Thu·Jul 20, 2023Thursday·July 20, 2023

1. 01*

   Orbital Angular Momentum at Small $x$

   Brandon Manley🇺🇸

   We revisit the problem of the small Bjorken-$x$ asymptotics of the quark and gluon orbital angular momentum (OAM) distributions in the proton utilizing the revised formalism for small-$x$ helicity evolution derived recently in a paper by Cougoulic, Kovchegov, Tarasov, and Tawabutr. We relate the quark and gluon OAM distributions at small $x$ to the polarized dipole amplitudes and their (first) impact-parameter moments. To obtain the $x$-dependence of the OAM distributions, we derive novel small-$x$ evolution equations for the impact-parameter moments of the polarized dipole amplitudes in the double-logarithmic approximation (summing powers of ${\alpha }_s{\ln }^2(1/x)$ with ${\alpha }_s$ the strong coupling constant). We solve these evolution equations numerically and extract the large-$N_c$, small-$x$ asymptotics of the quark and gluon OAM distributions, which we determine to be \[ L_{q+\bar{q}}(x, Q^2) \sim L_{G}(x,Q^2) \sim \Delta \Sigma(x, Q^2) \sim \Delta G(x,Q^2) \sim \left(\frac{1}{x}\right)^{3.66 \, \sqrt{\frac{\alpha_s N_c}{2\pi}}},\] in agreement with an earlier work by Boussarie, Hatta, and Yuan within the precision of our numerical evaluation (here $N_c$ is the number of quark colors). We also investigate the ratios of the quark and gluon OAM distributions to their helicity distribution counterparts in the small-$x$ region.

   hep-phnucl-th1 citation
2. 02*

   Gauge $SU(2{)}_f$ flavour transfers

   Luc Darmé🇫🇷 · Aldo Deandrea🇫🇷 · Farvah Mahmoudi🇫🇷

   We introduce the idea of flavour transfer from a non-abelian horizontal $SU(2{)}_f$ flavour gauge group embedded in the Standard Model flavour structure. The new flavour vector bosons, in the mass range from the tens of GeV to multi-TeV do not induce large flavour-changing currents and meson oscillations, which usually provide the dominant constraints on this type of structure. Instead, the dominant constraints arise from "flavour-transfer" operators that we will study in details. Several explicit models are presented and their prospects are thoroughly explored, including their phenomenology in the lepton and quark sectors at colliders and lower energy experiments. We finally perform a complete numerical fit in one such scenario, showing that LHC-based lepton-flavour violating searches are competitive with intensity frontier observables.

   hep-phJHEP(2024)·18 citations
3. 03*

   Multiscale evolution of heavy flavor in the QGP

   G. Vujanovic · A. Angerami · R. Arora · S. A. Bass · S. Cao · Y. Chen · T. Dai · L. Du · R. Ehlers · H. Elfner · W. Fan · R. J. Fries and 43 other authors

   Shower development dynamics for a jet traveling through the quark-gluon plasma (QGP) is a multiscale process, where the heavy flavor mass is an important scale. During the high virtuality portion of the jet evolution in the QGP, emission of gluons from a heavy flavor is modified owing to heavy quark mass. Medium-induced radiation of heavy flavor is sensitive to microscopic processes (e.g. diffusion), whose virtuality dependence is phenomenologically explored in this study. In the lower virtuality part of shower evolution, i.e. when the mass is comparable to the virtuality of the parton, scattering and radiation processes of heavy quarks differ from light quarks. The effects of these mechanisms on shower development in heavy flavor tagged showers in the QGP is explored here. Furthermore, this multiscale study examines dynamical pair production of heavy flavor (via virtual gluon splittings) and their subsequent evolution in the QGP, which is not possible otherwise. A realistic event-by-event simulation is performed using the JETSCAPE framework. Energy-momentum exchange with the medium proceeds using a weak coupling recoil approach. Using leading hadron and open heavy flavor observables, differences in heavy versus light quark energy-loss mechanisms are explored, while the importance of heavy flavor pair production is highlighted along with future directions to study.

   hep-phnucl-exnucl-thPoS(2024)·0 citations
4. 04*

   A new metric improving Bayesian calibration of a multistage approach studying hadron and inclusive jet suppression

   W. Fan🇺🇸 · G. Vujanovic🇨🇦 · S. A. Bass🇺🇸 · A. Angerami🇺🇸 · R. Arora🇺🇸 · S. Cao🇨🇳 · Y. Chen🇺🇸 · T. Dai🇺🇸 · L. Du🇨🇦 · R. Ehlers🇺🇸 · H. Elfner🇩🇪 · R. J. Fries🇺🇸 and 43 other authors

   We study parton energy-momentum exchange with the quark gluon plasma (QGP) within a multistage approach composed of in-medium DGLAP evolution at high virtuality, and (linearized) Boltzmann Transport formalism at lower virtuality. This multistage simulation is then calibrated in comparison with high $p_T$ charged hadrons, D-mesons, and the inclusive jet nuclear modification factors, using Bayesian model-to-data comparison, to extract the virtuality-dependent transverse momentum broadening transport coefficient $\hat{q}$. To facilitate this undertaking, we develop a quantitative metric for validating the Bayesian workflow, which is used to analyze the sensitivity of various model parameters to individual observables. The usefulness of this new metric in improving Bayesian model emulation is shown to be highly beneficial for future such analyses.

   hep-phnucl-exnucl-thPRC(2024)·17 citations
5. 05*

   Heavy quark diffusion coefficients in magnetized quark-gluon plasma

   Aritra Bandyopadhyay🇩🇪

   We evaluate the heavy quark momentum diffusion coefficients in a hot magnetized medium for the most general scenario of any arbitrary values of the external magnetic field. We choose to work with the systematic way of incorporating the effect of the magnetic field, by using the effective gluon and quark propagators, generalized for a hot and magnetized medium. To get gauge independent analytic form factors valid through all Landau levels, we apply the Hard Thermal Loop (HTL) technique for the resummed effective gluon propagator. The derived effective HTL gluon propagator and the generalized version of Schwinger quark propagator subsequently allow us to analytically evaluate the longitudinal and transverse momentum diffusion coefficients for charm and bottom quarks beyond the static limit. Within the static limit we also explore another way of incorporating the effect of the magnetic field, i.e. through the magnetized medium modified Debye mass and compare the results to justify the need for structural changes.

   hep-phPRD(2024)·12 citations
6. 06*

   Electromagnetic Debye mass within Gribov-Zwanziger action

   Aritra Bandyopadhyay🇩🇪

   In the present study we have investigated the electromagnetic Debye mass by computing the static limit of the temporal component of the one-loop photon polarization tensor involving effective quarks in the loop. These effective quarks have been considered within the Gribov-Zwanziger action, thereby incorporating the necessary non-perturbative effects. As an academic exercise, we have also shown one of the applications of this Gribov modified Debye mass by using it to evaluate the real and imaginary parts of the heavy quark potential in a QED system. This computation of the electromagnetic Debye mass and the corresponding estimations of the heavy quark potential can be seen as stepping stones in the direction of further practical QCD calculations in the non perturbative domain.

   hep-phJ.Phys.G(2024)·11 citations
7. 07*

   Probing new physics through entanglement in diboson production

   Rafael Aoude🇧🇪 · Eric Madge🇮🇱 · Fabio Maltoni🇧🇪 · Luca Mantani🇬🇧

   Pair production of heavy vector bosons is a key process at colliders: it allows to test our understanding of the Standard Model and to explore the existence of new physics through precision measurements of production rates and differential distributions. New physics effects can be subtle and often require observables specifically designed for their detection. In this study, we focus on quantum information observables that characterise the spin states of the final diboson system. We analyse concurrence bounds, purity, and Bell inequalities for a bipartite qutrit system representing two massive gauge bosons. Our findings show that quantum spin observables can serve as complementary probes for heavy new physics as parametrised by higher dimensional operators in the Standard Model effective field theory. In particular, we find that these observables offer increased sensitivity to operators whose contributions do not interfere with the Standard Model amplitudes at the level of differential cross sections.

   hep-phhep-thJHEP(2023)·106 citations
8. 08*

   Probing for chiral $Z^{\prime }$ gauge boson through scattering measurement experiments

   Kento Asai🇯🇵 · Arindam Das🇯🇵 · Jinmian Li🇨🇳 · Takaaki Nomura🇨🇳 · Osamu Seto🇯🇵

   Motivated by the observation of tiny neutrino mass can not be explained within the framework of Standard Model (SM), we consider extra gauge extended scenarios in which tiny neutrino masses are generated through seesaw mechanism. These scenarios are equipped with beyond the standard model (BSM) neutral gauge boson called $Z^{\prime }$ in the general $U(1{)}_X$ symmetry which is a linear combination of $U(1{)}_Y$ and $U(1{)}_{B-L}$. In this case, left and right handed fermions interact differently with the $Z^{\prime }$. The $Z^{\prime }$ gives rise to different processes involving neutrino-nucleon, neutrino-electron, electron-nucleus and electron-muon scattering processes. By comparing with proton, electron beam-dump experiments data, recast data from searches for the long-lived and dark photon at BaBaR, LHCb and CMS experiments, the electron and muon $g-2$ data, and the data of the dilepton and dijet searches at the LEP experiment, we derive bounds on the gauge coupling and the corresponding gauge boson mass for different $U(1{)}_X$ charges and evaluate the prospective limits from the future beam-dump scenarios at DUNE, FASER(2) and ILC. We conclude that large parameter regions could be probed by scattering, beam-dump and collider experiments in future.

   hep-phastro-ph.HEhep-exPRD(2024)·26 citations
9. 09*

   Spatial imaging of proton via leading-twist non-skewed GPDs with basis light-front quantization

   Satvir Kaur🇨🇳 · Siqi Xu🇨🇳 · Chandan Mondal🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸

   The internal image of the proton is unveiled by examining the generalized parton distributions (GPDs) at zero skewness, within the basis light-front quantized environment. Several distributions emerge when a quark is sampled with different currents depending upon the helicity arrangements of the active quark and the proton target. We investigate six of the eight leading-twist proton GPDs of the valence quarks, the helicity conserving distributions $(H,E,\tilde{H})$ and the helicity non-conserving $(H_T,E_T,{\tilde{H}}_T)$ distributions at skewness set to zero ($\zeta =0$). We consider purely transverse momentum transfer and, hence, obtain results describe only the proton's two-dimensional structure in the transverse plane. We present the Mellin moments of these distribution functions, where the first moment produces a form factor and the second Mellin moments help extract the information on partonic contributions to the hadronic angular momentum. We compare our results for the Mellin moments with those from lattice QCD and other approaches where available. We also present the GPDs in transverse position space.

   hep-phhep-thnucl-thPRD(2024)·37 citations
10. 10*

    Inverse problem in femtoscopic correlation functions: The $T_{cc}(3875{)}^{+}$ state

    M. Albaladejo🇪🇸 · A. Feijoo🇪🇸 · I. Vidaña🇮🇹 · J. Nieves🇪🇸 · E. Oset🇪🇸

    We study here the inverse problem of starting from the femtoscopic correlation functions of related channels and analyze them with an efficient tool to extract the maximum information possible on the interaction of the components of these channels, and the existence of possible bound states tied to this interaction. The method is flexible enough to accommodate non-molecular components and the effect of missing channels relevant for the interaction. We apply the method to realistic correlation functions for the $D^{\ast +}{D}^0$ and $D^{\ast 0}{D}^{+}$ channels derived consistently from the properties of the $T_{cc}(3875{)}^{+}$ and find that we can extract the existence of a bound state, its nature as a molecular state of the $D^{\ast +}{D}^0$ and $D^{\ast 0}{D}^{+}$ channels, the probabilities of each channel, as well as scattering lengths and effective ranges for the channels, together with the size of the source function, all of them with a relatively good precision.

    hep-phhep-exnucl-exnucl-thEPJA(2025)·31 citations
11. 11*

    Predictions of the ratio and asymmetry probes of the invisible $Z$-boson decay

    Kadir Saygin🇹🇷

    Higher-order predictions through the combined accuracy including next-to-leading order (NLO) electroweak (EW) and next-to-NLO (NNLO) quantum chromodynamics (QCD) corrections in underlying perturbation theories are presented thoroughly for the invisible decay of the $Z$ boson into neutrino pair relative to its decay into charged-lepton pair (leptonic decay). The combined NNLO QCD+NLO EW predictions are achieved based on the fully-differential calculations of cross sections of both the invisible and leptonic processes in proton-proton ($pp$) collisions at 13 TeV center-of-mass energy. Differential distributions of cross-section ratios of the invisible process to the leptonic process are presented as a function of the transverse momentum of the $Z$ boson $p_{\mathrm{T}}^Z$. For the first time, the predictions for differential distributions of cross-section asymmetries between the invisible process and the leptonic process are presented in bins of the $p_{\mathrm{T}}^Z$. The cross-section ratio and asymmetry distributions, which are referred to as the invisible probes, are considered to be important for controlling the invisible process by the leptonic process of the $Z$ boson and probing deviation from the Standard Model (SM) for new-physics searches. The predictions are extensively presented beyond the $Z$-boson mass resonance region to assess the potential of the invisible ratio and asymmetry probes for new-phenomena searches in high-invariant mass region of the lepton-pair final states. Various tests with threshold requirements of transverse momenta of neutrino pair and leptons are performed to assess the impact on the combined predictions. The invisible ratio and asymmetry probes are proposed to be important probes for indirect searches of new-physics scenarios.

    hep-phPhys.Scripta(2023)·1 citation
12. 12*

    Miniclusters from axion string simulations

    Giovanni Pierobon🇦🇺 · Javier Redondo🇪🇸 · Ken'ichi Saikawa🇯🇵 · Alejandro Vaquero🇪🇸 · Guy D. Moore🇩🇪

    The properties of axion miniclusters and of the voids between them can have very strong implications for the discovery of axions and the dark matter of the Universe. These properties can be strongly affected by axion dynamics in the early Universe, such as the axion string network and the non-linear dynamics around the QCD phase transition. Recently, improvements in numerical simulation techniques have allowed us to calculate the dark matter axion field from axion strings and QCD effects using different methods: directly with low-tension strings but high resolution, directly with effective high-tension strings, or indirectly by extrapolating an attractor solution. In this work, we study the properties of miniclusters in the different approaches used in the literature. We find that, while there are substantial differences in the mass distribution and internal density profiles, globally there is a similar energy distribution between minicluster halos and voids.

    hep-phastro-ph.COJCAP(2026)·25 citations
13. 13*

    FCNCs, Proton Stability, $g_{\mu }-2$ Discrepancy, Neutralino cold Dark Matter in Flipped $SU(5)\times U(1{)}_{\chi }$ from $F$ Theory with $A_4$ Symmetry

    Gayatri Ghosh🇮🇳

    We predict the low energy signatures of a Flipped $SU(5)\times U(1{)}_{\chi }$ effective local model , constructed within the framework of F$-$theory based on $A_4$ symmetry. The Flipped SU(5) model from F Theory in the field of particle physics is prominent due to its ability to construct realistic four$-$dimensional theories from higher$-$dimensional compactifications which necessitates a unified description of the fundamental forces and particles of nature, used for exploring various extensions of the Standard Model. We study Flipped $SU(5)\times U(1{)}_{\chi }$ Grand Unified Theories (GUTs) with $A_4$ modular symmetry. In our model due to different modular weights assignments, the fermion mass hierarchy exists with different weighton fields. The constraints on the Dirac neutrino Yukawa matrix allows a good tuning to quark and charged lepton masses and mixings for each weighton field, with the neutrino masses and lepton mixing well determined by the type I seesaw mechanism which occurs at the expense of some tuning which manifests itself in charged lepton flavour violating decays which we explore here. The minimal Flipped $SU(5$) model is supplemented with an extra right$-$handed type and its complex conjugate electron state, $E_c+\overline{E_c}$, as well as neutral singlet fields. The $E_c+\overline{E_c}$ pair gets masses of the order of TeV which solves the $g_{\mu }-2$ discrepancy. The predictions of the model for charged lepton flavour violation decay rate and proton decay could be tested in near future experiments. Also we detect in our model the existence of neutralino, its charge mass and spin via direct and indirect detection.

    hep-phIndian J.Phys.(2024)·2 citations
14. 14*

    Quantum simulation of jet evolution in a medium

    Wenyang Qian🇪🇸

    Jets provide one of the primary probes of the quark-gluon plasma produced in ultrarelativistic heavy ion collisions and the cold nuclear matter explored in deep inelastic scattering experiments. However, despite important developments in the last years, a description of the real-time evolution of QCD jets inside a medium is still far from complete. In our previous work, we have explored quantum technologies as a promising alternative theoretical laboratory to simulate jet evolution in QCD matter, to overcome inherent technical difficulties in present calculations. Here, we extend our previous investigation from the single particle to the multiple particle Fock spaces, taking into account gluon production. Based on the light-front Hamiltonian formalism, we construct a digital quantum circuit that tracks the evolution of a multi-particle jet probe in the presence of a stochastic color background. Using the quantum simulation algorithm, we show the medium-induced modification to the jet evolution in both the momentum broadening and gluon production.

    hep-phquant-phPoS(2024)·1 citation
15. 15*

    Taming a leading theoretical uncertainty in HH measurements via accurate simulations for bbH production

    Stefano Manzoni🇨🇭 · Elena Mazzeo🇮🇹 · Javier Mazzitelli🇨🇭 · Marius Wiesemann🇩🇪 · Marco Zaro🇮🇹

    We present a new simulation for Higgs boson production in association with bottom quarks ($b\bar{b}H$) at next-to-leading order (NLO) accuracy matched to parton showers in hadronic collisions. Both contributions, the standard one proportional to the bottom-quark Yukawa coupling and the loop-induced one proportional to the top-quark Yukawa coupling from the gluon-fusion process, are taken into account in a scheme with massive bottom quarks. Therefore, we provide the full simulation of the $b\bar{b}H$ final state in the Standard Model, which constitutes also a crucial background to measurements for Higgs-boson pair ($HH$) production at the Large Hadron Collider when at least one of the Higgs bosons decays to bottom quarks. So far, the modeling of the $b\bar{b}H$ final state induced one of the dominant theoretical uncertainties to $HH$ measurements, as the gluon-fusion component was described only at the leading order (LO) with uncertainties of $\mathcal{O}(100\%)$. Including NLO corrections in its simulation allows us to reduce the scale dependence to $\mathcal{O}(50\%)$ so that it becomes subdominant with respect to other systematic uncertainties. As a case study, we provide an in-depth analysis of the $b\bar{b}H$ background to $HH$ measurements with realistic selection cuts in the $2b2\gamma$ channel. We also compare our novel simulation with the currently-employed ones, discussing possible issues and shortcomings of a scheme with massless bottom quarks. Finally, we propagate the effect of the new $b\bar{b}H$ simulation to $HH$ searches in the $2b2\gamma$ and $2b2\tau$ final states, and we find an improvement of up to 10% (20%) on the current (HL-LHC) limits on the $HH$ cross section.

    hep-phhep-exJHEP(2023)·27 citations
16. 16*

    Split NMSSM from dimensional reduction of a $10D$, $\mathcal{N}=1$ $E_8$ over $SU(3)/U(1)\times U(1)\times Z_3$

    Gregory Patellis🇵🇹 · Werner Porod🇩🇪 · George Zoupanos🇬🇷

    We examine an extension of the Standard Model which results from a $10D$, $\mathcal{N}=1$, $E_8$ gauge theory. The theory is dimensionally reduced over a $M_4\times B_0/{\mathbf{Z}}_3$ space, where $B_0$ is the nearly-Kähler manifold $SU(3)/U(1)\times U(1)$ and ${\mathbf{Z}}_3$ is a freely acting discrete group on $B_0$ that triggers a Wilson flux breaking, leading to an $\mathcal{N}=1$, $SU(3{)}^3\times U(1{)}^2$ effective theory in $4D$. At lower energies we are left with the Split NMSSM. Its 2-loop analysis yields third generation quark and light Higgs masses within the experimental limits and predicts a neutralino LSP mass $<800$ GeV.

    hep-phhep-thJHEP(2024)·14 citations
17. 17*

    Accidentally light scalars from large representations

    Felix Brümmer🇫🇷 · Giacomo Ferrante🇫🇷 · Michele Frigerio🇫🇷 · Thomas Hambye🇧🇪

    In models with spontaneous symmetry breaking by scalar fields in large group representations, we observe that some of the scalar masses can be loop-suppressed with respect to the naive expectation from symmetry selection rules. We present minimal models -- the $\mathrm{SU}(2)$ five-plet and $\mathrm{SU}(3)$ ten-plet -- with such accidentally light scalars, featuring compact tree-level flat directions lifted by radiative corrections. We sketch some potential applications, from stable relics and slow roll in cosmology, to hierarchy and fine-tuning problems in particle physics.

    hep-phhep-thJHEP(2024)·5 citations
18. 18*

    Gauge invariant spectral analysis of quark hadronization dynamics

    Alberto Accardi🇺🇸 · Caroline S. R. Costa🇺🇸 · Andrea Signori🇮🇹

    We study the Dirac decomposition of the gauge invariant quark propagator, whose imaginary part describes the hadronization of a quark as this interacts with the vacuum, and relate each of its coefficients to a specific sum rule for the chiral-odd and chiral-even quark spectral functions. Working at first in light-like axial gauge, we obtain a new sum rule for the spectral function associated to the gauge fixing vector, and show that its second moment is in fact equal to zero. Then, we demonstrate that the first moment of the chiral-odd quark spectral function is equal in any gauge to the so-called inclusive jet mass, which is related to the mass of the particles produced in the hadronization of a quark. Finally, we present a gauge-dependent formula that connects the second moment of the chiral-even quark spectral function to invariant mass generation and final state rescattering in the hadronization of a quark.

    hep-phhep-exnucl-thPRD(2023)·4 citations
19. 19*

    The semileptonic decays ${\eta }^{(\prime )}\to {\pi }^0{\ell }^{+}{\ell }^{-}$ and ${\eta }^{\prime }\to \eta {\ell }^{+}{\ell }^{-}$ in the standard model

    Hannah Schäfer🇩🇪 · Marvin Zanke🇩🇪 · Yannis Korte🇩🇪 · Bastian Kubis🇩🇪

    We perform a theoretical analysis of the semileptonic decays ${\eta }^{(\prime )}\to {\pi }^0{\ell }^{+}{\ell }^{-}$ and ${\eta }^{\prime }\to \eta {\ell }^{+}{\ell }^{-}$, where $\ell =e,\mu$, via a charge-conjugation-conserving two-photon mechanism. The underlying form factors are modeled using vector-meson dominance, phenomenological input, and $\mathrm{U}(3)$ flavor symmetry. We consider both a monopole and a dipole model, the latter tailored such that the expected high-energy behavior is ensured. Furthermore, we benchmark the effect of $S$-wave rescattering contributions to the decays. We infer significant effects of the form factors neglected in the literature so far, still finding branching ratios of the various decays well below the current experimental upper limits.

    hep-phhep-exnucl-thPRD(2023)·23 citations
20. 20*

    Higgs Criticality beyond the Standard Model

    Thomas Steingasser🇺🇸 · David I. Kaiser🇺🇸

    Both parameters in the Higgs field's potential, its mass and quartic coupling, appear fine-tuned to near-critical values, which gives rise to the hierarchy problem and the metastability of the electroweak vacuum. Whereas such behavior appears puzzling in the context of particle physics, it is a common feature of dynamical systems, which has led to the suggestion that the parameters of the Higgs potential could be set through some dynamical process. In this article, we discuss how this notion could be extended to physics beyond the Standard Model (SM). We first review in which sense the SM Higgs parameters can be understood as near-critical and show that this notion can be extrapolated in a unique way for a generic class of SM extensions. Our main result is a prediction for the parameters of such models in terms of their corresponding Standard Model effective field theory Wilson coefficients and corresponding matching scale. For generic models, our result suggests that the scale of new (bosonic) physics lies close to the instability scale. We explore the potentially observable consequences of this connection, and illustrate aspects of our analysis with a concrete example. Lastly, we discuss implications of our results for several mechanisms of dynamical vacuum selection associated with various Beyond-Standard-Model (BSM) constructions.

    hep-phhep-thPRD(2023)·29 citations
21. 21*

    Quadratic Coupling of the Axion to Photons

    Carl Beadle🇨🇭 · Sebastian A. R. Ellis🇨🇭 · Jérémie Quevillon🇫🇷 · Pham Ngoc Hoa Vuong🇩🇪

    We show that the QCD axion couples to the electromagnetic kinetic term at one loop. The result is that if axions make up dark matter, they induce temporal variation of the fine structure constant $\alpha$, which is severely constrained. We recast these constraints on the QCD axion parameter space. We also discuss how to generalise our finding to axion-like particles, and the resulting constraints.

    hep-phPRD(2024)·49 citations
22. 22*

    Comprehensive exploration of t-channel simplified models of dark matter

    Chiara Arina🇧🇪 · Benjamin Fuks🇫🇷 · Jan Heisig🇩🇪 · Michael Krämer🇩🇪 · Luca Mantani🇬🇧 · Luca Panizzi🇮🇹

    We analyse six classes of t-channel dark matter simplified models in which the Standard Model field content is extended by a coloured mediator and a dark matter state. The two new states are enforced to be odd under a new parity, while all Standard Model fields are taken even so that dark matter stability is guaranteed. We study several possibilities for the spin of the new particles and the self-conjugate property of the dark matter, and we focus on model configurations in which the dark matter couples to the right-handed up quark for simplicity. We investigate how the parameter spaces of the six models can be constrained by current and future cosmological, astrophysical and collider searches, and we highlight the strong complementary between those probes. Our results demonstrate that scenarios featuring a complex (non self-conjugate) dark matter field are excluded by cosmology and astrophysics alone, the only possibility to avoid these bounds being to invoke very weak couplings and mechanisms such as conversion-driven freeze-out. For models with self-conjugate dark matter, mediator and dark matter masses are pushed deep into the TeV regime, with the lower limits on the mediator mass reaching 3 to 4 TeV and those on the dark matter mass 1 to 2 TeV. In large parts of the parameter space these strong bounds are driven by same-sign mediator pair production, a channel so far not considered in the experimental analyses embedding t-channel dark matter model interpretations.

    hep-phhep-exPRD(2023)·25 citations
23. 23*

    Hide and seek: how PDFs can conceal New Physics

    Elie Hammou🇬🇧 · Zahari Kassabov🇬🇧 · Maeve Madigan🇩🇪 · Michelangelo L. Mangano🇨🇭 · Luca Mantani🇬🇧 · James Moore🇬🇧 · Manuel Morales Alvarado🇬🇧 · Maria Ubiali🇬🇧

    The interpretation of LHC data, and the assessment of possible hints of new physics, require the precise knowledge of the proton structure in terms of parton distribution functions (PDFs). We present a systematic methodology designed to determine whether and how global PDF fits might inadvertently 'fit away' signs of new physics in the high-energy tails of the distributions. We showcase a scenario for the High-Luminosity LHC, in which the PDFs may completely absorb such signs of new physics, thus biasing theoretical predictions and interpretations. We discuss strategies to single out the effects in this scenario, and disentangle the inconsistencies that stem from them. Our study brings to light the synergy between the high luminosity programme at the LHC and future low-energy non-LHC measurements of large-$x$ sea quark distributions. The analysis code used in this work is made public so that any users can test the robustness of the signal associated to a given BSM model against absorption by the PDFs.

    hep-phJHEP(2023)·59 citations
24. 24*

    A global analysis of axion-like particle interactions using SMEFT fits

    Anke Biekötter🇩🇪 · Javier Fuentes-Martín🇪🇸 · Anne Mareike Galda🇩🇪 · Matthias Neubert🇺🇸

    In the presence of an axion or axion-like particle (ALP) that couples to the Standard Model via dimension-five interactions, dimension-six SMEFT interactions are generated via renormalization-group evolution. As many of these SMEFT contributions are experimentally tightly constrained, this "ALP-SMEFT interference" can be used to derive indirect bounds on the ALP couplings to the Standard Model particles. We present a global analysis of the Wilson coefficients of the ALP effective Lagrangian based on Higgs, top, and low-energy data. The obtained bounds are model independent and are competitive or even stronger than direct bounds in the GeV to TeV ALP-mass range.

    hep-phJHEP(2023)·31 citations
25. 25*

    A complete tree-level dictionary between simplified BSM models and SMEFT (d $\le$ 7) operators

    Xu-Xiang Li🇨🇳 · Zhe Ren🇨🇳 · Jiang-Hao Yu

    Finding all possible UV resonances of effective operators is an important task in the bottom-up approach of effective field theory. We present all the tree-level UV resonances for the dimension-5, -6 and -7 operators in the Standard Model effective field theory (SMEFT), and then obtain the correspondence between the UV resonances and the effective operators from the relations among their Wilson coefficients, through the functional matching and operator reduction procedure. This provides a cross-dimension UV/IR dictionary for the SMEFT at tree-level, and the methods used here, especially the on-shell construction of general UV Lagrangian and the systematic reduction of operators, are extendable for UV resonances of $d\ge 8$ operators in SMEFT and other EFTs.

    hep-phPRD(2024)·34 citations
26. 26*

    Neutrinos from GRB 221009A: producing ALPs and explaining LHAASO anomalous $\gamma$ event

    Nicolás Bernal🇦🇪 · Yasaman Farzan🇮🇷 · Alexei Yu. Smirnov🇩🇪

    We propose a novel explanation for the 18 TeV gamma ray from GRB 221009A observed by LHAASO. High-energy neutrinos are converted into axion-like particles (ALPs) via their interaction with the cosmic neutrino background. Subsequently, ALPs are converted into high-energy photons in the magnetic field of our galaxy. We compute the fluxes of neutrinos, ALPs, and photons reaching Earth. IceCube's constraints on the neutrino flux from GRB 221009A translate into a severe upper bound on the photon flux. We find a range of parameters where all existing bounds are satisfied and the 18 TeV LHAASO photon can be explained. In the future, the specific correlation between the photon and neutrino flux reaching Earth from powerful neutrino sources with energies larger than 10 TeV such as GRBs or AGNs, can be used as a tool to differentiate our explanation from the alternatives suggested in the literature. We discuss how the interactions of our scenario can be embedded within electroweak gauge-invariant models, avoiding various cosmological and terrestrial bounds. We comment on the possibility of explaining the 251 TeV photon observed by the Carpet-2 detector, taking into account the bounds from the observation of high-energy neutrinos from TXS 0506+056.

    hep-phastro-ph.HEJCAP(2023)·5 citations
27. 27*

    Bulk viscosity of rotating, hot and dense spin 1/2 fermionic systems from correlation functions

    Sarthak Satapathy🇮🇳

    In this work we have presented the one-loop calculation of the bulk viscosity of a system of rotating, hot and dense spin 1/2 fermions within the framework of Kubo formalism calculated from correlation functions of fields which in turn is used to calculate the spectral function of energy-momentum tensors. The calculation has been done in curved space by the help of tetrad formalism, where the the gamma matrices in this set-up assume their generic structure by becoming space dependent. The techniques of thermal field theory have been employed which take into account the three energy scales viz. temperature, chemical potential and angular velocity into account in the Matsubara frequency summation. The study has been performed in the ambience of very large angular velocities, ranging from 0.1 to 1.0 GeV. The fermion propagator used in this work is appropiate for the regime of large angular velocities. We explore the behaviour of bulk viscosity with angular velocity, temperature and chemical potential through our plots.

    ↳ nucl-thhep-ph3 citations
28. 28*

    Inclusion of $K\Lambda$ electroproduction data in a coupled channel analysis

    M. Mai🇺🇸 · J. Hergenrather🇺🇸 · M. Döring🇺🇸 · T. Mart🇮🇩 · Ulf-G. Meißner🇩🇪 · D. Rönchen🇩🇪 · R. Workman🇺🇸

    Exclusive electroproduction reactions provide an access to the structure of excited baryons. To extract electroproduction multipoles encoding this information, the Jülich-Bonn-Washington (JBW) analysis framework is extended to the analysis of differential cross sections in $K\Lambda$ electroproduction. This update enlarges the scope of previous coupled-channel analyses of pions and eta mesons, with photoproduction reactions as boundary condition in all analyzed electroproduction reactions. Polarization observables are predicted and compared to recent CLAS data. The comparison shows the relevance of these data to pin down baryon properties.

    ↳ nucl-thhep-phnucl-exEPJA(2023)·20 citations
29. 29*

    Neutrino spin oscillations in a magnetized Polish doughnut

    Maxim Dvornikov (IZMIRAN)🇷🇺

    We study the gravitational scattering of ultrarelativistic neutrinos off a rotating supermassive black hole (BH) surrounded by a thick magnetized accretion disk. Neutrinos interact electroweakly with background matter and with the magnetic field in the disk since neutrinos are supposed to possess nonzero magnetic moments. The interaction with external fields results in neutrino spin oscillations. We find that the toroidal magnetic field, inherent in the magnetized Polish doughnut, does not cause a significant spin-flip for any reasonable strengths of the toroidal component. The reduction of the observed neutrino flux, owing to neutrino spin oscillations, is predicted. A poloidal component of the magnetic field gives the main contribution to the modification of the observed flux. The neutrino interaction with matter, rotating with relativistic velocities, also changes the flux of neutrinos. We briefly discuss the idea of the neutrino tomography of magnetic field distributions in accretion disks near BHs.

    ↳ astro-ph.HEgr-qchep-phJCAP(2023)·6 citations
30. 30*

    Unraveling Cosmological Anisotropies within Stochastic Gravitational Wave Backgrounds

    Yanou Cui🇺🇸 · Soubhik Kumar🇺🇸 · Raman Sundrum🇺🇸 · Yuhsin Tsai🇺🇸

    Identifying the anisotropies in a cosmologically sourced stochastic gravitational wave background (SGWB) would be of significance in shedding light on the nature of primordial inhomogeneities. For example, if SGWB carries isocurvature fluctuations, it would provide evidence for a multi-field inflationary origin of these inhomogeneities. However, this is challenging in practice due to finite detector sensitivity and also the presence of the astrophysical foregrounds that can compete with the cosmological signal. In this work, we explore the prospects for measuring cosmological SGWB anisotropies in the presence of an astrophysical counterpart and detector noise. To illustrate the main idea, we perform a Fisher analysis using a well-motivated cosmological SGWB template corresponding to a first order phase transition, and an astrophysical SGWB template corresponding to extra-galactic binary mergers, and compute the uncertainty with which various parameters characterizing the isotropic and anisotropic components can be extracted. We also discuss some subtleties and caveats involving shot noise in the astrophysical foreground. Overall, we show that upcoming experiments, e.g., LISA, Taiji, Einstein Telescope, Cosmic Explorer, and BBO, can all be effective in discovering plausible anisotropic cosmological SGWBs.

    ↳ astro-ph.COgr-qchep-phJCAP(2023)·19 citations
31. 31*

    Axion Flux Monodromy Discharges Relax the Cosmological Constant

    Nemanja Kaloper🇺🇸

    Linear axion monodromy models modulated with higher powers of fields naturally realize the quantum-mechanical flux discharge mechanism for relaxing the cosmological constant toward zero. Working with multiple copies of superposed linear and quadratic flux monodromies, each copy spanned by a pair of fluxes, we show that when the axion is very massive and so effectively decoupled, the membrane discharges relax the cosmological constant toward an attractor $0<\Lambda /{\text{mpl}}^4\ll 1$. If we restrict the flux variations and the intermediate flux values to never venture beyond a finite flux range, the terminal value of the cosmological constant will be tiny but finite. We show how it can reproduce the observed scale of dark energy, and explain how to incorporate matter sector phase transitions.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2023)·10 citations
32. 32*

    Do Neutrinos Become Flavor Unstable Due to Collisions with Matter in the Supernova Decoupling Region?

    Shashank Shalgar🇩🇰 · Irene Tamborra🇩🇰

    In core-collapse supernovae, the neutrino density is so large that neutrino flavor instabilities, leading to flavor conversion, can be triggered by the forward scattering of neutrinos among each other, if a crossing between the angular distributions of electron neutrinos and antineutrinos exists (fast instability in the limit of vanishing vacuum frequency) or in the presence of perturbations induced by the neutrino vacuum frequency (slow instability). Recently, it has been advanced the conjecture that neutrino collisions with the medium could be another mean to kickstart flavor change (collisional instability). Inspired by a spherically symmetric core-collapse supernova model with mass $18.6M_{\odot }$, we compute the neutrino angular distributions solving the kinetic equations for an average energy mode and investigate the occurrence of flavor instabilities at different post-bounce times, ranging from the accretion phase to the early cooling phase. We find that fast and slow flavor instabilities largely dominate over the collisional ones in the decoupling region for all post-bounce times. While more work is needed to assess the relevance of collisional instabilities in neutrino-dense environments, our findings suggest that neutrino collisions with matter affect the flavor evolution in the decoupling region, but are not responsible for triggering flavor conversion, if crossings in the neutrino lepton number angular distribution exist.

    ↳ astro-ph.HEhep-phPRD(2024)·28 citations
33. 33*

    How Gubser flow ends in a holographic conformal theory

    Avik Banerjee🇫🇷 · Toshali Mitra🇮🇳 · Ayan Mukhopadhyay🇮🇳 · Alexander Soloviev🇸🇮

    Gubser flow is an axis-symmetric and boost-invariant evolution in a relativistic quantum field theory which is best studied by mapping ${\mathbf{R}}^{3,1}$ to $d{S}_3\times \mathbf{R}$ when the field theory has conformal symmetry. We show that at late de-Sitter time, which corresponds to large proper time and central region of the future wedge within ${\mathbf{R}}^{3,1}$, the holographic conformal field theory plasma can reach a state in which $\epsilon =P_T=-P_L$, with $\epsilon$, $P_T$ and $P_L$ being the energy density, transverse and longitudinal pressures, respectively. We further determine the full sub-leading behaviour of the energy-momentum tensor at late time. Restricting to flows in which the energy density decays at large transverse distance from the central axis in ${\mathbf{R}}^{3,1}$, we show that this decay should be faster than any power law. Furthermore, in this case the energy density also vanishes in ${\mathbf{R}}^{3,1}$ faster than any power as we go back to early proper time. Hydrodynamic behavior can appear in intermediate time.

    ↳ hep-thgr-qchep-phEPJC(2024)·7 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.