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Records |
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Author |
Rinaldi, M.; Scopetta, S.; Traini, M.; Vento, V. |
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Title |
Correlations in double parton distributions: perturbative and non-perturbative effects |
Type |
Journal Article |
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Year |
2016 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
10 |
Issue |
10 |
Pages |
063 - 36pp |
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Keywords |
Deep Inelastic Scattering (Phenomenology); Phenomenological Models |
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Abstract |
The correct description of Double Parton Scattering (DPS), which represents a background in several channels for the search of new Physics at the LHC, requires the knowledge of double parton distribution functions (dPDFs). These quantities represent also a novel tool for the study of the three-dimensional nucleon structure, complementary to the possibilities offered by electromagnetic probes. In this paper we analyze dPDFs using Poincare covariant predictions obtained by using a Light-Front constituent quark model proposed in a recent paper, and QCD evolution. We study to what extent factorized expressions for dPDFs, which neglect, at least in part, two-parton correlations, can be used. We show that they fail in reproducing the calculated dPDFs, in particular in the valence region. Actually measurable processes at existing facilities occur at low longitudinal momenta of the interacting partons; to have contact with these processes we have analyzed correlations between pairs of partons of different kind, finding that, in some cases, they are strongly suppressed at low longitudinal momenta, while for other distributions they can be sizeable. For example, the effect of gluon-gluon correlations can be as large as 20 %. We have shown that these behaviors can be understood in terms of a delicate interference of non-perturbative correlations, generated by the dynamics of the model, and perturbative ones, generated by the model independent evolution procedure. Our analysis shows that at LHC kinematics two-parton correlations can be relevant in DPS, and therefore we address the possibility to study them experimentally. |
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Address |
[Rinaldi, Matteo; Scopetta, Sergio] Univ Perugia, Dipartimento Fis & Geol, I-06123 Perugia, Italy, Email: matteo.rinaldi@pg.infn.it; |
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Springer |
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English |
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ISSN |
1029-8479 |
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Conference |
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Notes |
WOS:000386670400001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2847 |
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Permanent link to this record |
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Author |
LHCb Collaboration (Aaij, R. et al); Garcia Martin, L.M.; Martinez-Vidal, F.; Oyanguren, A.; Remon Alepuz, C.; Ruiz Valls, P.; Sanchez Mayordomo, C. |
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Title |
Measurement of forward W -> e nu production in pp collisions at root s=8 TeV |
Type |
Journal Article |
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Year |
2016 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
10 |
Issue |
10 |
Pages |
030 - 29pp |
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Keywords |
Electroweak interaction; Hadron-Hadron scattering (experiments); QCD |
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Abstract |
A measurement of the cross-section for W -> e nu production in pp collisions is presented using data corresponding to an integrated luminosity of 2 fb(-1) collected by the LHCb experiment at a centre-of-mass energy of root s = 8 TeV. The electrons are required to have more than 20 GeV of transverse momentum and to lie between 2.00 and 4.25 in pseudorapidity. The inclusive W production cross-sections, where the W decays to e nu, are measured to be W-sigma(+)-> e(+)nu(e)= 1124.4 +/- 2.1 +/- 21.5 +/- 11.2 +/- 13.0 pb, W-sigma(-)-> e(-)(nu) over bar (e) = 809.0 +/- 1.9 +/- 18.1 +/- 7.0 +/- 9.4 pb, where the first uncertainties are statistical, the second are systematic, the third are due to the knowledge of the LHC beam energy and the fourth are due to the luminosity determination. Differential cross-sections as a function of the electron pseudorapidity are measured. The W+/W- cross-section ratio and production charge asymmetry are also reported. Results are compared with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics. Finally, in a precise test of lepton universality, the ratio of W boson branching fractions is determined to be B(W -> e nu)/B(W -> μnu) = 1.020 +/- 0.002 +/- 0.019, where the first uncertainty is statistical and the second is systematic. |
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Address |
[Bediaga, I.; Ferreira Rodrigues, F.; Gomes, A.; Massafferri, A.; dos Reis, A. C.; Rodrigues, A. B.; Vieira, D.] CBPF, Rio De Janeiro, Brazil, Email: marek.sirendi@cern.ch |
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Springer |
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English |
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1029-8479 |
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Expedition |
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Conference |
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Notes |
WOS:000386669800001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2848 |
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Permanent link to this record |
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Author |
Sborlini, G.F.R.; Driencourt-Mangin, F.; Rodrigo, G. |
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Title |
Four-dimensional unsubtraction with massive particles |
Type |
Journal Article |
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Year |
2016 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
10 |
Issue |
10 |
Pages |
162 - 34pp |
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Keywords |
NLO Computations |
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Abstract |
We extend the four-dimensional unsubtraction method, which is based on the loop-tree duality (LTD), to deal with processes involving heavy particles. The method allows to perform the summation over degenerate IR configurations directly at integrand level in such a way that NLO corrections can be implemented directly in four space-time dimensions. We define a general momentum mapping between the real and virtual kinematics that accounts properly for the quasi-collinear configurations, and leads to an smooth massless limit. We illustrate the method first with a scalar toy example, and then analyse the case of the decay of a scalar or vector boson into a pair of massive quarks. The results presented in this paper are suitable for the application of the method to any multipartonic process. |
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Address |
[Sborlini, German F. R.; Driencourt-Mangin, Felix; Rodrigo, German] Univ Valencia, CSIC, Inst Fis Corpuscular, Parc Cient, E-46980 Valencia, Spain, Email: german.sborlini@ific.uv.es; |
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Publisher |
Springer |
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English |
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1029-8479 |
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Conference |
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Notes |
WOS:000387374000001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
2853 |
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Permanent link to this record |
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Author |
Herrero-Garcia, J.; Rius, N.; Santamaria, A. |
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Title |
Higgs lepton flavour violation: UV completions and connection to neutrino masses |
Type |
Journal Article |
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Year |
2016 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
11 |
Issue |
11 |
Pages |
084 - 45pp |
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Keywords |
Beyond Standard Model; Higgs Physics; Neutrino Physics |
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Abstract |
We study lepton violating Higgs (HLFV) decays, first from the effective field theory (EFT) point of view, and then analysing the different high-energy realizations of the operators of the EFT, highlighting the most promising models. We argue why two Higgs doublet models can have a BR(h -> tau mu) similar to 0:01, and why this rate is suppressed in all other realizations including vector-like leptons. We further discuss HLFV in the context of neutrino mass models: in most cases it is generated at one loop giving always BR (h -> tau mu) < 10(-4) and typically much less, which is beyond experimental reach. However, both the Zee model and extended left-right symmetric models contain extra SU(2) doublets coupled to leptons and could in principle account for the observed excess, with interesting connections between HLFV and neutrino parameters. |
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Address |
[Herrero-Garcia, Juan] KTH Royal Inst Technol, AlbaNova Univ Ctr, Sch Engn Sci, Dept Theoret Phys, S-10691 Stockholm, Sweden, Email: juhg@kth.se; |
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Springer |
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English |
Summary Language |
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Series Volume |
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Series Issue |
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ISSN |
1029-8479 |
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Conference |
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Notes |
WOS:000387843300004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2862 |
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Permanent link to this record |
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Author |
de Florian, D.; Sborlini, G.F.R.; Rodrigo, G. |
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Title |
Two-loop QED corrections to the Altarelli-Parisi splitting functions |
Type |
Journal Article |
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Year |
2016 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
10 |
Issue |
10 |
Pages |
056 - 16pp |
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Keywords |
NLO Computations; QCD Phenomenology |
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Abstract |
We compute the two-loop QED corrections to the Altarelli-Parisi (AP) splitting functions by using a deconstructive algorithmic Abelianization of the well-known NLO QCD corrections. We present explicit results for the full set of splitting kernels in a basis that includes the leptonic distribution functions that, starting from this order in the QED coupling, couple to the partonic densities. Finally, we perform a phenomenological analysis of the impact of these corrections in the splitting functions. |
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Address |
[de Florian, Daniel] UNSAM, ICAS, Campus Miguelete,25 Mayo & Francia, RA-1650 Buenos Aires, DF, Argentina, Email: deflo@unsam.edu.ar; |
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Thesis |
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Publisher |
Springer |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1029-8479 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000386669900007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2863 |
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Permanent link to this record |