Thu·Nov 21, 2019Thursday·November 21, 2019

1. 01*

   Multiple scattering production of lepton-pairs in ultraperipheral heavy-ion collisions

   Sevgi Karadağ🇹🇷 · Mehmet Cem Güçlü🇹🇷

   Ultra-relativistic peripheral collisions of heavy ions at LHC can produce copies of numbers of lepton pairs via the two-photon process. Since the energy of the heavy ions is so high, multi-pair production cross-sections of the light leptons especially electrons are quite large so that it is possible to measure them experimentally. To calculate the multi-pair production probabilities, first, we should have an impact parameter dependence cross-section. We have obtained a well-behaved impact parameter dependence cross-section and by using the Monte-Carlo methods, we have calculated multi-pair production cross-sections of electrons and muons in Pb-Pb heavy-ion collisions at LHC energies. We have also used some experimental restrictions in our calculation to compare our findings with the experimental results.

   hep-phPRC(2020)·9 citations
2. 02*

   Refined analysis on the parton distribution functions of the proton

   X. G. Wang🇦🇺 · A. W. Thomas🇦🇺

   We explore the application of a two-component model of proton structure functions in the analysis of deep-inelastic scattering (DIS) data at low $Q^2$ and small $x$. This model incorporates both vector meson dominance and the correct photo-production limit. The CJ15 parameterization is applied to the QCD component, in order to take into account effects of order $1/Q^2$ effects, such as target mass corrections and higher twist contributions. The parameters of the leading twist parton distribution functions and higher twist coefficient functions are determined by fitting deep inelastic scattering data. The second moments of the parton distribution functions are extracted and compared with other global fits and lattice determinations.

   hep-phnucl-thJ.Phys.G(2020)·4 citations
3. 03*

   Electron EM-mass melting in strong fields

   Stefan Evans🇺🇸 · Johann Rafelski🇺🇸

   We study the response of the electron mass to an externally applied electrical field. As a consequence of nonlinear electromagnetic (EM) effective action, the mass of a particle diminishes in the presence of an externally applied electric field. We consider modification of the muon anomalous magnetic moment $g-2$ due to electron loop insert in higher order. Since the virtual electron pair is in close proximity to the muon, it experiences strong field phenomena. We show that the current theory-experiment muon $g-2$ discrepancy could originate in the (virtual) electron mass \textit{non-perturbative} modification by the strong muon EM field. The magnitude of the electron mass modification can be also assessed via enhancement of $e^{+}{e}^{-}$-pair production in strong fields.

   hep-phPRD(2020)·3 citations
4. 04*

   Probing Long-lived Particles at Higgs Factories

   Kingman Cheung🇹🇼 · Zeren Simon Wang🇰🇷

   We study displaced vertex signatures of long-lived particles (LLPs) from exotic Higgs decays in the context of a Higgs-portal model and a neutral-naturalness model at the CEPC and FCC-ee. Such two models feature two representative mass ranges for LLPs, which show very different behavior in their decay signatures. The Higgs-portal model contains a very light sub-GeV scalar boson stemming from a singlet scalar field appended to the Standard Model. Such a light scalar LLP decays into a pair of muons or pions, giving rise to a distinctive signature of collimated muon-jet or pion-jet, thanks to the sub-GeV mass. On the other hand, the neutral-naturalness model, e.g., folded supersymmetry, predicts the lightest mirror glueball of mass $O(10)$ GeV, giving rise to long decays with a large transverse impact parameter because of the relatively large mass. Utilizing such distinct characteristics to remove the background, we estimate the sensitivities of searches for light scalar bosons and mirror glueballs at the CEPC and FCC-ee. We find either complementary or stronger coverage compared to the previous results in the similar contexts.

   hep-phPRD(2020)·22 citations
5. 05*

   The $\varphi$ meson with finite momentum in a dense medium

   HyungJoo Kim🇰🇷 · Philipp Gubler🇯🇵

   The dispersion relation of the $\varphi$ meson in nuclear matter is studied in a QCD sum rule approach. In a dense medium, longitudinal and transverse modes of vector particles can have independently modified dispersion relations due to broken Lorentz invariance. Employing the full set of independent operators and corresponding Wilson coefficients up to operator dimension 6, the $\varphi$ meson QCD sum rules are analyzed with changing densities and momenta. The non-trivial momentum dependence of the $\varphi$ meson mass is found to have opposite signs for the longitudinal and transverse modes. Specifically, the mass is reduced by 5 MeV for the longitudinal mode, while its increase amounts to 7 Mev for the transverse mode, both at a momentum scale of 1 GeV. In an experiment which does not distinguish between longitudinal and transverse polarizations, this could in principle be seen as two separated peaks at large momenta. Taking however broadening effects into account, the momentum dependence will most likely be seen as a small but positive effective mass shift and an increased effective width for non-zero momenta.

   hep-phnucl-thPLB(2020)·44 citations
6. 06*

   Minimal texture of quark mass matrices and precision CKM measurements

   Shivali Kaundal🇮🇳 · Aakriti Bagai🇮🇳 · Gulsheen Ahuja🇮🇳 · Manmohan Gupta🇮🇳

   We have carried out an extensive analysis of all possible minimal texture quark mass matrices implying 169 texture 6 zero combinations. One finds that all these combinations are ruled out, a good number of these analytically, the other possibilities are excluded by the present quark mixing data. Interestingly, even if in future, there are changes in the ranges of the light quark masses, these conclusions remain valid.

   hep-phPTEP(2020)·1 citation
7. 07*

   Unified SU(4) theory for the $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$ anomalies

   Shyam Balaji🇦🇺 · Michael A. Schmidt🇦🇺

   We propose a chiral Pati-Salam theory based on the gauge group $SU(4{)}_C\times SU(2{)}_L\times SU(2{)}_R$. The left-handed quarks and leptons are unified into a fundamental representation of $SU(4{)}_C$, while right-handed quarks and leptons have a separate treatment. The deviations measured in the rare semi-leptonic decays $B\to D^{(\ast )}\tau \bar{\nu }$ are explained by a scalar leptoquark which couples to right-handed fields and is contained in the $SU(4{)}_C\times SU(2{)}_R$ breaking scalar multiplet. The measured deviation of lepton flavor universality in the rare decays $\bar{B}\to {\bar{K}}^{(\ast )}{\ell }^{+}{\ell }^{-}$, $\ell =\mu ,e$ is explained via the $SU(4{)}_C$ leptoquark gauge boson. The model predicts a new sub-GeV scale sterile neutrino which participates in the anomaly and can be searched for in upcoming neutrino experiments. The theory satisfies the current most sensitive experimental constraints and its allowable parameter regions will be probed as more precise measurements from the LHCb and Belle II experiments become available.

   hep-phPRD(2020)·45 citations
8. 08*

   Energy momentum tensor and the D-term in the bag model

   Matt J.Neubelt🇺🇸 · Andrew Sampino🇺🇸 · Jonathan Hudson🇺🇸 · Kemal Tezgin🇺🇸 · Peter Schweitzer🇺🇸

   The energy-momentum tensor (EMT) form factors pave new ways for exploring hadron structure. Especially the D-term related to the EMT form factor D(t) has received a lot of attention due to its attractive physical interpretation in terms of mechanical properties. We study the nucleon EMT form factors and the associated densities in the bag model which we formulate for an arbitrary number of colors Nc and show that the EMT form factors are consistently described in this model in the large-Nc limit. The simplicity of the model allows us to test in a lucid way many theoretical concepts related to EMT form factors and densities including recently introduced concepts like normal and tangential forces, or monopole and quadrupole contributions to the angular momentum distribution. We also study the D-terms of rho-meson, Roper resonance, other N* states and Delta-resonances. Among the most interesting outcomes is the lucid demonstration of the deeper connection of EMT conservation, stability, the virial theorem and the negative sign of the D-term.

   hep-phPRD(2020)·63 citations
9. 09*

   Displaced Vertex and Disappearing Track Signatures in type-III Seesaw

   Sudip Jana🇩🇪 · Nobuchika Okada🇺🇸 · Digesh Raut🇺🇸

   We investigate a prospect of probing the type-III seesaw neutrino mass generation mechanism at various collider experiments by searching for a disappearing track and a displaced vertex signature originating from the decay of $SU(2{)}_L$ triplet fermion ($\Sigma$). Since $\Sigma$ is primarily produced at colliders through the electroweak gauge interactions, its production rate is uniquely determined by its mass. We find that a $\Sigma$ particle with a mass of a few hundred GeV produces a disappearing track signature from the decay of its charged component, which can be searched at the HL-LHC. Furthermore, we show that if the lightest observed neutrino has a mass of around $10^{-9}$ eV, the neutral component of $\Sigma$ can be discovered at the proposed MATHUSLA detector. We also show that the charged component of $\Sigma$ with a mass of a few hundred GeV can be observed at the LHeC and FCC-he as a displaced vertex signature.

   hep-phhep-exEPJC(2022)·36 citations
10. 10*

    Electromagnetic and gravitomagnetic structure and radii of nucleons

    O.V. Selyugin🇷🇺

    Taking into account the PDFs, obtained by different Collaborations, the momentum transfer dependence of GPDs of the nucleons is obtained. The calculated electromagnetic and gravitomagnetic form factors of nucleons are used for the description of different form factors and the nucleons elastic scattering in a wide energy and momentum transfer region with a minimum number of fitting parameters. The electromagnetic and gravitomagnetic radii of the nucleon are calculated using the obtained momentum transfer dependence of GPDs with different forms of PDFs obtained by different Collaborations. The comparison of the calculations, taking into account the PDFs obtained by different Collaborations, of mean square electromagnetic and gravitomagnetic radii of nucleons is made.

    hep-phhep-exEPJ Web Conf.(2019)·3 citations
11. 11*

    OmniFold: A Method to Simultaneously Unfold All Observables

    Anders Andreassen🇺🇸 · Patrick T. Komiske🇺🇸 · Eric M. Metodiev🇺🇸 · Benjamin Nachman🇺🇸 · Jesse Thaler🇺🇸

    Collider data must be corrected for detector effects ("unfolded") to be compared with many theoretical calculations and measurements from other experiments. Unfolding is traditionally done for individual, binned observables without including all information relevant for characterizing the detector response. We introduce OmniFold, an unfolding method that iteratively reweights a simulated dataset, using machine learning to capitalize on all available information. Our approach is unbinned, works for arbitrarily high-dimensional data, and naturally incorporates information from the full phase space. We illustrate this technique on a realistic jet substructure example from the Large Hadron Collider and compare it to standard binned unfolding methods. This new paradigm enables the simultaneous measurement of all observables, including those not yet invented at the time of the analysis.

    hep-phhep-exphysics.data-anstat.MLPRL(2020)·225 citations
12. 12*

    Improved global fit to Non-Standard neutrino Interactions using COHERENT energy and timing data

    Pilar Coloma🇪🇸 · Ivan Esteban🇪🇸 · M. C. Gonzalez-Garcia🇪🇸 · Michele Maltoni🇪🇸

    We perform a global fit to neutrino oscillation and coherent neutrino-nucleus scattering data, using both timing and energy information from the COHERENT experiment. The results are used to set model-independent bounds on four-fermion effective operators inducing non-standard neutral-current neutrino interactions. We quantify the allowed ranges for their Wilson coefficients, as well as the status of the LMA-D solution, for a wide class of new physics models with arbitrary ratios between the strength of the operators involving up and down quarks. Our results are presented for the COHERENT experiment alone, as well as in combination with the global data from oscillation experiments. We also quantify the dependence of our results for COHERENT with respect to the choice of quenching factor, nuclear form factor, and the treatment of the backgrounds.

    hep-phhep-exJHEP(2020)·114 citations
13. 13*

    A QCD Debye mass in a broad temperature range

    M. Laine🇨🇭 · P. Schicho🇨🇭 · Y. Schroder🇨🇱

    The Debye mass sets a scale for the screening of static charges and the scattering of fast charges within a gauge plasma. Inspired by its potential cosmological applications, we determine a QCD Debye mass at 2-loop order in a broad temperature range (1 GeV ... 10 TeV), demonstrating how quark mass thresholds get smoothly crossed. Along the way, integration-by-parts identities pertinent to massive loops at finite temperature are illuminated.

    hep-phPRD(2020)·31 citations
14. 14*

    A low-scale flavon model with a $Z_N$ symmetry

    Tetsutaro Higaki🇯🇵 · Junichiro Kawamura🇺🇸

    We propose a model that explains the fermion mass hierarchy by the Froggatt-Nielsen mechanism with a discrete $Z_N^F$ symmetry. As a concrete model, we study a supersymmetric model with a single flavon coupled to the minimal supersymmetric Standard Model. Flavon develops a TeV scale vacuum expectation value for realizing flavor hierarchy, an appropriate $\mu$-term and the electroweak scale, hence the model has a low cutoff scale. We demonstrate how the flavon is successfully stabilized together with the Higgs bosons in the model. The discrete flavor symmetry $Z_N^F$ controls not only the Standard Model fermion masses, but also the Higgs potential and a mass of the Higgsino which is a good candidate for dark matter. The hierarchy in the Higgs-flavon sector is determined in order to make the model anomaly-free and realize a stable electroweak vacuum. We show that this model can explain the fermion mass hierarchy, realistic Higgs-flavon potential and thermally produced dark matter at the same time. We discuss flavor violating processes induced by the light flavon which would be detected in future experiments.

    hep-phJHEP(2020)·18 citations
15. 15*

    Feynman diagrams and the large charge expansion in $3-\epsilon$ dimensions

    Gil Badel🇨🇭 · Gabriel Cuomo🇨🇭 · Alexander Monin🇨🇭 · Riccardo Rattazzi🇨🇭

    In arXiv:1909.01269 it was shown that the scaling dimension of the lightest charge $n$ operator in the $U(1)$ model at the Wilson-Fisher fixed point in $d=4-\epsilon$ can be computed semiclassically for arbitrary values of $\lambda n$, where $\lambda$ is the perturbatively small fixed point coupling. Here we generalize this result to the fixed point of the $U(1)$ model in $3-\epsilon$ dimensions. The result interpolates continuously between diagrammatic calculations and the universal conformal superfluid regime for CFTs at large charge. In particular it reproduces the expectedly universal $O(n^0)$ contribution to the scaling dimension of large charge operators in $3d$ CFTs.

    ↳ hep-thcond-mat.stat-mechcond-mat.str-elhep-phPLB(2020)·69 citations
16. 16*

    Inflation models in the light of self-interacting sterile neutrinos

    Arindam Mazumdar🇮🇳 · Subhendra Mohanty🇮🇳 · Priyank Parashari🇮🇳

    Short baseline neutrino experiments, like LSND and MiniBooNE experiments, pointed towards the existence of eV mass scale sterile neutrinos. To reconcile sterile neutrinos with cosmology self interaction between sterile neutrinos has been studied. We analysed Planck cosmic microwave background (CMB) data with self-interacting sterile neutrino (SI$\nu$) and study their impact on inflation models. The fit to the CMB data in SI$\nu$ model is as good as the fit to $\Lambda$CDM model. We find that the spectral index ($n_s$) values shift to $0.9361\pm 0.0055$ in SI$\nu$ model. This has significant impact on the validity of different inflation models. For example the Starobinsky and quartic hilltop model, which were allowed within $\Lambda$CDM cosmology, are ruled out. On the other hand some models like natural and Coleman-Weinberg inflation are now favoured. Therefore, the existence of self interacting sterile neutrinos with eV order of mass will play an important role in the selection of correct inflation model.

    ↳ astro-ph.COhep-phPRD(2020)·17 citations
17. 17*

    Improved calculations of electron-ion Bremsstrahlung Gaunt factors for astrophysical applications

    Jens Chluba🇬🇧 · Andrea Ravenni🇬🇧 · Boris Bolliet🇬🇧

    Electron-ion Bremsstrahlung (free-free) emission and absorption occur in many astrophysical plasmas for a wide range of physical conditions. This classical problem has been studied multiple times, and many analytical and numerical approximations exist. However, accurate calculations of the transition from the non-relativistic to the relativistic regime remain sparse. Here we provide a comprehensive study of the free-free Gaunt factors for ions with low charge (Z<=10). We compute the Gaunt factor using the expressions for the differential cross section given by Elwert & Haug (EH) and compare to various limiting cases. We develop a new software package, BRpack, for direct numerical applications. This package uses a combination of pre-computed tables and analytical approximations to efficiently cover a wide range of electron and photon energies, providing a representation of the EH Gaunt factor to better than 0.03% precision for Z<=2. Our results are compared to those of previous studies highlighting the improvements achieved here. BRpack should be useful in computations of spectral distortions of the cosmic microwave background, radiative transfer problems during reionization or inside galaxy clusters, and the modeling of galactic free-free foregrounds. The developed computational methods can furthermore be extended to higher energies and ion charge.

    ↳ astro-ph.COastro-ph.HEhep-phMNRAS(2020)·30 citations
18. 18*

    Time-evolution of net-baryon density fluctuations across the QCD critical region

    Marcus Bluhm🇫🇷 · Marlene Nahrgang (SUBATECH, Nantes & EMMI, Darmstadt)🇫🇷

    We investigate the role of a finite surface tension during the time-evolution of fluctuations in the net-baryon density. The systems in this study undergo a temperature evolution across the phase transition in the critical region of the QCD phase diagram. The occuring non-equilibrium effects are discussed.

    ↳ nucl-thhep-phSpringer Proc.Phys.(2020)·8 citations
19. 19*

    Physics with charmonia at the SPD experiment

    Igor Denisenko🇷🇺

    The $J/\psi$ production is a powerful probe of hadron structure, which is complementary to other parts of the SPD physics program. In this work, the current experimental status and modern theoretical approaches to $J/\psi$ and charmonia production are reviewed. In this context, the SPD performance and feasibility of key measurements are discussed.

    ↳ hep-exhep-phJ.Phys.Conf.Ser.(2020)·0 citations
20. 20*

    A Note on the Swampland Distance Conjecture

    A. Kehagias🇬🇷 · A. Riotto🇨🇭

    We discuss the Swampland Distance Conjecture in the framework of black hole thermodynamics. In particular, we consider black holes in de Sitter space and we show that the Swampland Distance Conjecture is a consequence of the fact that apparent horizons are always inside cosmic event horizons whenever they exist in the case of fast-roll inflation. In addition, we show that the Bekenstein and the Hubble entropy bounds for the entropy in a region of spacetime lead similarly to the same conjecture.

    ↳ hep-thastro-ph.COgr-qchep-phFortsch.Phys.(2020)·10 citations
21. 21*

    Fundamental physics with blazar spectra: a critical appraisal

    Giorgio Galanti🇮🇹 · Fabrizio Tavecchio🇮🇹 · Marco Landoni🇮🇹

    Very-high-energy (VHE) BL Lac spectra extending above $10\mathrm{TeV}$ provide a unique opportunity for testing physics beyond the standard model of elementary particle and alternative blazar emission models. We consider the hadron beam, the photon to axion-like particle (ALP) conversion, and the Lorentz invariance violation (LIV) scenarios by analyzing their consequences and induced modifications to BL Lac spectra. In particular, we consider how different processes can provide similar spectral features (e.g. hard tails) and we discuss the ways they can be disentangled. We use HEGRA data of a high state of Markarian 501 and the HESS spectrum of the extreme BL Lac (EHBL) 1ES 0229+200. In addition, we consider two hypothetical EHBLs similar to 1ES 0229+200 located at redshifts $z=0.3$ and $z=0.5$. We observe that both the hadron beam and the photon-ALP oscillations predict a hard tail extending to energies larger than those possible in the standard scenario. Photon-ALP interaction predicts a peak in the spectra of distant BL Lacs at about $20-30\mathrm{TeV}$, while LIV produces a strong peak in all BL Lac spectra around $\sim 100\mathrm{TeV}$. The peculiar feature of the photon-ALP conversion model is the production of oscillations in the spectral energy distribution, so that its detection/absence can be exploited to distinguish among the considered models. The above mentioned features coming from the three models may be detected by the upcoming Cherenkov Telescope Array (CTA). Thus, future observations of BL Lac spectra could eventually shed light about new physics and alternative blazar emission models, driving fundamental research towards a specific direction.

    ↳ astro-ph.HEhep-phMNRAS(2020)·24 citations
22. 22*

    Neutrino propagation hinders fast pairwise flavor conversions

    Shashank Shalgar🇩🇰 · Ian Padilla-Gay🇩🇰 · Irene Tamborra🇩🇰

    Neutrino flavor conversions may dramatically affect the inner working of compact astrophysical objects as well as the synthesis of the heavier elements. We present the first sophisticated numerical solution of the neutrino flavor conversion within a (2+1+1) dimensional setup: we include the advective term in the neutrino equations of motion and track the flavor evolution in two spatial dimensions, one angular variable, and time. Notably, the advective term hinders the development of neutrino pairwise conversions, if the conditions favoring such conversions (i.e., crossings between the angular distributions of ${\nu }_e$ and ${\bar{\nu }}_e$ or a non-negligible flux of neutrinos traveling backward with respect to the main propagation direction) exist for time scales shorter than the typical time scale of the advective term. As a consequence, fast pairwise conversions can only occur when the conditions favoring flavor conversions are self-sustained and global, such as the ones induced by the lepton emission self-sustained asymmetry (LESA) in core-collapse supernovae. Our work highlights the major impact of the dynamical evolution of the neutrino field on the growth of flavor instabilities and the strong interplay between classical and quantum effects. Critical limitations of the linear stability analysis, used to predict neutrino flavor instabilities, are also pointed out.

    ↳ astro-ph.HEhep-phJCAP(2020)·53 citations
23. 23*

    Searching for Sterile Neutrino with X-ray Intensity Mapping

    A.Caputo🇪🇸 · M. Regis🇮🇹 · M. Taoso🇮🇹

    The cosmological X-ray emission associated to the possible radiative decay of sterile neutrinos is composed by a collection of lines at different energies. For a given mass, each line corresponds to a given redshift. In this work, we cross correlate such line emission with catalogs of galaxies tracing the dark matter distribution at different redshifts. We derive observational prospects by correlating the X-ray sky that will be probed by the eROSITA and Athena missions with current and near future photometric and spectroscopic galaxy surveys. A relevant and unexplored fraction of the parameter space of sterile neutrinos can be probed by this technique.

    ↳ astro-ph.COhep-phJCAP(2020)·37 citations
24. 24*

    The PHQMD model for the formation of nuclear clusters and hypernuclei in heavy-ion collisions

    V. Kireyeu🇷🇺 · J. Aichelin🇫🇷 · E. Bratkovskaya🇩🇪 · A. Le Fèvre🇩🇪 · V. Lenivenko🇷🇺 · V. Kolesnikov🇷🇺 · Y. Leifels🇩🇪 · V. Voronyuk🇷🇺

    Modeling of the process of the formation of nuclear clusters in the hot nuclear matter is a challenging task. We present the novel n-body dynamical transport approach - PHQMD (Parton-Hadron-Quantum-Molecular Dynamics) [1] for the description of heavy-ion collisions as well as clusters and hpernuclei formation. The PHQMD extends well established PHSD (Parton-Hadron-String Dynamics) approach - which incorporates explicit partonic degrees-of-freedom (quarks and gluons), an equation-of-state from lattice QCD, as well as dynamical hadronization and hadronic elastic and inelastic collisions in the final reaction phase, by n-body quantum molecular dynamic propagation of hadrons which allows choosing of the equation of state with different compression modulus. The formation of clusters, including hypernuclei, is realized by incorporation the Simulated Annealing Clusterization Algorithm (SACA). We present first results from PHQMD on the study of the production rates of strange hadrons, nuclear clusters and hypernuclei in e1elementary and heavy-ion collisions at NICA energies. In particular, sensitivity on the "hard" and "soft" equation of state within the PHQMD model was investigated for "bulk" observables.

    ↳ nucl-thhep-phBull.Russ.Acad.Sci.Phys.(2020)·6 citations
25. 25*

    Non-negligible Oscillation Effects in the Crustal Geo-neutrino Calculations

    Ran Han🇨🇳 · Yu-Feng Li🇨🇳 · Xin Mao🇨🇳

    An accurate prediction of the geo-neutrino signal from the crust serves as a necessary prerequisite in the determination of the geo-neutrino flux from the mantle. In this work we report the non-negligible effect associated to the exact three-flavor antineutrino survival probability in the calculation of the crustal geo-neutrino signal, which was usually approximated as a constant average in previous studies. A geo-neutrino signal underestimation of about 1-2 TNU is observed as a result of the oscillatory behaviour within the local crustal region extending for about 300 km from the experimental site. We also estimated that the Mikheyev-Smirnov-Wolfenstein matter oscillation is responsible for a $0.1\%$-$0.3\%$ increase of the local crustal signal, depending on the detector location. This work reminds that the exact oscillation possibility in matter should be considered for future prediction of the local crustal geo-neutrino signal.

    ↳ physics.geo-phastro-ph.EPhep-phPRD(2019)·4 citations
26. 26*

    Equivalence Principle for Antiparticles and its Limitations

    U. D. Jentschura🇺🇸

    We investigate the particle-antiparticle symmetry of the gravitationally coupled Dirac equation, both on the basis of the gravitational central-field problem and in general curved space-time backgrounds. First, we investigate the central-field problem with the help of a Foldy-Wouthuysen transformation. This disentangles the particle from the antiparticle solutions, and leads to a "matching relation" of the inertial and the gravitational mass, which is valid for both particles as well as antiparticles. Second, we supplement this derivation by a general investigation of the behavior of the gravitationally coupled Dirac equation under the discrete symmetry of charge conjugation, which is tantamount to a particle -> antiparticle transformation. Limitations of the Einstein equivalence principle due to quantum fluctuations are discussed. In quantum mechanics, the question of where and when in the Universe an experiment is being performed, can only be answered up to the limitations implied by Heisenberg's Uncertainty Principle, questioning an assumption made in the original formulation of the Einstein equivalence principle. Furthermore, at some level of accuracy, it becomes impossible to separate non-gravitational from gravitational experiments, leading to further limitations.

    ↳ physics.gen-phhep-phInt.J.Mod.Phys.A(2019)·1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.