Nuclear Theory·nucl-th

Wednesday·March 11, 2020

20 papers—6 primary·14 cross-listed

07
[Submitted on 16 Dec 2019] (cross-list from quant-ph)
Quantum Computer Systems for Scientific Discovery
Yuri Alexeev🇺🇸 · Dave Bacon🇺🇸 · Kenneth R. Brown🇺🇸 · Robert Calderbank🇺🇸 · Lincoln D. Carr🇺🇸 · Frederic T. Chong🇺🇸 · Brian DeMarco🇺🇸 · Dirk Englund🇺🇸 · Edward Farhi🇺🇸 · Bill Fefferman🇺🇸 · Alexey V. Gorshkov🇺🇸 · Andrew Houck🇺🇸 and 12 other authors
The great promise of quantum computers comes with the dual challenges of building them and finding their useful applications. We argue that these two challenges should be considered together, by co-designing full-stack quantum computer systems along with their applications in order to hasten their development and potential for scientific discovery. In this context, we identify scientific and community needs, opportunities, a sampling of a few use case studies, and significant challenges for the development of quantum computers for science over the next 2--10 years. This document is written by a community of university, national laboratory, and industrial researchers in the field of Quantum Information Science and Technology, and is based on a summary from a U.S. National Science Foundation workshop on Quantum Computing held on October 21--22, 2019 in Alexandria, VA.
Subjects:
Quantum Physics (quant-ph); cond-mat.other (cond-mat.other); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1912.07577 [pdf]
PRX Quantum(2021)·291 citations
08
[Submitted on 9 Mar 2020] (cross-list from hep-th)
Entropy production far from equilibrium in a chiral charged plasma in the presence of external electromagnetic fields
Casey Cartwright🇺🇸
We report on the time evolution of a charged strongly coupled $N = 4$ SYM plasma with an axial anomaly subjected to strong electromagnetic fields. The evolution of this plasma corresponds to a fully backreacted asymptotically AdS $_{5}$ solution to the Einstein-Maxwell-Chern-Simons theory. We explore the evolution of the axial current and production of axial charges. As an application we show that after a sufficiently long time both the entropy and the holographic entanglement entropy of a strip-like topology ( both parallel to and transverse to the flow of axial current) grow linearly in time.
Comments:
v2: published version, 32 pages. Major changes including: multiple new images, revisions of the body of the text and discussion throughout the work, two additional appendices and further discussion has been included on the minimal surfaces. Comments are always welcome via email
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2003.04325 [pdf]
JHEP(2021)·16 citations
09
[Submitted on 9 Mar 2020] (cross-list from hep-lat)
The effect of stout smearing on the phase diagram from multiparameter reweigthing in lattice QCD
Matteo Giordano🇭🇺 · Kornel Kapas🇭🇺 · Sandor D. Katz🇭🇺 · Daniel Nogradi🇭🇺 · Attila Pasztor🇭🇺
The phase diagram and the location of the critical endpoint (CEP) of lattice QCD with unimproved staggered fermions on a $N_{t} = 4$ lattice was determined fifteen years ago with the multiparameter reweighting method by studying Fisher zeros. We first reproduce the old result with an exact algorithm (not known at the time) and with statistics larger by an order of magnitude. As an extension of the old analysis we introduce stout smearing in the fermion action in order to reduce the finite lattice spacing effects. First we show that increasing the smearing parameter $ρ$ the crossover at $μ = 0$ gets weaker, i.e., the leading Fisher zero gets farther away from the real axis. Furthermore as the chemical potential is increased the overlap problem gets severe sooner than in the unimproved case, therefore shrinking the range of applicability of the method. Nevertheless certain qualitative features remain, even after introducing the smearing. Namely, at small chemical potentials the Fisher zeros first get farther away from the real axis and later at around $a μ_{q} = 0.1 - 0.15$ they start to get closer, i.e., the crossover first gets weaker and later stronger as a function of $μ$ . However, because of the more severe overlap problem the CEP is out of reach with the smeared action.
Comments:
8 pages, 5 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2003.04355 [pdf]
PRD(2020)·17 citations
10
[Submitted on 9 Mar 2020] (cross-list from quant-ph)
Electron interaction with the environment in tunnel ionization
D. Lozano-Gómez · N. G. Kelkar
The average dwell time of an electron in a potential barrier formed by an external electric field and the potential of a helium atom is evaluated within a semi classical one-dimensional tunneling approach. The tunneling electron is considered to interact with a nuclear charge screened by the electron in the helium ion. It is found that screening leads to smaller average dwell times of the tunneling electron. The dissipative effect of the environment on the tunneling electron is taken into account within a semiclassical model involving a velocity dependent frictional force and is found to change the average dwell time significantly.
Comments:
18 pages, 7 figures
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2003.04363 [pdf]
Annals Phys.(2020)·1 citation
11
[Submitted on 9 Mar 2020] (cross-list from hep-ph)
Semileptonic decays of $D_{(s)}$ mesons
Zhao-Qian Yao🇨🇳 · Daniele Binosi🇮🇹 · Zhu-Fang Cui🇨🇳 · Craig D. Roberts🇨🇳 · Shu-Sheng Xu🇨🇳 · Hong-Shi Zong🇨🇳
A symmetry-preserving continuum approach to meson bound-states in quantum field theory, employed elsewhere to describe numerous $π$ - and $K$ -meson electroweak processes, is used to analyse leptonic and semileptonic decays of $D_{(s)}$ mesons. Each semileptonic transition is conventionally characterised by the value of the dominant form factor at $t = 0$ and the following results are obtained herein: $f_{+}^{D_{s} \to K} (0) = 0.673 (40)$ ; $f_{+}^{D \to π} (0) = 0.618 (31)$ ; and $f_{+}^{D \to K} (0) = 0.756 (36)$ . Working with the computed $t$ -dependence of these form factors and standard averaged values for $∣ V_{c d} ∣$ , $∣ V_{cs} ∣$ , one arrives at the following predictions for the associated branching fractions: $B_{D_{s}^{+} \to K^{0} e^{+} ν_{e}} = 3.31 (33) \times 1 0^{- 3}$ ; $B_{D^{0} \to π^{-} e^{+} ν_{e}} = 2.73 (22) \times 1 0^{- 3}$ ; and $B_{D^{0} \to K^{-} e^{+} ν_{e}} = 3.83 (28)$ %. Alternatively, using the calculated $t$ -dependence, agreement with contemporary empirical results for these branching fractions requires $∣ V_{c d} ∣ = 0.221 (9)$ , $∣ V_{u s} ∣ = 0.953 (34)$ . With all $D_{(s)}$ transition form factors in hand, the nature of SU $(3)$ -flavour symmetry-breaking in this array of processes can be analysed; and just as in the $π$ - $K$ sector, the magnitude of such effects is found to be determined by the scales associated with emergent mass generation in the Standard Model, not those originating with the Higgs mechanism.
Comments:
9 pages, 5 figures, 4 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2003.04420 [pdf]
PRD(2020)·18 citations
12
[Submitted on 10 Mar 2020] (cross-list from hep-ph)
Fundamental Properties of the Proton in Light-Front Zero Modes
Xiangdong Ji🇺🇸
For a proton in the infinite momentum frame, its wave function contains a zero-momentum part (light-front zero-modes) originated from the modification of the QCD vacuum in the presence of the valence quarks, exhibiting a light-front long-range order in the quantum state. This ``non-travelling'' component of the proton contributes to its fundamental properties, including the mass and spin, as well as the naive-time-reversal-odd correlations between transverse momentum and spin. The large momentum effective theory (LaMET) provides a theoretical approach to study the physical properties of the proton's zero-mode ``condensate'' through lattice simulations.
Comments:
5 pages, no figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2003.04478 [pdf]
NPB(2020)·41 citations
13
[Submitted on 10 Mar 2020] (cross-list from hep-ph)
Fluctuating temperature and baryon chemical potential in heavy-ion collisions and the position of the critical end point in the effective QCD phase diagram
Alejandro Ayala🇲🇽 · Saul Hernandez-Ortiz🇲🇽 · Luis A. Hernandez🇲🇽 · Victor Knapp-Perez🇲🇽 · Renato Zamora🇨🇱
We use the linear sigma model with quarks to locate the critical end point in the effective QCD phase diagram accounting for fluctuations in temperature and quark chemical potential. For this purpose, we use the non-equilibrium formalism provided by the superstatistics framework. We compute the effective potential in the high- and low-temperature approximations up to sixth order and include the contribution of ring diagrams to account for plasma screening effects. We fix the model parameters from relations between the thermal sigma and pion masses imposing a first order phase transition at zero temperature and a finite critical value for the baryon chemical potential that we take of order of the nucleon mass. We find that the CEP displacement due to fluctuations in temperature and/or quark chemical potential is almost negligible.
Comments:
15 pages, 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2003.04505 [pdf]
PRD(2020)·14 citations
14
[Submitted on 10 Mar 2020] (cross-list from hep-ph)
Light-quark flavours in a triangle
Renxin Xu (PKU)🇨🇳
All of the light flavors seem to work well for bulk strong matter at pressure free, which could be manifested diversely in the form of compact star and strange nugget. Observational tests are discussed.
Comments:
3 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2003.04506 [pdf]
SCPMA(2020)·7 citations
15
[Submitted on 10 Mar 2020] (cross-list from hep-ph)
Second-order Charge Currents and Stress Tensor in Chiral System
Shi-Zheng Yang🇨🇳 · Jian-Hua Gao🇨🇳 · Zuo-Tang Liang🇨🇳 · Qun Wang🇨🇳
We solve the Wigner equation for massless spin-1/2 charged fermions near global equilibrium. The Wigner function can be obtained order by order in the power expansion of the vorticity and electromagnetic field. The Wigner function has been derived up to the second order from which the non-dissipative charge currents and the stress tensor can be obtained. The charge and energy densities and the pressure have contributions from the vorticity and electromagnetic field at the second order. The vector and axial Hall currents can be induced along the direction orthogonal to the vorticity and electromagnetic field at the second order. We also find that the trace anomaly emerges natually in renormalizing the stress tensor by including the quantum correction from the electromagnetic field.
Comments:
31 pages, no figures, accepted version, general solution derived, more detail and more references added
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2003.04517 [pdf]
PRD(2020)·27 citations
16
[Submitted on 10 Mar 2020] (cross-list from hep-ph)
Isentropic evolution of the matter in heavy-ion collisions and the search for the critical endpoint
Mario Motta🇮🇹 · Rainer Stiele🇮🇹 · Wanda Maria Alberico🇮🇹 · Andrea Beraudo🇮🇹
We study the isentropic evolution of the matter produced in relativistic heavy-ion collisions for various values of the entropy-per-baryon ratio of interest for the ongoing and future experimental searches for the critical endpoint (CEP) in the QCD phase diagram: these includes the current Beam-Energy-Scan (BES) program at RHIC and the fixed-target collisions foreseen for the near future at various facilities. We describe the hot-dense matter through two different effective Lagrangians: the PNJL (Polyakov-Nambu-Jona-Lasinio) and the PQM (Polyakov-quark-meson) models. We focus on quantities expected to have a direct experimental relevance: the speed of sound, responsible for the collective acceleration of the fireball, and the generalized susceptibilities, connected to the cumulants of the distributions of conserved charges. In principle, they should affect the momentum spectra and the event-by-event fluctuations of the yields of identified particles. Taking realistic values for the initial temperature and the entropy-per-baryon ratio we study the temporal evolution of the above quantities looking for differences along isentropic trajectories covering different regions of the QCD phase diagram, passing far or close to the CEP or even intersecting the first-order critical line.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2003.04734 [pdf]
EPJC(2020)·22 citations
17
[Submitted on 10 Mar 2020] (cross-list from hep-ph)
Extracting the Transverse Momentum Dependent Polarizing Fragmentation Functions
Daniel Callos🇺🇸 · Zhong-Bo Kang🇺🇸 · John Terry🇺🇸
We demonstrate that spontaneous transverse polarization of Lambda baryon ( $Λ$ ) production in $e^{+} e^{-}$ annihilation can be described using the transverse momentum dependent polarizing fragmentation functions (TMD PFFs). Using a simple Gaussian model, we perform an extraction of the TMD PFFs by fitting the BELLE collaboration's recent measurement of the $Λ$ transverse polarization in back-to-back $Λ + h$ production in $e^{+} e^{-}$ collisions, $e^{-} + e^{+} \to Λ^{↑} + h + X$ . We find that this simple model accurately describes the experimental data for $Λ$ production associated with pions and kaons, and we are able to determine TMD PFFs for different quark flavors. We use these newly extracted TMD PFFs to make predictions for the transverse polarization of $Λ$ produced in semi-inclusive deep inelastic scattering at a future electron-ion collider, and find that such a polarization is around $10%$ and should be measurable.
Comments:
9 pages, 7 figures, updated fit and improved text
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2003.04828 [pdf]
PRD(2020)·66 citations
18
[Submitted on 10 Mar 2020] (cross-list from hep-ph)
Covariant model for the Dalitz decay of the $N (1535)$ resonance
G. Ramalho🇧🇷 · M.T. Peña🇵🇹
We develop a covariant model for the $γ^{*} N \to N (1535)$ transition in the timelike kinematical region, the region where the square momentum transfer $q^{2}$ is positive. Our starting point is the covariant spectator quark model constrained by data in the spacelike kinematical region ( $Q^{2} = - q^{2} > 0$ ). The model is used to estimate the contributions of valence quarks to the transition form factors, and one obtains a fair description of the Dirac form factor at intermediate and large $Q^{2}$ . For the Pauli form factor there is evidence that beyond the quark-core contributions there are also significant contributions of meson cloud effects. Combining the quark-core model with an effective description of the meson cloud effects, we derive a parametrization of the spacelike data that can be extended covariantly to the timelike region. This extension enabled us to estimate the Dalitz decay widths of the $N (1535)$ resonance, among other observables. Our calculations can help in the interpretation of the present experiments at HADES ( $pp$ collisions and others).
Comments:
23 pages, 17 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2003.04850 [pdf]
PRD(2020)·26 citations
19
[Submitted on 10 Mar 2020] (cross-list from astro-ph.HE)
Nonparametric constraints on neutron star matter with existing and upcoming gravitational wave and pulsar observations
Philippe Landry🇺🇸 · Reed Essick🇺🇸 · Katerina Chatziioannou🇺🇸
Observations of neutron stars, whether in binaries or in isolation, provide information about the internal structure of the most extreme material objects in the Universe. In this work, we combine information from recent observations to place joint constraints on the properties of neutron star matter. We use (i) lower limits on the maximum mass of neutron stars obtained through radio observations of heavy pulsars, (ii) constraints on tidal properties inferred through the gravitational waves neutron star binaries emit as they coalesce, and (iii) information about neutron stars' masses and radii obtained through X-ray emission from surface hot spots. In order to combine information from such distinct messengers while avoiding the kind of modeling systematics intrinsic to parametric inference schemes, we employ a nonparametric representation of the neutron-star equation of state based on Gaussian processes conditioned on nuclear theory models. We find that existing astronomical observations imply $R_{1.4} = 12.3 2_{- 1.47}^{+ 1.09} km$ for the radius of a $1.4 M_{⊙}$ neutron star and $p (2 ρ_{nuc}) = 3. 8_{- 2.9}^{+ 2.7} \times 1 0^{34} dyn / cm^{2}$ for the pressure at twice nuclear saturation density at the 90% credible level. The upper bounds are driven by the gravitational wave observations, while X-ray and heavy pulsar observations drive the lower bounds. Additionally, we compute expected constraints from potential future astronomical observations and find that they can jointly determine $R_{1.4}$ to $O (1) km$ and $p (2 ρ_{nuc})$ to 80% relative uncertainty in the next five years.
Comments:
22 pages, 11 figures; added figure with sound speed constraints, matches the published version; Zenodo data release DOI:10.5281/zenodo.4678702
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2003.04880 [pdf]
PRD(2020)·374 citations
20
[Submitted on 10 Mar 2020] (cross-list from hep-ph)
Hadronic vacuum polarization: $(g - 2)_{μ}$ versus global electroweak fits
Andreas Crivellin🇨🇭 · Martin Hoferichter🇨🇭 · Claudio Andrea Manzari🇨🇭 · Marc Montull🇨🇭
Hadronic vacuum polarization (HVP) is not only a critical part of the Standard Model (SM) prediction for the anomalous magnetic moment of the muon $(g - 2)_{μ}$ , but also a crucial ingredient for global fits to electroweak (EW) precision observables due to its contribution to the running of the fine-structure constant encoded in $Δ α_{had}^{(5)}$ . We find that with modern EW precision data, including the measurement of the Higgs mass, the global fit alone provides a competitive, independent determination of $Δ α_{had}^{(5)}_{EW} = 270.2 (3.0) \times 1 0^{- 4}$ . This value actually lies below the range derived from $e^{+} e^{-} \to hadrons$ cross-section data, and thus goes into the opposite direction as would be required if a change in HVP were to bring the SM prediction for $(g - 2)_{μ}$ into agreement with the Brookhaven measurement. Depending on the energy where the bulk of the changes in the cross section occurs, reconciling experiment and SM prediction for $(g - 2)_{μ}$ by adjusting HVP would thus not necessarily weaken the case for physics beyond the SM (BSM), but to some extent shift it from $(g - 2)_{μ}$ to the EW fit. We briefly explore some options of BSM scenarios that could conceivably explain the ensuing tension.
Comments:
7 pages, 2 figures; journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2003.04886 [pdf]
PRL(2020)·266 citations

Affiliations

first authorsco-authorsvia INSPIRE