Fri·Apr 12, 2019Friday·April 12, 2019

1. 01*

   Non-static Analysis of the Anomalous Chiral Conductivities

   Miklos Horvath🇨🇳 · Defu Hou🇨🇳 · Hai-cang Ren🇺🇸

   Given the intrinsic nonequilibrium nature of high-energy collisions the investigation of the dynamical properties of transport phenomena is important. The study of the real-time behavior of various conductivities and susceptibilities help refine the simulation tools we use to compare the theories and the experimental findings. In this contribution we take steps to give the chiral magnetic conductivity in case of magnetic field and chiral imbalance are both space-time dependent. Using linear response approximation we present the general 1-loop resummed expression for the electric current. We also suggest simple limiting cases in hope for possible implementation into a hydrodynamical framework.

   hep-phnucl-thJPS Conf.Proc.(2019)·0 citations
2. 02*

   Several Problems in Particle Physics and Cosmology Solved in One SMASH

   Guillermo Ballesteros🇪🇸 · Javier Redondo🇪🇸 · Andreas Ringwald🇩🇪 · Carlos Tamarit🇩🇪

   The Standard Model (SM) of particle physics is a big success. However, it lacks explanations for cosmic inflation, the matter-anti-matter asymmetry of the Universe, dark matter, neutrino oscillations, and the feebleness of CP violation in the strong interactions. The latter may be explained by a complex scalar field charged under a spontaneously broken global U(1) Peccei-Quinn (PQ) symmetry. Moreover, the pseudo Nambu-Goldstone boson of this breaking -- the axion -- may play the role of the dark matter. Furthermore, the modulus of the PQ field is a candidate for driving inflation. If additionally three extra SM singlet neutrinos (whose mass is induced by the PQ field) are included, the five aforementioned problems can be addressed at once. We review the SM extension dubbed SMASH -for SM-Axion-Seesaw-Higgs portal inflation-, discuss its predictions and tests in astrophysics, cosmology, and laboratory experiments. Variants of SMASH are also considered and commented on.

   hep-phastro-ph.COhep-exhep-thFront.Astron.Space Sci.(2019)·36 citations
3. 03*

   CP symmetry violation in the scalar sector of 331 models

   Camilo A. Rojas🇨🇴 · F. Ochoa🇨🇴 · R. Martinez🇨🇴

   In order to understand some frameworks for CP Violation scenarios in the scalar sector, a 331 model was considered which its main property is the incorporation of a local group symmetry SU(3) in the electroweak sector. In particular, a 331 model with a particular choice of free parameter. CP Violation scenarios were obtained by introducing a discrete symmetry in the scalar triplets, which exhibit a spontaneous CP Violation frame with just one independent CP phase associated. Mass state rotations were obtained.

   hep-phhep-th1 citation
4. 04*

   Status and prospects of `bi-large' leptonic mixing

   Gui-Jun Ding🇨🇳 · Newton Nath🇨🇳 · Rahul Srivastava🇪🇸 · José W. F. Valle🇪🇸

   Bi-large patterns for the leptonic mixing matrix are confronted with current neutrino oscillation data. We analyse the status of these patterns and determine, through realistic simulations, the potential of upcoming long-baseline experiment DUNE in testing bi-large \emph{ansatze} and discriminating amongst them.

   hep-phhep-exPLB(2019)·13 citations
5. 05*

   Top-quark electroweak interactions at high energy

   Fabio Maltoni🇧🇪 · Luca Mantani🇧🇪 · Ken Mimasu🇧🇪

   Modified interactions in the electroweak sector may lead to scattering amplitudes that grow with energy compared to their Standard Model (SM) counterparts. We present a detailed study of all $2\to 2$ scattering amplitudes involving at least one top quark and a pair of EW bosons. We analyse the high energy behaviour of the amplitudes using the Standard Model Effective Field Theory (SMEFT) to parametrise the departures from the SM. We discuss the origin of the energy growth that arise from effective contact interactions by appealing to the Goldstone equivalence theorem and find that the amplitudes obey expected patterns of (non-)interference. The results are connected to unitary-violating behaviour in the framework of anomalous SM interactions. Therein, we identify the appearance of additional growth due to the violation of $SU(2)$ gauge symmetry that leads to substantial differences between the SMEFT and the anomalous couplings approaches. We also discuss the embeddings of the scattering amplitudes into physical collider processes, presenting the parametric SMEFT sensitivity to relevant top quark operators and paying special attention to the extent to which the high energy behaviour of the $2\to 2$ amplitude is retained in the actual processes accessible at colliders. The effective $W$ approximation is exploited to gain analytical insight into the embeddings of the $2\to 2$ helicity amplitudes. Finally, we provide a compendium of processes detailing numerous directions in which the SMEFT parameter space can be accessed through high energy top quark processes in current and future colliders.

   hep-phJHEP(2019)·114 citations
6. 06*

   Higgs inflation in metric and Palatini formalisms: Required suppression of higher dimensional operators

   Ryusuke Jinno🇩🇪 · Mio Kubota🇯🇵 · Kin-ya Oda🇯🇵 · Seong Chan Park🇰🇷

   We investigate the sensitivity of Higgs(-like) inflation to higher dimensional operators in the nonminimal couplings and in the potential, both in the metric and Palatini formalisms. We find that, while inflationary predictions are relatively stable against the higher dimensional operators around the attractor point in the metric formalism, they are extremely sensitive in the Palatini one: for the latter, inflationary predictions are spoiled by $|{\xi }_4|\gtrsim 10^{-6}$ in the nonminimal couplings $({\xi }_2{\varphi }^2+{\xi }_4{\varphi }^4+\cdots )R$, or by $|{\lambda }_6|\gtrsim 10^{-16}$ in the Jordan-frame potential ${\lambda }_4{\varphi }^4+{\lambda }_6{\varphi }^6+\cdots$ (both in Planck units). This extreme sensitivity results from the absence of attractor in the Palatini formalism. Our study underscores the challenge of realizing inflationary models with the nonminimal coupling in the Palatini formalism.

   hep-phastro-ph.COhep-thJCAP(2020)·60 citations
7. 07*

   Revisiting ${\Lambda }_b\to {\Lambda }_c$ and ${\Sigma }_b\to {\Sigma }_c$ weak decays in the light-front quark model

   Hong-Wei Ke🇨🇳 · Ning Hao · Xue-Qian Li🇨🇳

   In this work, we study ${\Lambda }_b\to {\Lambda }_c$ and ${\Sigma }_b\to {\Sigma }_c$ weak decays in the light-front quark model. As is well known, the key point for such calculations is properly evaluating the hadronic transition matrix elements which are dominated by the non-perturbative QCD effect. In our calculation, we employ the light-front quark model and rather than the traditional diquark picture, we account the two spectator light quarks as individual ones. Namely during the transition, they retain their color indices, momenta and spin polarizations unchanged. Definitely, the subsystem composed of the two light quarks is still in a color-anti-triplet and possesses a definite spin, but we do not priori assume the two light quarks to be in a bound system-diquark. Our purpose is probing the diquark picture, via comparing the results with the available data, we test the validity and applicability of the diquark structure which turns a three-body problem into a two-body one, so greatly simplifies the calculation. It is indicated that the two approaches (diquark and a subsystem within which the two light quarks are free) lead to similar numerical results even though the model parameters in the two schemes might deviate slightly. Thus, the diquark approach seems sufficiently reasonable.

   hep-phEPJC(2019)·62 citations
8. 08*

   Proton Internal Pressure in $pp$ and $\bar{p}p$ Elastic Scattering

   S. D. Campos🇧🇷

   In this work, one proposes the use of a damped confinement potential to mimic the proton internal energy. The internal pressure is calculated taking into account the occurrence of a phase transition in the $pp$ and $\bar{p}p$ total cross section. The model predicts the inversion of the positive and negative pressure regions depending on the squared energy $s_0$, where the total cross section achieves its minimum value. Considering energies below the phase transition the expected results are in accordance with the recent proton internal pressure measurement. For energies above $s_0$, the model predicts a negative pressure region near the center of the hadron surrounded by a positive pressure region.

   hep-phnucl-thInt.J.Mod.Phys.A(2019)·3 citations
9. 09*

   Reflections on the search for particle dark matter by direct experiments

   Alessandro Bottino (University of Torino, Italy and Accademia delle Scienze di Torino, Italy)🇮🇹

   Since the daring intuition by Fritz Zwicky in 1933 about the existence of dark matter in the Universe, in spite of the extensive investigations pursued over a very long lapse of time, the nature of this matter and of its (other than gravitational, if any) interactions have remained unknown. Very likely, at least a fraction of this matter consists of fossil particles; a possibility that in the last decades has prompted direct and indirect searches for these relics. Particular attention has been (and is being) devoted to the investigation about the physical effects that fossil particles, and in particular Weakly Interacting Particles (WIMPs), moving in our galaxy can produce when they scatter off the material of an appropriate underground detector. In this note we consider the present status of this type of experimental investigation, and comment about some important results obtained recently by the DAMA Collaboration and their possible developments.

   hep-phAcc. Sc. Torino, Atti Sc. Fis. 153 (2019)…·0 citations
10. 10*

    Phase Diagram, Scalar-Pseudoscalar Meson Behavior and Restoration of Symmetries in (2+1) Polyakov-Nambu-Jona-Lasinio Model

    Pedro Costa🇵🇹 · Renan Câmara Pereira🇵🇹

    We explore the phase diagram and the modification of mesonic observables in a hot and dense medium using the (2+1) Polyakov-Nambu-Jona-Lasinio model. We present the phase diagram in the ($T,{\mu }_B$)-plane, with its isentropic trajectories, paying special attention to the chiral critical end point (CEP). Chiral and deconfinement transitions are examined. The modifications of mesonic observables in the medium are explored as a tool to analyze the effective restoration of chiral symmetry for different regions of the phase diagram. It is shown that the meson masses, namely that of the kaons, change abruptly near the CEP, which can be relevant for its experimental search.

    hep-phSymmetry(2019)·16 citations
11. 11*

    Total and geometric phases, Majorana and Dirac neutrinos

    Antonio Capolupo🇮🇹

    The analysis of the total and geometric phases generated by the neutrino oscillation shows that these phases for Majorana neutrinos are depending on the representation of the mixing matrix and they are different from those of Dirac neutrinos.

    hep-ph0 citations
12. 12*

    Generic Loop Effects of New Scalars and Fermions in $b\to s{\ell }^{+}{\ell }^{-}$, $(g-2{)}_{\mu }$ and a Vector-like $4^{\mathrm{th}}$ Generation

    Pere Arnan🇪🇸 · Andreas Crivellin🇨🇭 · Marco Fedele🇪🇸 · Federico Mescia🇪🇸

    In this article we investigate in detail the possibility of accounting for the $b\to s{\ell }^{+}{\ell }^{-}$ and $(g-2{)}_{\mu }$ anomalies via loop contributions involving with new scalars and fermions. For this purpose, we first write down the most general Lagrangian which can generate the desired effects and then calculate the generic expressions for all relevant $b\to s$ Wilson coefficients. Here we extend previous analysis by allowing that the new particles can also couple to right-handed Standard Model (SM) fermions as preferred by recent $b\to s{\ell }^{+}{\ell }^{-}$ data and the anomalous magnetic moment of the muon. In the second part of this article we illustrate this generic approach for a UV complete model in which we supplement the Standard Model by a $4^{\mathrm{th}}$ generation of vector-like fermions and a real scalar field. This model allows one to coherently address the observed anomalies in $b\to s{\ell }^{+}{\ell }^{-}$ transitions and in $a_{\mu }$ without violating the bounds from other observables (in particular $B_s-{\bar{B}}_s$ mixing) or LHC searches. In fact, we find that our global fit to this model, after the recent experimental updates, is very good and prefers couplings to right-handed SM fermions, showing the importance of our generic setup and calculation performed in the first part of the article.

    hep-phJHEP(2019)·103 citations
13. 13*

    Searching for Dark Photons with Maverick Top Partners

    Jeong Han Kim🇺🇸 · Samuel D. Lane🇺🇸 · Hye-Sung Lee🇰🇷 · Ian M. Lewis🇺🇸 · Matthew Sullivan🇺🇸

    In this paper, we present a model in which an up-type vector-like quark (VLQ) is charged under a new $U(1{)}_d$ gauge force which kinetically mixes with the SM hypercharge. The gauge boson of the $U(1{)}_d$ is the dark photon, ${\gamma }_d$. Traditional searches for VLQs rely on decays into Standard Model electroweak bosons $W,Z$ or Higgs. However, since no evidence for VLQs has been found at the Large Hadron Collider (LHC), it is imperative to search for other novel signatures of VLQs beyond their traditional decays. As we will show, if the dark photon is much less massive than the Standard Model electroweak sector, $M_{{\gamma }_d}\ll M_Z$, for the large majority of the allowed parameter space the VLQ predominately decays into the dark photon and the dark Higgs that breaks the $U(1{)}_d$ . That is, this VLQ is a `maverick top partner' with nontraditional decays. One of the appeals of this scenario is that pair production of the VLQ at the LHC occurs through the strong force and the rate is determined by the gauge structure. Hence, the production of the dark photon at the LHC only depends on the strong force and is largely independent of the small kinetic mixing with hypercharge. This scenario provides a robust framework to search for a light dark sector via searches for heavy colored particles at the LHC.

    hep-phPRD(2020)·53 citations
14. 14*

    On Entanglement Entropy of Maxwell fields in 3+1 dimensions

    Candost Akkaya🇺🇸 · Alex Kovner (University of Connecticut)🇺🇸

    We consider entanglement entropy between two halves of space separated by a plane, in the theory of free photon in 3+1 dimensions. We show how to separate local gauge invariant quantities that belong to the two spatial regions. We calculate the entanglement entropy by integrating over the degrees of freedom in one half space using an approximation that assumes slow variation of the magnetic fields in longitudinal direction. We find that the entropy is proportional to the transverse area as expected. Interestingly the entanglement properties of the 2D transverse and longitudinal modes of magnetic field are quite different. While the transverse fields are entangled mostly in the neighborhood of the separation surface as expected, the longitudinal fields are entangled through an infrared mode which extends to large distances from the entanglement surface. This long range entanglement arises due to necessity to solve the no-monopole constraint condition for magnetic field.

    ↳ hep-thhep-phPLB(2020)·2 citations
15. 15*

    Probing the Early Universe with Axion Physics and Gravitational Waves

    Nicklas Ramberg🇸🇪 · Luca Visinelli🇸🇪

    We show results for the expected reach of the network of experiments that is being set up globally with the aim of detecting the "invisible" axion, in light of a non-standard thermal history of the universe. Assuming that the axion is the dark matter, we discuss the reach of a successful detection by a given experimental setup in a particular axion mass window for different modifications of the cosmological background before primordial nucleosynthesis occurred. Results are presented both in the case where the present energy budget in cold axions is produced through the vacuum realignment mechanism alone, or in the case in which axionic strings also provide with additional contributions to the axion energy density. We also show that in some cosmological models, the spectrum of gravitational waves from the axionic string network would be within reach of the future network of detectors like LISA and DECIGO-BBO. We conclude that some scenarios describing the early universe can be probed jointly by the experimental efforts on axion detection and by gravity wave multi-messenger astronomy.

    ↳ astro-ph.COhep-phPRD(2019)·84 citations
16. 16*

    Bubble-resummation and critical-point methods for $\beta$-functions at large $N$

    Tommi Alanne🇩🇪 · Simone Blasi🇩🇪 · Nicola Andrea Dondi🇩🇰

    We investigate the connection between the bubble-resummation and critical-point methods for computing the $\beta$-functions in the limit of large number of flavours, $N$, and show that these can provide complementary information. While the methods are equivalent for single-coupling theories, for multi-coupling case the standard critical exponents are only sensitive to a combination of the independent pieces entering the $\beta$-functions, so that additional input or direct computation are needed to decipher this missing information. In particular, we evaluate the $\beta$-function for the quartic coupling in the Gross-Neveu-Yukawa model, thereby completing the full system at $\mathcal{O}(1/N)$. The corresponding critical exponents would imply a shrinking radius of convergence when $\mathcal{O}(1/N^2)$ terms are included, but our present result shows that the new singularity is actually present already at $\mathcal{O}(1/N)$, when the full system of $\beta$-functions is known.

    ↳ hep-thhep-phEPJC(2019)·6 citations
17. 17*

    Optimal Electromagnetic Searches for Axion and Hidden-Photon Dark Matter

    Saptarshi Chaudhuri🇺🇸 · Kent D. Irwin🇺🇸 · Peter W. Graham🇺🇸 · Jeremy Mardon🇺🇸

    Direct-detection searches for axions and hidden photons are playing an increasingly prominent role in the search for dark matter. In this work, we derive the properties of optimal electromagnetic searches for these candidates, subject to the Standard Quantum Limit (SQL) on amplification. We show that a single-pole resonant search may possess substantial sensitivity outside of the resonator bandwidth and that optimizing this sensitivity may increase scan rates by up to five orders of magnitude at low frequencies. Additional enhancements can be obtained with resonator quality factors exceeding one million, which corresponds to the linewidth of the dark matter signal. We present the resonator optimization in the broader context of determining the optimal receiver architecture (resonant or otherwise). We discuss prior probabilities on the dark matter signal and their role in the search optimization. We determine frequency-integrated sensitivity to be the figure of merit in a wideband search and demonstrate that it is limited by the Bode-Fano criterion. The optimized single-pole resonator is approximately 75% of the Bode-Fano limit, establishing it as a fundamentally near-ideal, single-moded dark matter detection scheme. Our analysis shows, in contrast to previous work, that the scanned single-pole resonant search is superior to a reactive broadband search. Our results motivate the broad application of quantum measurement techniques evading the SQL in future axion and hidden-photon dark matter searches.

    ↳ hep-exhep-ph38 citations
18. 18*

    Three-Body Hypernuclei in Pionless Effective Field Theory

    F. Hildenbrand🇩🇪 · H.-W. Hammer🇩🇪

    We calculate the structure of three-body hypernuclei with $S=-1$ using pionless effective field theory at leading order in the isospin $I=0$ and $I=1$ sectors. In both sectors, three-body hypernuclei arise naturally from the Efimov effect and a three-body parameter is required at leading order. We apply our theory to the hypertriton and the hypothetical $\Lambda nn$ bound state and calculate the corresponding scaling factors. Moreover, we discuss constraints on the existence of the $\Lambda nn$ bound state. In particular, we elucidate universal correlations between different observables and provide explicit calculations of wave functions and matter radii.

    ↳ nucl-thhep-phPRC(2019)·59 citations
19. 19*

    Positivity in the sky

    Scott Melville🇬🇧 · Johannes Noller🇨🇭

    Positivity bounds - the consequences of requiring a unitary, causal, local UV completion - place strong restrictions on theories of dark energy and/or modified gravity. We derive and investigate such bounds for Horndeski scalar-tensor theories and for the first time pair these bounds with a cosmological parameter estimation analysis, using CMB, redshift space distortion, matter power spectrum and BAO measurements from the Planck, SDSS/BOSS and 6dF surveys. Using positivity bounds as theoretical priors, we show that their inclusion in the parameter estimation significantly improves the constraints on dark energy/modified gravity parameters. Considering as an example a specific class of models, which are particularly well-suited to illustrate the constraining power of positivity bounds, we find that these bounds eliminate over 60% of the previously allowed parameter space. We also discuss how combining positivity requirements with additional theoretical priors has the potential to further tighten these constraints: for instance also requiring a subluminal speed of gravitational waves eliminates all but 1% of the previously allowed parameter space.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2020)·99 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.