Positivity bounds on gluon TMDs for hadrons of spin ≤\le 1

We consider the transverse momentum dependent gluon distribution functions (called gluon TMDs) by studying the light-front gluon-gluon correlator, extending the results for unpolarized and vector polarized targets to also include tensor polarized targets -- the latter type of polarization is relevant for targets of spin $\ge1$. The light-front correlator includes process-dependent gauge links to guarantee color gauge invariance. As from the experimental side the gluon TMDs are largely unknown, we present positivity bounds for combinations of leading-twist gluon distributions that may be used to estimate their maximal contribution to observables. Since the gluonic content of hadrons is particularly relevant in the small-$x$ kinematic region, we also study these bounds in the small-$x$ limit for the dipole-type gauge link structure using matrix elements of a single Wilson loop.Comment: 10 page

Theoretical restrictions on the parameters of the indirect addilog system revisited

The correct parameter restrictions- less restrictive than commonly thought-of the indirect addilog system (IAS) are derived. Under correct restrictions, the IAS is superior to the linear expenditure system in computable general equilibrium models with data scarcity.CGE-modelling;indirect addilog system;parameter restriction

Directed flow from C-odd gluon correlations at small xx

It is shown that odd harmonic azimuthal correlations, including the directed flow $v_1$, in forward two-particle production in peripheral proton-nucleus ($pA$) collisions can arise simply from the radial nuclear profile of a large nucleus. This requires consideration of the C-odd part of the gluonic generalized transverse momentum dependent (GTMD) correlator of nucleons in the nucleus. The gluonic GTMD correlator is the Fourier transform of an off-forward hadronic matrix element containing gluonic field strength tensors that are connected by gauge links. It is parametrized in terms of various gluon GTMD distribution functions (GTMDs). We show (in a gauge invariant way) that for the relevant dipole-type gauge link structure in the small-$x$ limit the GTMD correlator reduces to a generalized Wilson loop correlator. The Wilson loop correlator is parametrized in terms of a single function, implying that in the region of small $x$ there is only one independent dipole-type GTMD, which can have a C-odd part. We show that the odderon Wigner distribution, which is related to this C-odd dipole GTMD by a Fourier transform, generates odd harmonics in the two-particle azimuthal correlations in peripheral $pA$ collisions. We calculate the first odd harmonic $v_1$ for forward production within the color glass condensate framework in the limit of a large number of colors. We find that nonzero odd harmonics are present without breaking the rotational symmetry of the nucleus, arising just from its inhomogeneity in the radial direction. Using a CGC model with a cubic action, we illustrate that percent level $v_1$ can arise from this C-odd mechanism. In contrast, we show that only even harmonics arise in diffractive dijet production in ultra-peripheral $pA$ collisions where this gluon dipole GTMD also appears.Comment: 23 pages, 3 figures. v2: References added; Added plot for A=63 in Fig.3 and a discussion on the A dependence. Version accepted for publication in JHE

Colour unwound - disentangling colours for azimuthal asymmetries in Drell-Yan scattering

It has been suggested that a colour-entanglement effect exists in the Drell-Yan cross section for the 'double T-odd' contributions at low transverse momentum $Q_T$, rendering the colour structure different from that predicted by the usual factorisation formula [1]. These T-odd contributions can come from the Boer-Mulders or Sivers transverse momentum dependent distribution functions. The different colour structure should be visible already at the lowest possible order that gives a contribution to the double Boer-Mulders (dBM) or double Sivers (dS) effect, that is at the level of two gluon exchanges. To discriminate between the different predictions, we compute the leading-power contribution to the low-$Q_T$ dBM cross section at the two-gluon exchange order in the context of a spectator model. The computation is performed using a method of regions analysis with Collins subtraction terms implemented. The results conform with the predictions of the factorisation formula. In the cancellation of the colour entanglement, diagrams containing the three-gluon vertex are essential. Furthermore, the Glauber region turns out to play an important role - in fact, it is possible to assign the full contribution to the dBM cross section at the given order to the region in which the two gluons have Glauber scaling. A similar disentanglement of colour is found for the dS effect.Comment: 36 pages, 11 figures; v2: typos corrected/ reference added, v3: minor corrections/ small explanations added/ references added, v4: very minor correction/ small explanations added/ references added (this version has been accepted for publication in SciPost

Theoretical restrictions on the parameters of the indirect addilog system revisited

The correct parameter restrictions- less restrictive than commonly thought-of the indirect addilog system (IAS) are derived. Under correct restrictions, the IAS is superior to the linear expenditure system in computable general equilibrium models with data scarcity

Cognitive processes mediate the effects of insomnia treatment:evidence from a randomized wait-list controlled trial

INTRODUCTION: Both guided online and individual face-to-face cognitive behavioral therapy for insomnia (CBT-I) are effective in improving insomnia symptoms and sleep efficiency. Little is known about the underlying mechanisms generating this effect. The present study tests the assumption that pre-sleep arousal, sleep-related worry and dysfunctional beliefs about sleep are mediators in the effect of cognitive behavioral treatment for insomnia. METHODS: A secondary analysis was performed on data previously collected from a randomized controlled trial (N = 90). In this trial, participants were randomized to either a face-to-face CBT-I condition, an internet-delivered CBT-I condition, or a wait-list group. This article reports on the efficacy of these interventions on pre-sleep arousal, sleep-related worry, and dysfunctional beliefs. Furthermore, we investigated whether these measures mediated the treatment effect on insomnia severity and sleep efficiency. RESULTS: Both treatment modalities were efficacious for these cognitive measures; however, face-to-face treatment showed superiority over the online treatment. All three cognitive measures mediated the effect on insomnia severity. Sleep-related worry and pre-sleep arousal mediated the effect on sleep efficiency, but dysfunctional beliefs did not. CONCLUSION: Overall, these results point toward the importance of cognitive processes in the treatment of insomnia, implying that psychological treatments for insomnia may best be guided by (also) targeting these cognitive processes