Nuclear Theory·nucl-th

Tuesday·May 21, 2019

11 papers—5 primary·6 cross-listed

06
[Submitted on 17 May 2019] (cross-list from hep-ph)
Subleading Power Factorization with Radiative Functions
Ian Moult🇺🇸 · Iain W. Stewart🇺🇸 · Gherardo Vita🇺🇸
The study of amplitudes and cross sections in the soft and collinear limits allows for an understanding of their all orders behavior, and the identification of universal structures. At leading power soft emissions are eikonal, and described by Wilson lines. Beyond leading power the eikonal approximation breaks down, soft fermions must be added, and soft radiation resolves the nature of the energetic partons from which they were emitted. For both subleading power soft gluon and quark emissions, we use the soft collinear effective theory (SCET) to derive an all orders gauge invariant bare factorization, at both amplitude and cross section level. This yields universal multilocal matrix elements, which we refer to as radiative functions. These appear from subleading power Lagrangians inserted along the lightcone which dress the leading power Wilson lines. The use of SCET enables us to determine the complete set of radiative functions that appear to $O (λ^{2})$ in the power expansion, to all orders in $α_{s}$ . For the particular case of event shape observables in $e^{+} e^{-} \to$ dijets we derive how the radiative functions contribute to the factorized cross section to $O (λ^{2})$ .
Comments:
62 pages + appendices, many pretty and colorful figures. v2: journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1905.07411 [pdf]
JHEP(2019)·91 citations
07
[Submitted on 17 May 2019] (cross-list from hep-ph)
Event shape and Multiplicity dependence of Freeze-out Scenario and System Thermodynamics in Proton+Proton Collisions at $s$ = 13 TeV using PYTHIA8
Sushanta Tripathy🇮🇳 · Ashish Bisht🇮🇳 · Raghunath Sahoo🇮🇳 · Arvind Khuntia🇵🇱 · Malavika Panikkassery Salvan🇮🇳
Recent observations of QGP-like conditions in high-multiplicity pp collisions from ALICE experiment at the LHC warrants an introspection whether to use pp collisions as a baseline measurement to characterize heavy-ion collisions for possible formation of a Quark-Gluon Plasma. A double differential study of the particle spectra and thermodynamics of the produced system as a function of charged-particle multiplicity and transverse spherocity in pp collisions would shed light into the underlying event dynamics. Transverse spherocity, one of the event shape observables, allows to separate the events in terms of jetty and isotropic events. We analyse the identified particle transverse momentum ( $p_{T}$ ) spectra as a function of charged-particle multiplicity and transverse spherocity using Tsallis non-extensive statistics and Boltzmann-Gibbs Blastwave (BGBW) model in pp collisions at $s$ = 13 TeV using PYTHIA8 event generator. The extracted parameters such as temperature ( $T$ ), radial flow ( $β$ ) and non-extensive parameter ( $q$ ) are shown as a function of charged-particle multiplicity for different spherocity classes. We observe that the isotropic events approach to thermal equilibrium while the jetty ones remain far from equilibrium. We argue that, while studying the QGP-like conditions in small systems, one should separate the isotropic events from the spherocity-integrated events, as the production dynamics are different.
Comments:
Same as the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1905.07418 [pdf]
Adv.High Energy Phys.(2021)·28 citations
08
[Submitted on 19 May 2019] (cross-list from hep-th)
Thermal Diffusion and Quantum Chaos in Neutral Magnetized Plasma
Wei Li🇹🇼 · Shu Lin🇨🇳 · Jiajie Mei🇨🇳
We calculate the thermal diffusion constant $D_{T}$ and butterfly velocity $v_{B}$ in neutral magnetized plasma using holographic magnetic brane background. We find the thermal diffusion constant satisfies Blake's bound. The constant in the bound $D_{T} 2 π T / v_{B}^{2}$ is a decreasing function of magnetic field. It approaches one half in the large magnetic field limit. We also find the existence of a special point defined by Lyapunov exponent and butterfly velocity on which pole-skipping phenomenon occurs.
Comments:
20 pages, 3 figures
Subjects:
High Energy Physics — Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
1905.07684 [pdf]
PRD(2019)·32 citations
09
[Submitted on 19 May 2019] (cross-list from hep-ph)
Mass shifts of $^{3} P_{J}$ heavy quarkonia due to the effect of two-gluon annihilation
Hui-Yun Cao🇨🇳 · Hai-Qing Zhou🇨🇳
In this work, we calculate the nonrelativistic asymptotic behavior of the amplitudes of $q q \to 2 g \to q q$ in the leading order of $α_{s}$ (LO- $α_{s}$ ) with $q q$ in the $^{3} P_{J}$ channels. In the practical calculation we take the momenta of quarks and antiquarks on-shell and expand the amplitudes on the three-momentum of the quarks and antiquarks to order 6 and get three nonzero terms. The imaginary parts of the first term and the second term are the old. The real parts of the results have IR divergence. When applying the results to the heavy quarkonia, the corresponding amplitude of $q q \to 1 g \to q q$ with $q q$ in the color octet $^{3} S_{1}$ channel is considered to absorb the IR divergence in a unitary way in the leading order of $v$ (LO- $v$ ). The finial results can be used to estimate the mass shifts of the $^{3} P_{J}$ heavy quarkonia due to the effect of two-gluon annihilation. The numerical estimation shows that the contributions to the mass shifts of $χ_{c 0, c 1, c 2}$ are about $1.23 \sim 1.58$ MeV, $1.57 \sim 1.86$ MeV and $5.92 \sim 5.45$ MeV when taking $α_{s} \approx 0.25 \sim 0.35$ .
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1905.07708 [pdf]
PRD(2019)·1 citation
10
[Submitted on 20 May 2019] (cross-list from hep-th)
Deep Inelastic Scattering on an Extremal RN-AdS Black Hole II: Holographic Fermi Surface
Kiminad A. Mamo🇺🇸 · Ismail Zahed🇺🇸
We consider deep inelastic scattering (DIS) on a dense nucleus described as an extremal RN-AdS black hole with holographic quantum fermions in the bulk. We evaluate the 1-loop fermion contribution to the R-current on the charged black hole, and map it on scattering off a Fermi surface of a dense and large nucleus with fixed atomic number. Near the black hole horizon, the geometry is that of AdS $_{2} \times$ R $^{3}$ where the fermions develop an emergent Fermi surface with anomalous dimensions. DIS scattering off these fermions yields to anomalous partonic distributions mostly at large-x, as well as modified hard scattering rules. The pertinent R-ratio for the black hole is discussed. For comparison, the structure functions and the R-ratio in the probe or dilute limit with no back-reaction on the geometry, are also derived. We formulate a hybrid holographic model for DIS scattering on heavy and light nuclei, which compares favorably to the existing data for Pb, Au, Fe, C and He over a wide range of parton-x.
Comments:
26 pages, 7 figures; 30 pages, 12 figures, a new section VII is added where a comparison to the experimental data is made with good agreement
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1905.07864 [pdf]
PRD(2020)·6 citations
11
[Submitted on 20 May 2019] (cross-list from hep-ph)
System size and Multiplicity dependence of Chemical freeze-out parameters at the Large Hadron Collider Energies
Rutuparna Rath🇮🇳 · Arvind Khuntia🇵🇱 · Raghunath Sahoo🇮🇳
The collision system and multiplicity dependence of chemical freeze-out temperature ( $T_{ch}$ ) and strangeness saturation factor ( $γ_{s}$ ) are obtained by studying the particle ratios at the Large Hadron Collider (LHC) energies. Here, we consider the new results in pp at 13 TeV, p+Pb at $s_{NN}$ = 5.02 TeV, Xe+Xe at $s_{NN}$ = 5.44 TeV and Pb+Pb at $s_{NN}$ = 5.02 TeV along with the earlier results in pp at $s$ = 7 TeV and Pb+Pb at $s_{NN}$ = 2.76 TeV. A statistical thermal model is used to extract the chemical freeze-out parameters in different multiplicity classes. To understand the particle production from small to large collision systems two ensembles namely, canonical and grand canonical have been considered in this study. A clear observation of multiplicity dependence of $T_{ch}$ and $γ_{s}$ is observed. The values obtained in high-multiplicity pp collisions are found to be similar to the peripheral Pb+Pb collisions. A final state midrapidity charged particle multiplicity density of around 20-30 appears to be a threshold below which, the chemical freeze-out temperature is lower than the kinetic freeze-out temperature.
Comments:
8 pages and 8 figures. This version includes additionally, a comparison between chemical and kinetic freeze-out temperatures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1905.07959 [pdf]
5 citations

Affiliations

first authorsco-authorsvia INSPIRE

Subleading Power Factorization with Radiative Functions

Event shape and Multiplicity dependence of Freeze-out Scenario and System Thermodynamics in Proton+Proton Collisions at s​ = 13 TeV using PYTHIA8

Thermal Diffusion and Quantum Chaos in Neutral Magnetized Plasma

Mass shifts of 3PJ​ heavy quarkonia due to the effect of two-gluon annihilation

Deep Inelastic Scattering on an Extremal RN-AdS Black Hole II: Holographic Fermi Surface

System size and Multiplicity dependence of Chemical freeze-out parameters at the Large Hadron Collider Energies

Affiliations

Event shape and Multiplicity dependence of Freeze-out Scenario and System Thermodynamics in Proton+Proton Collisions at $s$ = 13 TeV using PYTHIA8

Mass shifts of $^{3} P_{J}$ heavy quarkonia due to the effect of two-gluon annihilation