In order to understand more precisely the gluon saturation phenomenon at low x and the kinematical range in which it happens, higher order corrections need to be included. With that goal in mind, the NLO corrections to DIS structure functions in the dipole factorization and to various particle production processes at the LHC have been recently calculated, as well as the BK and JIMWLK...
Deep Inelastic Scattering (DIS) is the cleanest tool available to probe the content of a fast proton or nucleus. In the regime of low Bjorken x, one enters in the nonlinear regime of gluon saturation where the gluons are better described within the framework of Color Glass Condensate (CGC) and the dipole factorization. This framework allows to resum coherent multiple scattering on the target,...
Pomeron was introduced in the framework of the phenomenological Regge theory.
It governs the high-energy asymptotics of various hadronic processes and the small-$x$ behavior of $F_1$ in particular.
The best-known contribution to the QCD Pomeron comes from the BFKL equation which
sums Leading Logarithmic (LL) contributions i.e. the
single-logarithmic (SL) contributions $\sim (\alpha_s \ln...
The NLO Balitsky-Kovchegov (BK) equation describing the high-energy evolution of the scattering between a dilute projectile and a dense target suffers from instabilities unless it is supplemented by a proper resummation of large (anti-)collinear logarithms. Earlier studies showed that if one expresses the evolution in terms of the rapidity of the dilute projectile, the dominant anti-collinear...
In the Color Glass Condensate framework the profile of the target is modelled by the saturation scale, $Q_s(\vec b)$. In the literature it is commonly assumed that the length scale of the fluctuations of the saturation scale, $l_{fluc.}$, is large. One implication of this approximation is that the gluon dipole cannot couple to gradients of the saturation scale. Using the McLerran-Venugopalan...
A new fit of diffractive parton distribution functions (DPDFs) to the HERA inclusive and jet data in diffractive deep-inelastic scattering (DDIS) at next-to-next-to-leading order accuracy (NNLO) is presented. The inclusion of the most comprehensive dijet cross section data, together with their NNLO predictions, provide enhanced constraints to the gluon component of the DPDF, which is of...
Inclusive single diffractive dissociation (pp->pX) is studied using data collected by the ATLAS experiment at the LHC. The intact proton is reconstructed and measured in the ALFA forward spectrometer, while charged particles from the dissociative system (X) are reconstructed and measured using the ATLAS inner tracking detector and calorimeters. Differential cross sections are presented as a...
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The TOTEM experiment at the LHC has measured proton-proton elastic scattering in dedicated runs at √s = 2.76, 7, 8 and 13 TeV centre-of-mass
LHC energies. The proton-proton total cross-section has been derived for each energy using a luminosity independent method. TOTEM has
excluded a purely exponential differential cross-section for elastic proton-proton scattering with significance greater...
Recent results of the TOTEM collaboration [1] suggest that the odderon exchange can be responsible for a disagreement of theoretical calculations and the TOTEM data [2] for elastic $pp$ scattering. It is premature to draw conclusions. Here we present our recent studies for three different processes in $pp$ collisions where the odderon may show up. We apply recently proposed tensor-pomeron and...
We discuss Dyson-Schwinger hierarchy of the equations for the correlators of reggeized gluon fields in the framework of Lipatov's
high energy QCD effective action formalism.
The non-linear corrections to the two-field correlators are presented and correspondence between the correlators of reggeized gluon fields and Wilson line
operators of longitudinal gluon fields is established,
the...
The gauge-invariant EFT for Multi-Regge processes in QCD [1,2] has bee introduced to facilitate the computation of NLO corrections in the BFKL approach. The main difficulty in this approach is the appearance of rapidity divergences (RDs) in loop integrals, which are not regularized by dimensional regularization and require separate regularization, see Ref. [3] for more details. We will discuss...
We investigate the high energy proton-proton scattering in the framework of holographic QCD, which is an effective approach to QCD constructed based on the AdS/CFT correspondence. In our model setup, the involved nonperturbative partonic dynamics is described by the Pomeron exchange, which is realized applying the Reggeized spin 2 particle propagator together with the proton gravitational form...
We present new quantitative predictions for the distribution of the total invariant mass produced diffractively in dipole-nucleus scattering at large relative rapidity. We show that the shape of this distribution is intimately related to the properties of the fluctuations in the small-x partonic evolution. This observable can potentially be measured at a future electron-ion collider.
*Based on...
We present results for the diffractive dijet production cross section in e+p collisions within the color glass condensate framework to leading logarithmic accuracy. The framework includes a spatially dependent McLerran-Venugopalan initial configuration at relatively large $x$, combined with explicit numerical solution of the JIMWLK equations. We focus in particular on the dependence of the...
The forward Drell-Yan (DY) lepton pair production together with a backward jet is proposed as a new way to study the BFKL effects due to a large rapidity gap between the two systems. Predictions for quantities to be measured are computed using the leading order DY impact factors and the BFKL kernel with a consistency condition which takes into account an important part of the next-to-leading...
The inclusive photoproduction of two heavy quark–antiquark pairs, separated by a large rapidity interval, is proposed as a new channel for the manifestation of the Balitsky–Fadin–Kuraev–Lipatov (BFKL) dynamics. The extension to the hadroproduction case will also be discussed.
Unequal rapidity correlations can be studied within the stochastic Langevin picture of JIMWLK evolution in the Colour Glass Condensate effective field theory. By evolving the classical field in the direct and complex conjugate amplitudes, the Langevin formalism can be used to study two-particle production at large rapidity separations. The evolution between the rapidities of the two produced...
We analyze contributions to diffractive photoproduction and inclusive hadroproduction of J/psi with large transverse momentum coming from cut BFKL Pomeron loops in the corresponding cross sections. In this framework the diffractive photoproduction is described by the diffractive cut of two Pomeron exchange. For the hadroproduction we consider a gluon to J/psi transition mediated by an exchange...
We discuss the $k_{T}$-factorization approach for $c \bar c$ production in the context of the color evaporation model for $J/\psi$ meson production. We use a new approach to color evaporation model (CEM) for quarkonium production. The production of $c\bar c$ pairs is performed within $k_T$-factorization approach using different unintegrated gluon distribution functions (UGDF) from the...
Exclusive photoproduction of $\rho(770)$ vector mesons is studied using the H1 detector at HERA. A sample of about 700000 decays $\rho\to\pi^{+}\pi^{-}$ was collected in the years 2006-2007, using the H1 fast track trigger. It corresponds to an integrated luminosity of $1.3$ pb$^{−1}$. The sample is used to study cross-sections as a function of the invariant mass $m_{\pi\pi}$ of the decay...
The exclusive photoproduction reaction $\gamma p \to \psi(2S) p$ has been studied with the ZEUS detector in $ep$ collisions at HERA using an integrated luminosity of 350 pb$^{-1}$, in the kinematic range $30 < W < 180$ GeV, $Q^2 < 1$ GeV$^2$, $|t| < 5$ GeV$^2$, where $W$ is the photon-proton centre-of-mass energy, $Q^2$ - the photon virtuality and $t$ – four-momentum transfer at the proton...
A significant sample of $p^{\uparrow}p\to p\pi^{0} X$ events have been observed at STAR in $\sqrt{s}=200$ GeV
transversely polarized $pp$ collisions, where an isolated $\pi^0$ is detected in the forward
pseudorapidity range $2.65<\eta<3.9$ along with the forward-going proton $p$, which scatters with a
near-beam forward pseudorapidity into Roman Pot detectors. The sum of the $\pi^{0}$ and the...
Ultra-peripheral nucleus-nucleus collisions (UPC) are mediated by strong
electromagnetic fields, offering the opportunity to study photon-nucleus pro-
cesses at RHIC. Coherent J/ψ photoproduction is of particular interest for its
sensitivity to nuclear gluon distribution. The J/ψ mesons are heavy enough to
be described by perturbative Quantum Chromodynamics (pQCD), where coher-
ent cross...
The strong electromagnetic fields of Pb nuclei, accelerated at the LHC, can be used to measure photon-induced interactions in a new kinematic regime. Photon-induced processes are usually studied in ultra-peripheral Pb-Pb collisions where hadronic interactions are strongly suppressed. Coherent charmonium photoproduction is of particular interest since it is sensitive to poorly known gluon...
The forward acceptance of LHCb, 2.0 < y < 5.0, provides complementary reach to the general purpose detectors at the LHC for the study of Soft QCD processes. In addition, the installation of a series of scintillating pad detectors (Herschel), bracketing the LHCb detector along the beamline, for Run 2 of the LHC, with dedicated triggers, has significantly enhanced LHCb's sensitivity to central...
Merged abstract
We argue that ultraperipheral collisions at the LHC allow to study effects color fluctuations (CF) of the strength of interaction of photon in large and small size configurations. We make predictions for the distribution over the number of wounded nucleons ν in the inelastic photon-nucleus scattering and in events with charm production. We show that CFs lead to a dramatic enhancement of this...
I will discuss how the theoretical stability of exclusive HVM photoproduction has been improved through a systematic taming of the known MSbar coefficient functions by accounting for a not so power suppressed correction encoded within a ‘Q0’ cut. The phenomenological implications of this will be emphasised allowing for, ultimately, the inclusion of the exclusive data into a global fitter...
Merged abstract
Photon-photon fusion is a rare process at hadron and ion colliders. It is particularly interesting as a remarkably clean interaction with little (if any) remnant activity from the interacting particles. In this talk we present the status of photon-photon fusion measurements at the ATLAS detector, focussing on two types of analyses. In the first type of analysis, the ATLAS inner tracking...
We analyze in detail the LHC prospects for charged electroweakino searches, decaying to leptons, in compressed supersymmetry scenarios, via exclusive photon-initiated pair production. This provides a potentially increased sensitivity in comparison to inclusive channels, where the background is often overwhelming. We pay particular attention to the challenges that such searches would face in...
The tensor-pomeron model is applied to low-x deep-inelastic lepton-nucleon scattering and photoproduction. We consider c. m. energies in the range 6 - 318 GeV and $Q^2 < 50$ GeV$^2$. In addition to the soft tensor pomeron, which has proven quite successful for the description of soft hadronic high-energy reactions, we include a hard tensor pomeron. We also include $f_2$-reggeon exchange which...
Semi-hard processes serve as a special testing ground for calculations of high-energy scatterings in perturbative QCD. In this kinematic limit, the enhanced effect of energy logarithms calls for an all-order resummation procedure. The most natural language to resum these large logarithms, both in the leading and the next-to-leading approximation, is elegantly embodied by the BFKL approach....
Using the formalism of the light-cone wave function in perturbative QCD together with the hybrid factorization, we compute the cross-section for three (and two) particle production at forward rapidities in proton-nucleus collisions. We focus on the quark channel, in which the three produced partons -- a quark accompanied by a gluon pair, or two quarks plus one antiquark -- are all generated...
We consider the non-eikonal corrections to particle production in the Color Glass Condensate originating from relaxing the shockwave approximation for the target which takes into account its finite longitudinal thickness. We derive a modified expression of the Lipatov vertex that accounts for these corrections. This expression is employed to compute single, double and triple gluon production...
In quantum mechanics, Einstein, Podolsky, and Rosen (EPR) formulated an apparent paradox of quantum theory in 1935. They considered two quantum mechanical systems were first brought to interaction, then later separated to large distance. A measurement of a physical observable in one system would have an immediate effect on the conjugate observable in the other system, even when they are...
