We develop a novel way to probe subgalactic-scale matter distribution with diffractive lensing on gravitational waves. Five-year observations from Einstein Telescope and DECIGO are expected to probe $\textit{k}$ = 10 ∼ 10 Mpc down to $\textit{P}$ ($\textit{k}$) = 10 ∼ 10 Mpc level. These results can be interpreted in terms of primordial black holes in the range $\textit{M}$ ≳ 10 $\textit{M}$ down to $\textit{f}$ = 10 level, or QCD axion minihalos in the range $\textit{m}$ = 10 ∼ 10 eV. A key result of the paper is the approximate relation between the scale $\textit{k}$ and the gravitational wave frequency $\textit{f}$, derived in an ensemble of ‘multi-lensing’ events. This relation enables direct measurement of the power spectrum at specific scales, with sensitivities characterized by model-independent kernels $\textit{δP}$ ($\textit{k}$). Additionally, we delineate the statistical properties of ‘multi-lensing’ based on the ‘Fresnel number’ $\textit{N}$ . When $\textit{N}$ ≳ $$ \mathcal{O}(1) $$ , the statistical significance can be approximately calculated by Variance of lensing effects, which is directly related to the power spectrum among other moments of matter distribution.

South Korea

Sungjung Kim

Han Choi

Sunghoon Jung

Probing small-scale power spectrum with gravitational-wave diffractive lensing

Abstract The small cosmic microwave background (CMB) amplitude A$_{s}$ ≃ 10$^{−9}$ (or small temperature fluctuation δT/T ≃ 10$^{−5}$) typically requires an unnaturally small effective coupling of an inflaton λ$_{ϕ}$ ∼ 10$^{−14}$. In models with non-minimal coupling ξ, extra suppression of the amplitude, e.g. by the inflaton’s large field values, usually allows λ$_{ϕ}$ to be much larger, but at the price of ξ ≫ 1. Although the difficulties have not been strictly quantified, models with λ$_{ϕ}$ ≪ 1 or ξ ≫ 1 are harder to build. We show that the absence of new physics signals at TeV scale can suggest a relatively small  with , while constraining larger ξ with larger λ$_{ϕ}$ more strongly. Above all, this is possible by a connection between low- and high-energy physics that can be made in scenarios where the U(1)$_{X}$ Higgs is an inflaton at a high scale while its renormalization running also induces the Coleman–Weinberg mechanism for the electroweak symmetry breaking at a low scale. The best TeV-scale signals are Z$^{′}$ resonances and Higgs signal strengths. We further find the connection particularly useful since the Z$^{′}$ mass is upper bounded in order to produce the correct A$_{s}$ and the weak scale simultaenously. Utilizing the intriguing upper bounds, we work out the prospects for LHC 13 and 100 TeV pp colliders probing the parameter space of the small CMB amplitude in such a model.

Kiyoharu Kawana

Low-energy probes of the small cosmic microwave background amplitude in models of the radiative Higgs mechanism

We study the tagging of Higgs exotic decay signals using different types of deep neural networks (DNNs) while focusing on the <math><mrow><msup><mrow><mi>W</mi></mrow><mrow><mo>±</mo></mrow></msup><mi>h</mi></mrow></math> associated production channel followed by Higgs decaying into <math><mi>n</mi></math> <math><mi>b</mi></math> quarks with <math><mi>n</mi><mo>=</mo><mn>4</mn></math>, 6, and 8. All the Higgs decay products are collected into a fat jet, to which we apply further selection using the DNNs. Three kinds of DNNs are considered—namely, the convolutional neural network, the recursive neural network, and the particle flow network (PFN). The PFN can achieve the best performance because its structure allows one to enfold more information in addition to the four-momenta of the jet constituents, such as the particle identifier, and tracks the parameters. Using the PFN as an example, we verify that it can serve as an efficient tagger even though it is trained on a different event topology with different <math><mi>b</mi></math> multiplicity from the actual signal. The projected sensitivity to the branching ratio of Higgs decaying into <math><mi>n</mi></math> <math><mi>b</mi></math> quarks at the HL-LHC are 10%, 3%, and 1%, for <math><mi>n</mi><mo>=</mo><mn>4</mn></math>, 6, and 8, respectively.

United States

Zhen Liu

Lian-Tao Wang

Ke-Pan Xie

Probing Higgs boson exotic decays at the LHC with machine learning

This paper presents a combined analysis of the potential of a future electron-positron collider to constrain the Higgs, top, and electroweak sectors of the Standard Model effective field theory. The leading contributions of operators involving top quarks arise mostly at one-loop suppressed order and can be captured by the renormalization group mixing with Higgs operators. We perform global fits with an extended basis of 29 parameters, including both Higgs and top operators, to the projections for the Higgs, top, and electroweak precision measurements at the International Linear Collider (ILC). The determination of the Higgs boson couplings in the 250 GeV stage of the ILC is initially severely degraded by the additional top-quark degrees of freedom, but can be nearly completely recovered by the inclusion of precise measurements of top-quark EW couplings at the LHC. The physical Higgs couplings are relatively robust, as the top mass is larger than the energy scale of electroweak processes. The effect of the top operators on the bounds on the Wilson coefficients is much more pronounced and may limit our ability to identify the source of deviations from the Standard Model. Robust global bounds on all Wilson coefficients are only obtained when the 500 GeV stage of the ILC is included.

Junghwan Lee

Spain

Martin Perelló

Japan

Junping Tian

Marcel Vos

Higgs, top quark, and electroweak precision measurements at future <math><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> colliders: A combined effective field theory analysis with renormalization mixing

We propose a novel dark matter (DM) scenario based on a first-order phase transition in the early Universe. If dark fermions acquire a huge mass gap between true and false vacua, they can barely penetrate into the new phase. Instead, they get trapped in the old phase and accumulate to form macroscopic objects, dubbed Fermi-balls. We show that Fermi-balls can explain the DM abundance in a wide range of models and parameter space, depending most crucially on the dark-fermion asymmetry and the phase transition energy scale (possible up to the Planck scale). They are stable by the balance between fermion’s quantum pressure against free energy release, hence turn out to be macroscopic in mass and size. However, this scenario generally produces no detectable signals (which may explain the null results of DM searches), except for detectable gravitational waves for electroweak scale phase transitions; although the detection of such stochastic gravitational waves does not necessarily imply a Fermi-ball DM scenario.

Jeong-Pyong Hong

Fermi-ball dark matter from a first-order phase transition

The axion-gravity Chern-Simons coupling is well motivated but is relatively weakly constrained, partly due to difficult measurements of gravity. We study the sensitivity of LIGO measurements of chirping gravitational waves (GWs) on such coupling. When the frequency of the propagating GW matches with that of the coherent oscillation of axion dark matter field, the decay of axions into gravitons can be stimulated, resonantly enhancing the GW. Such a resonance peak can be detected at LIGO as a deviation from the chirping waveform. Since all observed GWs will undergo similar resonant enhancement from the Milky Way (MW) axion halo, LIGO <math><mrow><mi>O</mi><mn>1</mn><mo>+</mo><mi>O</mi><mn>2</mn></mrow></math> observations can potentially provide the strongest constraint on the coupling, at least for the axion mass <math><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>a</mi></mrow></msub><mo>=</mo><mn>5</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>13</mn></mrow></msup><mo>−</mo><mn>5</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>12</mn></mrow></msup><mtext> </mtext><mtext> </mtext><mi>eV</mi></mrow></math>. Along the course, we also emphasize the relevance of the finite coherence of axion fields and the ansatz separating forward and backward propagations of GWs. As a result, the parity violation of the Chern-Simons coupling is not observable from chirping GWs.

TaeHun Kim

Jiro Soda

Germany

Yuko Urakawa

Constraining the gravitational coupling of axion dark matter at LIGO

A resonance peak in the invariant mass spectrum has been the main feature of a particle at collider experiments. However, broad resonances not exhibiting such a sharp peak are generically predicted in new physics models beyond the Standard Model. Without a peak, how do we discover a broad resonance at colliders? We use machine learning technique to explore answers beyond common knowledge. We learn that, by applying deep neural network to the case of a $$t\bar{t}$$ <math><mrow><mi>t</mi><mover><mrow><mi>t</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></math>  resonance, the invariant mass $$M_{t\bar{t}}$$ <math><msub><mi>M</mi><mrow><mi>t</mi><mover><mrow><mi>t</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></msub></math>  is still useful, but additional information from off-resonance region, angular correlations, $$p_T$$ <math><msub><mi>p</mi><mi>T</mi></msub></math> , and top jet mass are also significantly important. As a result, the improved LHC sensitivities do not depend strongly on the width. The results may also imply that the additional information can be used to improve narrow-resonance searches too. Further, we also detail how we assess machine-learned information.

Dongsub Lee

Beyond $$M_{t\bar{t}}$$ <math><msub><mi>M</mi><mrow><mi>t</mi><mover><mrow><mi>t</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></msub></math> : learning to search for a broad $$t\bar{t}$$ <math><mrow><mi>t</mi><mover><mrow><mi>t</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></math>  resonance at the LHC

A light scalar dark matter (DM) is allowed in a wide range of its mass and interaction types. We show that the light scalar DM may be probed in a new way from final years of neutron-star (NS) binary inspirals. If the DM interacts with the neutron, its long wave coherence in the background can induce the time-oscillating mass shift, to which the binary inspiral is inherently sensitive, but the sensitivity is found to be significantly enhanced by a large number of gravitational-wave (GW) cycles during year-long highest-frequency measurements in the broadband <math><mi>f</mi><mo>≃</mo><mn>0.01</mn><mi>–</mi><mn>1000</mn><mtext> </mtext><mtext> </mtext><mi>Hz</mi></math>. Such broadband measurements that can be realized by a future detector network including LIGO and mid-band detectors can probe unconstrained parameter space of the light scalar DM.

Han Gil Choi

New probe of dark matter-induced fifth force with neutron star inspirals

Future <math><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> colliders give the promise of model-independent determinations of the couplings of the Higgs boson. In this paper, we present an improved formalism for extracting Higgs boson couplings from <math><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> data, based on the effective field theory description of corrections to the Standard Model. We apply this formalism to give projections of Higgs coupling accuracies for stages of the International Linear Collider and for other proposed <math><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> colliders.

Tim Barklow

Keisuke Fujii

Robert Karl

Jenny List

Tomohisa Ogawa

Michael E. Peskin

Improved formalism for precision Higgs coupling fits

The observation of Higgs pair production at high-energy colliders can give evidence for the presence of a triple Higgs coupling. However, the actual determination of the value of this coupling is more difficult. In the context of general models for new physics, double Higgs production processes can receive contributions from many possible beyond-Standard-Model effects. This dependence must be understood if one is to make a definite statement about the deviation of the Higgs field potential from the Standard Model. In this paper, we study the extraction of the triple Higgs coupling from the process <math><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo>→</mo><mi>Z</mi><mi>h</mi><mi>h</mi></math>. We show that, by combining the measurement of this process with other measurements available at a 500 GeV <math><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> collider, it is possible to quote model-independent limits on the effective field theory parameter <math><msub><mi>c</mi><mn>6</mn></msub></math> that parametrizes modifications of the Higgs potential. We present precise error estimates based on the anticipated International Linear Collider physics program, studied with full simulation. Our analysis also gives new insight into the model-independent extraction of the Higgs boson coupling constants and total width from <math><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> data.

Model-independent determination of the triple Higgs coupling at <math><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> colliders