Jet Production Research Articles

The stringent upper limit on jet power in the persistent soft-state source 4U 1957+11

ABSTRACT We present extremely deep upper limits on the radio emission from 4U 1957+11, an X-ray binary that is generally believed to be a persistently accreting black hole that is almost always in the soft state. We discuss a more comprehensive search for Type I bursts than in past work, revealing a stringent upper limit on the burst rate, bolstering the case for a black hole accretor. The lack of detection of this source at the 1.07 μJy/beam noise level indicates jet suppression that is stronger than expected even in the most extreme thin disc models for radio jet production – the radio power here is 1500–3700 times lower than the extrapolation of the hard state radio/X-ray correlation, with the uncertainties depending primarily on the poorly constrained source distance. We also discuss the location and velocity of the source and show that it must have either formed in the halo or with a strong asymmetric natal kick.

Heavy-flavour correlations and jets with ALICE at the LHC

This contribution summarises the results on heavy-flavour correlations and jets measured with ALICE detector. Studies of D0-tagged jets are presented in various collision systems and energies. The measurement of the fraction of jet momentum carried by the D0 meson in the direction of the jet axis in pp collisions at and 13 TeV as well as the nuclear modification factor in p–Pb and Pb–Pb collisions are presented. The measurements of the production of jets tagged by electrons from heavy-flavour decays in pp and p–Pb are compared to expectations from POWHEG+PYTHIA8 simulations. The p T-differential cross section of b-tagged jets in p–Pb collisions is also reported and compared to expectations from POWHEG event generator. The azimuthal correlation of D mesons with charged particles in pp and p–Pb collisions are also presented.

Research on Evolution Process and Control Method of External Shapes in the Life-cycle of Modern Civil Jets

External shape is a key property of aircraft. With the wide application of digital technology, various external shapes are produced in different states and different uses in the life-cycle of modern civil jets. If these external shapes are not clearly distinguished, they might be used improperly. Therefore, in this paper, various shapes in the full life-cycle of modern civil jets are defined, and the evolution process of these external shapes is researched. Based on the control of these external shapes, some advanced management methods are put forward, which have been successfully applied in civil jet development in China, and effectively improve the efficiency of civil jet product development.

Cold Atmospheric Pressure Plasma Jet for the Improvement of Wettability of Polypropylene

This paper reports the generation of cold plasma jet working under atmospheric pressure condition, for surface treatment of polymeric films. The discharge has been characterized by electrical and optical methods. The electrical property of the discharge has been studied by taking current-voltage wave forms using voltage and current probes. The production of argon plasma jet is done in atmospheric conditions which are relatively much cheaper, convenient, and safer to use. The atmospheric pressure plasma jet sustained in pure argon has been used to improve wettability of polypropylene (PP). Cold atmospheric pressure plasma jet (CAPPJ) has been generated by a high-voltage power supply (5.5 kV, 0-20 kV) at an operating frequency of 20 kHz. The surface properties of the controls and plasma-treated PP samples were characterized by contact angle measurement, surface free energy measurement, scanning electron microscopy, and the Fourier transform-infrared spectroscopy analysis.

The complete set of two-loop master integrals for Higgs + jet production in QCD

In this paper we complete the computation of the two-loop master integrals relevant for Higgs plus one jet production initiated in [1–3]. Specifically, we compute the remaining family of non-planar master integrals. The computation is performed by defining differential equations along contours in the kinematic space, and by solving them in terms of one-dimensional generalized power series. This method allows for the efficient evaluation of the integrals in all kinematic regions, with high numerical precision. We show the generality of our approach by considering both the top- and the bottom-quark contributions. This work along with [1–3] provides the full set of master integrals relevant for the NLO corrections to Higgs plus one jet production, and for the real-virtual contributions to the NNLO corrections to inclusive Higgs production in QCD in the full theory.

Parity-violating semi-inclusive deeply inelastic scattering at the Electron-Ion Collider

We present a systematic calculation of the current jet production semi-inclusive deeply inelastic scattering process at the Electron-Ion Collider energy. Contributions from weak interactions are considered which give rise to parity violating effects. We consider the general form of the polarized electron beam scattering off the polarized target which has spin 1. The calculations are carried out up to twist-3 level in the quantum chromodynamics parton model by applying the collinear expansion where multiple gluon scattering is taken into account and gauge links are obtained automatically. We present complete results for structure functions and spin/azimuthal asymmetries in terms of the gauge invariant transverse momentum dependent parton distribution functions. Both the unpolarized and the polarized electron beam cases correspond to 24 azimuthal asymmetries, in which 6 of them appear at the leading twist, while 18 of them contribute at twist-3 level. In addition we also calculate the parity-violating asymmetries which arise from the interference of the electromagnetic and weak interactions.

Low temperature transformation of lignocellulose derived bioinspired molecules to aviation fuel precursor over magnesium–lanthanum mixed oxide catalyst

Basic magnesium–lanthanum (Mg–La) mixed oxide materials with tunable interaction between Mg and La oxides were prepared for the low temperature production of green diesel and jet fuel intermediates via aldol condensation reaction. The prepared materials were thoroughly analysedby microscopic and spectroscopic techniques to elucidate its structural properties, including the determination of surface area and basic strengths. Among the tested materials, ML-3 catalyst reflects superior activity for CC bond formation between 5-hydroxymethylfurfural (HMF) and acetone, exhibiting >99% HMF conversion and 89% yield of the precursory C9 4-[5-(Hydroxymethyl)-2-furanyl]-3-butene-2-one product (HAc). Higher conversion and better product selectivity of ML-3 catalyst ascribe to the higher basic strength, moderate surface area and strong interaction between both the metals (Mg and La) in their mixed oxide forms. To understand the role of active sites, zeroth, first and second order kinetics were plotted, and a possible mechanism of CC bond formation was hypothesized. In order to rationalize the role of active ML-3 catalyst, HMF (and furfural) chain lengths were extended with different carbonyl compounds leading the formation of branched and cyclic chain (C9–C15) hydrocarbon precursors.

Jet efficiencies and black hole spins in jetted quasars

ABSTRACT The mechanisms responsible for the production of relativistic jets from supermassive black holes (SMBHs) accreting at near-Eddington rates are not well understood. Simple theoretical expectations indicate that SMBHs in quasars accrete via thin discs which should produce at most very weak jets. This is contradicted by observations of powerful jets in flat-spectrum radio quasars (FSRQs). We use gamma-ray luminosities observed with the Fermi Large Area Telescope as a proxy of the jet power for a population of 154 FSRQs. Assuming typical quasar accretion rates and using black hole (BH) mass measurements from a variety of methods, we find a mean jet production efficiency of about 10 per cent for FSRQs, with values as high as 222 per cent. We find that this is consistent with FSRQs hosting moderately thin, magnetically arrested accretion discs around rapidly spinning BHs. Modelling our observations using general relativistic magnetohydrodynamic (GRMHD) simulations of jets from thin discs, we find an average lower limit of a* = 0.59 for the SMBH spins of FSRQs, with tendency for the spins to decrease as the BH mass increases. Our results are consistent with the merger-driven evolution of SMBHs. 3 per cent of the sample cannot be explained by current GRMHD models of jet production from Kerr BHs due to the high efficiencies. Along the way, we find a correlation between BH masses and Lγ which may be an useful mass estimator in blazar gamma-ray studies.

Two-loop QCD-EW master integrals for Z plus jet production at large transverse momentum

The production of electroweak Z bosons that decay to neutrinos and recoil against jets with large transverse momentum p⊥ is an important background process to searches for dark matter at the Large Hadron Collider (LHC). To fully benefit from opportunities offered by the future high-luminosity LHC, the theoretical description of the pp → Z + j process should be extended to include mixed QCD-electroweak corrections. The goal of this paper is to initiate the computation of such corrections starting with the calculation of the Feynman integrals needed to describe two-loop QCD-electroweak contributions to qoverline{q} → Z + g scattering amplitudes. Making use of the hierarchy between the large transverse momenta of the recoiling jet, relevant for heavy dark matter searches, and the Z boson mass mZ , we present the relevant master integrals as a series expansion in mZ/p⊥.

Onset of Magnetic Explosion in Solar Coronal Jets in Quiet Regions on the Central Disk

Abstract We examine the initiation of 10 coronal jet eruptions in quiet regions on the central disk, thereby avoiding near-limb spicule-forest obscuration of the slow-rise onset of the minifilament eruption. From the Solar Dynamics Observatory/Atmospheric Imaging Assembly 171 Å 12 s cadence movie of each eruption, we (1) find and compare the start times of the minifilament's slow rise, the jet-base bright point, the jet-base-interior brightening, and the jet spire, and (2) measure the minifilament's speed at the start and end of its slow rise. From (a) these data, (b) prior observations showing that each eruption was triggered by magnetic flux cancelation under the minifilament, and (c) the breakout-reconnection current sheet observed in one eruption, we confirm that quiet-region jet-making minifilament eruptions are miniature versions of CME-making filament eruptions, and surmise that in most quiet-region jets: (1) the eruption starts before runaway reconnection starts, (2) runaway reconnection does not start until the slow-rise speed is at least ∼1 km s−1, and (3) at and before eruption onset, there is no current sheet of appreciable extent. We therefore expect that (i) many CME-making filament eruptions are triggered by flux cancelation under the filament, (ii) emerging bipoles seldom, if ever, directly drive jet production because the emergence is seldom, if ever, fast enough, and (iii) at a separatrix or quasi-separatrix in any astrophysical setting of a magnetic field in low-beta plasma, a current sheet of appreciable extent can be built only dynamically by a magnetohydrodynamic convulsion of the field, not by quasi-static gradual converging of the field.

Jet charge modification in finite QCD matter

Jet production and jet substructure modification in heavy-ion collisions have played an essential role in revealing the in-medium evolution of parton showers and the determination of the properties of strongly-interacting matter under extreme conditions. It is imperative to extend these studies to include flavor tagging and to devise observables that are sensitive to the partonic origin of jets. The average jet charge, defined as the momentum-weighted sum of the electric charges of particles inside the jet, is a proxy of the electric charge of the quark or gluon that initiates the jet. We demonstrate how the factorization framework of soft-collinear effective theory can be generalized to evaluate the jet charge in a dense strongly-interacting matter environment, such as the one produced in nuclear reactions at collider energies. Observables that can separate the contribution of in-medium branching from the trivial isospin effects are identified and their connection to established jet quenching effects is elucidated. We present predictions for the transverse momentum dependence of the jet charge distribution in nucleus-nucleus collisions and its modification relative to the proton case.

On the Jet Production Efficiency in a Sample of the Youngest Radio Galaxies

Abstract Here we discuss the jet production efficiency in a sample of 17 young radio galaxies with measured redshifts, kinematic ages, and nuclear X-ray fluxes, for which the observed luminosities of compact jets/lobes and accretion disks correspond to the same episode of AGN activity. For the targets, we analyze the available optical data, estimating the bolometric luminosities of the accretion disks L bol, and the black hole masses; we also derive the minimum jet kinetic luminosities, P j. With this information we investigate the distribution of our sample in the three-dimensional space of the accretion rate λ Edd ≡ L bol/L Edd, the nuclear X-ray luminosity L X considered here as a limit for the emission of the disk coronae, and P j, expressing the latter two parameters either in the Eddington units, or in the units of the disk luminosity. We find that (i) the accretion rate λ Edd in our sample is distributed within a narrow range λ Edd ∼ 0.01–0.2; (ii) the normalized jet power P j/L Edd formally correlates with the accretion rate λ Edd, with some saturation at the largest values λ Edd > 0.05; (iii) the jet production efficiency spans a range from η jet ≲ 10−3 up to ∼0.2 at maximum, which is below the level expected for magnetically arrested disks around maximally spinning black holes; and (iv) there is a diversification in η jet on the hardness–intensity diagram L X/L bol − λ Edd, with the jets being produced most efficiently during the high/hard states, and suppressed during the soft states.

Isolated photon and photon+jet production at NNLO QCD accuracy

We describe the calculation of the next-to-next-to-leading order (NNLO) QCD corrections to isolated photon and photon-plus-jet production, and discuss how the experimental hadron-level photon definition and isolation criteria can be approximated in the theoretical parton-level calculation. The NNLO corrections lead to a considerable reduction of the theory uncertainty on the predictions, typically to less than five per cent, and enable an improved description of experimental measurements from ATLAS and CMS.

Host Galaxies of Type Ic and Broad-lined Type Ic Supernovae from the Palomar Transient Factory: Implications for Jet Production

Abstract Unlike ordinary supernovae (SNe), some of which are hydrogen and helium deficient (called Type Ic SNe), broad-lined Type Ic SNe (SNe Ic-bl) are very energetic events, and only SNe Ic-bl are coincident with long-duration gamma-ray bursts (GRBs). Understanding the progenitors of SN Ic-bl explosions versus those of their SN Ic cousins is key to understanding the SN–GRB relationship and jet production in massive stars. Here we present the largest existing set of host galaxy spectra of 28 SNe Ic and 14 SNe Ic-bl, all discovered by the same galaxy-untargeted survey, namely, the Palomar Transient Factory (PTF). We carefully measure their gas-phase metallicities, stellar masses (M *), and star formation rates (SFRs). We further reanalyze the hosts of 10 literature SN–GRBs using the same methods and compare them to our PTF SN hosts with the goal of constraining their progenitors from their local environments. We find that the metallicities, SFRs, and M * values of our PTF SN Ic-bl hosts are statistically comparable to those of SN–GRBs but significantly lower than those of the PTF SNe Ic. The mass–metallicity relations as defined by the SNe Ic-bl and SN–GRBs are not significantly different from the same relations as defined by Sloan Digital Sky Survey galaxies, contradicting claims by earlier works. Our findings point toward low metallicity as a crucial ingredient for SN Ic-bl and SN–GRB production since we are able to break the degeneracy between high SFR and low metallicity. We suggest that the PTF SNe Ic-bl may have produced jets that were choked inside the star or were able to break out of the star as unseen low-luminosity or off-axis GRBs.

The leading jet transverse momentum in inclusive jet production and with a loose jet veto

We study the transverse momentum of the leading jet in the limit where the jet radius is small, R ≪ 1. We introduce the leading-jet function to calculate this cross section for an inclusive jet sample, and the subleading-jet function when a loose veto on additional jets is imposed, i.e. {}_{PTJ}{underset{sim }{>}}_{P_T^{mathrm{veto}}} . These jet functions are calculated at next-to-leading order in QCD and the resummation of jet radius logarithms is explored. We present phenomenological results for Higgs + 1 jet production, for both the jet and Higgs transverse momentum distribution. We find that, while the R ≪ 1 limit of the cross section provides a good description of the full NLO result, even for values as large as R = 0.8, simply retaining the leading logarithm at this order does not. Indeed, the NLO contribution to the hard function and, to a lesser extent, non-logarithmic corrections to the jet function are sizable and must be included to obtain the correct cross section. In the inclusive cross section we find that the {alpha}_s^2 ln2R corrections are several precent, while in exclusive cross sections at large pT ,J and small R they can reach 20%. However, it is not clear how important the resummation of these logarithms is, given the presence of other large corrections at NNLO.

High-energy cosmic ray production in X-ray binary jets

ABSTRACT As smaller analogues of active galactic nuclei, X-ray binaries (XRBs) are also capable of launching jets that accelerate particles to high energies. In this work, we re-examine XRB jets as potential sources of high-energy cosmic rays (CRs) and explore whether they could provide a significant second Galactic component to the CR spectrum. In the most intriguing scenario, XRB-CRs could dominate the observed spectrum above the so-called knee feature at ∼3 × 1015 eV, offering an explanation for several key issues in this transition zone from Galactic to extragalactic CRs. We discuss how such a scenario could be probed in the near future via multimessenger observations of XRB jets, as well as diffuse Galactic neutrino flux measurements.

Forward physics results on jet production and energy flow at the LHC

In this paper, we present a review of forward physics measurements performed with LHC Runs 1 and 2 data. In particular, measurements based on proton–proton collisions with different center-of-mass energies (0.9–13 TeV) are reviewed. We focus on measurements exploring the forward phase space using the available instrumentation at the different LHC experiments, and report on forward jet and forward energy flow measurements.

Internal reduction method for computing Feynman integrals

A new approach to compute Feynman Integrals is presented. It relies on an integral representation of a given Feynman Integral in terms of simpler ones. Using this approach, we present, for the first time, results for a certain family of non-planar five-point two-loop Master Integrals with one external off-shell particle, relevant for instance for H + 2 jets production at the LHC, in both Euclidean and physical kinematical regions.

Jet charge in high-energy nuclear collisions * * This research is supported in part by the NSFC of China with Project Nos. 11935007 and 11435004

The averaged jet charge characterizes the electric charge of the initiating parton and provides a powerful tool to distinguish quark jets from gluon jets. We predict, for the first time, the medium modification of the averaged jet charge in the heavy-ion collisions at the LHC, where jet productions in p+p collisions are simulated by PYTHIA6, and the parton energy loss in QGP is calculated with two Monte Carlo models of jet quenching: PYQUEN and JEWEL. We found that the distribution of averaged jet charge is significantly suppressed by initial state isospin effects due to the participation of neutrons with zero electric charge during nuclear collisions. The considerable enhancement of the averaged jet charge in central Pb+Pb collisions is observed relative to peripheral collisions, since the jet quenching effect is more pronounced in central collisions. The distinct feature of the averaged jet charge between quark and gluon jets, along with the sensitivity of medium modifications on the jet charge to flavor dependence of the parton energy loss, could be very useful to discriminate the energy loss pattern between quark and gluon jets in heavy-ion collisions.

Next-to-leading power corrections to V+1 jet production in N -jettiness subtraction

We discuss the subleading power corrections to one-jet production processes in $N$-jettiness subtraction using vector-boson plus jet production as an example. We analytically derive the next-to-leading power leading logarithmic corrections (NLP-LL) through ${\cal O}(\alpha_S)$ in perturbative QCD, and outline the calculation of the next-to-leading logarithmic corrections (NLP-NLL). Our result is differential in the jet transverse momentum and rapidity, and in the vector boson momentum squared and rapidity. We present simple formulae that separate the NLP corrections into universal factors valid for any one-jet cross section and process-dependent matrix-element corrections. We discuss in detail features of the NLP corrections such as the process independence of the leading-logarithmic result that occurs due to the factorization of matrix elements in the subleading soft limit, the occurrence of poles in the non-hemisphere soft function at NLP and the cancellation of potential $\sqrt{\mathcal{T}_1/Q}$ corrections to the $N$-jettiness factorization theorem. We validate our analytic result by comparing them to numerically-fitted coefficients, finding good agreement for both the inclusive and the differential cross sections.