S. Alekhin - DESY, Zeuthen & IHEP, Protvino

S. Alekhin
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Name
S. Alekhin
Affiliation
DESY, Zeuthen & IHEP, Protvino
City
Protvino
Country
Russia

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High Energy Physics - Phenomenology (47)
 
High Energy Physics - Experiment (24)
 
High Energy Physics - Lattice (3)
 
Physics - Accelerator Physics (2)
 
Nuclear Theory (2)
 
Nuclear Experiment (1)
 
Physics - Instrumentation and Detectors (1)

Publications Authored By S. Alekhin

We determine a new set of parton distribution functions (ABMP16), the strong coupling constant $\alpha_s$ and the quark masses $m_c$, $m_b$ and $m_t$ in a global fit to next-to-next-to-leading order (NNLO) in QCD. The analysis uses the $\overline{\mathrm{MS}}$ scheme for $\alpha_s$ and all quark masses and is performed in the fixed-flavor number scheme for $n_f=3, 4, 5$. Essential new elements of the fit are the combined data from HERA for inclusive deep-inelastic scattering (DIS), data from the fixed-target experiments NOMAD and CHORUS for neutrino-induced DIS, and data from Tevatron and the LHC for the Drell-Yan process and the hadro-production of single-top and top-quark pairs. Read More

We present a detailed study of nuclear corrections in the deuteron (D) from an analysis of data from charged-lepton deep-inelastic scattering (DIS) off proton and D, as well as from dimuon pair production in pp and pD collisions and $W^\pm$ and the $Z$ boson production at pp (p$\rm \bar p$) colliders. In particular, we discuss the determination of the off-shell function describing the modification of parton distributions (PDF) in bound nucleons in the context of global PDF fits. Our results are consistent with the ones obtained earlier from the study of the ratios of DIS structure functions $F_2^A/F_2^D$ in nuclei with $A\geq4$, confirming the universality of the off-shell function. Read More

The strong coupling constant $\alpha_s$ and the heavy-quark masses, $m_c$, $m_b$, $m_t$ are extracted simultaneosly with the parton distribution functions (PDFs) in the updated ABM12 fit including recent data from CERN-SPS, HERA, Tevatron, and the LHC. The values of \begin{eqnarray} \nonumber \alpha_s(M_Z)&=&0.1147\pm0. Read More

We present an update of the ABM12 PDF analysis including improved constraints due to the final version of the inclusive DIS HERA data, the Tevatron and LHC data on the W- and Z-production and those on heavy-quark production in the electron- and neutrino-induced DIS at HERA and the fixed-target experiments NOMAD and CHORUS. We also check the impact of the Tevatron and LHC top-quark production data on the PDFs and the strong coupling constant. We obtain $\alpha_s(M_Z)=0. Read More

We present a new determination of the top-quark mass $m_t$ based on the experimental data from the Tevatron and the LHC for single-top hadro-production. We use the inclusive cross sections of $s$- and $t$-channel top-quark production to extract $m_t$ and to minimize the dependence on the strong coupling constant and the gluon distribution in the proton compared to the hadro-production of top-quark pairs. As part of our analysis we compute the next-to-next-to-leading order approximation for the $s$-channel cross section in perturbative QCD based on the known soft-gluon corrections and implement it in the program Hathor for the numerical evaluation of the hadronic cross section. Read More

This report summarises the properties of Standard Model processes at the 100 TeV pp collider. We document the production rates and typical distributions for a number of benchmark Standard Model processes, and discuss new dynamical phenomena arising at the highest energies available at this collider. We discuss the intrinsic physics interest in the measurement of these Standard Model processes, as well as their role as backgrounds for New Physics searches. Read More

We use a fixed-order expansion of resummed soft-gluon corrections to determine an approximate NNLO formula for the partonic cross section of single-top production in the $s$-channel. This formula is implemented in the program Hathor for the numerical evaluation of hadronic cross sections. With the resulting code, we perform a fit of the top-quark mass to Tevatron cross section data. Read More

We review the present status of the determination of parton distribution functions (PDFs) in the light of the precision requirements for the LHC in Run 2 and other future hadron colliders. We provide brief reviews of all currently available PDF sets and use them to compute cross sections for a number of benchmark processes, including Higgs boson production in gluon-gluon fusion at the LHC. We show that the differences in the predictions obtained with the various PDFs are due to particular theory assumptions made in the fits of those PDFs. Read More

This document provides a writeup of all contributions to the workshop on "High precision measurements of $\alpha_s$: From LHC to FCC-ee" held at CERN, Oct. 12--13, 2015. The workshop explored in depth the latest developments on the determination of the QCD coupling $\alpha_s$ from 15 methods where high precision measurements are (or will be) available. Read More

We present an improved determination of the up- and down-quark distributions in the proton using recent data on charged lepton asymmetries from $W^\pm$ gauge-boson production at the LHC and Tevatron. The analysis is performed in the framework of a global fit of parton distribution functions. The fit results are consistent with a non-zero iso-spin asymmetry of the sea, $x(\bar d - \bar u)$, at small values of Bjorken $x\sim 10^{-4}$ indicating a delayed onset of the Regge asymptotics of a vanishing $(\bar d - \bar u)$-asymmetry at small-$x$. Read More

2015Apr

This paper describes the physics case for a new fixed target facility at CERN SPS. The SHiP (Search for Hidden Particles) experiment is intended to hunt for new physics in the largely unexplored domain of very weakly interacting particles with masses below the Fermi scale, inaccessible to the LHC experiments, and to study tau neutrino physics. The same proton beam setup can be used later to look for decays of tau-leptons with lepton flavour number non-conservation, $\tau\to 3\mu$ and to search for weakly-interacting sub-GeV dark matter candidates. Read More

We consider the impact of the recent data obtained by the LHC, Tevatron, and fixed-target experiments on the nucleon quark distributions with a particular focus on disentangling different quark species. An improved determination of the poorly known strange sea distribution is obtained due to including data from the neutrino-induced deep-inelastic scattering experiments NOMAD and CHORUS. The impact of the associated (W + c) production data by CMS and ATLAS on the strange sea determination is also studied and a comparison with earlier results based on the collider data is discussed. Read More

HERAFitter is an open-source package that provides a framework for the determination of the parton distribution functions (PDFs) of the proton and for many different kinds of analyses in Quantum Chromodynamics (QCD). It encodes results from a wide range of experimental measurements in lepton-proton deep inelastic scattering and proton-proton (proton-antiproton) collisions at hadron colliders. These are complemented with a variety of theoretical options for calculating PDF-dependent cross section predictions corresponding to the measurements. Read More

This report summarizes the proceedings of the 2014 Mainz Institute for Theoretical Physics (MITP) scientific program on "High precision fundamental constants at the TeV scale". The two outstanding parameters in the Standard Model dealt with during the MITP scientific program are the strong coupling constant $\alpha_s$ and the top-quark mass $m_t$. Lacking knowledge on the value of those fundamental constants is often the limiting factor in the accuracy of theoretical predictions. Read More

We present an improved determination of the strange sea distribution in the nucleon with constraints coming from the recent charm production data in neutrino-nucleon deep-inelastic scattering by the NOMAD and CHORUS experiments and from charged current inclusive deep-inelastic scattering at HERA. We demonstrate that the results are consistent with the data from the ATLAS and the CMS experiments on the associated production of $W^\pm$-bosons with $c$-quarks. We also discuss issues related to the recent strange sea determination by the ATLAS experiment using LHC collider data. Read More

We present a global fit of parton distributions at next-to-next-to-leading order (NNLO) in QCD. The fit is based on the world data for deep-inelastic scattering, fixed-target data for the Drell-Yan process and includes, for the first time, data from the Large Hadron Collider (LHC) for the Drell-Yan process and the hadro-production of top-quark pairs. The analysis applies the fixed-flavor number scheme for n_f=3,4,5, uses the MS-bar scheme for the strong coupling \alpha_s and the heavy-quark masses and keeps full account of the correlations among all non-perturbative parameters. Read More

We report on progress in the determination of the unpolarised nucleon PDFs within the ABM global fit framework. The data used in the ABM analysis are updated including the charm-production and the high-Q2 neutral-current samples obtained at the HERA collider, as well as the LHC data on the differential Drell-Yan cross-sections. An updated set of the PDFs with improved experimental and theoretical accuracy at small x is presented. Read More

We report recent experimental and theoretical progress concerning the heavy-quark electro-production in the context of the ABM11 parton distribution function (PDF) fit. In the updated ABM11 analysis, including the recent combined HERA charm data, the MSbar-values of the c-quark mass m_c(m_c)=1.24 +- 0. Read More

We describe the determination of the strong coupling constant $\alpha_s(M_Z^2)$ and of the charm-quark mass $m_c(m_c)$ in the $\bar{\rm MS}$-scheme, based on the QCD analysis of the unpolarized World deep-inelastic scattering data. At NNLO the values of $\alpha_s(M_Z^2)=0.1134\pm 0. Read More

We report on recent determinations of NNLO parton distributions and of $\alpha_s(M_Z)$ based on the world deep-inelastic data, supplemented by collider data. Some applications are discussed for semi-inclusive processes at the LHC. Read More

We report an updated version of the ABKM09 NNLO PDF fit, which includes the most recent HERA collider data on the inclusive cross sections and an improved treatment of the heavy-quark contribution to deep-inelastic scattering using advantages of the running-mass definition for the heavy quarks. The ABM11 PDFs obtained from the updated fit are in a good agreement with the recent LHC data on the W- and Z-production within the experimental and PDF uncertainties. We also perform a determination of the strong coupling constant \alpha_s in a variant of the ABM11 fit insensitive to the influence of the higher twist terms and find the value of \alpha_s=0. Read More

We present a determination of the charm-quark mass in the MSbar scheme using the data combination of charm production cross section measurements in deep-inelastic scattering at HERA. The framework of global analyses of the proton structure accounts for all correlations of the charm-quark mass with the other non-perturbative parameters, most importantly the gluon distribution function in the proton and the strong coupling constant alpha_s(M_Z). We obtain at next-to-leading order in QCD the value m_c(m_c) = 1. Read More

2012Nov
Authors: J. L. Abelleira Fernandez, C. Adolphsen, P. Adzic, A. N. Akay, H. Aksakal, J. L. Albacete, B. Allanach, S. Alekhin, P. Allport, V. Andreev, R. B. Appleby, E. Arikan, N. Armesto, G. Azuelos, M. Bai, D. Barber, J. Bartels, O. Behnke, J. Behr, A. S. Belyaev, I. Ben-Zvi, N. Bernard, S. Bertolucci, S. Bettoni, S. Biswal, J. Blümlein, H. Böttcher, A. Bogacz, C. Bracco, J. Bracinik, G. Brandt, H. Braun, S. Brodsky, O. Brüning, E. Bulyak, A. Buniatyan, H. Burkhardt, I. T. Cakir, O. Cakir, R. Calaga, A. Caldwell, V. Cetinkaya, V. Chekelian, E. Ciapala, R. Ciftci, A. K. Ciftci, B. A. Cole, J. C. Collins, O. Dadoun, J. Dainton, A. De. Roeck, D. d'Enterria, P. DiNezza, M. D'Onofrio, A. Dudarev, A. Eide, R. Enberg, E. Eroglu, K. J. Eskola, L. Favart, M. Fitterer, S. Forte, A. Gaddi, P. Gambino, H. García Morales, T. Gehrmann, P. Gladkikh, C. Glasman, A. Glazov, R. Godbole, B. Goddard, T. Greenshaw, A. Guffanti, V. Guzey, C. Gwenlan, T. Han, Y. Hao, F. Haug, W. Herr, A. Hervé, B. J. Holzer, M. Ishitsuka, M. Jacquet, B. Jeanneret, E. Jensen, J. M. Jimenez, J. M. Jowett, H. Jung, H. Karadeniz, D. Kayran, A. Kilic, K. Kimura, R. Klees, M. Klein, U. Klein, T. Kluge, F. Kocak, M. Korostelev, A. Kosmicki, P. Kostka, H. Kowalski, M. Kraemer, G. Kramer, D. Kuchler, M. Kuze, T. Lappi, P. Laycock, E. Levichev, S. Levonian, V. N. Litvinenko, A. Lombardi, J. Maeda, C. Marquet, B. Mellado, K. H. Mess, A. Milanese, J. G. Milhano, S. Moch, I. I. Morozov, Y. Muttoni, S. Myers, S. Nandi, Z. Nergiz, P. R. Newman, T. Omori, J. Osborne, E. Paoloni, Y. Papaphilippou, C. Pascaud, H. Paukkunen, E. Perez, T. Pieloni, E. Pilicer, B. Pire, R. Placakyte, A. Polini, V. Ptitsyn, Y. Pupkov, V. Radescu, S. Raychaudhuri, L. Rinolfi, E. Rizvi, R. Rohini, J. Rojo, S. Russenschuck, M. Sahin, C. A. Salgado, K. Sampei, R. Sassot, E. Sauvan, M. Schaefer, U. Schneekloth, T. Schörner-Sadenius, D. Schulte, A. Senol, A. Seryi, P. Sievers, A. N. Skrinsky, W. Smith, D. South, H. Spiesberger, A. M. Stasto, M. Strikman, M. Sullivan, S. Sultansoy, Y. P. Sun, B. Surrow, L. Szymanowski, P. Taels, I. Tapan, T. Tasci, E. Tassi, H. Ten. Kate, J. Terron, H. Thiesen, L. Thompson, P. Thompson, K. Tokushuku, R. Tomás García, D. Tommasini, D. Trbojevic, N. Tsoupas, J. Tuckmantel, S. Turkoz, T. N. Trinh, K. Tywoniuk, G. Unel, T. Ullrich, J. Urakawa, P. VanMechelen, A. Variola, R. Veness, A. Vivoli, P. Vobly, J. Wagner, R. Wallny, S. Wallon, G. Watt, C. Weiss, U. A. Wiedemann, U. Wienands, F. Willeke, B. -W. Xiao, V. Yakimenko, A. F. Zarnecki, Z. Zhang, F. Zimmermann, R. Zlebcik, F. Zomer

The present note relies on the recently published conceptual design report of the LHeC and extends the first contribution to the European strategy debate in emphasising the role of the LHeC to complement and complete the high luminosity LHC programme. The brief discussion therefore focuses on the importance of high precision PDF and $\alpha_s$ determinations for the physics beyond the Standard Model (GUTs, SUSY, Higgs). Emphasis is also given to the importance of high parton density phenomena in nuclei and their relevance to the heavy ion physics programme at the LHC. Read More

2012Nov
Authors: J. L. Abelleira Fernandez, C. Adolphsen, P. Adzic, A. N. Akay, H. Aksakal, J. L. Albacete, B. Allanach, S. Alekhin, P. Allport, V. Andreev, R. B. Appleby, E. Arikan, N. Armesto, G. Azuelos, M. Bai, D. Barber, J. Bartels, O. Behnke, J. Behr, A. S. Belyaev, I. Ben-Zvi, N. Bernard, S. Bertolucci, S. Bettoni, S. Biswal, J. Blümlein, H. Böttcher, A. Bogacz, C. Bracco, J. Bracinik, G. Brandt, H. Braun, S. Brodsky, O. Brüning, E. Bulyak, A. Buniatyan, H. Burkhardt, I. T. Cakir, O. Cakir, R. Calaga, A. Caldwell, V. Cetinkaya, V. Chekelian, E. Ciapala, R. Ciftci, A. K. Ciftci, B. A. Cole, J. C. Collins, O. Dadoun, J. Dainton, A. De. Roeck, D. d'Enterria, P. DiNezza, M. D'Onofrio, A. Dudarev, A. Eide, R. Enberg, E. Eroglu, K. J. Eskola, L. Favart, M. Fitterer, S. Forte, A. Gaddi, P. Gambino, H. García Morales, T. Gehrmann, P. Gladkikh, C. Glasman, A. Glazov, R. Godbole, B. Goddard, T. Greenshaw, A. Guffanti, V. Guzey, C. Gwenlan, T. Han, Y. Hao, F. Haug, W. Herr, A. Hervé, B. J. Holzer, M. Ishitsuka, M. Jacquet, B. Jeanneret, E. Jensen, J. M. Jimenez, J. M. Jowett, H. Jung, H. Karadeniz, D. Kayran, A. Kilic, K. Kimura, R. Klees, M. Klein, U. Klein, T. Kluge, F. Kocak, M. Korostelev, A. Kosmicki, P. Kostka, H. Kowalski, M. Kraemer, G. Kramer, D. Kuchler, M. Kuze, T. Lappi, P. Laycock, E. Levichev, S. Levonian, V. N. Litvinenko, A. Lombardi, J. Maeda, C. Marquet, B. Mellado, K. H. Mess, A. Milanese, J. G. Milhano, S. Moch, I. I. Morozov, Y. Muttoni, S. Myers, S. Nandi, Z. Nergiz, P. R. Newman, T. Omori, J. Osborne, E. Paoloni, Y. Papaphilippou, C. Pascaud, H. Paukkunen, E. Perez, T. Pieloni, E. Pilicer, B. Pire, R. Placakyte, A. Polini, V. Ptitsyn, Y. Pupkov, V. Radescu, S. Raychaudhuri, L. Rinolfi, E. Rizvi, R. Rohini, J. Rojo, S. Russenschuck, M. Sahin, C. A. Salgado, K. Sampei, R. Sassot, E. Sauvan, M. Schaefer, U. Schneekloth, T. Schörner-Sadenius, D. Schulte, A. Senol, A. Seryi, P. Sievers, A. N. Skrinsky, W. Smith, D. South, H. Spiesberger, A. M. Stasto, M. Strikman, M. Sullivan, S. Sultansoy, Y. P. Sun, B. Surrow, L. Szymanowski, P. Taels, I. Tapan, T. Tasci, E. Tassi, H. Ten. Kate, J. Terron, H. Thiesen, L. Thompson, P. Thompson, K. Tokushuku, R. Tomás García, D. Tommasini, D. Trbojevic, N. Tsoupas, J. Tuckmantel, S. Turkoz, T. N. Trinh, K. Tywoniuk, G. Unel, T. Ullrich, J. Urakawa, P. VanMechelen, A. Variola, R. Veness, A. Vivoli, P. Vobly, J. Wagner, R. Wallny, S. Wallon, G. Watt, C. Weiss, U. A. Wiedemann, U. Wienands, F. Willeke, B. -W. Xiao, V. Yakimenko, A. F. Zarnecki, Z. Zhang, F. Zimmermann, R. Zlebcik, F. Zomer

This document provides a brief overview of the recently published report on the design of the Large Hadron Electron Collider (LHeC), which comprises its physics programme, accelerator physics, technology and main detector concepts. The LHeC exploits and develops challenging, though principally existing, accelerator and detector technologies. This summary is complemented by brief illustrations of some of the highlights of the physics programme, which relies on a vastly extended kinematic range, luminosity and unprecedented precision in deep inelastic scattering. Read More

We analyse a tension between the D0 and CDF inclusive jet data and the perturbative QCD calculations, which are based on the ABKM09 and ABM11 parton distribution functions (PDFs) within the nuisance parameter framework. Particular attention is paid on the uncertainties in the nuisance parameters due to the data fluctuations and the PDF errors. We show that with account of these uncertainties the nuisance parameters do not demonstrate a statistically significant excess. Read More

We determine the charm-quark mass mc(mc) in the MS-bar scheme using measurements of charm production in deep-inelastic ep scattering at HERA in the kinematic range of photon virtuality from 5 to 1000 GeV squared and Bjorken scaling variable from 0.0001 to 0.5. Read More

We present a determination of the nucleon parton distribution functions (PDFs) and of the strong coupling constant $\alpha_s$ at next-to-next-to-leading order (NNLO) in QCD based on the world data for deep-inelastic scattering and the fixed-target data for the Drell-Yan process. The analysis is performed in the fixed-flavor number scheme for $n_f=3,4,5$ and uses the $\bar{MS}$ scheme for $\alpha_s$ and the heavy quark masses. The fit results are compared with other PDFs and used to compute the benchmark cross sections at hadron colliders to the NNLO accuracy. Read More

The ATLAS and CMS experiments observed a particle at the LHC with a mass $\approx 126$ GeV, which is compatible with the Higgs boson of the Standard Model. A crucial question is, if for such a Higgs mass value, one could extrapolate the model up to high scales while keeping the minimum of the scalar potential that breaks the electroweak symmetry stable. Vacuum stability requires indeed the Higgs boson mass to be $M_H \gsim 129 \pm 1$ GeV, but the precise value depends critically on the input top quark pole mass which is usually taken to be the one measured at the Tevatron, $m_t^{\rm exp}=173. Read More

2012Jun
Authors: J. L. Abelleira Fernandez, C. Adolphsen, A. N. Akay, H. Aksakal, J. L. Albacete, S. Alekhin, P. Allport, V. Andreev, R. B. Appleby, E. Arikan, N. Armesto, G. Azuelos, M. Bai, D. Barber, J. Bartels, O. Behnke, J. Behr, A. S. Belyaev, I. Ben-Zvi, N. Bernard, S. Bertolucci, S. Bettoni, S. Biswal, J. Blümlein, H. Böttcher, A. Bogacz, C. Bracco, G. Brandt, H. Braun, S. Brodsky, O. Brüning, E. Bulyak, A. Buniatyan, H. Burkhardt, I. T. Cakir, O. Cakir, R. Calaga, V. Cetinkaya, E. Ciapala, R. Ciftci, A. K. Ciftci, B. A. Cole, J. C. Collins, O. Dadoun, J. Dainton, A. De. Roeck, D. d'Enterria, A. Dudarev, A. Eide, R. Enberg, E. Eroglu, K. J. Eskola, L. Favart, M. Fitterer, S. Forte, A. Gaddi, P. Gambino, H. García Morales, T. Gehrmann, P. Gladkikh, C. Glasman, R. Godbole, B. Goddard, T. Greenshaw, A. Guffanti, V. Guzey, C. Gwenlan, T. Han, Y. Hao, F. Haug, W. Herr, A. Hervé, B. J. Holzer, M. Ishitsuka, M. Jacquet, B. Jeanneret, J. M. Jimenez, J. M. Jowett, H. Jung, H. Karadeniz, D. Kayran, A. Kilic, K. Kimura, M. Klein, U. Klein, T. Kluge, F. Kocak, M. Korostelev, A. Kosmicki, P. Kostka, H. Kowalski, G. Kramer, D. Kuchler, M. Kuze, T. Lappi, P. Laycock, E. Levichev, S. Levonian, V. N. Litvinenko, A. Lombardi, J. Maeda, C. Marquet, S. J. Maxfield, B. Mellado, K. H. Mess, A. Milanese, S. Moch, I. I. Morozov, Y. Muttoni, S. Myers, S. Nandi, Z. Nergiz, P. R. Newman, T. Omori, J. Osborne, E. Paoloni, Y. Papaphilippou, C. Pascaud, H. Paukkunen, E. Perez, T. Pieloni, E. Pilicer, B. Pire, R. Placakyte, A. Polini, V. Ptitsyn, Y. Pupkov, V. Radescu, S. Raychaudhuri, L. Rinolfi, R. Rohini, J. Rojo, S. Russenschuck, M. Sahin, C. A. Salgado, K. Sampei, R. Sassot, E. Sauvan, U. Schneekloth, T. Schörner-Sadenius, D. Schulte, A. Senol, A. Seryi, P. Sievers, A. N. Skrinsky, W. Smith, H. Spiesberger, A. M. Stasto, M. Strikman, M. Sullivan, S. Sultansoy, Y. P. Sun, B. Surrow, L. Szymanowski, P. Taels, I. Tapan, A. T. Tasci, E. Tassi, H. Ten. Kate, J. Terron, H. Thiesen, L. Thompson, K. Tokushuku, R. Tomás García, D. Tommasini, D. Trbojevic, N. Tsoupas, J. Tuckmantel, S. Turkoz, T. N. Trinh, K. Tywoniuk, G. Unel, J. Urakawa, P. VanMechelen, A. Variola, R. Veness, A. Vivoli, P. Vobly, J. Wagner, R. Wallny, S. Wallon, G. Watt, C. Weiss, U. A. Wiedemann, U. Wienands, F. Willeke, B. -W. Xiao, V. Yakimenko, A. F. Zarnecki, Z. Zhang, F. Zimmermann, R. Zlebcik, F. Zomer

The physics programme and the design are described of a new collider for particle and nuclear physics, the Large Hadron Electron Collider (LHeC), in which a newly built electron beam of 60 GeV, up to possibly 140 GeV, energy collides with the intense hadron beams of the LHC. Compared to HERA, the kinematic range covered is extended by a factor of twenty in the negative four-momentum squared, $Q^2$, and in the inverse Bjorken $x$, while with the design luminosity of $10^{33}$ cm$^{-2}$s$^{-1}$ the LHeC is projected to exceed the integrated HERA luminosity by two orders of magnitude. The physics programme is devoted to an exploration of the energy frontier, complementing the LHC and its discovery potential for physics beyond the Standard Model with high precision deep inelastic scattering measurements. Read More

We discuss the heavy-quark contribution to deep inelastic scattering in the scheme with $n_f=3,4,5$ fixed flavors. Based on the recent ABM11 PDF analysis of world data for deep-inelastic scattering and fixed-target data for the Drell-Yan process with the running-mass definition for heavy quarks we show that fixed flavor number scheme is sufficient for describing the deep-inelastic-scattering data in the entire kinematic range. We compare with other PDF sets and comment on the implications for measuring the strong coupling constant $\alpha_s(M_Z)$. Read More

We present a determination of parton distribution functions (ABM11) and the strong coupling constant alpha_s at next-to-leading order and next-to-next-to-leading order (NNLO) in QCD based on world data for deep-inelastic scattering and fixed-target data for the Drell-Yan process. The analysis is performed in the fixed-flavor number scheme for n_f=3,4,5 and uses the MSbar-scheme for alpha_s and the heavy-quark masses. At NNLO we obtain the value alpha_s(M_Z) = 0. Read More

2012Jan
Authors: LHC Higgs Cross Section Working Group, S. Dittmaier1, C. Mariotti2, G. Passarino3, R. Tanaka4, S. Alekhin, J. Alwall, E. A. Bagnaschi, A. Banfi, J. Blumlein, S. Bolognesi, N. Chanon, T. Cheng, L. Cieri, A. M. Cooper-Sarkar, M. Cutajar, S. Dawson, G. Davies, N. De Filippis, G. Degrassi, A. Denner, D. D'Enterria, S. Diglio, B. Di Micco, R. Di Nardo, R. K. Ellis, A. Farilla, S. Farrington, M. Felcini, G. Ferrera, M. Flechl, D. de Florian, S. Forte, S. Ganjour, M. V. Garzelli, S. Gascon-Shotkin, S. Glazov, S. Goria, M. Grazzini, J. -Ph. Guillet, C. Hackstein, K. Hamilton, R. Harlander, M. Hauru, S. Heinemeyer, S. Hoche, J. Huston, C. Jackson, P. Jimenez-Delgado, M. D. Jorgensen, M. Kado, S. Kallweit, A. Kardos, N. Kauer, H. Kim, M. Kovac, M. Kramer, F. Krauss, C. -M. Kuo, S. Lehti, Q. Li, N. Lorenzo, F. Maltoni, B. Mellado, S. O. Moch, A. Muck, M. Muhlleitner, P. Nadolsky, P. Nason, C. Neu, A. Nikitenko, C. Oleari, J. Olsen, S. Palmer, S. Paganis, C. G. Papadopoulos, T . C. Petersen, F. Petriello, F. Petrucci, G. Piacquadio, E. Pilon, C. T. Potter, J. Price, I. Puljak, W. Quayle, V. Radescu, D. Rebuzzi, L. Reina, J. Rojo, D. Rosco, G. P. Salam, A. Sapronov, J. Schaarschmidt, M. Schonherr, M. Schumacher, F. Siegert, P. Slavich, M. Spira, I. W. Stewart, W. J. Stirling, F. Stockli, C. Sturm, F. J. Tackmann, R. S. Thorne, D. Tommasini, P. Torrielli, F. Tramontano, Z. Trocsanyi, M. Ubiali, S. Uccirati, M. Vazquez Acosta, T. Vickey, A. Vicini, W. J. Waalewijn, D. Wackeroth, M. Warsinsky, M. Weber, M. Wiesemann, G. Weiglein, J. Yu, G. Zanderighi
Affiliations: 1eds., 2eds., 3eds., 4eds.

This Report summarises the results of the second year's activities of the LHC Higgs Cross Section Working Group. The main goal of the working group was to present the state of the art of Higgs Physics at the LHC, integrating all new results that have appeared in the last few years. The first working group report Handbook of LHC Higgs Cross Sections: 1. Read More

2011Aug
Authors: D. Boer, M. Diehl, R. Milner, R. Venugopalan, W. Vogelsang, A. Accardi, E. Aschenauer, M. Burkardt, R. Ent, V. Guzey, D. Hasch, K. Kumar, M. A. C. Lamont, Y. Li, W. J. Marciano, C. Marquet, F. Sabatie, M. Stratmann, F. Yuan, S. Abeyratne, S. Ahmed, C. Aidala, S. Alekhin, M. Anselmino, H. Avakian, A. Bacchetta, J. Bartels, H. BC, J. Beebe-Wang, S. Belomestnykh, I. Ben-Zvi, G. Beuf, J. Blumlein, M . Blaskiewicz, A. Bogacz, S. J. Brodsky, T. Burton, R. Calaga, X. Chang, I. O. Cherednikov, P. Chevtsov, G. A. Chirilli, C. Ciofi degli Atti, I. C. Cloet, A. Cooper-Sarkar, R. Debbe, Ya. Derbenev, A. Deshpande, F. Dominguez, A. Dumitru, R. Dupre, B. Erdelyi, C. Faroughy, S. Fazio, A. Fedotov, J. R. Forshaw, R. Geraud, K. Gallmeister, L. Gamberg, J. -H. Gao, D. Gassner, F. Gelis, G. P. Gilfoyle, G. Goldstein, K. Golec-Biernat, V. P. Goncalves, M. Gonderinger, M. Guzzi, P. Hagler, H. Hahn, L. Hammons, Y. Hao, P. He, T. Horn, W. A. Horowitz, M. Huang, A. Hutton, B. Jager, W. Jackson, A. Jain, E. C. Johnson, Z. -B. Kang, L. P. Kaptari, D. Kayran, J. Kewisch, Y. Koike, A. Kondratenko, B. Z. Kopeliovich, Y. V. Kovchegov, G. Krafft, P. Kroll, S. Kumano, K. Kumericki, T. Lappi, T. Lautenschlager, R. Li, Z. -T. Liang, V. N. Litvinenko, S. Liuti, Y. Luo, D. Muller, G. Mahler, A. Majumder, S. Manikonda, F. Marhauser, G. McIntyre, M. Meskauskas, W. Meng, A. Metz, C. B. Mezzetti, G. A. Miller, M. Minty, S. -O. Moch, V. Morozov, U. Mosel, L. Motyka, H. Moutarde, P. J. Mulders, B. Musch, P. Nadel-Turonski, P. Nadolsky, F. Olness, P. N. Ostrumov, B. Parker, B. Pasquini, K. Passek-Kumericki, A. Pikin, F. Pilat, B. Pire, H. Pirner, C. Pisano, E. Pozdeyev, A. Prokudin, V. Ptitsyn, X. Qian, J. -W. Qiu, M. Radici, A. Radyushkin, T. Rao, R. Rimmer, F. Ringer, S. Riordan, T. Rogers, J. Rojo, T. Roser, R. Sandapen, R. Sassot, T. Satogata, H. Sayed, A. Schafer, G. Schnell, P. Schweitzer, B. Sheehy, J. Skaritka, G. Soyez, M. Spata, H. Spiesberger, A. M. Stasto, N. G. Stefanis, M. Strikman, M. Sullivan, L. Szymanowski, K. Tanaka, S. Taneja, S. Tepikian, B. Terzic, Y. Than, T. Toll, D. Trbojevic, E. Tsentalovich, N. Tsoupas, K. Tuchin, J. Tuozzolo, T. Ullrich, A. Vossen, S. Wallon, G. Wang, H. Wang, X. -N. Wang, S. Webb, C. Weiss, Q. Wu, B. -W. Xiao, W. Xu, B. Yunn, A. Zelenski, Y. Zhang, J. Zhou, P. Zurita

This report is based on a ten-week program on "Gluons and the quark sea at high-energies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics. This report is organized around four major themes: i) the spin and flavor structure of the proton, ii) three-dimensional structure of nucleons and nuclei in momentum and configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and the search for physics beyond the Standard Model. Read More

We report on determinations of the running mass for charm quarks from deep-inelastic scattering reactions. The method provides complementary information on this fundamental parameter from hadronic processes with space-like kinematics. The obtained values are consistent with but systematically lower than the world average as published by the PDG. Read More

We study the impact of Tevatron jet data on a global fit of parton distribution functions and on the determination of the value of the strong coupling constant. The consequences are illustrated for cross sections of Higgs boson production at Tevatron and the LHC. Read More

The constraints of fixed-target DIS data in fits of parton distributions including QCD corrections to next-to-next-to leading order are studied. We point out a potential problem in the analysis of the NMC data which can lead to inconsistencies in the extracted value for alpha_s(M_Z) and the gluon distribution at higher orders in QCD. The implications for predictions of rates for Standard Model Higgs boson production at hadron colliders are investigated. Read More

This document is intended as a study of benchmark cross sections at the LHC (at 7 TeV) at NLO using modern parton distribution functions currently available from the 6 PDF fitting groups that have participated in this exercise. It also contains a succinct user guide to the computation of PDFs, uncertainties and correlations using available PDF sets. A companion note, also submitted to the archive, provides an interim summary of the current recommendations of the PDF4LHC working group for the use of parton distribution functions and of PDF uncertainties at the LHC, for cross section and cross section uncertainty calculations. Read More

The inclusive production cross sections for $W^+, W^-$ and $Z^0$-bosons form important benchmarks for the physics at hadron colliders. We perform a detailed comparison of the predictions for these standard candles based on recent next-to-next-to-leading order (NNLO) parton parameterizations and new analyses including the combined HERA data, compare to all available experimental results, and discuss the predictions for present and upcoming RHIC, SPS, Tevatron and LHC energies. The rates for gauge boson production at the LHC can be rather confidently predicted with an accuracy of better than about 10% at NNLO. Read More

We study the production of heavy quarks in deep-inelastic scattering within perturbative QCD. As a novelty, we employ for the first time the running mass definition in the MSbar scheme for deep-inelastic charm and bottom production. We observe an improved stability of the perturbative expansion and a reduced theoretical uncertainty due to variations of the renormalization and factorization scales. Read More

2010Sep

Recent experimental and theoretical results presented in the working group "Parton densities from DIS and hadron colliders to LHC" at the DIS2010 workshop are summarized in this contribution. Read More

I review the current status of the nucleon PDFs determined from global fits with emphasis on the impact of recent experimental data and the remaining theoretical challenges. Read More

We report on an update of the next-to-next-to-leading order (NNLO) ABKM09 parton distributions functions. They are obtained with the use of the combined HERA collider Run I inclusive deep-inelastic scattering (DIS) data and the partial NNLO corrections to the heavy quark electro-production taken into account. The value of the strong couplig constant $\alpha^{\rm NNLO}_{\rm s}(M_{\rm Z})=0. Read More

We perform QCD fit of the nucleon strange and anti-strange sea distributions to the neutrino and anti-neutrino dimuon data by the CCFR and NuTeV collaborations, supplemented by the inclusive charged lepton-nucleon Deep Inelastic Scattering (DIS) and Drell-Yan data. The effective semi-leptonic charmed-hadron branching ratio is constrained from the inclusive charmed hadron measurements performed by the FNAL-E531 and CHORUS neutrino emulsion experiments as $B_\mu=(8.8\pm0. Read More

We check the impact of the factorization scheme employed in the calculation of the heavy-quark deep-inelastic scattering (DIS) electro-production on the PDFs determined in the NNLO QCD analysis of the world inclusive neutral-current DIS data combined with the ones on the neutrino-nucleon DIS di-muon production and the fixed-target Drell-Yan process. The charm-quark DIS contribution is calculated in the general-mass variable-flavor-number (GMVFN) scheme: At asymptotically large values of the momentum transfer $Q$ it is given by the zero-mass 4-flavor scheme and at the value of $Q$ equal to the charm-quark mass it is smoothly matched with the 3-flavor scheme using the Buza-Matiounine-Smith-van Neerven prescription. The PDFs obtained in this variant of the fit are very similar to the ones obtained in the fit with a 3-flavor scheme employed. Read More

We determine the parton distribution functions (PDFs) in a next-to-next-to-leading order (NNLO) QCD-analysis of the inclusive neutral-current deep-inelastic-scattering (DIS) world data combined with the neutri{-}no-nucleon DIS di-muon data and the fixed-target Drell-Yan data. The PDF-evolution is performed in the $N_f = 3$ fixed-flavor scheme and supplementary sets of PDFs in the 4- and 5-flavor schemes are derived from the results in the 3-flavor scheme using matching conditions. The charm-quark DIS contribution is calculated in a general-mass variable-flavor-number (GMVFN) scheme interpolating between the zero-mass 4-flavor scheme at asymptotically large values of momentum transfer $Q^2$ and the 3-flavor scheme prescription of Buza-Matiounine-Smith-van Neerven (BMSN) at the value of $Q^2 = m_c^2$. Read More

We present an analysis of the nucleon strange sea extracted from a global Parton Distribution Function fit including the neutrino and anti-neutrino dimuon data by the CCFR and NuTeV collaborations, the inclusive charged lepton-nucleon Deep Inelastic Scattering and Drell-Yan data. The (anti-)neutrino induced dimuon analysis is constrained by the semi-leptonic charmed-hadron branching ratio $B_\mu=(8.8\pm0. Read More

We study the perturbative QCD corrections to heavy-quark structure functions of charged-lepton deep-inelastic scattering and their impact on global fits of parton distributions. We include the logarithmically enhanced terms near threshold due to soft gluon resummation in the QCD corrections at next-to-next-to-leading order. We demonstrate that this approximation is sufficient to describe the available HERA data in most parts of the kinematic region. Read More

We perform the next-to-next-leading-order (NNLO) QCD global fit of PDFs using inclusive charged-lepton and neutrino DIS data down to Q = 1 GeV. We also consider the data on neutrino-nucleon dimuon production, that allows us to disentangle the strange sea distribution. The fit results in \chi^2/NDP = 5150/4338 = 1. Read More