A low-mass right-handed neutrino could interact with electroweak bosons via mixing, a mediator particle, or loop corrections. Using an effective field theory, we determine constraints on these interactions from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math>-boson measurements at hadron colliders. Due to the difference in the initial states at the Tevatron and the LHC, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math>-boson decays to a right-handed neutrino would artificially increase the mass measured at the Tevatron while only affecting the difference between <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>W</mi><mo>+</mo></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>W</mi><mo>−</mo></msup></math> mass measurements at the LHC. Measurements from CDF and the LHC are used to infer the corresponding parameter values, which are found to be inconsistent between the two. The LHC experiments can improve sensitivity to these interactions by measuring the cosine of the helicity angle using <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math> bosons produced with transverse momentum above <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>≈</mo><mn>50</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>.

United Kingdom

Rodrigo Alonso

Michael Spannowsky

Sam Bates

Chris Hays

Chris Pollard

Sensitivity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math>-boson measurements to low-mass right-handed neutrinos

Realising $\textit{F}$ -term slow-roll inflation in supergravity is non-trivial due to the well-known $\textit{η}$-problem. The common strategy to solve the problem is to impose a shift symmetry on the Kähler potential, but this often leads to a negative potential in the large-field regime. To avoid negative potentials, an additional superfield called the stabiliser is usually added with a desired interaction. An alternative mechanism in supergravity, avoiding the use of a stabiliser superfield, was earlier proposed by two of us in the setup with a single chiral superfield having inflaton and goldstino amongst its field components. In this work, we extend that alternative mechanism to multi-superfield models of inflation, thereby providing a generic framework for embedding a wide class of single- and multi-field inflation models into supergravity. We illustrate our approach by several concrete examples of multi-field inflation and clarify the conditions required to avoid tachyonic instabilities during multi-field evolution. Our proposal significantly broadens the theoretical landscape of $\textit{F}$ -term inflation models in supergravity.

South Korea

Jinn-Ouk Gong

Japan

Russia

Sergei Ketov

Takahiro Terada

$\textit{F}$-term multi-field inflation in supergravity without stabiliser superfields

Exploring exotic matter around black holes (BHs) under different conditions, using equations of state and astrophysical observational data from BHs, may deepen our understanding of the nature of dark matter and theories of gravity. In the present work, we first briefly introduce a BH solution surrounded by a dust field in <italic>f</italic>( <italic>R, T</italic>) gravity and study the properties of the horizon around the BH. We investigate scalar invariants of the spacetime geometry, such as the Ricci scalar, the square of the Ricci tensor, and the Kretchman scalar. We also study the circular motion of test particles. Additionally, we investigate the effects of the dust field on the innermost stable circular orbits (ISCOs) and the particle&#8217;s energy and angular momentum at the ISCO. Moreover, we investigate particle oscillations near ISCO around the BH and calculate the frequencies of Keplerian orbits and vertical oscillations. As an astrophysical application of the studies, we study quasiperiodic oscillations (QPOs) in various QPO models. Finally, we obtain constraints on the dust field and BH parameters using a Monte Carlo Markov Chain (MCMC) simulation across the multidimensional parameter space for the microquasars GRO J1655-40 &amp; GRS 1915-105, the Milky Way, and the M82 X-1 galaxy.

Uzbekistan

Abubakir Shermatov

Javlon Rayimbaev

Sardor Murodov

Pakistan

Bushra Majeed

Inomjon Ibragimov

Bahran Shermatov

Erkaboy Davletov

Ikram Davletov

Circular motion and QPOs near BHs surrounded by dust fields in <italic>f</italic>( <italic>R, T</italic>) gravity

This article examines the impact of <math altimg='si24.svg'><mrow><mi>f</mi><mo>(</mo><mi mathvariant='script'>Q</mi><mo>)</mo></mrow></math> gravity parameters on analytical spherically symmetric solutions for compact objects. We employ two distinct metric ansatz to solve the equations of motion in <math altimg='si24.svg'><mrow><mi>f</mi><mo>(</mo><mi mathvariant='script'>Q</mi><mo>)</mo></mrow></math> gravity. To assess the feasibility and reliability of our models, we analyze various physical properties, including pressure, mass function, energy density, stability, adiabatic index, energy conditions, and hydrostatic equilibrium through a graphical framework. Additionally, we demonstrate how the mass-radius relation and stability are influenced by the <math altimg='si24.svg'><mrow><mi>f</mi><mo>(</mo><mi mathvariant='script'>Q</mi><mo>)</mo></mrow></math> theory parameter <italic>&#958;</italic> <inf>1</inf>. To validate our results, we estimate the radii of well-known compact objects, including PSR J0437-4715, 4U 1608-52, 2S 0921-630, SMC X-4, and Her X-1. Our analysis confirms that the obtained isotropic solutions are physically viable and exhibit significant clarity.

S. Ijaz

M.Z. Bhatti

Investigating compact stars in <math altimg='si24.svg'><mrow><mi>f</mi><mo>(</mo><mi mathvariant='script'>Q</mi><mo>)</mo></mrow></math> gravity: Analytical models and physical viability

In this paper, we identify a novel topological subclass, dubbed <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mover accent="true"><mi>W</mi><mo stretchy="false">˜</mo></mover><mrow><mn>1</mn><mo>+</mo></mrow></msup></math>, in the thermodynamics of higher odd-dimensional, multiply rotating Kerr anti–de Sitter (AdS) black holes. This discovery extends the established topological classification beyond the five classes and two subclasses previously known. The <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mover accent="true"><mi>W</mi><mo stretchy="false">˜</mo></mover><mrow><mn>1</mn><mo>+</mo></mrow></msup></math> subclass exhibits a unique and previously unreported stability profile: it admits a thermodynamically stable small black hole state in the low-temperature limit, while in the high-temperature limit, the phase space simultaneously contains one stable large black hole, one stable small black hole, and one unstable small black hole state. Our analysis, which treats black hole solutions as topological defects, reveals a richer landscape of black hole thermodynamics than previously understood and necessitates an expansion of the topological classification scheme to accommodate this new phenomenology.

China

Wangyu Ai

Di Wu

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mover accent="true"><mi>W</mi><mo stretchy="false">˜</mo></mover><mrow><mn>1</mn><mo>+</mo></mrow></msup></math> subclass: Extending the topological classification of black hole thermodynamics

The particle origin of dark matter (DM) remains elusive despite decades of direct, indirect, and collider searches. Several groups have reported a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi></math>-ray excess toward the Galactic Center commonly referred to as the Galactic Center excess (GCE). Its spectrum is consistent with annihilation of weakly interacting massive particles (WIMPs) of mass <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><mn>10</mn><mo>−</mo><mn>100</mn><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math> and a thermal-relic cross section. Although many concrete WIMP models reproduce the GCE spectrum, most are now excluded by direct detection experiments that are approaching the neutrino floor. We investigate a class of anomaly-free extensions of the Standard Model featuring gauged differences of lepton number, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mo stretchy="false">)</mo><mrow><msub><mi>L</mi><mi>i</mi></msub><mo>−</mo><msub><mi>L</mi><mi>j</mi></msub></mrow></msub></math>, and gauged baryon minus lepton number, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mo stretchy="false">)</mo><mrow><mi>B</mi><mo>−</mo><mi>L</mi></mrow></msub></math>. We show that these models can reproduce the GCE while remaining compatible with the observed relic abundance. We then impose collider and direct detection constraints, accounting for both tree-level and loop-induced kinetic mixing. The <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>e</mi></msub></math> model gives the best fit to the GCE: a DM mass of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>χ</mi></mrow></msub><mo>∼</mo><mn>40</mn><mo>−</mo><mn>50</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math> remains consistent with the muon and electron magnetic moment anomalies, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><mi>g</mi><mo>−</mo><mn>2</mn><msub><mo stretchy="false">)</mo><mrow><mi>μ</mi><mo>,</mo><mi>e</mi></mrow></msub></math>, as well as current collider and direct detection limits, for mediator masses in the range <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>m</mi></mrow><mrow><msup><mrow><mi>A</mi></mrow><mrow><mo>′</mo></mrow></msup></mrow></msub><mo>∼</mo><mn>70</mn><mo>−</mo><mn>86</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math> and a DM mediator coupling of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>1</mn><mo>−</mo><mn>5</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></math>. By contrast, the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>e</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></math> models yield poorer fits; satisfying both the relic density and experimental bounds forces the DM mass to lie very close to resonance (i.e. approximately half the mediator mass). Finally, while the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo>−</mo><mi>L</mi></math> model also matches the GCE well, its parameter space is almost entirely ruled out by strong direct detection limits, except for the narrow resonance region where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>χ</mi></msub></math> should be equal to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><msup><mi>A</mi><mo>′</mo></msup></msub><mo>/</mo><mn>2</mn></math> requiring a fine-tuning at the few-percent level.

Italy

Jordan Koechler

Mattia Di Mauro

Leptophilic dark matter in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mo stretchy="false">)</mo><mrow><msub><mi>L</mi><mi>i</mi></msub><mo>−</mo><msub><mi>L</mi><mi>j</mi></msub></mrow></msub></math> models: A solution to the Fermi-LAT Galactic Center excess consistent with cosmological and laboratory observations

In this study, we investigate the inflationary dynamics of Rainbow <italic>f</italic>( <italic>R</italic>) gravity characterized by <italic>f</italic>( <italic>R</italic>)&#8239;&#8771;&#8239; <italic>&#945;Rn</italic>, with the rainbow deformation <math altimg='si8.svg'><mrow><mover accent='true'><mi>f</mi><mo>&#732;</mo></mover><mrow><mo>(</mo><mi>H</mi><mo>)</mo></mrow><mo>&#8764;</mo><msup><mi>H</mi><mi>&#955;</mi></msup></mrow></math> and <math altimg='si9.svg'><mrow><mover accent='true'><mi>g</mi><mo>&#732;</mo></mover><mo linebreak='goodbreak'>=</mo><mn>1</mn></mrow></math>. The effects of the rainbow parameter <italic>&#955;</italic> and the curvature exponent <italic>n</italic> on inflationary observables are analyzed under the Atacama Cosmology Telescope (ACT) constraint 0.9709&#8239;&lt;&#8239; <italic>n<inf>s</inf></italic>&#8239;&lt;&#8239;0.9777. Numerical results reveal a clear correlation among <italic>n, &#955;</italic>, and the tensor-to-scalar ratio <italic>r</italic>, such that decreasing <italic>n</italic> corresponds to increasing <italic>&#955;</italic>, accompanied by a growth in <italic>r</italic> within observational limits. Negative values of <italic>&#955;</italic> (typically for <italic>n</italic>&#8239;&#8776;&#8239;3) yield a quasi&#8211;de Sitter inflationary phase with a nearly constant Hubble parameter and suppressed tensor modes, while positive <italic>&#955;</italic> (for <italic>n</italic>&#8239;&#8818;&#8239;2.2) drive a quintessence&#8211;like inflationary regime with enhanced expansion and a time-dependent curvature. Using power&#8211;law solutions <italic>a</italic>( <italic>t</italic>)&#8733; <italic>tp</italic>, we relate the expansion exponent to the number of <italic>e</italic>-folds <italic>N</italic>&#8239;&#8771;&#8239;50&#8211;60. Small deviations between the matter and effective equations of state indicate a mild breaking of <math altimg='si10.svg'><mrow><msub><mi>w</mi><mi>e</mi></msub><mo linebreak='goodbreak'>=</mo><mi>w</mi></mrow></math>, suggesting the emergence of matter&#8211;like behavior within the quintessence&#8211;like inflationary field. At low curvature, we further show that a logarithmic Nojiri&#8211;Odintsov correction <italic>f</italic>( <italic>R</italic>)&#8239;&#8771;&#8239; <italic>&#945;</italic>&#8242;ln&#8201;( <italic>R</italic>/ <italic>&#956;</italic> 2) naturally dominates the dynamics, giving rise to a late&#8211;time quintessence phase ( <math altimg='si11.svg'><mrow><mo>&#8722;</mo><mn>1</mn><mo linebreak='goodbreak'>&lt;</mo><msub><mi>w</mi><mi>e</mi></msub><mo linebreak='goodbreak'>&lt;</mo><mo>&#8722;</mo><mn>1</mn><mo linebreak='goodbreak'>/</mo><mn>3</mn></mrow></math> for <math altimg='si12.svg'><mrow><mi>&#955;</mi><mo linebreak='goodbreak'>&gt;</mo><mo>&#8722;</mo><mn>1</mn></mrow></math>) that asymptotically approaches a de Sitter attractor ( <math altimg='si13.svg'><mrow><msub><mi>w</mi><mi>e</mi></msub><mo>&#8594;</mo><mo>&#8722;</mo><mn>1</mn></mrow></math> as &#1013; <inf>1</inf>&#8239;&#8594;&#8239;0 or <math altimg='si14.svg'><mrow><mi>&#955;</mi><mo linebreak='goodbreak'>=</mo><mo>&#8722;</mo><mn>1</mn></mrow></math>). Thus, the combined <italic>Rn</italic> and logarithmic contributions provide a unified geometric framework in which early&#8211;time inflation and late&#8211;time cosmic acceleration naturally arise from different curvature regimes of Rainbow <italic>f</italic>( <italic>R</italic>) gravity, consistent with ACT observational data.

Türkiye

A.I. Keskin

Rainbow <italic>f</italic>( <italic>R</italic>) Inflation: de Sitter-Quintessence Phases

The analysis of the latest most accurate experimental data on neutron decay for the possibility of the existence of the right vector boson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mi>W</mi><mi>R</mi></msub></mrow></math> is carried out. As a result of the analysis within the framework of the left-right symmetric model, it was found that there is an indication of the existence of the right vector boson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mi>W</mi><mi>R</mi></msub></mrow></math> with a mass of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mi>M</mi><mrow><msub><mi>W</mi><mi>R</mi></msub></mrow></msub><mo>=</mo><msubsup><mn>304</mn><mrow><mo>−</mo><mn>20</mn></mrow><mrow><mo>+</mo><mn>24</mn></mrow></msubsup><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>, and a mixing angle with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mi>W</mi><mi>L</mi></msub></mrow></math>: <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ζ</mi><mo>=</mo><mo>−</mo><mn>0.039</mn><mo>±</mo><mn>0.0</mn><mn>1</mn><mn>4</mn></mrow></math>. It is shown that this result does not contradict the experiments at colliders to search for a hypothetical vector boson. In addition, it is shown that it is possible to describe the effects of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>C</mi><mi>P</mi></mrow></math> violation in decays of neutral <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi></math>-mesons and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi></math>-mesons using the parameters of the extended left-right symmetric model obtained from neutron decay, i.e., squared masses of the left and right bosons ratio and the mixing angle. The formation of baryon-lepton asymmetry of the Universe is considered within the framework of the left-right model of weak interaction with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>C</mi><mi>P</mi></mrow></math> violation.

A.P. Serebrov

O.M. Zherebtsov

A.K. Fomin

R.M. Samoilov

N.S. Budanov

Analysis of experimental data on neutron decay for the possibility of the existence of the right vector boson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>W</mi><mi>R</mi></msub></math>

We revisit the calculation of exclusive <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> production in electron-proton scattering within the QCD dipole model, employing a refined description of the proton in terms of gluonic hot spots in the dilute regime. In contrast to earlier studies, we incorporate key missing elements; the event-by-event fluctuations in both the number of hot spots and their local saturation scales, as well as the first relativistic corrections to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> wave function. We perform a Bayesian analysis to constrain the model parameters using HERA data. These enhancements significantly improve the agreement with HERA data. Saturation scale fluctuations are found to be more important than fluctuations in the number of hot spots. Including the first relativistic correction is found to be important, especially in order to describe the observed power-law behavior in the incoherent cross section at large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>t</mi></math>.

Finland

Anh Dung Le

Heikki Mäntysaari

Exclusive <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> production off a dilute proton within a refined hotspot description

Based on available experimental results on $ \chi _{cJ}(J=0,1,2) $ decays, we investigated the $ \chi_{cJ}\to PP $ , $ VV $ , $ PV $ , and $ PT $ decays using the $\textit{SU}$(3) flavor symmetry/breaking approach, where $\textit{P}$, $\textit{V}$, and $\textit{T}$ denote light pseudoscalar, vector, and tensor mesons, respectively. With the decay amplitude relations determined by $\textit{SU}$(3) flavor symmetry/breaking, we present the branching ratios for all $ \chi_{cJ}\to PP $ and $ \chi_{cJ}\to VV $ modes, including those without experimental data. While theoretical considerations strongly suppress or even forbid most $ \chi_{cJ}\to PV $ and $ PT $ decays, we also provide quantitative predictions constrained by existing experimental data. Our results are expected to be accessible in future experiments at BESIII and the planned Super Tau-Charm Facility.

Bo Lan

Qin-Ze Song

Jin-Huan Sheng

Yi Qiao

Ru-Min Wang

Study of χ$_{cJ}$ ($\textit{J}$ = 0,1,2) decays to light meson pairs based on $\textit{SU}$(3) flavor symmetry/breaking analysis * Supported by the National Natural Science Foundation of China (12175088, 12305100, 12365014) and Graduate Innovation Fund Project of Jiangxi Provincial Department of Education (YJS2024091)