliders with s=13 TeV,33 TeV,and100 TeV, and put them into perspective with dark matter searches in light of the next generation of direct detection experiments.

Abstract Baryon and lepton numbers being accidental global symmetries of the Standard Model (SM), it is natural to promote them to local symmetries. However, to preserve anomaly-freedom, only combinations of B–L are viable. In this spirit, we investigate possible dark matter realizations in the context of the $$U(1)_\mathrm{B{-}L}$$ U ( 1 ) B - L model: (i) Dirac fermion with unbroken B–L; (ii) Dirac fermion with broken B–L; (iii) scalar dark matter; (iv) two-component dark matter. We compute the relic abundance, direct and indirect detection observables and confront them with recent results from Planck, LUX-2016, and Fermi-LAT and prospects from XENON1T. In addition to the well-known LEP bound $$M_{Z^{\prime }}/g_\mathrm{BL} \gtrsim 7$$ M Z ′ / g BL ≳ 7 TeV, we include often ignored LHC bounds using 13 TeV dilepton (dimuon + dielectron) data at next-to-leading order plus next-to-leading logarithmic accuracy. We show that, for gauge couplings smaller than 0.4, the LHC gives rise to the strongest collider limit. In particular, we find $$M_{Z^{\prime }}/g_\mathrm{BL} > 8.7$$ M Z ′ / g BL > 8.7 TeV for $$g_\mathrm{BL}=0.3$$ g BL = 0.3 . We conclude that the NLO+NLL corrections improve the dilepton bounds on the $$Z^{\prime }$$ Z ′ mass and that both dark matter candidates are only viable in the $$Z^{\prime }$$ Z ′ resonance region, with the parameter space for scalar dark matter being fully probed by XENON1T. Lastly, we show that one can successfully have a minimal two-component dark matter model.

Abstract Dirac fermion dark matter models with heavy Z ′ mediators are subject to stringent constraints from spin-independent direct searches and from LHC bounds, cornering them to live near the Z ′ resonance. Such constraints can be relaxed, however, by turning off the vector coupling to Standard Model fermions, thus weakening direct detection bounds, or by resorting to light Z ′ masses, below the Z pole, to escape heavy resonance searches at the LHC. In this work we investigate both cases, as well as the applicability of our findings to Majorana dark matter. We derive collider bounds for light Z ′ gauge bosons using the CL S method, spin-dependent scattering limits, as well as the spin-independent scattering rate arising from the evolution of couplings between the energy scale of the mediator mass and the nuclear energy scale, and indirect detection limits. We show that such scenarios are still rather constrained by data, and that near resonance they could accommodate the gamma-ray GeV excess in the Galactic center.

Within the context of vector mediators, is a new signal observed in flavor changing interactions, particularly in the neutral mesons systems K0−K¯0, D0−D¯0 and B0−B0¯, consistent with dilepton resonance searches at the LHC? In the attempt to address this very simple question, we discuss the complementarity between flavor changing neutral current (FCNC) and dilepton resonance searches at the LHC run 2 at 13 TeV with 3.2 fb−1 of integrated luminosity, in the context of vector mediators at tree level. Vector mediators, are often studied in the flavor changing framework, specially in the light of the recent LHCb anomaly observed at the rare B decay. However, the existence of stringent dilepton bound severely constrains flavor changing interactions, due to restrictive limits on the Z′ mass. We discuss this interplay explicitly in the well motivated framework of a 3-3-1 scheme, where fermions and scalars are arranged in the fundamental representation of the weak SU(3) gauge group. Due to the paucity of relevant parameters, we conclude that dilepton data leave little room for a possible new physics signal stemming from these systems, unless a very peculiar texture parametrization is used in the diagonalization of the CKM matrix. In other words, if a signal is observed in such flavor changing interactions, it unlikely comes from a 3-3-1 model.

Two Higgs Doublet Models (2HDM) are popular extensions of the Standard Model for several reasons, but do not explain neutrino masses. In this work, we investigate how one can incorporate neutrino masses within the framework of the 2HDM-U(1), where U(1) is an abelian gauge symmetry used to nicely address the absence of flavor changing neutral currents in 2HDM. In particular, we explore realizations of the type I and type II seesaw since they are mechanisms that we dote on for being able to generate elegantly small active neutrino masses. We show that one can build several models featuring type I, type II and type I+II seesaw mechanism with different phenomenological implications.

In the light of the new 13 TeV dilepton data set with 3.2 fb−1 integrated luminosity from the ATLAS Collaboration, we derive limits on the Z′ mass in the context of left–right symmetric models and exploit the complementarity with dijet and lljj data, as well as neutrinoless double beta decay. We keep the ratio of the left- and right-handed gauge coupling free in order to take into account different patterns of left–right symmetry breaking. By combining the dielectron and dimuon data we can exclude Z′ masses below 3 TeV for gR=gL, and for gR∼1 we rule out masses up to ∼4 TeV. Those comprise the strongest direct bounds on the Z′ mass from left–right models up to date. We show that in the usual plane of right-handed neutrino and charged gauge boson mass, dilepton data can probe a region of parameter space inaccessible to neutrinoless double beta decay and lljj studies. Lastly, through the mass relation between WR and Z′ we present an indirect bound on the lifetime of neutrinoless double beta decay using dilepton data. Our results prove that the often ignored dilepton data in the context of left–right models actually provide important complementary limits.

General considerations in general relativity and quantum mechanics are known to potentially rule out continuous global symmetries in the context of any consistent theory of quantum gravity. Assuming the validity of such considerations, we derive stringent bounds from gamma-ray, X-ray, cosmic-ray, neutrino, and CMB data on models that invoke global symmetries to stabilize the dark matter particle. We compute up-to-date, robust model-independent limits on the dark matter lifetime for a variety of Planck-scale suppressed dimension-five effective operators. We then specialize our analysis and apply our bounds to specific models including the Two-Higgs-Doublet, Left–Right, Singlet Fermionic, Zee–Babu, 3-3-1 and Radiative See-Saw models. Assuming that (i) global symmetries are broken at the Planck scale, that (ii) the non-renormalizable operators mediating dark matter decay have O(1) couplings, that (iii) the dark matter is a singlet field, and that (iv) the dark matter density distribution is well described by a NFW profile, we are able to rule out fermionic, vector, and scalar dark matter candidates across a broad mass range (keV–TeV), including the WIMP regime.

In canonical left-right symmetric models the lower mass bounds on the charged gauge bosons are in the ballpark of 3–4 TeV, resulting in much stronger limits on the neutral gauge boson ZR, making its production unreachable at the LHC. However, if one evokes different patterns of left-right symmetry breaking the ZR might be lighter than the WR± motivating an independent ZR collider study. In this work, we use the 8 TeV ATLAS 20.3 fb−1 luminosity data to derive robust bounds on the ZR mass using dilepton data. We find strong lower bounds on the ZR mass for different right-handed gauge couplings, excluding ZR masses up to ∼3.2 TeV. For the canonical LR model we place a lower mass bound of ∼2.5 TeV. Our findings are almost independent of the right-handed neutrino masses (∼2% effect) and applicable to general left-right models.