Energy dependence of the proton geometry in exclusive vector meson production

Kumar, Arjun; Toll, T.

doi:10.1103/physrevd.105.114011

Cited by 7 publications

(5 citation statements)

References 41 publications

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“…Note that STARlight does not make predictions for dissociative photoproduction. Other more recent predictions for the energy dependence of the proton geometry fluctuations have also been reported [56]. The FoCal data are uniquely positioned to probe the fluctuations of the proton target configurations for gluonic saturated matter.…”

Section: Physics Measurements In P-pb Upcs With Focalmentioning

confidence: 78%

Vector meson photoproduction in UPCs with FoCal

Bylinkin

Nystrand

∋Takaki

2023

J. Phys. G: Nucl. Part. Phys.

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We discuss the physics prospects of photon-induced measurements using the high-granularity FoCal detector to be installed at the ALICE experiment, covering the pseudorapidity interval 3.4 ≤ η ≤ 5.8. This new detector, scheduled to be in operation from Run 4, will explore the small Bjorken-x physics region in an unprecedented way. In this region the gluon saturation phenomenon is expected to be dominant. Combined with the rest of the ALICE subdetectors, including the zero degree calorimenters, FoCal will serve to reconstruct in a model-independent way the measured photoproduction cross sections for vectors mesons in a wide range of photon-target energies, down to x values of about 7 × 10-6 and 2 × 10-6 in ultra-peripheral photon–proton and photon–lead collisions, respectively.

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Section: Physics Measurements In P-pb Upcs With Focalmentioning

confidence: 78%

Vector meson photoproduction in UPCs with FoCal

Bylinkin

Nystrand

∋Takaki

2023

J. Phys. G: Nucl. Part. Phys.

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“…Also, our model does not have saturation scale (Q s ) fluctuations as IP-Glasma and the model in Ref. [27] do. Implementing this in our framework would require us to let the saturation scale of each hot spot fluctuate independently.…”

Section: Introductionmentioning

confidence: 80%

“…We also did not implement some physical ingredients that have been used in previous works using hot spots. These include: Q s fluctuations [12,[24][25][26][27], repulsion between hot spots [9,28] and hot spots within hot spots [29]. Another interesting addition to our model could be the inclusion of x-dependence through x-dependent hot spot size and number as in Ref.…”

Section: Discussionmentioning

confidence: 99%

“…Another interesting addition to our model could be the inclusion of x-dependence through x-dependent hot spot size and number as in Ref. [27]. evolution is probably due to the color fluctuation contribution increasing the difficulty of the numerical integration, as at short range its relative contribution to the two-point function is still of the order of ∼ 10%.…”

Section: Discussionmentioning

confidence: 99%

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Evolution of eccentricities induced by geometrical and quantum fluctuations in proton-nucleus collisions

Demirci¹,

Guerrero-Rodríguez²

2023

Preprint

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We compute the azimuthal eccentricities arising from initial stage fluctuations in high energy proton-nucleus collisions at proper times τ ≥ 0 + . We consider two sources of fluctuations, namely the geometrical structure of the proton and the fluctuation of color fields carried by both proton and nucleus. Describing these effects with Gaussian models allows us to analytically calculate the one-and two-point correlators of energy density, from which the eccentricities are obtained. We compute the proper time evolution of these quantities by approximating the Glasma dynamics in terms of linearized Yang-Mills equations, which we solve by assuming free field propagation and adopting the dilute-dense limit.

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“…Studies of the dependence of number of hotspots on momentum fraction x suggest that either the number of hotspots, or their widths will increase with smaller x (see [43] for our recent detailed investigation of these effects). This would manifest in the W γ p dependence of the cross section.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Investigating the structure of gluon fluctuations in the proton with incoherent diffraction at HERA

Kumar

Toll

2022

Eur. Phys. J. C

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Impact parameter dependent dipole models are ideal tools for investigating the spatial structure of the proton. We investigate the incoherent ep cross section in exclusive $$J/\psi $$ J / ψ photoproduction as measured by HERA, and find that as |t| increases, the models need several levels of substructure of gluon density fluctuations in order to describe the measured data well. In lieu of a perturbative description, we add this substructure by hand. This substructure is modelled as hotspots within hotspots. This enables us to describe measurements for $$|t|> 1$$ | t | > 1 GeV$$^2$$ 2 , which is necessary for describing any observable which integrate over the t-spectrum, such as the rapidity or $$W_{\gamma p}$$ W γ p . We find that three levels of proton substructure are adequate for a good description of all available ep data up to $$|t|=30$$ | t | = 30 GeV$$^2$$ 2 . We note that the gluonic density fluctuation structure follows a scaling behaviour, such that the logarithms of the number of hotspots and their size fall on a line, effectively reducing the available parameter space of the model. Our findings systematically constrains and provides a benchmark for the development of a perturbative model of spatial gluon fluctuations in nucleons.

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Energy dependence of the proton geometry in exclusive vector meson production

Cited by 7 publications

References 41 publications

Vector meson photoproduction in UPCs with FoCal

Vector meson photoproduction in UPCs with FoCal

Evolution of eccentricities induced by geometrical and quantum fluctuations in proton-nucleus collisions

Investigating the structure of gluon fluctuations in the proton with incoherent diffraction at HERA

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