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We apply Bayesian inference to determine the posterior likelihood distribution for the parameters describing the initial condition of the small-$x$ Balitsky-Kovchegov evolution equation at leading logarithmic accuracy. The HERA structure…

High Energy Physics - Phenomenology · Physics 2024-03-13 Carlisle Casuga , Mikko Karhunen , Heikki Mäntysaari

We present the first unbiased determination of spin-dependent, or polarized, Parton Distribution Functions (PDFs) of the proton. A statistically sound representation of the corresponding uncertainties is achieved by means of the NNPDF…

High Energy Physics - Phenomenology · Physics 2014-03-04 Emanuele Roberto Nocera

Sets of parton distribution functions (PDFs) of the proton are reported for the leading (LO), next-to-leading (NLO) and next-to-next-to leading order (NNLO) QCD calculations. The parton distribution functions are determined with the…

In this talk we summarize main results of a recent determination of the polarized deeply inelastic parton distributions to NLO from the world data. In the analysis the LO and NLO parton densities and their $1\sigma$ statistical errors were…

High Energy Physics - Phenomenology · Physics 2015-06-25 J. Blümlein , H. Böttcher

Employing the representation of the experimental data on deep inelastic electron-proton scattering (DIS) in the color-dipole picture (CDP), we determine the gluon distribution of the proton at small Bjorken $x$. At sufficiently large…

High Energy Physics - Phenomenology · Physics 2025-12-02 G. R. Boroun , M. Kuroda , Dieter Schildknecht

Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has…

High Energy Physics - Phenomenology · Physics 2007-05-23 S. Kuhlmann , J. Huston , J. Morfin , F. Olness , J. Pumplin , J. F. Owens , W. K. Tung , J. J. Whitmore

We determine the infrared behaviour of the BFKL forward amplitude for gluon-gluon scattering. Our approach, based on the discrete pomeron solution, leads to an excellent description of the new combined inclusive HERA data at low values of x…

High Energy Physics - Phenomenology · Physics 2010-12-14 H. Kowalski , L. N. Lipatov , D. A. Ross , G. Watt

In the past year, polarized deep inelastic scattering experiments at CERN and SLAC have obtained structure function measurements off proton, neutron and deuteron targets at a level of precision never before achieved. The measurements can be…

High Energy Physics - Phenomenology · Physics 2010-04-06 T. Gehrmann , W. J. Stirling

We describe preliminary results from an effort to quantify the uncertainties in parton distribution functions and the resulting uncertainties in predicted physical quantities. The production cross section of the $W$ boson is given as a…

High Energy Physics - Phenomenology · Physics 2007-05-23 R. Brock , D. Casey , J. Huston , J. Kalk , J. Pumplin , D. Stump , W. K. Tung

To investigate the possible geometric structure of the proton, an improved stringy proton model is constructed beyond the smallest distance approximation, where the constituent quarks are connected by gluon tubes which merge at the Fermat…

High Energy Physics - Phenomenology · Physics 2024-06-19 Wenchang Xiang , Yanbing Cai , Mengliang Wang , Daicui Zhou

A discussion is presented of the manner in which uncertainties in parton distributions and related quantities are determined. One of the central problems is the criteria used to judge what variation of the parameters describing a set of…

High Energy Physics - Phenomenology · Physics 2008-11-26 R. S. Thorne , H. Boettcher , A. M. Cooper-Sarkar , B. Reisert , V. Shekelyan , W. J. Stirling , D. R. Stump , A. Vogt

We obtain the gluon parton distribution functions (PDFs) in the proton within the extended light-front holographic QCD framework, where the proton couples with the spin-two Pomeron in Anti-de Sitter space, together with constraints imposed…

High Energy Physics - Phenomenology · Physics 2023-03-29 Bheemsehan Gurjar , Chandan Mondal , Dipankar Chakrabarti

Precise determinations of the strong coupling constant in hadronic collisions demand sets of parton densities spanning a sufficiently wide range of values for the QCD scale parameter Lambda. For such applications, we supplement the recent…

High Energy Physics - Phenomenology · Physics 2009-10-28 A. Vogt

We propose a physically motivated parametrization for the unpolarized generalized parton distributions, H and E, valid at both zero and non-zero values of the skewness variable, \zeta. At \zeta=0, H and E are determined using constraints…

High Energy Physics - Phenomenology · Physics 2017-08-23 S. Ahmad , H. Honkanen , S. Liuti , S. K. Taneja

Measurements of the diffractive structure function, $F_2^D$, of the proton at HERA are used to extract the partonic structure of the Pomeron. Regge Factorization is tested and is found to describe well the existing data within the selected…

High Energy Physics - Phenomenology · Physics 2011-07-19 Halina Abramowicz , Michael Groys , Aharon Levy

Taking proton as an ensemble of quark-gluon Fock states and using the principle of detailed balance, we construct a simple statistical model for parton distribution of proton. The recent observed Bjorken-$x$ dependent light flavor sea quark…

High Energy Physics - Phenomenology · Physics 2009-11-07 Yong-Jun Zhang , Bing-Song Zou , Li-Ming Yang

We present here some arguments to support our suggestion that data on the helicity structure for the hard exclusive electroproduction of $\rho$ mesons at HERA (and in possible future high-energy electron-proton colliders) provide useful…

High Energy Physics - Phenomenology · Physics 2019-01-14 Andrèe Dafne Bolognino , Francesco Giovanni Celiberto , Dmitry Yu. Ivanov , Alessandro Papa

Parametrization of nuclear parton distributions is investigated in the leading order of alpha_s. The parton distributions are provided at Q^2=1 GeV^2 with a number of parameters, which are determined by a chi^2 analysis of the data on…

High Energy Physics - Phenomenology · Physics 2009-11-07 M. Hirai , S. Kumano , M. Miyama

The physics scope of a possible future experiment utilizing an internal polarized nucleon target in the HERA proton beam is discussed. By measuring single spin asymmetries in inclusive particle production at 820~GeV beam energy the…

High Energy Physics - Phenomenology · Physics 2007-05-23 Wolf-Dieter Nowak

We review the latest information that is available about the parton distributions of the proton, paying particular attention to the determination of the gluon. We briefly describe the various processes that have been advocated to be a…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. D. Martin