Nuclear Theory·nucl-th

Tuesday·January 29, 2019

20 papers—11 primary·9 cross-listed

12
Predictions for energy correlators probing substructure of groomed heavy quark jets
Christopher Lee🇺🇸 · Prashant Shrivastava🇺🇸 · Varun Vaidya🇺🇸
We develop an effective field theory (EFT) framework to perform an analytic calculation for energy correlator observables computed on groomed heavy-quark jets. A soft-drop grooming algorithm is applied to a jet initiated by a massive quark to minimize soft contamination effects such as pile-up and multi-parton interactions. We specifically consider the two-particle energy correlator as an initial application of this EFT framework to compute heavy quark jet substructure. We find that there are different regimes for the event shapes, depending on the size of the measured correlator observable, that require the use of different EFT formulations, in which the quark mass and grooming parameters may be relevant or not. We use the EFT to resum large logarithms in the energy correlator observable in terms of the momentum of a reconstructed heavy hadron to NLL $^{'}$ accuracy and subsequently match it to a full QCD $O (α_{s})$ cross section, which we also compute. We compare our predictions to simulations in PYTHIA for $e^{+} e^{-}$ collisions. We find a good agreement with partonic simulations, as well as hadronic ones with an appropriate shape function used to describe nonperturbative effects and the heavy quark hadron decay turned off. We also predict the scaling behavior for the leading nonperturbative power correction due to hadronization. Consequently, we can give a prediction for the energy correlator distribution at the level of the reconstructed heavy hadron. This work provides a general framework for the analysis of heavy quark jet substructure observables.
↳ hep-phnucl-thJHEP(2019)·43 citations
13
Heavy quark spin multiplet structure of $P_{c}$ -like pentaquark as P-wave hadronic molecular state
Yuki Shimizu🇯🇵 · Yasuhiro Yamaguchi🇯🇵 · Masayasu Harada🇯🇵
We study the heavy quark spin (HQS) multiplet structure of P-wave $Q Q ˉ q q q$ -type pentaquarks treated as molecules of a heavy meson and a heavy baryon. We define the light-cloud spin (LCS) basis decomposing the meson-baryon spin wavefunction into the LCS and HQS parts. Introducing the LCS basis, we find HQS multiplets classified by the LCS; five HQS singlets, two HQS doublets, and three HQS triplets. We construct the one-pion exchange potential respecting the heavy quark spin and chiral symmetries to demonstrate which HQS multiplets are realized as a bound state. By solving the coupled channel Schrödinger equations, we study the heavy meson-baryon systems with $I = 1/2$ and $J^{P} = (1/ 2^{+}, 3/ 2^{+}, 5/ 2^{+}, 7/ 2^{+})$ . The bound states which have same LCS structure are degenerate at the heavy quark limit, and the degeneracy is resolved for finite mass. This HQS multiplet structure will be measured in the future experiments.
↳ hep-phnucl-thPTEP(2019)·12 citations
14
Coherence Optimization in Neutron Interferometry through Defocussing
J. Nsofini🇨🇦 · D. Sarenac🇨🇦 · D. G. Cory🇨🇦 · D. A. Pushin🇨🇦
A zero-area four-blade perfect crystal neutron interferometer (NI) possess a decoherence-free subspace (DFS) for low-frequency mechanical vibrations and thus is easier to site. %has the potential to broaden the application of crystal-based neutron interferometry to a higher number of neutron sources. However, unlike the standard three-blade Mach-Zehnder NI the ideal contrast of this four-blade NI geometry is less than one. By applying a recently introduced quantum information model for dynamical diffraction we show that the contrast for the four-blade DFS NI can be increased by offsetting the focusing condition. The contrast optimization leads to an NI geometry where the distances between the centers of the blades are equidistant. An experiment is proposed to verify the increase in contrast.
↳ quant-phcs.ITmath.ITnucl-thPRA(2019)·4 citations
15
Updated analysis of recent results on electron and positron elastic scattering on proton
V. V. Bytev🇷🇺 · E. Tomasi-Gustafsson🇫🇷
We discuss recent experimental results concerning the cross section ratio of positron over electron elastic scattering on protons, and compare with the predictions of a pre-existent calculation. The deviation from unity of this ratio, $i . e .$ , a charge asymmetry different from zero, is the signature of contributions beyond the Born approximation. After reviewing the published results, we compare the elastic data to a calculation which includes the diagram corresponding to two-photon exchange. It turns out that all the data on the cross section ratio, in the limit of their precision, do not show evidence of enhanced two-photon contribution beyond the expected percent level. Our results confirm that experimental evidence for a large contribution of two-photon exchange is not yet found.
↳ hep-phnucl-thPRC(2019)·10 citations
16
Elastic proton-proton scattering at LHC energies in holographic QCD
Wei Xie🇨🇳 · Akira Watanabe🇨🇳 · Mei Huang🇨🇳
The cross sections of the high energy proton-proton scattering are studied in a holographic QCD model, focusing on the Regge regime. In our model setup, the involved nonperturbative partonic dynamics is described by the Pomeron exchange, which is realized by applying the Reggeized spin-2 particle propagator together with the proton gravitational form factor obtained from the bottom-up AdS/QCD model. Our model includes three adjustable parameters which are to be fitted by experimental data. We show that both the resulting differential and total cross sections are consistent with data, including the ones recently measured at $s = 13$ TeV by the TOTEM collaboration at the LHC. Our results imply that the present framework works well in the considered TeV scale, and further applications to other high energy scattering processes, in which the involved strong interaction can be approximated by the Pomeron exchange, are possible.
↳ hep-phhep-thnucl-exnucl-thJHEP(2019)·26 citations
17
Spin polarization evolution in a boost invariant hydrodynamical background
Wojciech Florkowski🇵🇱 · Avdhesh Kumar🇵🇱 · Radoslaw Ryblewski🇵🇱 · Rajeev Singh🇵🇱
Relativistic hydrodynamic equations for particles with spin one-half are used to determine the space-time evolution of the spin polarization in a boost-invariant and transversely homogeneous background. The hydrodynamic approach uses the forms of the energy-momentum and spin tensors based on de Groot, van Leeuwen, and van Weert formalism. Our calculations illustrate how the formalism of hydrodynamics with spin can be used to determine physical observables related to the spin polarization and how the latter can be compared with the experimental data.
↳ hep-phnucl-thPRC(2019)·110 citations
18
Excited-State Quantum Phase Transitions in Bosonic Lattice Systems
Michal Macek
Concentrating on bosonic lattice systems, we ask whether and how Excited State Quantum Phase Transition (ESQPT) singularities occur in condensed matter systems with ground state QPTs. We study in particular the spectral singularities above the ground-state phase diagram of the boson Hubbard model. As a general prerequisite, we point out the analogy between ESQPTs and van Hove singularities (vHss).
↳ cond-mat.mes-hallcond-mat.quant-gasnucl-thAIP Conf.Proc.(2019)·1 citation
19
Neutron skin and signature of the $N$ = 14 shell gap found from measured proton radii of $^{17 - 22}$ N
S. Bagchi · R. Kanungo · W. Horiuchi · G. Hagen · T. D. Morris · S. R. Stroberg · T. Suzuki · F. Ameil · J. Atkinson · Y. Ayyad · D. Cortina-Gil · I. Dillmann and 28 other authors
A thick neutron skin emerges from the first determination of root mean square radii of the proton distributions for $^{17 - 22}$ N from charge changing cross section measurements around 900 $A$ MeV at GSI. Neutron halo effects are signaled for $^{22}$ N from an increase in the proton and matter radii. The radii suggest an unconventional shell gap at $N$ = 14 arising from the attractive proton-neutron tensor interaction, in good agreement with shell model calculations. $A b$ $ini t i o$ , in-medium similarity re-normalization group, calculations with a state-of-the-art chiral nucleon-nucleon and three-nucleon interaction reproduce well the data approaching the neutron drip-line isotopes but are challenged in explaining the complete isotopic trend of the radii.
↳ nucl-exnucl-thPLB(2019)·55 citations
20
Phenomenological NLO analysis of eta(c) production at the LHC in the collider and fixed-target modes
Yu Feng🇨🇳 · Jibo He🇫🇷 · Jean-Philippe Lansberg🇫🇷 · Hua-Sheng Shao🇫🇷 · Andrii Usachov🇫🇷 · Hong-Fei Zhang🇨🇳
In view of the good agreement between the LHCb prompt-eta(c) data at sqrt(s)=7 and 8 TeV and the NLO colour-singlet model predictions --i.e. the leading v^2 NRQCD contribution--, we provide predictions in the LHCb acceptance for the forthcoming 13 TeV analysis bearing on data taken during the LHC Run2. We also provide predictions for sqrt(s)=115 GeV for proton-hydrogen collisions in the fixed-target mode which could be studied during the LHC Run3. Our predictions are complemented by a full theoretical uncertainty analysis. In addition to cross section predictions, we elaborate on the uncertainties on the p bar-p branching ratio --necessary for data-theory comparison-- and discuss other usable branching fractions for future studies.
↳ hep-phhep-exnucl-exnucl-thNPB(2019)·28 citations

Affiliations

first authorsco-authorsvia INSPIRE