Cone Jet Research Articles

QCD resummation for light-particle jets

We construct an evolution equation for the invariant-mass distribution of light-quark and gluon jets in the framework of QCD resummation. The solution of the evolution equation exhibits a behavior consistent with Tevatron CDF data: the jet distribution vanishes in the small invariant-mass limit, and its peak moves toward the high invariant-mass region with the jet energy. We also construct an evolution equation for the energy profile of the light-quark and gluon jets in the similar framework. The solution shows that the energy accumulates faster within a light-quark jet cone than within a gluon jet cone. The jet energy profile convoluted with hard scattering and parton distribution functions matches well with the Tevatron CDF and the large-hadron-collider (LHC) CMS data. Moreover, comparison with the CDF and CMS data implies that jets with large (small) transverse momentum are mainly composed of the light-quark (gluon) jets. At last, we discuss the application of the above solutions for the light-particle jets to the identification of highly-boosted heavy particles produced at LHC.

The minimum or natural rate of flow and droplet size ejected by Taylor cone–jets: physical symmetries and scaling laws

We aim to establish the scaling laws for both the minimum rate of flow attainable in the steady cone–jet mode of electrospray, and the size of the resulting droplets in that limit. Use is made of a small body of literature on Taylor cone–jets reporting precise measurements of the transported electric current and droplet size as a function of the liquid properties and flow rate. The projection of the data onto an appropriate non-dimensional parameter space maps a region bounded by the minimum rate of flow attainable in the steady state. To explain these experimental results, we propose a theoretical model based on the generalized concept of physical symmetry, stemming from the system time invariance (steadiness). A group of symmetries rising at the cone-to-jet geometrical transition determines the scaling for the minimum flow rate and related variables. If the flow rate is decreased below that minimum value, those symmetries break down, which leads to dripping. We find that the system exhibits two instability mechanisms depending on the nature of the forces arising against the flow: one dominated by viscosity and the other by the liquid polarity. In the former case, full charge relaxation is guaranteed down to the minimum flow rate, while in the latter the instability condition becomes equivalent to the symmetry breakdown by charge relaxation or separation. When cone–jets are formed without artificially imposing a flow rate, a microjet is issued quasi-steadily. The flow rate naturally ejected this way coincides with the minimum flow rate studied here. This natural flow rate determines the minimum droplet size that can be steadily produced by any electrohydrodynamic means for a given set of liquid properties.

Measurement of Multijet Ratios and a Determination ofαsat the Tevatron

In this poster we present several recent results for the prod uction of multijet final states in p ¯ p colli- sions at a center of mass energy of 1.96 TeV, taken with the DO experiment at the Fermilab Tevatron collider.. These measurements, defined as ratios of three-jet to two-je t quantities, reduce the dependence of the results on Parton Distribution Functions (PDFs) and experimental systematic uncertainties. Based on one of these ratio measurements, a value ofs is determined and the running ofs tested over a wide range of jet transverse momenta. p collisions at a center of mass energy of 1.96 TeV which were recorded with the DO experiment (2) at the Fermilab Tevatron collider. The data analyzed were recorded using a sin- gle jet triggers at a variety of thresholds, correspond- ing to an integrated luminosity of 0.7 fb−1. The event selection, jet reconstruction, jet energy and momentum corrections in these measurements follow closely those used in our recent measurements of inclusive jet and di- jet distributions(3-5). Jets are defined by the Run II mid- point cone jet algorithm (6) with a cone radius (for most jet studies) of Rcone = p (�y) 2 + (��) 2 = 0.7.

Development of 16 Nozzle Electrohydrodynamic Inkjet Printing Head

A micromachined electrohydrodynamic inkjet printing head has been fabricated out of glass wafer and stable patterning of uniform fine lines has been realized.We applied a sandblasting process on a glass wafer to fabricate tiny nozzles with a inner diameter of 60 microns and outer diameter of 100 microns. We observed a continuous cone jet mode at a DC bias voltage of 2 kV. Line patterns are printed with black carbon ink and the line width about 25 microns are achieved without any special surface treatment. The thickness of printed line was several hundred nanometers, which is much larger than that from conventional inkjet printing systems. Drop on demand printing up to 3 kHz was demonstrated also by applying pulse signals on a nozzle. Silver particle inks are also printed well and continuous line patterns are fabricated.

Assessment of In Situ Scour Profile in Sand Using a Jet Probe

Abstract Work in this paper presents a device and a process for in situ assessment of erosion potential with depth. The proposed device is termed “in situ erosion evaluation probe” (ISEEP), and the process is developed based upon advancing a rod fitted with a truncated cone jet nozzle into the soil. As water exits the nozzle with controllable velocity and flow rate (induced by an external pump) the probe advances into the subsurface profile and the rate of advancement is measured. The jet flow velocity and the advancement rate of the probe are correlated with a stream power value, and used to estimate soil erodibility parameters. Results from laboratory testing show the feasibility of the concept. An approach for the estimation of a critical stream power and a detachment rate coefficient is presented. Numerical modeling and deployment of the device at a North Carolina barrier island site after hurricane Irene are used to demonstrate the applicability of the proposed concept. Correlations between scour magnitudes, estimated by ISEEP parameters, and those estimated through modeling and field observation are presented and illustrate the viability of ISEEP’s soil erosion parameters as defined by a critical stream power and a detachment rate coefficient.

FRAME DRAGGING, DISK WARPING, JET PRECESSING, AND DIPPED X-RAY LIGHT CURVE OF Sw J1644+57

The X-ray transient source Sw J1644+57 recently discovered by Swift is believed to be triggered by tidal disruption of a star by a rapidly spinning supermassive black hole (SMBH). For such events, the outer disk is very likely misaligned with respect to the equatorial plane of the spinning SMBH, since the incoming star before disruption most likely has an inclined orbital plane. The tilted disk is subject to the Lense-Thirring torque, which tends to twist and warp due to the Bardeen-Petterson effect. The inner disk tends to align with the SMBH spin, while the outer region tends to remain in the stellar orbital plane, with a transition zone around the Bardeen-Petterson radius. The relativistic jet launched from the spinning SMBH would undergo precession. The 5-30 day X-ray lightcurve of Sw J1644+57 shows a quasi-periodic (2.7-day) variation with noticeable narrow dips. We numerically solve a warped disk and propose a jet-precessing model by invoking a Blandford-Znajek jet collimated by a wind launched near the Bardeen-Petterson radius. Through simulations, we show that the narrow dips in the X-ray lightcurve can be reproduced for a range of geometric configurations. From data we infer that the inclination angle of the initial stellar orbit is in the range of $10^{\circ}-20^{\circ}$ from the SMBH equatorial plane, that the jet should have a moderately high Lorentz factor, and that the inclination angle, jet opening angle, and observer's viewing angle are such that the duty cycle of the line-of-sight sweeping the jet cone is somewhat less than 0.5.

Structural, optical and electrical properties of tin oxide thin films by electrostatic spray deposition

Abstract Tin oxide (SnO2) thin films were deposited by electrostatic spray deposition (ESD). The structural, optical and electrical properties of the films for different solvents were studied. The morphology of the deposited thin films was investigated by scanning electron microscopy. The optical transmission spectra of the films showed 66–75% transmittance in the visible region of spectrum. The electrical resistivity of thin films deposited using the different solvents ranged 1.08 × 10−3–1.34 × 10−3 Ω-cm. Overall, EG and PG were good solvents for depositing SnO2 thin films by the ESD technique with stable cone jet.

Numerical simulation of the cone–jet formation and current generation in electrostatic spray—modeling as regards space charged droplet effect

A physical model of the electric field induced by charged droplets taking account of the effect of space charged droplet emitted from the tip of cone–jet to the external electric field is proposed. Combining this model with the fluid flow equations and charge conservation equation, the evolution of the cone–jet is simulated. The diameter of droplets emitted from the cone–jet tip and current on cone–jet are predicted at various applied voltages and flow rates. The calculated droplet diameter agrees well with experimental measurement. For low conductivity liquid, the droplet diameter decreases with the increment of applied voltage, but decreases with the reduction of flow rate. The simulation result also indicates that the current on the cone–jet increases linearly with the applied voltage. The electric field induced by charged droplets results in the decrease of the cone angle and the presence of space charged droplets has a non-negligible effect on the operation parameters.

Charged particle jet measurements with the ALICE experiment in proton-proton collisions at the LHC

We present preliminary results of measurements of charged particle jet properties in proton-proton collisions at = 7 TeV using the ALICE detector. Jets are reconstructed using anti - kT, kT and SISCone jet finding algorithms with resolution parameter R = 0.4 in the range of transverse momentum from 20 to 100 GeV/c in the midrapidity region (|η| < 0.5). The uncorrected charged jet spectra obtained using the three different jet finders show good agreement. The data are compared to predictions from PYTHIA-Perugia0, PYTHIA-Perugia2011, and PHOJET. The mean charged particle multiplicity in leading jets increases with increasing jet pT and is consistent with model predictions. The radial distributions of transverse momentum about the jet direction and the distributions of the average radius containing 80% of the total jet pT found in the jet cone (R = 0.4 in this analysis), indicate that high pT jets are more collimated than low pT jets.

Structural and electrical properties of P3HT:PCBM/PEDOT:PSS thin films deposited through electrohydrodynamic atomization technique

This paper presents the deposition of solution based composite P3HT:PCBM thin film on PEDOT:PSS coated ITO substrate via electrohydrodynamic atomization (EHDA) technique. Deposition conditions such as stable cone jet formation, flow rate and applied potential have been investigated. X-ray diffraction anlaysis revealed the presence of P3HT polymer in the as deposited film. Surface morphology investigated using a field emission-scanning electron microscope confirms that a uniform deposition of thin films was achieved. The current–voltage characteristics of the as deposited films show a rectifying behavior. The capacitance–voltage study indicated capacitance of the as deposited thin films depended on the frequency .

Measurement of jet fragmentation into charged particles in pp and PbPb collisions at $ \sqrt{{{s_{\mathrm{NN}}}}} = 2.76 $ TeV

Abstract Jet fragmentation in pp and PbPb collisions at a centre-of-mass energy of 2.76 TeV per nucleon pair was studied using data collected with the CMS detector at the LHC. Fragmentation functions are constructed using charged-particle tracks with transverse momenta p T &gt; 4 GeV/c for dijet events with a leading jet of p T &gt; 100 GeV/c. The fragmentation functions in PbPb events are compared to those in pp data as a function of collision centrality, as well as dijet-p T imbalance. Special emphasis is placed on the most central PbPb events including dijets with unbalanced momentum, indicative of energy loss of the hard scattered parent partons. The fragmentation patterns for both the leading and subleading jets in PbPb collisions agree with those seen in pp data at 2.76 TeV. The results provide evidence that, despite the large parton energy loss observed in PbPb collisions, the partition of the remaining momentum within the jet cone into high-p T particles is not strongly modified in comparison to that observed for jets in vacuum.

Jet mass with a jet veto at two loops and the universality of nonglobal structure

We investigate the exclusive jet mass distribution in ${e}^{+}{e}^{\ensuremath{-}}$ events, defined with a veto on the out-of-jet radiation, at two-loop order. In particular, we calculate the two-loop soft function, which is required to describe this distribution in the region of small jet mass. When combined with other ingredients using the soft-collinear effective theory, this generates the complete singular distribution for jet thrust, the sum of the jet masses, at two-loop order. The result is in excellent agreement with full quantum chromodynamics. The integrated jet thrust distribution is found to depend in an intricate way on both the finite jet cone size, $R$, and the jet veto scale. The result clarifies the structure of the potentially large logarithms (both global and nonglobal) which arise in jet observables for the first time at this order. Somewhat surprisingly, we find that, in the small $R$ limit, there is a precise and simple correspondence between the nonglobal contribution to the integrated jet thrust distribution and the previously calculated nonglobal contribution to the integrated hemisphere soft function, including subleading terms. This suggests that the small $R$ limit may provide a useful expansion for studying other exclusive jet substructure observables.

Numerical simulation of electrospray in the cone-jet mode

We present a robust and computationally efficient numerical scheme for simulating steady electrohydrodynamic atomization processes (electrospray). The main simplification assumed in this scheme is that all the free electrical charges are distributed over the interface. A comparison of the results with those calculated with a volume-of-fluid method showed that the numerical scheme presented here accurately describes the flow pattern within the entire liquid domain. Experiments were performed to partially validate the numerical predictions. The simulations reproduced accurately the experimental shape of the liquid cone jet, providing correct values of the emitted electric current even for configurations very close to the cone-jet stability limit.

Characterization of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) thin film deposited through electrohydrodynamic atomization technique

This article presents an attractive printing technique for thin film deposition of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) on flexible substrates known as electrohydrodynamic atomization (EHDA). Optimum flow rate and applied potential for stable cone jet mode has been confirmed through identification of process operating envelop. The uniformity and film thickness has been investigated by a field emission scanning electron microscope. The thin film shows nearly 75–82% transmittance in visible region. The electrical study shows good ohmic behavior of PEDOT:PSS thin film with the resistivity of approximately 49.6 mΩ cm.

The next-to-leading order forward jet vertex in the small-cone approximation

We consider within QCD collinear factorization the process p+p to jet + jet +X, where two forward high-$p_T$ jets are produced with a large separation in rapidity $\Delta y$ (Mueller-Navelet jets). In this case the (calculable) hard part of the reaction receives large higher-order corrections $\sim \alpha^n_s (\Delta y)^n$, which can be accounted for in the BFKL approach. In particular, we calculate in the next-to-leading order the impact factor (vertex) for the production of a forward high-$p_T$ jet, in the approximation of small aperture of the jet cone in the pseudorapidity-azimuthal angle plane. The final expression for the vertex turns out to be simple and easy to implement in numerical calculations.

Measurement and investigation on the deformation and air-assisted breakup of charged droplet

The present work concerns experimentally the deformation and breakup of charged droplet in the dripping mode. A high-speed camera combined with a microscopic zoom lens has been used to visualize the deformation and breakup morphology of charged droplet. Subsequently, a deformation rate which can describe the degree of deformation is used to study the effects of some parameters on charged droplet deformation. A home-made device has been designed and succeeds in calculating the tiny charge (nC) on a water droplet, and with the action of aerodynamic force the effect of charge on water droplet breakup is consequently obtained. The experiments show that at deformation stage the mediums with different conductivities will tend to have little effect on droplet deformation for the conductive liquids. Bigger surface tension produces a lower deformation rate and a higher voltage is needed to make the droplet change from the dripping mode to the cone–jet mode. Capillary diameter is also another key factor which influences the deformation rate, the deformation rate increases as the capillary diameter increases. Higher voltage implies a larger deformation rate for whatever mediums that have been tested. During the breakup stage the breakup time of charged droplets and the degree of bag elongation before breakup are all shorter than uncharged ones. Charged drop at low airflow velocity can gain quick breakup equal to uncharged drop of higher airflow velocity. That means breakup will be enhanced once droplets have been charged.

Maximizing boosted top identification by minimizing N-subjettiness

N-subjettiness is a jet shape designed to identify boosted hadronic objects such as top quarks. Given N subjet axes within a jet, N-subjettiness sums the angular distances of jet constituents to their nearest subjet axis. Here, we generalize and improve on N-subjettiness by minimizing over all possible subjet directions, using a new variant of the k-means clustering algorithm. On boosted top benchmark samples from the BOOST2010 workshop, we demonstrate that a simple cut on the 3-subjettiness to 2-subjettiness ratio yields 20% (50%) tagging efficiency for a 0.23% (4.1%) fake rate, making N-subjettiness a highly effective boosted top tagger. N-subjettiness can be modified by adjusting an angular weighting exponent, and we find that the jet broadening measure is preferred for boosted top searches. We also explore multivariate techniques, and show that additional improvements are possible using a modified Fisher discriminant. Finally, we briefly mention how our minimization procedure can be extended to the entire event, allowing the event shape N-jettiness to act as a fixed N cone jet algorithm.

Improved in situ Hf isotope ratio analysis of zircon using newly designed X skimmer cone and jet sample cone in combination with the addition of nitrogen by laser ablation multiple collector ICP-MS

The effect of three different cone combinations on the performance of laser ablation MC-ICP-MS (Neptune plus) for the in situ Hf isotope analysis of zircon were investigated. The signal sensitivities of Hf, Yb and Lu were improved by a factor of 1.4 and 2.5, respectively, with using the X skimmer cone + standard sampler cone and the X skimmer cone + Jet sample cone compared to the standard arrangement (H skimmer cone + standard sample cone). However, when using the high-sensitivity Jet sample cone, the instrumental mass fractionation for hafnium displayed a large non-linear component that could not be corrected using the normal mass fractionation laws. The magnitude of this non-linear mass fractionation was strongly related to the central gas flow rate. The in situ Hf isotope analysis of zircon standards 91500 and Mud Tank using the Jet cone displayed large deviations (410–470 ppm) at the optimum central gas flow rate for Hf, which seriously deteriorated the performance of the Jet cone. The addition of 4 ml min−1 nitrogen to the central gas flow in laser ablation MC-ICP-MS was found to not only increase the sensitivity of Hf by a factor of 2.1, but also suppress this non-linear mass fractionation. The determined Yb/Hf and Lu/Hf ratios at their corresponding optimum makeup gas flow rates for Hf intensity were found to be reduced by factors of 2 and 1.3 in the presence of nitrogen, respectively, which would benefit the accurate in situ determination of Hf isotopes in high-content Yb and Lu samples. Compared to the standard arrangement, the corresponding precision (2σ) of 176Hf/177Hf for single spot analysis of zircon standard 91500 was improved from 224 ppm to 50 ppm by using the newly designed X-skimmer cone and Jet sample cone in combination with the nitrogen addition technique. The determined 176Hf/177Hf ratios are in excellent agreement with published values in five reference zircon standards (91500, GJ-1, Mud Tank, Penglai and Plesovice). Our first Hf isotopic results from zircon standard M257 (0.281544 ± 0.000018; 2SD, n = 151) showed that it was fairly homogeneous in Hf isotopes. These results clearly demonstrate that the present analytical method has the potential to become an important tool for the pursuit of high-quality in situ Hf isotope data for zircons.

The SISCone jet algorithm optimised for low particle multiplicities

The SISCone jet algorithm is a seedless infrared-safe cone jet algorithm. There exists an implementation which is highly optimised for a large number of final state particles. However, in fixed-order perturbative calculations with a small number of final state particles, it turns out that the computer time needed for the jet clustering of this implementation is comparable to the computer time of the matrix elements. This article reports on an implementation of the SISCone algorithm optimised for low particle multiplicities. Program summary Program title: siscone_parton Catalogue identifier: AELF_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AELF_v1_0.html Program obtainable from: CPC Program Library, Queenʼs University, Belfast, N. Ireland Licensing provisions: GNU General Public License version 2 No. of lines in distributed program, including test data, etc.: 1588 No. of bytes in distributed program, including test data, etc.: 41 164 Distribution format: tar.gz Programming language: C++ Computer: All Operating system: All RAM: Negligible for low parton multiplicities. Classification: 11.9 Nature of problem: Clustering of particles into jets. Solution method: Infrared-safe cone algorithm. Restrictions: Hard-coded restriction to 64 final state particles on 64-bit machines, but recommended to be used only for configurations with up to 10 final state particles. Running time: Depending on the number of final state particles, O ( μs ) for configurations up to 5 final state particles.

Jet shower evolution in medium and dijet asymmetry in Pb+Pb collisions at the LHC

We study the evolution of a partonic jet shower propagating through a quark–gluon plasma. Combining the in-medium evolutions of the leading parton and shower gluons, we compute the depletion of the energy from the jet cone by dissipation through elastic collisions with medium constituents, by scattering of shower partons to larger angles and by radiation outside the jet cone. Numerical results are presented for the nuclear modification of dijet asymmetry in Pb+Pb collisions at the large hadron collider (LHC).