Rm Jet Research Articles

Coronal properties of low-accreting AGNs using Swift, XMM–Newton, and NuSTAR observations

ABSTRACT We studied the broad-band X-ray spectra of Swift/Burst Alert Telescope selected low-accreting active galactic nuclei (AGNs) using the observations from XMM–Newton, Swift, and NuSTAR in the energy range of 0.5–150 keV. Our sample consists of 30 AGNs with Eddington ratio, λEdd < 10−3. We extracted several coronal parameters from the spectral modelling, such as the photon index, hot electron plasma temperature, cutoff energy, and optical depth. We tested whether there exist any correlation/anticorrelation among different spectral parameters. We observe that the relation of hot electron temperature with the cutoff energy in the low accretion domain is similar to what is observed in the high accretion domain. We did not observe any correlation between the Eddington ratio and the photon index. We studied the compactness–temperature diagram and found that the cooling process for extremely low-accreting AGNs is complex. The jet luminosity is calculated from the radio flux, and observed to be related to the bolometric luminosity as $L_{\rm jet} \propto L_{\rm bol}^{0.7}$, which is consistent with the standard radio-X-ray correlation.

Testing leptogenesis at the LHC and future muon colliders: A Z′ scenario

If the masses of at least two generations of right-handed neutrinos (RHNs) are near-degenerate, the scale of leptogenesis can be as low as $\sim$ 100 GeV. In this work, we study probing such resonant leptogenesis in the $B-L$ model at the LHC and future multi-TeV muon colliders via the process $Z'\to NN\to\ell^\pm\ell^\pm+{\rm jets}$, with $Z'$ the $U(1)_{B-L}$ gauge boson and $N$ the RHN. The same-sign dilepton feature of the signal makes it almost background-free, while the event number difference between positive and negative leptons is a hint for $CP$ violation, which is a key ingredient of leptogenesis. We found that resonant leptogenesis can be tested at the HL-LHC for $M_{Z'}$ up to 12 TeV, while at a 10 (30) TeV muon collider the reach can be up to $M_{Z'}\sim28~(100)$ TeV via the off-shell production of $Z'$.

Comparison of the characteristics of magnetars born in death of massive stars and merger of compact objects with swift gamma-ray burst data

ABSTRACT Assuming that the shallow-decaying phase in the early X-ray light curves of gamma-ray bursts (GRBs) is attributed to the dipole radiations (DRs) of a newborn magnetar, we present a comparative analysis for the magnetars born in death of massive stars and merger of compact binaries with long and short GRB (lGRB and sGRB) data observed with the Swift mission. We show that the typical braking index (n) of the magnetars is ∼3 in the sGRB sample, and it is ∼4 for the magnetars in the lGRB sample. Selecting a sub-sample of the magnetars whose spin-down is dominated by DRs (n ≲ 3) and adopting a universal radiation efficiency of 0.3, we find that the typical magnetic field strength (Bp) is 1016 G versus 1015 G and the typical initial period (P0) is ∼20 ms versus 2 ms for the magnetars in the sGRBs versus lGRBs. They follow the same relation between P0 and the isotropic GRB energy as $P_0\propto E_{\rm jet}^{-0.4}$. We also extend our comparison analysis to superluminous supernovae (SLSNe) and stable pulsars. Our results show that a magnetar born in merger of compact stars tends to have a stronger Bp and a longer P0 by about one order of magnitude than that born in collapse of massive stars. Its spin-down is dominated by the magnetic DRs as old pulsars, being due to its strong magnetic field strength, whereas the early spin-down of magnetars born in massive star collapse is governed by both the DRs and gravitational wave (GW) emission. A magnetar with a faster rotation speed should power a more energetic jet, being independent of its formation approach.

A Galactic survey of radio jets from massive protostars

ABSTRACT In conjunction with a previous southern-hemisphere work, we present the largest radio survey of jets from massive protostars to date with high-resolution (∼0.04 arcsec) Jansky Very Large Array observations towards two subsamples of massive star-forming regions of different evolutionary statuses: 48 infrared-bright, massive, young, stellar objects (MYSOs) and 8 infrared dark clouds (IRDCs) containing 16 luminous ($\hbox{$\, L_{\rm {bol}}$}\gt 10^3\hbox{${\rm \, L_{\odot }}$}$) cores. For 94 per cent of the MYSO sample, we detect thermal radio (α ≥ −0.1 whereby Sν ∝ να) sources coincident with the protostar, of which 84 per cent (13 jets and 25 candidates) are jet like. Radio luminosity is found to scale with $\hbox{$\, L_{\rm {bol}}$}$ similarly to the low-mass case supporting a common mechanism for jet production across all masses. Associated radio lobes tracing shocks are seen towards 52 per cent of jet-like objects and are preferentially detected towards jets of higher radio and bolometric luminosities, resulting from our sensitivity limitations. We find jet mass-loss rate scales with bolometric luminosity as $\hbox{$\dot{m}_{\rm jet}$}\propto \hbox{$\, L_{\rm {bol}}$}^{0.9\pm 0.2}$, thereby discarding radiative, line-driving mechanisms as the dominant jet-launching process. Calculated momenta show that the majority of jets are mechanically capable of driving the massive, molecular outflow phenomena since pjet > poutflow. Finally, from their physical extent we show that the radio emission cannot originate from small, optically thick H ii regions. Towards the IRDC cores, we observe increasing incidence rates/radio fluxes with age using the proxy of increasing luminosity-to-mass (L/M) and decreasing infrared flux ratios $({S_{70{\rm \, \mu m}}}/{S_{24{\rm \, \mu m}}})$. Cores with $({L}/{M})\,\lt \,40\, \hbox{${\rm \, L_{\odot }}$}\hbox{${\rm \, M_{\odot }}$}^{-1}$ are not detected above ($5.8{\rm \, GHz}$) radio luminosities of ${\sim}1{\rm \, mJy}{\rm \, kpc}^2$.

Possible evidence of a universal radio/X-ray correlation in a near-complete sample of hard X-ray selected seyfert galaxies

ABSTRACT Because the disc–jet coupling likely depends on various properties of sources probed, the sample control is always an important but challenging task. In this work, we re-analysed the INTEGRAL hard X-ray-selected sample of Seyfert galaxies. We only consider sources that have measurements in black hole (BH) mass, and luminosities in radio and X-rays. Our final sample includes 64 (out of the original 79) sources, consists of both bright active galactic nucleus and low-luminosity ones. The 2–10 keV X-ray Eddington ratio LX/LEdd locates in the range between ∼10−4.5 and ∼10−0.5. We first find that, because of the similarity in the LHX/LX distribution, the X-ray origin of radio-loud Seyferts may be the same to that of radio-quiet (RQ) ones, where we attribute to the hot accretion flow (or similarly, the corona). We then investigate the connections between luminosities in radio and X-rays. Since our sample suffers a selection bias of a BH mass MBH dependence on LX/LEdd, we focus on the correlation slope ξX between the radio (at 1.4 GHz) and X-ray luminosities in Eddington unit, i.e. $({L_{\rm R}}/{L_{\rm Edd}}) \propto ({L_{\rm X}}/{L_{\rm Edd}})^{\xi _{\rm X}}$. We classify the sources according to various properties, i.e. 1) Seyfert classification, 2) radio loudness, and 3) radio morphology. We find that, despite these differences in classification, all the sources in our sample are consistent with a universal correlation slope ξX (note that the normalization may be different), with ξX = 0.77 ± 0.10. This is unexpected, considering various possible radio emitters in RQ systems. For the jet (either relativistic and well collimated, or sub-relativistic and weakly collimated) interpretation, our result may suggest a common/universal but to be identified jet launching mechanism among all the Seyfert galaxies, while properties like BH spin and magnetic field strength only play secondary roles. We further estimate the jet production efficiency ηjet of Seyfert galaxies, which is $\eta _{\rm jet}\approx 1.9^{+0.9}_{-1.5}\times 10^{-4}$ on average. We also find that ηjet increases as the system goes fainter. Alternative scenarios for the radio emission in RQ systems are also discussed.

Saturation and forward jets in proton-lead collisions at the LHC

We investigate the forward-jet energy spectrum within the Color Glass Condensate framework at 5 TeV center-of-mass energy. In particular, we focus on the kinematic range covered by the CMS-CASTOR calorimeter. We show that our saturation-model calculations are compatible with the CASTOR measurements and that to optimally reproduce the data, effects of multi-parton interactions need to be included. We predict a significant nuclear suppression - reaching down to 50% at the lowest considered jet energies $E_{\rm jet} \sim 500 \, {\rm GeV}$.

The delay time of gravitational wave — gamma-ray burst associations

The first gravitational wave (GW) - gamma-ray burst (GRB) association, GW170817/GRB 170817A, had an offset in time, with the GRB trigger time delayed by $\sim$1.7 s with respect to the merger time of the GW signal. We generally discuss the astrophysical origin of the delay time, $\Delta t$, of GW-GRB associations within the context of compact binary coalescence (CBC) -- short GRB (sGRB) associations and GW burst -- long GRB (lGRB) associations. In general, the delay time should include three terms, the time to launch a clean (relativistic) jet, $\Delta t_{\rm jet}$; the time for the jet to break out from the surrounding medium, $\Delta t_{\rm bo}$; and the time for the jet to reach the energy dissipation and GRB emission site, $\Delta t_{\rm GRB}$. For CBC-sGRB associations, $\Delta t_{\rm jet}$ and $\Delta t_{\rm bo}$ are correlated, and the final delay can be from 10 ms to a few seconds. For GWB-lGRB associations, $\Delta t_{\rm jet}$ and $\Delta t_{\rm bo}$ are independent. The latter is at least $\sim$10 s, so that $\Delta t$ of these associations is at least this long. For certain jet launching mechanisms of lGRBs, $\Delta t$ can be minutes or even hours long due to the extended engine waiting time $\Delta t_{\rm wait}$ to launch a jet. We discuss the cases of GW170817/GRB 170817A and GW150914/GW150914-GBM within this theoretical framework and suggest that the delay times of future GW/GRB associations will shed light into the jet launching mechanisms of GRBs.

Magnetar as Central Engine of Gamma-Ray Bursts: Central Engine–Jet Connection, Wind–Jet Energy Partition, and Origin of Some Ultra-long Bursts

Gamma-ray burst (GRB) central engines and jet production mechanisms are still open questions. Assuming that the shallow decay segments of canonical X-ray afterglow lightcurves of {\em Swift} GRBs are attributed to the magnetic dipole (MD) radiations of newly-born magnetars, we derive the parameters of the magnetars and explore their possible relations to jet and MD wind emission. We show that the magnetar initial spin period ($P_0$) are tightly correlated with the jet energy ($E_{\rm jet}$), which is almost proportional to the wind energy ($E_{\rm wind}$). Our least square fits yield $P_0\propto E^{-0.36\pm 0.03}_{\rm jet}$ and $E_{\rm wind}\propto E^{0.91\pm 0.07}_{\rm jet}$. These relations may imply that a magnetar with faster rotating speed can power a more energetic GRB, and energy partition between the jet and wind may be quasi-universal. Although the $P_0-E_{\rm jet}$ relation is driven by a few sub-energetic GRBs in our sample, our Monte Carlo simulation analysis shows that sample selection biases from instrumental flux limits and contaminations of the bright jet afterglows cannot make this correlation. Within this jet-wind paradigm, we propose that GRB 101225A-like ultra-long GRBs, whose prompt gamma-ray/X-ray lightcurves are featured as a long-lasting plateau with a sharp drop, may be the orphan MD wind emission being due to misalignment of their jet axis to the light of sight. Brief discussion on the orphan MD wind emission and its association with the gravitational wave radiation of newly-born magnetars is presented.

A model for the radio/X-ray correlation in three neutron star low-mass X-ray binaries 4U 1728-34, Aql X-1ad, and EXO 1745-248

Observationally, for neutron star low-mass X-ray binaries, so far, the correlation between the radio luminosity $L_{\rm R}$ and the X-ray luminosity $L_{\rm X}$, i.e., $L_{\rm R}\propto L_{\rm X}^{\beta}$, has been reasonably well-established only in three sources 4U 1728-34, Aql X-1 and EXO 1745-248 in their hard state. The slope $\beta$ of the radio/X-ray correlation of the three sources is different, i.e., $\beta \sim 1.4$ for 4U 1728-34, $\beta \sim 0.4$ for Aql X-1, and $\beta \sim 1.6$ for EXO 1745-248. In this paper, for the first time we explain the different radio/X-ray correlation of 4U 1728-34, Aql X-1 and EXO 1745-248 with the coupled advection-dominated accretion (ADAF)-jet model respectively. We calculate the emergent spectrum of the ADAF-jet model for $L_{\rm X}$ and $L_{\rm R}$ at different $\dot m$ ($\dot m=\dot M/\dot M_{\rm Edd}$), adjusting $\eta$ ($\eta \equiv \dot M_{\rm jet}/\dot M$, describing the fraction of the accreted matter in the ADAF transfered vertically forming the jet) to fit the observed radio/X-ray correlations. Then we derive a fitting formula of $\eta$ as a function of $\dot m$ for 4U 1728-34, Aql X-1 and EXO 1745-248 respectively. If the relation between $\eta$ and $\dot m$ can be extrapolated down to a lower value of $\dot m$, we find that in a wide range of $\dot m$, the value of $\eta$ in Aql X-1 is greater than that of in 4U 1728-34 and EXO 1745-248, implying that Aql X-1 may have a relatively stronger large-scale magnetic field, which is supported by the discovery of the coherent millisecond X-ray pulsation in Aql X-1.

MHD simulations of the formation and propagation of protostellar jets to observational length-scales

We present 2.5-D global, ideal MHD simulations of magnetically and rotationally driven protostellar jets from Keplerian accretion discs, wherein only the initial magnetic field strength at the inner radius of the disc, $B_{\rm i}$, is varied. Using the AMR-MHD code AZEUS, we self-consistently follow the jet evolution into the observational regime ($>10^3\,\mathrm{AU}$) with a spatial dynamic range of $\sim6.5\times10^5$. The simulations reveal a three-component outflow: 1) A hot, dense, super-fast and highly magnetised 'jet core'; 2) a cold, rarefied, trans-fast and highly magnetised 'sheath' surrounding the jet core and extending to a tangential discontinuity; and 3) a warm, dense, trans-slow and weakly magnetised shocked ambient medium entrained by the advancing bow shock. The simulations reveal power-law relationships between $B_{\rm i}$ and the jet advance speed, $v_{\rm jet}$, the average jet rotation speed, $\langle v_\varphi\rangle$, as well as fluxes of mass, momentum, and kinetic energy. Quantities that do not depend on $B_{\rm i}$ include the plasma-$\beta$ of the transported material which, in all cases, seems to asymptote to order unity. Jets are launched by a combination of the 'magnetic tower' and 'bead-on-a-wire' mechanisms, with the former accounting for most of the jet acceleration---even for strong fields---and continuing well beyond the fast magnetosonic point. At no time does the leading bow shock leave the domain and, as such, these simulations generate large-scale jets that reproduce many of the observed properties of protostellar jets including their characteristic speeds and transported fluxes.

A newly discovered double–double candidate microquasar in NGC 300

We present the discovery of a powerful candidate microquasar in NGC 300, associated with the S 10 optical nebula (previously classified as a supernova remnant). Chandra images show four discrete X-ray knots aligned in the plane of the sky over a length of $\approx$150 pc. The X-ray emission from the knots is well fitted with a thermal plasma model at a temperature of $\approx$0.6 keV and a combined 0.3-8 keV luminosity of $\approx$10$^{37}$ erg s$^{-1}$. The X-ray core, if present at all, does not stand out above the thermal emission of the knots: this suggests that the accreting compact object is either currently in a dim state or occulted from our view. We interpret the emission from the knots as the result of shocks from the interaction of a jet with the interstellar medium (possibly over different epochs of enhanced activity). Cooler shock-heated gas is likely the origin also of the optical bubble and lobes near the X-ray structure, detected in images from the Hubble Space Telescope and the Very Large Telescope. In the radio bands, we observed the region with the Australia Telescope Compact Array, and discovered an elongated radio nebula (about 170 $\times$ 55 pc in size) with its major axis aligned with the chain of Chandra sources. The radio nebula has an integrated 5.5 GHz radio luminosity of $\approx$10$^{34}$ erg s$^{-1}$ for a distance of 1.88 Mpc. The morphology, size and luminosity of the extended X-ray, optical and radio structure suggest that NGC 300-S 10 belongs to the same class of powerful ($P_{\rm jet} > 10^{39}$ erg s$^{-1}$) microquasars as SS 433, Ho II X-1 and NGC 7793-S 26.

H5±±h0 production via vector-boson fusion in the Georgi-Machacek model at hadron colliders

The Georgi-Machacek (GM) model is a distinctive TeV-scale extension of the Standard Model (SM) due to the introduction of two (one real and one complex) scalar triplets to the Higgs sector. It predicts the existence of doubly charged Higgs bosons $H_5^{\pm\pm}$ and the vacuum expectation value of Higgs triplets $v_\Delta$ can reach a few tens of GeV. In this paper, we perform a parameter scan of the GM model within the H5plane benchmark scenario and investigate in detail the single production of a doubly charged Higgs boson in association with a SM-like Higgs boson via vector-boson fusion at the $14~ {\rm TeV}$ LHC and $70~ {\rm TeV}$ Super Proton-Proton Collider. Both integrated cross section and differential distributions with respect to some kinematic variables for $pp \rightarrow W^{\pm}W^{\pm} \rightarrow H_5^{\pm\pm} h^0 + 2\, {\rm jets}$ are provided up to the QCD next-to-leading order. In the signal-background analysis we employ the {\sc madspin} method to take into account the spin correlation and finite width effects of the intermediate Higgs and $W$ bosons and present some kinematic distributions of final leptons. The numerical results show that the SM background can be suppressed remarkably and the $H_5^{\pm\pm} h^0$ vector-boson fusion signal can be directly detected at future high-luminosity, high-energy hadron colliders by imposing a proper cut on the transverse mass $M_{T, \ell_1 \ell_2}$.

Accretion flow dynamics during 1999 outburst of XTE J1859+226—modeling of broadband spectra and constraining the source mass

We examine the dynamical behavior of accretion flow around XTE J1859+226 during the 1999 outburst by analyzing the entire outburst data ($\sim$ 166 days) from RXTE Satellite. Towards this, we study the hysteresis behavior in the hardness intensity diagram (HID) based on the broadband ($3 - 150$ keV) spectral modeling, spectral signature of jet ejection and the evolution of Quasi-periodic Oscillation (QPO) frequencies using the two-component advective flow model around a black hole. We compute the flow parameters, namely Keplerian accretion rate (${\dot m}_d$), sub-Keplerian accretion rate (${\dot m}_h$), shock location ($r_s$) and black hole mass ($M_{bh}$) from the spectral modeling and study their evolution along the q-diagram. Subsequently, the kinetic jet power is computed as $L^{\rm obs}_{\rm jet}\sim 3 - 6 \times 10^{37}$ erg~s$^{-1}$ during one of the observed radio flares which indicates that jet power corresponds to $8-16\%$ mass outflow rate from the disc. This estimate of mass outflow rate is in close agreement with the change in total accretion rate ($\sim 14\%$) required for spectral modeling before and during the flare. Finally, we provide a mass estimate of the source XTE J1859+226 based on the spectral modeling that lies in the range of $5.2 - 7.9 M_{\odot}$ with 90\% confidence.

The nuclear activity and central structure of the elliptical galaxy NGC 5322

We have analysed a new high-resolution e-MERLIN 1.5 GHz radio continuum map together with $HST$ and SDSS imaging of NGC 5322, an elliptical galaxy hosting radio jets, aiming to understand the galaxy's central structure and its connection to the nuclear activity. We decomposed the composite $HST$ + SDSS surface brightness profile of the galaxy into an inner stellar disc, a spheroid, and an outer stellar halo. Past works showed that this embedded disc counter-rotates rapidly with respect to the spheroid. The $HST$ images reveal an edge-on nuclear dust disc across the centre, aligned along the major-axis of the galaxy and nearly perpendicular to the radio jets. After careful masking of this dust disc, we find a central stellar mass deficit $M_{\rm def}$ in the spheroid, scoured by SMBH binaries with final mass $M_{\rm BH}$ such that $M_{\rm def}/M_{\rm BH} \sim 1.3 - 3.4$. We propose a three-phase formation scenario for NGC 5322 where a few ($2-7$) "dry" major mergers involving SMBHs built the spheroid with a depleted core. The cannibalism of a gas-rich satellite subsequently creates the faint counter-rotating disc and funnels gaseous material directly onto the AGN, powering the radio core with a brightness temperature of $T_{\rm B,core} \sim 4.5 \times 10^{7}$ K and the low-power radio jets ($P_{\rm jets}\sim 7.04 \times 10^{20}$ W Hz$^{-1}$) which extend $\sim 1.6$ kpc. The outer halo can later grow via minor mergers and the accretion of tidal debris. The low-luminosity AGN/jet-driven feedback may have quenched the late-time nuclear star formation promptly, which could otherwise have replenished the depleted core.

The effects of protostellar jet feedback on turbulent collapse

We present results of hydrodynamic simulations of massive star forming regions with and without protostellar jets. We show that jets change the normalization of the stellar mass accretion rate, but do not strongly affect the dynamics of star formation. In particular, $M_*(t) \propto f^2 (t-t_*)^2$ where $f = 1 - f_{\rm jet}$ is the fraction of mass accreted onto the protostar, $f_{\rm jet}$ is the fraction ejected by the jet, and $(t-t_*)^2$ is the time elapsed since the formation of the first star. The star formation efficiency is nonlinear in time. We find that jets have only a small effect (of order 25\%) on the accretion rate onto the protostellar disk (the "raw" accretion rate). We show that the small scale structure -- the radial density, velocity, and mass accretion profiles are very similar in the jet and no-jet cases. Finally, we show that the inclusion of jets does drive turbulence but only on small (parsec) scales.

Study of J/ψ Production in Jets.

The production of J/ψ mesons in jets is studied in the forward region of proton-proton collisions using data collected with the LHCb detector at a center-of-mass energy of 13TeV. The fraction of the jet transverse momentum carried by the J/ψ meson, z(J/ψ)≡p_{T}(J/ψ)/p_{T}(jet), is measured using jets with p_{T}(jet)>20 GeV in the pseudorapidity range 2.5<η(jet)<4.0. The observed z(J/ψ) distribution for J/ψ mesons produced in b-hadron decays is consistent with expectations. However, the results for prompt J/ψ production do not agree with predictions based on fixed-order nonrelativistic QCD. This is the first measurement of the p_{T} fraction carried by prompt J/ψ mesons in jets at any experiment.

Transverse single-spin asymmetries in ℓp↑→hX within a TMD approach: Role of quasireal photon exchange

We present an updated study of transverse single-spin asymmetries for the inclusive large-$P_T$ processes $\ell \, p^\uparrow \to h\, X$ and $\ell\, p^\uparrow \to {\rm jet}\,X$, within a transverse momentum-dependent approach, including the contribution of quasireal (Weizs\"acker-Williams) photons. In the spirit of a unified transverse momentum-dependent scheme, predictions are obtained adopting the Sivers and transversity distributions and the Collins fragmentation functions as extracted from fits to the azimuthal asymmetries measured in semi-inclusive deep inelastic scattering and $e^+e^-$ annihilation processes. The description of the available data is extremely good, showing a clear general improvement with respect to the previous leading-order analysis. Predictions for unpolarized cross sections and single-spin asymmetries for ongoing and future experiments are also given.

Measurement of the tt¯ production cross section in the τ+jets final state in pp collisions at s=8 TeV using the ATLAS detector

A measurement of the inclusive $pp\to t\bar{t}+X$ production cross section in the $\tau+{\rm jets}$ final state using only the hadronic decays of the $\tau$ lepton is presented. The measurement is performed using 20.2 fb$^{-1}$ of proton-proton collision data recorded at a center-of-mass energy of $\sqrt{s}=8$ TeV with the ATLAS detector at the Large Hadron Collider. The cross section is measured via a counting experiment by imposing a set of selection criteria on the identification and kinematic variables of the reconstructed particles and jets, and on event kinematic variables and characteristics. The production cross section is measured to be $\sigma_{t\bar{t}}= 239 \pm 29$ pb, which is in agreement with the measurements in other final states and the theoretical predictions at this center-of-mass energy.

Phenomenology of an SU(2)1×SU(2)2×U(1)Y model at the LHC

We investigate the implications of a minimal $SU(2)$ gauge symmetry extension of the standard model at the LHC. To achieve the spontaneous symmetry breaking, a heavy Higgs doublet of the $SU(2)$ is introduced. To obtain an anomaly free model and the decays of new charged gauge bosons, we include a vector-like quark doublet. We also employ a real scalar boson to dictate the heavy Higgs production via the gluon-gluon fusion processes. It is found that the new gauge coupling and the masses of new gauge bosons can be strictly bounded by the electroweak $\rho$-parameter and dilepton resonance experiments at the LHC. It is found that due to the new charged gauge boson enhancement, the cross sections for a heavy scalar boson to diphoton channel measured by ATLAS and CMS can be easily satisfied when the values of Yukawa couplings are properly taken. Furthermore, by adopting event simulation, we find that the significance of $pp\to (\gamma \gamma)_H+{\rm jet}$, where the diphoton is from the heavy Higgs decay, can be over $4\sigma$ when the luminosity is above 60 fb$^{-1}$.

QCD and electroweak corrections toZZ+jetproduction withZ-boson leptonic decays at the LHC

In this paper we present the full NLO QCD + NLO EW corrections to the $Z$-boson pair production in association with a hard jet at the LHC. The subsequent $Z$-boson leptonic decays are included by adopting both the naive NWA and MadSpin methods for comparison. Since the $ZZ+{\rm jet}$ production is an important background for single Higgs boson production and new physics search at hadron colliders, the theoretical predictions with high accuracy for the hadronic production of $ZZ+{\rm jet}$ are necessary. We present the numerical results of the integrated cross section and various kinematic distributions of final particles, and conclude that it is necessary to take into account the spin correlation and finite width effects from the $Z$-boson leptonic decays. We also find that the NLO EW correction is quantitatively nonnegligible in matching the experimental accuracy at the LHC, particularly is significant in high transverse momentum region.