Thu·Sep 24, 2020Thursday·September 24, 2020

1. 01*

   Repulsive properties of hadrons in lattice QCD data and neutron stars

   Anton Motornenko🇩🇪 · Somenath Pal🇮🇳 · Abhijit Bhattacharyya🇮🇳 · Jan Steinheimer🇩🇪 · Horst Stoecker🇩🇪

   Second-order susceptibilities ${\chi }_{ij}^{11}$ of baryon, electric, and strangeness, $B$, $Q$, and $S$, charges, are calculated in the Chiral Mean Field (CMF) model and compared to available lattice QCD data. The susceptibilities are sensitive to the short range repulsive interactions between different hadron species, especially to the hardcore repulsion of hyperons. Decreasing the hyperons size, as compared to the size of the non-strange baryons, does improve significantly the agreement of the CMF model results with the Lattice QCD data. The electric charge-dependent susceptibilities are sensitive to the short range repulsive volume of mesons. The comparison with lattice QCD data suggests that strange baryons, non-strange mesons and strange mesons have significantly smaller excluded volumes than non-strange baryons. The CMF model with these modified hadron volumes allows for a mainly hadronic description of the QCD susceptibilities significantly above the chiral pseudo-critical temperature. This improved CMF model which is based on the lattice QCD data, has been used to study the properties of both cold QCD matter and neutron star matter. The phase structure in both cases is essentially unchanged, i.e. a chiral first-order phase transition occurs at low temperatures ($T_{\mathrm{CP}}\approx 17$ MeV), and hyperons survive deconfinement to higher densities than non-strange hadrons. The neutron star maximal mass remains close to 2.1$M_{\odot }$ and the mass-radius diagram is only modified slightly due to the appearance of hyperons and is in agreement with astrophysical observations.

   hep-phastro-ph.HEnucl-thPRC(2021)·23 citations
2. 02*

   Probing photophobic (rel)axion dark matter

   Nayara Fonseca🇩🇪 · Enrico Morgante🇩🇪

   We investigate the interplay between early universe cosmology and dark matter direct detection, considering axion models with naturally suppressed couplings to photons. In the context of the cosmological relaxation of the electroweak scale, we focus on a scenario of \emph{Relaxion Dark Matter}, in which the relaxion field constitutes all the observed dark matter relic density and its allowed mass range is fixed to a few $\mathrm{keV}$ by construction. In particular, we show that a relaxion particle with mass $m_{\varphi }=3.0\mathrm{keV}$ which couples to electrons with $g_{\varphi ,e}=6.8\times 10^{-14}$ is consistent with the XENON1T excess, while accounting for the observed dark matter and satisfying astro/cosmo probes. This scenario uses the electroweak scale as the link connecting the relaxion production at early times with the dark matter absorption rate in direct detection.

   hep-phastro-ph.COPRD(2021)·8 citations
3. 03*

   The lightest flavor--singlet qqq baryons as witnesses to color

   Jonathan Estévez🇪🇸 · Felipe J. Llanes-Estrada (Univ. Complutense Madrid)🇪🇸 · Víctor Martínez-Fernández (Nat. Center for Nuclear Research, Warsaw)🇵🇱 · Álvaro Pastor-Gutiérrez (Univ. Heidelberg)🇩🇪

   We present a new computation in a field-theoretical model of Coulomb gauge QCD of the first radial and angular excitations of a qqq system in a SU(3) flavor singlet state, Lambda_S. The traditional motivation for the study is that the absence of flavor singlets in the lowest-lying spectrum is a direct consequence of the color degree of freedom. (The calculation is tested with decuplet baryons Delta(1232) and Omega(1672).) We also analyze decay branching fractions of the flavor singlet baryon for various masses with the simplest effective Lagrangians.

   hep-phnucl-thPRD(2020)·4 citations
4. 04*

   A search for neutron to mirror-neutron oscillations

   C. Abel (a)🇬🇧 · N. J. Ayres (b)🇨🇭 · G. Ban (c)🇫🇷 · G. Bison (d)🇨🇭 · K. Bodek (e)🇵🇱 · V. Bondar (b)🇨🇭 · E. Chanel (f)🇨🇭 · P.-J. Chiu (b, d)🇨🇭 · C. Crawford (g)🇺🇸 · M. Daum (d)🇨🇭 · R. T. Dinani (h)🇧🇪 · S. Emmenegger (b)🇨🇭 and 31 other authors

   It has been proposed that there could be a mirror copy of the standard model particles, restoring the parity symmetry in the weak interaction on the global level. Oscillations between a neutral standard model particle, such as the neutron, and its mirror counterpart could potentially answer various standing issues in physics today. Astrophysical studies and terrestrial experiments led by ultracold neutron storage measurements have investigated neutron to mirror-neutron oscillations and imposed constraints on the theoretical parameters. Recently, further analysis of these ultracold neutron storage experiments has yielded statistically significant anomalous signals that may be interpreted as neutron to mirror-neutron oscillations, assuming nonzero mirror magnetic fields. The neutron electric dipole moment collaboration performed a dedicated search at the Paul Scherrer Institute and found no evidence of neutron to mirror-neutron oscillations. Thereby, the following new lower limits on the oscillation time were obtained: ${\tau }_{n{n}^{\prime }}>352$s at $B^{\prime }=0$ (95% C.L.), ${\tau }_{n{n}^{\prime }}>6\text{s}$ for all $0.4\mu \text{T}<B^{\prime }<25.7\mu \text{T}$ (95% C.L.), and ${\tau }_{n{n}^{\prime }}/\sqrt{\cos \beta }>9\text{s}$ for all $5.0\mu \text{T}<B^{\prime }<25.4\mu \text{T}$ (95% C.L.), where $\beta$ is the fixed angle between the applied magnetic field and the local mirror magnetic field which is assumed to be bound to the Earth. These new constraints are the best measured so far around $B^{\prime }\sim 10\mu$T, and $B^{\prime }\sim 20\mu$T.

   hep-phnucl-exquant-phPLB(2021)·55 citations
5. 05*

   Estimation of an Upper Limit on the Density of Relic Neutrinos in the Sun via the Solar ${}^8$B Neutrino Flux

   Tim Ruhe🇩🇪 · Alexander Sandrock🇩🇪

   Relic neutrinos from the early universe are predicted to have a relatively large number density, but extremely low energies. Hence, the only possible interaction proceeds via neutrino capture on beta-decaying nuclei. In case relic neutrinos are captured by beta-decaying nuclei in the Sun, the neutrinos normally emerging from the decay of these nuclei will be missing from the overall number of solar neutrinos registered in neutrino experiments. Within the Sun, ${}^8\mathrm{B}$ and three nuclei from the CNO cycle are found to be suitable for this kind of process. Their cross section as well as the possible impact on the observed number of solar neutrinos are discussed. Assuming standard neutrino oscillations, no deviations of neutrino flux measurements from the predictions of the solar standard model are observed and upper limits are derived accordingly.

   hep-phastro-ph.SR0 citations
6. 06*

   Directed flow of D mesons at RHIC and LHC: non-perturbative dynamics, longitudinal bulk matter asymmetry and electromagnetic fields

   Lucia Oliva🇩🇪 · Salvatore Plumari🇮🇹 · Vincenzo Greco🇮🇹

   We present a study of the directed flow $v_1$ for $D$ mesons discussing both the impact of initial vorticity and electromagnetic field. Recent studies predicted that $v_1$ for $D$ mesons is expected to be surprisingly much larger than that of light charged hadrons; we clarify that this is due to a different mechanism leading to the formation of a directed flow with respect to the one of the bulk matter at both relativistic and non-relativistic energies. We point out that the very large $v_1$ for $D$ mesons can be generated only if there is a longitudinal asymmetry between the bulk matter and the charm quarks and if the latter have a large non-perturbative interaction in the QGP medium. A quite good agreement with the data of STAR and ALICE is obtained if the diffusion coefficient able to correctly predict the $R_{AA}(p_T)$, $v_2(p_T)$ and $v_3(p_T)$ of $D$ meson is employed. Furthermore, the mechanism for the build-up of the $v_1(y)$ is associated to a quite small formation time that can be expected to be more sensitive to the initial high-temperature dependence of the charm diffusion coefficient. We discuss also the splitting of $v_1$ for $D^0$ and ${\bar{D}}^0$ due to the electromagnetic field that is again much larger than the one observed for charged particles and in agreement with the data by STAR that have however still error bars comparable with the splitting itself, while at LHC standard electromagnetic profile assuming a constant conductivity is not able to account for the huge splitting observed.

   hep-phnucl-thJHEP(2021)·46 citations
7. 07*

   Dark Photon Search at Yemilab, Korea

   Seon-Hee Seo🇰🇷 · Yeongduk Kim🇰🇷

   Dark photons are well motivated hypothetical dark sector particles that could account for observations that cannot be explained by the standard model of particle physics. A search for dark photons that are produced by an electron beam striking a thick tungsten target and subsequently interact in a 3 kiloton-scale neutrino detector in Yemilab, a new underground lab in Korea, is proposed. Dark photons can be produced by "darkstrahlung" or by oscillations from ordinary photons produced in the target and detected by their visible decays, "absorption" or by their oscillation to ordinary photons. By detecting the absorption process or the oscillation-produced photons, a world's best sensitivity for measurements of the dark-photon kinetic mixing parameter of ${ϵ}^2>1.5\times 10^{-13}(6.1\times 10^{-13})$ at the 95\% confidence level (C.L.) could be obtained for dark photon masses between 80 eV and 1 MeV in a year-long exposure to a 100 MeV-100 kW electron beam with zero ($10^3$) background events. In parallel, the detection of $e^{+}{e}^{-}$ pairs from decays of dark photons with mass between 1 MeV and $\sim$86 MeV would have sensitivities of ${ϵ}^2>\mathcal{O}(10^{-17})(\mathcal{O}(10^{-16}))$ at the 95% C.L. with zero ($10^3$) background events.

   hep-phhep-exJHEP(2021)·12 citations
8. 08*

   WIMPs at High Energy Muon Colliders

   Tao Han🇺🇸 · Zhen Liu🇺🇸 · Lian-Tao Wang🇺🇸 · Xing Wang🇺🇸

   The Weakly Interacting Massive Particle (WIMP) paradigm is one of the most compelling scenarios for particle dark matter (DM). We show in this paper that a high energy muon collider can make decisive statements about the WIMP DM, and this should serve as one of its main physics driver cases. We demonstrate this by employing the DM as the lightest member of an electroweak (EW) multiplet, which is a simple, yet one of the most challenging WIMP scenarios given its minimal collider signature and high thermal target mass scale of 1 TeV$-$23 TeV. We perform a first study of the reach of high energy muon colliders, focusing on the simple, inclusive and conservative signals with large missing mass, through the mono-photon, VBF di-muon and a novel mono-muon channel. Using these inclusive signals, it is possible to cover the thermal targets of doublet and triplet with a 10 TeV muon collider. Higher energies, 14 TeV$-$75 TeV, would ensure a $5\sigma$ reach above the thermal targets for the higher EW multiplets. We also estimate the reach of a search for disappearing tracks, demonstrating the potential significant enhancement of the sensitivity.

   hep-phhep-exPRD(2021)·146 citations
9. 09*

   Higgs Coupling Measurements and the Scale of New Physics

   Fayez Abu-Ajamieh🇫🇷 · Spencer Chang🇺🇸 · Miranda Chen🇺🇸 · Markus A. Luty🇺🇸

   A primary goal of present and future colliders is measuring the Higgs couplings to Standard Model (SM) particles. Any observed deviation from the SM predictions for these couplings is a sign of new physics whose energy scale can be bounded from above by requiring tree-level unitarity. In this paper, we extend previous work on unitarity bounds from the Higgs cubic coupling to Higgs couplings to vector bosons and top quarks. We find that HL-LHC measurements of these couplings compatible with current experimental bounds may point to a scale that can be explored at the HL-LHC or a next-generation collider. Our approach is completely model-independent: we assume only that there are no light degrees of freedom below the scale of new physics, and allow arbitrary values for the infinitely many couplings beyond the SM as long as they are in agreement with current measurements. We also extend and clarify the methodology of this analysis, and show that if the scale of new physics is above the TeV scale, then the deviations can be described by the leading higher-dimension gauge invariant operator, as in the SM effective field theory.

   hep-phhep-exhep-thJHEP(2021)·40 citations
10. 10*

    Vector Leptoquarks Beyond Tree Level III: Vector-like Fermions and Flavor-Changing Transitions

    Javier Fuentes-Martin🇨🇭 · Gino Isidori🇨🇭 · Matthias König🇨🇭 · Nudzeim Selimovic🇨🇭

    Extending previous work on this subject, we evaluate the impact of vector-like fermions at next-to-leading order accuracy in models with a massive vector leptoquark embedded in the $SU(4)\times SU(3{)}^{\prime }\times SU(2{)}_L\times U(1{)}_X$ gauge group. Vector-like fermions induce new sources of flavor symmetry breaking, resulting in tree-level flavor-changing couplings for the leptoquark not present in the minimal version of the model. These, in turn, lead to a series of non-vanishing flavor-changing neutral-current amplitudes at the loop level. We systematically analyze these effects in semileptonic, dipole and $\Delta F=2$ operators. The impact of these corrections in $b\to s\nu \nu$ and $b\to c\tau \nu$ observables are discussed in detail. In particular, we show that, in the parameter region providing a good fit to the $B$-physics anomalies, the model predicts a $10\%$ to $50\%$ enhancement of $\mathcal{B}(B\to K^{(\ast )}\nu \nu )$.

    hep-phPRD(2020)·77 citations
11. 11*

    Small-scale Cosmic Signatures of Feebly Interacting Massive Particles

    Patrick Hager🇩🇪 · Alexis Kassiteridis🇩🇪

    Feebly Interacting Massive Particles (FIMPs), if they exist, should be notoriously difficult to detect even indirectly. In order to constrain them, we derive bounds for feeble theories sourced via Standard Model fields by investigating their predicted signatures regarding small-scale structure formation. To achieve this, we obtain an analytic approximation for the phase-space distribution function for a generic dimension $\ell$ scattering operator. As a proof of concept, realizations of such theories are discussed, which provide a viable thermal evolution and are able to solidly solve the enduring small-scale structure challenges appearing in $\Lambda$CDM cosmology.

    hep-ph3 citations
12. 12*

    Scale and isolation sensitivity of diphoton distributions at the LHC

    Thomas Gehrmann🇨🇭 · Nigel Glover🇬🇧 · Alexander Huss🇨🇭 · James Whitehead🇬🇧

    Precision measurements of diphoton distributions at the LHC display some tension with theory predictions, obtained at next-to-next-to-leading order (NNLO) in QCD. We revisit the theoretical uncertainties arising from the approximation of the experimental photon isolation by smooth-cone isolation, and from the choice of functional form for the renormalisation and factorisation scales. We find that the resulting variations are substantial overall, and enhanced in certain regions. We discuss the infrared sensitivity at the cone boundaries in cone-based isolation in related distributions. Finally, we compare predictions made with alternative choices of dynamical scale and isolation prescriptions to experimental data from ATLAS at 8 TeV, observing improved agreement. This contrasts with previous results, highlighting that scale choice and isolation prescription are potential sources of theoretical uncertainty that were previously underestimated.

    hep-phJHEP(2021)·42 citations
13. 13*

    Centrality dependence of limiting fragmentation

    B. Kellers🇩🇪 · G. Wolschin🇩🇪

    We investigate the centrality-dependent validity of the limiting-fragmentation hypothesis in relativistic heavy-ion collisions at energies reached at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). A phenomenological analysis of Au-Au and Pb-Pb collisions within a three-source relativistic diffusion model (RDM) is performed at sqrt(s_NN) = 19.6, 62.4, 130, 200, 2760 and 5023 GeV using four centrality cuts at each energy. Linear and nonlinear expressions for the rapidity drift function are tested and their physical relevance is discussed. Our results are compatible with the limiting-fragmentation conjecture for the investigated centralities in the full energy range. The number of particles in the fragmentation and fireball sources are found to depend on sqrt(s_NN) logarithmically and cubic-logarithmically, respectively.

    hep-phEPJA(2021)·3 citations
14. 14*

    Squeezing the Parameter Space for Lorentz Violation in the Neutrino Sector by Additional Decay Channels

    Ulrich D. Jentschura🇺🇸

    The hypothesis of Lorentz violation in the neutrino sector has intrigued scientists for the last two to three decades. A number of theoretical arguments support the emergence of such violations first and foremost for neutrinos, which constitute the "most elusive" and "least interacting" particles known to mankind. It is of obvious interest to place stringent bounds on the Lorentz-violating parameters in the neutrino sector. In the past, the most stringent bounds have been placed by calculating the probability of neutrino decay into a lepton pair, a process made kinematically feasible by Lorentz violation in the neutrino sector, above a certain threshold. However, even more stringent bounds can be placed on the Lorentz-violating parameters if one takes into account, additionally, the possibility of neutrino splitting, i.e., of neutrino decay into a neutrino of lower energy, accompanied by "neutrino-pair Cerenkov radiation". This process has negligible threshold and can be used to improve the bounds on Lorentz-violating parameters in the neutrino sector. Finally, we take the opportunity to discuss the relation of Lorentz and gauge symmetry breaking, with a special emphasis on the theoretical models employed in our calculations.

    hep-phParticles(2020)·8 citations
15. 15*

    Effects of Non-locality in Gravity and Quantum Theory

    Jens Boos🇨🇦

    Spacetime---the union of space and time---is both the actor and the stage during physical processes in our fascinating Universe. In Lorentz invariant local theories, the existence of a maximum signalling speed (the "speed of light") determines a notion of causality in spacetime, distinguishing the past from the future, and the cause from the effect. This thesis is dedicated to the study of \emph{deviations} from locality. Focussing on a particular class of \emph{non-local} theories that is both Lorentz invariant and free of ghosts, we aim to understand the effects of such non-local physics in both gravity and quantum theory. Non-local ghost-free theories are accompanied by a parameter $\ell$ of dimension length that parametrizes the scale of non-locality, and for that reason we strive to express all effects of non-locality in terms of this symbol. In the limiting case of $\ell =0$ one recovers the local theory, and the effects of non-locality vanish. In order to address these questions we develop the notion of non-local Green functions [...]. The results presented in this thesis establish several effects of a Lorentz invariant, ghost-free non-locality in the areas of both gravitational and quantum physics. (Full abstract in document.)

    ↳ gr-qchep-phhep-thquant-ph24 citations
16. 16*

    On Quantum Simulation Of Cosmic Inflation

    Junyu Liu🇺🇸 · Yue-Zhou Li🇨🇦

    In this paper, we generalize Jordan-Lee-Preskill, an algorithm for simulating flat-space quantum field theories, to 3+1 dimensional inflationary spacetime. The generalized algorithm contains the encoding treatment, the initial state preparation, the inflation process, and the quantum measurement of cosmological observables at late time. The algorithm is helpful for obtaining predictions of cosmic non-Gaussianities, serving as useful benchmark problems for quantum devices, and checking assumptions made about interacting vacuum in the inflationary perturbation theory. Components of our work also include a detailed discussion about the lattice regularization of the cosmic perturbation theory, a detailed discussion about the in-in formalism, a discussion about encoding using the HKLL-type formula that might apply for both dS and AdS spacetimes, a discussion about bounding curvature perturbations, a description of the three-party Trotter simulation algorithm for time-dependent Hamiltonians, a ground state projection algorithm for simulating gapless theories, a discussion about the quantum-extended Church-Turing Thesis, and a discussion about simulating cosmic reheating in quantum devices.

    ↳ quant-phgr-qchep-phhep-thPRD(2021)·14 citations
17. 17*

    Local Equilibrium Spin Distribution From Detailed Balance

    Ziyue Wang🇨🇳 · Xingyu Guo🇨🇳 · Pengfei Zhuang🇨🇳

    As the core ingredient for spin polarization, the local equilibrium spin distribution function is derived from the detailed balance principle. The kinetic theory for interacting fermionic systems is applied to the Nambu--Jona-Lasinio model at quark level. Under the semi-classical expansion with respect to $\hslash$ and non-perturbative expansion with respect to $N_c$, the kinetic equations for the vector and axial-vector distribution functions are derived with collision terms. It is found that, for an initially unpolarized system, non-zero spin polarization can be generated at the order of $\hslash$ from the coupling between the vector and axial-vector charges. The local equilibrium spin polarization is derived from the requirement of detailed balance. It arises from the thermal vorticity and is orthogonal to the particle momentum.

    ↳ hep-thhep-phEPJC(2021)·64 citations
18. 18*

    On diagonal representatives in boundary condition matrices on orbifolds

    Yoshiharu Kawamura🇯🇵 · Yasunari Nishikawa🇯🇵

    We study diagonal representatives of boundary condition matrices on the orbifolds $S^1/Z_2$ and $T^2/Z_m$ ($m=2,3,4,6$). We give an alternative proof of the existence of diagonal representatives in each equivalent class of boundary condition matrices on $S^1/Z_2$, using a matrix exponential representation, and show that they do not necessarily exist on $T^2/Z_2$, $T^2/Z_3$, and $T^2/Z_4$. Each equivalence class on $T^2/Z_6$ has a diagonal representative, because its boundary conditions are determined by a single unitary matrix.

    ↳ hep-thhep-phInt.J.Mod.Phys.A(2020)·5 citations
19. 19*

    Static magnetic dipole solutions of Einstein-Maxwell equations from the soliton solutions of a Kerr object

    Avinanda Chaudhuri🇮🇳 · S Nandi🇮🇳 · S Chaudhuri🇮🇳

    Static magnetic dipole solutions of Einstein-Maxwell equations from the soliton solutions of a Kerr object

    ↳ gr-qchep-phCan.J.Phys.(2022)·1 citation
20. 20*

    Lux ex tenebris: The imprint of annihilating dark matter on the intergalactic medium during Cosmic Dawn

    Florian List🇦🇺 · Pascal J. Elahi🇦🇺 · Geraint F. Lewis🇦🇺

    Upcoming measurements of the highly redshifted 21cm line with next-generation radio telescopes such as HERA and SKA will provide the intriguing opportunity to probe dark matter (DM) physics during the Epoch of Reionization (EoR), Cosmic Dawn, and the Dark Ages. With HERA already under construction, there is a pressing need to thoroughly understand the impact of DM physics on the intergalactic medium (IGM) during these epochs. We present first results of a hydrodynamic simulation suite with $2\times 512^3$ particles in a $(100h^{-1}\text{Mpc}{)}^3$ box with DM annihilation and baryonic cooling physics. We focus on redshift $z\sim 11$, just before reionization starts in our simulations, and discuss the imprint of DM annihilation on the IGM and on structure formation. We find that whereas structure formation is not affected by thermal WIMPs heavier than $m_{\chi }\gtrsim 100\text{MeV}$, heating from $\mathcal{O}$(GeV) DM particles may leave a significant imprint on the IGM that alters the 21cm signal. Cold gas in low density regions is particularly susceptible to the effects of DM heating. We note, however, that delayed energy deposition is not currently accounted for in our simulations.

    ↳ astro-ph.COastro-ph.HEhep-phApJ(2020)·8 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.