Wed·Oct 25, 2017Wednesday·October 25, 2017

1. 01*

   't Hooft mechanism, anomalous gauge U(1), and "invisible" axion from string

   Jihn E. Kim🇰🇷

   Among solutions of the strong CP problem, the "invisible" axion in the narrow axion window is argued to be the remaining possibility among natural solutions on the smallness of $\bar{\theta }$. Related to the gravity spoil of global symmetries, some prospective "invisible" axions from theory point of view are discussed. In all these discussions including the observational possibility and cosmological constraints, including a safe domain wall problem, must be included.

   hep-phastro-ph.COhep-th3 citations
2. 02*

   About heavy neutrinos: Lepton-flavor violation in decays of charged leptons

   H. Novales-Sánchez🇲🇽 · M. Salinas🇲🇽 · J. J. Toscano🇲🇽

   The fundamental description of nature, beyond the Standard Model (SM), may include heavy neutrinos that mix and thus allow processes in which lepton flavor is not preserved. We investigate the impact of charged currents that couple heavy gauge bosons to heavy neutrinos and SM leptons on lepton-flavor-violating decays of SM leptons into three charged leptons, with no final-state neutrinos. We implement our expressions for the leading contributions to $\mathrm{Br}(l_{\alpha }\to l_{\beta }{l}_{\sigma }{l}_{\sigma })$, which hold for either Dirac or Majorana neutrinos, to the trilepton decay $\mu \to 3e$, of the muon, and so determine sets of masses of heavy neutrinos and the heavy gauge boson, within GeVs to few TeVs, that are consistent with the upper bounds provided by the SINDRUM Collaboration. We find, however, that constraints dictated by the upper bound on $\mathrm{Br}(\mu \to e\gamma )$, from the MEG Collaboration, are more stringent. We utilize such parameters to find that the contributions to tau decays are $\sim 10^{-15}-10^{-13}$, well below bounds from $B$ factories. The mixing of heavy and SM charged bosons is also investigated. We find that current experimental data from MEG and SINDRUM would allow mixing angles as large as $\sim 10^{-2}$, for a relatively light new charged boson, but the expected sensitivity of the Mu3e experiment would be capable of setting an upper bound on this angle as small as $\sim 10^{-4}$ if the mass of this boson is within the range of few TeVs.

   hep-phJ.Phys.G(2018)·8 citations
3. 03*

   Dark Matter-Neutrino Interaction in Light of Collider and Neutrino Telescope Data

   Reinard Primulando🇮🇩 · Patipan Uttayarat🇹🇭

   We study the DM-neutrino interaction in the framework of simplified model. The phenomenology of such an interaction are derived. We also investigate the bound on DM-neutrino interaction from the LHC and neutrino telescopes. We find that for the case of a scalar dark matter, the LHC gives a stronger bound on dark matter annihilation cross-section than the neutrino telescopes. However, for the fermionic dark matter case the neutrino telescopes bounds are more stringent for dark matter mass, $\gtrsim 200$ MeV. In the case of lower DM mass, the neutrino telescopes provide better bounds for a light mediator, while the collider bounds are better for a heavy mediator. Possible UV completions of the simplified model are briefly discussed.

   hep-phastro-ph.HEhep-exJHEP(2018)·27 citations
4. 04*

   Different production sources of light nuclei in relativistic heavy-ion collisions

   Rui-qin Wang🇨🇳 · Jun Song🇨🇳 · Gang Li🇨🇳 · Feng-lan Shao🇨🇳

   We propose a new method, i.e., an exclusive quark combination model + an inclusive hadron recombination model, to study different production sources of light nuclei in relativistic heavy-ion collisions. We take deuterons and ${}^3$He produced in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV as examples to present contributions of different production sources by studying their rapidity densities $dN/dy$, yield ratios and transverse momentum ($p_T$) spectra just after the hadronization as well as at the final kinetic freeze-out. We find that: only very small fractions of $d$ and ${}^3$He are created just after the hadronization; nucleons from $\Delta$ resonance decays make a much larger contribution to the regeneration of light nuclei at the hadronic phase stage, and this contribution takes about 79\% and 92\% for $d$ and ${}^3$He, respectively, observed at the final kinetic freeze-out. We also find that yield ratios $d/p$, ${}^3$He$/p$ and ${}^3$He$/d$ are good observables to probe contributions for light nuclei from different production sources, and provide a natural explanation for constant values of $d/p$ and ${}^3$He$/p$ as a function of the averaged charged multiplicity measured by the ALICE Collaboration.

   hep-phnucl-thCPC(2019)·10 citations
5. 05*

   Constraining slepton and chargino through compressed top squark search

   Partha Konar🇮🇳 · Tanmoy Mondal🇮🇳 · Abhaya Kumar Swain🇮🇳

   We examine the compressed mass spectrum with sub-TeV top squark ($\tilde{t}$) as lightest colored (s)particle in natural supersymmetry (SUSY). Such spectra are searched along with an additional hard jet, not only to boost the soft decay particles, also to yield enough missing transverse momentum. Several interesting kinematic variables are proposed to improve the probe performance for this difficult region, where we concentrate on relatively clean dileptonic channel of the top squark decaying into lightest neutralino (${\chi }_1^0$), which is also the lightest supersymmetric particle. In this work, we investigate the merit of these kinematic variables, sensitive to compressed mass region extending the search by introducing additional states, chargino and slepton (sneutrino) having masses in between the $\tilde{t}$ and ${\chi }_1^0$. Enhanced production and lack of branching suppression are capable of providing a strong limit on chargino and slepton/sneutrino mass along with top squark mass. We perform a detailed collider analysis using simplified SUSY spectrum and found that with the present LHC data $M_{\tilde{t}}$ can be excluded up to 710 GeV right away for $M_{{\chi }_1^0}$ of 640 GeV for a particular mass gap between different states.

   hep-phhep-exJHEP(2018)·5 citations
6. 06*

   The structure and analytic properties of the scattering amplitude at LHC energies

   Oleg V. Selyugin🇷🇺 · Jean-René Cudell🇧🇪

   Elastic proton-proton scattering is reviewed starting from the results of the LHC experiments conducted by the TOTEM and ATLAS collaborations, and the HEGS model and a simple phenomenological parametrisation are compared with the new data on the differential elastic proton-proton scattering cross section, which detect a non-exponential behaviour of the differential cross sections in the first diffraction cone. We consider the influence of various assumptions on the extraction of the elastic scattering parameters, and on the deduction of the total cross section.

   hep-phhep-ex2 citations
7. 07*

   Saving the Higgs Portal for Singlet Scalar Dark Matter

   Javier Quilis🇪🇸

   The Higgs-portal model with a singlet scalar Dark Matter particle is one of the simplest extensions to the Standard Model that can reproduce the relic density. Unfortunately this model is strongly constrained by direct and indirect DM detection, as well as by collider physics. Most of the parameter space is already ruled-out and the rest will be explored in the next future. We show that a simple extension of the DM sector with a second scalar singlet enables a substantial opening of the allowed window in the parameter space.

   hep-phPoS(2017)·1 citation
8. 08*

   Production of the charmoniumlike state $Y(4220)$ through the $p\bar{p}\to Y(4220){\pi }^0$ reaction

   Jun-Zhang Wang🇨🇳 · Hao Xu🇨🇳 · Ju-Jun Xie🇨🇳 · Xiang Liu🇨🇳

   The $Y(4220)$ production in the process of $p\bar{p}\to Y(4220){\pi }^0$ is studied within the effective Lagrangian approach. We first study the $e^{+}{e}^{-}\to Y(4220)\to p\bar{p}{\pi }^0$ reaction at center-of-mass energy $4.258$ GeV with the assumption that the $Y(4220)$ is a $\psi (4S)$ state. We show that the inclusion of nucleon and nucleon resonance leads to a quite good description of the experimental data of ${\pi }^{0}p$ and ${\pi }^0\bar{p}$ invariant mass distributions. Then, the total and angular distributions of the $p\bar{p}\to Y(4220){\pi }^0$ reaction are investigated. It is shown that the nucleon pole is dominant but the contributions from excited nucleon resonances are non-negligible. The $p\bar{p}\to Y(4220){\pi }^0$ reaction is useful for studying the property of $Y(4220)$ and our calculated results may be tested at the forthcoming $\overline{\text{mbox}P}$ANDA experiments.

   hep-phhep-exPRD(2017)·7 citations
9. 09*

   A two particle hidden sector and the oscillations with photons

   Pedro Diego Alvarez🇨🇱 · Paola Arias🇨🇱 · Carlos Maldonado🇨🇱

   We present a detailed study of the oscillations and optical properties for vacuum, in a model for the dark sector that contains axion-like particles and hidden photons. In this model, both can couple to photons. We provide bounds for the couplings versus the mass, using current results from ALPS-I and PVLAS. We also discuss the challenges for the detection of models with more than one hidden particle in light shining trough wall-like experiments.

   hep-phEPJC(2018)·7 citations
10. 10*

    Lepton flavor (universality) violation in $B$-meson decays

    Olcyr Sumensari🇮🇹

    Even though the LHC searches did not unveil the new physics particles so far, LHCb hints towards deviations from lepton flavor universality in exclusive decays based on the transition $b\to s\ell \ell$. In this proceeding, we present a new leptoquark model that can explain both $R_K^{\exp }<R_K^{\mathrm{SM}}$ and $R_{K^{\ast }}^{\exp }<R_{K^{\ast }}^{\mathrm{SM}}$ via loop effects, consistent with observations made by LHCb. We discuss the main predictions of this scenario that can be tested experimentally, which include the bounds on lepton flavor violating decays $\mathcal{B}(Z\to \mu \tau )\lesssim \mathcal{O}(10^{-7})$ and $\mathcal{B}(B\to K\mu \tau )\lesssim \mathcal{O}(10^{-9})$.

    hep-phPoS(2017)·6 citations
11. 11*

    Quark Pseudo-Distributions at Short Distances

    A. V. Radyushkin🇺🇸

    We perform a one-loop study of the small-$z_3^2$ behavior of the Ioffe-time distribution (ITD) $\mathcal{M}(\nu ,z_3^2)$, the basic function that may be converted into parton pseudo- and quasi-distributions. We calculate the corrections at the operator level, so that our results may be later used for pseudo-distribution amplitudes and generalized parton pseudo-distributions. We separate two sources of the $z_3^2$-dependence at small $z_3^2$. One is related to the ultraviolet (UV) singularities generated by the gauge link, and another to short-distance logarithms generating perturbative evolution of parton densities. Our calculation explicitly shows that, for a finite UV cut-off, the UV-singular terms vanish when $z_3^2=0$. The UV divergences are absent in the ratio $\mathcal{M}(\nu ,z_3^2)/\mathcal{M}(0,z_3^2)$ ("reduced" ITD). Still, it has a non-trivial short-distance behavior due to $\ln z_3^2{\Lambda }^2$ terms generating perturbative evolution of the parton densities. We give an explicit expression, up to constant terms, for the reduced ITD at one loop. It may be used in extraction of PDFs from the lattice QCD simulations. We also use our results to get new insights concerning the structure of parton quasi-distributions at one-loop level.

    hep-phhep-latPLB(2018)·87 citations
12. 12*

    Testing merging of Dark Exotic Stars from Gravitational Waves in the Multi-messenger approach

    Andrea Addazi🇨🇳 · Antonino Marciano🇨🇳

    We discuss possible implications of the recent detection by the LIGO and VIRGO collaboration of the gravitational-wave event GW170817, the signal of which is consistent with predictions in general relativity on the merging of neutron stars. A near-simultaneous and spatially correlated observation of a gamma-ray burst, the GRB 170817A signal, was achieved independently by the Fermi Gamma-ray Burst Monitor, and by the Anti-coincidence Shield for the Spectrometer of the International Gamma-Ray Astrophysics Laboratory. Motivated by this near temporal and spatial concomitance of events, which can occur by chance only with the probability $5.0\times 10^{-8}$, we speculate on the possibility that new dark stars signals could be detected from the LIGO/VIRGO detectors. This proposal, which aims at providing a test for some models of dark matter, relies on the recent achievement of detecting, for visible ordinary matter, the merging of neutron stars both in the gravitational and the electromagnetic channel. A lack of correlation between the two expected signals would suggest a deviation from the properties of ordinary matter. Specifically, we focus on models of invisible dark matter, and in particular we study the case of mirror dark matter, within the framework of which a large amount of mirror neutron stars are naturally envisaged to occupy our dark matter halo. The observation of an electromagnetically hidden event inside the dark matter halo of our galaxy should provide a hint of new physics. There would be indeed no satisfactorily complete explanation accounting for the lack of electromagnetic signal, if only standard neutron star merging were considered to describe events that happen so close to us.

    hep-phgr-qcInt.J.Mod.Phys.A(2018)·5 citations
13. 13*

    Predictions for exclusive Higgs cross sections

    Emanuele Re🇨🇭

    I give an overview of recent theoretical results for exclusive Higgs-production cross sections, focusing in particular on processes where precise predictions will be relevant in the near future.

    hep-ph0 citations
14. 14*

    Correlation of strange particles production with multiplicity in a multi-pomeron exchange model

    G. Feofilov🇷🇺 · V. Kovalenko🇷🇺 · A. Puchkov (Saint Petersburg State University)🇷🇺

    We propose a further development of a multi-pomeron exchange model of pp and p$\bar{p}$ collisions at high energy. The model describes consistently multiplicity, transverse momentum of charged particles and their correlation in wide energy range (from ISR to LHC) by introducing string collectivity effects in pp collisions. The particles species differentiation is implemented according to Schwinger mechanism. Due to the influence of higher resonances on the yields of observed particles, we implement the production of a large set of hadron resonances with cascade decays. We present the results on pion, kaon and proton yields as a function of the collision energy and the correlation of strange and multi-strange hadrons with multiplicity and compare the results with experimental data.

    hep-phnucl-th3 citations
15. 15*

    Tree-level Quartic for a Holographic Composite Higgs

    Csaba Csáki🇺🇸 · Michael Geller🇺🇸 · Ofri Telem🇺🇸

    We present a new class of composite Higgs models where an adjustable tree-level Higgs quartic coupling allows for a significant reduction in the tuning of the Higgs potential. Our 5D warped space implementation is the first example of a holographic composite Higgs model with a tree-level quartic. It is inspired by a 6D model where the quartic originates from the Tr [A_5,A_6]^2 term of the gauge field strength, the same model that led to the original little Higgs construction of Arkani-Hamed, Cohen, and Georgi. Beyond the reduction of the tuning and the standard composite Higgs signatures, the model predicts a doubling of the KK states with relatively small splittings as well as a Higgs sector with two doublets in the decoupling limit.

    hep-phJHEP(2018)·14 citations
16. 16*

    Conformality Lost in Efimov Physics

    Abhishek Mohapatra🇺🇸 · Eric Braaten🇺🇸

    A general mechanism for the loss of conformal invariance is the merger and disappearance of an infrared fixed point and an ultraviolet fixed point of a renormalization group flow. We show explicitly how this mechanism works in the case of identical bosons at unitarity as the spatial dimension $d$ is varied. For $d$ between the critical dimensions $d_1=2.30$ and $d_2=3.76$, there is loss of conformality as evidenced by the Efimov effect in the three-body sector. The beta function for an appropriate three-body coupling is a quadratic polynomial in that coupling. For $d<d_1$ and for $d>d_2$, the beta function has two real roots that correspond to infrared and ultraviolet fixed points. As $d$ approaches $d_1$ from below and as $d$ approaches $d_2$ from above, the fixed points merge and disappear into the complex plane. For $d_1<d<d_2$, the beta function has complex roots and the renormalization group flow for the three-body coupling is a limit cycle.

    ↳ cond-mat.quant-gashep-phnucl-thPRA(2018)·13 citations
17. 17*

    Performance of Complex Langevin Simulation in 0+1 dimensional massive Thirring model at finite density

    Hirotsugu Fujii🇯🇵 · Syo Kamata🇯🇵 · Yoshio Kikukawa🇯🇵

    Statistical sampling with the complex Langevin (CL) equation is applied to (0+1)-dimensional Thirring model, and its uniform-field variant, at finite fermion chemical potential $\mu$. The CL simulation reproduces a crossover behavior which is similar to but actually deviating from the exact solution in the transition region, where we confirm that the CL simulation becomes susceptible to the drift singularities, i.e., zeros of the fermion determinant. In order to simulate the transition region with the CL method correctly, we examine two approaches, a reweighting method and a model deformation, in both of which a single thimble with an attractive fixed point practically covers the integration domain and the CL sampling avoids the determinant zeros. It turns out that these methods can reproduce the correct crossover behavior of the original model with using reference ensembles in the complexified space. However, they need evaluation of the reweighting factor, which scales with the system size exponentially. We discuss feasibility of applying these methods to the Thirring model and to more realistic theories.

    ↳ hep-lathep-ph8 citations
18. 18*

    Hunting magnetic monopoles and more with MoEDAL at the LHC

    Vasiliki A. Mitsou (for the MoEDAL Collaboration)🇪🇸

    The MoEDAL experiment at the LHC is optimised to detect highly-ionising particles such as magnetic monopoles, dyons and (multiply) electrically-charged stable massive particles predicted in a number of theoretical scenarios. MoEDAL, deployed in the LHCb cavern, combines passive nuclear track detectors with magnetic monopole trapping volumes, while backgrounds are being monitored with an array of MediPix detectors. The detector concept and its physics reach is presented with emphasis given to recent results on monopoles.

    ↳ hep-exhep-phphysics.ins-det0 citations
19. 19*

    Wilson loop calculation in QGP using non-supersymmetric AdS/CFT

    Somdeb Chakraborty🇮🇳 · Kuntal Nayek🇮🇳 · Shibaji Roy🇮🇳

    Previously, two of the present authors obtained the decoupling limit and the corresponding throat geometry of non-supersymmetric D3 brane solution of type IIB string theory. In analogy with the supersymmetric case, it describes the gravity dual of a non-supersymmetric gauge theory with QCD-like properties such as running coupling and confinement (or mass gap) in certain range of its parameters. In this paper, we consider a `black' version of the non-supersymmetric D3 brane solution in the decoupling limit and use this gravity background to holographically compute the expectation value of a time-like Wilson loop which, in turn, is related to the potential of a heavy quark-antiquark pair. By boosting the gravity solution along one of the brane directions and placing the pair at an arbitrary orientation with this direction, we numerically obtain the variation of the screening length as well as the potential with velocity, its orientation with respect to the direction of motion and other parameters of the theory. Remarkably enough, our results are in qualitative agreement with those obtained holographically in supersymmetric gauge theories indicating that these features are quite robust and universal as they are insensitive to the presence of any supersymmetry in the theory. The physical interpretations of the variations with respect to the other parameters of the theory, not observed in supersymmetric theory, have also been given.

    ↳ hep-thhep-phnucl-thNPB(2018)·11 citations
20. 20*

    Report by the Committee on the Scientific Case of the ILC Operating at 250 GeV as a Higgs Factory

    Shoji Asai🇯🇵 · Junichi Tanaka🇯🇵 · Yutaka Ushiroda🇯🇵 · Mikihiko Nakao🇯🇵 · Junping Tian🇯🇵 · Shinya Kanemura🇯🇵 · Shigeki Matsumoto🇯🇵 · Satoshi Shirai🇯🇵 · Motoi Endo🇯🇵 · Mitsuru Kakizaki🇯🇵

    This document is the final report by the Committee on the Scientific Case of the ILC Operating at 250 GeV as a Higgs Factory. This committee was commissioned by the Japan Association of High Energy Physicists. The purpose of this committee is to investigate and compare the capability to determine the energy scale of new phenomena and new principles and the capability to uncover the origin of matter-antimatter asymmetry.

    ↳ hep-exhep-ph27 citations
21. 21*

    Oriented polar molecules in a solid inert-gas matrix: a proposed method for measuring the electric dipole moment of the electron

    A.C. Vutha🇨🇦 · M. Horbatsch🇨🇦 · E.A. Hessels🇨🇦

    We propose a very sensitive method for measuring the electric dipole moment of the electron using polar molecules embedded in a cryogenic solid matrix of inert-gas atoms. The polar molecules can be oriented in the $\hat{\mathrm{z}}$ direction by an applied electric field, as has recently been demonstrated by Park, et al. [Angewandte Chemie {\bf 129}, 1066 (2017)]. The trapped molecules are prepared into a state which has its electron spin perpendicular to $\hat{\mathrm{z}}$, and a magnetic field along $\hat{\mathrm{z}}$ causes precession of this spin. An electron electric dipole moment $d_e$ would affect this precession due to the up to 100~GV/cm effective electric field produced by the polar molecule. The large number of polar molecules that can be embedded in a matrix, along with the expected long coherence times for the precession, allows for the possibility of measuring $d_e$ to an accuracy that surpasses current measurements by many orders of magnitude. Because the matrix can inhibit molecular rotations and lock the orientation of the polar molecules, it may not be necessary to have an electric field present during the precession. The proposed technique can be applied using a variety of polar molecules and inert gases, which, along with other experimental variables, should allow for careful study of systematic uncertainties in the measurement.

    ↳ physics.atom-phhep-phAtoms(2018)·59 citations
22. 22*

    Magnetic field in expanding quark-gluon plasma

    Evan Stewart🇺🇸 · Kirill Tuchin🇺🇸

    Intense electromagnetic fields are created in the quark-gluon plasma by the external ultra-relativistic valence charges. The time-evolution and the strength of this field are strongly affected by the electrical conductivity of the plasma. Yet, it has recently been observed that the effect of the magnetic field on the plasma flow is small. We compute the effect of plasma flow on magnetic field and demonstrate that it is less than 10\%. These observations indicate that the plasma hydrodynamics and the dynamics of electromagnetic field decouple. Thus, it is a very good approximation, on the one hand, to study QGP in the background electromagnetic field generated by external sources and, on the other hand, to investigate the dynamics of magnetic field in the background plasma. We also argue that the wake induced by the magnetic field in plasma is negligible.

    ↳ nucl-thhep-phPRC(2018)·33 citations
23. 23*

    Continuum extrapolation of quarkonium correlators at non-zero temperature

    Heng-Tong Ding🇨🇳 · Olaf Kaczmarek🇩🇪 · Anna-Lena Kruse🇩🇪 · Hiroshi Ohno🇺🇸 · Hauke Sandmeyer🇩🇪

    In the investigation of in-medium modifications of quarkonia and for determining heavy quark diffusion coefficients, correlation functions play a crucial role. For the first time we perform a continuum extrapolation of charmonium and bottomonium correlators in the vector channel based on non-perturbatively clover-improved Wilson fermions in quenched lattice QCD. Calculations were done at 4 different lattice spacings, spatial extents between 96 and 192, aspect ratio from 1/6 to 1/2, for 5 temperatures between $T/T_c=0.75$ and $T/T_c=2.2$. We interpolate between different quark masses to match to the same vector meson mass over different lattice setups. Afterwards we extrapolate the renormalized correlators to the continuum. While we find a strong temperature dependence for charmonium, bottomonium states are only slightly affected at higher temperatures.

    ↳ hep-lathep-phEPJ Web Conf.(2018)·8 citations
24. 24*

    The Gravitational Wave Stress-Energy (pseudo)-Tensor in Modified Gravity

    Alexander Saffer🇺🇸 · Nicolas Yunes🇺🇸 · Kent Yagi🇺🇸

    The recent detections of gravitational waves by the advanced LIGO and Virgo detectors open up new tests of modified gravity theories in the strong-field and dynamical, extreme gravity regime. Such tests rely sensitively on the phase evolution of the gravitational waves, which is controlled by the energy-momentum carried by such waves out of the system. We here study four different methods for finding the gravitational wave stress-energy pseudo-tensor in gravity theories with any combination of scalar, vector, or tensor degrees of freedom. These methods rely on the second variation of the action under short-wavelength averaging, the second perturbation of the field equations in the short-wavelength approximation, the construction of an energy complex leading to a Landau-Lifshitz tensor, and the use of Noether's theorem in field theories about a flat background. We apply these methods in General Relativity, scalar-tensor theories and Einstein-Æ{}ther theory to find the gravitational wave stress-energy pseudo-tensor and calculate the rate at which energy and linear momentum is carried away from the system. The stress-energy tensor and the rate of linear momentum loss in Einstein-Æ{}ther theory are presented here for the first time. We find that all methods yield the same rate of energy loss, although the stress-energy pseudo-tensor can be functionally different. We also find that the Noether method yields a stress-energy tensor that is not symmetric or gauge-invariant, and symmetrization via the Belinfante procedure does not fix these problems because this procedure relies on Lorentz invariance, which is spontaneously broken in Einstein-Æ{}ther theory. The methods and results found here will be useful for the calculation of predictions in modified gravity theories that can then be contrasted with observations.

    ↳ gr-qchep-phhep-thClass.Quant.Grav.(2018)·29 citations
25. 25*

    Dilute and dense axion stars

    Luca Visinelli🇸🇪 · Sebastian Baum🇸🇪 · Javier Redondo🇪🇸 · Katherine Freese🇸🇪 · Frank Wilczek🇺🇸

    Axion stars are hypothetical objects formed of axions, obtained as localized and coherently oscillating solutions to their classical equation of motion. Depending on the value of the field amplitude at the core $|{\theta }_0|\equiv |\theta (r=0)|$, the equilibrium of the system arises from the balance of the kinetic pressure and either self-gravity or axion self-interactions. Starting from a general relativistic framework, we obtain the set of equations describing the configuration of the axion star, which we solve as a function of $|{\theta }_0|$. For small $|{\theta }_0|\lesssim 1$, we reproduce results previously obtained in the literature, and we provide arguments for the stability of such configurations in terms of first principles. We compare qualitative analytical results with a numerical calculation. For large amplitudes $|{\theta }_0|\gtrsim 1$, the axion field probes the full non-harmonic QCD chiral potential and the axion star enters the {\it dense} branch. Our numerical solutions show that in this latter regime the axions are relativistic, and that one should not use a single frequency approximation, as previously applied in the literature. We employ a multi-harmonic expansion to solve the relativistic equation for the axion field in the star, and demonstrate that higher modes cannot be neglected in the dense regime. We interpret the solutions in the dense regime as pseudo-breathers, and show that the life-time of such configurations is much smaller than any cosmological time scale.

    ↳ astro-ph.COhep-phPLB(2018)·231 citations
26. 26*

    Effect of reheating on predictions following multiple-field inflation

    Selim C. Hotinli🇬🇧 · Jonathan Frazer🇩🇪 · Andrew H. Jaffe🇬🇧 · Joel Meyers🇨🇦 · Layne C. Price🇺🇸 · Ewan R.M. Tarrant🇬🇧

    We study the sensitivity of cosmological observables to the reheating phase following inflation driven by many scalar fields. We describe a method which allows semi-analytic treatment of the impact of perturbative reheating on cosmological perturbations using the sudden decay approximation. Focusing on $\mathcal{N}$-quadratic inflation, we show how the scalar spectral index and tensor-to-scalar ratio are affected by the rates at which the scalar fields decay into radiation. We find that for certain choices of decay rates, reheating following multiple-field inflation can have a significant impact on the prediction of cosmological observables.

    ↳ astro-ph.COhep-phhep-thPRD(2018)·23 citations
27. 27*

    Quantum scattering beyond the plane-wave approximation

    Dmitry Karlovets🇷🇺

    While a plane-wave approximation in high-energy physics works well in a majority of practical cases, it becomes inapplicable for scattering of the vortex particles carrying orbital angular momentum, of Airy beams, of the so-called Schrödinger cat states, and their generalizations. Such quantum states of photons, electrons and neutrons have been generated experimentally in recent years, opening up new perspectives in quantum optics, electron microscopy, particle physics, and so forth. Here we discuss the non-plane-wave effects in scattering brought about by the novel quantum numbers of these wave packets. For the well-focused electrons of intermediate energies, already available at electron microscopes, the corresponding contribution can surpass that of the radiative corrections. Moreover, collisions of the cat-like superpositions of such focused beams with atoms allow one to probe effects of the quantum interference, which have never played any role in particle scattering.

    ↳ quant-phhep-phJ.Phys.Conf.Ser.(2017)·2 citations
28. 28*

    Preliminary QCD phase transition line for 695 MeV dynamical staggered fermions from effective Polyakov line actions

    Roman Höllwieser🇦🇹 · Jeff Greensite🇺🇸

    We present a phase diagram for SU(3) lattice gauge theory with 695 MeV dynamical staggered fermions, in the plane of temperature and chemical potential, obtained from effective Polyakov line actions. The derivation is via the method of relative weights, and the effective theories are solved at finite chemical potential by mean field theory.

    ↳ hep-lathep-phEPJ Web Conf.(2018)·0 citations
29. 29*

    Modulations in Spectra of Galactic Gamma-ray sources as a result of photon-ALPs mixing

    Jhilik Majumdar🇩🇪 · Francesca Calore🇫🇷 · Dieter Horns🇩🇪

    Axion like particles (ALPs) are fundamental pseudo scalar particles with properties similar to Axions which are a well-known extension of the standard model to solve the strong CP problem in Quantum Chromodynamics. ALPs can oscillate into photons and vice versa in the presence of an external tranversal magnetic field. This oscillation of photon and ALPs could have important implications for astronomical observations, i.e. a characteristic energy dependent attenuation in Gamma ray spectra for astrophysical sources. Here we have revisited the opportunity to search Photon-ALPs coupling in the disappearance channel. We use eight years of Fermi Pass 8 data of a selection of promising galactic Gamma-ray source candidates and study the modulation in the spectra in accordance with Photon-ALPs mixing and estimate best fit values of the parameters i.e. Photon-ALPs coupling constant$(g_{\alpha \gamma \gamma })$ and ALPs mass($m_{\alpha }$). For the magnetic field we use large scale galactic magnetic field models based on Faraday rotation measurements and we have also studied the survival probability of photons in the Galactic plane.

    ↳ astro-ph.HEhep-phJ.Phys.Conf.Ser.(2020)·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.