Peer Revenue Fully funded

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics High Energy Physics (Phenomenology)

hep-ph Watch High Energy Physics (Phenomenology)

Tuesday 15 September

High Energy Physics (Phenomenology)

Taking dimuon production in DIS to NNLO precision

Ilkka Helenius, Hannu Paukkunen and Sami Yrjänheikki

We present an updated calculation of dimuon production in neutrino-nucleus collisions - an important constraint of the relatively poorly-known strange-quark distribution - at next-to-next-to-leading (NNLO) order. Compared to the approach usually used in the literature, where one computes inclusive charm production and multiplies the cross section by corrective factors, we instead compute the dimuon production cross section directly using semi-inclusive deep inelastic scattering (SIDIS) and a data-fitted decay function. While inclusive charm production has previously been computed to NNLO, we are using the recently-computed NNLO SIDIS coefficients to calculate the perturbative parts of the entire dimuon production process at NNLO. We find a notable reduction of scale uncertainties at larger momentum-fraction $x$, where the NNLO corrections tend to increase the cross section. At smaller $x$, we find a decrease in the cross section, a behaviour which can be linked to the suppression of the strange sea and which may eventually alleviate the tension observed between dimuon neutrino and LHC heavy-gauge boson data.
Read the full abstract

High Energy Physics (Phenomenology) · Cross-listed from nucl-th

Alpha-Core Breakup in the Strong Decay of \({}_{\Lambda\Lambda}^{6}\mathrm{He}\) to a Deeply Bound \(H\) Dibaryon

Mahboubeh Shahrbaf and Makoto Oka

We investigate the effect of $\alpha$-core breakup on the strong conversion of \({}^{6}_{\Lambda\Lambda}\mathrm{He}\) into a deeply bound \(H\) dibaryon. In addition to the coherent \(H+{}^{4}\mathrm{He}\) channel, we evaluate the open final states \(H+p+{}^{3}\mathrm{H}\), \(H+n+{}^{3}\mathrm{He}\), and \(H+d+d\) using a translationally invariant Gaussian cluster description, including spin-isospin recoupling and full nonrelativistic three-body phase-space integrations. The breakup widths are normalized to Gal's intact-\(\alpha\) result. At \(B_{\Lambda\Lambda}^{H}=176~\mathrm{MeV}\), corresponding to \(m_H\simeq2055~\mathrm{MeV}\), the summed breakup width exceeds the intact-\(\alpha\) width by a factor \(R_{\mathrm{br}}=2.49\times10^{3}\). The resulting inclusive width and lifetime are \(\Gamma_{\mathrm{inc}}=3.87\times10^{-4}~\mathrm{eV}\) and \(\tau_{\mathrm{inc}}=1.70\times10^{-12}~\mathrm{s}\), respectively, compared with \(\tau_{\alpha}=4.25\times10^{-9}~\mathrm{s}\) for the intact-\(\alpha\) channel alone. The mass-dependent calculation shows that the inclusive lifetime crosses the characteristic hypernuclear weak-decay timescale near \(m_H\simeq2020~\mathrm{MeV}\) and increases rapidly as the \(H\) mass decreases. In the representative dark-matter-motivated interval \(1865\leq m_H\leq1885~\mathrm{MeV}\), we obtain \(6.59\times10^{-4}\lesssim\tau_{\mathrm{inc}}\lesssim 6.80\times10^{-3}~\mathrm{s}\), far exceeding the weak-decay timescale. Thus, although core breakup can dominate the inclusive strong width near \(m_H\simeq2055~\mathrm{MeV}\), weakly decaying double-\(\Lambda\) hypernuclei remain compatible, within the present framework, with a deeply bound \(uuddss\) state in the mass range relevant to sexaquark dark matter.
Read the full abstract

High Energy Physics (Phenomenology)

Radiative decays of the predicted P-wave $D\bar{D}^*$ molecular state: the $0^{-+}$ case

Qi Wu, Ming-Qi Cui, Zi-Li Yue et al. (+3 more)

In the present work, we study the radiative decays of the P-wave $D\bar{D}^*$ molecular state $G_0$ with $I^G(J^{PC})=0^+(0^{-+})$ using a phenomenological Lagrangian approach. The molecular coupling is fixed by the compositeness condition with a Gaussian form factor. The partial widths for $G_0\to \gamma\gamma$, $\gamma J/\psi$, $\gamma \psi(2S)$, $\gamma h_c$, $\gamma \rho$, and $\gamma \omega$ are evaluated. Our results show that the two-photon and $\gamma h_c$ channels are highly suppressed, while $\gamma J/\psi$, $\gamma \psi(2S)$, and $\gamma \rho$ are of the order of a few keV, and $\gamma \omega$ reaches several tens of keV, making it the dominant radiative mode. The ratios $\Gamma(G_0 \to \gamma \psi(2S))/\Gamma(G_0 \to \gamma J/\psi)$ and $\Gamma(G_0 \to \gamma \omega)/\Gamma(G_0 \to \gamma \rho)$ are predicted to be 1-2.6 and 3.4-5.4, respectively, with mild parameter dependence. We also compare with hadronic decays and find that the total radiative decay width is lower than the hadronic decay widths by about one order of magnitude. We propose searching for $G_0$ in the sequential decay $Y(4230)\to \gamma G_0 \to \gamma\omega J/\psi$, which is accessible to further experimental measurements by the BESIII, Belle II and LHCb Collaborations.
Read the full abstract

All authors Qi Wu, Ming-Qi Cui, Zi-Li Yue, Dian-Yong Chen, Shi-Dong Liu, Gang Li

High Energy Physics (Phenomenology)

Multiplicative NLO matching in DIS with Pythia 8

Ilkka Helenius, Joni O. Laulainen and Christian T. Preuss

We present a new multiplicative next-to-leading order (NLO) matching scheme in Pythia 8 for deep-inelastic scattering (DIS) processes in electron-proton collisions. The implementation is based on numerical event-by-event integration over the virtual corrections and real-emission phase-space and matrix-element corrections (MECs) for the first parton-shower emission. The latter has been included for two parton-shower options currently available in Pythia 8 to handle DIS processes, the default shower with dipole-recoil option and Vincia. The implementation has been validated against other available NLO-capable event generators and compared to experimental data from the HERA collider. In all cases we find very good agreement confirming the validity of the new Pythia implementation. We also study the impact of the MECs in each shower and consider the implications for the upcoming Electron-Ion collider.
Read the full abstract

High Energy Physics (Phenomenology)

Quark fracture function at small $x$ from the Color Glass Condensate

Paul Caucal, Nolann Juet and Farid Salazar

The target-fragmentation region in deeply inelastic electron-nucleus scattering provides insight into the partonic structure of the target, as hadrons measured in the final state retain information about the nonperturbative dynamics of spectator partons inside the nucleus. In QCD factorization theorems, this nonperturbative dynamics is encoded in objects known as fracture functions. In this paper, we study the extended quark fracture function in the limit where the struck (anti)quark carries a very small longitudinal momentum fraction, $x$. We first present an elementary derivation within the Color Glass Condensate effective field theory of the quark fracture function in terms of the dipole operator at small $x$. At the parton level, the quark extended fracture function is sensitive to gluon saturation when the transverse momentum $P_\perp$ of the outgoing parton produced in the target-fragmentation region is smaller than the nuclear saturation scale $Q_s$, in which regime the $P_\perp$ distribution becomes approximately flat. We then show, through a numerical study that incorporates the convolution of this parton-level result with a collinear fragmentation function, that hadronization largely washes out these saturation effects, as the convolution predominantly probes partonic transverse momenta that are typically larger than $Q_s$.
Read the full abstract

High Energy Physics (Phenomenology)

Matching relations for gluon TMDs up to one-loop accuracy

Alessio Carmelo Alvaro, Nanako Kato, Barbara Pasquini et al. (+2 more)

We present new results on the matching relations for gluon transverse momentum dependent parton distribution functions up to one-loop accuracy. At tree-level, employing the spinor formalism, we obtain these relations up to twist 3 accuracy for both T-even and T-odd distributions, including the hadron-mass corrections. At one-loop order, we extend the parton-in-parton approach to include higher-twist operators in the small-$b$ expansion. As a result, we derive for the first time the Wandzura-Wilczek relation for the worm-gear T distributions and establish a systematic method to include mass corrections at one-loop and twist-2 accuracies.
Read the full abstract

All authors Alessio Carmelo Alvaro, Nanako Kato, Barbara Pasquini, Cristian Pisano, Simone Rodini

High Energy Physics (Phenomenology) · Cross-listed from hep-th

Positivity Bounds in $\mathcal N =1$ Supersymmetry

Jingxuan Bu, Jiayin Gu and Runqing Wang

For a low-energy Effective Field Theory (EFT) to admit a consistent ultraviolet (UV) completion, it must adhere to the fundamental principles of locality, unitarity, analyticity, and Lorentz invariance. This leads to positivity constraints on certain Wilson coefficients via dispersion relations of $2\rightarrow2$ forward elastic amplitudes, which carry significant implications for both theoretical consistency and experimental phenomenology. In this work, we extend this bootstrap framework to $\mathcal N = 1$ supersymmetric theories, where the super-Poincaré algebra relates the bosonic and fermionic degrees of freedom within a single supermultiplet. Supersymmetric Ward identities (SWIs) enforce exact linear relations among component scattering amplitudes. Consequently, the Wilson coefficients associated with different $2\rightarrow2$ processes are mutually constrained, rendering their respective positivity bounds dependent. Focusing on dimension-8 operators, we explicitly show the positivity bounds on quartic interactions involving scalars, fermions and gauge fields, and demonstrate how they are related as a direct consequence of the SWIs. Furthermore, we expect that the algebraic nature of this framework naturally extends to loop-level superamplitudes and higher-point processes, providing a unified bootstrap perspective on supersymmetric EFTs.
Read the full abstract

High Energy Physics (Phenomenology)

Double parton scattering off nuclei and the double-EMC effect

Filippo Fornetti, Federico Alberto Ceccopieri, Emanuele Pace et al. (+2 more)

The double-parton scattering process off light and heavy nuclei is proposed as an effective tool to open a novel window for accurately studying the effects of nuclear binding on the internal structure of the nucleon, in the spirit of the European Muon Collaboration (EMC) effect. The key ingredient is the actual calculation of nuclear double-parton distributions that contain information about double-parton distributions and generalized-parton distributions of the nucleon, folded with nuclear light-front distributions. It allows to introduce a new quantity, which we call double-EMC ratio that appears to be much more sensitive than the standard EMC effect to both the nucleon partonic structure and to the nuclear binding. Hence, it could help solving long-standing questions about how nucleons change when they are bound in atomic nuclei.
Read the full abstract

All authors Filippo Fornetti, Federico Alberto Ceccopieri, Emanuele Pace, Matteo Rinaldi, Giovanni Salmè

High Energy Physics (Phenomenology) · Cross-listed from nucl-ex

Exploring nucleon spin by Drell-Yan process

Wen-Chen Chang

Contributions of parton's orbital motion to the nucleon spin are encoded in the transverse-momentum dependent distributions (TMDs) and generalized parton distributions (GPDs). Currently these distributions are accessed through the lepton-induced processes such as semi-inclusive deep-inelastic scattering (SIDIS) and deeply virtual Compton Scattering (DVCS). The (un)polarized Drell-Yan process with hadron beams provides a unique and complementary probe, enabling critical tests of the universality properties of TMDs and GPDs in the space-like and time-like approaches. This talk reviews recent results of TMDs obtained from the Drell-Yan measurements and discusses future prospects for accessing nucleon GPDs through measurements of the exclusive pion-induced Drell-Yan process at J-PARC.
Read the full abstract

High Energy Physics (Phenomenology)

Glueballs: hadrons without quarks

Cyrille Chevalier and Vincent Mathieu

Glueballs are colour-singlet bound states built from gluons alone. They are an unavoidable consequence of the non-Abelian structure of Quantum Chromodynamics (QCD), and, in the pure Yang–Mills limit, they are the only physical excitations of the theory. The present article reviews what is known about them. After establishing which spin, parity and charge-conjugation quantum numbers two- and three-gluon states can carry, the pure-gauge spectrum is surveyed. Each of the main theoretical approaches and their respective conclusions are briefly presented. They include lattice QCD, constituent-gluon and Coulomb-gauge models, functional Dyson–Schwinger and Bethe–Salpeter equations, holographic models, and QCD sum rules. Particular attention is paid to the scale-setting ambiguity that limits how precisely a quenched glueball mass can be converted into physical units. The discussion then turns to full QCD. After discussing the meaning of a glueball assignment in this context, unquenching effects and questions related to glueball–$q\bar{q}$ mixing are addressed. The large-$N_c$ counting that underpins the mixing picture, as well as mass-matrix and effective-Lagrangian treatments of mixing are presented. The selection rules and dynamical mechanisms that shape glueball decays are also discussed. The gluon-rich production mechanisms used experimentally are finally reviewed. The candidates are assessed sector by sector: $f_0(1370)/f_0(1500)/f_0(1710)$ and the competing interpretations of the scalar sector, $\eta(1405)/\eta(1475)$ and $X(2370)$ in the pseudoscalar sector, the crowded tensor region, and the essentially unexplored $C=-1$ sector and its connection to the Odderon. Outlooks on the programmes that could help in validating some of these candidates or identifying others are reviewed as a conclusion.
Read the full abstract

High Energy Physics (Phenomenology)

Weak Decays of the $\Lambda_{b}$ Baryon in Light-Front Dynamics

Chong-Chung Lih, Cong-Yu Li and Chao-Qiang Geng

We investigate the exclusive semileptonic and nonleptonic $\Lambda_{b} \to \Lambda_{c}(p)$ decays within the Standard Model by using the light-front quark model. To determine the behavior of the $\Lambda_{b} \to \Lambda_{c}(p)$ transition form factors, we employ the Bethe-Salpeter formalism in the timelike region, effectively accounting for both valence and nonvalence contributions. Using these form factors, including nonvalence contributions, we obtain branching fractions of $\Lambda_b \to \Lambda_c\,\ell\,\bar{\nu}_{\ell}$, $\Lambda_b \to \Lambda_c\,\tau\,\bar{\nu}_{\tau}$, $\Lambda_b \to p\,\ell\,\bar{\nu}_{\ell}$ and $\Lambda_b \to p\,\tau\,\bar{\nu}_{\tau}$~($\ell=e$ or $\mu$) are found to be around $5.39\%$, $1.41\%$, $3.33\times 10^{-4}$ and $2.08\times 10^{-4}$, respectively, which are consistent with the experimental measurements. The ratios of $R^{\ell\tau}(\Lambda_{c})=\frac{{\cal B}({\Lambda_b}\to {\Lambda_c}\,\tau\,\bar{\nu}_\tau)} {{\cal B}({\Lambda_b}\to {\Lambda_c}\,\ell\,\bar{\nu}_l)}$ and $R^{\ell\tau}(p)=\frac{{\cal B}({\Lambda_b}\to p\,\tau\,\bar{\nu}_\tau)} {{\cal B}({\Lambda_b}\to p\,\ell\,\bar{\nu}_l)}$, are given by $0.261^{+0.097}_{-0.117}$ and $0.624^{+0.119}_{-0.129}$, respectively. The forward-backward asymmetries in the above semilepton decays are also examined. Our results indicate that, within the light-front framework, the nonvalence contributions to the asymmetries are negligible compared to the $\beta$-induced uncertainties. In addition, we calculate the branching ratios for the nonleptonic decays of $\Lambda_{b}\to \Lambda_{c}(p)\,M$ with $M$ being the pseudo scalar and vector mesons with the results found to be consistent with the current experimental data.
Read the full abstract

High Energy Physics (Phenomenology)

Probing the Tau Neutrino Magnetic Moment via the $\mu^{-}\gamma \rightarrow \mu^{-}\nu\bar{\nu}$ Process at Future Muon Colliders

D. Yilmaz, M. Sahin and I. Sahin

We investigate the sensitivity of future muon colliders to the anomalous magnetic moment of the tau neutrino within a model-independent effective field theory framework. The analysis is performed through the subprocess $\mu^{-}\gamma \rightarrow \mu^{-}\nu\bar{\nu}$ where the initial-state photon is described using the Equivalent Photon Approximation. Signal and background events are generated with MadGraph5$\_$aMC$@$NLO, followed by parton showering and hadronization with PYTHIA8. Detector effects are simulated using DELPHES3, while the event reconstruction and analysis are carried out via the MadAnalysis5 framework. Optimized kinematic selection criteria are determined for center-of-mass energies of 3, 10 and 30 TeV muon colliders. The expected sensitivities are evaluated using the Asimov significance method. The best sensitivity is obtained for the 30 TeV muon collider option, where the anomalous magnetic moment of the tau neutrino can be probed down to $\mu_{\tau\tau}=5.21\times10^{-8}\,\mu_B$ at the 5$\sigma$ significance level assuming a 1% systematic uncertainty. Our sensitivity bounds improve the current direct experimental limit reported by the DONUT Collaboration up to one order of magnitude and demonstrate the strong potential of future muon colliders for probing neutrino electromagnetic interactions.
Read the full abstract

High Energy Physics (Phenomenology)

Probing Local Charm Hadronization Dynamics with Hadron-Anchored Energy Correlators

Robert Vertesi

We introduce the hadron-anchored energy correlator (HAEC), a jet-restricted realization of the fragmentation energy correlator and the semi-inclusive energy correlator frameworks, and apply it to heavy-flavor-tagged jets in hadron collisions. Using Pythia~8 simulations of ${\rm D}^0$- and $\Lambda_c^+$-tagged jets, we find a pronounced, localized suppression of energy flow around the $\Lambda_c^+$ relative to the ${\rm D}^0$, followed by a sharp transition scaling as $\theta_0\propto1/p_{\rm T}^{\rm jet}$ with little tune dependence. The conventional jet-axis radial profile shows qualitatively different color-reconnection dependence, suggesting reduced sensitivity of HAEC to jet-axis effects. A beauty-sector study can distinguish a heavy-quark-mass origin from a local fragmentation-vertex origin.
Read the full abstract

High Energy Physics (Phenomenology)

Searching for new physics with contact-free transitions in muonic atoms

Noam Burger and Ben Ohayon

We present a feasibility study demonstrating how recent advances in quantum-sensing technologies can facilitate stringent comparisons between theoretical predictions and experimental measurements of contact-free transitions in muonic atoms. Such comparisons can probe previously unexplored regions of the parameter space governing spin-independent muon-proton interactions and disentangle the extraction of fundamental constants from searches for physics beyond the Standard Model.
Read the full abstract

High Energy Physics (Phenomenology)

Constraining Proton Spin at Small $x$ with Valence Quark Model

Yossathorn Tawabutr, Daniel Adamiak and Heikki Mäntysaari

Recently, a global analysis has been performed for longitudinal spin asymmetries in polarized deep inelastic scattering (DIS) processes, combining the polarized valence quark model with the large-$N_c \& N_f$ helicity evolution equations. With a three-fold reduction in the number of free parameters, the valence quark model results in a six-fold reduction of uncertainty for the resulting prediction of total parton spin inside the proton, when compared to previous analysis performed with traditional moderate-$x$ model inspired by Born approximation. The fit based on valence quark model predicts a positive gluon hPDF and negative $g_1$ structure function at small $x$. However, the resulting increase in the $\chi^2$-statistic of the fit warrants further examination into the physical uncertainty of the valence quark model, which is a work in progress. We also summarize other possibilities of future research directions towards the end of this article.
Read the full abstract

High Energy Physics (Phenomenology) · Cross-listed from astro-ph.CO

Probing multi-state dark matter via optical absorption lines in DESI spectra

Anoma Ganguly and Shadab Alam

We search for dark matter through absorption lines imprinted on the spectra of background sources whose sightlines pass through foreground dark matter halos. Such a line is a generic feature of multi-state dark matter models that couple to photons through higher-order electromagnetic moments. We focus on the minimal case of a two-state system with a magnetic dipole transition, in which the ground state absorbs a photon and makes a transition to the excited state. For transition energy $\Delta E \sim O \,(\text{eV})$, the line falls in the optical band, within reach of spectroscopic surveys such as DESI. Stacking 145,087 spectra of DESI Early Data Release objects paired with foreground GAMA galaxy groups, we find a stacked optical depth consistent with zero and place $2\sigma$ upper limits on the magnetic dipole transition cross-section. The limits are strongest at $\Delta E \sim$ 3-5 eV for a few MeV dark matter mass in the parameter space that is inaccessible to both cosmological (BBN+CMB) and direct detection experiments. We forecast that the full DESI and the next-generation spectroscopic surveys will tighten these limits by more than an order of magnitude, establishing spectroscopic stacking as a competitive probe of electromagnetically interacting multi-state dark matter.
Read the full abstract

High Energy Physics (Phenomenology)

Dark Matter Inelastic Scattering with Nuclei for Direct Detection

Shao-Feng Ge, Oleg Titov and Yakun Wang

We investigate the nuclear responses for the WIMP-nucleus scattering in the dark matter direct detection with particular emphasis on the inelastic channel for the $^{129}$Xe and $^{131}$Xe isotopes. Our generalization incorporates both the elastic and inelastic scattering channels. With multipole expansion of the effective operators, the angular momentum, parity and time-reversal selection rules can effectively determine the allowed transitions. Instead of the nuclear shell model, we use the state-of-the-art relativistic configuration-interaction density functional theory, which is more suitable for heavy nuclei such as xenon isotopes, to calculate the nuclear response functions. For certain interaction operators, the inelastic contribution can be comparable as its elastic counterpart and some can even dominate by up to three orders of magnitude. Additionally, the higher excited nuclear states can have comparable signal rate as the first excited states. We compare our results with the nuclear shell model calculation. The differences would have significant effects for interpreting the dark matter direct detection searches.
Read the full abstract

Monday 14 September

High Energy Physics (Phenomenology)

Testing Higgs-Coupled Minimal Dark Matter with Solar Neutrinos after the LZ High-Recoil Event

Mattia Di Mauro

The LUX-ZEPLIN (LZ) Collaboration has reported a nuclear-recoil candidate at $248$ keV, motivating interpretations in terms of endothermic dark matter (DM). We investigate this signal in Higgs-coupled minimal dark matter (HC-MDM), where the same electroweak interaction responsible for the terrestrial recoil also induces DM capture in the Sun and a potentially observable high-energy neutrino signal. We independently determine the mass splittings required to reproduce the LZ event and perform an improved calculation of Solar capture and post-capture evolution. Our treatment includes natural isotope mixtures, exact inelastic kinematics, nuclear form factors, finite-temperature nuclear motion near kinematic closure, orbital cooling through loop-induced elastic scattering, and an explicit capture–annihilation equilibrium test. The resulting Solar predictions are numerically stable and robust against the astrophysical and nuclear variations considered. For the two thermal benchmarks within the released IceCube DM mass grid, $3_M2_D$ and $5_M4_D$, the predicted annihilation rates exceed the mass-matched $W^+W^-$ IceCube response by factors of approximately $2.2\times10^3$ and $91$, placing both standard-halo solutions under strong tension within the $W^+W^-$ response mapping used here. For the heavier representations, whose masses lie above the published $10$ TeV IceCube grid, we construct a response-based extrapolation to higher masses. The $22$ TeV $7_M6_D$ benchmark remains in strong tension with IceCube even under our conservative response-loss extrapolation, while the $48$ TeV $9_M8_D$ benchmark also remains above the extrapolated response, although much closer to the sensitivity boundary. The $82$ TeV $11_M10_D$ benchmark is response dependent, whereas the $130$ TeV $13_M12_D$ benchmark remains below the extrapolated IceCube sensitivity.
Read the full abstract

High Energy Physics (Phenomenology) · Cross-listed from astro-ph.CO

FOSSIL: A future mission for CMB spectral distortion measurements

N. Aghanim, B. Maffei, J. Aumont et al. (+96 more)

We present FOSSIL, a proposed space mission which is designed to deliver unprecedented absolute spectroscopic measurements of the sky intensity over a broad frequency range (50GHz to 2THz) to accurately measure chemical-potential mu-type, Compton y-type, and Compton relativistic y-type CMB spectral distortions. FOSSIL will reach monopole sensitivities representing a gain of roughly three orders of magnitude over COBE/FIRAS. These capabilities will allow us to constrain primordial density fluctuations on scales k~(10 to 10^4)Mpc^-1, test inflationary models, probe dark matter annihilation/decay/interactions, constrain primordial black hole seed scenarios, and pin down feedback models in galaxy evolution and structure formation by measuring the cosmic thermal energy content. Furthermore, its 130 spectral channels will enable legacy astrophysics, including precise characterisation of the Cosmic Infrared Background, line intensity mapping during cosmic noon, and detailed Galactic dust mapping.
Read the full abstract

All authors N. Aghanim, B. Maffei, J. Aumont, A. Beelen, B. Borgo, E. Bozzo, J. Chluba, X. Coulon, S. Couturier, F. Cuttaia, B. Cyr, P. De Bernardis, C. De Jabrun, J.-J. Diaz-Garcia, D. Eckert, G. Fabbian, L. Ferrari, F. Finelli, T. Gascard, J. E. Gudmundsson, A. Kogut, G. Lagache, M. Loquet Le Gall, S. Martin, A. I. Silva Martins, A. Monfardini, C. O'Sullivan, L. Pagano, D. Paoletti, G. Pisano, M. Remazeilles, V. Reveret, J. A. Rubino-Martin, V. Sauvage, G. Savini, L. Spencer, A. Tartari, L. Terenzi, N. Trappe, D. Watts, B. Winter, E. Baker, E. S. Battistelli, R. Battye, J. L. Bernal, A. Besnard, F. R. Bouchet, M. Braglia, C. Burigana, M. Calvo, S. Caminade, M. Citran, D. Clements, W. Coulton, E. Courau, G. De Zotti, E. Di Valentino, H. Dole, G. Domenech, S. Evangelista, S. Farrens, M. Frailis, K. A. Glasscock, V. Hervier, E. Kovetz, H. Liu, T. Louis, F. Madec, A. S. Maniyar, C. J. A. P. Martins, S. Masi, L. Maurin, F. Moll, L. Morelli, S. K. Naess, A. Nicola, F. Pace, N. Ponthieu, V. Poulin, E. Prele, N. Sanchez, W. Qin, L. Rodriguez, D. Scott, F. Simon, J. Singal, T. Slatyer, E. M. Teixeira, L. Thiele, M. Tristram, T. Trombetti, L. Vacher, S. Vinzl, A. Zacchei, E. Allys, K. Aryan, J. M. Casas Gonzales, O. Lahav, C. Sidiropoulos

High Energy Physics (Phenomenology) · Cross-listed from astro-ph.HE

Right Energy, Wrong Profile: Why the 43 GeV Cluster Line Is Unlikely to Be Dark Matter

Stefano Profumo

A narrow gamma-ray line would be a distinctive signature of dark matter, but its interpretation depends as much on its spatial distribution as on its energy. We reanalyze the reported 43 GeV feature in Fermi-LAT observations of Virgo, Fornax, and Ophiuchus. The excess is reproduced in the same public data and survives event-type partitions, a test using data withheld from the original selection, and detector-coordinate permutation tests. Realistic hadronic and inverse-Compton emission is too broad to explain it. A spatial–spectral likelihood analysis restricted to Good Time Intervals and including diffuse backgrounds and catalogued sources finds a broad line-like component. Uniform surface brightness and substructure-enhanced annihilation are preferred, whereas smooth NFW annihilation and a central point source are unlikely explanations. An independent annular analysis agrees: the events associated with the excess extend through much of the virial region. Calibration over 20–70 GeV and five morphologies gives a conditional global significance of approximately $2.7\sigma$, peaking at 44.5 GeV for uniform brightness. This result is conditional on the preselected three-cluster sample. The broad morphology is the main obstacle to a dark-matter interpretation. Such an interpretation would require photons to be a leading annihilation channel, annihilation to remain efficient in cold subhalos, and subhalos to supply nearly all the cluster luminosity. Yet a boost consistent with $\Lambda$CDM drives the required two-photon cross section into the range most tightly constrained by Galactic-halo line limits. The most likely explanation is a chance fluctuation amplified by analysis and target-selection effects, possibly compounded by residual Galactic diffuse or unresolved-source mismodeling; if celestial, its morphology makes a simple dark-matter interpretation unlikely.
Read the full abstract

High Energy Physics (Phenomenology)

Topological Integer-Winding Dark Matter with a Dark Higgs Triplet: Stability from $\pi_2(\mathrm{SU}(3)/\mathrm{SO}(3)) = \mathbb{Z}$

Ahmed Ali

We propose a dark matter model in which the symmetry-breaking pattern SU(3)_dark -> SO(3)_dark x Z_2 produces absolutely stable point-like topological defects classified by pi_2(SU(3)/[SO(3) x Z_2]) = Z. The lightest neutral member chi^0 of the resulting dark octet, with mass M(chi^0) = 165.67 GeV, couples to Standard Model fields only through a kinetic-mixing portal (g_f = 10^-3) and gravity. A dark Higgs triplet Delta_dark with vacuum expectation value v_Delta = 17 GeV and Yukawa coupling y_chi = 0.10 generates a tree-level splitting Delta M(chi^+ - chi^0) = 1.70 GeV, opening the decay chi^+ -> chi^0 + phi^+ and ensuring that chi^0 is the unique stable relic. An extended Gell-Mann-Okubo mass operator incorporating the quantum number darkicity T_dark predicts three scale-independent mass ratios, r_21 = M(chi^++)/M(chi^0) = 1.089 +/- 0.005, r_31 = M(Sigma^0_dark)/M(chi^0) = 1.163 +/- 0.006, and r_41 = M(Lambda_dark)/M(chi^0) = 1.260 +/- 0.008, falsifiable at FCC-ee. Eight coupled Boltzmann equations with co-annihilation yield Omega_DM h^2 = 0.120 at M_0 = 208.67 GeV. Self-interaction cross-sections satisfy all astrophysical bounds from dwarf galaxies to the Bullet Cluster. The model predicts a stochastic gravitational-wave background at f_* = 1.65 mHz (LISA, SNR = 8.5) and dark acoustic oscillations at r_DAO = 2.3 +/- 0.4 Mpc (SKA).
Read the full abstract

High Energy Physics (Phenomenology)

Top-quark pair production sensitivity to heavy new physics at the FCC-ee

Jacopo De Piccoli, Gauthier Durieux, Sergio Sánchez Cruz et al. (+1 more)

We study the sensitivity of top-quark pair production at the FCC-ee to heavy new physics, parametrised in the Standard Model effective field theory, using discriminants based on matrix elements. The analysis includes detector reconstruction effects, obtained with a fast simulation of the IDEA detector concept, and jet flavour tagging. We consider dimension-six operators that modify the electroweak couplings of the top quark or generate four-fermion interactions, at leading order and in diagrams with two resonant top quarks. The full six-body kinematic information is employed to maximise the discrimination power against the Standard Model. Two bins per dimension in the space of 12 discriminants, one per operator considered, provide a simple and robust methodology to set nearly optimal multidimensional constraints. Bounds on the new physics scale can reach values up to 30 TeV in a single-operator fit and up to 5 TeV in a global multi-operator fit. A combination with High-Luminosity LHC prospects on top-quark operators shows complementary sensitivities which help lift approximate degeneracies.
Read the full abstract

All authors Jacopo De Piccoli, Gauthier Durieux, Sergio Sánchez Cruz, Michele Selvaggi

High Energy Physics (Phenomenology) · Cross-listed from astro-ph.HE

Neutron Star Merger Universality Relations for a Quark–Hadron Crossover Equation of State

Wei Sun, Grant J. Mathews and Atul Kedia

A crossover transition from hadronic to quark matter during the merger of neutron stars can lead to interesting observational consequences in the emergent gravitational radiation. In particular, the increased pressure in the crossover density region ($2-5$ times the nuclear saturation density) can lead to an extended duration of high-frequency ($\sim 2-3.5$ kHz) gravitational wave emission during the post-merger epoch. We study the universality relations for a variety of equations of state with and without a crossover transition to a quark mater based upon the QHC19 and QHC21 EoSs. We find that the long-duration post-merger gravitational-wave emission is more pronounced in the QHC21 EoS. We then consider universality relations among various observable quantities that have been identified in simulations with hadronic equations of state. We show that there are deviations from the universality relations for some quantities that may ultimately provide an observational signal that such a transition has occurred.
Read the full abstract

High Energy Physics (Phenomenology) · Cross-listed from nucl-th

Comprehensive study of $\Upsilon$($n$S) production in Oxygen+Oxygen collisions at LHC

Sabin Thapa, Biaogang Wu, Ramona Vogt et al. (+1 more)

We study bottomonium $\Upsilon$($n$S) production in ${\rm O}+{\rm O}$ collisions at $\sqrt{s_{NN}}=5.36$~TeV, including both cold nuclear-matter (CNM) effects and final-state interactions in a short-lived quark-gluon plasma. The CNM baseline is calculated using the EPPS21 nuclear parton distribution functions together with coherent energy loss and transverse momentum broadening. Hot-medium effects are evaluated with two transport approaches coupled to the same centrality-resolved 3+1D aHydroQP background: the QTRAJ-NLO open-quantum-system calculation, implemented with the QTraj code, and the TAMU-NP semiclassical rates, including primordial suppression and regeneration. The CNM effects give a moderate, state-independent suppression, dominated by the nPDF modification. The energy loss and transverse momentum broadening contribution remains at the few-percent level. Both transport approaches predict a sequential suppression pattern, $R_{AA}^{\Upsilon(1\rm{S})}>R_{AA}^{\Upsilon(2\rm{S})}>R_{AA}^{\Upsilon(3\rm{S})}$, with the strongest suppression around midrapidity in central collisions. The suppression of the ground state is similar in the two approaches but differs for the excited states. Since the CNM factor is common to all states, double ratios provide a direct measure of the relative hot-medium suppression. Our results support the conclusion that ${\rm O}+{\rm O}$ collisions at the LHC can produce a short-lived QGP capable of modifying bottomonium yields.
Read the full abstract

All authors Sabin Thapa, Biaogang Wu, Ramona Vogt, Ralf Rapp

High Energy Physics (Phenomenology) · Cross-listed from hep-ex

Probabilistic, Structure-Intrinsic Clustering with an Hierarchical Embedding (PSICHE) in Time and Space Applied In Particle Physics Jet Reconstruction

Margaret Lazarovits and Christopher Rogan

Jet reconstruction is an active and open area of particle physics research, with questions related to jet size, multiplicity, substructure, and experimental performance in the presence of pileup and noise. Analogous challenges are ubiquitous throughout other applications of unsupervised learning in the context of clustering and association. This paper introduces a new algorithm for clustering in the context of jet reconstruction: Probabilistic, Structure-Intrinsic Clustering with an Hierarchical Embedding (PSICHE). PSICHE addresses several challenges and shortcomings of existing jet clustering methods with novel features, including but not limited to: (i) dynamically-learned and variable jet (cluster) sizes, (ii) unsupervised, multi-scale learning of emergent features, like jet substructure and multiplicity, (iii) clustering in space and time, and (iv) incorporation of domain-specific experimental uncertainties. All of these properties are achieved in a self-consistent, probabilistic framework that is computationally tractable. Furthermore, demonstrations of these features are presented for a range of jet clustering examples in LHC scenarios for various physics phenomena, clustering inputs, pileup conditions, and detector performance parameters.
Read the full abstract

High Energy Physics (Phenomenology)

Enhanced Standard Model bound on charm CP violation from QCD penguins

Ali Mohamed and Maria Laura Piscopo

We investigate the impact of QCD penguin operators on direct CP violation in singly Cabibbo-suppressed $D^0$ decays within the framework of light-cone sum rules (LCSR) using pion and kaon light-cone distribution amplitudes. We determine, for the first time, the hadronic matrix elements of the QCD penguin operators for $D^0\to K^+K^-$ and $D^0\to\pi^+\pi^-$ at leading order in $\alpha_s$, employing a three-point correlation function with an artificial momentum to avoid unphysical parasitic cuts. We also compute the matrix elements of the current-current operators using the same framework and compare them with previous LCSR results. We find that the scalar penguin operators $Q_5$ and $Q_6$ can have substantially enhanced matrix elements. We identify two sources of enhancement: quark-condensate contributions, which arise already at tree level and are therefore enhanced by a relative factor of $16 \pi^2$ compared to the remaining, loop-induced terms in the sum rule; and an annihilation-type contribution from the $\bar u u$ component of these operators, which enters already through twist-three light-cone distribution amplitudes and is of comparable magnitude. While the impact of QCD penguin operators on the branching ratios is negligible, they can enhance the magnitude of the “penguin-to-tree” amplitude ratios relevant for direct CP violation. The relevant strong phases, however, remain largely unconstrained within the accuracy of our framework. Assuming maximal relative strong phases, we find that the corresponding upper bound on the Standard Model contribution to charm CP violation can be enhanced compared to estimates based on the current-current operators alone, reducing the gap with the experimental measurement.
Read the full abstract

High Energy Physics (Phenomenology) · Cross-listed from nucl-th

Obtaining tensor-polarized nuclei with spin $S\ge1$ via spin filtering upon nuclear beam transmission through an unpolarized target (spin dichroism effect)

Sergey Anishchenko, Vladimir Baryshevsky and Alexandra Gurinovich

Upon transmission through an unpolarized target initially unpolarized nuclei with spin $S\ge1$ acquire tensor polarization due to spin dichroism effect. For nuclei passing several nuclear lengths in the target, the acquired component $p_{zz}$ can reach substantial values of ~0.2-0.8. The beam obtained in this way can be effectively used to study reactions with tensor-polarized nuclei.
Read the full abstract

High Energy Physics (Phenomenology) · Cross-listed from astro-ph.CO

Peering Beyond the Veil of Last Scattering: A View of the Universe with CMB Spectral Distortions

Bryce Cyr, Nabila Aghanim, Ethan Baker et al. (+37 more)

The frequency spectrum of the cosmic microwave background is the most precise blackbody ever measured in nature, with deviations constrained at the level of almost one part per million from the COBE satellite. Nevertheless, departures away from a perfect blackbody are present in standard $\Lambda$CDM cosmology, lurking just beneath the surface of our current observational bounds. These spectral distortions provide invaluable information on our thermal history in both the post- and pre-recombination epochs, allowing us to peer beyond last scattering and into the primordial Universe. Here, we present an overview of the underlying physics responsible for generating CMB spectral distortions at all epochs. As an illustration of this rich physics, we review a comprehensive set of mechanisms capable of generating distortions both within and beyond the standard $\Lambda$CDM paradigm. We also discuss the information that can be gleaned by going beyond the monopole (sky-averaged) spectrum and exploiting the spatial information present in anisotropic spectral distortions. To supplement our discussion of the diverse science of spectral distortions, we provide an overview of the upcoming and proposed experimental landscape. We highlight that the combination of the TMS, COSMO, and BISOU experiments will provide the first discovery of a monopole $y$-type distortion within the coming decade. From space, the proposed FOSSIL experiment is forecasted to improve upon the original COBE/FIRAS measurement by roughly three orders of magnitude in sensitivity, bringing with it the detection of the $\Lambda$CDM $\mu$-type distortion sourced by the dissipation of small scale acoustic modes in the pre-recombination plasma. With transformational measurements on the horizon, CMB spectral distortions offer a uniquely sensitive probe of the thermal history of the Universe at redshifts $z \lesssim 2 \times 10^6$.
Read the full abstract

All authors Bryce Cyr, Nabila Aghanim, Ethan Baker, Elia Stefano Battistelli, Richard Battye, José Luis Bernal, Jens Chluba, Xavier Coulon, William Coulton, Paolo de Bernardis, Eleonora Di Valentino, Guillem Domènech, Sara Evangelista, Giulio Fabbian, Fabio Finelli, J. Colin Hill, Rishi Khatri, Alan Kogut, Guilaine Lagache, Hongwan Liu, Bruno Maffei, Fereshteh Majidi, Abhishek S. Maniyar, C. J. A. P. Martins, Silvia Masi, Jeff McMahon, Daniela Paoletti, Vivian Poulin, Wenzer Qin, Mathieu Remazeilles, José Alberto Rubiño-Martín, Alina Sabyr, Mayuri Sathyanarayana Rao, Carlos Sierra, Jack Singal, Tracy R. Slatyer, Elsa M. Teixeira, Leander Thiele, Léo Vacher, Duncan Watts

High Energy Physics (Phenomenology)

Composite dark matter at the LHC

Alan S. Cornell, Louie Corpe, Aldo Deandrea et al. (+3 more)

We investigate a composite-inspired model in which a scalar dark matter candidate couples to third-generation quarks through a non-minimal set of coloured vector-like fermions, as motivated by partial compositeness. The simultaneous presence of several mediator states leads to a richer phenomenology than conventional single-mediator descriptions, and we confront the framework with the observed relic abundance, direct-detection and indirect-detection constraints, as well as data from the Large Hadron Collider. At colliders, we compare the sensitivity of dedicated new-physics searches with that of unfolded measurements of Standard Model processes, and we assess the impact of higher-order corrections on the different production mechanisms. We find that dedicated searches generally provide the strongest collider exclusions, while unfolded measurements offer complementary sensitivity. Direct detection becomes increasingly powerful as the interaction strength grows and can become the dominant constraint. This broader complementarity arises because collider data directly test the production and decay of the coloured mediators, whereas cosmological and astroparticle observables constrain the interactions governing dark-matter abundance, scattering and annihilation. Although present constraints significantly restrict the model, viable regions compatible with the observed dark-matter abundance remain.
Read the full abstract

All authors Alan S. Cornell, Louie Corpe, Aldo Deandrea, Benjamin Fuks, Taylor Murphy, Clarisse Prat

High Energy Physics (Phenomenology) · Cross-listed from hep-th

Making the Great Desert Bloom

Jacques Distler and Andreas Karch

The absence of new physics beyond neutrino masses between the weak scale and the Planck scale is referred to as the great desert. It is often seen as a nightmare scenario for particle physics. Here we argue, by contrast, that the great desert assumption in fact has dramatic implications: it predicts that the Standard Model has a semi-classical AdS$_4$ vacuum with CFT$_3$ dual and, under reasonable assumptions, must be accompanied by at least one extra dimension significantly larger than Planck length. We also present one plausible candidate CFT$_3$ to be “the" dual to the Standard Model.
Read the full abstract