Mon·Jul 19, 2021Monday·July 19, 2021

1. 01*

   Flavour and CP symmetries in the inverse seesaw

   C. Hagedorn🇪🇸 · J. Kriewald🇫🇷 · J. Orloff🇫🇷 · A. M. Teixeira🇫🇷

   We consider an inverse seesaw mechanism of neutrino mass generation in which the Standard Model is extended by $3+3$ (heavy) sterile states, and endowed with a flavour symmetry $G_f$, $G_f=\Delta (3n^2)$ or $G_f=\Delta (6n^2)$, and a CP symmetry. These symmetries are broken in a peculiar way, so that in the charged lepton sector a residual symmetry $G_{\ell }$ is preserved, while the neutral fermion sector remains invariant under the residual symmetry $G_{\nu }=Z_2\times CP$. We study the concrete setup, where the Majorana mass term for three of the sterile states conserves $G_{\nu }$, while the remaining mass terms (i.e. couplings of left-handed leptons and heavy sterile states, as well as the Dirac-type couplings among the latter) do not break the flavour or CP symmetry. We perform a comprehensive analysis of lepton mixing for different classes of residual symmetries, giving examples for each of these, and study in detail the impact of the additional sterile states on the predictions for lepton mixing. We further confront our results with those obtained in the model-independent scenario, in which the light neutrino mass matrix leaves the residual symmetry $G_{\nu }$ intact. We consider the phenomenological impact of the inverse seesaw mechanism endowed with flavour and CP symmetries, in particular concerning effects of non-unitarity of the lepton mixing matrix (which strongly constrain the parameter space of the scenario), prospects for neutrinoless double beta decay and for charged lepton flavour violating processes.

   hep-phEPJC(2022)·20 citations
2. 02*

   High Quality QCD Axion at Gravitational Wave Observatories

   Ricardo Z. Ferreira🇪🇸 · Alessio Notari🇪🇸 · Oriol Pujolàs🇪🇸 · Fabrizio Rompineve🇺🇸

   The axion solution to the strong CP problem is delicately sensitive to Peccei-Quinn breaking contributions that are misaligned with respect to QCD instantons. Heavy QCD axion models are appealing because they avoid this so-called "quality problem". We show that generic realizations of this framework can be probed by the LIGO-Virgo-KAGRA interferometers, through the stochastic gravitational wave (GW) signal sourced by the long-lived axionic string-domain wall network, and by upcoming measurements of the neutron and proton Electric Dipole Moments. Additionally, we provide predictions for searches at future GW observatories, which will further explore the parameter space of heavy QCD axion models.

   hep-phastro-ph.COhep-thPRL(2022)·38 citations
3. 03*

   Electroweak Symmetry Non-Restoration from Dark Matter

   Oleksii Matsedonskyi🇮🇱 · James Unwin🇺🇸 · Qingyun Wang🇺🇸

   Restoration of the electroweak symmetry at temperatures around the Higgs mass is linked to tight phenomenological constraints on many baryogenesis scenarios. A potential remedy can be found in mechanisms of electroweak symmetry non-restoration (SNR), in which symmetry breaking is extended to higher temperatures due to new states with couplings to the Standard Model. Here we show that, in the presence of a second Higgs doublet, SNR can be realized with only a handful of new fermions which can be identified as viable dark matter candidates consistent with all current observational constraints. The competing requirements on this class of models allow for SNR at temperatures up to $\sim$TeV, and imply the presence of sub-TeV new physics with sizable interactions with the Standard Model. As a result this scenario is highly testable with signals in reach of next-generation collider and dark matter direct detection experiments.

   hep-phJHEP(2021)·20 citations
4. 04*

   Triple top quark production in Standard Model

   Eduard Boos🇷🇺 · Lev Dudko🇷🇺

   The triple top quark production processes have been investigated and calculated in the scope of the Standard Model. The cross sections for different channels are provided for the proton-proton collision energies of $\sqrt{s}=$ 14 and 100 TeV. The importance of the electroweak contribution has been demonstrated. For the main channels the interference between the gluon and the weak bosons mediated contributions is negative and significant, therefore the complete set of diagrams has to be taken into account. Estimated total rates are about 1.9 fb for $\sqrt{s}=14$ TeV and 530 fb for $\sqrt{s}=100$ TeV. A simple estimation of the uncertainty of the calculated cross sections gives about 20\%. The integrated luminosity of 3 ab${}^{-1}$ at HL-LHC allows expecting about 5700 events, giving a chance to detect this rare process.

   hep-phInt.J.Mod.Phys.A(2022)·18 citations
5. 05*

   Probing dark gauge boson with observations from neutron stars

   Bo-Qiang Lu🇨🇳 · Cheng-Wei Chiang🇹🇼

   We present an investigation on the production of light dark gauge bosons by the nucleon bremsstrahlung processes in the core of neutron stars. The dark vector is assumed to be a $U(1{)}_{B-L}$ gauge boson with a mass much below keV. We calculate the emission rate of the dark vector produced by the nucleon bremsstrahlung in the degenerate nuclear matter. In addition, we take into account the photon-dark vector conversion for the photon luminosity observed at infinity. Combining with the observation of J1856 surface luminosity, we find that a recently discovered excess of J1856 hard x-ray emission in the 2-8 keV energy range by XMM-Newton and Chandra x-ray telescopes could be consistently explained by a dark vector with gauge coupling $e^{\prime }=5.56\times 10^{-15}$, mixing angle $\epsilon =1.29\times 10^{-9}$, and mass $m_{{\gamma }^{\prime }}\lesssim 10^{-5}$ eV. We also show that the mixing angle $\epsilon >7.97\times 10^{-9}$ for $m_{{\gamma }^{\prime }}\lesssim 3\times 10^{-5}\mathrm{eV}$ and the gauge coupling $e^{\prime }>4.13\times 10^{-13}$ for $m_{{\gamma }^{\prime }}\lesssim 1\mathrm{keV}$ have been excluded at 95% confidence level by the J1856 surface luminosity observation. Our best-fit dark vector model satisfies the current limits on hard x-ray intensities from the Swift and INTEGRAL hard x-ray surveys. Future hard x-ray experiments such as NuSTAR may give a further test on our model.

   hep-phPRD(2022)·7 citations
6. 06*

   Decoupling of non-strange, strange and multi-strange particles from the system in Cu-Cu, Au-Au and Pb-Pb collisions at high energies

   M. Waqas · G. X. Peng · Z. Wazir

   Transverse momentum spectra of the non-strange, strange and multi-strange particles in central and peripheral Copper-Copper, Gold-Gold and Lead-Lead collisions are analyzed by the blast wave model with Boltzmann Gibbs statistics. The model results are approximately in agreement with the experimental data measured by BRAHMS, STAR, SPS, NA 49 and WA 97 Collaborations in special transverse momentum ranges. Bulk properties in terms of kinetic freeze out temperature, transverse flow velocity and freezeout volume are extracted from the transverse momentum spectra of the particles. Separate freeze out temperatures are observed for the non-strange, strange and multi-strange particles which maybe due to different reaction cross-sections of the interacting particles and it reveals the triple kinetic freezeout scenario in collisions at BRAHMS, STAR, SPS, NA 49 and WA 97 Collaborations, however the transverse flow velocity and freezeout volume are mass dependent and they decrease with the increasing the rest mass of the particles. Furthermore, the kinetic freezeout temperature, transverse flow velocity and kinetic freezeout volume in central nucleus-nucleus collisions are larger than those in peripheral collisions. Besides, the larger kinetic freezeout temperature and freezeout volume are observed in the most heaviest nuclei collisions, indicating their dependence on the size of interacting system

   hep-phChin.J.Phys.(2022)·11 citations
7. 07*

   One-loop renormalization of VBS with the electroweak chiral Lagrangian in covariant gauges

   Maria J. Herrero🇪🇸 · Roberto A. Morales🇪🇸

   This work presents a first full one-loop computation of vector boson scattering (VBS) within the non-linear effective field theory given by the bosonic sector of the usually called electroweak chiral Lagrangian (EChL). The computation is performed in the most general case of covariant $R_{\xi }$ gauges and is compared through all this work with the Standard Model case, whose computation in these covariant gauges is also novel and is presented also here. The calculation of the one-loop VBS amplitude is performed using the diagrammatic method by means of the one-particle-irreducible (1PI) Green functions that are involved in these scattering processes. The central part of this work is then devoted to the renormalization of all the n-legs one-loop 1PI Green functions involved. This renormalization is performed in the most general off-shell case with arbitrary external legs momenta. We then describe in full detail the renormalization program, which within this context of the EChL, implies to derive all the counterterms for both the electroweak parameters, like boson masses and gauge couplings, and those for the EChL coefficients. These later are crucial for the renormalization of the new divergences typically appearing when computing loops with the lowest chiral dimension Lagrangian. We present here the full list of involved divergences and counterterms in the $R_{\xi }$ gauges and derive the complete set of renormalization group equations for the EChL coefficients. In the last part of this work, we present the EChL numerical results for the one-loop cross section in the WZ channel and compare them with the SM results.

   hep-phPRD(2021)·36 citations
8. 08*

   A $\nu$ Supersymmetric Anomaly-free Atlas

   B.C. Allanach🇬🇧 · Maeve Madigan🇬🇧 · Joseph Tooby-Smith🇬🇧

   Extensions of the minimal supersymmetric standard model (MSSM) gauge group abound in the literature. Several of these include an additional $U(1{)}_X$ gauge group. Chiral fermions' charge assignments under $U(1{)}_X$ are constrained to cancel local anomalies in the extension and they determine the structure and phenomenology of it. We provide all anomaly-free charge assignments up to a maximum absolute charge of $Q_{\text{max}}=10$, assuming that the chiral superfield content of the model is that of the MSSM plus up to three Standard Model (SM) singlet superfields. The fermionic components of these SM singlets may play the rôle of right-handed neutrinos, whereas one of the scalar components may play the rôle of the flavon, spontaneously breaking $U(1{)}_X$. Easily scanned lists of the charge assignments are made publicly available on Zenodo. For the case where no restriction is placed upon $Q_{\text{max}}$, we also provide an analytic parameterisation of the general solution using simple techniques from algebraic geometry.

   hep-phhep-thJHEP(2022)·3 citations
9. 09*

   Renormalization of the radiative jet function

   Geoffrey T. Bodwin🇺🇸 · June-Haak Ee🇰🇷 · Jungil Lee🇰🇷 · Xiang-Peng Wang🇺🇸

   We show how to compute directly the renormalization/evolution of the radiative jet function that appears in the factorization theorems for $B\to \gamma \ell \nu$ and $H\to \gamma \gamma$ through a $b$-quark loop. We point out that, in order to avoid double counting of soft contributions, one should use in the factorization theorems a subtracted radiative jet function, from which soft contributions have been removed. The soft-contribution subtractions are zero-bin subtractions in the terminology of soft-collinear effective theory. We show that they can be factored from the radiative jet function and that the resulting soft-subtraction function gives rise to a nonlocal renormalization of the subtracted radiative jet function. This is a novel instance in which zero-bin subtractions lead to a nonlocality in the renormalization of a subtracted quantity that is not present in the renormalization of the unsubtracted quantity. We demonstrate the use of our formalism by computing the order-${\alpha }_s$ evolution kernel for the subtracted radiative jet function. Our result is in agreement with the result that had been inferred previously by making use of the factorization theorem for $B\to \gamma \ell \nu$, but that had been ascribed to the unsubtracted radiative jet function.

   hep-phPRD(2021)·19 citations
10. 10*

    Towards a Higgs mass determination in asymptotically safe gravity with a dark portal

    Astrid Eichhorn🇩🇰 · Martin Pauly🇩🇪 · Shouryya Ray🇩🇪

    There are indications that an asymptotically safe UV completion of the Standard Model with gravity could constrain the Higgs self-coupling, resulting in a prediction of the Higgs mass close to the vacuum stability bound in the Standard Model. The predicted value depends on the top quark mass and comes out somewhat higher than the experimental value if the current central value for the top quark mass is assumed. Beyond the Standard Model, the predicted value also depends on dark fields coupled through a Higgs portal. Here we study the Higgs self-coupling in a toy model of the Standard Model with quantum gravity that we extend by a dark scalar and fermion. Within the approximations used in arXiv:2005.03661 , there is a single free parameter in the asymptotically safe dark sector, as a function of which the predicted (toy model) Higgs mass can be lowered due to mixing effects if the dark sector undergoes spontaneous symmetry breaking.

    hep-phgr-qchep-thJHEP(2021)·37 citations
11. 11*

    Some examples of calculation of massless and massive Feynman integrals

    A. V. Kotikov🇷🇺

    We show some examples of calculations of massless and massive Feynman integrals.

    hep-phParticles(2021)·3 citations
12. 12*

    The Fourier formalism for relativistic axion-photon conversion, with astrophysical applications

    M.C. David Marsh🇸🇪 · James H. Matthews🇬🇧 · Christopher Reynolds🇬🇧 · Pierluca Carenza🇮🇹

    We study the weak mixing of photons and relativistic axion-like particles (axions) in plasmas with background magnetic fields, $\mathbf{B}$. We show that, to leading order in the axion-photon coupling, the conversion probability, $P_{\gamma \to a}$, is given by the one-dimensional power spectrum of the magnetic field components perpendicular to the particle trajectory. Equivalently, we express $P_{\gamma \to a}$ as the Fourier transform of the magnetic field autocorrelation function, and establish a dictionary between properties of the real-space magnetic field and the energy-dependent conversion probability. For axions more massive than the plasma frequency, ($m_a>{\omega }_{\mathrm{pl}}$), we use this formalism to analytically solve the problem of perturbative axion-photon mixing in a general magnetic field. In the general case where ${\omega }_{\mathrm{pl}}/m_a$ varies arbitrarily along the trajectory, we show that a naive application of the standard formalism for 'resonant' conversion can give highly inaccurate results, and that a careful calculation generically gives non-resonant contributions at least as large as the resonant contribution. Furthermore, we demonstrate how techniques based on the Fast Fourier Transform provide a new, highly efficient numerical method for calculating axion-photon mixing. We briefly discuss magnetic field modelling in galaxy clusters in the light of our results and argue, in particular, that a recently proposed 'regular' model used for studying axion-photon mixing (specifically applied to the Perseus cluster) is inconsistent with observations. Our formalism suggest new methods to search for imprints of axions, and will be important for spectrographs with percent level sensitivity, which includes existing X-ray observations by Chandra as well as the upcoming Athena mission.

    hep-phastro-ph.HEPRD(2022)·39 citations
13. 13*

    Renormalizable Models of Flavor-Specific Scalars

    Brian Batell🇺🇸 · Ayres Freitas🇺🇸 · Ahmed Ismail🇺🇸 · David McKeen🇨🇦 · Mudit Rai🇺🇸

    New light singlet scalars with flavor-specific couplings represent a phenomenologically distinctive and flavor-safe alternative to the well-studied possibility of Higgs-portal scalars. However, in contrast to the Higgs portal, flavor-specific couplings require an ultraviolet completion involving new heavy states charged under the Standard Model gauge symmetries, leading to a host of additional novel phenomena. Focusing for concreteness on a scenario with up quark-specific couplings, we investigate two simple renormalizable completions, one with an additional vector-like quark and another featuring an extra scalar doublet. We consider the implications of naturalness, flavor- and CP-violation, electroweak precision observables, and direct searches for the new states at the LHC. These bounds, while being model-dependent, are shown to probe interesting regions in the parameter space of the scalar mass and its low-energy effective coupling, complementing the essential phenomenology of the low-energy effective theory at a variety of low and medium energy experiments.

    hep-phPRD(2021)·34 citations
14. 14*

    Photon radiation effects in kinematic reconstruction of top quarks

    Didar Dobur🇧🇪 · Joscha Knolle🇧🇪 · Gianny Mestdach🇧🇪 · Kirill Skovpen🇧🇪

    Kinematic reconstruction of top quarks allows to define a set of kinematic observables relevant to various physics processes that involve top quarks and provides an additional handle for the suppression of background events. Radiation of photons in association with the top quarks alters the kinematics and the topology of the event, leading to visible systematic effects in measurable observables. The present study introduces an improved reconstruction of the top quark kinematics in the presence of photon radiation. The results are presented for processes with top quark pair production, as well as for singly-produced top quarks.

    ↳ hep-exhep-phJINST(2021)·5 citations
15. 15*

    Do quasar X-ray and UV flux measurements provide a useful test of cosmological models?

    Narayan Khadka🇺🇸 · Bharat Ratra🇺🇸

    The recent compilation of quasar (QSO) X-ray and UV flux measurements include QSOs that appear to not be standardizable via the X-ray luminosity and UV luminosity ($L_X-L_{UV}$) relation and so should not be used to constrain cosmological model parameters. Here we show that the largest of seven sub-samples in this compilation, the SDSS-4XMM QSOs that contribute about 2/3 of the total QSOs, have $L_X-L_{UV}$ relations that depend on the cosmological model assumed and also on redshift, and is the main cause of the similar problem discovered earlier for the full QSO compilation. The second and third biggest sub-samples, the SDSS-Chandra and XXL QSOs that together contribute about 30% of the total QSOs, appear standardizable, but provide only weak constraints on cosmological parameters that are not inconsistent with the standard spatially-flat $\Lambda$CDM model or with constraints from better-established cosmological probes.

    ↳ astro-ph.COgr-qchep-phhep-thMNRAS(2022)·67 citations
16. 16*

    Two-loop mass anomalous dimension in reduced quantum electrodynamics and application to dynamical fermion mass generation

    S. Metayer🇫🇷 · S. Teber🇫🇷

    We consider reduced quantum electrodynamics (RQED${}_{d_{\gamma },d_e}$) a model describing fermions in a $d_e$-dimensional space-time and interacting via the exchange of massless bosons in $d_{\gamma }$-dimensions ($d_e\le d_{\gamma }$). We compute the two-loop mass anomalous dimension, ${\gamma }_m$, in general RQED${}_{4,d_e}$ with applications to RQED${}_{4,3}$ and QED${}_4$. We then proceed on studying dynamical (parity-even) fermion mass generation in RQED${}_{4,d_e}$ by constructing a fully gauge-invariant gap equation for RQED${}_{4,d_e}$ with ${\gamma }_m$ as the only input. This equation allows for a straightforward analytic computation of the gauge-invariant critical coupling constant, ${\alpha }_c$, which is such that a dynamical mass is generated for ${\alpha }_r>{\alpha }_c$, where ${\alpha }_r$ is the renormalized coupling constant, as well as the gauge-invariant critical number of fermion flavours, $N_c$, which is such that ${\alpha }_c\to \infty$ and a dynamical mass is generated for $N<N_c$. For RQED${}_{4,3}$, our results are in perfect agreement with the more elaborate analysis based on the resolution of truncated Schwinger-Dyson equations at two-loop order. In the case of QED${}_4$, our analytical results (that use state of the art five-loop expression for ${\gamma }_m$) are in good quantitative agreement with those obtained from numerical approaches.

    ↳ hep-thcond-mat.str-elhep-phJHEP(2021)·4 citations
17. 17*

    Stochastic isocurvature constraints for axion dark matter with high-scale inflation

    Liina Jukko🇬🇧 · Arttu Rajantie🇬🇧

    Axions are among the best motivated dark matter candidates. Their production in the early Universe by the vacuum misalignment mechanism gives rise to isocurvature perturbations, which are constrained by cosmic microwave background measurements. In this paper, we compute the axion isocurvature power spectrum using spectral expansion in the stochastic Starobinsky-Yokoyama formalism, which captures non-linear effects in the axion dynamics. In contrast to most of the existing literature, we focus on high inflationary Hubble rates of order $10^{13}\mathrm{GeV}$, and demonstrate that there is a significant window in which axions can account for all or part of the dark matter abundance without violating the isocurvature bounds or tensor mode bounds. Crucially, we find that the isocurvature spectrum is dominated by non-perturbative contributions in a large part of this window. Therefore the commonly used linear approximation is not reliable in this region, making the stochastic approach essential.

    ↳ astro-ph.COhep-phhep-th10 citations
18. 18*

    Ultracold spin-balanced fermionic quantum liquids with renormalized $P$-wave interactions

    J. M. Alarcón🇪🇸 · J. A. Oller🇪🇸

    We consider a spin-balanced degenerate gas of spin-1/2 fermions whose dynamics is governed by low-energy $P$-wave interactions, characterized by the scattering volume $a_1$ and effective momentum $r_1$. The energy per particle $\bar{\mathcal{E}}$ in the many-body system is calculated by resumming the ladder diagrams comprising both particle-particle and hole-hole intermediate states, following the novel advances recently developed by us in Ann.Phys. 437,168741(2022). This allows to obtain a renormalized result for $\bar{\mathcal{E}}$ within generic cutoff regularization schemes, with $\bar{\mathcal{E}}$ directly expressed in terms of the scattering parameters $a_1$ and $r_1$, once the cut off is sent to infinity. The whole set of possible values of $a_1$ and $r_1$ is explored for the first time in the literature looking for minima in the energy per particle with $\bar{\mathcal{E}}$ given as described. They are actually found, but a further inspection reveals that the associated scattering parameters give rise to resonance poles in the complex momentum-plane with positive imaginary part, which is at odds with the Hermiticity of the Hamiltonian. We also determine that these conflictive poles, with a pole-position momentum that is smaller in absolute value than the Fermi momentum of the system, clearly impact the calculation of $\bar{\mathcal{E}}$. As a result, we conclude that unpolarized spin-1/2 fermionic normal matter interacting in $P$-wave is not stable. We also study three universal parameters around the unitary limit. Finally, the whole set of values for the parameters $a_1$, $r_1$ is characterized according to whether they give rise to unallowed poles and, if so, by attending to their pole positions relative to the Fermi momentum of the system explored.

    ↳ cond-mat.quant-gashep-phnucl-thquant-phPRC(2022)·5 citations
19. 19*

    X-ray bounds on cooling, composition, and magnetic field of the Cassiopeia A neutron star and young central compact objects

    Wynn C. G. Ho (Haverford)🇺🇸 · Yue Zhao (Alberta)🇨🇦 · Craig O. Heinke (Alberta)🇨🇦 · D. L. Kaplan (Wisconsin-Milwaukee)🇺🇸 · Peter S. Shternin (Ioffe Institute)🇷🇺 · M. J. P. Wijngaarden (Southampton)🇬🇧

    We present analysis of multiple Chandra and XMM-Newton spectra, separated by 9-19 years, of four of the youngest central compact objects (CCOs) with ages < 2500 yr: CXOU J232327.9+584842 (Cassiopeia A), CXOU J160103.1-513353 (G330.2+1.0), 1WGA J1713.4-3949 (G347.3-0.5), and XMMU J172054.5-372652 (G350.1-0.3). By fitting these spectra with thermal models, we attempt to constrain each CCO's long-term cooling rate, composition, and magnetic field. For the CCO in Cassiopeia A, 14 measurements over 19 years indicate a decreasing temperature at a ten-year rate of 2.2+/-0.2 or 2.8+/-0.3 percent (1sigma error) for a constant or changing X-ray absorption, respectively. We obtain cooling rate upper limits of 17 percent for CXOU J160103.1-513353 and 6 percent for XMMU J172054.5-372652. For the oldest CCO, 1WGA J1713.4-3949, its temperature seems to have increased by 4+/-2 percent over a ten year period. Assuming each CCO's preferred distance and an emission area that is a large fraction of the total stellar surface, a non-magnetic carbon atmosphere spectrum is a good fit to spectra of all four CCOs. If distances are larger and emission areas are somewhat smaller, then equally good spectral fits are obtained using a hydrogen atmosphere with B <= 7x10^10 G or B >= 10^12 G for CXOU J160103.1-513353, B <= 10^10 G or B >= 10^12 G for XMMU J172054.5-372652, and non-magnetic hydrogen atmosphere for 1WGA J1713.4-3949. In a unified picture of CCO evolution, our results suggest most CCOs, and hence a sizable fraction of young neutron stars, have a surface magnetic field that is low early in their life but builds up over several thousand years.

    ↳ astro-ph.HEastro-ph.SRhep-phnucl-thMNRAS(2021)·30 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.