Wed·Sep 22, 2021Wednesday·September 22, 2021

1. 01*

   Transverse momentum dependent operator expansion at next-to-leading power

   Alexey Vladimirov🇩🇪 · Valentin Moos🇩🇪 · Ignazio Scimemi🇪🇸

   We develop a method of transverse momentum dependent (TMD) operator expansion that yields the TMD factorization theorem on the operator level. The TMD operators are systematically ordered with respect to TMD-twist, which allows a certain separation of kinematic and genuine power corrections. The process dependence enters via the boundary conditions for the background fields. As a proof of principle, we derive the TMD factorization up to the next-to-leading power $(\sim q_T/Q)$ at the next-to-leading order for any process with two detected states.

   hep-phhep-thJHEP(2022)·61 citations
2. 02*

   Radiative ${\Xi }_b^{-}\to {\Xi }^{-}\gamma$ decay

   A. R. Olamaei🇮🇷 · K. Azizi🇮🇷

   Recently, the LHCb Collaboration performed first search for the rare radiative ${\Xi }_b^{-}\to {\Xi }^{-}\gamma$ decay and put an upper limit, $\mathcal{B}({\Xi }_b^{-}\to {\Xi }^{-}\gamma )<1.3\times 10^{-4}$, on its branching ratio. The measurement agrees well with existing theory prediction using SU(3) flavor symmetry method, but shows a slight tension with the previous prediction from light-cone sum rules. Inspired by this, we investigate this decay as well as other radiative decays of ${\Xi }_b^{0(-)}({\Xi }_b^{{}^{\prime }-})$ to ${\Xi }^{0(-)}$ and ${\Sigma }^{0(-)}$ baryons using the form factors calculated from light-cone QCD sum rules in full theory. we obtain $\mathcal{B}({\Xi }_b^{-}\to {\Xi }^{-}\gamma )=1.08_{-0.49}^{+0.63}\times 10^{-5}$, which lies below the upper limit set by LHCb and is consistent with flavor-symmetry driven prediction. Our predictions on other channels may be checked in experiment and by other phenomenological approaches.

   hep-phhep-exhep-latEPJC(2022)·6 citations
3. 03*

   Warning: The mini gamma-ray-bursts in planning hadron colliders beyond the LHC energies

   Wei Zhu🇨🇳 · Zhiyi Cui🇨🇳 · Jianhong Ruan🇨🇳

   Gluons may converge to a stable state at a critical momentum in nucleon. This gluon condensation will greatly increase the proton-proton cross section provided that the collision energies exceed the gluon condensation threshold. Based on the analyses of cosmic gamma-ray spectra, we find that the $p-Pb$ and $Pb-Pb$ collisions at the LHC are close to the energy region of the gluon condensation effect. We warn that for the next generation of hadron colliders increasing the collision energies, the extremely strong gamma-rays will be emitted in a narrow space of the accelerator due to the gluon condensation effect. Such artificial mini gamma-ray-bursts in the laboratory may damage the detectors.

   hep-phastro-ph.HEhep-exnucl-ex0 citations
4. 04*

   Chemical Freeze-out Parameters via a Non-perturbative QCD Approach

   Yi Lu🇨🇳 · Muyang Chen🇨🇳 · Zhan Bai🇨🇳 · Fei Gao🇩🇪 · Yu-xin Liu🇨🇳

   By analyzing the calculated baryon number susceptibility ratios ${\chi }_1^B/{\chi }_2^B$ and ${\chi }_3^B/{\chi }_1^B$ in two-flavor system via the Dyson-Schwinger equation approach of QCD, we determine the chemical freeze-out temperature and baryon chemical potential in cases of both thermodynamic limit and finite size. We calculate the center-of-mass energy dependence of the ${\chi }_4^B/{\chi }_2^B(\kappa {\sigma }^2)$ at the freeze-out line and find an excellent agreement with experimental data when taking into account the finite size effect. Our calculations indicate that the $\kappa {\sigma }^2$ exhibits a nonmonotonic behavior in lower collision energy region. We also predict that the collision energy dependence of ${\chi }_6^B/{\chi }_2^B$ is nonmonotonic.

   hep-phPRD(2022)·6 citations
5. 05*

   Polarization measurement for the dileptonic channel of $W^{+}{W}^{-}$ scattering using generative adversarial network

   Jinmian Li🇨🇳 · Cong Zhang🇨🇳 · Rao Zhang🇨🇳

   Measuring the polarization fractions of the $W^{+}{W}^{-}$ scattering reveals the interactions of the Higgs boson as well as new neutral states that are related to the standard model electroweak symmetry breaking. The dileptonic channel has a relatively lower background rate, but the kinematics of its final states can not be fully reconstructed due to the presence of two neutrinos. We propose neural networks to establish maps between the distributions of measurable quantities and the distributions of the lepton angles in $W$ boson rest frames. New physics contributions and collision energy can largely affect the kinematic properties of the $W^{+}{W}^{-}$ scattering beside the lepton angles. To make the network in ignorance of that information, the loss function is modified in two different ways. We show that the networks are promising in reproducing the lepton angle distributions, and the precision of the fitted polarization fractions obtained from network predictions is comparable to that obtained with the truth lepton angle. Although the best-fit values of polarization fractions do not change much after including the background uncertainty, the precisions is substantially reduced. Our trained models are available at GitHub.

   hep-phhep-exPRD(2022)·9 citations
6. 06*

   Gravitational waves from holographic QCD phase transition with gluon condensate

   Zhou-Run Zhu🇨🇳 · Jun Chen🇨🇳 · Defu Hou🇨🇳

   In this paper, we discuss the holographic first order QCD phase transition with gluon condensate and the generation of gravitational waves (GWs) from the phase transition. The first order QCD phase transition is dual to the first order Hawking-Page phase transition from holography. We study the first order Hawking-Page phase transition from the thermal dilatonic phase to the dilatonic black hole phase and find the phase transition temperature is proportional to the gluon condensate. After substituting into the phenomenological value of gluon condensate from QCD sum rules, we find $T_c=155.38MeV$. In further research, we study the GWs generated from holographic cosmic first order QCD phase transition with gluon condensate and the produced GWs might be detected by the International Pulsar Timing Array, Square Kilometre Array and Big-Bang Observer. Moreover, the gluon condensate suppresses the energy density of total GWs and peak frequency.

   hep-phEPJA(2022)·23 citations
7. 07*

   Quark Number Fluctuations at Finite Temperature and Finite Chemical Potential via the Dyson-Schwinger Equation Approach

   Xian-yin Xin🇨🇳 · Si-xue Qin🇨🇳 · Yu-xin Liu🇨🇳

   We investigate the quark number fluctuations up to the fourth order in the matter composed of two light flavor quarks with isospin symmetry and at finite temperature and finite chemical potential using the Dyson-Schwinger equation approach of QCD. In order to solve the quark gap equation, we approximate the dressed quark-gluon vertex with the bare one and adopt both the Marris-Tandy (MT) model and the infrared constant (Qin-Chang) model for the dressed gluon propagator. Our results indicate that the second, third, and forth order fluctuations of net quark number all diverge at the critical end point (CEP). Around the CEP, the second order fluctuation possesses obvious pump while the third and fourth order ones exhibit distinct wiggles between positive and negative. For the MT model and the Qin-Chang model, we give the pseudo-critical temperature at zero quark chemical potential as $T_c=146$ MeV and $150$ MeV, and locate the CEP at $({\mu }_E^q,T_E^{})=(120,124)$ MeV and $(124,129)$ MeV, respectively. In addition, our results manifest that the fluctuations are insensitive to the details of the model, but the location of the CEP shifts to low chemical potential and high temperature as the confinement length scale increases.

   hep-phPRD(2014)·83 citations
8. 08*

   Investigation of hidden-charm pentaquarks with strangeness $S=-1$

   Xiaohuang Hu🇨🇳 · Jialun Ping🇨🇳

   Recently, a new hidden-charm pentaquark state $P_{cs}(4459)$ was reported by the LHCb Collaboration. Stimulated by the fact that all hidden-charm pentaquark states in $S=0$ systems were successfully predicted by our chiral quark model, we extended this study to the $S=-1$ systems. All possible quantum numbers $I{J}^P=0(\frac{1}{2}{)}^{-}$, $0(\frac{3}{2}{)}^{-}$, $0(\frac{5}{2}{)}^{-}$, $1(\frac{1}{2}{)}^{-}$, $1(\frac{3}{2}{)}^{-}$ and $1(\frac{5}{2}{)}^{-}$ have been investigated. The calculation results shows that the newly observed state $P_{cs}(4459)$ can be explained as ${\Xi }_c{\bar{D}}^{\ast }$ molecular state and the quantum number is $0(\frac{1}{2}{)}^{-}$. In addition, we also find other molecular states ${\Xi }_c\bar{D}$, ${\Xi }_c^{\ast }\bar{D}$ and ${\Xi }_c^{\prime }{\bar{D}}^{\ast }$. It is worth mentioning that ${\Xi }_c{\bar{D}}^{\ast }$ can form a two-peak structure from states in system $0(\frac{1}{2}{)}^{-}$ and $0(\frac{3}{2}{)}^{-}$. The decay width of all molecular states is given with the help of real scaling method. These hidden-charm pentaquark states is expected to be further verified in future experiments.

   hep-phEPJC(2022)·42 citations
9. 09*

   Bounds on the absorptive parts of the chromomagnetic and chromoelectric dipole moments of the top quark from LHC data

   A. I. Hernández-Juárez🇲🇽 · A. Moyotl🇲🇽 · G. Tavares-Velasco🇲🇽

   Bounds on the absorptive (imaginary) parts of the top quark chromomagnetic ${\hat{\mu }}_t$ and chromoelectric ${\hat{d}}_t$ dipole moments are obtained by reinterpreting the most recent LHC data in top quark pair production. It is found that both limits are of the order of $10^{-1}-10^{-2}$, which are consistent with the standard model prediction of $\mathrm{Im}\left[{\hat{\mu }}_t\right]$. The effects of the absorptive parts of the top quark dipole moments are also studied via some kinematic distributions of $\bar{t}t$ production, though no significant deviation from the standard model leading order contribution is observed. Our bounds can be useful to constrain the parameter space of standard model extensions.

   hep-phEur.Phys.J.Plus(2022)·9 citations
10. 10*

    Triangle mechanism in the decay process $J/\psi \to K^{-}{K}^{+}{a}_1(1260)$

    Xuan Luo🇨🇳 · Dazhuang He🇨🇳 · Yiling Xie🇨🇳 · Hao Sun🇨🇳

    The role of triangle mechanism in the decay process $J/\psi \to K^{-}{K}^{+}{a}_1(1260)$ is probed. In this mechanism, a close-up resonance with mass $1823$ MeV and width $122$ MeV decays into $K^{\ast }\varphi ,K^{\ast }\to K\pi$ and then $K^{\ast }\bar{K}$ fuses into the $a_1(1260)$ resonance. We find that this mechanism leads to a triangle singularity around $M_{\mathrm{inv}}(K^{-}{a}_1(1260))\approx 1920$ MeV, where the axial-vector meson $a_1(1260)$ is considered as a dynamically generated resonance. With the help of the triangle mechanism we find sizable branching ratios $\text{Br}(J/\psi \to K^{-}{K}^{+}{a}_1(1260),a_1\to \pi \rho )=1.210\times 10^{-5}$ and $\text{Br}(J/\psi \to K^{-}{K}^{+}{a}_1(1260))=3.501\times 10^{-5}$. Such a effect from triangle mechanism of the decay process could be investigated by such as BESIII, LHCb and Belle-II experiments. This potential investigation can help us obtain the information of the axial-vector meson $a_1(1260)$.

    hep-phPRD(2021)·3 citations
11. 11*

    Probing the $L_{\mu }$-$L_{\tau }$ Gauge Boson at the MUonE Experiment

    Kento Asai🇯🇵 · Koichi Hamaguchi🇯🇵 · Natsumi Nagata🇯🇵 · Shih-Yen Tseng🇯🇵 · Juntaro Wada🇯🇵

    We discuss the prospects of probing the $L_{\mu }-L_{\tau }$ gauge boson at the MUonE experiment. The $L_{\mu }-L_{\tau }$ gauge boson $Z^{\prime }$ with a mass of $\lesssim 200$ MeV, which can explain the discrepancy between the measured value of the muon $g-2$ and the value calculated in the Standard Model, can be produced at the MUonE experiment through the process $\mu e\to \mu e{Z}^{\prime }$. The $Z^{\prime }$ in the final state decays into a pair of neutrinos, and therefore we cannot observe the decay of $Z^{\prime }$ directly. It is, however, still possible to probe this signature by searching for events with a large scattering angle of muon and a less energetic final-state electron. The background events coming from the elastic scattering $\mu e\to \mu e$ as well as radiative process $\mu e\to \mu e\gamma$ can be removed by the kinematical cuts on the muon scattering angle and the electron energy, in addition to a photon veto. The background events from the electroweak process $\mu e\to \mu e\nu \bar{\nu }$ are negligible. With our selection criteria, the number of signal events $\mu e\to \mu e{Z}^{\prime }$ is found to be as large as $\sim 10^3$ in the parameter region motivated by the muon $g-2$ discrepancy. It is, therefore, quite feasible to probe the $L_{\mu }-L_{\tau }$ gauge boson at the MUonE experiment -- without introducing additional devices -- and we strongly recommend recording the events relevant to this $Z^{\prime }$ production process.

    hep-phhep-exPRD(2022)·27 citations
12. 12*

    Holographic deconfined QGP phase diagram and entropy with an anomalous flow in a magnetic field background

    Jiali Deng🇨🇳 · Sheng-Qin Feng🇨🇳

    We assume that the initial hydrodynamic environment is a Quark Gluon Plasma (QGP) phase where merely u and d quarks are considered when adding a magnetic field. When considering the chiral magnetic effect in relativistic heavy ion collisions, an anomalous current will be formed in the QGP environment. The chiral magnetic current formed by these u and d quarks has an impact on the heavy quarkonium. By using fluid/gravity duality, the metric with anomalous flow is established by using fluid/gravity duality, so as to introduce the magnetic field effect into the corresponding metric. And then we use heavy quarkonium as a probe to study phase transition, and utilize the effective string tension of the heavy quarkonium to study phase transition by AdS/QCD theory. The characteristics of reporting inverse magnetic catalysis for the confinement-deconfinement transition with anomalous flow are in qualitative agreement with lattice QCD findings. The heavy-quarkonium asymptotic entropy distributions with different magnetic field around the confinement-deconfinement transition temperature are given in the paper.

    hep-phPRD(2022)·13 citations
13. 13*

    Multi Higgs production via photon fusion at future multi-TeV muon colliders

    Mauro Chiesa🇮🇹 · Barbara Mele🇮🇹 · Fulvio Piccinini🇮🇹

    Multi-TeV muon colliders promise an unprecedented potential for exploring the particle-physics energy frontier, and, at the same time, can probe with fantastic accuracy the precise structure of the Standard Model, and in particular of the Higgs boson sector. Here we consider the possibility to measure the loop-suppressed single-, double-, triple-Higgs boson production mediated by the collinear-photon scattering in the channels ${\mu }^{+}{\mu }^{-}\to {\mu }^{+}{\mu }^{-}{\gamma }^{\ast }{\gamma }^{\ast }\to {\mu }^{+}{\mu }^{-}[H,HH,HHH]$. We study total rates and kinematical distributions in the Standard Model, and compare them with the corresponding vector-boson-fusion processes $V^{\ast }{V}^{\ast }\to H,HH,HHH$ at muon collisions center-of-mass energies in the range between 1.5 and 100 TeV. Possible strategies for enhancing the $\gamma \gamma \to H,HH,HHH$ signal over the dominant vector-boson-fusion production are proposed. The sensitivity of total rates to possible anomalies in the Higgs-boson self-couplings is also discussed.

    hep-phEPJC(2024)·40 citations
14. 14*

    Holography of Strongly Coupled Gauge Theories

    Nick Evans🇬🇧

    The "periodic table" of strongly coupled gauge theories remains only sketchily understood. Holography has developed to the point where bottom up constructions can describe the spectrum of individual gauge theories (based on assumptions of their running) including quarks in different representations and higher dimension operators. I highlight the method with a "perfected" version of an AdS dual of QCD and results for composite higgs models with two representations of quarks. The method raises questions about the degree to which energy scales can be split in generic gauge theories including whether confinement and chiral symmetry breaking are linked.

    hep-phhep-thEPJ Web Conf.(2022)·3 citations
15. 15*

    Heavy states and electroweak effective approaches

    Ignasi Rosell🇪🇸 · Antonio Pich🇪🇸 · Juan José Sanz-Cillero🇪🇸

    The existence of a mass gap between the Standard Model (SM) and possible new states encourages us to use effective field theories. Here we follow the non-linear realization of the electroweak symmetry breaking: the electroweak effective theory (EWET), also known as Higgs effective field theory (HEFT) or electroweak chiral Lagrangian (EWChL). At short distances an effective resonance Lagrangian which couples the SM states to bosonic and fermionic resonances is considered. After integrating out the resonances and assuming a well-behaved high-energy behavior, we estimate or bound purely bosonic low-energy constants in terms of only resonance masses. Current experimental information on these low-energy constants allows us to constrain the high-energy resonance masses.

    hep-phPoS(2022)·0 citations
16. 16*

    Phase-Integral Formulation of Dynamically Assisted Schwinger Pair Production

    Chul Min Kim🇰🇷 · Alexander Fedotov🇷🇺 · Sang Pyo Kim🇰🇷

    We present a phase-integral formulation of dynamically assisted Schwinger pair production of scalar charges to find the pair production density under a strong low-frequency field and a weak high-frequency field. The leading WKB action was the Schwinger formula determined by the constant field, whose corrections are determined by the Keldysh parameter for the oscillating field, $m{\omega }_q/q{E}_q$. We found a systematic expression of the leading WKB action as a power series in the Keldysh parameter, of which coefficients are given as integrals of the product of fields in the complex time domain. For the case of a strong constant field superimposed with a weak oscillating field, we provided explicit formulas and proposed a procedure for numerical evaluation. The presented phase-integral formulation should provide a clear simple method for quantitatively analyzing the leading-order features of dynamically assisted Schwinger pair production.

    hep-phphysics.plasm-phquant-ph1 citation
17. 17*

    Tasting Flavoured Majorana Dark Matter

    Harun Acaroğlu🇩🇪 · Monika Blanke🇩🇪

    We study a simplified model of flavoured Majorana dark matter in the Dark Minimal Flavour Violation framework. The model extends the Standard Model by a dark matter flavour triplet and a scalar mediator, through which the new dark fermions couple to right-handed up-type quarks. This interaction is governed by a new coupling matrix $\lambda$ which is assumed to constitute the only new source of flavour and CP violation. We analyse the parameter space of this model by using constraints from collider searches, $D^0-{\bar{D}}^0$ mixing, cosmology and direct dark matter searches. Throughout our study, we point out crucial differences between the Majorana and Dirac dark matter cases. After performing a combined analysis within the context of all the experimental constraints mentioned above, we analyse which flavour for the dark matter particle is preferred by experimental data. We further investigate if this model is capable of explaining the large measured value of the direct CP asymmetry $\Delta A_{CP}^{\text{dir}}$ in charm decays. We find that significant enhancements with respect to the Standard Model expectation are compatible with all constraints, and even the central value of the measurement can be reached. We also advertise the flavour-violating final state with two same-sign top quarks produced in association with missing transverse energy as a smoking-gun signature for flavoured Majorana dark matter at the LHC.

    hep-phhep-exJHEP(2022)·19 citations
18. 18*

    Characterizing Heavy Neutral Fermions via their Decays

    André de Gouvêa🇺🇸 · Patrick J. Fox🇺🇸 · Boris J. Kayser🇺🇸 · Kevin J. Kelly🇺🇸

    Many extensions of the Standard Model of particle physics contain new electrically-neutral fermions. Should one of these particles be discovered, questions will naturally arise regarding its nature. For instance: is it a self-conjugate particle (i.e., is it a Dirac or a Majorana fermion)?, does it interact via the Standard Model force carriers or something else? One set of well-motivated particles in this class are Heavy Neutral Leptons (HNLs), Standard Model gauge-singlet fermions that mix with the neutrinos and may be produced in meson decays. We demonstrate that measuring the three body decays of the HNL (or phenomenologically similar heavy fermions) can help determine whether they are Majorana or Dirac fermions. We also investigate the ability to distinguish among different models for the physics responsible for the HNL decay. We compare the reach assuming full and partial event reconstruction, and propose experimental analyses. Should a new fermion be discovered, studying its three body decays provides a powerful diagnostic tool of its nature.

    hep-phhep-exPRD(2022)·13 citations
19. 19*

    Hunting for tetraquarks in ultra-pheripheral heavy ion collisions

    Angelo Esposito🇨🇭 · Claudio Andrea Manzari🇨🇭 · Alessandro Pilloni🇮🇹 · Antonio Davide Polosa🇮🇹

    Ultra-peripheral heavy ion collisions constitute an ideal setup to look for exotic hadrons because of their low event multiplicity and the possibility of an efficient background rejection. We propose to look for four-quark states produced by photon-photon fusion in these collisions at center-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}=5.5\mathrm{TeV}$. In particular, we focus on those states that would represent a definite smoking gun for the compact tetraquark model. We show that the $X(6900)$, a likely $cc\bar{c}\bar{c}$ compact state, is a perfect candidate for this search, and estimate a production cross section ranging from around $250$ nb to $1150$ nb, depending on its quantum numbers. Furthermore, we discuss the importance of ultra-peripheral collisions to the search for the scalar and tensor partners of the $X(3872)$ predicted by the diquarkonium model, and not yet observed. The completion of such a flavor-spin multiplet would strongly speak in favor of the compact tetraquark model.

    hep-phhep-exnucl-thPRD(2021)·33 citations
20. 20*

    Testing Exotic Scalars with HiggsBounds

    Henning Bahl🇩🇪 · Victor Martin Lozano🇩🇪 · Tim Stefaniak🇩🇪 · Jonas Wittbrodt🇸🇪

    The program HiggsBounds is a well-established tool for testing Beyond-the-Standard Model (BSM) theories with an extended Higgs sector against experimental limits from collider searches at LEP, Tevatron and LHC. Thus far, it could be applied to any neutral or charged Higgs bosons originating from the modified Higgs sector. Implicitly, these particles were assumed to exhibit a somewhat hierarchical Yukawa structure as present in the Standard Model, where in particular the couplings to first generation fermions could be neglected. In this work, we extend the HiggsBounds functionalities to go beyond these restrictions, thus making the code applicable to any neutral or charged BSM scalars. Moreover, we develop a new approach to implement experimental searches whose kinematic acceptance depends significantly on the values of the involved couplings. We achieve this by recasting the searches to general scalar models. Using this approach we incorporate relevant current experimental limits from LHC searches for exotic scalars, and present the implications of these limits for a dark matter scalar mediator model, a flipped Two-Higgs-Doublet Model and a supersymmetric model with R-parity violation.

    hep-phhep-exEPJC(2022)·41 citations
21. 21*

    Stellar Evolution confronts Axion Models

    Luca Di Luzio🇮🇹 · Marco Fedele🇩🇪 · Maurizio Giannotti🇺🇸 · Federico Mescia🇪🇸 · Enrico Nardi🇮🇹

    Axion production from astrophysical bodies is a topic in continuous development, because of theoretical progress in the estimate of stellar emission rates and, especially, because of improved stellar observations. We carry out a comprehensive analysis of the most informative astrophysics data, revisiting the bounds on axion couplings to photons, nucleons and electrons, and reassessing the significance of various hints of anomalous stellar energy losses. We confront the performance of various theoretical constructions in accounting for these hints, while complying with the observational limits on axion couplings. We identify the most favorable models, and the regions in the mass/couplings parameter space which are preferred by the global fit. Finally, we scrutinize the discovery potential for such models at upcoming helioscopes, namely IAXO and its scaled versions.

    hep-phastro-ph.HEastro-ph.SRJCAP(2022)·72 citations
22. 22*

    The role of the chiral anomaly in polarized deeply inelastic scattering II: Topological screening and transitions from emergent axion-like dynamics

    Andrey Tarasov🇺🇸 · Raju Venugopalan🇺🇸

    In [1], we demonstrated that the structure function $g_1(x_B,Q^2)$ measured in polarized deeply inelastic scattering (DIS) is dominated by the triangle anomaly in both the Bjorken limit of large $Q^2$ and the Regge limit of small $x_B$. In the worldline formulation of quantum field theory, the triangle anomaly arises from the imaginary part of the worldline effective action. We show explicitly how a Wess-Zumino-Witten term coupling the topological charge density to a primordial isosinglet $\bar{\eta }$ arises in this framework. We demonstrate the fundamental role played by this contribution both in topological mass generation of the ${\eta }^{\prime }$ and in the cancellation of the off-forward pole arising from the triangle anomaly in the proton's helicity $\Sigma (Q^2)$. We recover the striking result by Shore and Veneziano that $\Sigma \propto \sqrt{{\chi }^{\prime }(0)}$, where ${\chi }^{\prime }$ is the slope of the QCD topological susceptibility in the forward limit. We construct an axion-like effective action for $g_1$ at small $x_B$ that describes the interplay between gluon saturation and the topology of the QCD vacuum. In particular, we outline the role of "over-the-barrier" sphaleron-like transitions in spin diffusion at small $x_B$. Such topological transitions can be measured in polarized DIS at a future Electron-Ion Collider.

    hep-phhep-thnucl-thPRD(2022)·48 citations
23. 23*

    Higher-Order Kinematical Effects in Deeply Virtual Compton Scattering

    Yuxun Guo🇺🇸 · Xiangdong Ji🇺🇸 · Kyle Shiells🇺🇸

    We study the deeply virtual Compton scattering cross-section in twist-two generalized parton distribution (GPD) approximation, and show that different choices of light-cone vectors and gauges for the final photon polarization will lead to different higher-order kinematical corrections to the cross-section formula. The choice of light-cone vectors affects kinematic corrections at the twist-three level, accounting for the differences between the cross-section formulas in the literature. On the other hand, kinematical corrections from higher-twist GPDs should eliminate the light-cone dependence at twist three. Those light-cone dependencies are studied systematically at JLab 12 GeV and future EIC kinematics. They serve as the intrinsic systematic uncertainties in extracting the Compton form factors through the cross-section formula. More importantly, they are also necessary for understanding cross-section measurements with higher-twist precision and to reconstruct higher-order Compton form factors.

    hep-phnucl-exnucl-thJHEP(2021)·26 citations
24. 24*

    Mergers of Maximally Charged Primordial Black Holes

    Konstantinos Kritos🇺🇸 · Joseph Silk🇫🇷

    Near-extremal primordial black holes stable over cosmological timescales may constitute a significant fraction of the dark matter. Due to their charge the coalescence rate of such black holes is enhanced inside clusters and the non-extremal merger remnants are prone to Hawking evaporation. We demonstrate that if these clusters of near-extremal holes contain a sufficient number of members to survive up to low redshift, the hard photons from continued evaporation begin to dominate the high energy diffuse background. We find that the diffuse photon flux can be observed for a monochromatic mass spectrum of holes lighter than about $10^{12}\mathrm{g}$. We place upper bounds on their abundance respecting the current bounds set by gamma ray telescopes. Furthermore, the gravitational wave background induced at the epoch of primordial black hole formation may be detectable by future planned and proposed ground-based and space-borne gravitational wave observatories operating in the mHz to kHz frequency range and can be an important tool for studying light charged primordial black holes over masses in the range $10^{12}\mathrm{g}-10^{19}\mathrm{g}$.

    ↳ gr-qcastro-ph.COhep-phPRD(2022)·20 citations
25. 25*

    System Size and Flavour Dependence of Chemical Freeze-out Temperatures in ALICE Data from pp, pPb and PbPb Collisions at LHC Energies

    Fernando Antonio Flor🇺🇸 · Gabrielle Olinger🇺🇸 · René Bellwied🇺🇸

    We present the system size and flavour dependence of the chemical freeze-out temperature ($T_{\mathrm{ch}}$) at vanishing baryo-chemical potential calculated via thermal fits to experimental yields for several multiplicity classes in pp, pPb and PbPb collisions measured by ALICE. Using the Thermal-FIST Hadron Resonance Gas model package, we compare the quality of fits across various treatments of strangeness conservation under different freeze-out conditions as a function of the charged particle multiplicity density $⟨d{N}_{\mathrm{ch}}/d\eta ⟩$. Additionally, we examine how the anti-hadron to pion yield ratios of light and strange baryons, as well as the $\varphi$ meson, evolve within a flavour-dependent model. Through a unique two-temperature chemical freeze-out approach, we show that flavour dependence of $T_{\mathrm{ch}}$ in a Strangeness Canonical Ensemble leads to a natural explanation of strangeness enhancement from small to large systems at LHC energies without requiring any non-equilibrium particle production at small $⟨d{N}_{\mathrm{ch}}/d\eta ⟩$.

    ↳ nucl-exhep-exhep-phnucl-thPLB(2022)·23 citations
26. 26*

    The cosmic coincidences of primordial-black-hole dark matter

    Yi-Peng Wu🇫🇷 · Elena Pinetti🇫🇷 · Joseph Silk🇫🇷

    If primordial black holes (PBHs) contribute more than 10 percent of the dark matter (DM) density, their energy density today is of the same order as that of the baryons. Such a cosmic coincidence might hint at a mutual origin for the formation scenario of PBHs and the baryon asymmetry of the Universe. Baryogenesis can be triggered by a sharp transition of the rolling rate of inflaton from slow-roll to (nearly) ultraslow-roll phases that produces large curvature perturbations for PBH formation in single-field inflationary models. We show that the baryogenesis requirement drives the PBH contribution to DM, along with the inferred PBH mass range, the resulting stochastic gravitational wave background frequency window, and the associated cosmic microwave background tensor-to-scalar ratio amplitude, into potentially observable regimes.

    ↳ astro-ph.COhep-phPRL(2022)·17 citations
27. 27*

    General One-loop Reduction in Generalized Feynman Parametrization Form

    Hongbin Wang🇨🇳

    Recently there is an alternative reduction method proposed by Chen in [1,2]. In this paper, using the one-loop scalar integrals with propagators having higher power, we show the power of the improved version of Chen's new method in which we used some tricks to cancel the dimension shift and the terms we do not want. We present the explicit examples of bubble, triangle, box and pentagon with one propagators doubled. With these results, we have completed our previous computations in \cite{wang} with the missed tadpole coefficients.

    ↳ hep-thhep-phCPC(2022)·0 citations
28. 28*

    Lambda polarization in ${}^{108}$Ag +${}^{108}$Ag and ${}^{197}$Au +${}^{197}$Au collisions around a few GeV

    Xian-Gai Deng🇨🇳 · Xu-Guang Huang🇨🇳 · Yu-Gang Ma🇨🇳

    Within the framework of Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, we extract the global spin polarization of $\Lambda$ hyperon in ${}^{108}$Ag + ${}^{108}$Ag and ${}^{197}$Au + ${}^{197}$Au collisions at $\sqrt{s_{\mathrm{NN}}}=2.42-62.4$ GeV. We use two different approaches to calculate the $\Lambda$ polarization $P_y$: approach I is based on equilibrium assumption so that $P_y$ is determined by thermal vorticity and approach II assumes a proportional relation between $P_y$ and the system's angular momentum in $\Lambda$'s rest frame. We find that both approaches can describe the experimental data at low energies around a few GeV but only approach I describes well also higher-energy data. This suggests that at higher energies the relativistic effect plays an important role. After taking into such effect properly, the relativity-improved approach II can describe the higher-energy data as well.

    ↳ nucl-thhep-phnucl-exPLB(2022)·48 citations
29. 29*

    Quantum gravitational states of ultracold neutrons as a tool for probing of beyond-Riemann gravity

    A. N. Ivanov🇦🇹 · M. Wellenzohn🇦🇹 · H. Abele🇦🇹

    We analyze a possibility to probe beyond-Riemann gravity (BRG) contributions, introduced by Kostelecky and Li (see Phys. Rev. D 103, 024059 (2021) and Phys. Rev. D 104, 044054 (2021)) on the basis of the Effective Field Theory (EFT) by Kostelecky Phys. Rev. D 69, 105009 (2004). We carry out such an analysis by calculating the BRG contributions to the transition frequencies of the quantum gravitational states of ultracold neutrons (UCNs). These states are being used for a test of interactions beyond the Standard Model (SM) and General Relativity (GR) in the qBOUNCE experiments. We improve by order of magnitude some constraints obtained by Kostelecky and Li (2106.11293 [gr-qc]).

    ↳ gr-qchep-phhep-thnucl-exPLB(2021)·23 citations
30. 30*

    Unequal-mass mergers of dark matter haloes with rare and frequent self-interactions

    Moritz S. Fischer🇩🇪 · Marcus Brüggen🇩🇪 · Kai Schmidt-Hoberg🇩🇪 · Klaus Dolag🇩🇪 · Antonio Ragagnin🇮🇹 · Andrew Robertson🇬🇧

    Dark matter (DM) self-interactions have been proposed to solve problems on small length scales within the standard cold DM cosmology. Here, we investigate the effects of DM self-interactions in merging systems of galaxies and galaxy clusters with equal and unequal mass ratios. We perform N-body DM-only simulations of idealized setups to study the effects of DM self-interactions that are elastic and velocity-independent. We go beyond the commonly adopted assumption of large-angle (rare) DM scatterings, paying attention to the impact of small-angle (frequent) scatterings on astrophysical observables and related quantities. Specifically, we focus on DM-galaxy offsets, galaxy--galaxy distances, halo shapes, morphology, and the phase--space distribution. Moreover, we compare two methods to identify peaks: one based on the gravitational potential and one based on isodensity contours. We find that the results are sensitive to the peak finding method, which poses a challenge for the analysis of merging systems in simulations and observations, especially for minor mergers. Large DM-galaxy offsets can occur in minor mergers, especially with frequent self-interactions. The subhalo tends to dissolve quickly for these cases. While clusters in late merger phases lead to potentially large differences between rare and frequent scatterings, we believe that these differences are non-trivial to extract from observations. We therefore study the galaxy/star populations which remain distinct even after the DM haloes have coalesced. We find that these collisionless tracers behave differently for rare and frequent scatterings, potentially giving a handle to learn about the micro-physics of DM.

    ↳ astro-ph.COastro-ph.GAhep-phMNRAS(2022)·28 citations
31. 31*

    Skyrmions and Fractional Quantum Hall Droplets Unified by Hidden Symmetries in Dense Matter

    Mannque Rho🇫🇷

    A chain of connections in compressed baryonic matter, up-to-date glaringly missing in nuclear effective field theory, between intrinsic or emergent symmetries of QCD, mesons-gluons dualities, vector meson dominance and Chern-Simons fields has recently been revealed, presaging a possible new paradigm in nuclear theory. It indicates a ubiquitous role, thus far unexplored, of hidden symmetries -- flavor-local and scale -- permeating from dilute baryonic systems to normal nuclear matter and then to compact-star matter. Here I give a brief account of the possibly "indispensable" relevance of the ${\eta }^{\prime }$ singular ring, a.k.a. fractional quantum Hall (FQH) droplet, to the properties of the lowest-lying vector mesons $\omega$ and $\rho$, relevant to dilepton production processes, argued to be Seiberg-dual to the gluons near the chiral restoration.

    ↳ nucl-thhep-ph2 citations
32. 32*

    Axions from Neutron Star Mergers

    Damiano F. G. Fiorillo🇮🇹 · Fabio Iocco🇮🇹

    Axion-like particles (ALP) can in principle be produced in very hot and dense astrophysical environments, escape from the extreme object where such conditions are met, and then be converted in gamma--rays in the magnetic fields intervening between the event and the Earth. This process potentially offers a new window on both the physics of the axions, and the inner working of the astrophysical objects where they are produced. Interestingly, while this process has been studied for core--collapse supernovae and other extreme astrophysical events, no estimate exists for Neutron Star Mergers, objects recently identified through the detection of gravitational waves. In this work we study the production of ALPs in neutron star mergers, finding that for a large region of the ALP parameter space its magnitude at the source is such to produce a sizable gamma-ray signal at Earth. We show detection forecasts for such events placed in nearby galaxies, finding that they are potentially observable with the Fermi--LAT, thus opening a new window into both the astrophysics of these cataclysmic events, and of new particles beyond the standard model.

    ↳ astro-ph.HEhep-phPRD(2022)·3 citations
33. 33*

    Pole inflation from non-minimal coupling to gravity

    Sotirios Karamitsos🇮🇹 · Alessandro Strumia🇮🇹

    Transforming canonical scalars to the Einstein frame can give a multi-field generalization of pole inflation (namely, a scalar with a divergent kinetic term) at vanishing field-dependent Planck mass. However, to obtain an attractor, the scalar potential must obey certain non-generic conditions. These are automatically satisfied in Quantum Field Theories with dimension-less couplings. The resulting models of pole inflation have special inflationary predictions determined by the full RG running of couplings. Acceptable predictions for the tensor/scalar ratio arise for perturbative but moderately large couplings, so we explore the possible QFT runnings: to confinement, to an IR fixed point, and to a UV fixed point.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2022)·10 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.