References of "Physics Letters B"
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See detailIs dark matter made of mirror matter? Evidence from cosmological data
Ciarcelluti, Paolo; Wallemacq, Quentin ULg

in Physics Letters B (2014), 729

We present new fast numerical simulations of cosmic microwave background and large scale structure in the case in which the cosmological dark matter is made entirely or partly of mirror matter. We ... [more ▼]

We present new fast numerical simulations of cosmic microwave background and large scale structure in the case in which the cosmological dark matter is made entirely or partly of mirror matter. We consider scalar adiabatic primordial perturbations at linear scales in a flat Universe. The speed of the simulations allows us for the first time to use Markov Chain Monte Carlo analyses to constrain the mirror parameters. A Universe with pure mirror matter can fit very well the observations, equivalently to the case of an admixture with cold dark matter. In both cases, the analyses show a clear indication of the presence of a consistent amount of mirror dark matter, 0.05 < Ω_{mirror} h^2 < 0.12. [less ▲]

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See detailOn the observability of the quark orbital angular momentum distribution
Courtoy, Aurore ULg; Goldstein, Gary R.; Hernandez, J. Osvaldo Gonzalez et al

in Physics Letters B (2014), 731(0), 141-147

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See detailQCD description of charmonium plus light meson production in p̄-N annihilation
Pire, Bernard; Semenov-Tyan-Shanskiy, Kirill ULg; Szymanowski, Lech

in Physics Letters B (2013), 724

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See detailExtraction of $\alpha_s$ from deep inelastic scattering at large $x$
Courtoy, Aurore ULg; Liuti, Simonetta

in Physics Letters B (2013), B726

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See detailWilson lines and orbital angular momentum
Lorce, Cédric ULg

in Physics Letters B (2013), B719

We present an explicit realization of the Chen et al. approach to the proton spin decomposition in terms of Wilson lines, generalizing the light-front gauge-invariant extensions discussed recently by ... [more ▼]

We present an explicit realization of the Chen et al. approach to the proton spin decomposition in terms of Wilson lines, generalizing the light-front gauge-invariant extensions discussed recently by Hatta. Particular attention is drawn to the residual gauge freedom by further separating the pure-gauge term into contour and residual terms. We show that the kinetic orbital angular momentum operator can be expressed in terms of the Wigner operator only when the momentum variable is integrated over. Finally, we confirm from twist-2 arguments that the advanced, retarded and antisymmetric light-front canonical orbital angular momenta are the same. [less ▲]

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See detailReassessing the importance of the colour-singlet contributions to direct $J/ + W$ production at the LHC and the Tevatron
Lansberg, Jean-Philippe ULg; Lorce, Cédric ULg

in Physics Letters B (2013), B726

We show that the colour-singlet contributions to the hadroproduction of $J/\Psi$ in association with a W boson are sizable, if not dominant over the colour-octet contributions. They are of two kinds, $sg ... [more ▼]

We show that the colour-singlet contributions to the hadroproduction of $J/\Psi$ in association with a W boson are sizable, if not dominant over the colour-octet contributions. They are of two kinds, $sg\toJ/\Psi+c+W$ at $\alpha^3s\alpja$ and $q\overline q' \to\gamma^\star /Z ^\star W\to J/\Psi W$ at order $\alpha^3$. These have not been considered in the literature until now. Our conclusion is that the hadroproduction of a $J/\Psi$ in association with a W boson cannot be claimed as a clean probe of the colour-octet mechanism. The rate are small even at the LHC and it will be very delicate to disentangle the colour-octet contributions from the sizable colour-singlet ones and from the possibly large double-parton-scattering contributions. During this analysis, we have also noted that, for reactions such as the production of a $J/\Psi$ by light quark–antiquark fusion, the colour-singlet contribution via an off-shell photon is of the order of the expectation from the colour-octet contribution via an off-shell gluon. This is relevant for inclusive production at low energies close to the threshold. Such an observation also likely extends to other processes naturally involving light-quark annihilation. [less ▲]

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See detailPretzelosity TMD and Quark Orbital Angular Momentum
Lorce, Cédric ULg; Pasquini, B.

in Physics Letters B (2012), B710

We study the connection between the quark orbital angular momentum and the pretzelosity transverse momentum dependent parton distribution function. We discuss the origin of this relation in quark models ... [more ▼]

We study the connection between the quark orbital angular momentum and the pretzelosity transverse momentum dependent parton distribution function. We discuss the origin of this relation in quark models, identifying as key ingredient for its validity the assumption of spherical symmetry for the nucleon in its rest frame. Finally we show that the individual quark contributions to the orbital angular momentum obtained from this relation cannot be interpreted as the intrinsic contributions, but include the contribution from the transverse centre of momentum which cancels out only in the total orbital angular momentum. [less ▲]

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See detailHiggs Central Exclusive Production
Cudell, Jean-René ULg; Dechambre, Alice; Henandez, Oscar F.

in Physics Letters B (2012), 706

We tune the calculation of central exclusive Higgs production to the recent CDF central exclusive dijet data, and predict the cross section for the exclusive production of Higgs boson at the LHC. It is ... [more ▼]

We tune the calculation of central exclusive Higgs production to the recent CDF central exclusive dijet data, and predict the cross section for the exclusive production of Higgs boson at the LHC. It is always below 1 fb, and below 0.3 fb after experimental cuts. [less ▲]

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See detailFrustrated symmetries in multi-Higgs-doublet models
Ivanov, Igor ULg; Keus, Venus ULg

in Physics Letters B (2011), 695(5), 459-462

Within multi-Higgs-doublet models, one can impose symmetries on the Higgs potential, either discrete or continuous, that mix several doublets. In two-Higgs-doublet model any such symmetry can be conserved ... [more ▼]

Within multi-Higgs-doublet models, one can impose symmetries on the Higgs potential, either discrete or continuous, that mix several doublets. In two-Higgs-doublet model any such symmetry can be conserved or spontaneously violated after the electroweak symmetry breaking (EWSB), depending on the coefficients of the potential. With more than two doublets, there exist symmetries which are always spontaneously violated after EWSB. We discuss the origin of this phenomenon and show its similarity to frustration in condensed matter physics. [less ▲]

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See detailAssociated production of one particle and a Drell-Yan pair in hadronic collisions
Ceccopieri, Federico ULg

in Physics Letters B (2011), 703(4), 491-497

We propose a collinear factorization formula for the associated production of one particle and a Drell-Yan pair in hadronic collisions. It is shown that additional collinear singularities appearing in the ... [more ▼]

We propose a collinear factorization formula for the associated production of one particle and a Drell-Yan pair in hadronic collisions. It is shown that additional collinear singularities appearing in the next-to-leading order calculations that cannot be factorized into parton and fragmentation functions are systematically renormalized by introducing fracture functions. Next-to-leading order coefficient functions for cross-sections double differential in the fractional energy of the identified hadron and lepton pair invariant mass are presented. [less ▲]

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See detailEnhancement effects in exclusive ππ and ρπ production in γ* γ scattering
Courtoy, Aurore ULg; Noguera, S.

in Physics Letters B (2009), 675(1), 38-42

The exclusive ππ and ρπ production in hard γ* γ scattering in the forward kinematical region where the virtual photon is highly off-shell is studied using the γ → π- Transition Distribution Amplitudes ... [more ▼]

The exclusive ππ and ρπ production in hard γ* γ scattering in the forward kinematical region where the virtual photon is highly off-shell is studied using the γ → π- Transition Distribution Amplitudes obtained in realistic models for the pion. For ρπ production we confirm the previous estimates before QCD evolution. Nevertheless, once evolution is taken into account this cross section grows one order of magnitude. In the case of ππ production we have evaluated the cross section including the pion pole contribution. We observe that this contribution is responsible for an enhancement of two orders of magnitude with respect to the cross section evaluated without the pion pole term. © 2009 Elsevier B.V. All rights reserved. [less ▲]

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See detailVariations on leptogenesis
Aristizabal Sierra, Diego ULg; Losada, Marta; Enrico, Nardi

in Physics Letters B (2008), 659

We study variations of the standard leptogenesis scenario that can arise if an additional mass scale related to the breaking of some new symmetry (as for example a flavor or the B–L symmetry) is present ... [more ▼]

We study variations of the standard leptogenesis scenario that can arise if an additional mass scale related to the breaking of some new symmetry (as for example a flavor or the B–L symmetry) is present below the mass MN1 of the lightest right-handed Majorana neutrino. Our scheme is inspired by U(1) models of flavor à la Froggatt–Nielsen, and involves new vectorlike heavy fields F. We show that depending on the specific hierarchy between MN1 and the mass scale of the fields F, qualitatively different realizations of leptogenesis can emerge. We compute the CP asymmetries in N1 decays in all the relevant cases, and we conclude that in most situations leptogenesis could be viable at scales much lower than in the standard scenario. [less ▲]

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See detailUnitarisation and black-disk limit at the LHC in the presence of a hard pomeron
Cudell, Jean-René ULg; Selyugin, Oleg Viktorovich

in Physics Letters B (2008), 662(5), 417-423

Recent models of soft diffraction include a hard pomeron pole besides the usual soft term. Such models violate the black-disk limit around Tevatron energies, so that they need to be supplemented by a ... [more ▼]

Recent models of soft diffraction include a hard pomeron pole besides the usual soft term. Such models violate the black-disk limit around Tevatron energies, so that they need to be supplemented by a unitarisation scheme. Two standard schemes are considered in this Letter, and we show that they lead to an uncertainty at the LHC much larger than previously estimated. We also examine the signature of unitarisation on various small-t observables, the slope in t of the elastic cross section, or the ratio of the real to imaginary parts of the scattering amplitude, and show that the existence of a unitarised hard pomeron in soft scattering may be confirmed by LHC data. (C) 2008 Elsevier B.V. All rights reserved. [less ▲]

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See detailNew contributions to heavy-quarkonium production
Lansberg, Jean-Philippe ULg; Cudell, Jean-René ULg; Kalinovsky, Y. L.

in Physics Letters B (2006), 633(2-3), 301-308

We reconsider quarkonium production in a field-theoretical setting and we show that the lowest-order mechanism for heavy-quarkonium production receives in general contributions from two different cuts ... [more ▼]

We reconsider quarkonium production in a field-theoretical setting and we show that the lowest-order mechanism for heavy-quarkonium production receives in general contributions from two different cuts. The first one corresponds to the usual colour-singlet mechanism. The second one has not been considered so far. We treat it in a gauge-invariant manner, and introduce new 4-point vertices, suggestive of the colour-octet mechanism. These new objects enable us to go beyond the static approximation. We show that the contribution of the new cut can be as large as the usual colour-singlet mechanism at high P-T for J/psi. In the psi' case, theoretical uncertainties are shown to be large and agreement with data is possible. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailTwo-Higgs-doublet model from the group-theoretic perspective
Ivanov, Igor ULg

in Physics Letters B (2006), 632(2-3), 360-365

In the two-Higgs-doublet model, different Higgs doublets can be viewed as components of a generic “hyperspinor”. We decompose the Higgs potential of this model into irreducible representations of the SU(2 ... [more ▼]

In the two-Higgs-doublet model, different Higgs doublets can be viewed as components of a generic “hyperspinor”. We decompose the Higgs potential of this model into irreducible representations of the SU(2) group of transformations of this hyperspinor. We discuss invariant combinations of Higgs potential parameters λi that arise in this decomposition and provide simple and concise sets of conditions for the hidden Z2-symmetry, Peccei–Quinn symmetry, and explicit CP-conservation in 2HDM. We show that some results obtained previously by brute-force calculations are reduced to simple linear algebraic statements in our approach. [less ▲]

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See detailExcited [70,l(+)] baryons in large N-c QCD
Matagne, Nicolas; Stancu, Floarea ULg

in Physics Letters B (2005), 631(1-2), 7-15

The masses of the positive parity [70, 0(+)] and [70, 2(+)] non-strange baryons are calculated in large N-c QCD by considering the most dominant operators in an 1/N-c expansion. The approach is based on ... [more ▼]

The masses of the positive parity [70, 0(+)] and [70, 2(+)] non-strange baryons are calculated in large N-c QCD by considering the most dominant operators in an 1/N-c expansion. The approach is based on the introduction of an excited core, obtained after the last particle (an excited quark) has been removed. Configuration mixing is neglected, for simplicity. Although being a sub-leading 1/Nc order, we find that the spin-spin interaction plays a dominant role in describing the data. The role of No operators is also pointed out. We show how the contribution of the linear term in Nc, of the spin-spin and of the spin-orbit terms vary with the excitation energy. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailProduction of orbitally excited vector mesons in diffractive DIS
Caporale, Francesco; Ivanov, Igor ULg

in Physics Letters B (2005), 622(1-2), 55-62

Within the kt-factorization framework, we study diffractive production of orbitally excited vector mesons and compare it with the production of radial excitations, focusing on the ρ(1450)/ρ(1700) case. At ... [more ▼]

Within the kt-factorization framework, we study diffractive production of orbitally excited vector mesons and compare it with the production of radial excitations, focusing on the ρ(1450)/ρ(1700) case. At small Q2, orbital excitation of light quarkonia is found to dominate over radial excitations in diffractive production. We predict strong suppression of the production of orbital excitations by longitudinal photons, which leads to very small σL/σT ratio. At small Q2, the s-channel helicity violating transitions contribute not, vert, similar10–15% of the transverse cross section and not, vert, similar50% of the longitudinal cross section. We also study mixing between radial and orbital excitations and determine strategies towards clarification of S-wave/D-wave assignment to ρ(1450) and ρ(1700) mesons. The results are compared with the experimental data available, and predictions for future experiments are given. [less ▲]

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See detailDynamical study of the pentaquark antidecuplet
Stancu, Floarea ULg

in Physics Letters B (2004), 595

Dynamical calculations are performed for all isomultiplets of the flavour antidecuplet to which the newly discovered pentaquark Theta(+) belongs. The framework is a constituent quark model where the short ... [more ▼]

Dynamical calculations are performed for all isomultiplets of the flavour antidecuplet to which the newly discovered pentaquark Theta(+) belongs. The framework is a constituent quark model where the short-range interaction has a flavour-spin structure. In this model the lowest pentaquarks have positive parity. Each antidecuplet member is described by a variational solution with the Pauli principle properly taken into account. By fitting the mass of Theta(+) of minimal content uudd, the mass of Xi(--), of minimal content ddss (u) over bar, is predicted at approximately 1960 MeV. The influence of the octet-antidecuplet mixing on the masses of the Y = I and 0 pentaquarks is considered within the same model and the role of the hyperfine interaction in this mixing is pointed out. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailA model for the off-forward structure functions of the pion
Bissey, F.; Cudell, Jean-René ULg; Cugnon, Joseph ULg et al

in Physics Letters B (2004), 587(3-4), 189-200

We extend our model for the pion, which we used previously to calculate its diagonal structure function, to the off-forward case. The imaginary part of the off-forward y*pi -->. gamma*pi scattering ... [more ▼]

We extend our model for the pion, which we used previously to calculate its diagonal structure function, to the off-forward case. The imaginary part of the off-forward y*pi -->. gamma*pi scattering amplitude is evaluated in the chiral limit (m(pi) = 0) and related to the twist-two and twist-three generalised parton distributions H, H-3, (H) over tilde (3). Non-perturbative effects, linked to the size of the pion and still preserving gauge invariance, are included. Remarkable new relations between H, H3 and (H) over tilde (3) are obtained and discussed. (C) 2004 Published by Elsevier B.V. [less ▲]

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See detailThe hard pomeron in soft data
Cudell, Jean-René ULg; Martynov, Evgenij; Selyugin, Oleg Viktorovich et al

in Physics Letters B (2004), 587(1-2), 78-86

We show that the data for the total cross section and for the real part of the elastic amplitude indicate the presence of a hard pomeron in pip and Kp elastic scattering at t = 0, compatible with that ... [more ▼]

We show that the data for the total cross section and for the real part of the elastic amplitude indicate the presence of a hard pomeron in pip and Kp elastic scattering at t = 0, compatible with that observed in deep inelastic scattering. We show that such a hard pomeron is also compatible with pp and pp data, provided one unitarises it at high energy. (C) 2004 Published by Elsevier B.V. [less ▲]

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