The ultra-compressed scotogenic regime, in which a 2 GeV mass splitting between the charged inert scalar and the dark-matter fermion is motivated by and compatible with co-annihilation to the observed relic density for suitable choices of the remaining model parameters, produces decay leptons for which existing LHC displaced-lepton and disappearing-track searches retain only partial, unoptimised acceptance, leaving room for a dedicated timing-assisted strategy. We propose exploiting the 30 ps timing resolution of the HL-LHC precision timing detectors as a fourth observable, converting the macroscopic scalar decay length of 100–1000 mm into an arrival-time delay of 70–700 ps – more than three orders of magnitude above the sub-picosecond delays of all prompt Standard Model backgrounds. Operating at the level of a low- $$p_T$$ disappearing-track stub matched to a delayed timing hit, without requiring full lepton reconstruction, our 4D timing strategy achieves signal efficiencies of 12–36% across the probed mass range (14% at the 200 GeV benchmark) and zero background across $$4.20\times 10^6$$ simulated prompt SM events, projecting 95% C.L. exclusion up to scalar masses of $$\simeq \!670$$ GeV at 3000 fb $$^{-1}$$ under conservative background assumptions. The scalar lifetime is set by the Yukawa coupling $\textit{y}$ through $$c\tau \propto y^{-2}$$ , while sub-eV neutrino masses constrain only the product $$y^2\lambda _5$$ ; the small couplings that place the charged scalar in the optimal timing window are therefore compatible with, though not uniquely fixed by, the radiative neutrino-mass mechanism, making the co-annihilation corridor – conventionally the most elusive regime – an accessible target for 4D spacetime tracking at the HL-LHC.

China

Renjie Wang

Probing ultra-compressed scotogenic dark matter at the HL-LHC via 4D spacetime tracking

The $$ f(T, T_G) $$ gravity theory is an extension of general relativity that incorporates the torsion scalar $$ T $$ as well as the teleparallel equivalent to the Gauss-Bonnet term $$ T_G $$ , to explore early and late time universe cosmology beyond the standard model. In this work, we obtain exact solutions of the field equations in the framework of $$ f(T, T_G) $$ gravity in the context of cosmological bouncing scenarios. For this, we explore the non-singular evolution of the universe by considering various bouncing cosmological models characterized by different scale factors such as the symmetric bounce, oscillatory bounce, superbounce, matter bounce, and singular bounce scenarios. For each scale factor model, we obtained the functional form of $$ f(T, T_G) $$ defining different ansatz like $$g(T)+h(T_G),~T_G~g(T)$$ and $$T+T_G ~g(T)$$ that satisfy the modified field equations and yields viable cosmological solutions. The analytical behaviors of the scale factor, Hubble parameter, energy density and pressure are examined to discuss the nature of the bounce and the avoidance of initial singularities. Our results demonstrate that the $$ f(T, T_G) $$ framework provides consistent and physically acceptable bouncing cosmologies capable of describing a smooth transition from contraction to expansion, thereby offering a viable alternative to inflationary models for the early universe.

Pakistan

Abdul Sultan

Ali Sabir

Malta

Jackson Said

Exact cosmological bouncing solutions in $$f(T,T_G)$$ gravity

The LUX-ZEPLIN (LZ) experiment is a direct-detection dark matter experiment, optimized to search for weakly interacting massive particles (WIMPs) through WIMP-nucleon interactions. The main challenge in dark matter detection is differentiating between WIMP signals and background events. In LZ, the ratio of ionization to scintillation signals (charge-to-light) is the primary method for rejecting electronic recoil (ER) background. Pulse shape discrimination (PSD) offers a method for additional ER backgrounds rejection in liquid xenon detectors. In this paper, the discrimination power of PSD with the LZ experiment is discussed. To precisely characterize the scintillation pulse shape, an analysis framework is developed to reconstruct the detection time of individual photons. Using LZ calibration data, the photon-timing tail fraction discriminator is optimized and achieves ER leakage as low as $$15\%$$ . For specific background processes such as $$^{124}$$ Xe double electron capture, the leakage is reduced further to about $$5\%$$ . PSD is combined with charge-to-light to form two-factor discrimination (TFD). The optimized TFD performance is compared with the performance of the charge-to-light method, with the corresponding false positive rate reduced by up to a factor of two for large scintillation pulses. Finally, PSD and TFD are applied to data from LZ’s WS2024 run and their performance is summarized.

United States

D. Akerib

United Kingdom

A. Al Musalhi

F. Alder

B. Almquist

C. Amarasinghe

A. Ames

T. Anderson

Switzerland

N. Angelides

H. Araújo

J. Armstrong

M. Arthurs

A. Baker

S. Balashov

J. Bang

J. Bargemann

E. Barillier

K. Beattie

A. Bhatti

T. Biesiadzinski

H. Birch

E. Bishop

G. Blockinger

C. Brew

Portugal

P. Brás

S. Burdin

M. Carmona-Benitez

M. Carter

A. Chawla

H. Chen

Y. Chin

N. Chott

S. Contreras

M. Converse

R. Coronel

A. Cottle

G. Cox

D. Curran

C. Dahl

I. Darlington

S. Dave

A. David

J. Delgaudio

S. Dey

L. Viveiros

L. Felice

C. Ding

J. Dobson

E. Druszkiewicz

S. Dubey

C. Dunbar

S. Eriksen

N. Fearon

N. Fieldhouse

S. Fiorucci

H. Flaecher

E. Fraser

Australia

T. Fruth

P. Gaemers

R. Gaitskell

A. Geffre

J. Genovesi

C. Ghag

J. Ghamsari

A. Ghosh

S. Ghosh

R. Gibbons

S. Gokhale

J. Green

M. Grinten

J. Haiston

C. Hall

T. Hall

R. Hampp

S. Haselschwardt

M. Hernandez

S. Hertel

G. Homenides

M. Horn

D. Huang

D. Hunt

E. Jacquet

R. James

K. Jenkins

A. Kaboth

A. Kamaha

M. Kannichankandy

D. Khaitan

A. Khazov

J. Kim

South Korea

Y. Kim

D. Kodroff

E. Korolkova

H. Kraus

S. Kravitz

L. Kreczko

V. Kudryavtsev

C. Lawes

E. Leon

D. Leonard

K. Lesko

Pushing the limits of pulse shape discrimination in a large liquid xenon detector

In this work, we derive the new hairy black hole solutions of the Lovelock-scalar gravity sourced by three different models of the nonlinear Yang–Mills field. First, we derive the Lovelock polynomial that deduces the nonlinear Yang–Mills black hole solution in a general Lovelock-scalar theory of gravity. Next, we determine the solutions that describe these objects in the context of Gauss–Bonnet-scalar and third order Lovelock-scalar theories. In addition, we examine the physical characteristics and the impact of nonlinear Yang–Mills field and scalar hair on the thermodynamic stability of resultant gravitating objects.

Askar Ali

Lovelock black holes dressed with a conformally coupled scalar field and nonlinear Yang–Mills charge

We investigate the dynamical critical behaviour of black hole phase transitions in anti de Sitter spacetime by extending the stochastic framework of free energy landscape dynamics to Kerr AdS black holes. By analyzing the Langevin evolution of the entropy (in contrast to the horizon radius in the RN-AdS case) near criticality, we demonstrate that the system exhibits pronounced critical slowing down, characterized by a significant increase of the autocorrelation time as the critical point is approached. This behaviour is further confirmed by the lowest eigenvalue of the Fokker–Planck equation. By analysing the dynamics along different thermodynamic paths, including variations in temperature, pressure, and angular momentum, and considering both directions – towards and away from criticality, we find that the relaxation time obeys a robust scaling relation, $$\tau =|\epsilon |^{-2/3}$$ near criticality. The same scaling exponent is obtained for RN-AdS, Kerr-AdS, and Bardeen black holes, suggesting the existence of an underlying universal dynamical behaviour across distinct black hole systems. Our results establish a connection between the geometry of the free energy landscape, stochastic nonequilibrium dynamics, and universal critical phenomena in black hole thermodynamics.

India

Mozib Awal

Prabwal Phukon

Critical slowing down of black hole phase transition and universal dynamic scaling in AdS black holes

NEXT-100 is a high-pressure xenon time projection chamber with electroluminescent amplification, designed to operate with up to $$\sim $$ 70.5 kg at 13.5 bar. It is the most recent detector developed by the NEXT collaboration to search for the neutrinoless double-beta decay ( $$\beta \beta 0\nu $$ ) of $$ ^{136}\mathrm Xe$$ . The NEXT gas TPC technology offers the best energy resolution near the Q-value of the decay ( $$Q_{\beta \beta }$$ = 2458 keV) among xenon detectors, which is set by design to be <1% FWHM. We report here the high-energy calibration of the detector using a $$ ^{228}\textrm{Th}$$ source, demonstrating excellent linear response and an energy resolution of $$(0.90 \pm 0.02)\%$$ FWHM at the $$^{208}$$ Tl photopeak (2615 keV). This performance extrapolates to a resolution at the double-beta decay end-point of $$R(Q_{\beta \beta }) = (0.93 \pm 0.02)\%$$ FWHM, confirming the detector’s capability for precision energy measurement in the search for $$\beta \beta 0\nu $$ .