charged hadron
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Author(s):  
Matthew Klimek

Abstract We propose the study of the time substructure of jets, motivated by the fact that the next generation of detectors at particle colliders will resolve the time scale over which jet constituents arrive. This effect is directly related to the fragmentation and hadronization process, which transforms partons into massive hadrons with a distribution of velocities. We review the basic predictions for the velocity distribution of jet hadrons, and suggest an application for this information in the context of boosted object tagging. By noting that the velocity distribution is determined by the properties of the color string which ends on the parton that initiates the jet, we observe that jets originating from boosted color singlets, such as Standard Model electroweak bosons, will exhibit velocity distributions that are boosted relative to QCD jets of similar jet energy. We find that by performing a simple cut on the corresponding distribution of charged hadron arrival times at the detector, we can discriminate against QCD jets that would otherwise give a false positive under a traditional spatial substructure based boosted object tagger.


Author(s):  
P. Sahoo ◽  
U. Laha

Within the framework of non-relativistic quantum scattering theory we treat the charged hadron scattering by replacing the nuclear interaction by a separable nonlocal one and the electromagnetic part by the Manning-Rosen potential. The off-energy-shell scattering is studied by this additive interaction by including the effect of electromagnetic interaction rigorously. The exact analytical expressions for the off-shell solutions and half-shell T-matrix are obtained in maximal reduced form. The half-shell T-matrix for the proton-oxygen system is computed and the resultant phase shifts are found in order.


2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  

Abstract We present the first study of charged-hadron production associated with jets originating from b quarks in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data sample used in this study was collected with the CMS detector at the CERN LHC and corresponds to an integrated luminosity of 27.4 pb−1. To characterize the jet substructure, the differential jet shapes, defined as the normalized transverse momentum distribution of charged hadrons as a function of angular distance from the jet axis, are measured for b jets. In addition to the jet shapes, the per-jet yields of charged particles associated with b jets are also quantified, again as a function of the angular distance with respect to the jet axis. Extracted jet shape and particle yield distributions for b jets are compared with results for inclusive jets, as well as with the predictions from the pythia and herwig++ event generators.


2021 ◽  
Vol 36 (09) ◽  
pp. 2150062
Author(s):  
Çağın Kamışcıoğlu

KNO scaling was put forward by Koba, Nielsen, and Olesen (KNO) in 1972. Although it is an important tool for explaining multiplicity distributions and formulated for the asymptotic energies, it has been applied at a finite energy range where its formulation is not self-consistent. A consistent generalization, known as KNO-G scaling, was done by Golokhvastov in 1977 to make it self-consistent. Then, KNO-G scaling has been successfully applied in many experiments and its validity has been reported. In this study, KNO-G scaling is tested in neutrino interactions. The charged hadron multiplicity of CHORUS, OPERA, NOMAD and DONUT, which are neutrino experiments, is compared and tested the KNO-G scaling. It is observed that neutrino data are consistent with KNO-G scaling. A fit is superimposed on the data sets and fit parameters are compared.


2020 ◽  
Vol 80 (12) ◽  
Author(s):  
A. Aduszkiewicz ◽  
◽  
E. V. Andronov ◽  
T. Antićić ◽  
V. Babkin ◽  
...  

AbstractA measurement of charged hadron pair correlations in two-dimensional $$\Delta \eta \Delta \phi $$ Δ η Δ ϕ   space is presented. The analysis is based on total 30 million central Be + Be collisions observed in the NA61/SHINE detector at the CERN SPS for incident beam momenta of 19A, 30A, 40A, 75A, and 150A $$\text {Ge} \text {V}/c$$ Ge / c . Measurements were carried out for unlike-sign and like-sign charge hadron pairs independently. The $$C(\Delta \eta ,\Delta \phi )$$ C ( Δ η , Δ ϕ ) correlation functions were compared with results from a similar analysis on p + p interactions at similar beam momenta per nucleon. General trends of the back-to-back correlations are similar in central Be + Be collisions and p + p interactions, but are suppressed in magnitude due to the increased combinatorial background. Predictions from the Epos and UrQMD models are compared to the measurements. Evolution of an enhancement around $$(\Delta \eta ,\Delta \phi ) = (0,0)$$ ( Δ η , Δ ϕ ) = ( 0 , 0 ) with incident energy is observed in central Be + Be collisions. It is not predicted by both models and almost non-existing in proton–proton collisions at the same momentum per nucleon.


2020 ◽  
Vol 35 (39) ◽  
pp. 2050325
Author(s):  
Z. Ong ◽  
P. Agarwal ◽  
H. W. Ang ◽  
A. H. Chan ◽  
C. H. Oh

The full Giovannini parton branching equation is integrated numerically using the fourth-order Runge-Kutta method. Using a simple hadronization model, a charged-hadron multiplicity distribution is obtained. This model is then fitted to various experimental data up to the TeV scale to study how the Giovannini parameters vary with collision energy and type. The model is able to describe hadronic collisions up to the TeV scale and reveals the emergence of gluonic activity as the center-of-mass energy increases. A prediction is made for [Formula: see text].


Author(s):  
Vladimir Khachatryan ◽  
Michał Praszałowicz

Abstract A recent analysis from the PHENIX collaboration of available direct photon measurement results in collisions of various systems such as Au+Au, Cu+Cu, and Pb+Pb, at different beam energies ranging from 39 to 2760 GeV, has shown a universal, within experimental uncertainties, multiplicity scaling, in which direct photon $$p_{T}$$pT-spectra for transverse momenta up to 2 GeV/c are scaled with charged hadron pseudorapidity density at midrapidity raised to power $$\alpha =1.25$$α=1.25. On the other hand, those direct photon $$p_{T}$$pT-spectra also exhibit geometrical scaling in the similar $$p_{T}$$pT range. Assuming power-law dependence of the scaled photon spectra for both scaling laws, we formulate two independent conditions for the power $$\alpha $$α, which overshoot experimental data by $$\sim 10\%$$∼10% on average. We discuss possible sources that might improve this estimate.


Universe ◽  
2020 ◽  
Vol 6 (5) ◽  
pp. 61 ◽  
Author(s):  
Georg Wolschin

The rapid thermalization of quarks and gluons in the initial stages of relativistic heavy-ion collisions is treated using analytic solutions of a nonlinear diffusion equation with schematic initial conditions, and for gluons with boundary conditions at the singularity. On a similarly short time scale of t ≤ 1 fm/c, the stopping of baryons is accounted for through a QCD-inspired approach based on the parton distribution functions of valence quarks, and gluons. Charged-hadron production is considered phenomenologically using a linear relativistic diffusion model with two fragmentation sources, and a central gluonic source that rises with ln 3 ( s N N ) . The limiting-fragmentation conjecture that agrees with data at energies reached at the Relativistic Heavy-Ion Collider (RHIC) is found to be consistent with Large Hadron Collider (LHC) data for Pb-Pb at s N N = 2.76 and 5.02 TeV. Quarkonia are used as hard probes for the properties of the quark-gluon plasma (QGP) through a comparison of theoretical predictions with recent CMS, ALICE and LHCb data for Pb-Pb and p-Pb collisions.


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