Fri·Sep 1, 2017Friday·September 1, 2017

1. 01*

   Differential Distributions for t-channel Single Top-Quark Production and Decay at Next-to-Next-to-Leading Order in QCD

   Edmond L. Berger🇺🇸 · Jun Gao🇨🇳 · Hua Xing Zhu🇨🇳

   We present a detailed phenomenological study of the next-to-next-to-leading order (NNLO) QCD corrections for $t$-channel single top (anti-)quark production and its semi-leptonic decay at the CERN Large Hadron Collider (LHC). We find the NNLO corrections for the total inclusive rates at the LHC with different center of mass energies are generally smaller than the NLO corrections, indicative of improved convergence. However, they can be large for differential distributions, reaching a level of $10\%$ or more in certain regions of the transverse momentum distributions of the top (anti-)quark and the pseudo-rapidity distributions of the leading jet in the event. In all cases the perturbative hard scale uncertainties are greatly reduced after the NNLO corrections are included. We also show a comparison of the normalized parton-level distributions to recent data from the 8 TeV measurement of the ATLAS Collaboration. The NNLO corrections tend to shift the theoretical predictions closer to the measured transverse momentum distribution of the top (anti)-quark. Importantly, for the LHC at 13 TeV, we present NNLO cross sections in a fiducial volume with decays of the top quark included.

   hep-phhep-exJHEP(2017)·86 citations
2. 02*

   Multi-Higgs doublet models: physical parametrization, sum rules and unitarity bounds

   Miguel P. Bento🇵🇹 · Howard E. Haber🇺🇸 · J. C. Romão🇵🇹 · João P. Silva🇵🇹

   If the scalar sector of the Standard Model is non-minimal, one might expect multiple generations of the hypercharge-1/2 scalar doublet analogous to the generational structure of the fermions. In this work, we examine the structure of a Higgs sector consisting of N Higgs doublets (where N \geq 2). It is particularly convenient to work in the so-called charged Higgs basis, in which the neutral Higgs vacuum expectation value resides entirely in the first Higgs doublet, and the charged components of remaining N-1 Higgs doublets are mass-eigenstate fields. We elucidate the interactions of the gauge bosons with the physical Higgs scalars and the Goldstone bosons and show that they are determined by an Nx2N matrix. This matrix depends on (N-1)(2N-1) real parameters that are associated with the mixing of the neutral Higgs fields in the charged Higgs basis. Among these parameters, N-1 are unphysical (and can be removed by rephasing the physical charged Higgs fields), and the remaining 2(N-1)^2 parameters are physical. We also demonstrate a particularly simple form for the cubic interaction and some of the quartic interactions of the Goldstone bosons with the physical Higgs scalars. These results are applied in the derivation of Higgs coupling sum rules and tree-level unitarity bounds that restrict the size of the quartic scalar couplings. In particular, new applications to three Higgs doublet models with an order-4 CP symmetry and with a Z_3 symmetry, respectively, are presented.

   hep-phJHEP(2017)·66 citations
3. 03*

   Ensemble-mean ${\mathbf{p}}_{\mathbf{t}}$ and hadron production in high-energy nuclear collisions

   Thomas A. Trainor🇺🇸

   A two-component (soft + hard) model (TCM) of hadron production in high-energy nuclear collisions is applied to ensemble-mean $p_t$ (denoted by ${\bar{p}}_t$) data for $p$-$p$, $p$-Pb and Pb-Pb collisions from the relativistic heavy ion collider (RHIC) and large hadron collider (LHC). This ${\bar{p}}_t$ TCM is directly related to a recently-published TCM for the charge-multiplicity $n_{ch}$ and collision-energy dependence of $p_t$ spectrum data from $p$-$p$ collisions. Multiplicity dependence of the $p$-$p$ spectrum hard component observed in the previous study is consistent with similar behavior for ${\bar{p}}_t$ hard component ${\bar{p}}_{th}$. $p$-$p$ ${\bar{p}}_t$ $n_{ch}$ dependence is observed to follow a noneikonal trend for the TCM hard component (dijet production $\propto n_{ch}^2$), whereas the trend for Pb-Pb collisions is consistent with the eikonal approximation assumed for the Glauber A-A centrality model. The $p$-Pb trend is intermediate, transitioning from the noneikonal $p$-$p$ trend for more-peripheral collisions to an eikonal trend for more-central collisions. The multiplicity dependence of participant number $N_{part}$ and binary-collision number $N_{bin}$ inferred from $p$-Pb ${\bar{p}}_t$ data differs strongly from a Glauber Monte Carlo model of that system. The rapid increase with $n_{ch}$ and large magnitude of ${\bar{p}}_t$ for the $p$-$p$ and $p$-Pb systems suggests that minimum-bias jets (TCM hard component) dominate ${\bar{p}}_t$ variation. The trend for ${\bar{p}}_{th}$ in Pb-Pb collisions is consistent with quantitative modification of jet formation in more-central A-A collisions.

   hep-ph22 citations
4. 04*

   The reactor antineutrino anomaly and low energy threshold neutrino experiments

   B. C. Cañas🇲🇽 · E. A. Garcés🇲🇽 · O. G. Miranda🇲🇽 · A. Parada🇨🇴

   Short distance reactor antineutrino experiments measure an antineutrino spectrum a few percent lower than expected from theoretical predictions. In this work we study the potential of low energy threshold reactor experiments in the context of a light sterile neutrino signal. We discuss the perspectives of the recently detected coherent elastic neutrino-nucleus scattering in future reactor antineutrino experiments. We find that the expectations to improve the current constraints on the mixing with sterile neutrinos are promising. We also analyse the measurements of antineutrino scattering off electrons from short distance reactor experiments. In this case, the statistics is not competitive with inverse beta decay experiments, although future experiments might play a role when compare it with the Gallium anomaly.

   hep-phhep-exPLB(2018)·35 citations
5. 05*

   Neutrinos in Large Extra Dimensions and Short-Baseline ${\nu }_e$ Appearance

   Marcela Carena🇺🇸 · Ying-Ying Li🇨🇳 · Camila S. Machado🇧🇷 · Pedro A. N. Machado🇺🇸 · Carlos E. M. Wagner🇺🇸

   We show that, in the presence of bulk masses, sterile neutrinos propagating in large extra dimensions (LED) can induce electron-neutrino appearance effects. This is in contrast to what happens in the standard LED scenario and hence LED models with explicit bulk masses have the potential to address the MiniBooNE and LSND appearance results, as well as the reactor and Gallium anomalies. A special feature in our scenario is that the mixing of the first KK modes to active neutrinos can be suppressed, making the contribution of heavier sterile neutrinos to oscillations relatively more important. We study the implications of this neutrino mass generation mechanism for current and future neutrino oscillation experiments, and show that the Short-Baseline Neutrino Program at Fermilab will be able to efficiently probe such a scenario. In addition, this framework leads to massive Dirac neutrinos and thus precludes any signal in neutrinoless double beta decay experiments.

   hep-phPRD(2017)·72 citations
6. 06*

   Study of $B_c$ decays into charmonia and $D$ mesons

   Stanislav Dubnicka🇸🇰 · Anna Z. Dubnickova🇸🇰 · Aidos Issadykov🇷🇺 · Mikhail A. Ivanov🇷🇺 · Andrej Liptaj🇸🇰

   In the wake of recent measurements of the decays $B_c^{+}\to J/\psi D_s^{+}$ and $B_c^{+}\to J/\psi D_s^{\ast +}$ performed by the LHCb and ATLAS Collaborations, we recalculate their branching fractions in the framework of the covariant confined quark model. We compare the obtained results with available experimental data, our previous findings and numbers from other approaches.

   hep-phPRD(2017)·33 citations
7. 07*

   Using leptons $p_T$ measurements to constrain $Z^{\prime }$-bosons widths in Drell-Yan processes at the LHC

   Elena Accomando🇬🇧 · Juri Fiaschi🇬🇧 · Stefano Moretti🇬🇧 · Claire H. Shepherd-Themistocleous🇬🇧

   We recognise the appearance of a Focus Point (FP) in the transverse momentum distribution of either leptons originating from a BSM $Z^{\prime }$-boson decay, after a simple normalisation procedure. Exploring the properties of the FP we will be able to define in a general way a new observable, the Focus Point Asymmetry ($A_{\mathrm{FP}}$), which can be used to set constrains on the $Z^{\prime }$ width. We discuss the potential and the sensitivity of the $A_{\mathrm{FP}}$ in as diagnostic tool for $Z^{\prime }$ physics, considering various $Z^{\prime }$ phenomenological realisations.

   hep-ph0 citations
8. 08*

   Top-quark pair production at NNLO QCD and NLO EW accuracy

   Davide Pagani🇩🇪

   We present phenomenological predictions at NNLO QCD and NLO EW accuracy for $t\bar{t}$ distributions at the LHC (8 and 13 TeV). We discuss the impact of the electroweak corrections and quantify the theory errors from scale and PDF uncertainties. Moreover, we show the relevance of a precise determination of the photon PDF for $t\bar{t}$ distributions.

   hep-phhep-ex0 citations
9. 09*

   Off-Diagonal Dark-Matter Phenomenology: Exploring Enhanced Complementarity Relations in Non-Minimal Dark Sectors

   Keith R. Dienes🇺🇸 · Jason Kumar🇺🇸 · Brooks Thomas🇺🇸 · David Yaylali🇺🇸

   In most multi-component dark-matter scenarios, two classes of processes generically contribute to event rates at experiments capable of probing the nature of the dark sector. The first class consists of "diagonal" processes involving only a single species of dark-matter particle -- processes analogous to those which arise in single-component dark-matter scenarios. By contrast, the second class consists of "off-diagonal" processes involving dark-matter particles of different species. Such processes include inelastic scattering at direct-detection experiments, asymmetric production at colliders, dark-matter co-annihilation, and certain kinds of dark-matter decay. In typical multi-component scenarios, the contributions from diagonal processes dominate over those from off-diagonal processes. Unfortunately, this tends to mask those features which are most sensitive to the multi-component nature of the dark sector. In this paper, by contrast, we point out that there exist natural, multi-component dark-sector scenarios in which the off-diagonal contributions actually dominate over the diagonal. This then gives rise to a new, enhanced picture of dark-matter complementarity. In this paper, we introduce a scenario in which this situation arises and examine the enhanced picture of dark-matter complementarity which emerges.

   hep-phastro-ph.COPRD(2017)·18 citations
10. 10*

    Exact one-loop results for $l_i\to l_j\gamma$ in 3-3-1 models

    L.T. Hue🇻🇳 · L.D. Ninh🇻🇳 · T.T. Thuc🇻🇳 · N.T.T. Dat🇮🇹

    We investigate the decays $l_i\to l_j\gamma$, with $l_i=e,\mu ,\tau$ in a general class of 3-3-1 models with heavy exotic leptons with arbitrary electric charges. We present full and exact analytical results keeping external lepton masses. As a by product, we perform numerical comparisons between exact results and approximate ones where the external lepton masses are neglected. As expected, we found that branching fractions can reach the current experimental limits if mixings and mass differences of the exotic leptons are large enough. We also found unexpectedly that, depending on the parameter values, there can be huge destructive interference between the gauge and Higgs contributions when the gauge bosons connecting the Standard Model leptons to the exotic leptons are light enough. This mechanism should be taken into account when using experimental constraints on the branching fractions to exclude the parameter space of the model.

    hep-phEPJC(2018)·53 citations
11. 11*

    Atomki anomaly and the Secluded Dark Sector

    Yasuhiro Yamamoto🇰🇷

    The Atomiki anomaly can be interpreted as a new light vector boson. If such a new particle exists, it could be a mediator between the Standard Model sector and the dark sector including the dark matter. We discussed some simple effective models with these particles. In the models, the secluded dark matter models are good candidates to satisfy the thermal relic abundance. In particular, we found that the dark matter self-interaction can be large enough to solve the small scale structure puzzles if the dark matter is a fermion.

    hep-phEPJ Web Conf.(2018)·9 citations
12. 12*

    Photon-photon and photon-hadron processes in Pythia 8

    Ilkka Helenius🇩🇪

    We present a new implementation of photoproduction processes in e+e- and ep collisions into Pythia 8 Monte-Carlo event-generator. In particular we discuss how the parton showers and multiparton interactions are generated with a resolved photon beam and what is the relative contribution from direct processes in different kinematical regions. As an application we show comparisons to data for charged-particle production in e+e- and ep collisions at LEP and HERA. We consider also photoproduction of dijets comparing to data for ep collisions at HERA and discuss about possibility to further constrain nuclear PDFs with ultra-peripheral heavy-ion collisions at the LHC.

    hep-phCERN Proc.(2018)·17 citations
13. 13*

    Reduced Theoretical Error for QED Tests with 4He+ Spectroscopy

    C.P. Burgess🇨🇦 · P. Hayman🇨🇦 · Markus Rummel🇨🇦 · Laszlo Zalavari🇨🇦

    We apply point-particle effective field theory (PPEFT) to electronic and muonic 4He+ ions, and use it to identify linear combinations of spectroscopic measurements for which the theoretical uncertainties are much smaller than for any particular energy levels. The error is reduced because these combinations are independent of all short-range physics effects up to a given order in the expansion in the small parameters R/a_B and(Z alpha) (where R and a_B are the ion's nuclear and Bohr radii). In particular, the theory error is not limited by the precision with which nuclear matrix elements can be computed, or compromised by the existence of any novel short-range interactions, should these exist. These combinations of 4He+ measurements therefore provide particularly precise tests of QED. The restriction to 4He+ arises because our analysis assumes a spherically symmetric nucleus, but the argument used is more general and extendable to both nuclei with spin, and to higher orders in R/a_B and (Z alpha).

    hep-phhep-thphysics.atom-phPRA(2018)·15 citations
14. 14*

    On the search for the electric dipole moment of strange and charm baryons at LHC and parity violating (P) and time reversal (T) invariance violating spin rotation and dichroism in crystal

    V.G. Baryshevsky🇧🇾

    In a bent crystal the $P$-odd effect of short-lived baryon spin rotation could imitate spin rotation caused by assumed EDM. Use of different behavior of $P$-odd and $T$-odd spin rotations at crystal turning around the direction of particle momentum makes it possible to exclude $P$-odd rotation contribution, when measuring short-lived baryons EDM. Subtraction of the measurement results for angle ranges $\phi$ and $\phi +\pi$ from each other enables measuring $T$-odd rotation at scattering of negatively charged beauty and neutral baryons by axes of unbent crystal.

    hep-ph7 citations
15. 15*

    Cobimaximal lepton mixing from soft symmetry breaking

    W. Grimus🇦🇹 · L. Lavoura🇵🇹

    Cobimaximal lepton mixing, i.e. ${\theta }_{23}=45^{\circ }$ and $\delta =\pm 90^{\circ }$ in the lepton mixing matrix $V$, arises as a consequence of $SV=V^{\ast }\mathcal{P}$, where $S$ is the permutation matrix that interchanges the second and third rows of $V$ and $\mathcal{P}$ is a diagonal matrix of phase factors. We prove that any such $V$ may be written in the form $V=URP$, where $U$ is any predefined unitary matrix satisfying $SU=U^{\ast }$, $R$ is an orthogonal, i.e. real, matrix, and $P$ is a diagonal matrix satisfying $P^2=\mathcal{P}$. Using this theorem, we demonstrate the equivalence of two ways of constructing models for cobimaximal mixing---one way that uses a standard $CP$ symmetry and a different way that uses a $CP$ symmetry including $\mu$--$\tau$ interchange. We also present two simple seesaw models to illustrate this equivalence; those models have, in addition to the $CP$ symmetry, flavour symmetries broken softly by the Majorana mass terms of the right-handed neutrino singlets. Since each of the two models needs four scalar doublets, we investigate how to accommodate the Standard Model Higgs particle in them.

    hep-phPLB(2017)·21 citations
16. 16*

    From the $\gamma \gamma \to p\bar{p}$ reaction to the production of $p\bar{p}$ pairs in ultraperipheral ultrarelativistic heavy-ion collisions at the LHC

    Mariola Kłusek-Gawenda🇵🇱 · Piotr Lebiedowicz🇵🇱 · Otto Nachtmann🇩🇪 · Antoni Szczurek🇵🇱

    In this paper we consider the production of proton-antiproton pairs in two-photon interactions in electron-positron and heavy-ion collisions. We try to understand the dependence of the total cross section on the photon-photon c.m. energy as well as corresponding angular distributions measured by the Belle Collaboration for the $\gamma \gamma \to p\bar{p}$ process. To understand the Belle data we include the proton-exchange, the $f_2(1270)$ and $f_2(1950)$ $s$-channel exchanges, as well as the hand-bag mechanism. The helicity amplitudes for the $\gamma \gamma \to f_2\to p\bar{p}$ process are written explicitly based on a Lagrangian approach. The parameters of vertex form factors are adjusted to the Belle data. Having described the angular distributions for the $\gamma \gamma \to p\bar{p}$ process we present first predictions for the ultraperipheral, ultrarelativistic, heavy-ion reaction ${}^{208}Pb{}^{208}Pb\to$ ${}^{208}Pb{}^{208}Pbp\bar{p}$. Both, the total cross section and several differential distributions for experimental cuts corresponding to the ALICE, ATLAS, CMS, and LHCb experiments are presented. We find the total cross section 100 $\mu$b for the ALICE cuts, 160 $\mu$b for the ATLAS cuts, 500 $\mu$b for the CMS cuts, and 104 $\mu$b taking into account the LHCb cuts. This opens a possibility to study the $\gamma \gamma \to p\bar{p}$ process at the LHC.

    hep-phPRD(2017)·30 citations
17. 17*

    Precision constraints on the top-quark effective field theory at future lepton colliders

    Gauthier Durieux🇩🇪

    We examine the constraints that future lepton colliders would impose on the effective field theory describing modifications of top-quark interactions beyond the standard model, through measurements of the $e^{+}{e}^{-}\to b{W}^{+}\bar{b}{W}^{-}$ process. Statistically optimal observables are exploited to constrain simultaneously and efficiently all relevant operators. Their constraining power is sufficient for quadratic effective-field-theory contributions to have negligible impact on limits which are therefore basis independent. This is contrasted with the measurements of cross sections and forward-backward asymmetries. An overall measure of constraints strength, the global determinant parameter, is used to determine which run parameters impose the strongest restriction on the multidimensional effective-field-theory parameter space.

    hep-phhep-exPoS(2018)·4 citations
18. 18*

    Revised constraints and Belle II sensitivity for visible and invisible axion-like particles

    Matthew J. Dolan🇦🇺 · Torben Ferber🇨🇦 · Christopher Hearty🇨🇦 · Felix Kahlhoefer🇩🇪 · Kai Schmidt-Hoberg🇩🇪

    Light pseudoscalars interacting pre-dominantly with Standard Model gauge bosons (so-called axion-like particles or ALPs) occur frequently in extensions of the Standard Model. In this work we review and update existing constraints on ALPs in the keV to GeV mass region from colliders, beam dump experiments and astrophysics. We furthermore provide a detailed calculation of the expected sensitivity of Belle II, which can search for visibly and invisibly decaying ALPs, as well as long-lived ALPs. The Belle II sensitivity is found to be substantially better than previously estimated, covering wide ranges of relevant parameter space. In particular, Belle II can explore an interesting class of dark matter models, in which ALPs mediate the interactions between the Standard Model and dark matter. In these models, the relic abundance can be set via resonant freeze-out, leading to a highly predictive scenario consistent with all existing constraints but testable with single-photon searches at Belle II in the near future.

    hep-phhep-exJHEP(2017)·358 citations
19. 19*

    Charged Lepton Flavour Violation: An Experimental and Theoretical Introduction

    Lorenzo Calibbi🇨🇳 · Giovanni Signorelli🇮🇹

    Charged lepton flavour violating transitions would be a clear signal of new physics beyond the Standard Model. Their search has been carried out in a variety of channels, the most sensitive being those involving a muon: however no positive evidence has been found so far. The MEG experiment has recently set the best limit on such processes by investigating the existence of the $\mu \to e\gamma$ decay. In the next decade several experiments are planned to pursue the search for $\mu \to e\gamma$, $\mu \to eee$, $\mu \to e$ conversion in nuclei, as well as on processes involving the $\tau$, to an unprecedented level of precision. In this review we want to give a pedagogical introduction on the theoretical motivations for such searches as well as on the experimental aspects upon which they are based.

    hep-phhep-exRiv.Nuovo Cim.(2018)·405 citations
20. 20*

    Multiparton pp and pA collisions -- from geometry to parton-- parton correlations

    B. Blok🇮🇱 · M. Strikman🇺🇸

    We derive expressions for the cross section of the multiparton interactions based on the analysis of the relevant Feynman diagrams. We express the cross sections through the double (triple, ...) generalized parton distributions (GPDs). In the mean field approximation for the double GPDs the answer is expressed through the integral over two gluon form factor which was measured in the exclusive DIS vector meson production.We explain under what conditions the derived expressions correspond to an intuitive picture of hard interactions in the impact parameter representation. The mean field approximation in which correlations of the partons are neglected fail to explain the data, while pQCD induced correlation enhance large $p_{\perp }$ and $0.001<x<0.1$ typically enhance the cross section by a factor of 1.5 -- 2 explaining the current data. We argue that in the small x kinematics ($10^{-4}\le x\le 10^{-3}$) where effects of perturbative correlations diminish, the nonperturbative mechanism kicks in and generates positive correlations comparable in magnitude with the perturbative ones. We explain how our technique can be used for calculations of MPI in the proton - nucleus scattering. The interplay of hard interactions and underlying event is discussed, as well as different geometric pictures for each of MPI mechanisms-pQCD, nonperturbative correlations and mean field. Predictions for value of \effs for various processes and a wide range of kinematics are given. We show that together different MPI mechanisms give good description of experimental data, both at Tvatron, and LHC, including the central kinematics studied by ATLAS and CMS detectors, and forward (heavy flavors) kinematics studied by LHCb.

    hep-phhep-exAdv.Ser.Direct.High Energy Phys.(2018)·31 citations
21. 21*

    Interacting Dark Sector and Precision Cosmology

    Manuel A. Buen-Abad🇺🇸 · Martin Schmaltz🇺🇸 · Julien Lesgourgues🇩🇪 · Thejs Brinckmann🇩🇪

    We consider a recently proposed model in which dark matter interacts with a thermal background of dark radiation. Dark radiation consists of relativistic degrees of freedom which allow larger values of the expansion rate of the universe today to be consistent with CMB data ($H_0$-problem). Scattering between dark matter and radiation suppresses the matter power spectrum at small scales and can explain the apparent discrepancies between $\Lambda$CDM predictions of the matter power spectrum and direct measurements of Large Scale Structure LSS (${\sigma }_8$-problem). We go beyond previous work in two ways: 1. we enlarge the parameter space of our previous model and allow for an arbitrary fraction of the dark matter to be interacting and 2. we update the data sets used in our fits, most importantly we include LSS data with full $k$-dependence to explore the sensitivity of current data to the shape of the matter power spectrum. We find that LSS data prefer models with overall suppressed matter clustering due to dark matter - dark radiation interactions over $\Lambda$CDM at 3-4 $\sigma$. However recent weak lensing measurements of the power spectrum are not yet precise enough to clearly distinguish two limits of the model with different predicted shapes for the linear matter power spectrum. In two Appendices we give a derivation of the coupled dark matter and dark radiation perturbation equations from the Boltzmann equation in order to clarify a confusion in the recent literature, and we derive analytic approximations to the solutions of the perturbation equations in the two physically interesting limits of all dark matter weakly interacting or a small fraction of dark matter strongly interacting.

    ↳ astro-ph.COhep-phJCAP(2018)·191 citations
22. 22*

    Temperature effects on nuclear pseudospin symmetry in the Dirac-Hartree-Bogoliubov formalism

    R. Lisboa🇧🇷 · P. Alberto🇵🇹 · B. V. Carlson🇧🇷 · M. Malheiro🇧🇷

    We present finite temperature Dirac-Hartree-Bogoliubov (FTDHB) calculations for the tin isotope chain to study the dependence of pseudospin on the nuclear temperature. In the FTDHB calculation, the density dependence of the self-consistent relativistic mean fields, the pairing, and the vapor phase that takes into account the unbound nucleon states are considered self-consistently. The mean field potentials obtained in the FTDHB calculations are fit by Woods-Saxon (WS) potentials to examine how the WS parameters are related to the energy splitting of the pseudospin pairs as the temperature increases. We find that the nuclear potential surface diffuseness is the main driver for the pseudospin splittings and that it increases as the temperature grows. We conclude that pseudospin symmetry is better realized when the nuclear temperature increases. The results confirm the findings of previous works using RMF theory at $T=0$, namely that the correlation between the pseudospin splitting and the parameters of the Woods-Saxon potentials implies that pseudospin symmetry is a dynamical symmetry in nuclei. We show that the dynamical nature of the pseudospin symmetry remains when the temperature is considered in a realistic calculation of the tin isotopes, such as that of the Dirac-Hartree-Bogoliubov formalism.

    ↳ nucl-thhep-phPRC(2017)·5 citations
23. 23*

    A hypothetical effect of the Maxwell-Proca electromagnetic stresses on galaxy rotation curves

    Dmitri D. Ryutov🇩🇪 · Dmitry Budker🇩🇪 · Victor V. Flambaum🇦🇺

    The Maxwell-Proca electrodynamics corresponding to a finite photon mass causes a substantial change of the Maxwell stress tensor and, under certain circumstances, may cause the electromagnetic stresses to act effectively as "negative pressure." The paper describes a model where this negative pressure imitates gravitational pull and may produce forces comparable to gravity and even become dominant. The effect is associated with the random magnetic fields in the galactic disk with a scale exceeding the photon Compton wavelength. The presence of a weaker regular field does not affect the forces under consideration. The stresses act predominantly on the interstellar gas and cause an additional force pulling the gas towards the center and towards the galactic plane. The stars do not experience any significant direct force but get involved in this process via a "recycling loop" where rapidly evolving massive stars are formed from the gas undergoing galactic rotation and then lose their masses back to the gas within a time shorter than roughly 1/6 of the rotation period. This makes their dynamics inseparable from that of the rotating gas. The lighter, slowly evolving stars, as soon as they are formed, lose connection to the gas and are confined within the galaxy only gravitationally. Numerical examples based on the parameters of our galaxy reveal both opportunities and challenges of this model and motivate further analysis. The critical issue is the plausibility of formation of the irregular magnetic field that would be force free. Another challenge is developing a predictive model of the evolution of the gaseous and stellar population of the galaxy under the aforementioned scenario. It may be interesting to also explore possible broader cosmological implications of the negative-pressure model.

    ↳ astro-ph.GAhep-phphysics.plasm-phApJ(2019)·11 citations
24. 24*

    Isovector properties of quark matter and quark stars in an isospin-dependent confining model

    Peng-Cheng Chu🇨🇳 · Lie-Wen Chen🇨🇳

    The confining quark matter (CQM) model, in which the confinement and asymptotic freedom are modeled via the Richardson potential for quark-quark vector interaction and the chiral symmetry restoration at high density is described by the density dependent quark mass, is extended to include isospin dependence of the quark mass. Within this extended isospin-dependent confining quark matter (ICQM) model, we study the properties of strange quark matter and quark stars. We find that including isospin dependence of the quark mass can significantly influence the quark matter symmetry energy, the stability of strange quark matter and the mass-radius relation of quark stars. In particular, we demonstrate although the recently discovered large mass pulsars PSR J1614.2230 and PSR J0348+0432 with masses around two times solar mass ($2M_{\odot }$) cannot be quark stars within the original CQM model, they can be well described by quark stars in the ICQM model if the isospin dependence of quark mass is strong enough so that the quark matter symmetry energy is about four times that of a free quark gas. We also discuss the effects of the density dependence of quark mass on the properties of quark stars. Our results indicate that the heavy quark stars with mass around $2M_{\odot }$ (if exist) can put strong constraints on isospin and density dependence of the quark mass as well as the quark matter symmetry energy.

    ↳ nucl-thhep-phPRD(2017)·36 citations
25. 25*

    When Does the Inflaton Decay?

    C. Armendariz-Picon🇺🇸

    In order for the inflaton to decay into radiation at the end of inflation, it needs to couple to light matter fields. In this article we determine whether such couplings cause the inflaton to decay during inflation rather than after it. We calculate decay amplitudes during inflation, and determine to what extent such processes have an impact on the mean and variance of the inflaton, as well as on the expected energy density of its decay products. Although the exponential growth of the decay amplitudes with the number of e-folds appears to indicate the rapid decay of the inflaton, cancellations among different amplitudes and probabilities result in corrections to the different expectation values that only grow substantially when the number of e-folds is much larger than the inverse squared inflaton mass in units of the Hubble scale. Otherwise, for typical parameter choices, it is safe to assume that the inflaton does not decay during inflation.

    ↳ hep-thastro-ph.COhep-phJCAP(2018)·4 citations

* 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.