We consider an experimentalist, Alice, who creates a quantum superposition of a charged or massive body outside of a black hole (or, more generally, in the presence of a Killing horizon). It was previously shown that emission of soft photons/gravitons into the black hole will result in the decoherence of the components of the superposition if it is held open for a sufficiently long span of time. However, at any finite time, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>t</mi><mi>c</mi></msub></math>, during the process, it is not obvious how much decoherence has irrevocably occurred. Equivalently, it is not obvious how much information an observer inside the black hole can extract about Alice’s superposition prior to time <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>t</mi><mi>c</mi></msub></math>. In this paper, we solve for the optimal experimental protocol to be followed by Alice for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>t</mi><mo>&gt;</mo><msub><mi>t</mi><mi>c</mi></msub></math> so as to minimize the decoherence of the components of her superposition. More precisely, given the entangling radiation that has passed through the horizon prior to the cross-section <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">C</mi></math> corresponding to the time <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>t</mi><mo>=</mo><msub><mi>t</mi><mi>c</mi></msub></math> in Alice’s lab, we determine the “optimal purification” of this radiation beyond <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">C</mi></math> such that the global quantum state of the radiation through the horizon has maximal overlap (quantum fidelity) with the Hartle-Hawking or Unruh vacuum. Due to the intricate low frequency entanglement structure of the quantum field theory vacuum state, we find this optimal purification to be nontrivial. In particular, even if Alice has already “closed” her superposition by bringing the components back together, we find that she can decrease the net decoherence of the components of her superposition somewhat by reopening it and performing further manipulations.

United States

Daine L. Danielson

Jonah Kudler-Flam

Gautam Satishchandran

Robert M. Wald

How to minimize the decoherence caused by black holes

We perform a thorough investigation of the universality of the long-distance matrix elements (LDMEs) of nonrelativistic QCD factorization based on a next-to-leading order (NLO) fit of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> color octet LDMEs to high transverse momentum <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>p</mi><mi>T</mi></msub></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><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></math> production data at the LHC. We thereby apply a novel fit-and-predict procedure to systematically take into account scale variations, and predict various observables never studied in this context before. In particular, the LDMEs can well describe <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> hadroproduction up to the highest measured values of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>p</mi><mi>T</mi></msub></math>, as well as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">ϒ</mi><mo stretchy="false">(</mo><mi>n</mi><mi>S</mi><mo stretchy="false">)</mo></mrow></math> production via potential nonrelativistic QCD based relations. Furthermore, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> production in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi><mi>γ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi><mi>p</mi></math> collisions is surprisingly reproduced down to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>p</mi><mi>T</mi></msub><mo>=</mo><mn>1</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, as long as the region of large inelasticity <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>z</mi></math> is excluded, which may be of significance in future quarkonium studies, in particular at the EIC and the high-luminosity LHC. In addition, our summary reveals an interesting pattern as to which observables still evade a consistent description.

Germany

Nora Brambilla

Mathias Butenschoen

China

Xiang-Peng Wang

How well does nonrelativistic QCD factorization work at next-to-leading order?

This paper presents a computer code for analyzing electroweak precision data (EWPD) in the framework of the Standard Model Effective Field Theory (SMEFT), highlights the importance of recent ATLAS and CMS precision measurements, and introduces a novel analysis of the forward–backward asymmetry at the LHC. The computer code provides the likelihood of SMEFT Wilson coefficients based on precision measurements of $\textit{W}$ and $\textit{Z}$ pole observables, interpolation formulas for Standard Model predictions, and modular SMEFT parametrizations. SMEFT predictions including next-to-leading-order (NLO) effects in perturbative and SMEFT expansion are available and five alternative electroweak input parameter schemes are supported. The likelihood addresses shortcomings of previous formulations in the treatment of parametric uncertainties and can be straightforwardly included in SMEFT fits of LHC data. The input parameter scheme dependence and role of NLO corrections is studied for the EWPD fit in the SMEFT. Furthermore, the impact of recent ATLAS and CMS measurements — of the $\textit{W}$ boson mass and width, of the lepton flavour universality (LFU) of $\textit{W}$ branching fractions, and the effective leptonic weak mixing angle, $$ {\sin}^2{\theta}_{\textrm{eff}}^{\ell } $$ — is analyzed. A test of LFU that surpasses the precision of existing measurements is proposed based on the $$ {\sin}^2{\theta}_{\textrm{eff}}^{\ell } $$ measurement. Finally, an ATLAS Drell-Yan triple-differential cross-section measurement is reinterpreted in the SMEFT and combined with the EWPD likelihood. This analysis demonstrates the feasibility of the LFU precision test, improves constraints on muon couplings with respect to the world average, and determines a combination of the quark-coupling asymmetry parameters $\textit{A}$ and $\textit{A}$ with a precision comparable to that of the heavy flavour parameters $\textit{A}$ and $\textit{A}$ .

Hannes Mildner

An EWPD SMEFT likelihood for the LHC — and how to improve it with measurements of W and Z boson properties

Knowledge of the pressure of cold and dense quark matter is known to significantly constrain the equation of state of neutron-star matter, a quantity playing a key role in deciphering the stars’ internal structure. In this Letter, we make important progress toward determining the last unknown contribution to the pressure at next-to-next-to-next-to-leading order in the strong coupling constant <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi>s</mi></msub></math>, available through the sum of all four-loop vacuum diagrams of dense quantum chromodynamics. We demonstrate the cancellation of both the covariant gauge parameter and all infrared divergences in the sum, showcasing the effective-field-theory paradigm in action. For the remaining infrared-finite four-loop integrals, we demonstrate the efficacy of the dense loop tree duality method—a novel numerical framework for multiloop calculations in thermal field theory. Together, our results show that completing the next-to-next-to-next-to-leading order pressure of cold quark matter is no longer merely possible but for the first time within reach.

Finland

Aapeli Kärkkäinen

Pablo Navarrete

Mika Nurmela

Risto Paatelainen

Kaapo Seppänen

Aleksi Vuorinen

Quark Matter at Four Loops: Hardships and How to Overcome Them

In AdS/CFT, two-sided black holes are described by states in the tensor product of two Hilbert spaces associated with the two asymptotic boundaries of the spacetime. Understanding how such a tensor product arises from the bulk perspective is an important open problem in holography, known as the factorisation puzzle. In this paper, we show how the Hilbert space of bulk states factorises due to non-perturbative contributions of spacetime wormholes: the trace over two-sided states with different particle excitations behind the horizon factorises into a product of traces of the left and right sides. This precisely occurs when such states form a complete basis for the bulk Hilbert space. We prove that the factorisation of the trace persists to all non-perturbative orders in 1$\textit{/G}$ , consequently providing a possible resolution to the factorisation puzzle from the gravitational path integral. In the language of von Neumann algebras, our results provide strong evidence that the algebra of one-sided observables transitions from a Type II or Type III algebra, depending on whether or not perturbative gravity effects are included, to a Type I factor when including non-perturbative corrections in the bulk.

Jan Boruch

Luca Iliesiu

Guanda Lin

Cynthia Yan

How the Hilbert space of two-sided black holes factorises

We study multiplicities and junctions of Bogomol’nyi-Prasad-Sommerfield domain walls interpolating between different chiral vacua in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>1</mn></math> supersymmetric QCD (SQCD) with the <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> gauge group and a varying number of fundamental quarks. Depending on the number of flavors <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>F</mi></math>, two distinct classes of degenerate domain walls emerge: (i) locally distinguishable, i.e., those which differ from each other locally, in local experiments; and (ii) those which have identical local structure and are differentiated only topologically, through judiciously chosen compactifications. In the first class, two-wall junctions exist, while in the second class, such junctions do not exist. Acharya and Vafa counted topologically distinguishable walls in pure super-Yang-Mills. Ritz, Shifman, and Vainshtein counted the locally distinguishable walls in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>F</mi><mo>=</mo><mi>N</mi></math> SQCD. In both cases, the multiplicity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>k</mi></math> walls was the same, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>ν</mi><mrow><mi>N</mi><mo>,</mo><mi>k</mi></mrow><mtext>walls</mtext></msubsup><mo>=</mo><mi>N</mi><mo>!</mo><mo>/</mo><mo stretchy="false">[</mo><mo stretchy="false">(</mo><mi>N</mi><mo>−</mo><mi>k</mi><mo stretchy="false">)</mo><mo>!</mo><mi>k</mi><mo>!</mo><mo stretchy="false">]</mo></math>. We study the general case <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0</mn><mo>≤</mo><mi>F</mi><mo>≤</mo><mi>N</mi></math>, with mixed sets of walls from both classes (i) and (ii) simultaneously, and demonstrate that the above overall multiplicity remains intact. We argue that the growth of the quark masses exhibits no phase transition at any finite mass. The locally distinguishable walls can turn into topologically distinguishable ones only at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>m</mi><mo>=</mo><mi>∞</mi></math>. The evolution of the low-energy wall world sheet theory in the passage from small to large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>m</mi></math> is briefly discussed. We also propose a candidate for the low-energy description of wall junctions. The tools used are localization of instantons, supersymmetry enhancement on the walls, and circle compactification.

Shi Chen

Evgenii Ievlev

Mikhail Shifman

Two types of domain walls in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>1</mn></math> super-QCD: How they are classified and counted

The physical phenomena seen by an observer are defined for a local inertial system that is subjective to the observer. Such a coordinate system is called a “moving frame” because it changes from time to time. However, unlike the Thomas precession, the Unruh-DeWitt detector has been discussed for a fixed frame. We discuss the Unruh-DeWitt detector by defining the vacuum for the moving frame, showing that the problem of the Stokes phenomenon can be solved by using the vierbeins and the exact WKB, to find factor 2 discrepancy from the standard result. Differential geometry is constructed in such a way that local calculations can be performed rigorously. If one expects Markov property, the calculation is expected to be local. The final piece that was missing was a local non-perturbative calculation, which is now complemented by the exact WKB. Our analysis defines a serious problem regarding the relationship between entanglement of the Unruh effect and differential geometry.

Japan

Tomohiro Matsuda

How to define the moving frame of the Unruh-DeWitt detector on manifolds

We investigate models that can induce significant modifications to the couplings of first- and second-generation quarks with Higgs bosons. Specifically, we identify all simplified models featuring two vector-like quark states which can lead to substantial enhancements in these couplings. In addition, these models generate operators in Standard Model Effective Field Theory, both at tree-level and one-loop, that are constrained by electroweak precision and Higgs data. We show how to evade constraints from flavour physics and consider direct searches for vector-like quarks. Ultimately, we demonstrate that viable ultraviolet models can be found with first-generation quark Yukawa couplings enhanced by several hundred times their Standard Model value, while the Higgs couplings to charm (strange) quarks can be increased by factors of a few (few tens). Given the importance of electroweak precision data in constraining these models, we also discuss projections for future measurements at the Tera-$\textit{Z}$ FCC-ee machine.

Italy

Barbara Erdelyi

Ramona Gröber

Nudžeim Selimović

How large can the light quark Yukawa couplings be?

Within the context of metric-affine gravity, we examine the significance of the boundary term in symmetric teleparallel gravity by employing the cosmological dynamical system analysis method. We focus on the novel gravity models characterized by the functions <math altimg='si1.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>Q</mi><mo>,</mo><mi>C</mi><mo stretchy='false'>)</mo></math>, where <italic>f</italic> is a smooth function of the non-metricity scalar <italic>Q</italic> and the associated boundary term <italic>C</italic>. In a cosmological setting adopting three different classes of symmetric teleparallel affine connections, we investigate a model <math altimg='si2.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>Q</mi><mo>,</mo><mi>C</mi><mo stretchy='false'>)</mo><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><msup><mrow><mi>Q</mi></mrow><mrow><mi>s</mi></mrow></msup><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi>e</mi><msup><mrow><mi>C</mi></mrow><mrow><mi>r</mi></mrow></msup></math>, and some special cases of this model. We show that the boundary term which is added to the Einsteinian field equations (or equivalently to <math altimg='si3.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>Q</mi><mo stretchy='false'>)</mo><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mi>Q</mi></math> ones) is capable of bringing forward solutions corresponding to the early accelerated expansion. This alludes the physics behind the boundary terms which usually are discarded in the most gravitational theories.

Iran

Hamid Shabani

Malaysia

Avik De

Tee-How Loo

The cosmological significance of boundary term in non-metricity gravity

WallGo is an open-source software designed to compute the bubble wall velocity in first-order cosmological phase transitions. Additionally, it evaluates the energy budget available for generating gravitational waves. The main part of WallGo, built in Python, determines the wall velocity by solving the scalar-field(s) equation of motion, the Boltzmann equations and energy-momentum conservation for the fluid velocity and temperature. WallGo also includes two auxiliary modules: WallGoMatrix, which computes matrix elements for out-of-equilibrium particles, and WallGoCollision, which performs higher-dimensional integrals for Boltzmann collision terms. Users can implement custom models by defining an effective potential and specifying a list of out-of-equilibrium particles and their interactions.

Sweden

Andreas Ekstedt

United Kingdom

Oliver Gould

Joonas Hirvonen

Canada

Benoit Laurent

Lauri Niemi

Switzerland

Philipp Schicho

Jorinde Vis

How fast does the WallGo? A package for computing wall velocities in first-order phase transitions