Thu·Sep 17, 2020Thursday·September 17, 2020

1. 01*

   Feebly coupled vector boson dark matter in effective theory

   Basabendu Barman🇮🇳 · Subhaditya Bhattacharya🇮🇳 · Bohdan Grzadkowski🇵🇱

   A model of dark matter (DM) that communicates with the Standard Model (SM) exclusively through suppressed dimension five operator is discussed. The SM is augmented with a symmetry $U(1{)}_X\otimes Z_2$, where $U(1{)}_X$ is gauged and broken spontaneously by a very heavy decoupled scalar. The massive $U(1{)}_X$ vector boson ($X^{\mu }$) is stabilized being odd under unbroken $Z_2$ and therefore may contribute as the DM component of the universe. Dark sector field strength tensor $X^{\mu \nu }$ couples to the SM hypercharge tensor $B^{\mu \nu }$ via the presence of a heavier $Z_2$ odd real scalar $\Phi$, i.e. $1/\Lambda X^{\mu \nu }{B}_{\mu \nu }\Phi$, with $\Lambda$ being a scale of new physics. The freeze-in production of the vector boson dark matter feebly coupled to the SM is advocated in this analysis. Limitations of the so-called UV freeze-in mechanism that emerge when the maximum reheat temperature $T_{\text{RH}}$ drops down close to the scale of DM mass are discussed. The parameter space of the model consistent with the observed DM abundance is determined. The model easily and naturally avoids both direct and indirect DM searches. Possibility for detection at the Large Hadron Collider (LHC) is also considered. A Stueckelberg formulation of the model is derived.

   hep-phJHEP(2020)·34 citations
2. 02*

   The light MSSM Higgs boson mass for large $\tan \beta$ and complex input parameters

   Henning Bahl🇩🇪 · Ivan Sobolev🇩🇪 · Georg Weiglein🇩🇪

   We discuss various improvements of the prediction for the light MSSM Higgs boson mass in the hybrid framework of the public code FeynHiggs, which combines fixed-order and effective field theory results. First, we discuss the resummation of logarithmic contributions proportional to the bottom-Yukawa coupling including two-loop ${\Delta }_b$ resummation. For large $\tan \beta$, these improvements can lead to large upward shifts of the Higgs mass compared to the existing fixed-order calculations. Second, we improve the implemented EFT calculation by fully taking into account the effect of $\mathcal{C}\mathcal{P}$-violating phases. As a third improvement, we discuss the inclusion of partial N${}^3$LL resummation. The presented improvements will be implemented into FeynHiggs.

   hep-phEPJC(2020)·20 citations
3. 03*

   P,T-Odd Interactions in Atomic ${}^{129}$Xe and Phenomenological Applications

   Timo Fleig🇫🇷 · Martin Jung🇮🇹

   We calculate interaction constants for the contributions from \PT-odd scalar-pseudoscalar and tensor-pseudotensor operators to the electric dipole moment of ${}^{129}$Xe, for the first time in case of the former, using relativistic many-body theory including the effects of dynamical electron correlations. These interaction constants are necessary ingredients to relating the corresponding measurements to fundamental parameters in models of physics beyond the Standard Model. We obtain ${\alpha }_{C_S}=\left(0.71\pm 0.18\right)[10^{-23}e\text{cm}]$ and ${\alpha }_{C_T}=\left(0.520\pm 0.049\right)[10^{-20}{⟨\Sigma ⟩}_{\text{Xe}}e\text{cm}]$, respectively. We apply our results to test a phenomenological relation between the two quantities, commonly used in the literature, and discuss their present and future phenomenological impact.

   hep-phphysics.atom-phPRA(2021)·12 citations
4. 04*

   Absence of $\mu$-Problem in Grand Unification

   Gia Dvali🇩🇪 · Anna Jankowsky🇩🇪

   Using properties of Goldstino, we show that in generic grand unified theories with gravity-mediated supersymmetry breaking the $\mu$-problem is non-existent. What happens is that supersymmetry breaking universally induces the shifts of the heavy fields that generate $\mu$ and $B_{\mu }$ terms. In the leading order, these are given by the mass of gravitino and are insensitive to the scale of grand unification. The mechanism works regardless whether doublet-triplet splitting is achieved via fine-tuning or not. Moreover, we illustrate this general phenomenon on explicit examples of theories that achieve doublet-triplet splitting dynamically. These include the theories with Higgs doublet as a pseudo-Goldstone boson, as well as, the approach based on spontaneous decoupling of the light color-triplet from quarks and leptons.

   hep-phhep-thPRD(2022)·4 citations
5. 05*

   Heavy-flavor hadro-production with heavy-quark masses renormalized in the $\overline{\mathrm{MS}}$, MSR and on-shell schemes

   M.V. Garzelli🇩🇪 · L. Kemmler🇩🇪 · S. Moch🇩🇪 · O. Zenaiev🇨🇭

   We present predictions for heavy-quark production at the Large Hadron Collider making use of the $\overline{\mathrm{MS}}$ and MSR renormalization schemes for the heavy-quark mass as alternatives to the widely used on-shell renormalization scheme. We compute single and double differential distributions including QCD corrections at next-to-leading order and investigate the renormalization and factorization scale dependence as well as the perturbative convergence in these mass renormalization schemes. The implementation is based on publicly available programs, $\text{MCFM}$ and $\text{xFitter}$, extending their capabilities. Our results are applied to extract the top-quark mass using measurements of the total and differential $t\bar{t}$ production cross-sections and to investigate constraints on parton distribution functions, especially on the gluon distribution at low $x$ values, from available LHC data on heavy-flavor hadro-production.

   hep-phhep-exJHEP(2021)·31 citations
6. 06*

   Coupled-channel interpretation of the LHCb double-$J/\psi$ spectrum and hints of a new state near the $J/\psi J/\psi$ threshold

   Xiang-Kun Dong🇨🇳 · Vadim Baru🇩🇪 · Feng-Kun Guo🇨🇳 · Christoph Hanhart🇩🇪 · Alexey Nefediev🇷🇺

   Recently, the LHCb Collaboration reported pronounced structures in the invariant mass spectrum of $J/\psi$-pairs produced in proton-proton collisions at the Large Hadron Collider. In this Letter, we argue that the data can be very well described within two variants of a coupled-channel approach employing $T$-matrices consistent with unitarity: (i) with just two channels, $J/\psi J/\psi$ and $\psi (2S)J/\psi$, as long as energy-dependent interactions in these channels are allowed, or (ii) with three channels $J/\psi J/\psi$, $\psi (2S)J/\psi$ and $\psi (3770)J/\psi$ with just constant contact interactions. Both formulations hint at the existence of a near-threshold state in the $J/\psi J/\psi$ system with the quantum numbers $J^{PC}=0^{++}$ or $2^{++}$, which we refer to as $X(6200)$. We suggest experimental tests to check the existence of this state and discuss what additional channels need to be studied experimentally to allow for distinctive tests between the two mechanisms proposed. If the molecular nature of the $X(6200)$, as hinted by the three-channel approach, is confirmed, many other double-quarkonium states should exist driven by the same binding mechanism. In particular, there should be an ${\eta }_c{\eta }_c$ molecule with a similar binding energy.

   hep-phhep-exhep-latnucl-thPRL(2021)·150 citations
7. 07*

   Pentagon Functions for Scattering of Five Massless Particles

   Dmitry Chicherin🇩🇪 · Vasily Sotnikov🇩🇪

   We complete the analytic calculation of the full set of two-loop Feynman integrals required for computation of massless five-particle scattering amplitudes. We employ the method of canonical differential equations to construct a minimal basis set of transcendental functions, pentagon functions, which is sufficient to express all planar and nonplanar massless five-point two-loop Feynman integrals in the whole physical phase space. We find analytic expressions for pentagon functions which are manifestly free of unphysical branch cuts. We present a public library for numerical evaluation of pentagon functions suitable for immediate phenomenological applications.

   hep-phhep-thJHEP(2020)·164 citations
8. 08*

   Improved Neural Network Monte Carlo Simulation

   I-Kai Chen🇺🇸 · Matthew D. Klimek🇺🇸 · Maxim Perelstein🇺🇸

   The algorithm for Monte Carlo simulation of parton-level events based on an Artificial Neural Network (ANN) proposed in arXiv:1810.11509 is used to perform a simulation of $H\to 4\ell$ decay. Improvements in the training algorithm have been implemented to avoid numerical instabilities. The integrated decay width evaluated by the ANN is within 0.7% of the true value and unweighting efficiency of 26% is reached. While the ANN is not automatically bijective between input and output spaces, which can lead to issues with simulation quality, we argue that the training procedure naturally prefers bijective maps, and demonstrate that the trained ANN is bijective to a very good approximation.

   hep-phhep-exphysics.comp-phstat.MLSciPost Phys.(2021)·54 citations
9. 09*

   Unraveling the Dirac Neutrino with Cosmological and Terrestrial Detectors

   Peter Adshead🇺🇸 · Yanou Cui🇺🇸 · Andrew J. Long🇺🇸 · Michael Shamma🇺🇸

   We point out a correlation between the effective number of relativistic degrees of species $\Delta N_{\text{eff}}$, the cosmologically measured $m_{\nu ,\text{sterile}}^{\text{eff}}$, and the terrestrially measured neutrino mass sum and effective electron neutrino mass, $\Sigma m_{\nu }$ and $m_{{\nu }_e}$, which arises in the Dirac neutrino hypothesis. If the neutrinos are Dirac particles, and if the active neutrinos' sterile partners were once thermalized in the early universe, then this new cosmological relic would simultaneously contribute to the effective number of relativistic species, $\Delta N_{\text{eff}}$, and also lead to a correlation between the cosmologically-measured effective sterile neutrino mass $m_{\nu ,\text{sterile}}^{\text{eff}}$ and the terrestrially-measured active neutrino mass sum $\Sigma m_{\nu }$. We emphasize that specifically correlated deviations in $\Delta N_{\text{eff}}\gtrsim 3$, $m_{\nu ,\text{sterile}}^{\text{eff}}$ and $\Sigma m_{\nu }$ above their standard predictions could be the harbinger revealing the Dirac nature of neutrinos. We provide several benchmark examples, including Dirac leptogenesis, that predict a thermal relic population of the sterile partners, and we discuss the relevant observational prospects with current and near-future experiments. If the correlation highlighted in this work is observed in future surveys, it could be interpreted as supporting evidence of Dirac neutrino masses.

   hep-phastro-ph.COhep-exPLB(2021)·32 citations
10. 10*

    Topological mass generation in gapless systems

    Naoki Yamamoto🇯🇵 · Ryo Yokokura🇯🇵

    Mass generation of gauge fields can be universally described by topological couplings in gapped systems, such as the Abelian Higgs model in $(3+1)$ dimensions and the Maxwell-Chern-Simons theory in $(2+1)$ dimensions. These systems also exhibit the spontaneous breaking of higher-form ${\mathbb{Z}}_k$ symmetries and topological orders for level $k\ge 2$. In this paper, we consider topological mass generation in gapless systems. As a paradigmatic example, we study the axion electrodynamics with level $k$ in $(3+1)$ dimensions in background fields that hosts both gapped and gapless modes. We argue that the gapped mode is related to those in fully gapped systems in lower dimensions via dimensional reduction. We show that this system exhibits the spontaneous breaking of a higher-form ${\mathbb{Z}}_k$ symmetry despite the absence of the conventional topological order. In the case of the background magnetic field, we also derive the low-energy effective theory of the gapless mode with the quadratic dispersion relation and show that it satisfies the chiral anomaly matching.

    ↳ hep-thcond-mat.mes-hallhep-phPRD(2021)·8 citations
11. 11*

    QED interaction effects on heavy meson masses from lattice QCD+QED

    D. Hatton🇬🇧 · C. T. H. Davies🇬🇧 · G. P. Lepage🇺🇸

    Hadron masses are subject to few MeV corrections arising from QED interactions, almost entirely arising from the electric charge of the valence quarks. The QED effects include both self-energy contributions and interactions between the valence quarks/anti-quarks. By combining results from different signs of the valence quark electric charge we are able to isolate the interaction term which is dominated by the Coulomb piece, $⟨{\alpha }_{\mathrm{QED}}{e}_{q_1}{e}_{{\overline{q}}_2}/r⟩$, in the nonrelativistic limit. We study this for $D_s$, ${\eta }_c$ and $J/\psi$ mesons, working in lattice QCD plus quenched QED. We use gluon field configurations that include up, down, strange and charm quarks in the sea at multiple values of the lattice spacing. Our results, including also values for mesons with quarks heavier than charm, can be used to improve phenomenological models for the QED contributions. The QED interaction term carries information about meson structure; we derive effective sizes $⟨1/r_{\mathrm{eff}}{⟩}^{-1}$ for ${\eta }_c$, $J/\psi$ and $D_s$ of 0.206(8) fm, 0.321(14) fm and 0.307(31) fm respectively.

    ↳ hep-lathep-phPRD(2020)·8 citations
12. 12*

    Dark Matter Simulations with Primordial Black Holes in the Early Universe

    Maxim Tkachev🇷🇺 · Sergey Pilipenko🇷🇺 · Gustavo Yepes🇪🇸

    Primordial Black Holes (PBH) with masses of order $10-30M_{\odot }$ have been proposed as a possible explanation of the gravitational waves emission events recently discovered by the LIGO observatory. If true, then PBHs would constitute a sizeable fraction of the dark matter component in the Universe. Using a series of cosmological N-body simulations which include both dark matter and a variable fraction of PBHs ranging from $f_{PBH}=10^{-4}$ to $f_{PBH}=1$, we analyse the processes of formation and disruption of gravitationally bound PBH pairs, as well as the merging of both bound and unbound pairs, and estimate the probabilities of such events. We show that they are in good agreement with the constrains to the PBH abundance obtained by the LIGO and other research groups. We find that pair stability, while being a main factor responsible for the merger rate, is significantly affected by the effects of dark matter halo formation and clustering. As a side result, we also evaluate the effects of numerical errors in the stability of bound pairs, which can be useful for future research using this methodology.

    ↳ astro-ph.COgr-qchep-phMNRAS(2020)·24 citations
13. 13*

    Scalar resonance in graviton-graviton scattering at high-energies: the graviball

    D. Blas🇬🇧 · J. Martin Camalich🇪🇸 · J.A. Oller🇪🇸

    We study graviton-graviton scattering in partial-wave amplitudes after unitarizing their Born terms. In order to apply S-matrix techniques, based on unitarity and analyticity, we introduce an S-matrix associated to this resummation that is free of infrared divergences. This is achieved by removing the diverging phase factor calculated by Weinberg that multiplies the S matrix, and that stems from the virtual infrared gravitons. A scalar graviton-graviton resonance with vacuum quantum numbers (J^{PC}=0^{++}) is obtained as a pole in the nonperturbative S-wave amplitude, which we call the {\it graviball}. Its resonant effects along the physical real-s axis may peak at values substantially lower than the UV cutoff squared of the theory. For some scenarios, this phenomenon could have phenomenological consequences at relatively low-energy scales, similarly to the \sigma resonance in QCD.

    ↳ hep-thgr-qchep-phPLB(2022)·18 citations
14. 14*

    Asymptotic dynamics on the worldline for spinning particles

    Domenico Bonocore🇩🇪

    There has been a renewed interest in the description of dressed asymptotic states a la Faddeev-Kulish. In this regard, a worldline representation for asymptotic states dressed by radiation at subleading power in the soft expansion, known as the Generalized Wilson Line (GWL) in the literature, has been available for some time, and it recently found applications in the derivation of factorization theorems for scattering processes of phenomenological relevance. In this paper we revisit the derivation of the GWL in the light of the well-known supersymmetric wordline formalism for the relativistic spinning particle. In particular, we discuss the importance of wordline supersymmetry to understand the contribution of the soft background field to the asymptotic dynamics. We also provide a derivation of the GWL for the gluon case, which was not previously available in the literature, thus extending the exponentiation of next-to-soft gauge boson corrections to Yang-Mills theory. Finally, we comment about possible applications in the current research about asymptotic states in scattering amplitudes for gauge and gravity theories and their classical limit.

    ↳ hep-thhep-phJHEP(2021)·48 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.