Related papers: Leptons in the Proton
The strong force which binds hadrons is described by the theory of Quantum Chromodynamics (QCD). Determining the character and manifestations of QCD is one of the most important and challenging outstanding issues necessary for a…
Under certain running conditions, the CERN Large Hadron Collider (LHC) can be considered as a photon-photon collider. Indeed, in proton-proton, proton-ion, ion-ion collisions, when incoming particles pass very close to each other in very…
Positron beams, both polarized and unpolarized, are identified as essential ingredients for the experimental program at the next generation of lepton accelerators. In the context of the Hadronic Physics program at the Jefferson Laboratory…
Deep inelastic scattering of $e^{\pm}$ off protons is sensitive to contributions from "dark photon" exchange. Using HERA data fit to HERA's parton distribution functions, we obtain the model-independent bound $\epsilon \lesssim 0.02$ on the…
We develop a unified algebraic model which satisfactorily describes the internal structure of pion and kaon as well as heavy quarkonia ($\eta_c$ and $\eta_b$). For each of these mesons, we compute their generalized parton distributions…
Several models of particle physics different from the Standard Model predict the existence of a dark sector that is weakly coupled to the visible one: the two sectors may couple via the vector portal, where a dark photon with mass in the…
At large values of x the parton distribution functions (PDFs) of the proton are poorly constrained and there are considerable variations between different global fits. Data at such high x have already been published by the ZEUS…
We present a physical model for polarized and unpolarized structure functions and parton density functions (PDFs) of the proton and the neutron. It reproduces the data on F_2^p(x,Q^2) for 0.00001<x<1 and 2.5<Q^2<5000 GeV^2,…
The inclusion of heavy neutral leptons to the Standard Model particle content could provide solutions to many open questions in particle physics and cosmology. The modification of the charged and neutral currents from active-sterile mixing…
A search for vector-like leptons in multilepton (two, three, or four-or-more electrons plus muons) final states with zero or more hadronic $\tau$-lepton decays is presented. The search is performed using a dataset corresponding to an…
The parton densities of the proton are of fundamental importance not only for our description of hadronic and nuclear structure, but also for reliable predictions for new heavy particle searches at colliders. At the large partonic momentum…
Parton distribution functions (PDFs) describe the inner, non-perturbative structure of hadrons. Their computation involves matrix elements with a Wilson line along a direction on the light cone, posing significant challenges in Euclidean…
Results are reported from a search for physics beyond-the-standard-model, such as supersymmetry, in final states with at least three charged leptons, in any combination of electrons or muons. The data sample corresponds to an integrated…
Unintegrated parton density functions (uPDFs) of Quantum Chromodynamics (QCD), also known as TMDPDFs, are generally used to study details of hadronic final states in high energy lepton-hadron and hadron-hadron collisions; while the…
A search for a heavy neutral lepton N of Majorana nature decaying into a W boson and a charged lepton is performed using the CMS detector at the LHC. The targeted signature consists of three prompt charged leptons in any flavor combination…
We point out a problem of the phenomenological definition of the valence partons as the difference between the partons and antipartons in the context of the NNLO evolution equations. After demonstrating that the classification of the parton…
High-precision measurements of Standard Model processes provide information on different aspects contributing to the process, such as parton distribution functions, and comparisons with the current precision reached theoretically on the…
In the framework of hypercolor extension of the Standard Model having vectorlike hyperquarks and two stable dark matter candidates originated from different hyper-currents, we consider some effects which result from reactions with…
As the value of the longitudinal momentum carried by partons in a ultra-relativistic hadron becomes small, one observes a growth of their density. When the parton density becomes close to a value of order $1/\alpha_s$, it does not grow any…
The Standard Model of particle physics has been remarkably successful in describing present experimental results. However, it is assumed to be only a low-energy effective theory which will break down at higher energy scales, theoretically…