Mon·May 27, 2019Monday·May 27, 2019

1. 01*

   The Lifetime Frontier: Search for New Physics with Long-Lived Particles

   P. Q. Hung🇺🇸

   The search for new physics with long-lived particles is an ongoing and thriving effort in the High Energy Physics community which necessitates new search strategies such as novel algorithms, novel detectors, etc...For these reasons, one could perhaps add another frontier, the Lifetime Frontier, to the standard three (Energy, Intensity and Cosmic). In this talk, I will describe a BSM physics model whose characteristic signatures are decays of new (mirror) fermions at displaced vertices, a domain belonging to the Lifetime Frontier. It is a model of {\em non-sterile} right-handed neutrinos whose masses are proportional to the electroweak scale ${\Lambda }_{EW}\sim 246GeV$. The model proposed a solution to the strong CP problem with a surprising connection between the sizes of the neutrino masses and the $\theta$-angle which contributes to the neutron electric dipole moment.

   hep-ph4 citations
2. 02*

   Forward-backward asymmetry in the gauge-Higgs unification at the International Linear Collider

   Shuichiro Funatsu🇨🇳

   The signals of the SO(5) \times U(1) gauge-Higgs unification model at the International Linear Collider are studied. In this model, Kaluza-Klein modes of the neutral gauge bosons affect fermion pair productions. The deviations of the forward-backward asymmetries of the $e^{+}{e}^{-}\to \bar{b}b$, $\bar{t}t$ processes from the standard model predictions are clearly seen by using polarised beams. The deviations of these values are predicted for two cases, the bulk mass parameters of quarks are positive and negative case.

   hep-phEPJC(2019)·16 citations
3. 03*

   Axions and Atomic Clocks

   Lawrence M. Krauss (The Origins Project Foundation)🇺🇸

   The equations of electrodynamics are altered in the presence of a classical coherent axion dark matter background field, changing the dispersion relation for electromagnetic waves. Careful measurements of the frequency stability in sensitive atomic clocks could in principle provide evidence for such a background for $f_a\ge 10^7$ GeV. Turning on a background magnetic field might enhance these effects in a controllable way, and interferometric measurements might also be useful for probing the time-varying photon dispersion relation that results from a coherent cosmic axion background.

   hep-phastro-ph.COhep-exquant-ph5 citations
4. 04*

   A Study of Stress-Tensor Distribution around Flux Tube in Abelian-Higgs Model

   Ryosuke Yanagihara🇯🇵 · Masakiyo Kitazawa🇯🇵

   We study the stress-tensor distribution around the flux tube in static quark and anti-quark systems based on the momentum conservation and the Abelian-Higgs (AH) model. We first investigate constraints on the stress-tensor distribution from the momentum conservation and show that the effect of boundaries plays a crucial role to describe the structure of the flux tube in SU(3) Yang-Mills theory which has measured recently on the lattice. We then study the distributions of the stress tensor and energy density around the magnetic vortex with and without boundaries in the AH model, and compare them with the distributions in SU(3) Yang-Mills theory based on the dual superconductor picture. It is shown that a wide parameter range of the AH model is excluded by a comparison with the lattice results in terms of the stress tensor.

   hep-phhep-latnucl-thPTEP(2019)·22 citations
5. 05*

   LHC Constraints on a $(B-L{)}_3$ Gauge Boson

   Fatemeh Elahi🇮🇷 · Adam Martin🇺🇸

   In this paper, we explore the constraints that the LHC can place on a massive gauge boson $X$ that predominantly couples to the third generation of fermions. Such a gauge boson arises in scenarios where the $B-L$ of the third generation is gauged. We focus on the mass range $10\le m_X\lesssim 2m_W$, where current constraints are lacking, and develop a dedicated search strategy. For this mass range, we show that $b\bar{b}{\tau }^{+}{\tau }^{-}$, where at least one of the $\tau$s decay leptonically is the optimal channel to look for the $X$ at the LHC. The QCD production of $b$ quarks, combined with the cleanliness of the leptons coming from the decay of the $\tau$ allow us to detect $X$ gauge boson with couplings of $g_X\sim (0.005-0.01)$, for $m_X<50\text{GeV}$, and a coupling of $O(0.1)$ for heavier $X$ gauge boson with $100{\text{fb}}^{-1}$ of integrated luminosity. This is about a factor of 2-10 improvement over previous constraints coming from the decay of ${\rm Y}\to {\tau }^{+}{\tau }^{-}$. Extrapolating to the full HL-LHC luminosity of $3000{\text{fb}}^{-1}$, the bounds on $g_X$ can be enhanced by another factor of $\sqrt{2}$ for $m_X<50\text{GeV}$.

   hep-phPRD(2019)·11 citations
6. 06*

   Multicomponent Dark Matter in the Light of CALET and DAMPE

   Chao-Qiang Geng🇨🇳 · Da Huang🇵🇱 · Lu Yin🇹🇼

   In the light of the latest measurements on the total $e^{+}+e^{-}$ flux by CALET and DAMPE experiments, we revisit the multicomponent leptonically decaying dark matter (DM) explanations to the cosmic-ray electron/positron excesses observed previously. Especially, we use the single and double-component DM models to explore the compatibility of the AMS-02 positron fraction with the new CALET or DAMPE data. It turns out that neither single nor double-component DM models are able to fit the AMS-02 positron fraction and DAMPE total $e^{+}+e^{-}$ flux data simultaneously. On the other hand, for the combined AMS-02 and CALET dataset, both the single and double-component DM models can provide reasonable fits. If we further take into the diffuse $\gamma$-ray constraints from Fermi-LAT, only the double-component DM models are allowed.

   hep-phastro-ph.HENPB(2020)·3 citations
7. 07*

   Relic neutrino detection through angular correlations in inverse $\beta$-decay

   Evgeny Akhmedov🇩🇪

   Neutrino capture on beta-decaying nuclei is currently the only known potentially viable method of detection of cosmic background neutrinos. It is based on the idea of separation of the spectra of electrons or positrons produced in captures of relic neutrinos on unstable nuclei from those from the usual $\beta$-decay and requires very high energy resolution of the detector, comparable to the neutrino mass. In this paper we suggest an alternative method of discrimination between neutrino capture and $\beta$-decay, based on periodic variations of angular correlations in inverse beta decay transitions induced by relic neutrino capture. The time variations are expected to arise due to the peculiar motion of the Sun with respect to the C$\nu$B rest frame and the rotation of the Earth about its axis and can be observed in experiments with both polarized and unpolarized nuclear targets. The main advantage of the suggested method is that it does not depend crucially on the energy resolution of detection of the produced $\beta$-particles and can be operative even if this resolution exceeds the largest neutrino mass.

   hep-phastro-ph.COhep-exnucl-exJCAP(2019)·21 citations
8. 08*

   Lepton mass effects for beam-normal single-spin asymmetry in elastic muon-proton scattering

   Oleksandr Koshchii🇩🇪 · Andrei Afanasev🇺🇸

   We estimate the beam-normal single-spin asymmetry in elastic lepton-proton scattering without employing the ultrarelativistic approximation. Our calculation is relevant for analyses of muon scattering at energies of few hundred MeV and below -- when effects of the muon mass become essential. At such energies, the transverse polarization of the muon beam is expected to contribute significantly to the systematic uncertainty of precision measurements of elastic muon-proton scattering. We evaluate such systematics using an example of the MUSE experiment at PSI. The muon asymmetry is estimated at about 0.1\% in kinematics of MUSE and it is the largest for scattering into a backward hemisphere.

   hep-phPRD(2019)·10 citations
9. 09*

   Heavy Higgs Bosons at the LHC Upgrade

   Tong Li🇨🇳

   We evaluate the discovery potential for the heavy Higgs bosons at the LHC energy upgrade with $\sqrt{s}=27$ TeV. We take degenerate mass spectrum and assume near the alignment limit in the Type-II Two Higgs Doublet Model for illustration. We explore the observability of the heavy neutral Higgs bosons by examining the leading decay channel $H^0/A^0\to {\tau }^{+}{\tau }^{-}$ and the clean signals from $H^0\to W^{+}{W}^{-},ZZ$ via gluon-gluon fusion production. The associated production of a top quark and a charged Higgs boson via $gb\to t{H}^{\pm }$ is adopted to predict the discovery potential of heavy charged Higgses. We also emphasize the potential importance of the electroweak production of Higgs boson pairs, i.e. $pp\to W^{\ast }\to H^{\pm }{A}^0$ and $pp\to Z^{\ast }/{\gamma }^{\ast }\to H^{+}{H}^{-}$. They are only governed by pure electroweak gauge couplings and can provide complementary information to the conventional signals in the determination of the nature of the Higgs sector.

   hep-phCPC(2020)·0 citations
10. 10*

    Vacuum Instabilities in the N2HDM

    P.M. Ferreira🇵🇹 · Margarete Mühlleitner🇩🇪 · Rui Santos🇵🇹 · Georg Weiglein🇩🇪 · Jonas Wittbrodt🇩🇪

    The Higgs sector of the Next-to-Minimal Two-Higgs-Doublet Model (N2HDM) is obtained from the Two-Higgs-Doublet Model (2HDM) containing two complex Higgs doublets, by adding a real singlet field. In this paper, we analyse the vacuum structure of the N2HDM with respect to the possibility of vacuum instabilities. We show that while one type of charge- and CP-preserving vacuum cannot coexist with deeper charge- or CP-breaking minima, there is another type of vacuum whose stability is endangered by the possible occurrence of deeper charge- and CP-breaking minima. Analytical expressions relating the depth of different vacua are deduced. Parameter scans of the model are carried out that illustrate the regions of parameter space here the vacuum is either stable or metastable as well as the regions where tunnelling to deeper vacua gives rise to a too short lifetime of the vacuum. Taking other experimental and theoretical constraints into account, we find that the vacuum stability constraints have an important impact on the phenomenology of the N2HDM.

    hep-phJHEP(2019)·78 citations
11. 11*

    Enhanced $Z$ boson decays as a new probe of first-order electroweak phase transition at future lepton colliders

    Fa Peng Huang🇰🇷 · Eibun Senaha🇰🇷

    We study phenomenological consequences of the strong first-order electroweak phase transition in an extension of the standard model with an inert doublet and vector-like leptons motivated by the muon $g-2$ anomaly and dark matter. We find that a condition for the strong first-order electroweak phase transition inevitably induces a large logarithmic enhancement in $Z$ boson decays, which relegates the explanation of the anomalous muon $g-2$ at below 2$\sigma$ level. Our analysis shows that future lepton collider experiments, especially the Giga-$Z$ at the International Linear Collider and Tera-$Z$ at the Circular Electron Positron Collider as well as Future Circular Collider have great capability to explore the nature of the electroweak phase transition, which is complementary to conventional approaches via measurements of the triple Higgs boson coupling and gravitational waves.

    hep-phPRD(2019)·9 citations
12. 12*

    Exploring light supersymmetry with GAMBIT

    Anders Kvellestad (for the GAMBIT Collaboration)🇬🇧

    I summarize a recent study by the GAMBIT Collaboration in which we investigated the combined collider constraints on the chargino and neutralino sector of the Minimal Supersymmetric Standard Model. Through a large fit using GAMBIT we found that current ATLAS and CMS results with 36 fb${}^{-1}$ of 13 TeV LHC collision data do not provide a general constraint on the lightest neutralino and chargino masses. Further, we found that a pattern of excesses in some of the LHC analyses can be fit in a subset of the model parameter space. The excess has an estimated local significance of 3.3$\sigma$ based on the 13 TeV results alone, and 2.9$\sigma$ when 13 TeV and 8 TeV results are combined.

    hep-ph1 citation
13. 13*

    Naturalising the Third Family Hypercharge Model for Neutral Current $B-$Anomalies

    B. C. Allanach🇬🇧 · Joe Davighi🇬🇧

    We consider a deformation of the Third Family Hypercharge Model, which arguably makes the model more natural. Additional non-zero charges of the spontaneously broken, family-dependent $U(1{)}_F$ gauge symmetry are assigned to the second family leptons, and the third family leptons' charges are deformed away from their hypercharges in such a way that the $U(1{)}_F$ gauge symmetry remains anomaly-free. Second family $U(1{)}_F$ lepton charges allow a $Z^{\prime }$ coupling to muons without having to assume large charged lepton mixing, which risks violating tight lepton flavour violation bounds. In this deformed version, only the bottom and top Yukawa couplings are generated at the renormalisable level, whereas the tauon Yukawa coupling is absent. The $Z^{\prime }$ mediates a beyond the Standard Model contribution to an effective $(\bar{b}s)(\bar{\mu }\mu )$ vertex in the combination $C_9=-9C_{10}$ and is able to fit the apparent discrepancy between Standard Model predictions in flavour changing neutral-current $B-$meson decays and their measurements, whilst simultaneously avoiding current constraints from direct $Z^{\prime }$ searches and other measurements, when $1.2\text{TeV}<M_{Z^{\prime }}<12.5\text{TeV}$.

    hep-phhep-exEPJC(2019)·55 citations
14. 14*

    Canonical interpretation of $Y(10750)$ and ${\rm Y}(10860)$ in the ${\rm Y}$ family

    Qi Li🇨🇳 · Ming-Sheng Liu🇨🇳 · Qi-Fang Lü🇨🇳 · Long-Cheng Gui🇨🇳 · Xian-Hui Zhong🇨🇳

    Inspired by the new resonance $Y(10750)$, we calculate the masses and two-body OZI-allowed strong decays of the higher vector bottomonium sates within both screened and linear potential models. We discuss the possibilities of ${\rm Y}(10860)$ and $Y(10750)$ as mixed states via the $S-D$ mixing. Our results suggest that $Y(10750)$ and ${\rm Y}(10860)$ might be explained as mixed states between $5S$- and $4D$-wave vector $b\bar{b}$ states. The $Y(10750)$ and ${\rm Y}(10860)$ resonances may correspond to the mixed states dominated by the $4D$- and $5S$-wave components, respectively. The mass and the strong decay behaviors of the ${\rm Y}(11020)$ resonance are consistent with the assignment of the ${\rm Y}(6S)$ state in the potential models.

    hep-phhep-exnucl-thEPJC(2020)·36 citations
15. 15*

    Looking at the axionic dark sector with ANITA

    Ivan Esteban🇪🇸 · Jacobo Lopez-Pavon🇪🇸 · Ivan Martinez-Soler🇺🇸 · Jordi Salvado🇪🇸

    The ANITA experiment has recently observed two anomalous events emerging from well below the horizon. Even though they are consistent with tau cascades, a high energy Standard Model or Beyond the Standard Model explanation is challenging and in tension with other experiments. We study under which conditions the reflection of generic radio pulses can reproduce these signals. We propose that these pulses can be resonantly produced in the ionosphere via axion-photon conversion. This naturally explains the direction and polarization of the events and avoids other experimental bounds.

    hep-phastro-ph.HEhep-exEPJC(2020)·33 citations
16. 16*

    Adversarially-trained autoencoders for robust unsupervised new physics searches

    Andrew Blance🇬🇧 · Michael Spannowsky🇬🇧 · Philip Waite🇬🇧

    Machine learning techniques in particle physics are most powerful when they are trained directly on data, to avoid sensitivity to theoretical uncertainties or an underlying bias on the expected signal. To be able to train on data in searches for new physics, anomaly detection methods are imperative, which can be realised by an autoencoder acting as an unsupervised classifier. The last source of uncertainties affecting the classifier are then experimental uncertainties in the reconstruction of the final-state objects. To mitigate their effect on the classifier and to allow for a realistic assessment of the method, we propose to combine the autoencoder with an adversarial neural network to remove its sensitivity to the smearing of the final-state objects. We quantify its effect and show that one can achieve a robust anomaly detection in resonance-induced $t\bar{t}$ final states.

    hep-phJHEP(2019)·138 citations
17. 17*

    Strong coupling constants and radiative decays of the heavy tensor mesons

    Guo Liang Yu🇨🇳 · Zhi Gang Wang🇨🇳 · Zhen Yu Li🇨🇳

    In this article, we analyze tensor-vector-pseudoscalar(TVP) type of vertices $D_2^{\ast +}{D}^{+}\rho$, $D_2^{\ast 0}{D}^0\rho$, $D_2^{\ast +}{D}^{+}\omega$, $D_2^{\ast 0}{D}^0\omega$, $B_2^{\ast +}{B}^{+}\rho$, $B_2^{\ast 0}{B}^0\rho$, $B_2^{\ast +}{B}^{+}\omega$, $B_2^{\ast 0}{B}^0\omega$, $B_{s2}^{\ast }{B}_s\varphi$ and $D_{s2}^{\ast }{D}_s\varphi$, in the frame work of three point QCD sum rules. According to these analysis, we calculate their strong form factors which are used to fit into analytical functions of $Q^2$. Then, we obtain the strong coupling constants by extrapolating these strong form factors into deep time-like regions. As an application of this work, the coupling constants for radiative decays of these heavy tensor mesons are also calculated at the point of $Q^2=0$. With these coupling constants, we finally calculate the radiative decay widths of these tensor mesons.

    hep-phEPJC(2019)·13 citations
18. 18*

    Symmetries in the SME gravity sector: A study in the first-order formalism

    Y. Bonder🇲🇽 · C. Corral🇲🇽

    A method to find the symmetries of a theory in the first order formalism of gravity is presented. This method is applied to the minimal gravity sector of the Standard Model Extension. It is argued that no inconsistencies arise when Lorentz violation is explicit and the relation between Lorentz violation and invariance under (active) diffeomorphisms is clearly exposed.

    ↳ gr-qchep-ph2 citations
19. 19*

    Anatomy of a thermal black hole mimicker

    Jing Ren🇨🇳

    We are entering a new era to test the strong gravity regime around astrophysical black holes. The possibility that they are actually horizonless ultracompact objects and then free from the information loss paradox can be examined more closely with observational data. In this paper, we systematically develop a thermal gas model of the 2-2-hole in quadratic gravity, as one step further to look for more tractable models of black hole mimickers. Concrete predictions for departures from black holes are made all the way down to the high curvature interior. The simple form of matter further enables an explicit study of the relation between geometry and thermodynamics. Within this unified framework, we identify notably different behaviors at two limits. On one side is the astrophysically large 2-2-hole, as characterized by a minuscule deviation outside the would-be horizon and a highly squeezed interior along the radial direction. Anomalous features of black hole thermodynamics emerge from the ordinary gas. On the other side is the minimal 2-2-hole with an isotropic and shrinking interior, which behaves more like a normal thermodynamic system. This brings a new perspective to the related theoretical questions as well as phenomenological implications.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2019)·27 citations
20. 20*

    Precision Test of the Weak Equivalence Principle from Gamma-Ray Burst Polarization

    Jun-Jie Wei🇨🇳 · Xue-Feng Wu🇨🇳

    If the weak equivalence principle (WEP) is broken, the measured values of the parametrized post-Newtonian parameter $\gamma$ from photons with left- and right-handed circular polarizations should differ slightly, leading to the arrival-time difference of these two circular components. Thus, the polarization vector of a linearly polarized light may rotate during the propagation. The rotation angle of the polarization vector depends on both the photon energy and the distance of the source. It is believed that if the rotation angle differs by more than $\pi /2$ over an energy range, then the net polarization of the signal would be significantly suppressed and could not be as high as the observed level. Thus, the detection of highly polarized photons implies that the relative rotation angle ($\Delta \Theta$) should not be too large. In this paper, we give a detailed calculation on the evolution of gamma-ray burst (GRB) polarization arising from a possible violation of the WEP, and we find that more than $60\%$ of the initial polarization degree can be conserved even if $\Delta \Theta$ is larger than $\pi /2$. In addition, to tightly constrain the WEP violation, GRBs with harder spectra and polarization observations in a wider energy range seem to be favored. Applying our formulas to the measurements of linear polarization from GRB 110721A and GRB 061122, we obtain strict limits on the differences of the $\gamma$ values as low as $\Delta \gamma <1.3\times 10^{-33}$ and $\Delta \gamma <0.8\times 10^{-33}$. These provide the most stringent limits to date on a deviation from the WEP, improving at least 6 orders of magnitude over previous bounds.

    ↳ astro-ph.HEgr-qchep-phhep-thPRD(2019)·9 citations
21. 21*

    A counter-top search for macroscopic dark matter

    Jagjit Singh Sidhu🇺🇸 · Glenn Starkman🇺🇸 · Ralph Harvey🇺🇸

    A number of dark matter candidates have been discussed that are macroscopic, of approximately nuclear density, and scatter ordinary matter essentially elastically with approximately their geometric cross-section. A wide range of mass and geometric cross-section is still unprobed for these "macros." Macros passing through rock would melt the material in cylinders surrounding their long nearly straight trajectories. Once cooled, the resolidified rock would be easily distinguishable from its surroundings. We discuss how, by visually examining ordinary slabs of rock such as are widely available commercially for kitchen countertops, one could probe an interesting segment of the open macro parameter space.

    ↳ astro-ph.HEastro-ph.COhep-phPRD(2019)·24 citations
22. 22*

    Heavy baryon spectroscopy from lattice QCD

    M. Padmanath🇩🇪

    In this report, the most recent and precise estimates of masses of ground state baryons using lattice QCD are discussed. Considering the prospects in the heavy baryon sector, lattice estimates for these are emphasized. The first and only existing lattice determination of the highly excited ${\Omega }_c$ excitations in relation to the recent LHCb discovery is also discussed.

    ↳ hep-lathep-exhep-ph15 citations
23. 23*

    Pion scattering in the isospin I=2 channel from elongated lattices

    C. Culver🇺🇸 · M. Mai🇺🇸 · A. Alexandru🇺🇸 · M. Doring🇺🇸 · F. X. Lee🇺🇸

    Pion-pion elastic scattering in the isospin I=2 channel is investigated in two-flavor dynamical lattice QCD. Six ensembles are used with lattices elongated in one of the spatial dimensions at two quark masses corresponding to a pion mass of 315 MeV and 226 MeV. The energy of the low-lying states below the inelastic threshold are extracted in each case using the standard variational method.The extracted finite-volume spectrum is fitted by the inverse amplitude method simultaneously for both quark masses and extrapolated thereafter to the physical point. The resulting phase-shifts and scattering length are compared with those from experiment, leading-order chiral perturbation theory and other lattice studies. Our calculations match the experimental results.

    ↳ hep-lathep-phnucl-thPRD(2019)·47 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.