HEP Phenomenology·hep-ph

Wed·May 15, 2019Wednesday·May 15, 2019

30 papers—22 primary·8 cross-listed·reconstructed*

01*
Can New Physics hide inside the proton?
Stefano Carrazza🇮🇹 · Celine Degrande🇧🇪 · Shayan Iranipour🇬🇧 · Juan Rojo🇳🇱 · Maria Ubiali🇬🇧
Modern global analyses of the structure of the proton include collider measurements which probe energies well above the electroweak scale. While these provide powerful constraints on the parton distribution functions (PDFs), they are also sensitive to beyond the Standard Model (BSM) dynamics if these affect the fitted distributions. Here we present a first simultaneous determination of the PDFs and BSM effects from deep-inelastic structure function data by means of the NNPDF framework. We consider representative four-fermion operators from the SM Effective Field Theory (SMEFT), quantify to which extent their effects modify the fitted PDFs, and assess how the resulting bounds on the SMEFT degrees of freedom are modified. Our results demonstrate how BSM effects that might otherwise be reabsorbed into the PDFs can be systematically disentangled.
hep-phhep-exPRL(2019)·90 citations
02*
Electric Dipole Moments From Dark Sectors
Shohei Okawa🇨🇦 · Maxim Pospelov🇨🇦 · Adam Ritz🇨🇦
We examine the sensitivity of electric dipole moments (EDMs) to new $C P$ -violating physics in a hidden (or dark) sector, neutral under the Standard Model (SM) gauge groups, and coupled via renormalizable portals. In the absence of weak sector interactions, we show that the electron EDM can be induced purely through the gauge kinetic mixing portal, but requires five loops, and four powers of the kinetic mixing parameter $ϵ$ . Allowing weak interactions, and incorporating the Higgs and neutrino portals, we show that the leading contributions to $d_{e}$ arise at two-loop order, with the main source of $C P$ -violating being in the interaction of dark Higgs and heavy singlet neutrinos. In such models, EDMs can provide new sensitivity to portal couplings that is complementary to direct probes at the intensity frontier or high energy colliders.
hep-phPRD(2019)·15 citations
03*
A Monte Carlo analysis of the SMEFT in the top quark sector
Emma Slade🇬🇧
We present a framework for carrying out global analyses of the Standard Model Effective Field Theory: SMEFiT. This approach is based on the Monte Carlo replica method, widely used in the case of NNPDF fits of the proton structure, for deriving a faithful estimate of the experimental and theoretical uncertainties. As a proof of concept of the SMEFiT methodology, we present a study of the constraints on the SMEFT provided by top quark production measurements from the LHC. We derive bounds for the 34 degrees of freedom relevant for the interpretation of the LHC top quark data and compare these bounds with previously reported constraints.
hep-phhep-exPoS(2019)·0 citations
04*
The Photon and Light $1^{--}$ Mesons
R.S. Longacre🇺🇸
In this paper we look into the world data related to the photon and the connection to light mesons with the same spin parity quantum number as the photon $J^{p} = 1^{-}$ .
hep-phnucl-th0 citations
05*
Suppression of scalar mediated FCNCs in a $S U (3)_{c} \times S U (3)_{L} \times U (1)_{X}$ -model
Katri Huitu🇫🇮 · Niko Koivunen🇫🇮
The models based on $S U (3)_{C} \times S U (3)_{L} \times U (1)_{X}$ gauge symmetry (331-models) have been advocated to explain the number of fermion families. These models place one quark family to a different representation than the other two. The traditional 331-models are plagued by scalar mediated quark flavour changing neutral currents (FCNC) at tree-level. So far there has been no concrete mechanisms to suppress these FCNCs in 331-models. Recently it has been shown that the Froggatt-Nielsen mechanism can be incorporated into the 331-setting in an economical fashion (FN331-model). The FN331-model explains both the number of fermion families in nature and their mass hierarchy simultaneously. In this work we study the Higgs mediated quark FCNCs in FN331-model. The flavour violating couplings of quarks are suppressed by the ratio of the $S U (2)_{L} \times U (1)_{Y}$ and $S U (3)_{L} \times U (1)_{X}$ breaking scales. We find that the $S U (3)_{L} \times U (1)_{X}$ -breaking scale can be as low as 5 TeV in order to pass the flavour bounds.
hep-phJHEP(2019)·16 citations
06*
Orbital angular momentum of the proton and intrinsic five-quark Fock states
C. S. An🇨🇳 · B. Saghai🇫🇷
The orbital angular momentum ( $L_{q}$ ) of the proton is studied by employing the extended constituent quark model. Contributions from different flavors, namely, up, down, strange, and charm quarks in the proton are investigated. Probabilities of the intrinsic $q q ˉ$ pairs are calculated using a $^{3} P_{0}$ transition operator to fit the sea flavor asymmetry $I_{a} = d ˉ - u ˉ = 0.118 \pm 0.012$ of the proton. Our numerical results lead to $L_{q} = 0.158 \pm 0.014$ , in agreement with $4/3 I_{a} = 0.157 \pm 0.016$ , and consistent with findings based on various other approaches.
hep-phPRD(2019)·7 citations
07*
Search for New Physics Signals via Doubly Weak B Decays
Faisal Munir Bhutta🇨🇳 · Cai Dian Lu🇨🇳
The doubly weak $b \to dd s ˉ$ and $b \to ss d ˉ$ processes are highly suppressed in the standard model that offer the unique opportunity to explore new physics signals. The wrong sign decay $B^{0} \to K^{+} π^{-}$ mediated by the $b \to dd s ˉ$ transition can be distinguished from the penguin decay $B^{0} \to K^{+} π^{-}$ , through time dependent measurement in experiments. We consider a model independent analysis of $B^{0} \to K^{+} π^{-}$ decay, within the perturbative QCD approach and explore various effective dimension-6 operators, in which large effects are possible. We also study the doubly weak exclusive process in two example models namely Randall-Sundrum model with custodial protection and the bulk-Higgs Randall-Sundrum model. A large and significant enhancement of the branching ratio, in comparison to the standard model, is observed after satisfying all the relevant constraints on the parameter spaces of these models, which requires to be searched in future experiments.
hep-phhep-ex1 citation
08*
Search for a generic heavy Higgs at the LHC
Xin Chen🇨🇳 · Yue Xu🇨🇳 · Yongcheng Wu🇨🇦 · Yu-Ping Kuang🇨🇳 · Qing Wang🇨🇳 · Hang Chen🇨🇳 · Shih-Chieh Hsu🇺🇸 · Zhen Hu🇨🇳 · Congqiao Li🇨🇳
A generic heavy Higgs has both dim-4 and effective dim-6 interactions with the Standard Model (SM) particles. The former has been the focus of LHC searches in all major Higgs production channels, just as the SM one, but with negative results so far. If the heavy Higgs is connected with Beyond Standard Model (BSM) physics at a few TeV scale, its dim-6 operators will play a very important role - they significantly enhance the Higgs momentum, and reduce the SM background in a special phase space corner to a level such that a heavy Higgs emerges, which is not possible with dim-4 operators only. We focus on the associated VH production channel, where the effect of dim-6 operators is the largest and the SM background is the lowest. Main search regions for this type of signal are identified, and substructure variables of boosted jets are employed to enhance the signal from backgrounds. The parameter space of these operators are scanned over, and expected exclusion regions with 300 fb $^{- 1}$ and 3 ab $^{- 1}$ LHC data are shown, if no BSM is present. The strategy given in this paper will shed light on a heavy Higgs which may be otherwise hiding in the present and future LHC data.
hep-phPLB(2020)·7 citations
09*
Sensitivity to neutrino-antineutrino transitions for boron neutrinos
S.J. Li🇨🇳 · J.J. Ling🇨🇳 · N. Raper🇨🇳 · M.V. Smirnov🇨🇳
Neutrino-antineutrino conversion is an important new physics process. The observation of this phenomenon could indicate total lepton number violation and potential CPT-violation. Searching for the appearance of electron antineutrinos from solar neutrinos from $^{8} B$ decay allows us to hunt for this rare process, although it can also be explained by other mechanisms or hypotheses. This analysis examines the capabilities of observing neutrino-antineutrino transition from $^{8} B$ unoscillated solar neutrinos using different liquid scintillator detector configurations. High energy reactor neutrinos and atmospheric neutrinos are the two dominant background sources. Large volume liquid scintillator detectors with deep underground shielding, placed far away from reactors and with capabilities of pulse shaped discrimination will significantly increase the search sensitivity. It is demonstrated that for the next generation of large liquid scintillator detectors being planned or under construction, the sensitivity to the average probability of neutrino-antineutrino transitions can reach $1 0^{- 6}$ , which is an order of magnitude better than the current best experimental limits.
hep-phNPB(2019)·6 citations
10*
Non-Minimal Flavour Violation in $A_{4} \times S U (5)$ SUSY GUTs
Samuel J. Rowley🇬🇧 · Jordan Bernigaud🇫🇷 · Björn Herrmann🇫🇷 · Stephen F. King🇬🇧
We study CP-conserving non-minimal flavour violation in $A_{4} \times S U (5)$ inspired Supersymmetric Grand Unified Theories (GUTs), focussing on the regions of parameter space where dark matter is successfully accommodated due to a light right-handed smuon a few GeV heavier than the lightest neutralino. We find that it is necessary to scan over all NMFV parameters simultaneously in order to properly constrain the space of the model.
hep-ph0 citations
11*
LHC Higgs CP Sensitive Observables in H to tau^+ tau^-; tau^pm to (3pi)^pm nu and Machine Learning Benefits
E. Richter-Was🇵🇱 · Z. Was🇵🇱
In phenomenological preparation for new measurements one searches for the carriers of quality signatures. Often, the first approach quantities may be difficult to measure or to provide sufficiently precise predictions for comparisons. Complexity of necessary details grow with precision. To achieve the goal one can not break the theory principles, and take into account effects which could be ignored earlier. Mixed approach where dominant effects are taken into account with intuitive even simplistic approach was developed. Non dominant corrections were controlled with the help of Monte Carlo simulations. Concept of Optimal Variables was successfully applied for many measurements. New techniques, like Machine Learning, offer solutions to exploit multidimensional signatures. Complementarity of these new and old approaches is studied for the example of Higgs Boson CP-parity measurements in H to tau^+tau^-, tau^pm \to nu (3pi)^pm cascade decays.
hep-phhep-ex1 citation
12*
Renormalisation of the Volkov propagator
Martin Lavelle🇬🇧 · David McMullan🇬🇧
The perturbative description of an electron propagating in a plane wave background is developed and loop corrections analysed. The ultraviolet divergences and associated renormalisation are studied using the sideband framework within which the multiplicative form of the corrections becomes manifest. An additional renormalisation beyond that usually expected is identified and interpreted as a loop correction to the background induced mass term. Results for the strong field sector are conjectured.
hep-phhep-thPRD(2019)·4 citations
13*
SO(3) family symmetry and axions
Mario Reig🇪🇸
Motivated by the idea of Comprehensive Unification, we consider a gauged $S O (3)$ flavor extension of the Standard Model, including right-handed neutrinos and a Peccei-Quinn symmetry. The model accommodates the observed fermion masses and mixings and yields a characteristic, successful relation among them. The Peccei-Quinn symmetry is an essential ingredient.
hep-ph0 citations
14*
The Dark Matter Phonon Coupling
Peter Cox🇯🇵 · Tom Melia🇯🇵 · Surjeet Rajendran🇺🇸
Generically, the effective coupling between the dark matter and an atom scales with the number of constituents in the atom, resulting in the effective coupling being proportional to the mass of the atom. In this limit, when the momentum transfer is also small, we show that the leading term in the scattering of a particle off the optical phonons of an array of atoms, whether in a crystal or in a molecule, vanishes. Next-generation dark matter direct detection experiments with sub-eV energy thresholds will operate in a regime where this effect is important, and the suppression can be up to order $1 0^{6}$ over naive expectations. For dark matter that couples differently to protons and neutrons, the suppression is typically of order $10 - 100$ but can be avoided through a judicious choice of material, utilising variations in nuclear ratios $Z / A$ to break the proportionality of the coupling to mass. We provide explicit illustrations of this effect by calculating structure factors for di-molecules and for the crystals NaI and sapphire.
hep-phPRD(2019)·46 citations
15*
Electro-weak Phase Transition With Three Phases in The $S U (2)_{1} \otimes S U (2)_{2} \otimes U (1)_{Y}$ Model
Vo Quoc Phong🇻🇳 · Nguyen Minh Anh🇻🇳
Our analysis shows that SM-like electroweak phase transition (EWPT) in the $S U (2)_{1} \otimes S U (2)_{2} \otimes U (1)_{Y}$ (2-2-1) model is a first-order phase transition at the $200$ GeV scale (the SM scale). Its strength ( $S$ ) is about $1 - 2.7$ and the masses of new gauge bosons are larger than $1.7$ TeV when the second VEV is larger than $535$ GeV in a three-stage EWPT scenario and the coupling constant of $S U (2)_{2}$ group must be larger than 2. Therefore, this first order EWPT can be used to fix VEVs and the coupling constant of the gauge group in electro-weak models.
hep-phInt.J.Mod.Phys.A(2019)·2 citations
16*
Compton Scattering off Pions and Electromagnetic Polarizabilities
Murray Moinester🇮🇱 · Stefan Scherer🇩🇪
The electric ( $α_{π}$ ) and magnetic ( $β_{π}$ ) Compton polarizabilities of both the charged and the neutral pion are of fundamental interest in the low-energy sector of quantum chromodynamics (QCD). Pion polarizabilities affect the shape of the $γ π \to γ π$ Compton scattering angular distribution at back scattering angles and $γ γ \to π π$ absolute cross sections. Theory derivations are given of the $γ π \to γ π$ Compton scattering differential cross section, dispersion relations, and sum rules in terms of the polarizabilities. We review experimental charged and neutral polarizability studies and theoretical predictions. The $π^{0}$ polarizabilities were deduced from DESY Crystal Ball $γ γ \to π^{0} π^{0}$ data, but with large uncertainties. The charged pion polarizabilities were deduced most recently from (1) radiative pion Primakoff scattering $π^{-} Z \to π^{-} Z γ$ at CERN COMPASS, (2) two-photon pion pair production $γ γ \to π^{+} π^{-}$ at SLAC Mark II, and (3) radiative pion photoproduction $γ p \to γ π^{+} n$ from the proton at MAMI in Mainz. A stringent test of chiral perturbation theory (ChPT) is possible based on comparisons of precision experimental charged pion polarizabilities with ChPT predictions. Only the CERN COMPASS charged pion polarizability measurement has acceptably small uncertainties. Its value $α_{π^{\pm}} - β_{π^{\pm}} = (4.0 \pm 1.8) \times 1 0^{- 4} fm^{3}$ agrees well with the two-loop ChPT prediction $α_{π^{\pm}} - β_{π^{\pm}} = (5.7 \pm 1.0) \times 1 0^{- 4} fm^{3}$ , strengthening the identification of the pion with the Goldstone boson of chiral symmetry breaking in QCD.
hep-phhep-exnucl-exnucl-thInt.J.Mod.Phys.A(2019)·24 citations
17*
Gravitino vs Neutralino LSP at the LHC
Jong Soo Kim🇿🇦 · Stefan Pokorski🇵🇱 · Krzysztof Rolbiecki🇵🇱 · Kazuki Sakurai🇵🇱
Using the latest LHC data, we analyse and compare the lower limits on the masses of gluinos and the lightest stop in two natural supersymmetric motivated scenarios: one with a neutralino being the lightest supersymmetric particle (LSP) and the other one with gravitino as the LSP and neutralino as the next-to-lightest supersymmetric particle. In the second case our analysis applies to neutralinos promptly decaying to very light gravitinos, which are of cosmological interest, and are generic for low, of order O(100) TeV, messenger scale in gauge mediation models. We find that the lower bounds on the gluino and the lightest stop masses are stronger for the gravitino LSP scenarios due to the extra handle from the decay products of neutralinos. Generally, in contrast to the neutralino LSP case the limits now extend to a region of compressed spectrum. In bino scenarios the highest excluded stop mass increases from 1000 GeV to almost 1400 GeV. Additionally, in the higgsino-like NLSP scenario the higgsinos below 650 GeV are universally excluded and the stop mass limit is $m_{t ~} > 1150$ GeV, whereas there is no limit on stops in the higgsino LSP model for $m_{h ~} = 650$ GeV. Nevertheless, we find that the low messenger scale still ameliorates the fine tuning in the electroweak potential.
hep-phJHEP(2019)·14 citations
18*
Charged charmoniumlike structures in the $e^{+} e^{-} \to ψ (3686) π^{+} π^{-}$ process based on the ISPE mechanism
Qi Huang🇨🇳 · Dian-Yong Chen🇨🇳 · Xiang Liu🇨🇳 · Takayuki Matsuki🇯🇵
In 2017, the BESIII Collaboration announced the observation of a charged charmonium-like structure in the $ψ (3686) π^{\pm}$ invariant mass spectrum of the $e^{+} e^{-} \to ψ (3686) π^{+} π^{-}$ process at different energy points, which enables us to perform a precise study of this process based on the initial single pion emission (ISPE) mechanism. In this work, we perform a combined fit to the experimental data of the cross section of $e^{+} e^{-} \to ψ (3686) π^{+} π^{-}$ , and the corresponding $ψ (3686) π^{\pm}$ and dipion invariant mass spectra. Our result shows that the observed charged charmonium-like structure in $e^{+} e^{-} \to ψ (3686) π^{+} π^{-}$ can be well reproduced based on the ISPE mechanism, and that the corresponding dipion invariant mass spectrum and cross section can be depicted with the same parameters. In fact, it provides strong evidence that the ISPE mechanism can be an underlying mechanism resulting in such novel a phenomenon.
hep-phhep-exEPJC(2019)·8 citations
19*
Heavy quarkonium suppression beyond the adiabatic limit
Jacob Boyd🇺🇸 · Thomas Cook🇺🇸 · Ajaharul Islam🇺🇸 · Michael Strickland🇺🇸
Many prior studies of in-medium quarkonium suppression have implicitly made use of an adiabatic approximation in which it was assumed that the heavy quark potential is a slowly varying function of time. In the adiabatic limit, one can separately determine the in-medium breakup rate and the medium time evolution, folding these together only at the end of the calculation. In this paper, we relax this assumption by solving the 3d Schrodinger equation in real-time in order to compute quarkonium suppression dynamically. We compare results obtained using the adiabatic approximation with real-time calculations for both harmonic oscillator and realistic complex heavy quark potentials. Using the latter, we find that, for the Upsilon(1s), the difference between the adiabatic approximation and full real-time evolution is at the few percent level, however, for the Upsilon(2s), we find that the correction can be as large as 18% in low temperature regions. For the J/Psi, we find a larger difference between the dynamical evolution and the adiabatic approximation, with the error reaching approximately 36%.
hep-phnucl-thPRD(2019)·24 citations
20*
Quantum Anomalies, Running Vacuum and Leptogenesis: an Interplay
Spyros Basilakos🇬🇷 · Nick E. Mavromatos🇬🇧 · Joan Sola🇪🇸
We discuss a connection between gravitational-wave physics, quantum theory anomalies, right-handed (sterile) neutrinos, (spontaneous) CPT Violation and Leptogenesis, within the framework of string-inspired cosmological models. In particular, we present a scenario, according to which (primordial) gravitational waves induce gravitational anomalies during inflation. This, in turn, results in the existence of an undiluted (at the exit of inflation/beginning of radiation era) bakcground of the Kalb-Ramond (KR) axion of the massless bosonic string gravitational multiplet. The latter may violate spontaneously CP and CPT symmetries, and induce leptogenesis during the radiation-dominated era in models involving right-handed neutrinos. The so-generated lepton asymmetry may then be communicated to the baryon sector by appropriate baryon-minus-lepton-number (B - L)-conserving, but (B + L)-violating, (sphaleron) processes in the Standard Model sector, thus leading to matter dominance over antimatter in the Universe.In the current (approximately de Sitter) era, the KR axion background may provide a source for an axionic dark matter in the Universe, through its mixing with other axions that are abundant in string models. As an interesting byproduct of our analysis, we demonstrate that the anomalies contribute to the vacuum energy density of the Universe terms of 'running-vacuum' type, proportional to the square of the Hubble parameter, $H^{2}$ .
hep-phgr-qchep-thPoS(2019)·8 citations
21*
Trigonometric Rosen-Morse Potential as the Quark-Antiquark Interaction Potential for Meson Properties in the Non-Relativistic Quark Model Using EAIM
M. Abu-Shady🇪🇬 · Sh. Y. Ezz-Alarab🇪🇬
Trigonometric Rosen-Morse potential is suggested as the quark-antiquark interaction potential for studying the thermodynamic properties and the masses of heavy and heavy-light mesons. For this purpose, N-radial Schrodinger equation is analytically solved using an exact analytical iteration method (EAIM). The eigenvalues of energy and corresponding wave functions are obtained in the N-dimensional space. The present results are applied for calculating the mass of heavy mesons such as charmonium, bottomonium, bc, and cs mesons and thermodynamic properties such as the mean-internal energy, the specific heat, the free energy, and the entropy. The effect of dimensional number is studied on the meson masses. A comparison is studied with other works and experimental data. The present potential provides satisfying results in comparison with other works and experimental data.
hep-phFew Body Syst.(2019)·38 citations
22*
Hadronization within the Non-Extensive Approach and the Evolution of the Parameters
Keming Shen🇭🇺 · Gergely Gábor Barnaföldi🇭🇺 · Tamás Sándor Biró🇭🇺
We review transverse momentum distributions of various identified charged particles stemming from high energy collisions fitted by various non-extensive distributions as well as by the usual Boltzmann-Gibbs statistics. We investigate the best-fit formula with the obtained $χ^{2} / n df$ values. We find that the physical mass and $s$ scaling become more explicit with heavier produced hadrons in both proton-proton and heavy-ion collisions. The spectral shape parameters, in particular the temperature $T$ and the non-extensive Tsallis parameter $q$ , do exhibit an almost linear dependence with the centrality-dependence in heavy-ion collisions.
hep-phnucl-thEPJA(2019)·18 citations
23*
Symmetry breaking and RG flows with higher dimensional operators
Nikos Irges🇬🇷 · Fotis Koutroulis🇬🇷
We discuss the role of higher dimensional operators in the spontaneous breaking of internal symmetry and scale invariance, in the context of the Lorentz invariant scalar field theory. Using the $ε$ -expansion we determine phase diagrams and demonstrate that (un)stable RG flows computed with a certain basis of dimension 6 operators in the Lagrangian, map to (un)stable RG flows of another basis related to the first by field redefinitions. Crucial is the presence of reparametrization ghosts if Ostrogradsky ghosts appear.
↳ hep-thhep-phPRD(2019)·3 citations
24*
Luminosity and Physics Considerations on HL-LHC and HE-LHC based mu-p Colliders
U. Kaya🇹🇷 · B. Ketenoglu🇹🇷 · S. Sultansoy🇹🇷 · F. Zimmermann🇨🇭
Construction of future Muon Collider tangential to the Large Hadron Collider will give opportunity to realize mu-p collisions at multi-TeV center of mass energies. Using nominal parameters of high luminosity and high energy upgrades of the LHC, as well as design parameters of muon colliders, it is shown that L_mu-p of order of 10^33 cm^-2s^-1 is achievable for different options with sqrt(s)_mu-p from 4.58 TeV to 12.7 TeV. Certainly, proposed mu-p colliders have a huge potential for clarifying QCD basics and searches for new physics.
↳ physics.acc-phhep-exhep-ph12 citations
25*
Weak scale from Planck scale -- Mass Scale Generation in Classically Conformal Two Scalar System --
Junichi Haruna🇯🇵 · Hikaru Kawai🇯🇵
In the standard model, the weak scale is the only parameter with mass dimensions. This means that the standard model itself can not explain the origin of the weak scale. On the other hand, from the results of recent accelerator experiments, except for some small corrections, the standard model has increased the possibility of being an effective theory up to the Planck scale. From these facts, it is naturally inferred that the weak scale is determined by some dynamics from the Planck scale. In order to answer this question, we rely on the multiple point criticality principle as a clue and consider the classically conformal $Z_{2} \times Z_{2}$ invariant two scalar model as a minimal model in which the weak scale is generated dynamically from the Planck scale. This model contains only two real scalar fields and does not contain any fermions and gauge fields. In this model, due to Coleman-Weinberg-like mechanism, one scalar field spontaneously breaks the $Z_{2}$ symmetry with a vacuum expectation value connected with the cutoff momentum. We investigate this using the 1-loop effective potential, renormalization group and large N limit. We also investigate whether it is possible to reproduce the mass term and vacuum expectation value of the Higgs field by coupling this model with the standard model in the Higgs portal framework. In this case, the one scalar field that does not break $Z_{2}$ can be a candidate for dark matter, and have a mass of about several TeV in appropriate parameters. On the other hand, the other scalar field breaks $Z_{2}$ and has a mass of several tens of GeV. These results can be verified in near future experiments.
↳ hep-thhep-phPTEP(2020)·11 citations
26*
Planck 2018 results. IX. Constraints on primordial non-Gaussianity
Planck Collaboration: Y. Akrami🇫🇷 · F. Arroja🇵🇹 · M. Ashdown🇬🇧 · J. Aumont🇫🇷 · C. Baccigalupi🇮🇹 · M. Ballardini🇿🇦 · A. J. Banday🇫🇷 · R. B. Barreiro🇪🇸 · N. Bartolo🇮🇹 · S. Basak🇮🇳 · K. Benabed🇫🇷 · J.-P. Bernard🇫🇷 and 147 other authors
We analyse the Planck full-mission cosmic microwave background (CMB) temperature and E-mode polarization maps to obtain constraints on primordial non-Gaussianity (NG). We compare estimates obtained from separable template-fitting, binned, and modal bispectrum estimators, finding consistent values for the local, equilateral, and orthogonal bispectrum amplitudes. Our combined temperature and polarization analysis produces the following results: f_NL^local = -0.9 +\- 5.1; f_NL^equil = -26 +\- 47; and f_NL^ortho = - 38 +\- 24 (68%CL, statistical). These results include the low-multipole (4 <= l < 40) polarization data, not included in our previous analysis, pass an extensive battery of tests, and are stable with respect to our 2015 measurements. Polarization bispectra display a significant improvement in robustness; they can now be used independently to set NG constraints. We consider a large number of additional cases, e.g. scale-dependent feature and resonance bispectra, isocurvature primordial NG, and parity-breaking models, where we also place tight constraints but do not detect any signal. The non-primordial lensing bispectrum is detected with an improved significance compared to 2015, excluding the null hypothesis at 3.5 sigma. We present model-independent reconstructions and analyses of the CMB bispectrum. Our final constraint on the local trispectrum shape is g_NLl^local = (-5.8 +\-6.5) x 10^4 (68%CL, statistical), while constraints for other trispectra are also determined. We constrain the parameter space of different early-Universe scenarios, including general single-field models of inflation, multi-field and axion field parity-breaking models. Our results provide a high-precision test for structure-formation scenarios, in complete agreement with the basic picture of the LambdaCDM cosmology regarding the statistics of the initial conditions (abridged).
↳ astro-ph.COgr-qchep-phhep-thAstron.Astrophys.(2020)·1109 citations
27*
An Inflationary Probe of Cosmic Higgs Switching
JiJi Fan🇺🇸 · Matthew Reece🇺🇸 · Yi Wang🇨🇳
A scalar Higgs field can be repeatedly switched on and off when it couples to a classically oscillating scalar modulus field. The modulus flips the Higgs mass term between stable and tachyonic values. We study a cosmological scenario in which such repeated phase transitions occur during inflation. An irrelevant operator coupling the Higgs field to the inflaton can then imprint the pattern of phase transitions in the correlation functions of the inflaton. Using both numerical and analytic studies, we show that the inflaton 2-point function carries characteristic imprints of the modulus oscillation and its effect on the Higgs boson. We briefly remark on the potential observability of such patterns and how they might be distinguished from other dynamics in the early universe.
↳ hep-thastro-ph.COhep-phJHEP(2020)·8 citations
28*
The Photon Spectrum of Asymmetric Dark Stars
Andrea Maselli🇮🇹 · Chris Kouvaris🇩🇰 · Kostas D. Kokkotas🇩🇪
Asymmetric Dark Stars, i.e., compact objects formed from the collapse of asymmetric dark matter could potentially produce a detectable photon flux if dark matter particles self-interact via dark photons that kinetically mix with ordinary photons. The morphology of the emitted spectrum is significantly different and therefore distinguishable from a typical black-body one. Given the above and the fact that asymmetric dark stars can have masses outside the range of neutron stars, the detection of such a spectrum can be considered as a smoking gun signature for the existence of these exotic stars.
↳ astro-ph.COhep-phInt.J.Mod.Phys.D(2021)·15 citations
29*
Reheating constraints to WIMPflation
Lingyuan Ji🇺🇸 · Marc Kamionkowski🇺🇸
Analyses of inflation models are usually conducted assuming a specific range---e.g., $N_{k} ≃ 50 - 60$ --of the number $N_{k}$ of $e$ -folds of inflation. However, the analysis can also be performed by taking into account constraints imposed by the physics of reheating. In this paper, we apply this analysis to a class of "WIMPflation" models in which the inflaton also plays the role of dark matter. Our analysis also updates prior WIMPflation work with more recent Planck 2018 data. With this new analysis, inflaton potentials $V (ϕ) = λ ϕ^{4}$ and $λ ϕ_{0}^{4} [1 - cos (ϕ / ϕ_{0})]^{2}$ are ruled out, while $V (ϕ) = λ ϕ_{0}^{4} {1 - exp [- (ϕ / ϕ_{0})^{2}]}^{2}$ is slightly disfavored, and $V (ϕ) = λ ϕ_{0}^{4} tanh^{4} (ϕ / ϕ_{0})$ is only viable for certain reheating conditions. In addition, we also discuss for the first time the effect of post-reheating entropy production (from, e.g., cosmological phase transitions) in this reheating-physics analysis. When accounted for, it decreases the number of $e$ -folds through $Δ N_{k} = - (1/3) ln (1 + γ)$ , where $γ \equiv δ s / s$ is the fractional increase in entropy. We discuss briefly the possible impact of entropy production to inflation-model constraints in earlier work.
↳ astro-ph.COhep-phPRD(2019)·13 citations
30*
Ricci Reheating
Toby Opferkuch🇨🇭 · Pedro Schwaller🇩🇪 · Ben A. Stefanek🇩🇪
We present a model for viable gravitational reheating involving a scalar field directly coupled to the Ricci curvature scalar. Crucial to the model is a period of kination after inflation, which causes the Ricci scalar to change sign thus inducing a tachyonic effective mass $m^{2} \propto - H^{2}$ for the scalar field. The resulting tachyonic growth of the scalar field provides the energy for reheating, allowing for temperatures high enough for thermal leptogenesis. Additionally, the required period of kination necessarily leads to a blue-tilted primordial gravitational wave spectrum with the potential to be detected by future experiments. We find that for reheating temperatures $T_{RH} ≲ 1$ GeV, the possibility exists for the Higgs field to play the role of the scalar field.
↳ gr-qcastro-ph.COhep-phJCAP(2019)·108 citations

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