It is notoriously difficult to construct a stable non-singular bouncing cosmology that avoids all possible instabilities throughout the entire evolution of the universe. In this work, we explore whether a non-singular bounce driven by a specific class of modifications of General Relativity, the vector-tensor generalized Proca theories, can be constructed without encountering any pathologies in linear perturbation theory. We find that such models unavoidably lead either to strong coupling in the tensor or the scalar sector, or instabilities in the matter sector during the bouncing phase. As our analysis is performed in a gauge-independent way, this result can be cast in the form of a no-go theorem for non-singular bounces with generalized Proca. In contrast to the no-go theorem found for Horndeski theories, however, it cannot be evaded by considering beyond generalized Proca theory. At the core of our result lies the non-dynamical nature of the temporal component of the vector field, which renders it an ill-suited mediator for a bouncing solution.

Switzerland

Lara Bohnenblust

Germany

Serena Giardino

Lavinia Heisenberg

Nadine Nussbaumer

To bounce or not to bounce in generalized Proca theory and beyond

The decrease of the chiral pseudocritical temperature <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>p</mi><mi>c</mi></mrow></msub></math> with an applied strong magnetic field has been extensively investigated by various QCD low-energy effective models and lattice QCD at the physical point. We find that this decreasing feature may not hold in the case with a weak magnetic field and still depends on quark masses: when the quark masses get smaller, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>p</mi><mi>c</mi></mrow></msub></math> turns to increase with the weak magnetic field. This happens due to the significant electromagnetic scale anomaly contribution in the thermomagnetic medium. We demonstrate this salient feature by employing the Nambu-Jona-Lasinio model with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2</mn><mo>+</mo><mn>1</mn></mrow></math> quark flavors including the electromagnetic scale anomaly contribution. We observe that at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><msub><mrow><mi>m</mi></mrow><mrow><mn>0</mn><mi>c</mi></mrow></msub><mo>,</mo><msub><mrow><mi>m</mi></mrow><mrow><mi>s</mi><mi>c</mi></mrow></msub><mo stretchy="false">)</mo><mo>≃</mo><mo stretchy="false">(</mo><mn>2</mn><mo>,</mo><mn>20</mn><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math> for the isospin symmetric mass for up and down quarks, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mn>0</mn></msub></math>, and the strange quark mass, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>s</mi></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>p</mi><mi>c</mi></mrow></msub></math> decreases with the magnetic field if the quark masses exceed the critical values, and increases as the quark masses become smaller. Related cosmological implications, arising when the supercooled electroweak phase transition or dark QCD cosmological phase transition is considered along with a primordial magnetic field, are also briefly addressed.

China

Yuanyuan Wang

Shinya Matsuzaki

Mamiya Kawaguchi

Japan

Akio Tomiya

Implications of the electromagnetic scale anomaly to the QCD chiral phase transition in the smaller quark mass regime: <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>p</mi><mi>c</mi></mrow></msub></math> does not drop with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>e</mi><mi>B</mi></math>

The default way of proving holographic entropy inequalities is the contraction method. It divides Ryu-Takayanagi (RT) surfaces on the ‘greater than’ side of the inequality into segments, then glues the segments into candidate RT surfaces for terms on the ‘less than’ side. Here we discuss how proofs by contraction are constrained and informed by entanglement wedge nesting (EWN)—the property that enlarging a boundary region can only enlarge its entanglement wedge. We propose that: (i) all proofs by contraction necessarily involve candidate RT surfaces, which violate EWN; (ii) violations of EWN in contraction proofs of maximally tight inequalities occur commonly and — where this can be quantified — with maximal density near boundary conditions; (iii) the non-uniqueness of proofs by contraction reflects inequivalent ways of violating EWN. As evidence and illustration, we study the recently discovered infinite families of holographic entropy inequalities, which are associated with tessellations of the torus and the projective plane. We explain the logic, which underlies their proofs by contraction. We find that all salient aspects of the requisite contraction maps are dictated by EWN while all their variable aspects set the scheme for how to violate EWN. We comment on whether the tension between EWN and contraction maps might help in characterizing maximally tight holographic entropy inequalities.

Bartłomiej Czech

Sirui Shuai

Nesting is not contracting

In general the speed of gravitational waves (GWs) in scalar-tensor modifications of Einstein’s gravity is different from the speed of light. Nevertheless, it has been measured that their speeds are nearly the same. For the most general scalar-tensor theories classified to date that do propagate a graviton—DHOST, including Horndeski and beyond Horndeski (BH) theories—we show that, remarkably, up to five self-consistent couplings of the scalar of dark energy (DE) to the photon are enough to make their GWs luminal in a wide set of cases. We find at least one luminal BH theory for which the GW decay into DE is suppressed in any cosmological background.

Russia

S. Mironov

A. Shtennikova

M. Valencia-Villegas

Luminal scalar-tensor theories for a not so dark dark energy

As the criterion for the applicability of the background subtraction method, not only the finiteness condition of the resulting Hamiltonian but also the condition for the validity of the first law of black hole thermodynamics can be reduced to the form amenable to much simpler analysis at infinity by using the covariant phase space formalism. With this, we further establish that the background subtraction method is as applicable as the covariant counterterm method not only to Einstein’s gravity, but also to its higher derivative corrections for black hole thermodynamics in both asymptotically flat and anti–de Sitter spacetimes. In addition, our framework also provides us with the first derivation of the universal expression of the Gibbs free energy in terms of the Euclidean on-shell action beyond Einstein’s gravity. Among others, our findings have a far reaching impact on the shift in methodology for the Euclidean approach to black hole thermodynamics, where the well justified background subtraction method by our wieldy criterion is supposed to be the favored choice compared to the covariant counterterm method.

Wei Guo

Xiyao Guo

Xin Lan

Hongbao Zhang

Wei Zhang

Background subtraction method is not only much simpler, but also as applicable as the covariant counterterm method

Hints of toponium might be incipient in LHC data, as given the vast numbers of <italic>t</italic> quarks produced, some survive on the exponential-decay tail long enough to fasten <math altimg='si1.svg'><mi>t</mi><mover accent='true'><mrow><mi>t</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math> together. I here discuss a few differences between the standard Quantum Chromodynamics (QCD) binding (the &#8220;glue&#8221;) and exotic short-range binding (the &#8220;nail&#8221;). If the binding energy below threshold reaches the 3 GeV range the peak of the <math altimg='si2.svg'><msub><mrow><mi>&#951;</mi></mrow><mrow><mi>t</mi></mrow></msub></math> is distinct enough that a cross-section dip should be apparent in the line shape, should there only be one isolated resonance, but is filled by the excited QCD states adding about a pbarn to the cross section of <math altimg='si1.svg'><mi>t</mi><mover accent='true'><mrow><mi>t</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math> production. Their effect for smaller binding energies is a tenuous increase in the cross section. A new-physics short-range interaction, on the other hand, yields a larger cross-section for equal binding energy (or hardly a visible bound state for similar cross section). This is due to its larger <math altimg='si1.svg'><mi>t</mi><mover accent='true'><mrow><mi>t</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math> relative wavefunction at small distances. Finally, assuming that standard QCD plays out, I comment on what size of constraints on new-physics coefficients one can expect at given precision.

Spain

Felipe J. Llanes-Estrada

Ensuring that toponium is glued, not nailed

Superstring theory on black-strings backgrounds, corresponding to deformed, rotating BTZ black holes, formed near <italic>k</italic> NS5 branes by <italic>p</italic> fundamental strings or <italic>negative</italic> strings, is inspected. For <italic>non</italic>-rotating black strings, in the positive case, it was shown in <cross-ref refid='br0220' id='crf0010'>[1]</cross-ref> that the excitation energy of a probe long string, plus its contribution to the black-string background, <math altimg='si2.svg'><mn>1</mn><mo stretchy='false'>/</mo><mi>p</mi></math> fraction of the black-string energy, is the same as that in <math altimg='si1.svg'><mi>T</mi><mover accent='true'><mrow><mi>T</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math> deformed <math altimg='si3.svg'><mi>C</mi><mi>F</mi><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math> with <math altimg='si4.svg'><mi>c</mi><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>6</mn><mi>k</mi></math>, if the <italic>B</italic>-field vanishes at the origin. This supports the claim that the black string can be thought of as a state in a symmetric product of <italic>p</italic> <math altimg='si3.svg'><mi>C</mi><mi>F</mi><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math>'s with central charge <math altimg='si4.svg'><mi>c</mi><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>6</mn><mi>k</mi></math>, where the black-string energy is split equally among all <italic>p</italic> factors. In <cross-ref refid='br0220' id='crf0020'>[1]</cross-ref>, it was not verified that this property persists in other cases. Here, we generalize the investigation of <cross-ref refid='br0220' id='crf0030'>[1]</cross-ref> to the superstring on deformed, <italic>rotating</italic> BTZ black holes, for both the positive and negative cases. We find the particular value of the <italic>B</italic>-field at the origin, for which the total energy of a probe long string, consisting of its excitation energy plus its contribution to the <math altimg='si2.svg'><mn>1</mn><mo stretchy='false'>/</mo><mi>p</mi></math> fraction of the black-string energy, is the same as that in <math altimg='si1.svg'><mi>T</mi><mover accent='true'><mrow><mi>T</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math> deformed <math altimg='si3.svg'><mi>C</mi><mi>F</mi><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math> with <math altimg='si4.svg'><mi>c</mi><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>6</mn><mi>k</mi></math>. Interestingly, the <italic>B</italic>-field required for this harmony with single-trace <math altimg='si1.svg'><mi>T</mi><mover accent='true'><mrow><mi>T</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math> holography, does <italic>not</italic> vanish at the origin in the <italic>rotating</italic> cases.

Israel

Amit Giveon

Daniel Vainshtein

To <italic>B</italic> or not to be in single-trace <math altimg='si1.svg'><mi>T</mi><mover accent='true'><mrow><mi>T</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math> holography

Deep learning-based object detection algorithms enable the simultaneous classification and localization of any number of objects in image data. Many of these algorithms are capable of operating in real-time on high resolution images, attributing to their widespread usage across many fields. We present an end-to-end object detection pipeline designed for rare event searches for the Migdal effect, at real-time speeds, using high-resolution image data from the scientific CMOS camera readout of the MIGDAL experiment. The Migdal effect in nuclear scattering, critical for sub-GeV dark matter searches, has yet to be experimentally confirmed, making its detection a primary goal of the MIGDAL experiment. The Migdal effect forms a composite rare event signal topology consisting of an electronic and nuclear recoil sharing the same vertex. Crucially, both recoil species are commonly observed in isolation in the MIGDAL experiment, enabling us to train YOLOv8, a state-of-the-art object detection algorithm, on real data. Topologies indicative of the Migdal effect can then be identified in science data via pairs of neighboring or overlapping electron and nuclear recoils. Applying selections to real data that retain 99.7% signal acceptance in simulations, we demonstrate our pipeline to reduce a sample of 20 million recorded images to fewer than 1000 frames, thereby transforming a rare search into a much more manageable search. More broadly, we discuss the applicability of using object detection to enable data-driven machine learning training for other rare event search applications such as neutrinoless double beta decay searches and experiments imaging exotic nuclear decays.

United States

J. Schueler

United Kingdom

H.M. Araújo

S.N. Balashov

Sweden

J.E. Borg

C. Brew

CERN

F.M. Brunbauer

C. Cazzaniga

A. Cottle

C.D. Frost

Finland

F. Garcia

D. Hunt

A.C. Kaboth

M. Kastriotou

I. Katsioulas

A. Khazov

P. Knights

H. Kraus

V.A. Kudryavtsev

S. Lilley

Portugal

A. Lindote

France

M. Lisowska

D. Loomba

M.I. Lopes

E. Lopez Asamar

P. Luna Dapica

P.A. Majewski

T. Marley

C. McCabe

L. Millins

A.F. Mills

M. Nakhostin

R. Nandakumar

T. Neep

F. Neves

K. Nikolopoulos

E. Oliveri

L. Ropelewski

V.N. Solovov

T.J. Sumner

J. Tarrant

E. Tilly

R. Turnley

R. Veenhof

Transforming a rare event search into a not-so-rare event search in real-time with deep learning-based object detection

We show that the general charged, rotating black hole in five-dimensional Einstein-Maxwell theory has a singular extremal limit. Only the known analytic solutions with exactly zero charge or zero angular momenta have smooth extremal horizons. We also consider general black holes in five-dimensional Einstein-Maxwell-Chern-Simons theory, and show that they also have singular extremal limits except for one special value of the coefficient of the Chern-Simons term (the one fixed by supergravity). Combining this with earlier results showing that extremal black holes have singular horizons in four-dimensional general relativity with small higher derivative corrections, and in anti-de Sitter space with perturbed boundary conditions, one sees that smooth extremal horizons are indeed the exception and not the rule.

Gary Horowitz

Jorge Santos

Smooth extremal horizons are the exception, not the rule

Models of inelastic (or pseudo-Dirac) dark matter commonly assume an accidental symmetry between the left-handed and right-handed mass terms in order to suppress diagonal couplings. We point out that this symmetry is unnecessary because for Majorana fermions the diagonal couplings are not strongly constrained. Removing the requirement of such an ad hoc symmetry instead relaxes the relic density constraint due to additional annihilation modes. We consider a simple UV-complete model realizing this setup and study constraints from (in)direct detection, beam dump experiments and colliders. We identify two viable mass regions for the dark matter mass, around a few hundred MeV and around a few GeV, respectively. The former region will be fully tested by near-future analyses of the NA64 and Belle II data, while the latter turns out to be challenging to explore even with future experiments.