Mon·Oct 9, 2023Monday·October 9, 2023

1. 01*

   Self-interacting Dark Matter in Non-Standard Cosmology

   Manoranjan Dutta (North Lakhimpur College (Autonomous))🇮🇳

   Discrepancies of the $\Lambda \mathrm{CDM}$ model with small-scale cosmological observations and stringent constraints from direct search experiments cast doubts over typical weak scale cold dark matter candidates e.g. WIMPs. Self-interacting dark matter (SIDM) is a very promising alternative to WIMP, which not only alleviates the small-scale anomalies of the $\Lambda \mathrm{CDM}$ model, but also matches with the highly accurate large-scale $\Lambda \mathrm{CDM}$ predictions. The small-scale anomalies can be resolved with a self-scattering cross-section $\sigma /m_{DM}\sim 1c{m}^2/gm$. Such large cross-sections can be realised in models of DM with a light MeV scale mediator and a sizeable coupling. We assume the DM to be Dirac fermion and the mediator to be either a light scalar or vector boson. In a standard cosmological history, one major issue with such models is to realise the correct relic density of dark matter via thermal freeze-out as the DM annihilates efficiently to the light mediators and ends up with an under-abundant relic. However, we show that, if the expansion rate of the universe is not radiation-dominated (RD) during the epoch of SIDM freeze-out, its relic abundance is enhanced significantly. We assume a non-standard expansion history of the universe by introducing a non-radiation like component in the early universe. In such a scenario, DM freezes out at an earlier epoch resulting in enhanced DM abundance, which can be matched with the correct relic density with suitable model parameters. The light mediator can also couple to an SM mediator and pave a way to detect SIDM at terrestrial laboratories. The mixing between the mediators can be constrained by data from direct search experiments. We find out the viable parameter space for a generic SIDM model taking into account the relevant phenomenological and experimental constraints.

   hep-phJ.Phys.Conf.Ser.(2025)·1 citation
2. 02*

   Integration-by-parts identities and differential equations for parametrised Feynman integrals

   Daniele Artico🇩🇪 · Lorenzo Magnea🇮🇹

   Integration-by-parts (IBP) identities and differential equations are the primary modern tools for the evaluation of high-order Feynman integrals. They are commonly derived and implemented in the momentum-space representation. We provide a different viewpoint on these important tools by working in Feynman-parameter space, and using its projective geometry. Our work is based upon little-known results pre-dating the modern era of loop calculations: we adapt and generalise these results, deriving a very general expression for sets of IBP identities in parameter space, associated with a generic Feynman diagram, and valid to any loop order, relying on the characterisation of Feynman-parameter integrands as projective forms. We validate our method by deriving and solving systems of differential equations for several simple diagrams at one and two loops, providing a unified perspective on a number of existing results.

   hep-phhep-thJHEP(2024)·22 citations
3. 03*

   The ${\chi }_{c1}(4274)$ multiplicity in heavy-ion collisions

   L.M. Abreu🇧🇷 · A.L.M. Britto🇧🇷 · F.S. Navarra🇧🇷 · H.P.L. Vieira🇧🇷

   In a previous work we computed the thermally-averaged cross sections for the production and absorption of the ${\chi }_{c1}(4274)$ state in the hot hadron gas formed in heavy ion collisions. In the present work we estimate the final yield of this exotic state in these collisions. We use the coalescence model to fix the initial multiplicities. The state is is treated as a $P-$wave bound state of $D_s{\bar{D}}_{s0}$ and also as a compact tetraquark. The Bjorken picture is used to model the hydrodynamic expansion and cooling. Then, the kinetic equation is solved to evaluate the time evolution of the ${\chi }_{c1}(4274)$ yield during the hot hadron gas phase. Since the ${\chi }_{c1}(4274)$ decay width is large it might decay inside the hadron gas. Therefore we also include the $ch{i}_{c1}(4274)$ decay and regeneration terms by means of an effective coupling, estimated from the available data. The combined effects of hadronic interactions and the ${\chi }_{c1}(4274)$ decay have a strong impact on the final yield. Also, predictions of the ${\chi }_{c1}(4274)$ multiplicity as a function of centrality and of the charged hadron multiplicity (measured at midrapidity) are presented. Finally, we calculate the yield of a proposed $P-$wave molecular state of $D_s\overline{D_{s0}}$, $Y^{\prime }(4274)$, characterized by a smaller width and smaller coupling constant obtained from the Weinberg compositeness condition.

   hep-phPRD(2024)·5 citations
4. 04*

   Reduced cross sections of electron and neutrino charged current quasielastic scattering on nuclei

   A.V. Butkevich🇷🇺

   The semi-exclusive averaged reduced cross sections for (anti)neutrino charged current quasi-elastic scattering on carbon, oxygen, and argon are analyzed within the relativistic distorted wave impulse approximation. We found that these cross sections as functions of missing nucleon energy are similar to those of electron scattering and are in agreement with electron scattering data for three nuclei. The difference between the electron and neutrino cross sections can be attributed to Coulomb distortion on the electron wave function. The averaged reduced cross sections depend slowly upon incoming lepton energy. The approach presented in this paper provide novel constraints on nuclear models of quasi-elastic neutrino-nucleus scattering and can be easily applied to test spectral functions and final state interactions, employed in neutrino event generators.

   hep-phnucl-thPRC(2024)·4 citations
5. 05*

   Neutrino CP Measurement in the Presence of RG Running with Mismatched Momentum Transfers

   Shao-Feng Ge🇨🇳 · Chui-Fan Kong🇨🇳 · Pedro Pasquini🇯🇵

   The neutrino mixing parameters are expected to have RG running effect in the presence of new physics. If the momentum transfers at production and detection mismatch with each other, the oscillation probabilities are generally modified and become dependent on not just the neutrino energy but also the momentum transfer. Even in the limit of vanishing baseline, the transition probability for the appearance channel is interestingly not zero. This would significantly affect the sensitivity of the genuine leptonic Dirac CP phase. We further explore the possibility of combing the long- and short-baseline neutrino experiments to constrain such RG running effect for the purpose of guaranteeing the CP measurement. To simulate the double dependence on the neutrino energy and momentum transfer, we extend the usual GLoBES simulation of fixed baseline experiments and use a two-dimensional ${\chi }^2$ analysis to obtain sensitivities.

   hep-phhep-exPRD(2024)·5 citations
6. 06*

   The Dilatonic Dynamics of Baryonic Crystals, Branes and Spheres

   Jahmall Bersini🇯🇵 · Alessandra D'Alise🇮🇹 · Matias Torres🇮🇹 · Francesco Sannino🇮🇹

   We systematically analyze the impact of dilatonic dynamics on Skyrme spheres, crystals and branes. The effects of the dilatonic model parameters, encompassing different underlying near-conformal dynamics, on the macroscopic properties of Skyrmions such as their mass and radius, are discussed. For spheres and crystals we identify special values of the ratio of the decay constants for which the second order differential equations reduce to a solvable first order system. Additionally, in the case of the crystals, the dilaton presence spatially separates the baryon and isospin charge distributions. For branes, we show how the dilaton smooths out their configurations. Our results are expected to have wide implications from the study of near-conformal dynamics stemming from QCD-like theories to phenomenological investigations of nuclear matter in extreme regimes.

   hep-phhep-lathep-thnucl-thPRD(2024)·4 citations
7. 07*

   ${\bar{B}}^0\to {\bar{K}}^{(\ast )0}X$, $B^{-}\to K^{(\ast )-}X$, ${\bar{B}}_s^0\to \eta ({\eta }^{\prime },\varphi )X$ from the $X(3872)$ molecular perspective

   Wei-Hong Liang🇨🇳 · Ting Ban🇨🇳 · Eulogio Oset🇪🇸

   We study the decays ${\bar{B}}^0\to {\bar{K}}^{0}X$, $B^{-}\to K^{-}X$, ${\bar{B}}_s^0\to \eta ({\eta }^{\prime })X$, ${\bar{B}}^0\to {\bar{K}}^{\ast 0}X$, $B^{-}\to K^{\ast -}X$ , ${\bar{B}}_s^0\to \varphi X$, with $X\equiv X(3872)$, from the perspective of the $X(3872)$ being a molecular state made from the interaction of the $D^{\ast +}{D}^{-},D^{\ast 0}{\bar{D}}^0$ and $c.c.$ components. We consider both the external and internal emission decay mechanisms and find an explanation for the ${\bar{K}}^{0}X$ and $K^{-}X$ production rates, based on the mass difference of the charged and neutral $D^{\ast }\bar{D}$ components. We also find that the internal and external emission mechanisms add constructively in the ${\bar{B}}^0\to {\bar{K}}^{0}X$, $B^{-}\to K^{-}X$ reactions, while they add destructively in the case of ${\bar{B}}^0\to {\bar{K}}^{\ast 0}X$, $B^{-}\to K^{\ast -}X$ reactions. This feature explains the decay widths of the present measurements and allows us to make predictions for the unmeasured modes of ${\bar{B}}_s^0\to \eta ({\eta }^{\prime })X(3872)$ and $B^{-}\to K^{\ast -}X(3872)$. The future measurement of these decay modes will help us get a better perspective on the nature of the $X(3872)$ and the mechanisms present in production reactions of that state.

   hep-phPRD(2024)·7 citations
8. 08*

   Probing the hidden-bottom pentaquark resonances in photonuclear bottomonium production near threshold: differential observables

   E. Ya. Paryev🇷🇺

   We study the near-threshold ${\rm Y}(1S)$ meson photoproduction from protons and nuclei by considering incoherent direct non-resonant ($\gamma p\to {\rm Y}(1S)p$, $\gamma n\to {\rm Y}(1S)n$) and two-step resonant ($\gamma p\to P_{bi}^{+}\to {\rm Y}(1S)p$, $\gamma n\to P_{bi}^0\to {\rm Y}(1S)n$, $i=1$, 2, 3; $P_{b1}^{+,0}=P_b^{+,0}(11080)$, $P_{b2}^{+,0}=P_b^{+,0}(11125)$, $P_{b3}^{+,0}=P_b^{+,0}(11130)$) bottomonium production processes with the main goal of clarifying the possibility to observe the non-strange hidden-bottom pentaquark states $P_{bi}^{+,0}$ in this production via differential observables. We calculate the absolute excitation functions, energy and momentum distributions for the non-resonant, resonant and for the combined (non-resonant plus resonant) production of ${\rm Y}(1S)$ mesons on protons, on carbon and tungsten target nuclei at near-threshold incident photon beam energies by assuming the spin-parity assignments of the hypothetical hidden-bottom resonances $P_b^{+,0}(11080)$, $P_b^{+,0}(11125)$ and $P_b^{+,0}(11130)$ as $J^P=(1/2{)}^{-}$, $J^P=(1/2{)}^{-}$ and $J^P=(3/2{)}^{-}$ within four different realistic choices for the branching ratios of their decays to the ${\rm Y}(1S)p$ and ${\rm Y}(1S)n$ modes (0.125, 0.25, 0.5 and 1\%) as well as for two options for the background contribution. We demonstrate that the measurements of these combined observables on proton and nuclear targets in the near-threshold energy region in future experiments at the planned high-luminosity electron-ion colliders EIC and EicC in the US and China should provide evidence for the existence of the above hidden-bottom pentaquark resonances as well as clarify their decay rates.

   hep-phhep-exnucl-exnucl-thNPA(2024)·9 citations
9. 09*

   Loop-induced Higgs decays in two Higgs doublet scenarios: some observations

   Snehit Panghal🇮🇳 · Biswarup Mukhopadhyaya🇮🇳

   We study the decay of three neutral Higgs bosons into {\gamma}{\gamma} and Z{\gamma} in the four major types of two Higgs doublet models with CP conserved. Particular focus is made on the possibility of the width of the latter decay dominating over the former. For the 125-GeV scalar, such a possibility is mostly excluded when one imposes all theoretical and experimental constraints, other than the Higgs data at the Large Hadron Collider. For the other CP-even neutral scalar, there remain regions in each kind of model where the Z{\gamma} mode dominates. For the CP-odd state, this possibility is restricted to only the models of Types II and Y, in certain regions of the parameter space.

   hep-ph4 citations
10. 10*

    A new way of reducing negative weights in MC@NLO

    Rikkert Frederix🇸🇪 · Paolo Torrielli🇮🇹

    We introduce a new technique, that we dub Born spreading, aimed at reducing the number of negative-weight $\mathbb{S}$ events in the MC@NLO matching of NLO calculations with parton-shower simulations. We show that such a technique, based on a re-distribution of Born matrix elements in the radiative phase space, achieves a sizeable reduction of negative-weight events at little computational cost. The method does not induce any biases in physical distributions.

    hep-phEPJC(2023)·16 citations
11. 11*

    New Probes of Electron--Muon Universality in $B\to K{\ell }^{+}{\ell }^{-}$ Decays

    Robert Fleischer (1,2)🇳🇱 · Eleftheria Malami (1,3)🇳🇱 · Anders Rehult (1,2)🇳🇱 · K. Keri Vos (1,4) ((1) Nikhef, Amsterdam, Netherlands, (2) Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Netherlands, (3) Center for Particle Physics Siegen (CPPS), Universität Siegen, Germany, (4) Gravitational Waves and Fundamental Physics (GWFP), Maastricht University, the Netherlands)

    In the pursuit of physics beyond the Standard Model, a promising path is the study of B-meson decays caused by the transition $b\to s{\ell }^{+}{\ell }^{-}$. A key observable in such decays is the ratio $R_K$, which measures electron--muon universality in $B\to K{\mu }^{+}{\mu }^{-}/e^{+}{e}^{-}$. At first sight, the recent LHCb measurement of $R_K\sim 1$ may seem to largely constrain deviations from universality in these decays. However, we show that this is actually not the case: new sources of CP violation allow for significant universality violation consistent with $R_K\sim 1$. This provides an exciting new opportunity to search for New Physics by measuring differences between CP asymmetries in $B\to K{\mu }^{+}{\mu }^{-}$ and $B\to K{e}^{+}{e}^{-}$.

    hep-phhep-exPoS(2024)·2 citations
12. 12*

    Revealing the mystery of the double charm tetraquark in $pp$ collision

    Xue-Li Hua🇨🇳 · Yi-Yao Li🇨🇳 · Qian Wang🇨🇳 · Shuai Yang🇨🇳 · Qiang Zhao🇨🇳 · Bing-Song Zou🇨🇳

    A novel approach is proposed to probe the nature of the double charm tetraquark through the prompt production asymmetry between $T_{\bar{c}\bar{c}}^{-}$ and $T_{cc}^{+}$ in $pp$ collisions. When comparing two theoretical pictures, i.e. the compact tetraquark and hadronic molecular pictures, we find that the former one exhibits a significantly larger production asymmetry, enabling the unambiguous determination of the tetraquark's internal structure. Additionally, distinctive differences in the transverse momentum and rapidity distributions of $T_{\bar{c}\bar{c}}^{-}$ and $T_{cc}^{+}$ cross sections emerge, particularly at $p_{\mathrm{T}}\approx 2\mathrm{GeV}$ and $y\approx \pm 6$ at a center-of-mass energy of 14$\mathrm{TeV}$. The insignificant asymmetry in hadronic molecular picture is because that hadronic molecules are produced in hadronic phase, where the phase space of their constituents needs to be taken into account rigorously. Our work can be extended to the exploration of other double heavy tetraquark candidates, offering a versatile approach to advance our understanding of exotic hadrons.

    hep-phEPJC(2024)·9 citations
13. 13*

    Two-loop five-particle scattering amplitudes

    Simone Zoia🇨🇭

    I discuss the recent advances in the computation of two-loop scattering amplitudes for five-particle processes. The latter are fundamental ingredients to obtain predictions at the next-to-next-to-leading order (NNLO) in QCD for many interesting LHC processes. I discuss the state-of-the-art technology for computing scattering amplitudes analytically, and present new results relevant for the LHC phenomenology.

    hep-phhep-thPoS(2024)·3 citations
14. 14*

    2$b$ or not 2$b$: on the rejection of $g\to b\bar{b}$ jets

    Enrico Lunghi🇺🇸 · Beni Pazar🇺🇸

    Motivated by new physics models which lead to final states containing a high multiplicity of bottom and top quarks, we develop a tagging strategy to suppress reducible and non-reducible multi-jet backgrounds. The idea takes advantage of the properties of light parton showers and of the gluon fragmentation into heavy quarks to reject jets that do not originate from a bottom quark.

    hep-phhep-exJHEP(2023)·1 citation
15. 15*

    Catalog variance of testing general relativity with gravitational-wave data

    Costantino Pacilio🇮🇹 · Davide Gerosa🇮🇹 · Swetha Bhagwat🇬🇧

    Combining multiple gravitational-wave observations allows for stringent tests of general relativity, targeting effects that would otherwise be undetectable using single-event analyses. We highlight how the finite size of the observed catalog induces a significant source of variance. If not appropriately accounted for, general relativity can be excluded with arbitrarily large credibility even if it is the underlying theory of gravity. This effect is generic and holds for arbitrarily large catalogs. Moreover, we show that it cannot be suppressed by selecting "golden" observations with large signal-to-noise ratios. We present a mitigation strategy based on bootstrapping (i.e. resampling with repetition) that allows assigning uncertainties to one's credibility on the targeted test. We demonstrate our findings using both toy models and real gravitational-wave data. In particular, we quantify the impact of the catalog variance on the ringdown properties of black holes using the latest LIGO/Virgo catalog.

    ↳ gr-qcastro-ph.HEhep-phphysics.data-anPRD(2024)·19 citations
16. 16*

    Negative Coupling ${\varphi }^4$ on the Lattice

    Paul Romatschke🇺🇸

    Triviality of ${\varphi }^4$ theory in four dimensions can be avoided if the bare coupling constant is negative in the UV. Theories with negative coupling can be put on the lattice if the integration domain for $\varphi (x)$ is contour-deformed from the real to the complex domain. In 0+1d (quantum mechanics), one can recover results from $\mathcal{P}\mathcal{T}$-symmetric quantum mechanics in this way. In this work, I report on an attempt to put negative coupling ${\varphi }^4$ theory in 4 dimensions on the lattice.

    ↳ hep-lathep-phhep-thnucl-thPoS(2024)·12 citations
17. 17*

    Vector dark matter, inflation and non-minimal couplings with gravity

    Ogan Özsoy🇪🇸 · Gianmassimo Tasinato🇬🇧

    We propose a cosmological dark matter production mechanism in the form of a longitudinal massive vector boson. We build upon the work of Graham et.al. including non-minimal couplings of the massive vector with gravity, developing a well motivated set-up from an effective field theory perspective. We carefully track the dynamics of vector field in passing from inflation to radiation dominated universe to show that the late time abundance of longitudinal modes -- excited initially by the quantum fluctuations during inflation -- can provide the observed dark matter abundance for sufficiently weak non-minimal coupling and wide range of vector masses $5\times 10^{-7}\lesssim m[\mathrm{eV}]\lesssim 5\times 10^3$. The final abundance of dark matter depends on two parameter, the vector mass and its non-minimal coupling with gravity. We discuss experimental venues to probe this framework, including the production of a stochastic gravitational wave background. The latter is especially interesting, as the same mechanism that generates dark matter can potentially lead to the production of gravitational waves in the LISA frequency band, through the second-order effects of large dark matter iso-curvature perturbations at small scales. We take a first step in this direction, identifying the potential information that gravitational wave experiments can provide on the parameter space of dark matter within this scenario.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2024)·41 citations
18. 18*

    Holographic Schwinger Effect in Anisotropic Media

    Jing Zhou🇨🇳 · Jun Chen🇨🇳 · Le Zhang🇨🇳 · Jialun Ping🇨🇳 · Xun Chen

    According to gauge/gravity correspondence, we study the holographic Schwinger effect within an anisotropic background. Firstly, the separate length of the particle-antiparticle pairs is computed within the context of an anisotropic background which is parameterized by dynamical exponent $\nu$. It is found that the maximum separate length $x$ increases with the increase of dynamical exponent $\nu$. By analyzing the potential energy, we find that the potential barrier increases with the dynamical exponent $\nu$ at a small separate distance. This observation implies that the Schwinger effect within an anisotropic background is comparatively weaker when contrasted with its manifestation in an isotropic background. Finally, we also find that the Schwinger effect in the transverse direction is weakened, compared to the parallel direction in the anisotropic background, which is consistent with the top-down model.

    ↳ hep-thhep-ph0 citations
19. 19*

    Impact of non-zero strangeness on thermodynamics of finite volume quark matter

    Nisha Chahal🇮🇳 · Suneel Dutt🇮🇳 · Arvind Kumar🇮🇳

    This paper investigates the impact of strangeness chemical potential and finite volume on QCD critical end point by employing a (2+1) flavored Polyakov quark meson model. Within the mean-field approximation, the model has been extended to study the effect of vector interactions on the thermodynamics of isospin-asymmetric quark matter. Susceptibilities of conserved charges like the quark and strangeness number are analyzed using Taylor's series expansion. The chiral phase transition boundary in the QCD phase diagram is found to be shifted towards higher values of the quark chemical potential (${\mu }_q$) and lower temperature (T) for decreasing system size. On the other hand, there is an opposite change to lower quark chemical potential and higher temperature for decreasing strangeness chemical potential.

    ↳ nucl-thhep-phPRD(2024)·1 citation
20. 20*

    Real-time dynamics of false vacuum decay

    Laura Batini🇩🇪 · Aleksandr Chatrchyan🇩🇪 · Jürgen Berges🇩🇪

    We investigate false vacuum decay of a relativistic scalar field initialized in the metastable minimum of an asymmetric double-well potential. The transition to the true ground state is a well-defined initial-value problem in real time, which can be formulated in nonequilibrium quantum field theory on a closed time path. We employ the non-perturbative framework of the two-particle irreducible (2PI) quantum effective action at next-to-leading order in a large-N expansion. We also compare to classical-statistical field theory simulations on a lattice in the high-temperature regime. By this, we demonstrate that the real-time decay rates are comparable to those obtained from the conventional Euclidean (bounce) approach. In general, we find that the decay rates are time dependent. For a more comprehensive description of the dynamics, we extract a time-dependent effective potential, which becomes convex during the nonequilibrium transition process. By solving the quantum evolution equations for the one- and two-point correlation functions for vacuum initial conditions, we demonstrate that quantum corrections can lead to transitions that are not captured by classical-statistical approximations.

    ↳ hep-thastro-ph.COgr-qchep-ph+1PRD(2024)·45 citations
21. 21*

    Towards a quantum field theory description of nonlocal spacetime defects

    Christopher D. Carone🇺🇸 · Noah L. Donald🇺🇸

    We propose an ansatz for encoding the physics of nonlocal spacetime defects in the Green's functions for a scalar field theory defined on a causal set. This allows us to numerically study the effects of nonlocal spacetime defects on the discrete Feynman propagator of the theory defined on the causal set in 1+1 dimensions, and to compare to the defect-free limit. The latter approaches the expected continuum result, on average, when the number of points becomes large. When defects are present, two points with the same invariant spacetime interval can have different propagation amplitudes, depending on whether the propagation is between two ordinary spacetime points, two defects, or a defect and an ordinary point. We show that a coarse-grained description that is only sensitive to the average effect of the defects can be interpreted as a defect-induced mass and wave-function renormalization of the scalar theory.

    ↳ gr-qchep-phhep-thClass.Quant.Grav.(2024)·1 citation

* 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.