Nuclear Theory·nucl-th

Monday·November 21, 2022

11 papers—2 primary·9 cross-listed

03
Non-equilibrium evolution of quarkonium in medium in the open quantum system approach
Michael Strickland🇺🇸
In this proceedings contribution, I review recent work that aims to provide a more comprehensive and systematic understanding of bottomonium dynamics in the quark-gluon plasma using an open quantum system (OQS) approach that is applied in the framework of the potential non-relativistic QCD (pNRQCD) effective field theory and coupled to realistic hydrodynamical backgrounds that have been tuned to soft hadron observables. I review how the computation of bottomonium suppression can be reduced to solving a Gorini-Kossakowski-Sudarshan-Lindblad (GKSL) equation for the evolution of the b-bbar reduced density matrix, which includes both singlet and octet states plus medium-induced transitions between them at next-to-leading order (NLO) in the binding energy over temperature. Finally, I present comparisons of phenomenological predictions of the NLO OQS+pNRQCD approach and experimental data for bottomonium suppression and elliptic flow in LHC 5.02 TeV Pb-Pb collisions obtained using both smooth and fluctuating hydrodynamic initial conditions.
↳ hep-phnucl-th1 citation
04
Origin of the Proton Mass
Craig D. Roberts🇨🇳
Atomic nuclei lie at the core of everything visible; and at the first level of approximation, their atomic weights are simply the sum of the masses of all the neutrons and protons (nucleons) they contain. Each nucleon has a mass $m_{N} \approx 1 GeV \approx 2000$ -times the electron mass. The Higgs boson -- discovered at the large hadron collider in 2012, a decade ago -- produces the latter, but what generates the nucleon mass? This is a pivotal question. The answer is widely supposed to lie within quantum chromodynamics (QCD), the strong-interaction piece of the Standard Model. Yet, it is far from obvious. In fact, removing Higgs-boson couplings into QCD, one arrives at a scale invariant theory, which, classically, can't support any masses at all. This contribution sketches forty years of developments in QCD, which suggest a solution to the puzzle, and highlight some of the experiments that can validate the picture.
↳ hep-phhep-exhep-latnucl-ex+1EPJ Web Conf.(2023)·25 citations
05
Exploring the Phase Diagram of V-QCD with Neutron Star Merger Simulations
Tuna Demircik🇵🇱 · Christian Ecker🇩🇪 · Matti Järvinen🇰🇷 · Luciano Rezzolla🇩🇪 · Samuel Tootle🇩🇪 · Konrad Topolski🇩🇪
Determining the phase structure of Quantum Chromodynamics (QCD) and its Equation of State (EOS) at densities and temperatures realized inside neutron stars and their mergers is a long-standing open problem. The holographic V-QCD framework provides a model for the EOS of dense and hot QCD, which describes the deconfinement phase transition between a dense baryonic and a quark matter phase. We use this model in fully general relativistic hydrodynamic (GRHD) simulations to study the formation of quark matter and the emitted gravitational wave signal of binary systems that are similar to the first ever observed neutron star merger event GW170817.
↳ astro-ph.HEgr-qchep-phnucl-thEPJ Web Conf.(2022)·10 citations
06
Three-particle Lellouch-Lüscher formalism in moving frames
Fabian Müller🇩🇪 · Jin-Yi Pang🇨🇳 · Akaki Rusetsky🇩🇪 · Jia-Jun Wu🇨🇳
A manifestly relativistic-invariant Lellouch-Lüscher formalism for the three-particle decays is proposed. Similarly to ref.[1], the formalism is based on the use of the non-relativistic effective Lagrangians. Manifest Lorentz invariance is guaranteed, as in ref.[2], by choosing the quantization axis along the total four-momentum of the three-particle system. A systematic inclusion of the higher-order derivative couplings, as well as higher partial waves is addressed.
↳ hep-lathep-phnucl-thJHEP(2023)·30 citations
07
Negative heat capacity for hot nuclei: confirmation with formulation from the microcanonical ensemble
B. Borderie · S. Piantelli · J. D. Frankland · N. Le Neindre
By using freeze-out properties of multifragmenting hot nuclei produced in quasifusion central $^{129}$ Xe+ $^{na t}$ Sn collisions at different beam energies (32, 39, 45 and 50 AMeV) which were estimated by means of a simulation based on experimental data collected by the $4 π$ INDRA multidetector, heat capacity in the thermal excitation energy range 4 - 12.5 AMeV was calculated from total kinetic energies and multiplicities at freeze-out. The microcanonical formulation was employed. Negative heat capacity which indicates a first order phase transition for finite systems is observed and confirms previous results using a different method.
↳ nucl-exnucl-thNuovo Cim.C(2022)·0 citations
08
Medium-induced radiation with vacuum propagation in the pre-hydrodynamics phase
Carlota Andres🇫🇷 · Liliana Apolinário🇵🇹 · Fabio Dominguez🇪🇸 · Marcos Gonzalez Martinez🇪🇸 · Carlos A. Salgado🇪🇸
The recent discovery of the potential of jet quenching observables to constrain the initial stages after a heavy-ion collision makes imperative to have a better understanding of the process of medium-induced radiation before the formation of the quark-gluon plasma (QGP) and its impact on observables at high- $p_{T}$ . In this work, we generalize the BDMPS-Z framework for medium-induced radiation to account for additional emissions occurring before the creation of the QGP. For simplicity, we assume that during the pre-hydrodynamics phase the hard parton propagates as in vacuum. This set-up, allows us to isolate the contribution from the additional initial radiation by comparing with the usual scenarios in which the emitter is created inside the medium but with different starting points. Using both a numerical implementation of the fully resummed emission spectrum and the usual analytical approximations, we find that replacing an initial slab of the medium by vacuum yields to a significant reduction of the emission spectrum for low radiated gluon energies, while the high-energy tails remain largely unmodified. Finally, we assess the effect of replacing the initial medium by vacuum propagation on the single-inclusive particle suppression $R_{AA}$ and high- $p_{T}$ azimuthal asymmetry $v_{2}$ . Our findings indicate that considering vacuum propagation prior to hydrodynamization leads to an increase in the $v_{2}$ , thus corroborating the importance of the treatment of jet quenching in the initial stages for the correct description of both observables.
↳ hep-phnucl-thJHEP(2023)·27 citations
09
Two-photon decay of fully-charmed tetraquarks from light-by-light scattering at the LHC
Volodymyr Biloshytskyi🇩🇪 · Lucian Harland-Lang🇬🇧 · Bogdan Malaescu🇫🇷 · Vladimir Pascalutsa🇩🇪 · Kristof Schmieden🇩🇪 · Matthias Schott🇩🇪
The LHC newly-discovered resonant structures around 7 GeV, such as the $X (6900)$ , could be responsible for the observed excess in light-by-light scattering between 5 and 10 GeV. We show that the ATLAS data for light-by-light scattering may indeed be explained by such a state with the $γ γ$ branching ratio of order of $1 0^{- 4}$ . This is much larger than the value inferred by the vector-meson dominance, but agrees quite well with the tetraquark expectation for the nature of this state. Further light-by-light scattering data in this region, obtained during the ongoing Run-3 and future Run-4 of the LHC, are required to pin down these states in $γ γ$ channel.
↳ hep-phhep-exnucl-thEPJ Web Conf.(2022)·7 citations
10
A new avenue in the search for CP violation: Moessbauer spectroscopy of 227-Ac
M.Scheck · R. Chapman · J.Dobaczewski · C.Ederer · P.Ivanov · G.Lorusso · D.O'Donnell · Ch.Schroeder
This work proposes a new avenue in the search for CP-violating odd-electric and even-magnetic nuclear moments. A promising candidate to find such moments in the ground state is the quadrupole-deformed and octupole-correlated nucleus 227-actinium. In this nucleus, the 27.4-keV $E 1$ ~transition that connects the $3/ 2^{+}$ parity-doublet partner and the $3/ 2^{-}$ ground state is perfectly suited to apply the sensitive technique of recoil-free selfabsorption, commonly known as Mössbauer spectroscopy. In this experimental approach, the lifetime of the $3/ 2^{+}$ upper parity-doublet partner allows an estimate of the lower limit of $Δ E = 2 \cdot Γ_{γ}$ = $23.7 (1) \times 1 0^{- 9}$ eV for the achievable energy resolution to be made. This resolution must be exceeded by the interaction of a CP-violating moment and the corresponding multipole moment of the field distribution in the lattice. This work presents the first ideas for patterns caused by CP-violating moments on the expected quadrupole splitting and nuclear Zeeman effect.
↳ nucl-exnucl-thEPJA(2023)·6 citations
11
Out-of-equilibrium photon production and electric conductivity in a holographic Bjorken expanding plasma
Sebastian Grieninger🇺🇸 · Ismail Zahed🇺🇸
We analytically compute the out-of-equilibrium direct photon production rate and electric conductivity, in a strongly coupled and expanding Bjorken plasma, from holography. Our results are valid at late times where the expanding plasma asymptotes Bjorken hydrodynamics. The out-of-equilibrium rates are substantially harder and larger, early on in the Bjorken expansion phase.
↳ hep-phhep-thnucl-thPRD(2023)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE