A search for flavor-changing neutral current interactions of the top quark (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>t</mi></mrow></math>) and the Higgs boson (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi></math>) is presented. The search is based on proton-proton collision data collected in 2016–2018 at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, and corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>138</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>. Events containing a pair of leptons with the same-sign electric charge and at least one jet are considered. The results are used to constrain the branching fraction (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi></math>) of the top quark decaying to a Higgs boson and an up (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>u</mi></math>) or charm (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>c</mi></math>) quark. No significant excess above the estimated background was found. The observed (expected) upper limits at a 95% confidence level are found to be 0.072% (0.059%) for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>t</mi><mo stretchy="false">→</mo><mi>H</mi><mi>u</mi><mo stretchy="false">)</mo></mrow></math> and 0.043% (0.062%) for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>t</mi><mo stretchy="false">→</mo><mi>H</mi><mi>c</mi><mo stretchy="false">)</mo></math>. These results are combined with two other searches performed by the CMS Collaboration for flavor-changing neutral current interactions of top quarks and Higgs bosons in final states where the Higgs boson decays to either a pair of photons or a pair of bottom quarks. The resulting observed (expected) upper limits at the 95% confidence level are 0.019% (0.027%) for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>t</mi><mo stretchy="false">→</mo><mi>H</mi><mi>u</mi><mo stretchy="false">)</mo></math> and 0.037% (0.035%) for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>t</mi><mo stretchy="false">→</mo><mi>H</mi><mi>c</mi><mo stretchy="false">)</mo></math>.

Armenia

A. Hayrapetyan

A. Tumasyan

Austria

W. Adam

J.W. Andrejkovic

T. Bergauer

S. Chatterjee

K. Damanakis

M. Dragicevic

P.S. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

I. Mikulec

J. Schieck

R. Schöfbeck

D. Schwarz

M. Sonawane

S. Templ

W. Waltenberger

C.E. Wulz

Belgium

M.R. Darwish

T. Janssen

P. Van Mechelen

E.S. Bols

J. D’Hondt

S. Dansana

A. De Moor

M. Delcourt

S. Lowette

I. Makarenko

D. Müller

S. Tavernier

M. Tytgat

G.P. Van Onsem

S. Van Putte

D. Vannerom

B. Clerbaux

A.K. Das

G. De Lentdecker

H. Evard

L. Favart

P. Gianneios

D. Hohov

J. Jaramillo

A. Khalilzadeh

F.A. Khan

K. Lee

M. Mahdavikhorrami

A. Malara

S. Paredes

L. Thomas

M. Vanden Bemden

C. Vander Velde

P. Vanlaer

M. De Coen

D. Dobur

Y. Hong

J. Knolle

L. Lambrecht

G. Mestdach

K. Mota Amarilo

C. Rendón

A. Samalan

K. Skovpen

N. Van Den Bossche

J. van der Linden

L. Wezenbeek

A. Benecke

A. Bethani

G. Bruno

C. Caputo

C. Delaere

I.S. Donertas

A. Giammanco

Sa. Jain

V. Lemaitre

J. Lidrych

P. Mastrapasqua

T.T. Tran

S. Wertz

Brazil

G.A. Alves

E. Coelho

C. Hensel

T. Menezes De Oliveira

A. Moraes

P. Rebello Teles

M. Soeiro

W.L. Aldá Júnior

M. Alves Gallo Pereira

M. Barroso Ferreira Filho

H. Brandao Malbouisson

W. Carvalho

J. Chinellato

E.M. Da Costa

G.G. Da Silveira

D. De Jesus Damiao

S. Fonseca De Souza

R. Gomes De Souza

J. Martins

Search for flavor-changing neutral current interactions of the top quark mediated by a Higgs boson in proton-proton collisions at 13 TeV

We apply the variational Monte Carlo method based on neural network quantum states, using a neural autoregressive flow architecture as our ansatz, to determine the ground state wave function of the bosonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>SU</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></mrow></math> Yang-Mills-type two-matrix model at strong coupling. Previous literature hinted at the inaccuracy of such an approach at strong coupling. In this work, the accuracy of the results is tested using lattice Monte Carlo simulations: we benchmark the expectation value of the energy of the ground state for system sizes <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> that are beyond brute-force exact diagonalization methods. We observe that the variational method with neural network states reproduces the right ground state energy when the width of the network employed in this work is sufficiently large. We confirm that the correct result is obtained for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi><mo>=</mo><mn>2</mn></math> and 3, while obtaining a precise value for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi><mo>=</mo><mn>4</mn></math> requires more resources than the amount available for this work.

Germany

Norbert Bodendorfer

Türkiye

Onur Oktay

United Kingdom

Vaibhav Gautam

Masanori Hanada

Japan

Enrico Rinaldi

Variational Monte Carlo with neural network quantum states for a Yang-Mills matrix model

Studies of scattering processes in scalar models with two Higgs doublets have recently hinted at a connection between the absence of flavor-space entanglement in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi mathvariant="normal">Φ</mi><mo>+</mo></msup><msup><mi mathvariant="normal">Φ</mi><mn>0</mn></msup></math> scattering and an emergent SO(8) symmetry in the scalar potential. We extend the analysis to all scattering channels with two particles in the external states by treating the process as a four-qubit system in the weak isospin and flavor subspaces of the two-particle state. We work with a generic quantum-information-theoretic principle encoded by the commutativity of the initial-state density matrix with the transition matrix (at leading order in perturbation theory). This yields a special case of the entanglement minimization conditions previously derived in the literature, and we interpret the principle in terms of the conservation of nonstabilizerness (or “magic”). Working at leading order in the quartic couplings, we find a consistent set of conditions that implies an SO(8) symmetry on the quartic part of the potential for scattering an arbitrary initial state but a smaller <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>SU</mi><mo stretchy="false">(</mo><mn>2</mn><msub><mo stretchy="false">)</mo><mi>R</mi></msub></math> symmetry when the initial state is chosen to have definite isospin. This follows by accounting for Bose symmetry in the initial state, which introduces entanglement between the isospin and flavor subspaces.

Australia

Giorgio Busoni

John Gargalionis

Ewan N.V. Wallace

Martin J. White

Emergent symmetry in a two-Higgs-doublet model from quantum information and nonstabilizerness

China

Farzan Mushtaq

Xia Tiecheng

Faisal Javed

Azerbaijan

Pakistan

Allah Ditta

Saudi Arabia

Bander Almutairi

G. Mustafa

Uzbekistan

Abdullo Hakimov

Erratum: Impact of loop quantum gravity on gravitational lensing, thermal fluctuations, tidal force and geodesic deviation around a black hole

Mesons’ internal structure and dynamics may be accessed through hard exclusive electroproduction processes such as deeply virtual Compton scattering in both near forward and near backward kinematics. With the help of the Sullivan process, which allows us to use a nucleon target as a quasireal <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>π</mi></math> meson emitter, we study backward scattering in the framework of collinear QCD factorization where pion-to-photon transition distribution amplitudes describe the photon content of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>π</mi></math> meson. We present a model of these transition distribution amplitudes based on the overlap of light-front wave functions primarily developed for generalized parton distributions, using a previously computed pion light-front wave function and deriving a new model for the light-front wave functions of the photon. This leads us to an estimate of the cross sections for JLab energies. We conclude that deeply virtual <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>e</mi><mi>p</mi><mo stretchy="false">→</mo><mi>e</mi><mi>γ</mi><mi>M</mi><mi>n</mi></math> processes, in backward kinematics, may be experimentally discovered in the near future.

France

Abigail R. Castro

Cédric Mezrag

Spain

Jose M. Morgado Chávez

Bernard Pire

Backward DVCS in a Sullivan process

The process of all-vortex nonlinear Compton scattering in an intense and polarized laser field, in which the initial and final electrons and the emitted <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi></math> photon are all in vortex states, is studied theoretically. We develop a formalism for the process, which allows us to study the exchanges of the orbital angular momentum (OAM) and spin angular momentum among the electron, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi></math> photon, and laser. A wave packet of the Bessel-Gaussian type is adopted to describe the initial vortex electron for the purpose of normalization. Both circularly and linearly polarized lasers are examined. Substantial numerical calculations are performed to reveal the physics of the exchanges of the OAM and spin angular momentum. The strong impact of the laser intensity and the opening angle of the initial vortex electron is demonstrated. Our results also suggest possible scenarios for the separation of the emitted <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi></math> photons with different OAMs, as well as a possible way which could help to distinguish the OAM and spin of the vortex particle by the multipeak structure in the spectrum of the emitted photon.

Yi Liao

Quan-Yu Wang

Yuanbin Wu

All-vortex nonlinear Compton scattering in a polarized laser field

To better understand recent predictions on the moat regime of quantum chromodynamics (QCD) matter, this paper extends the previous work within the two-flavor quark-meson (QM) model to the more realistic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mo>+</mo><mn>1</mn></math> flavor Polyakov-quark-meson (PQM) model. Mainly, two effects are further taken into account: strange quark and confinement coded through Polyakov loop. Model parameters are chosen to consistently reproduce the pseudocritical temperature from lattice QCD, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi mathvariant="normal">C</mi></msub><mo>∼</mo><mn>156</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math>, and the baryon chemical potential at the critical end point (CEP) from functional renormalization group to QCD matter (FRG-QCD), <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>μ</mi></mrow><mrow><mi mathvariant="normal">B</mi></mrow></msub><mrow><mo stretchy="false">(</mo><mi>CEP</mi><mo stretchy="false">)</mo></mrow><mo>∼</mo><mn>635</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math>. It is found that the basic features of moat regimes for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>σ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>π</mi></math> mesons remain similar to those from QM model: Moat regimes cover the region where temperature or baryon chemical potential is large; reentrances occur around the critical baryon chemical potential of chiral transition at zero temperature. Thus, the FRG-QCD results can still not be well understood, especially why the extrapolated CEP should be consistent with the boundaries of moat regimes for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>σ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>π</mi></math> mesons. Nevertheless, some basic features can be understood qualitatively, and it is consistent that the pole energies are increasing functions of momenta in the whole <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi><mo>−</mo><msub><mi>μ</mi><mi mathvariant="normal">B</mi></msub></math> plane. The moat regime and pole energy of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi></math> mesons are also studied with the features similar.

Gaoqing Cao

Moat regimes within a (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2</mn><mo>+</mo><mn>1</mn></mrow></math>)-flavor Polyakov-quark-meson model

We use modern dimensionally-reduced effective field theory methods, with careful attention to scale hierarchies, to analyze and catalog the types of first-order electroweak phase transitions that are possible in the Standard Model Effective Field Theory (SMEFT). Our calculations lay the necessary groundwork to perform gauge invariant, properly resummed perturbative expansions, and therefore address many of the theoretical problems with phase transition calculations.

Sweden

Eliel Camargo-Molina

Rikard Enberg

Johan Löfgren

A catalog of first-order electroweak phase transitions in the Standard Model Effective Field Theory

In this paper, we present an innovative approach to resolving type IV singularities in fermionic quantum cosmology. The Eisenhart–Duval lift procedure is employed to construct an extended minisuperspace metric, which allows for the formulation of the Dirac equation in minisuperspace. Through this approach, fermionic degrees of freedom are effectively incorporated into a homogeneous and isotropic cosmological model with a scalar field. By applying a kind of the Born-Oppenheimer approximation, solutions to the Dirac equation for an approximate potential characteristic of type IV singularities are obtained, expressed in terms of Tricomi confluent hypergeometric functions and associated Laguerre polynomials. The elimination of non-physical, divergent solutions results in a quantum regularization of the classical singularity. These results indicate the potential of fermionic models in quantum cosmology for mitigating the singularity problem.

Poland

Paweł Kucharski

Adam Balcerzak

Fermionic quantum cosmology as a framework for resolving type IV singularities

In this paper, we investigate the effects of Lorentz violation on correlations harvesting, specifically focusing on the harvested entanglement and harvested mutual information between two Unruh-DeWitt detectors interacting with a quantum field in the Lorentz-violating BTZ-like black hole spacetime. Our findings reveal that Lorentz symmetry breaking has contrasting impacts on entanglement harvesting and mutual information harvesting in BTZ backgrounds: it enhances mutual information harvesting while suppressing entanglement harvesting. This phenomenon suggests that the increase in total correlations in Lorentz-violating vector field backgrounds with gravitational coupling is predominantly driven by classical components, with quantum correlations contributing less to the overall mutual information. These results indicate that Lorentz violation, as a quantum property of spacetime, may impose intrinsic constraints on the quantum information capacity encoded in spacetime due to competition among quantum degrees of freedom for resources. Furthermore, Lorentz symmetry breaking expands the $\textit{entanglement shadow}$ region, further demonstrating its disruptive effect on quantum correlations.

Xiaofang Liu

Wentao Liu

Zhilong Liu

Jieci Wang

Harvesting correlations from BTZ black hole coupled to a Lorentz-violating vector field