Wed·Jan 27, 2021Wednesday·January 27, 2021

1. 01*

   A natural and simple UV completion of the QCD axion model

   Masaki Yamada🇯🇵 · Tsutomu T. Yanagida🇨🇳

   The novel PQ mechanism replaces the strong CP problem with some challenges in a model building. In particular, the challenges arise regarding i) the origin of an anomalous global symmetry called a PQ symmetry, ii) the scale of the PQ symmetry breaking, and iii) the quality of the PQ symmetry. In this letter, we provide a natural and simple UV completed model that addresses these challenges. Extra quarks and anti-quarks are separated by two branes in the Randall-Sundrum ${\mathbf{R}}^4\times S^1/{\mathbf{Z}}_2$ spacetime while a hidden SU($N_H$) gauge field condensates in the bulk. The brane separation is the origin of the PQ symmetry and its breaking scale is given by the dynamical scale of the SU($N_H$) gauge interaction. The (generalized) Casimir force of SU($N_H$) condensation stabilizes the 5th dimension, which guarantees the quality of the PQ symmetry.

   hep-phgr-qchep-thPLB(2021)·18 citations
2. 02*

   Probing electroweak phase transition with multi-TeV muon colliders and gravitational waves

   Wei Liu🇨🇳 · Ke-Pan Xie🇰🇷

   We study the complementarity of the proposed multi-TeV muon colliders and the near-future gravitational wave (GW) detectors to the first order electroweak phase transition (FOEWPT), taking the real scalar extended Standard Model as the representative model. A detailed collider simulation shows the FOEWPT parameter space can be greatly probed via the the vector boson fusion production of the singlet, and its subsequent decay to the di-Higgs or di-boson channels. Especially, almost all the parameter space yielding detectable GW signals can be probed by the muon colliders. Therefore, if we could detect stochastic GWs in the future, a muon collider could provide a hopeful crosscheck to identify their origin. On the other hand, there is considerable parameter space that escapes GW detections but is within the reach of the muon colliders. The precision measurements of Higgs couplings could also probe the FOEWPT parameter space efficiently.

   hep-phJHEP(2021)·88 citations
3. 03*

   Neutrino non-standard interactions meet precision measurements of $N_{\mathrm{eff}}$

   Yong Du🇨🇳 · Jiang-Hao Yu🇨🇳

   The number of relativistic species, $N_{\mathrm{eff}}$, has been precisely calculated in the standard model, and would be measured to the percent level by CMB-S4 in future. Neutral-current non-standard interactions would affect neutrino decoupling in the early Universe, thus modifying $N_{\mathrm{eff}}$. We parameterize those operators up to dimension-7 in the effective field theory framework, and then provide a complete, generic and analytical dictionary for the collision term integrals. From precision measurements of $N_{\mathrm{eff}}$, the most stringent constraint is obtained for the dimension-6 vector-type neutrino-electron operator, whose scale is constrained to be above about 195 (331) GeV from Planck (CMB-S4). We find our results complementary to other experiments like neutrino coherent scattering, neutrino oscillation, collider, and neutrino deep inelastic scattering experiments.

   hep-phastro-ph.COastro-ph.HEJHEP(2021)·44 citations
4. 04*

   Physics potential of a muon-proton collider

   Kingman Cheung🇹🇼 · Zeren Simon Wang🇹🇼

   We propose a muon-proton collider with asymmetrical multi-TeV beam energies and integrated luminosities of $0.1-1$ ab${}^{-1}$. With its large center-of-mass energies and yet small Standard Model background, such a machine can not only improve electroweak precision measurements but also probe new physics beyond the Standard Model to an unprecedented level. We study its potential in measuring the Higgs properties, probing the R-parity-violating Supersymmetry, as well as testing heavy new physics in the muon $g-2$ anomaly. We find that for these physics cases the muon-proton collider can perform better than both the ongoing and future high-energy collider experiments.

   hep-phPRD(2021)·27 citations
5. 05*

   System size dependence of baryon-strangeness correlations in relativistic heavy ion collisions from a multiphase transport model

   D. F. Wang🇨🇳 · S. Zhang🇨🇳 · Y. G. Ma🇨🇳

   The system size dependence of baryon-strangeness (BS) correlations ($C_{BS}$) are investigated with a multiphase transport (AMPT) model for various collision systems from ${}^{10}\mathrm{B}{+}^{10}\mathrm{B}$, ${}^{12}\mathrm{C}{+}^{12}\mathrm{C}$, ${}^{16}\mathrm{O}{+}^{16}\mathrm{O}$, ${}^{20}\mathrm{Ne}{+}^{20}\mathrm{Ne}$, ${}^{40}\mathrm{Ca}{+}^{40}\mathrm{Ca}$, ${}^{96}\mathrm{Zr}{+}^{96}\mathrm{Zr}$, and ${}^{197}\mathrm{Au}{+}^{197}\mathrm{Au}$ at RHIC energies $\sqrt{s_{NN}}$ of 200, 39, 27, 20, and 7.7 GeV. Both effects of hadron rescattering and a combination of different hadrons play a leading role for baryon-strangeness correlations. When the kinetic window is limited to absolute rapidity $|y|>3$, these correlations tend to be constant after the final-state interaction whatever kind of hadrons subset we chose based on the AMPT framework. The correlation is found to smoothly increase with baryon chemical potential ${\mu }_B$, corresponding to the collision system or energy from the quark-gluon-plasma-like phase to the hadron-gas-like phase. Besides, the influence of initial nuclear geometrical structures of $\alpha$-clustered nuclear collision systems of ${}^{12}\mathrm{C}{+}^{12}\mathrm{C}$ as well as ${}^{16}\mathrm{O}{+}^{16}\mathrm{O}$ collisions is discussed but the effect is found negligible. The current model studies provide baselines for searching for the signals of Quantum Chromodynamics (QCD) phase transition and critical point in heavy-ion collisions through the BS correlation.

   hep-phnucl-thPRC(2021)·6 citations
6. 06*

   The study of ${\eta }_c(1S)$ $\to$ $P{P}^{\prime }$ decays

   Yueling Yang🇨🇳 · Xule Zhao🇨🇳 · Shuangshi Fang🇨🇳 · Jinshu Huang🇨🇳 · Junfeng Sun🇨🇳

   The ${\eta }_c(1S)$ $\to$ $P{P}^{\prime }$ decays are the parity violation modes. These decays can be induced by the weak interactions within the standard model, and have been searched for based on the available experimental data. To meet the needs of experimental investigation, the ${\eta }_c(1S)$ $\to$ $P{P}^{\prime }$ decays are studied with the perturbative QCD approach. It is found that branching ratios are the order of $10^{-15}$ and less, which offers a ready reference for future analyses.

   hep-phhep-exPhysics(2021)·1 citation
7. 07*

   Strong decays of the newly $P_{cs}(4459)$ as a strange hidden-charm ${\Xi }_c{\bar{D}}^{\ast }$ molecule

   Rui Chen🇨🇳

   In our former work [arXiv:2011.07214], the $P_{cs}(4459)$ observed by the LHCb Collaboration can be explained as a coupled strange hidden-charm ${\Xi }_c{\bar{D}}^{\ast }/{\Xi }_c^{\ast }\bar{D}/{\Xi }_c^{\prime }{\bar{D}}^{\ast }/{\Xi }_c^{\ast }{\bar{D}}^{\ast }$ molecule with $I(J^P)=0(3/2^{-})$. Here, we further discuss the two-body strong decay behaviors of the $P_{cs}(4459)$ in the meson-baryon molecular scenario by input the former obtained bound solutions. Our results support the $P_{cs}(4459)$ as the strange hidden-charm ${\Xi }_c{\bar{D}}^{\ast }$ molecule with $I(J^P)=0(3/2^{-})$. The relative decay ratio between ${\Lambda }_c{D}_s^{\ast }$ and $J/\psi \Lambda$ is around 10, where the partial decay width for the ${\Lambda }_c{D}_s^{\ast }$ channel is around 0.6 to 2.0 MeV.

   hep-phEPJC(2021)·52 citations
8. 08*

   Triangle relations for XYZ states

   Kai Zhu🇨🇳

   We propose novel triangle relations, not the well-known triangle singularity, for better understanding of the exotic XYZ states. Nine XYZ resonances, X(3872), Y(4230), Zc(3900), X(4012), Y(4360/4390), Zc(4020), X(4274), Y(4660), and Zcs(3985) have been classified into triples to construct three triangles based on the assumption that they are all tetra-quark states. We also suggest some channels deserving search for with high priority based on this hypothesis, as well as predictions of a few production/decay rates of these channels. We hope further experimental studies of the XYZ states will benefit from our results.

   hep-phhep-exInt.J.Mod.Phys.A(2021)·17 citations
9. 09*

   Non-Gaussianity from $X,Y$ gauge bosons in Cosmological Collider Physics

   Nobuhito Maru🇯🇵 · Akira Okawa🇯🇵

   Heavy fields of Hubble scale order present during inflation contribute to the non-Gaussian signature for the three-point function of the inflaton. Taking into account that Hubble scale is around the scale of grand unified theory (GUT), this opens a possibility that the GUT scale signatures, which are very hard to be discovered at collider, might be detectable by using information from the precise observations of cosmic microwave background. We discuss a detactability of the $X,Y$ gauge boson present in any GUT in a framework of cosmological collider physics. Calculating one-loop contributions of $X,Y$ gauge bosons to the inflaton three-point functions, we find a remarkable result that one-loop diagram with interactions originated from the mass terms of $X,Y$ gauge bosons provides an enhancement factor expressed by the ratio between the $X,Y$ gauge boson mass and Hubble scale as $(m_X/H{)}^4$. In an estimation of the non-Gaussianity, this factor is crucial and its impact on the detactability of $X,Y$ gauge bosons is discussed.

   hep-phastro-ph.COgr-qchep-th39 citations
10. 10*

    Electromagnetic transitions of the singly charmed baryons with spin 3/2

    June-Young Kim🇩🇪 · Hyun-Chul Kim🇰🇷 · Ghil-Seok Yang🇰🇷 · Makoto Oka🇯🇵

    We investigate the electromagnetic transitions of the singly charmed baryons with spin 3/2, based on a pion mean-field approach, also known as the chiral quark-soliton model, taking into account the rotational $1/N_c$ corrections and the effects of flavor SU(3) symmetry breaking. We examine the valence- and sea-quark contributions to the electromagnetic transition form factors and find that the quadrupole form factors of the sea-quark contributions dominate over those of the valence-quark ones in the smaller $Q^2$ region, whereas the sea quarks only provide marginal contributions to the magnetic dipole transition form factors of the baryon sextet with spin 3/2. The effects of the flavor SU(3) symmetry breaking are in general very small except for the forbidden transition ${\Xi }_c^0\gamma \to {\Xi }_c^{\ast 0}$ by $U$-spin symmetry. We also discuss the widths of the radiative decays for the baryon sextet with spin 3/2, comparing the present results with those from other works.

    hep-phhep-latPRD(2021)·35 citations
11. 11*

    Probing non-standard $b\bar{b}h$ interaction at the LHC at $\sqrt{s}=13$ TeV

    Partha Konar🇮🇳 · Biswarup Mukhopadhyaya🇮🇳 · Rafiqul Rahaman🇮🇳 · Ritesh K. Singh🇮🇳

    In the detailed probe of Higgs boson properties at the Large Hadron Collider, and in looking for new physics signatures in the electroweak symmetry breaking sector, the bottom quark Yukawa coupling has a crucial role. We investigate possible departure from the standard model value of $b\bar{b}h$ coupling, phenomenologically expressed in terms of a modification factor ${\alpha }_b$, in $b\bar{b}$-associated production of the $125$-GeV scalar at the high-luminosity LHC. In a next-to-leading order estimate, we make use of a gradient boosting algorithm to improve in statistical significance upon a cut-based analysis. It is found possible to probe down to ${\alpha }_b=3$ with more than $5\sigma$ significance, with $\mathcal{L}=3000$ fb${}^{-1}$ and $\sqrt{s}$ = 13 TeV, while the achievable limit at $95\%$ C.L. is $\pm 1.95$.

    hep-phhep-exPLB(2021)·6 citations
12. 12*

    Screening the Higgs portal

    Philippe Brax🇫🇷 · Clare Burrage🇬🇧

    Light scalar fields that couple to matter through the Higgs portal mediate long range fifth forces. We show how the mixing of a light scalar with the Higgs field can lead to this fifth force being screened around macroscopic objects. This behaviour can only be seen by considering both scalar fields as dynamical, and is missed if the mixing between the Higgs field and the scalar field is not taken into account. We explain under which conditions the naive "integrating out" procedure fails, i.e. when the mass matrix of the Higgs-scalars system has a nearly vanishing mass eigenvalue. The resulting flat direction in field space can be lifted at the quadratic order in the presence of matter and the resulting fifth force mediated by the Higgs portal can be screened either when the gravitating objects are large enough or their surface Newton potential exceeds a threshold. Finally we discuss the implications of these results for nearly massless relaxion models.

    hep-phastro-ph.COhep-thPRD(2021)·13 citations
13. 13*

    Coloured Scalars Mediated Rare Charm Meson Decays to Invisible Fermions

    Svjetlana Fajfer🇸🇮 · Anja Novosel🇸🇮

    We consider effects of coloured scalar mediators in decays $c\to uinvisibles$. In particular, in these processes, as invisibles, we consider massive right-handed fermions. The coloured scalar ${\bar{S}}_1\equiv (\bar{3},1,-2/3)$, due to its coupling to weak singlets up-quarks and invisible right-handed fermions ($\chi$), is particularly interesting. Then, we consider ${\tilde{R}}_2\equiv (\bar{3},2,1/6)$, which as a weak doublet is a subject of severe low-energy constraints. The $\chi$ mass is considered in the range $(m_K-m_{\pi })/2\le m_{\chi }\le (m_D-m_{\pi })/2$. We determine branching ratios for $D\to \chi \bar{\chi }$, $D\to \chi \bar{\chi }\gamma$ and $D\to \pi \chi \chi$ for several $\chi$ masses, using most constraining bounds. For ${\bar{S}}_1$, the most constraining is $D^0-{\bar{D}}^0$ mixing, while in the case of ${\tilde{R}}_2$ the strongest constraint comes from $B\to Kmissingenergy$ . We find in decays mediated by ${\bar{S}}_1$ that branching ratios can be $\mathcal{B}(D\to \chi \bar{\chi })<10^{-8}$ for $m_{\chi }=0.8$ GeV, $\mathcal{B}(D\to \chi \bar{\chi }\gamma )\sim 10^{-8}$ for $m_{\chi }=0.18$ GeV, while $\mathcal{B}(D^{+}\to {\pi }^{+}\chi \bar{\chi })$ can reach $\sim 10^{-8}$ for $m_{\chi }=0.18$ GeV. In the case of ${\tilde{R}}_2$ these decay rates are very suppressed. We find that future tau-charm factories and Belle II experiments offer good opportunities to search for such processes. Both ${\bar{S}}_1$ and ${\tilde{R}}_2$ might have masses within LHC reach.

    hep-phhep-exPRD(2021)·19 citations
14. 14*

    Weak Kaon Production off the nucleon and Watson's theorem

    E. Saul-Sala🇪🇸 · J. E. Sobczyk🇩🇪 · M. Rafi Alam🇮🇳 · L. Alvarez-Ruso🇪🇸 · J. Nieves🇪🇸

    We have improved the tree-level model of Ref arXiv:1004.5484 [hep-ph] for weak production of kaons off nucleons by partially restoring unitarity. This is achieved by imposing Watson's theorem to the dominant vector and axial-vector contributions in appropriate angular momentum and isospin quantum number sectors. The observable consequences of this procedure are investigated.

    hep-phhep-exnucl-exnucl-thPLB(2021)·2 citations
15. 15*

    Universal behavior of mass gaps existing in the single heavy baryon family

    Bing Chen🇨🇳 · Si-Qiang Luo🇨🇳 · Xiang Liu🇨🇳

    The mass gaps existing in the discovered single heavy flavor baryons are analyzed, which show some universal behaviors. Under the framework of a constituent quark model, we quantitatively explain why such interesting phenomenon happens, when these established excited heavy baryons are regarded as the $\lambda$-mode excitations. Based on the universal behaviors of the discussed mass gaps, we may have three implications including the prediction of the masses of excited ${\Xi }_b^0$ baryons which are still missing in the experiment. For completeness, we also discuss the mass gaps of these $\rho$-mode excited single heavy flavor baryons.

    hep-phEPJC(2021)·27 citations
16. 16*

    Vortex rings from high energy central p+A collisions

    Michael Annan Lisa🇺🇸 · João Guilherme Prado Barbon🇧🇷 · David Dobrigkeit Chinellato🇧🇷 · Willian Matioli Serenone🇧🇷 · Chun Shen🇺🇸 · Jun Takahashi🇧🇷 · Giorgio Torrieri🇧🇷

    Relativistic p+A collisions may produce droplets of quark gluon plasma (QGP) that quickly develop a toroidal vortex structure similar to that of an expanding smoke ring. We present viscous relativistic hydrodynamic calculations of ultra-central p+A collisions and develop an experimental observable to probe the structure, correlating the polarization and momentum of hyperons emitted from the collision. The effect is robust against changes in the definition of vorticity used to calculate the polarization. Experiments at RHIC and LHC may test the existence and strength of the vortex toroids, bringing new evidence to bear on the question of collectivity in the smallest QGP droplets.

    hep-phPRC(2021)·35 citations
17. 17*

    The Gross-Llewellyn Smith sum rule up to $\mathcal{O}({\alpha }_s^4)$-order QCD corrections

    Xu-Dong Huang🇨🇳 · Xing-Gang Wu🇨🇳 · Qing Yu🇨🇳 · Xu-Chang Zheng🇨🇳 · Jun Zeng🇨🇳

    In the paper, we analyze the properties of Gross-Llewellyn Smith (GLS) sum rule by using the $\mathcal{O}({\alpha }_s^4)$-order QCD corrections with the help of principle of maximum conformality (PMC). By using the PMC single-scale approach, we obtain an accurate renormalization scale-and-scheme independent fixed-order pQCD contribution for GLS sum rule, e.g. $S^{\mathrm{GLS}}(Q_0^2=3{\mathrm{GeV}}^2){|}_{\mathrm{PMC}}=2.559_{-0.024}^{+0.023}$, where the error is squared average of those from $\Delta {\alpha }_s(M_Z)$, the predicted $\mathcal{O}({\alpha }_s^5)$-order terms predicted by using the Padé approximation approach. After applying the PMC, a more convergent pQCD series has been obtained, and the contributions from the unknown higher-order terms are highly suppressed. In combination with the nonperturbative high-twist contribution, our final prediction of GLS sum rule agrees well with the experimental data given by the CCFR collaboration.

    hep-phNPB(2021)·7 citations
18. 18*

    Scrutinizing new physics of $B_d\to \varphi ({\eta }^{{(}^{\prime })},\pi ,\omega )$ decay modes

    Manas K. Mohapatra (IIT Hyderabad, Kandi)🇮🇳

    We inspect the exclusive hadronic decay modes $B_d\to \varphi ({\eta }^{{(}^{\prime })},\pi ,\omega )$, induced by quark level transition as $b\to d$ $(\Delta S=0)$, in vector like down quark model. As these decay modes insist highly suppressed followed by the predicted branching fraction $\mathcal{O}(10^{-9})$ which reflects to scrutinize physics beyond the standard model. We constrain the new parameter space inferred from experimental limits on leptonic $B_d\to \ell \ell (\ell =e,\mu ,\tau )$ and nonleptonic decay modes $B_d\to {\eta }^{\prime }{\pi }^0$ and $B_u\to {\rho }^{-}{\eta }^{\prime }$. We then check the new physics contributions can have significant impact on the prominent observable so called branching ratio of $B_d\to \varphi ({\eta }^{{(}^{\prime })},\pi ,\omega )$ processes.

    hep-phJ.Phys.G(2021)·1 citation
19. 19*

    Photon pair distributions and event-mixing at low invariant mass

    Mike Sas🇳🇱 · Lizette Lamers🇳🇱 · Thomas Peitzmann🇳🇱

    Neutral meson cross-section and direct photon HBT measurements in high energy pp, pA, and AA collisions rely on either subtracting or dividing out the background underlying the $M_{\mathrm{inv}}$ or $Q_{\mathrm{inv}}$ distributions. In this paper we investigate the photon pair distributions for simulated proton-proton collisions at $\sqrt{s}=13$TeV, and study why the background in $M_{\mathrm{inv}}$ gets poorly described by the conventional event-mixing method implemented in experimental analyses. We show that it fails to describe the background as it gives a qualitatively different shape especially at invariant masses around the ${\pi }^0$ and $\eta$ meson mass, which is mainly caused by the correlations originating from parton fragmentation.

    hep-phnucl-ex0 citations
20. 20*

    Observing Invisible Axions with Gravitational Waves

    Marco Gorghetto🇮🇱 · Edward Hardy🇬🇧 · Horia Nicolaescu🇬🇧

    If the Peccei-Quinn symmetry associated to an axion has ever been restored after inflation, axion strings inevitably produce a contribution to the stochastic gravitational wave background. Combining effective field theory analysis with numerical simulations, we show that the resulting gravitational wave spectrum has logarithmic deviations from a scale invariant form with an amplitude that is significantly enhanced at low frequencies. As a result, a single ultralight axion-like particle with a decay constant larger than $10^{14}\mathrm{GeV}$ and any mass between $10^{-18}\mathrm{eV}$ and $10^{-28}\mathrm{eV}$ leads to an observable gravitational wave spectrum and is compatible with constraints on the post-inflationary scenario from dark matter overproduction, isocurvature and dark radiation. Since the spectrum extends over a wide range of frequencies, the resulting signal could be detected by multiple experiments. We describe straightforward ways in which the Peccei-Quinn symmetry can be restored after inflation for such decay constants. We also comment on the recent possible NANOgrav signal in light of our results.

    hep-phastro-ph.COgr-qchep-thJCAP(2021)·134 citations
21. 21*

    Spillway Preheating

    JiJi Fan🇺🇸 · Kaloian D. Lozanov🇺🇸 · Qianshu Lu🇺🇸

    In traditional models only an order one fraction of energy is transferred from the inflaton to radiation through nonperturbative resonance production in preheating immediately after inflation, due to backreaction effects. We propose a particle production mechanism that could improve the depletion of the inflaton energy density by up to four orders of magnitude. The improvement comes from the fast perturbative decays of resonantly produced daughter particles. They act as a "spillway" to drain these daughter particles, reducing their backreaction on the inflaton and keeping the resonant production effective for a longer period. Thus we dub the scenario "spillway preheating". We also show that the fraction of energy density remaining in the inflaton has a simple inverse power-law scaling in the scenario. In general, spillway preheating is a much more efficient energy dissipation mechanism, which may have other applications in model building for particle physics.

    hep-phastro-ph.COJHEP(2021)·33 citations
22. 22*

    Twin Higgs Portal Dark Matter

    David Curtin🇨🇦 · Shayne Gryba🇨🇦

    Many minimal models of dark matter (DM) or canonical solutions to the hierarchy problem are either excluded or severely constrained by LHC and direct detection null results. In particular, Higgs Portal Dark Matter (HPDM) features a scalar coupling to the Higgs via a quartic interaction, and obtaining the measured relic density via thermal freeze-out gives definite direct detection predictions which are now almost entirely excluded. The Twin Higgs solves the little hierarchy problem without coloured top partners by introducing a twin sector related to the Standard Model (SM) by a discrete symmetry. We generalize HPDM to arbitrary Twin Higgs models and introduce Twin Higgs Portal Dark Matter (THPDM), which features a DM candidate with an $SU(4)$-invariant quartic coupling to the Twin Higgs scalar sector. Given the size of quadratic corrections to the DM mass, its most motivated scale is near the mass of the radial mode. In that case, DM annihilation proceeds with the full Twin Higgs portal coupling, while direct detection is suppressed by the pNGB nature of the 125 GeV Higgs. For a standard cosmological history, this results in a predicted direct detection signal for THPDM that is orders of magnitude below that of HPDM with very little dependence on the precise details of the twin sector, evading current bounds but predicting possible signals at next generation experiments. In many Twin Higgs models, twin radiation contributions to $\Delta N_{\mathrm{eff}}$ are suppressed by an asymmetric reheating mechanism. We study this by extending the $\nu$MTH and $X$MTH models to include THPDM and compute the viable parameter space according to the latest CMB bounds. The injected entropy dilutes the DM abundance as well, resulting in additional suppression of direct detection below the neutrino floor.

    hep-phJHEP(2021)·33 citations
23. 23*

    A convolutional-neural-network estimator of CMB constraints on dark matter energy injection

    Wei-Chih Huang🇩🇰 · Jui-Lin Kuo🇦🇹 · Yue-Lin Sming Tsai🇨🇳

    We show that the impact of energy injection by dark matter annihilation on the cosmic microwave background power spectra can be apprehended via a residual likelihood map. By resorting to convolutional neural networks that can fully discover the underlying pattern of the map, we propose a novel way of constraining dark matter annihilation based on the Planck 2018 data. We demonstrate that the trained neural network can efficiently predict the likelihood and accurately place bounds on the annihilation cross-section in a $\text{model-independent}$ fashion. The machinery will be made public in the near future.

    ↳ astro-ph.COhep-phJCAP(2021)·5 citations
24. 24*

    Hunting for Dark Matter and New Physics with GECCO

    Adam Coogan🇳🇱 · Alexander Moiseev🇺🇸 · Logan Morrison🇺🇸 · Stefano Profumo🇺🇸 · Matthew G. Baring🇺🇸 · Aleksey Bolotnikov🇺🇸 · Gabriella A. Carini🇺🇸 · Sven C. Herrmann🇺🇸 · Francesco Longo🇮🇹 · Floyd W. Stecker🇺🇸 · Alessandro Armando Vigliano🇮🇹 · Richard S. Woolf🇺🇸

    We outline the science opportunities in the areas of searches for dark matter and new physics offered by a proposed future MeV gamma-ray telescope, the Galactic Explorer with a Coded Aperture Mask Compton Telescope (GECCO). We point out that such an instrument would play a critical role in opening up a discovery window for particle dark matter with mass in the MeV or sub-MeV range, in disentangling the origin of the mysterious 511 keV line emission in the Galactic Center region, and in potentially discovering Hawking evaporation from light primordial black holes.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAastro-ph.IM+1PRD(2023)·44 citations
25. 25*

    On the Higher Loop Euler-Heisenberg Trans-Series Structure

    Gerald V. Dunne🇺🇸 · Zachary Harris🇺🇸

    We show that the one-loop Euler-Heisenberg QED effective Lagrangian in a constant background field acquires a very different non-perturbative trans-series structure at two-loop and higher-loop order in the fine structure constant. Beyond one-loop, virtual particles interact, causing fluctuations about the instantons, whereby the simple poles of the one-loop Borel transform become branch points. We illustrate this in detail at two-loop order using Ritus's seminal result for the renormalized two-loop effective Lagrangian as an exact double-integral representation, and propose a possible new approach to computations at higher loop order. Our methods yield remarkably accurate extrapolations from weak-field to strong-field, and from magnetic to electric background field, at both one-loop and two-loop order, based on surprisingly little perturbative input.

    ↳ hep-thhep-phmath-phmath.MPPRD(2021)·29 citations
26. 26*

    Determining the temperature in heavy-ion collisions with multiplicity distribution

    Y. D. Song🇨🇳 · R. Wang🇨🇳 · Y. G. Ma🇨🇳 · X. G. Deng🇨🇳 · H. L. Liu🇨🇳

    By relating the charge multiplicity distribution and the temperature of a de-exciting nucleus through a deep neural network, we propose that the charge multiplicity distribution can be used as a thermometer of heavy-ion collisions. Based on an isospin-dependent quantum molecular dynamics model, we study the caloric curve of reaction ${}^{103}$Pd + ${}^9$Be with the apparent temperature determined through the charge multiplicity distribution. The caloric curve shows a characteristic signature of nuclear liquid-gas phase transition around the apparent temperature $T_{\mathrm{ap}}$ $=$ $6.4\mathrm{MeV}$, which is consistent with that through a traditional heavy-ion collision thermometer, and indicates the viability of determining the temperature in heavy-ion collisions with multiplicity distribution.

    ↳ nucl-thhep-phnucl-exPLB(2021)·33 citations
27. 27*

    Relieving the $H_0$ tension with a new interacting dark energy model

    Li-Yang Gao🇨🇳 · Ze-Wei Zhao🇨🇳 · She-Sheng Xue🇮🇹 · Xin Zhang🇨🇳

    We investigate an extended cosmological model motivated by the asymptotic safety of gravitational field theory, in which the matter and radiation densities and the cosmological constant receive a correction parametrized by the parameters ${\delta }_G$ and ${\delta }_{\Lambda }$, leading to that both the evolutions of the matter and radiation densities and the cosmological constant slightly deviate from the standard forms. Here we explain this model as a scenario of vacuum energy interacting with matter and radiation. We consider two cases of the model: {(i) $\tilde{\Lambda }$CDM with one additional free parameter ${\delta }_G$, with ${\delta }_{\mathrm{G}}$ and ${\delta }_{\Lambda }$ related by a low-redshift limit relation and (ii) e$\tilde{\Lambda }$CDM with two additional free parameters ${\delta }_G$ and ${\delta }_{\Lambda }$ that are independent of each other.} We use two data combinations, CMB+BAO+SN (CBS) and CMB+BAO+SN+$H_0$ (CBSH), to constrain the models. We find that, in the case of using the CBS data, neither $\tilde{\Lambda }$CDM nor e$\tilde{\Lambda }$CDM can effectively alleviate the $H_0$ tension. However, it is found that using the CBSH data the $H_0$ tension can be greatly relieved by the models. In particular, in the case of e$\tilde{\Lambda }$CDM, the $H_0$ tension can be resolved to 0.71$\sigma$. We conclude that as an interacting dark energy model, $\tilde{\Lambda }$CDM is much better than $\Lambda (t)$CDM in the sense of both relieving the $H_0$ tension and fitting to the current observational data.

    ↳ astro-ph.COgr-qchep-phJCAP(2021)·117 citations
28. 28*

    Using associated top quark production to probe for new physics within the framework of effective field theory

    Brent R. Yates🇺🇸

    Signs of new physics are probed in the context of an Effective Field Theory using events containing one or more top quarks in association with additional leptons. Data consisting of proton-proton collisions at a center-of-mass energy of $\sqrt{s}=$13 TeV was collected at the LHC by the CMS experiment in 2017. We apply a novel technique to parameterize 16 dimension-six EFT operators in terms of the respective Wilson coefficients (WCs). A simultaneous fit is performed to the data in order to extract the two standard deviation confidence intervals (CIs) of the 16 WCs. The Standard Model value of zero is completely contained in most CIs, and is not excluded by a statistically significant amount in any interval.

    ↳ hep-exhep-ph2 citations
29. 29*

    Soft pions and transport near the chiral critical point

    Eduardo Grossi🇺🇸 · Alexander Soloviev🇺🇸 · Derek Teaney🇺🇸 · Fanglida Yan🇺🇸

    During the expansion of a heavy ion collision, the system passes close to the $O(4)$ critical point of QCD, and thus the fluctuations of the order parameter $(\sigma ,\vec{\pi })$ are expected to be enhanced. Our goal is to compute how these enhanced fluctuations modify the transport coefficients of QCD near the pseudo-critical point. We also make a phenomenological estimate for how chiral fluctuations could effect the momentum spectrum of soft pions. We first formulate the appropriate stochastic hydrodynamic equations close to the $O(4)$ critical point. Then, working in mean field, we determine the correlation functions of the stress tensor and the currents which result from this stochastic real time theory, and use these correlation functions to determine the scaling behavior of the transport coefficients. The hydrodynamic theory also describes the propagation of pion waves, fixing the scaling behavior of the dispersion curve of soft pions. We present scaling functions for the shear viscosity and the charge conductivities near the pseudo-critical point, and estimate the absolute magnitude of the critical fluctuations to these parameters and the bulk viscosity. Using the calculated pion dispersion curve, we estimate the expected critical enhancement of soft pion yields, and this estimate provides a plausible explanation for the excess seen in experiment relative to ordinary hydrodynamic computations. Our results motivate further phenomenological and numerical work on the implications of chiral symmetry on real time properties of thermal QCD near the pseudo-critical point.

    ↳ nucl-thhep-phPRD(2021)·63 citations
30. 30*

    The Highest Energy HAWC Sources are Likely Leptonic and Powered by Pulsars

    Takahiro Sudoh🇯🇵 · Tim Linden🇸🇪 · Dan Hooper🇺🇸

    The HAWC Collaboration has observed gamma rays at energies above 56 TeV from a collection of nine sources. It has been suggested that this emission could be hadronic in nature, requiring that these systems accelerate cosmic-ray protons or nuclei up to PeV-scale energies. In this paper, we instead show that the spectra of these objects favor a leptonic (inverse Compton) origin for their emission. More specifically, the gamma-ray emission from these objects can be straightforwardly accommodated within a model in which $\sim \mathcal{O}(10\%)$ of the host pulsar's spindown power is transferred into the acceleration of electrons and positrons with a power-law spectrum that extends to several hundred TeV or higher. The spectral break that is observed among these sources is naturally explained within the context of this simple model, and occurs at the energy where the timescale for energy losses matches the age of the pulsar. In contrast, this spectral feature cannot be straightforwardly accommodated in hadronic scenarios. Furthermore, hadronic models predict that these sources should produce more emission at GeV-scale energies than is observed. In light of these considerations, we conclude that HAWC's highest energy sources should be interpreted as TeV halos or pulsar wind nebulae, which produce their emission through inverse Compton scattering, and are powered by the rotational kinetic energy of their host pulsar.

    ↳ astro-ph.HEastro-ph.GAhep-phJCAP(2021)·42 citations
31. 31*

    Multimessenger constraints on the dark matter interpretation of the Fermi-LAT Galactic center excess

    Mattia Di Mauro🇮🇹 · Martin Wolfgang Winkler🇸🇪

    An excess of $\gamma$ rays in the data measured by the Fermi Large Area Telescope in the direction of the Galactic center has been reported in several publications. This excess, labeled as the Galactic center excess (GCE), is detected analyzing the data with different interstellar emission models, point source catalogs and analysis techniques. The characteristics of the GCE, recently measured with unprecedented precision, are all compatible with dark matter particles (DM) annihilating in the main halo of our Galaxy, even if other interpretations are still not excluded. We investigate the DM candidates that fit the observed GCE spectrum and spatial morphology. We assume a simple scenario with DM annihilating into a single channel but we inspect also more complicated models with two and three channels. We perform a search for a $\gamma$-ray flux from a list of 48 Milky Way dwarf spheroidal galaxies (dSphs) using state-of-the-art estimation of the DM density in these objects. Since we do not find any significant signal from the dSphs, we put upper limits on the annihilation cross section that result to be compatible with the DM candidate that fits the GCE. However, we find that the GCE DM signal is excluded by the AMS-02 $\bar{p}$ flux data for all hadronic and semi-hadronic annihilation channels unless the vertical size of the diffusion halo is smaller than 2 kpc -- which is in tension with radioactive cosmic ray fluxes and radio data. Furthermore, AMS-02 $e^{+}$ data rule out pure or mixed channels with a component of $e^{+}{e}^{-}$. The only DM candidate that fits the GCE spectrum and is compatible with constraints obtained with the combined dSphs analysis and the AMS-02 $\bar{p}$ and $e^{+}$ data annihilates purely into ${\mu }^{+}{\mu }^{-}$, has a mass of 60 GeV and roughly a thermal cross section.

    ↳ astro-ph.HEhep-phPRD(2021)·96 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.