We study the new $Z'$ boson as a portal for the production of Higgs bosons $h_0$ and $H_0$ predicted by the Bestest Little Higgs Model through Higgs-strahlung processes $\mu^+\mu^- \to (Z, Z') \to Zh_0, ZH_0$ . We focus on the resonant and nonresonant effects of the $Zh_0, ZH_0$ signals. In our analysis, we consider the center-of-mass energies of $\sqrt{s}=3, 4, 6, 10, 30$ TeV and integrated luminosities of ${\cal{L}}=2, 4, 6, 10, 30$ ${ {\rm{ab}}^{-1}}$ projected for a future muon collider. The possibility of performing precision measurements for Higgs bosons $h_0$ and $H_0$ is very promising for the future muon collider. Furthermore, our results may be useful to the High Energy Physics community. Complementarily, we generate and provide the Feynman rules necessary for studying processes $\mu^+\mu^- \to (Z, Z') \to Zh_0, ZH_0$ .

J.M. Martínez-Martínez

A. Gutiérrez-Rodríguez

E. Cruz-Albaro

M.A. Hernández-Ruíz

New $\textit{Z}$' boson of the bestest little Higgs model as a portal to signatures of Higgs bosons $\textit{h}$ $_{0}$ and $\textit{H}$ $_{0}$ at the future muon collider

Using <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ψ</mi><mo stretchy="false">(</mo><mn>3686</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><msub><mrow><mi>h</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math> decays from a data sample of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>27.12</mn><mo>±</mo><mn>0.14</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>8</mn></mrow></msup><mtext> </mtext><mtext> </mtext><mi>ψ</mi><mo stretchy="false">(</mo><mn>3686</mn><mo stretchy="false">)</mo></mrow></math> events collected by the BESIII detector at the BEPCII collider, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mi>c</mi></msub></math> radiative decays to multiple light hadrons below <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2.8</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></math>—<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><mi>η</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi><mn>2</mn><mo stretchy="false">(</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><mo stretchy="false">)</mo></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi><mi>p</mi><mover accent="true"><mi>p</mi><mo stretchy="false">¯</mo></mover></math>—are observed for the first time, each with a significance greater than <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>5</mn><mi>σ</mi></math>. The corresponding branching fractions are measured. Furthermore, intermediate states are investigated, leading to the first observation of the decay process of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>h</mi></mrow><mrow><mi>c</mi></mrow></msub><mo stretchy="false">→</mo><mi>γ</mi><msub><mrow><mi>f</mi></mrow><mrow><mn>2</mn></mrow></msub><mo stretchy="false">(</mo><mn>1270</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>γ</mi><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> with a significance of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>5.1</mn><mi>σ</mi></math>. This observation represents the first instance of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mi>c</mi></msub></math> radiative decay to a tensor state.

China

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

X.C. Ai

Germany

R. Aliberti

Italy

A. Amoroso

Q. An

Y. Bai

JINR

O. Bakina

Y. Ban

H.R. Bao

Poland

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M. Bertani

D. Bettoni

F. Bianchi

E. Bianco

A. Bortone

I. Boyko

United States

R.A. Briere

A. Brueggemann

H. Cai

M.H. Cai

X. Cai

A. Calcaterra

G.F. Cao

N. Cao

Türkiye

S.A. Cetin

X.Y. Chai

J.F. Chang

G.R. Che

Y.Z. Che

G. Chelkov

C. Chen

C.H. Chen

Chao Chen

G. Chen

H.S. Chen

H.Y. Chen

M.L. Chen

S.J. Chen

S.L. Chen

S.M. Chen

T. Chen

X.R. Chen

X.T. Chen

Y.B. Chen

Y.Q. Chen

Z.J. Chen

South Korea

S.K. Choi

X. Chu

G. Cibinetto

F. Cossio

J.J. Cui

H.L. Dai

J.P. Dai

A. Dbeyssi

R.E. de Boer

D. Dedovich

C.Q. Deng

Z.Y. Deng

A. Denig

I. Denysenko

M. Destefanis

F. De Mori

B. Ding

X.X. Ding

Y. Ding

Y.X. Ding

J. Dong

L.Y. Dong

M.Y. Dong

X. Dong

M.C. Du

S.X. Du

Y.Y. Duan

Z.H. Duan

P. Egorov

G.F. Fan

J.J. Fan

Y.H. Fan

J. Fang

S.S. Fang

W.X. Fang

Y.Q. Fang

R. Farinelli

L. Fava

F. Feldbauer

G. Felici

C.Q. Feng

J.H. Feng

Y.T. Feng

M. Fritsch

C.D. Fu

J.L. Fu

Y.W. Fu

Observation of Charmonium <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>h</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math> Radiative Decays to Multiple Light Hadrons and the Tensor State <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>f</mi></mrow><mrow><mn>2</mn></mrow></msub><mo stretchy="false">(</mo><mn>1270</mn><mo stretchy="false">)</mo></mrow></math>

We study the dynamics of domain walls formed through the spontaneous breaking of an approximate <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="double-struck">Z</mi><mn>2</mn></msub></math> symmetry in a scalar field, focusing on their collapse under the influence of quantum and thermal corrections induced by a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="double-struck">Z</mi><mn>2</mn></msub></math>-violating Yukawa coupling to Dirac fermions in the thermal bath. The thermal effects make the potential bias between the true and false vacua dependent on the temperature and may lead to notable variations in the annihilation temperature of domain walls, in addition to the shift caused by temperature-independent quantum corrections. These modifications could substantially alter the gravitational wave spectrum produced by collapsing domain walls, potentially providing observable signatures for future gravitational wave detection experiments.

Qing-Quan Zeng

Xi He

Zhao-Huan Yu

Jiaming Zheng

Collapsing domain walls with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="double-struck">Z</mi><mn>2</mn></msub></math>-violating coupling to thermalized fermions and their impact on gravitational wave detections

We show that <math altimg='si1.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>Q</mi><mo stretchy='false'>)</mo></math> cosmology with a non-trivial connection, namely the Connection II of the literature, is dynamically equivalent with a quintom-like model. In particular, we show that the scalar field arising from the non-linear <math altimg='si1.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>Q</mi><mo stretchy='false'>)</mo></math> form, and the scalar field associated to the non-trivial connection, are combined to provide one canonical and one phantom field in the minisuperspace Lagrangian. Hence, the combination of two well-behaved fields appears effectively as a phantom field. This is fundamentally different from the usual approach in phantom and quintom cosmology, in which the phantom field is introduced ad hoc, and thus it may open a new way to handle the phantom fields, namely as effective realizations of the connection-related canonical fields.

Greece

Cyprus

Spyros Basilakos

Chile

South Africa

Andronikos Paliathanasis

Emmanuel N. Saridakis

Equivalence of <italic>f</italic>( <italic>Q</italic>) cosmology with quintom-like scenario: The phantom field as effective realization of the non-trivial connection

Within the nonrelativistic QCD framework, we calculate the double heavy quarkonium (double charmonium and double bottomonium) production at a future super <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> factory and at the Circular Electron Positron Collider (CEPC) and Electron-Positron Future Circular Collider (FCC-ee). The complete color-octet (CO) channels in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>γ</mi><mo>*</mo></msup><mo>/</mo><msup><mi>Z</mi><mo>*</mo></msup></math>-propagated process are considered along with the color-singlet (CS) channels at leading order of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi>s</mi></msub></math>. We found that the contributions of CO states to the total cross section are significant or dominant for many processes within the energy region at a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> factory and at the CEPC and FCC-ee. The experimental measurements will help us to verify the CO mechanism. Among these CO channels, the gluon fragmentation process (into <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mmultiscripts><mrow><mi>S</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>3</mn></mrow></mmultiscripts></mrow><mrow><mn>1</mn></mrow><mrow><mn>8</mn></mrow></msubsup></mrow></math> states at leading order) is most important. The comparison between the theoretical results and future data may give constraints to the CO matrix elements. Additionally, we consider the relativistic corrections to both the CS and CO channels which decrease the cross sections significantly. Specially, the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi></math> factors are about 0.5 for most charmonium channels. We get estimates of the events for double heavy quarkonium production. The final events of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>+</mo><msub><mi>η</mi><mi>c</mi></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>+</mo><mi>J</mi><mo>/</mo><mi>ψ</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>η</mi><mi>c</mi></msub><mo>+</mo><msub><mi>η</mi><mi>c</mi></msub></math> production, with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> reconstructed by lepton pair and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>η</mi><mi>c</mi></msub></math> reconstructed by hadronic decays, would be (1, 8, 4) and (11, 77, 37) at the CEPC (2-yr) and at the FCC-ee (4-yr) for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> factory mode, respectively.

Xiao-Peng Wang

Guang-Zhi Xu

Kui-Yong Liu

Double heavy quarkonia production with color-octet channels at a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> factory and at the CEPC and FCC-ee

We study the discovery potential of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> branching ratios due to contributions induced by the minimal supersymmetric standard model (MSSM) electroweak sector, assuming that the squarks and gluinos are heavy. Precision measurements at a future <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> factory would yield sensitivity to MSSM that is complementary to direct searches at the LHC, provided that the systematic uncertainties can be reduced to a level comparable to the expected statistical uncertainties.

Simon Knapen

Kevin Langhoff

Zoltan Ligeti

Imprints of supersymmetry at a future <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>Z</mi></mrow></math> factory

We explore the prospects for probing new physics (NP) beyond the Standard Model (SM) at the future lepton colliders through precision measurements of $\textit{e}$ $\textit{e}$ → $$ f\overline{f} $$ observables off the $\textit{Z}$ resonance. We consider the interference between the SM contributions and those arising from the dimension-6 four-fermion effective operators that encode the effects of NP, yielding a linear dependence on the latter. This linear dependence in general increases with the collision energy offset from the $\textit{Z}$ pole. We consider a variety of asymmetries in order to enhance the NP sensitivity while reducing the experimental systematic and theoretical SM uncertainties: the inclusive above- and below-$\textit{Z}$-resonance cross section asymmetry ($\textit{A}$ ) as well as the conventional forward-backward ($\textit{A}$ ) and polarization ($\textit{A}$ ) asymmetries. Based on the projected statistical uncertainties at the Circular Electron-Positron Collider (CEPC), we find that the measurement of $\textit{A}$ could extend the sensitivity to the NP mass scale by as much as a factor of ~ 7 compared to the present reach obtained with the CERN Large Electron Positron Collider. The projected systematic theoretical SM uncertainties substantially reduce this sensitivity gain. For $\textit{A}$ , the experimental systematic uncertainties has a marginal impact on the gain in NP reach, whereas the SM theoretical uncertainties remain a significant barrier to realizing the full NP sensitivity. Analogous conclusions apply to the CERN Future Circular Collider (FCC-ee) and International Linear Collider (ILC).

Shao-Feng Ge

Zhuoni Qian

Michael Ramsey-Musolf

Jia Zhou

New physics off the $\textit{Z}$-pole: $\textit{e}$

Motivated by a small but intriguing excess observed in the decay mode $\textit{H}$ → $\textit{ℓ}$ $\textit{ℓ}$ $\textit{γ}$ reported by both the ATLAS and CMS collaborations, we explore the possibility that new physics contributes directly to the effective $$ H\overline{\mathcal{ll}}\gamma $$ coupling rather than modifying the $\textit{Z}$ peak. Concretely, we consider a dimension-8 operator that could arise from new particles via box diagrams. Such non-resonant contribution may provide an alternative origin for current or future excesses. We examine how experimental cuts may distinguish between possible modifications of the $\textit{Z}$ peak and non-resonant contributions. The currently measured excess requires that the new physics scale is relatively low (Λ ~ $\textit{v}$). However, we show that it may remain within current experimental bounds. In particular, we illustrate this using a simplified model, motivated by the dark matter problem, and discuss its other experimental constraints.

Belgium

Aliaksei Kachanovich

Jean Kimus

Steven Lowette

Michel Tytgat

On new physics off the Z peak in $\textit{H → ℓ}$

The current projected sensitivity on the electromagnetic coupling <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>α</mi></mrow><mrow><mi>em</mi></mrow></msub><mo stretchy="false">(</mo><msubsup><mrow><mi>m</mi></mrow><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msubsup><mo stretchy="false">)</mo></mrow></math> represents a bottleneck for the precision electroweak program at FCC-ee. We propose a novel methodology to extract this coupling directly from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math>-pole data. By comparing the differential distribution of electrons, muons, and positrons in the forward region, the approach achieves a projected statistical sensitivity below the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mn>10</mn><mrow><mo>−</mo><mn>5</mn></mrow></msup></math> level, representing a significant improvement over other methods. We assess the impact of leading parametric uncertainties including that of the top quark mass.

CERN

Marc Riembau

Precise Extraction of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>α</mi></mrow><mrow><mi>em</mi></mrow></msub><mo stretchy="false">(</mo><msubsup><mrow><mi>m</mi></mrow><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msubsup><mo stretchy="false">)</mo></mrow></math> at the Tera-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> Stage of a Future Circular Collider

We propose a novel method to determine the strong coupling of quantum chromodynamics (QCD) and fix its running behavior at all scales by using the Bjorken sum rules (BSR). The BSR defines an effective coupling <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi>α</mi></mrow><mrow><mi>s</mi></mrow><mrow><msub><mrow><mi>g</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow></msubsup><mo stretchy="false">(</mo><mi>Q</mi><mo stretchy="false">)</mo></mrow></math> which includes the nonperturbative higher-twist corrections and perturbative QCD (pQCD) corrections to the leading-twist part. For the leading-twist part of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>α</mi><mi>s</mi><msub><mi>g</mi><mn>1</mn></msub></msubsup><mo stretchy="false">(</mo><mi>Q</mi><mo stretchy="false">)</mo></math>, we adopt the infinite-order scale-setting procedure of the principle of maximum conformality (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>PMC</mi><mi>∞</mi></msub></math>) to deal with its pQCD corrections, which reveals the intrinsic conformality of the series and eliminates conventional renormalization scheme-and-scale ambiguities. Using the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>PMC</mi><mi>∞</mi></msub></math> approach, we not only eliminate the first kind of residual scale dependence due to uncalculated higher-order terms, but also resolve the previous “self-consistency problem.” The light-front holographic QCD model is used for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>α</mi><mi>s</mi><msub><mi>g</mi><mn>1</mn></msub></msubsup><mo stretchy="false">(</mo><mi>Q</mi><mo stretchy="false">)</mo></math> in the infrared region, which also reveals a conformal behavior at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi><mo stretchy="false">→</mo><mn>0</mn></math>. As a combination, we obtain a precise <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>α</mi><mi>s</mi><msub><mi>g</mi><mn>1</mn></msub></msubsup><mo stretchy="false">(</mo><mi>Q</mi><mo stretchy="false">)</mo></math> at all scales, which matches well with the known experimental data with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>p</mi></math>-value <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>∼</mo><mn>98</mn><mo>%</mo></math>, and determines the strong coupling constant at the scale <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>M</mi><mi>Z</mi></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi>s</mi></msub><mo stretchy="false">(</mo><msub><mi>M</mi><mi>Z</mi></msub><mo stretchy="false">)</mo><mo>=</mo><mn>0.122</mn><msubsup><mn>0</mn><mrow><mo>−</mo><mn>0.0012</mn></mrow><mrow><mo>+</mo><mn>0.0011</mn></mrow></msubsup><mo stretchy="false">(</mo><mi mathvariant="normal">Δ</mi><mi>κ</mi><msubsup><mo stretchy="false">)</mo><mrow><mo>+</mo><mn>0.0007</mn></mrow><mrow><mo>−</mo><mn>0.0046</mn></mrow></msubsup><mo stretchy="false">(</mo><mrow><mi>the</mi><mo>.</mo></mrow><mo stretchy="false">)</mo></math>, where the first error comes from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi><mi>κ</mi></math> of LFHQCD model and the second error is from the second kind of residual scale dependence.

Qing Yu

Xing-Gang Wu

Hua Zhou

Jian-Ming Shen

Determination of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi>s</mi></msub><mo stretchy="false">(</mo><msub><mi>M</mi><mi>Z</mi></msub><mo stretchy="false">)</mo></math> via a high-precision effective coupling <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>α</mi><mi>s</mi><msub><mi>g</mi><mn>1</mn></msub></msubsup><mo stretchy="false">(</mo><mi>Q</mi><mo stretchy="false">)</mo></math>