Thu·Jun 25, 2020Thursday·June 25, 2020

1. 01*

   Simulations of Domain Walls in Two Higgs Doublet Models

   Richard A. Battye🇬🇧 · Apostolos Pilaftsis🇬🇧 · Dominic G. Viatic🇬🇧

   The Two Higgs Doublet Model predicts the emergence of 3 distinct domain wall solutions arising from the breaking of 3 accidental global symmetries, $Z_2$, CP1 and CP2, at the electroweak scale for specific choices of the model parameters. We present numerical kink solutions to the field equations in all three cases along with dynamical simulations of the models in (2+1) and (3+1) dimensions. For each kink solution we define an associated topological current. In all three cases simulations produce a network of domain walls which deviates from power law scaling in Minkowski and FRW simulations. This deviation is attributed to a winding of the electroweak group parameters around the domain walls in our simulations. We observe a local violation of the neutral vacuum condition on the domain walls in our simulations. This violation is attributed to relative electroweak transformations across the domain walls which is a general feature emerging from random initial conditions.

   hep-phastro-ph.COhep-thJHEP(2021)·30 citations
2. 02*

   Interpretation of the Galactic gamma-ray excess with the dark matter indicated by ${}^8$Be and ${}^4$He anomalous transitions

   Lian-Bao Jia🇨🇳 · Tong Li🇨🇳

   The long-standing Galactic center gamma-ray excess could be explained by GeV dark matter (DM) annihilation, while the DM interpretation seems in tension with recent joint limits from different astronomical scale observations, such as dwarf spheroidal galaxies, the Milky Way halo and galaxy groups/clusters. Motivated by ${}^8$Be and ${}^4$He anomalous transitions with possible new interactions mediated by a vector boson $X$, we consider a small fraction of DM mainly annihilating into a pair of on-shell vector boson $XX$ followed by $X\to e^{+}{e}^{-}$ in this paper. The Galactic center gamma-ray excess is explained by this DM cascade annihilation. The gamma rays are mainly from Inverse Compton Scattering emission, and the DM cascade annihilation could be compatible with joint astrophysical limits and meanwhile be allowed by the AMS-02 positron observation. The direct detection of this model is also discussed.

   hep-phCPC(2021)·2 citations
3. 03*

   LHC Constraints on Scalar Diquarks

   Bruna Pascual-Dias🇨🇦 · Pratishruti Saha🇮🇳 · David London🇨🇦

   A number of years ago, low-energy constraints on scalar diquarks, particles that couple to two quarks, were examined. It was found that the two most weakly-constrained diquarks are $D^u$ and $D^d$, colour antitriplets that couple to $u_R^i{u}_R^j$ and $d_R^i{d}_R^j$, respectively. These diquarks have not been observed at the LHC. In this paper, we add the LHC measurements to the low-energy analysis, and find that the constraints are significantly improved. As an example, denoting $x^u$ as the $D^u$ coupling to the first and second generations, for $M_{D^u}=600$ GeV, the low-energy constraint is $|x^u|\le 14.4$, while the addition of the LHC dijet measurement leads to $|x^u|\le 0.13$--$0.15$. Further improvements are obtained by adding the measurement of single top production with a $p_T$ cut. These new constraints must be taken into account in making predictions for other low-energy indirect effects of diquarks.

   hep-phJHEP(2020)·30 citations
4. 04*

   Hierarchy problem and dimension-six effective operators

   Ambalika Biswas🇮🇳 · Anirban Kundu🇮🇳 · Poulami Mondal🇮🇳

   Without any mechanism to protect its mass, the self-energy of the Higgs boson diverges quadratically, leading to the hierarchy or fine-tuning problem. One bottom-up solution is to postulate some yet-to-be-discovered symmetry which forces the sum of the quadratic divergences to be zero, or almost negligible; this is known as the Veltman condition. Even if one assumes the existence of some new physics at a high scale, the fine-tuning problem is not eradicated, although it is softer than what it would have been with a Planck scale momentum cut-off. We study such divergences in an effective theory framework, and construct the Veltman condition with dimension-six operators. We show that there are two classes of diagrams, the one-loop and the two-loop ones, that contribute to quadratic divergences, but the contribution of the latter is suppressed by a loop factor of $1/16{\pi }^2$. There are only six dimension-six operators that contribute to the one-loop category, and the Wilson coefficients of these operators play an important role towards softening the fine-tuning problem. We find the parameter space for the Wilson coefficients that satisfies the extended Veltman condition, and also discuss why one need not bother about the $d>6$ operators. The parameter space is consistent with the theoretical and experimental bounds of the Wilson coefficients, and should act as a guide to the model builders.

   hep-phPRD(2020)·8 citations
5. 05*

   Lepton number violating operators with standard model gauge fields: A survey of neutrino masses from 3-loops and their link to dark matter

   Michael Gustafsson🇩🇪 · Jose Miguel No🇪🇸 · Maximiliano A. Rivera🇨🇱

   We investigate neutrino mass generation scenarios where the lepton number breaking new physics couples only to the Standard Model (SM) right-handed charged lepton chirality. The lowest-order lepton number violating effective operator which describes this framework is a unique dimension nine operator involving SM gauge fields, ${\mathcal{O}}_9$. We find that there are two possible classes of new physics scenarios giving rise to this ${\mathcal{O}}_9$ operator. In these scenarios neutrino masses are induced radiatively via dark matter interactions, linking the dark matter to a natural explanation for the smallness of neutrino masses compared to the electroweak scale. We discuss the phenomenology and existing constraints in the different neutrino mass models within each class. In particular, we analyze the important interplay between neutrino mixing and neutrinoless double $\beta$-decay in order to predict characteristic signatures and disfavour certain scenarios.

   hep-phJHEP(2020)·6 citations
6. 06*

   Two-loop renormalization group equations for right-handed neutrino masses and phenomenological implications

   Alejandro Ibarra🇩🇪 · Patrick Strobl🇩🇪 · Takashi Toma🇨🇦

   We calculate the two-loop beta functions of the right-handed neutrino mass matrix in the Standard Model extended with right-handed neutrinos. We show that two-loop quantum effects induced by the heavier right-handed neutrinos can induce sizable contributions (sometimes dominant) to the physical masses of the lighter right-handed neutrinos. These effects can significantly affect the masses of the active neutrinos in the seesaw mechanism and the low energy phenomenology.

   hep-phPRD(2020)·14 citations
7. 07*

   Dynamical Majorana Neutrino Masses and Axions II: Inclusion of Axial Background and Anomaly Terms

   Nick E. Mavromatos🇬🇧 · Alex Soto🇨🇱

   We extend the study of a previous publication \cite{amsot} on Schwinger-Dyson dynamical mass generation for fermions and pseudoscalar fields (axion-like particles (ALP)), in field theories containing Yukawa type interactions between the fermions and ALPs, by incorporating anomaly terms and/or (constant) axial background fields. The latter are linked to some Lorentz (and CPT) violating scenarios for leptogenesis in the early Universe. We discuss both Hermitian and non-Hermitian Yukawa interactions, anomaly terms and axial backgrounds, which are all motivated in the context of some scenarios for radiative (anomalous) Majorana sterile neutrino masses in string-isnpired, low-energy, effective field theories, including attractive four-fermion interactions. We show that, for a Hermitian Yukawa interaction, there is no (pseudo)scalar dynamical mass generation, but there is fermion dynamical mass generation, provided one adds a bare (pseudo)scalar mass. For this case, the hermitian anomaly terms play a similar role in inducing dynamical mass generation for fermions as the four-fermion attractive interactions. For antihermitian Yukawa interactions, an antihermitian anomaly resists mass generation. The axial background terms assist dynamical mass generation induced by antihermitian Yukawa interactions, in the sense that the larger the magnitude of the background, the larger the dynamical mass. For hermitian Yukawa interactions, however, the situation is the opposite, in the sense that the larger the background the smaller the dynamical mass. We also compare the anomaly-induced dynamical mass with the radiative fermion mass in models of sterile neutrinos, and find that in cases where the dynamical mass occurs, the latter dominates over the anomalously generated radiative sterile-neutrino mass.

   hep-phhep-thNPB(2021)·28 citations
8. 08*

   Full-heavy tetraquarks in constituent quark models

   Xin Jin🇨🇳 · Yaoyao Xue🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳

   The full-heavy tetraquarks $bb\bar{b}\bar{b}$ and $cc\bar{c}\bar{c}$ are systematically investigated within the chiral quark model and the quark delocalization color screening model. Two structures, meson-meson and diquark-antidiquark, are considered. For the full-beauty $bb\bar{b}\bar{b}$ systems, there is no any bound state or resonance state in two structures in the chiral quark model, while the wide resonances with masses around 19.25 GeV and the quantum numbers $J^P=0^{+}$, $1^{+}$, and $2^{+}$ are possible in the quark delocalization color screening model. For the full-charm $cc\bar{c}\bar{c}$ systems, the results are qualitative consistent in two quark models. No bound state can be found in the meson-meson configuration, while in the diquark-antidiquark configuration there may exist the resonance states, with masses range between $6.3$ GeV to $7.4$ GeV, and the quantum numbers $J^P=0^{+}$, $1^{+}$, and $2^{+}$. And the separation between the diquark and the antidiquark indicates that these states may be the compact resonance states. All these full-charm resonance states are consistent with the latest results at LHCb collaboration and are worth searching in the experiments further.

   hep-phEPJC(2020)·125 citations
9. 09*

   Inclusive semileptonic ${\Lambda }_b$ decays in the Standard Model and beyond

   Pietro Colangelo🇮🇹 · Fulvia De Fazio🇮🇹 · Francesco Loparco🇮🇹

   Inclusive semileptonic decays of beauty baryons are studied using the heavy quark expansion to $\mathcal{O}(1/m_b^3)$, at leading order in ${\alpha }_s$. The case of a polarized decaying baryon is examined, with reference to ${\Lambda }_b$. An extension of the Standard Model effective Hamiltonian inducing $b\to U\ell {\bar{\nu }}_{\ell }$ transitions ($U=u,c$ and $\ell =e,\mu ,\tau$) is considered, which comprises the full set of D=6 semileptonic operators with left-handed neutrinos. The effects of the new operators in several observables are described.

   hep-phhep-exhep-latJHEP(2020)·41 citations
10. 10*

    MK single pion production model

    M. Kabirnezhad🇬🇧

    This paper presents an update to the MK model, which was developed to describe single pion production in neutrino-nucleon interactions. Originally the MK model used the helicity amplitudes and the hadronic current form-factors of the Rein and Sehgal model. The update includes a new definition for the helicity amplitudes in the first and second resonance regions, and new vector-current form factors. Fits to electron-proton scattering data were used to determine these vector-current form factors, and to assign errors to the constrained free parameters of the model.

    hep-phPRD(2020)·23 citations
11. 11*

    Universal opening of four-loop scattering amplitudes to trees

    Selomit Ramirez-Uribe🇪🇸 · Roger J. Hernandez-Pinto🇲🇽 · German Rodrigo🇪🇸 · German F. R. Sborlini🇪🇸 · William J. Torres Bobadilla🇪🇸

    The perturbative approach to quantum field theories has made it possible to obtain incredibly accurate theoretical predictions in high-energy physics. Although various techniques have been developed to boost the efficiency of these calculations, some ingredients remain specially challenging. This is the case of multiloop scattering amplitudes that constitute a hard bottleneck to solve. In this paper, we delve into the application of a disruptive technique based on the loop-tree duality theorem, which is aimed at an efficient computation of such objects by opening the loops to nondisjoint trees. We study the multiloop topologies that first appear at four loops and assemble them in a clever and general expression, the N${}^4$MLT {\it universal topology}. This general expression enables to open any scattering amplitude of up to four loops, and also describes a subset of higher order configurations to all orders. These results confirm the conjecture of a factorized opening in terms of simpler known subtopologies, which also determines how the causal structure of the entire loop amplitude is characterized by the causal structure of its subtopologies. In addition, we confirm that the loop-tree duality representation of the N${}^4$MLT universal topology is manifestly free of noncausal thresholds, thus pointing towards a remarkably more stable numerical implementation of multiloop scattering amplitudes.

    hep-phhep-thJHEP(2021)·60 citations
12. 12*

    An improved anisotropic hydrodynamics ansatz

    Huda Alalawi🇺🇸 · Michael Strickland🇺🇸

    We introduce an improved form for the anisotropic hydrodynamics distribution function which explicitly takes into account the free-streaming and equilibrating contributions separately. We demonstrate that with this improvement one can better reproduce exact results available in the literature for the evolution of moments of the distribution function, in particular, for moments which contain no powers of the longitudinal momentum in their definition (m=0 moments). Using the resulting dynamical equations, we extract the non-equilibrium attractor associated with our improved aHydro ansatz and demonstrate that the improvement also allows one to better reproduce the exact dynamical attractor obtained using kinetic theory in the relaxation time approximation, particularly at early rescaled times and for m=0 moments.

    hep-phnucl-thPRC(2020)·16 citations
13. 13*

    Very low $x$ gluon density determined by LHCb exclusive $J/\psi$ data

    Chris A. Flett🇬🇧 · Alan D. Martin🇬🇧 · Misha G. Ryskin🇬🇧 · Thomas Teubner🇬🇧

    The low $x$ behaviour of the gluon density $xg(x,{\mu }^2)$ at scale ${\mu }^2=2.4$ GeV${}^2$ is determined using exclusive $J/\psi$ production data from HERA and LHCb within the framework of collinear factorisation at next-to-leading order (NLO). It is shown that in the interval $3\times 10^{-6}<x<10^{-3}$ the gluon distribution function grows as $xg(x,{\mu }^2)\propto x^{-\lambda }$ with $\lambda =0.135\pm 0.006$. The impact this experimental data will have for the global parton distribution function (PDF) analyses in this low $x$ domain is quantified. No indication in favour of parton density saturation is observed.

    hep-phPRD(2020)·41 citations
14. 14*

    Gravitational waves from cosmic strings and first-order phase transition

    Ruiyu Zhou🇨🇳 · Ligong Bian🇨🇳

    Cosmic strings and first-order phase transition are two main sources for the stochastic gravitational wave background (SGWB). In this work, we study the stochastic gravitational wave radiation from cosmic string which is formed after the first-order phase transition. For the first-order phase transition occurs at temperature far beyond the electroweak scale, the gravitational wave signal cannot be reached by the future gravitational wave interferometers. The gravitational waves from cosmic strings that formed after the phase transition can be detected by future gravitational wave detectors in a wide range of frequency, and therefore its imprints can serve to search for firs-order phase transitions at high scales with the phase transition temperature: $\mathcal{O}(10^8)$ GeV $\le T_n$ $\le \mathcal{O}(10^{11})$ GeV.

    hep-phastro-ph.COCPC(2022)·16 citations
15. 15*

    On Constraints Between $\Delta {\alpha }_{\mathrm{had}}(M_Z^2)$ and $(g_{\mu }-2{)}_{\mathrm{HVP}}$

    Eduardo de Rafael🇫🇷

    I discuss the possibility of estimating the shift $\delta \Delta \alpha (M_Z^2)$ on the running of the EM-coupling to the $M_Z$ scale, induced by the discrepancy $\Delta a_{\mu }$ between two precise determinations of the hadronic vacuum polarization contribution to $g_{\mu }-2$. It is shown that the size of $\Delta a_{\mu }$ implies rigorous bounds on the $\delta \Delta \alpha (M_Z^2)$-shift. Any extra contribution to this minimal shift necessarily depends on the specific shape of the underlying spectral function $\frac{1}{\pi }\text{Imm}\Delta (t)$ responsible for the $\Delta a_{\mu }$-discrepancy. I show that, in the case of a quark model, the total $\Delta \alpha (M_Z^2)$-shift remains small. I also discuss the scenario where $\frac{1}{\pi }\text{Imm}\Delta (t)$ is a constant in a finite $t$-region and show that in this case, up to a $t_{\max }\precsim 5{\text{GeV}}^2$, the size of the total $\delta \Delta {\alpha }_{\mathrm{had}}^{(5)}(M_Z^2)$-shift, remains below or of the order of the present error value on $\Delta {\alpha }_{\mathrm{had}}^{(5)}(M_Z^2)$.

    hep-phhep-latPRD(2020)·48 citations
16. 16*

    Chiral Symmetry in the Confinement Phase of QCD

    S. D. Campos (Universidade Federal de São Carlos)🇧🇷

    Based on the Pomeranchuk theorem, one constructs the $\delta (s)$ parameter to measure the difference between experimental data for the particle-particle and particle-antiparticle total cross section at the same energy. The experimental data for the proton-proton and proton-antiproton total cross section were used to show that, at the same energy, this parameter tends to zero as the collision energy grows. Furthermore, one assumes a classical description of the total cross section, dividing it into a finite number of non-interacting disjoint cells, each one containing a quark-antiquark pair subject to the confinement potential. Near the minimum of the total cross section, one associates $\delta (s)$ with the entropy generated by these cells, analogous to the XY model. Using both the Quigg-Rosner and Cornell confinement potentials and neglecting other energy contributions, one can calculate the internal energy of the hadron. One obtains that both the entropy and internal energy possess the same logarithmic dependence on the spatial separation between the pairs in the cell. The Helmholtz free energy is used to estimate the transition temperature, which is far from the temperature widely related to the Quark-Gluon Plasma.

    hep-phnucl-thMod.Phys.Lett.A(2021)·1 citation
17. 17*

    Scalar Direct Detection: In-Medium Effects

    Graciela B. Gelmini🇺🇸 · Volodymyr Takhistov🇺🇸 · Edoardo Vitagliano🇺🇸

    A simple extension of the Standard Model consists of a scalar field that can potentially constitute the dark matter (DM). Significant attention has been devoted to probing light $\mathcal{O}(\lesssim 10\mathrm{eV})$ scalar DM, with a multitude of experimental proposals based on condensed matter systems as well as novel materials. However, the previously overlooked effective in-medium mixing of light scalars with longitudinal plasmons can strongly modify the original sensitivity calculations of the direct detection experiments. We implement the in-medium effects for scalar DM detection, using thermal field theory techniques, and show that the reach of a large class of direct DM detection experiments searching for light scalars is significantly reduced. This development identifies setups based on Dirac materials and tunable plasma haloscopes as particularly promising for scalar DM detection. Further, we also show that scalars with significant boost with respect to halo DM, such as those produced in the Sun, decay of other particles or by cosmic rays, will not suffer from in-medium suppression. Hence, multi-tonne direct DM detection experiments, such as those based on xenon or argon, also constitute a favorable target. We also discuss scalar mediated DM scattering.

    hep-phastro-ph.COhep-exPLB(2020)·65 citations
18. 18*

    Leptonic New Force and Cosmic-ray Boosted Dark Matter for the XENON1T Excess

    Yongsoo Jho🇰🇷 · Jong-Chul Park🇰🇷 · Seong Chan Park🇰🇷 · Po-Yan Tseng🇰🇷

    The recently reported excess in XENON1T is explained by new leptonic forces, which are free from gauge anomalies. We focus on two scenarios with and without dark matter. In Scenario #1, the gauge boson of gauged lepton number U(1)${}_{L_e-L_j}$, $j=\mu$ or $\tau$ provides non-standard interaction between solar neutrino and electron that enhances the number of electron recoil events in the XENON1T detector. In Scenario #2, the new gauge boson exclusively couples to electron and dark matter, then cosmic-ray electrons can transfer their momenta to dark matter in halo. The boosted dark matter generates the electron recoil signals of $\mathcal{O}(1)$ keV. The dark matter, aided by the new gauge interaction, efficiently heats up a neutron star in our Galaxy more than $\sim 1500$ K as a neutron star captures the halo dark matter. Therefore, we propose to utilize the future infrared telescope to test our scenario.

    hep-phPLB(2020)·97 citations
19. 19*

    Electromagnetic Signals of Inelastic Dark Matter Scattering

    Masha Baryakhtar🇺🇸 · Asher Berlin🇺🇸 · Hongwan Liu🇺🇸 · Neal Weiner🇺🇸

    Light dark sectors in thermal contact with the Standard Model naturally produce the observed relic dark matter abundance and are the targets of a broad experimental search program. A key light dark sector model is the pseudo-Dirac fermion with a dark photon mediator. The dynamics of the fermionic excited states are often neglected. We consider scenarios in which a nontrivial abundance of excited states is produced and their subsequent de-excitation yields interesting electromagnetic signals in direct detection experiments. We study three mechanisms of populating the excited state: a primordial excited fraction, a component up-scattered in the sun, and a component up-scattered in the Earth. We find that the fractional abundance of primordial excited states is generically depleted to exponentially small fractions in the early universe. Nonetheless, this abundance can produce observable signals in current dark matter searches. MeV-scale dark matter with thermal cross sections and higher can be probed by down-scattering following excitation in the sun. Up-scatters of GeV-scale dark matter in the Earth can give rise to signals in current and upcoming terrestrial experiments and X-ray observations. We comment on the possible relevance of these scenarios to the recent excess in XENON1T.

    hep-phastro-ph.COJHEP(2022)·105 citations
20. 20*

    New limits on dark photons from solar emission and keV scale dark matter

    Haipeng An🇨🇳 · Maxim Pospelov🇺🇸 · Josef Pradler🇦🇹 · Adam Ritz🇨🇦

    We provide updates to the limits on solar emission of dark photons, or more generally any light vector particle coupled to the electron vector current. The recent 2019 and 2020 electronic recoil data from XENON1T now provides more stringent constraints on these models than stellar energy loss in the sub-keV mass region. We also show that solar emission of dark photons does not provide a good fit to the recent XENON1T excess in the 2-5 keV energy bins. In contrast, the absorption of 2-4 keV mass dark photons that saturate the local dark matter mass density does provide a good fit to the excess, for mixing angles in the range $ϵ\in (4-12)\times 10^{-16}$, while satisfying astrophysical constraints. Similarly, other models utilizing the vector portal can fit the excess, including those with operators that directly couple the dark photon field strength to electron spin.

    hep-phPRD(2020)·139 citations
21. 21*

    Realizing unification in two different SO(10) models with one intermediate breaking scale

    Tommy Ohlsson🇸🇪 · Marcus Pernow🇸🇪 · Erik Sönnerlind🇸🇪

    We derive the threshold corrections in $\mathrm{SO}(10)$ grand unified models with the intermediate symmetry being flipped $\mathrm{SU}(5)\times \mathrm{U}(1)$ or $\mathrm{SU}(3)\times \mathrm{SU}(2)\times \mathrm{U}(1)\times \mathrm{U}(1)$, with the masses of the scalar fields set by the survival hypothesis. These models do not achieve gauge coupling unification if the matching conditions do not take threshold corrections into account. We present results showing the required size of threshold corrections for any value of the intermediate and unification scales. In particular, our results demonstrate that both of these models are disfavored since they require large threshold corrections to allow for unification with a predicted proton lifetime above current experimental bounds.

    hep-phEPJC(2020)·16 citations
22. 22*

    Supernova Muons: New Constraints on Z' Bosons, Axions, and ALPs

    Djuna Croon🇨🇦 · Gilly Elor🇺🇸 · Rebecca K. Leane🇺🇸 · Samuel D. McDermott🇺🇸

    New light particles produced in supernovae can lead to additional energy loss and a consequent deficit in neutrino production in conflict with the neutrinos observed from Supernova 1987A (SN1987A). Contrary to the majority of previous SN1987A studies, we examine the impact of $Z^{\prime }$ bosons, axions, and axion-like particles (ALPs) interacting with the muons produced in SN1987A. For the first time, we find constraints on generic $Z^{\prime }$ bosons coupled to muons, and apply our results to particle models including gauged $L_{\mu }-L_{\tau }$ number, $U(1{)}_{L_{\mu }-L_{\tau }}$, and gauged $B-L$ number, $U(1{)}_{B-L}$. We constrain $Z^{\prime }$ bosons with masses up to about 250-500 MeV, and down to about $10^{-9}$ in $Z^{\prime }$-muon coupling. We also extend previous work on axion-muon couplings by examining the importance of loop-level interactions, as well as performing calculations over a wider range of axion masses. We constrain muon-coupled axions from arbitrarily low masses up to about 200-500 MeV, with bounds extending down to axion-muon couplings of approximately $10^{-8}$ GeV${}^{-1}$. We conclude that supernovae broadly provide a sensitive probe of new lightly-coupled particles interacting with muons.

    hep-phastro-ph.COastro-ph.HEhep-exJHEP(2021)·174 citations
23. 23*

    Exciting the Domain Wall Soliton

    Jose J. Blanco-Pillado🇪🇸 · Daniel Jiménez-Aguilar🇪🇸 · Jon Urrestilla🇪🇸

    Many solitonic configurations in field theory have localized bound states in their spectrum of linear perturbations. This opens up the possibility of having long lived excitations of these solitons that could affect their dynamics. We start the study of these effects in the simplest configuration of a domain wall kink solution in the $\lambda {\varphi }^4$ theory in $1+1$ dimensions. We show that this solution has a single bound state and numerically study its slow decay rate in flat space. We then investigate the amplitude of this excitation by simulating a cosmological phase transition that leads to the formation of these kinks in an expanding universe. We find that kinks get formed with a $20\%$ excess of energy with respect to their lowest energy configuration. We also explore the kink solution interacting with a thermal bath and extract the amplitude of the localized excitation as a function of temperature. We note that this amplitude increases with temperature but again the extra energy in the kink never goes over the $20\%$ level. Finally, we argue that this extra energy may have important consequences in the subsequent evolution of defects in numerical simulations.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2021)·31 citations
24. 24*

    XENON1T observes tritium

    Alan E. Robinson🇨🇦

    XENON1T recently reported an excess of low-energy electron recoil events that may be attributable to either new physics or to the radioactive decay of tritium. It is likely that hydrogen is not be effectively removed by the hot zirconium getters deployed in the detector. Cosmogenic activation of the xenon underground is found to be insufficient to describe the observed excess, although gases diffusing out of detector materials from cosmogenic activation on surface may contribute. Changes in the operation of gas purification systems for XENON1T and other liquid nobel gas detectors could both confirm the tritium hypothesis and remove it from the detector.

    ↳ hep-exastro-ph.COhep-phphysics.ins-det41 citations
25. 25*

    Probing the structure of the initial state of heavy-ion collisions with $p_T$-dependent flow fluctuations

    Maurício Hippert🇧🇷 · João Guilherme Prado Barbon🇧🇷 · David Dobrigkeit Chinellato🇧🇷 · Matthew Luzum🇧🇷 · Jorge Noronha🇺🇸 · Tiago Nunes da Silva🇧🇷 · Willian Matioli Serenone🇧🇷 · Jun Takahashi🇧🇷

    The connection between initial-state geometry and anisotropic flow can be quantified through a well-established mapping between $p_T$-integrated flow harmonics and cumulants of the initial transverse energy distribution. In this paper we successfully extend this mapping to also include $p_T$-differential flow. In doing so, we find that subleading principal components of anisotropic flow can reveal previously unobserved details of the hydrodynamic response, in both the linear and the nonlinear regimes. Most importantly, we show that they provide novel information on the small-scale structures present in the initial stage of relativistic heavy-ion collisions.

    ↳ nucl-thhep-phnucl-exPRC(2020)·13 citations
26. 26*

    Simulations of a bubble wall interacting with an electroweak plasma

    Zong-Gang Mou🇳🇴 · Anders Tranberg🇳🇴 · Paul M. Saffin🇬🇧

    We perform large-scale real-time simulations of a bubble wall sweeping through an out-of-equilibrium plasma. The scenario we have in mind is the electroweak phase transition, which may be first order in extensions of the Standard Model, and produce such bubbles. The process may be responsible for baryogenesis and can generate a background of primordial cosmological gravitational waves. We study thermodynamic features of the plasma near the advancing wall, the generation of Chern-Simons number/Higgs winding number and consider the potential for CP-violation at the wall generating a baryon asymmetry. A number of technical details necessary for a proper numerical implementation are developed.

    ↳ hep-thhep-phJHEP(2021)·4 citations
27. 27*

    Electroweak baryogenesis by primordial black holes in Brans-Dicke modified gravity

    Georgios Aliferis🇬🇷 · Vasilios Zarikas🇰🇿

    A successful baryogenesis mechanism is proposed in the cosmological framework of Brans-Dicke modified gravity. Primordial black holes with small mass are produced at the end of the Brans-Dicke field domination era. The Hawking radiation reheats a spherical region around every black hole to a high temperature and the electroweak symmetry is restored there. A domain wall is formed separating the region with the symmetric vacuum from the asymmetric region where electroweak baryogenesis takes place. First order phase transition is not needed. In Brans-Dicke cosmologies black hole accretion can be strong enough to lead to black holes domination which extends the lifetime of black holes and therefore baryogenesis. The analysis of the whole scenario, finally, results in the observed baryon number which can be achieved for a CP-violation angle that is predicted by observationally accepted Two-Higgs Doublet Models. The advantage of our proposed scenario is that naturally provides both black hole domination and more efficient baryogenesis for smaller CP violating angles compared to the same mechanism applied in a FRW cosmological background.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2021)·15 citations
28. 28*

    Holographic quarkyonic matter

    Nicolas Kovensky🇬🇧 · Andreas Schmitt🇬🇧

    We point out a new configuration in the Witten-Sakai-Sugimoto model, allowing baryons in the pointlike approximation to coexist with fundamental quarks. The resulting phase is a holographic realization of quarkyonic matter, which is predicted to occur in QCD at a large number of colors, and possibly plays a role in real-world QCD as well. We find that holographic quarkyonic matter is chirally symmetric and that, for large baryon chemical potentials, it is energetically preferred over pure nuclear matter and over pure quark matter. The zero-temperature transition from nuclear matter to the quarkyonic phase is of first order in the chiral limit and for a realistic pion mass. For pion masses far beyond the physical point we observe a quark-hadron continuity due to the presence of quarkyonic matter.

    ↳ hep-thhep-phnucl-thJHEP(2020)·60 citations
29. 29*

    The $\rho$-resonance with physical pion mass from $N_f=2$ lattice QCD

    Matthias Fischer🇩🇪 · Bartosz Kostrzewa🇩🇪 · Maxim Mai🇺🇸 · Marcus Petschlies🇩🇪 · Ferenc Pittler🇨🇾 · Martin Ueding🇩🇪 · Carsten Urbach🇩🇪 · Markus Werner (for the ETM collaboration)🇩🇪

    We present the first-ever lattice computation of pi pi-scattering in the I=1 channel with Nf=2 dynamical quark flavours obtained including an ensemble with physical value of the pion mass. Employing a global fit to data at three values of the pion mass, we determine the universal parameters of the rho-resonance. We carefully investigate systematic uncertainties by determining energy eigenvalues using different methods and by comparing inverse amplitude method and Breit-Wigner type parametrizations. Overall, we find mass 786(20) MeV and width 180(6) MeV, including statistical and systematic uncertainties. In stark disagreement with the previous Nf=2 extrapolations from higher than physical pion mass results, our mass value is in good agreement with experiment, while the width is slightly too high.

    ↳ hep-lathep-phPLB(2021)·64 citations
30. 30*

    Cobordism Conjecture in AdS

    Hirosi Ooguri🇺🇸 · Tadashi Takayanagi🇯🇵

    McNamara and Vafa conjectured that any pair of consistent quantum gravity theories can be connected by a domain wall. We test the conjecture in the context of the AdS/CFT correspondence. There are topological constraints on existence of an interface between the corresponding conformal field theories. We discuss how to construct domain walls in AdS predicted by the conjecture when the corresponding conformal interfaces are prohibited by topological obstructions.

    ↳ hep-thgr-qchep-ph36 citations
31. 31*

    The XMM Cluster Survey: new evidence for the 3.5 keV feature in clusters is inconsistent with a dark matter origin

    S. Bhargava🇬🇧 · P. A. Giles🇬🇧 · A. K. Romer🇬🇧 · T. Jeltema🇺🇸 · J. Mayers🇬🇧 · A. Bermeo🇬🇧 · M. Hilton🇬🇧 · R. Wilkinson🇬🇧 · C. Vergara🇬🇧 · C. A. Collins🇬🇧 · M. Manolopoulou🇬🇧 · P. J. Rooney🇬🇧 and 5 other authors

    There have been several reports of a detection of an unexplained excess of X-ray emission at $\simeq$ 3.5 keV in astrophysical systems. One interpretation of this excess is the decay of sterile neutrino dark matter. The most influential study to date analysed 73 clusters observed by the XMM-Newton satellite. We explore evidence for a $\simeq$ 3.5 keV excess in the XMM-PN spectra of 117 redMaPPer galaxy clusters ($0.1<z<0.6$). In our analysis of individual spectra, we identify three systems with an excess of flux at $\simeq$ 3.5 keV. In one case (XCS J0003.3+0204) this excess may result from a discrete emission line. None of these systems are the most dark matter dominated in our sample. We group the remaining 114 clusters into four temperature ($T_{\mathrm{X}}$) bins to search for an increase in $\simeq$ 3.5 keV flux excess with $T_{\mathrm{X}}$ - a reliable tracer of halo mass. However, we do not find evidence of a significant excess in flux at $\simeq$ 3.5 keV in any $T_{\mathrm{X}}$ bins. To maximise sensitivity to a potentially weak dark matter decay feature at $\simeq$ 3.5 keV, we jointly fit 114 clusters. Again, no significant excess is found at $\simeq$ 3.5 keV. We estimate the upper limit of an undetected emission line at $\simeq$ 3.5 keV to be $2.41\times 10^{-6}$ photons cm${}^{-2}$ s${}^{-1}$, corresponding to a mixing angle of ${\sin }^2(2\theta )=4.4\times 10^{-11}$, lower than previous estimates from cluster studies. We conclude that a flux excess at $\simeq$ 3.5 keV is not a ubiquitous feature in clusters and therefore unlikely to originate from sterile neutrino dark matter decay.

    ↳ astro-ph.COastro-ph.HEhep-phMNRAS(2020)·32 citations
32. 32*

    Ultralight Scalar Decay and the Hubble Tension

    Mark Gonzalez🇺🇸 · Mark P. Hertzberg🇺🇸 · Fabrizio Rompineve🇺🇸

    We examine whether the Hubble tension, the mismatch between early and late measurements of $H_0$, can be alleviated by ultralight scalar fields in the early universe, and we assess its plausibility within UV physics. Since their energy density needs to rapidly redshift away, we explore decays to massless fields around the era of matter-radiation equality. We highlight a concrete implementation of ultralight pseudo-scalars, axions, that decay to an abelian dark sector. This scenario circumvents major problems of other popular realizations of early universe scalar models in that it uses a regular scalar potential that is quadratic around the minimum, instead of the extreme fine-tuning of many existing models. The idea is that the scalar is initially frozen in its potential until $H\sim m$, then efficient energy transfer from the scalar to the massless field can occur shortly after the beginning of oscillations due to resonance. We introduce an effective fluid model which captures the transition from the frozen scalar phase to the radiation dark sector phase. We perform a fit to a combined Planck 2018, BAO, SH${}_0$ES and Pantheon supernovae dataset and find that the model gives $H_0=69.9_{-0.86}^{+0.84}$ km/s/Mpc with $\Delta {\chi }^2\approx -9$ compared to $\Lambda$CDM; while inclusions of other data sets may worsen the fit. Importantly, we find that large values of the coupling between fields is required for sufficiently rapid decay: For axion-gauge field models $\varphi F\tilde{F}/\Lambda$ it requires $\Lambda \lesssim f/80$, where $2\pi f$ is the field range. We find related conclusions for scalar-scalar models $\sim \varphi {\chi }^2$ and for models that utilize perturbative decays. We conclude that these sorts of ultralight scalar models that purport to alleviate the Hubble tension, while being reasonable effective field theories, require features that are difficult to embed within UV physics.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2020)·77 citations
33. 33*

    On Hybrid Monodromy Inflation (Hic Sunt Dracones)

    Nemanja Kaloper🇺🇸 · Morgane König🇺🇸 · Albion Lawrence🇺🇸 · James H.C. Scargill🇺🇸

    We revisit two-field hybrid inflation as an effective field theory for low-scale inflation with sub-Planckian scalar field ranges. We focus on a prototype model by Stewart because it allows for a red spectral tilt, which still fits the current data. We describe the constraints on this model imposed by current CMB measurements. We then explore the stability of this model to quantum corrections. We find that for relevant, marginal, and at least a finite set of irrelevant operators, some additional mechanism is required to render the model stable to corrections from both quantum field theory and quantum gravity. We outline a possible mechanism by realizing the scalars as compact axions dual to massive $4$-form field strengths, and outline how natural hybrid inflation may be supported by strong dynamics in the dual theory.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2021)·12 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.