A Glimpse of Gluons through Deeply Virtual Compton Scattering on the Proton

The proton is composed of quarks and gluons, bound by the most elusive mechanism of strong interaction called confinement. In this work, the dynamics of quarks and gluons are investigated using deeply virtual Compton scattering (DVCS): produced by a multi-GeV electron, a highly virtual photon scatters off the proton which subsequently radiates a high energy photon. Similarly to holography, measuring not only the magnitude but also the phase of the DVCS amplitude allows to perform 3D images of the internal structure of the proton. The phase is made accessible through the quantum-mechanical interference of DVCS with the Bethe-Heitler (BH) process, in which the final photon is emitted by the electron rather than the proton. We report herein the first full determination of the BH-DVCS interference by exploiting the distinct energy dependences of the DVCS and BH amplitudes. In the high energy regime where the scattering process is expected to occur off a single quark in the proton, these accurate measurements show an intriguing sensitivity to gluons, the carriers of the strong interaction.

Similar Publications

A statistical combination of searches is presented for massive resonances decaying to WW, WZ, ZZ, WH, and ZH boson pairs in proton-proton collision data collected by the CMS experiment at the LHC. The data are taken at centre-of-mass energies of 8 and 13 TeV, corresponding to respective integrated luminosities of 19.7 and up to 2. Read More

We present an approach to the momentum-space resummation of global, recursive infrared and collinear safe observables featuring kinematic zeros away from the Sudakov limit. In the hadro-production of a generic colour singlet, we consider the family of inclusive observables which do not depend on the rapidity of the radiation, prime examples being the transverse momentum of the singlet, and $\phi^*$ in Drell-Yan pair production. We derive a resummation formula valid up to next-to-next-to-next-to-leading-logaritmic accuracy for the considered observables. Read More

Highlights of measurements of the properties of the top quark at the LHC are presented. The measurements probe a range of the properties of the top quark, including the structure of the $Wtb$ vertex, the top-Z coupling and the top-quark mass. The results are compared to Standard Model predictions and in some cases limits on physics beyond the Standard Model are also extracted in the context of effective field theory models. Read More

We present a fully-differential and high-precision calculation of top-quark pair-production and decay at the LHC, providing predictions for observables constructed from top-quark leptonic and $b$-flavoured jet final states. The calculation is implemented in a parton-level Monte Carlo and includes an approximation to the next-to-next-to leading order (NNLO) corrections to the production and, for the first time, the exact NNLO corrections to the decay subprocesses. The corrections beyond NLO are sizeable, and including them is crucial for an accurate description of the cross section constrained by experimental phase-space restrictions. Read More

We report the results of a first experimental search for lepton number violation by four units in the neutrinoless quadruple-$\beta$ decay of $^{150}$Nd using a total exposure of $0.19$ kg$\cdot$y recorded with the NEMO-3 detector at the Modane Underground Laboratory (LSM). We find no evidence of this decay and set lower limits on the half-life in the range $T_{1/2}>(1. Read More

In this paper we present a detailed comparison of the dijet production by photon -- photon, photon -- pomeron and pomeron -- pomeron interactions in ${\rm pp}$, ${\rm pA}$ and ${\rm AA}$ collisions at the LHC energy. The transverse momentum, pseudo -- rapidity and angular dependencies of the cross sections are calculated at LHC energy using the Forward Physics Monte Carlo (FPMC), which allows to obtain realistic predictions for the dijet production with two leading intact hadrons. We obtain that $\gamma \mathbb {P}$ channel is dominant at forward rapidities in ${\rm pp}$ collisions and in the full kinematical range in nuclear collisions of heavy nuclei. Read More

The precision measurement of the $d\sigma(e^+e^- \rightarrow \mu^+\mu^- \gamma)/d\sqrt{s}$ cross section with the photon emitted in the initial state with the KLOE detector has been used to measure the running of the QED coupling constant $\alpha(s)$ in the energy range 0.6 $< \sqrt{s} <$ 0.975 GeV in the time-like region. Read More

Identifying the flavour of neutral $B$ mesons production is one of the most important components needed in the study of time-dependent $CP$ violation. The harsh environment of the Large Hadron Collider makes it particularly hard to succeed in this task. We present an inclusive flavour-tagging algorithm as an upgrade of the algorithms currently used by the LHCb experiment. Read More

Possible manifestations of the isospin-breaking mixing of the $a^0_0(980)$ and $f_0(980)$ resonances are analyzed in the $D^0\to K^0_S \pi^+\pi^-$ and $D^0\to K^0_S\eta\pi^0$ decays. It is shown that the $a^0_0(980)-f_0(980)$ mixing has the most influence on the $\pi^+\pi^-$ mass spectrum in the decay $D^0\to K^0_S\pi^+\pi^-$. Owing to the $a^0_0(980)-f_0(980)$ mixing, the $f_0(980)$ peak in $D^0 \to K^0_Sf_0(980)\to K^0_S \pi^+\pi^-$ can experience distortions comparable with its size. Read More

In this document, the technical details of the JSNS$^2$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment are described. The search for sterile neutrinos is currently one of the hottest topics in neutrino physics. The JSNS$^2$ experiment aims to search for the existence of neutrino oscillations with $\Delta m^2$ near 1 eV$^2$ at the J-PARC Materials and Life Science Experimental Facility (MLF). Read More