Tue·Feb 9, 2021Tuesday·February 9, 2021

1. 01*

   Searching for Physics Beyond the Standard Model in an Off-Axis DUNE Near Detector

   Moritz Breitbach🇩🇪 · Luca Buonocore🇨🇭 · Claudia Frugiuele🇮🇹 · Joachim Kopp🇨🇭 · Lukas Mittnacht🇩🇪

   Next generation neutrino oscillation experiments like DUNE and T2HK are multi-purpose observatories, with a rich physics program beyond oscillation measurements. A special role is played by their near detector facilities, which are particularly well-suited to search for weakly coupled dark sector particles produced in the primary target. In this paper, we demonstrate this by estimating the sensitivity of the DUNE near detectors to the scattering of sub-GeV DM particles and to the decay of sub-GeV sterile neutrinos ("heavy neutral leptons"). We discuss in particular the importance of the DUNE-PRISM design, which allows some of the near detectors to be moved away from the beam axis. At such off-axis locations, the signal-to-background ratio improves for many new physics searches. We find that this leads to a dramatic boost in the sensitivity to boosted DM particles interacting mainly with hadrons, while for boosted DM interacting with leptons, data taken on-axis leads to marginally stronger exclusion limits. Searches for heavy neutral leptons perform equally well in both configurations.

   hep-phhep-exJHEP(2022)·66 citations
2. 02*

   Radiative corrections to nucleon weak charges and Beyond Standard Model impact

   Leendert Hayen🇺🇸

   The nucleon axial charge is a central ingredient in nuclear and particle physics, and a key observable in precision tests of the electroweak Standard Model sector and beyond. We report on the first complete calculation of its electroweak quantum corrections up to $\mathcal{O}(\alpha )$, using a combination of current algebra techniques and QCD sum rules. We find a substantial enhancement due to the weak magnetism contribution in the elastic channel, and include higher-twist and target mass corrections at low $Q^2$ to find ${\Delta }_R^A=0.02881(22)$. Using analogous methods, we determine a new value for the vector charge renormalization, ${\Delta }_R^V=0.02474(27)$, and show how the two most recent calculations can be brought into agreement. This allows us to determine a corrected experimental $g_A^0=1.2730(13)$, which is a $>2\sigma$ shift away from the commonly quoted value. We use this new result to set constraints on exotic right-handed currents by comparing to lattice QCD results, and resolve a double-counting issue in the $|V_{ud}|$ extraction from mirror decays.

   hep-phnucl-exnucl-th11 citations
3. 03*

   Fermion propagator in a rotating environment

   Alejandro Ayala🇲🇽 · L. A. Hernández🇿🇦 · K. Raya🇨🇳 · R. Zamora🇨🇱

   We apply the exponential operator method to derive the propagator for a fermion immersed within a rigidly rotating environment with cylindrical geometry. Given that the rotation axis provides a preferred direction, Lorentz symmetry is lost and the general solution is not translationally invariant in the radial coordinate. However, under the approximation that the fermion is completely dragged by the vortical motion, valid for large angular velocities, translation invariance is recovered. The propagator can then be written in momentum space. The result is suited to be used applying ordinary Feynman rules for perturbative calculations in momentum space.

   hep-phhep-thnucl-thPRD(2021)·23 citations
4. 04*

   Effective field theory approach to lepton number violating $\tau$ decays

   Yi Liao🇨🇳 · Xiao-Dong Ma🇹🇼 · Hao-Lin Wang🇨🇳

   We continue our endeavor to investigate lepton number violating (LNV) processes at low energy in the framework of effective field theory (EFT). In this work we study the LNV tau decays ${\tau }^{+}\to {\ell }^{-}{P}_i^{+}{P}_j^{+}$, where $\ell =e,\mu$ and $P_{i,j}^{+}$ are the lowest-lying charged pseudoscalars ${\pi }^{+},K^{+}$. We analyze the dominant contributions in a series of EFTs from high to low energy scales, namely, the standard model effective field theory (SMEFT), the low-energy effective field theory (LEFT), and the chiral perturbation theory ($\chi$PT). The decay branching ratios are expressed in terms of the Wilson coefficients of dimension-five and -seven operators in SMEFT and hadronic low energy constants. These Wilson coefficients involve the first and second generations of quarks and all generations of leptons and thus cannot be explored in low energy processes such as nuclear neutrinoless double decay or LNV kaon decays. Unfortunately, the current experimental upper limits on the branching ratios are too weak to set useful constraints on those coefficients. Or, if we assume the new physics scale is larger than 1 TeV, the branching ratios are well below the current experimental bounds. We also estimate hadronic uncertainties incurred in applying $\chi$PT to $\tau$ decays by computing one-loop chiral logarithms and attempt to improve convergence of chiral perturbation by employing dispersion relations in the short-distance part of the decay amplitudes.

   hep-phCPC(2021)·20 citations
5. 05*

   Study of $C$ parity violating and strangeness changing $J/\psi$ $\to$ $PP$ weak decays

   Yueling Yang🇨🇳 · Junliang Lu🇨🇳 · Mingfei Duan🇨🇳 · Jinshu Huang🇨🇳 · Junfeng Sun🇨🇳

   The $J/\psi$ weak decays are rare but possible within the standard model of elementary particles. Inspired by the potential prospects at the future intensity frontier, the $C$ parity violating $J/\psi$ $\to$ $\pi {\eta }^{(\prime )}$, $\eta {\eta }^{\prime }$ decays and the strangeness changing $J/\psi$ $\to$ $\pi K$, $K{\eta }^{(\prime )}$ decays are studied with the perturbative QCD approach. It is found that the $J/\psi$ $\to$ $\eta {\eta }^{\prime }$ decays have relatively large branching ratios, about the order of $10^{-11}$, which might be within the measurement capability and sensitivity of the future STCF experiment.

   hep-phhep-exCPC(2021)·0 citations
6. 06*

   Cwebs beyond three loops in multiparton amplitudes

   Neelima Agarwal · Lorenzo Magnea🇨🇭 · Sourav Pal🇮🇳 · Anurag Tripathi🇮🇳

   Correlators of Wilson-line operators in non-abelian gauge theories are known to exponentiate, and their logarithms can be organised in terms of collections of Feynman diagrams called webs. In [1] we introduced the concept of Cweb, or correlator web, which is a set of skeleton diagrams built with connected gluon correlators, and we computed the mixing matrices for all Cwebs connecting four or five Wilson lines at four loops. Here we complete the evaluation of four-loop mixing matrices, presenting the results for all Cwebs connecting two and three Wilson lines. We observe that the conjuctured column sum rule is obeyed by all the mixing matrices that appear at four-loops. We also show how low-dimensional mixing matrices can be uniquely determined from their known combinatorial properties, and provide some all-order results for selected classes of mixing matrices. Our results complete the required colour building blocks for the calculation of the soft anomalous dimension matrix at four-loop order.

   hep-phhep-thJHEP(2021)·22 citations
7. 07*

   The study of neutral triple gauge couplings in the process $e^{+}{e}^{-}\to Z\gamma$ including unitarity bounds

   Qing Fu🇨🇳 · Ji-Chong Yang🇨🇳 · Chong-Xing Yue🇨🇳 · Yu-Chen Guo🇨🇳

   The neutral triple gauge couplings~(nTGCs) provide a unique opportunity to probe new physics beyond the Standard Model. The nTGCs can be described by an effective field theory~(EFT), which is valid only under a certain energy scale. One of the signatures that an EFT is no longer valid is the violation of unitarity. We study the partial wave unitarity bounds on the coefficients of nTGCs in the process $e^{+}{e}^{-}\to Z\gamma$. In the experiments, the constraints obtained should be tighter than the unitarity bounds, otherwise the results are meaningless, therefore there exists a minimal luminosity for a $e^{+}{e}^{-}$ collider such as the CEPC to study the nTGCs. To derive the minimal luminosity, the kinematic features and event selection strategy are studied by Monte-Carlo simulation. Both the processes $e^{+}{e}^{-}\to {\ell }^{+}{\ell }^{-}\gamma$ and $e^{+}{e}^{-}\to jj\gamma$ are studied, event selection strategies are discussed. Based on the statistical significance, the expected constraints in experiments are estimated. The required luminosities for the experiments to reach the unitarity bounds are presented.

   hep-phNPB(2021)·30 citations
8. 08*

   Flavored axion in the UV-complete Froggatt-Nielsen models

   Leon M.G. de la Vega🇲🇽 · Newton Nath🇲🇽 · Stefan Nellen🇲🇽 · Eduardo Peinado🇲🇽

   We propose UV-completions of Froggatt-Nielsen-Peccei-Quinn models of fermion masses and mixings with flavored axions, by incorporating heavy fields. Here, the $U(1)$ Froggatt-Nielsen symmetry is identified with the Peccei-Quinn symmetry to solve the strong CP problem along with the mass hierarchies of the Standard Model fermions. We take into account leading order contributions to the fermion mass matrices giving rise to Nearest-Neighbour-Interaction structure in the quark sector and $A_2$ texture in the neutrino sector. A comprehensive numerical analysis has been performed for the fermion mass matrices. Subsequently, we investigate the resulting axion flavor violating couplings and the axion-photon coupling arising from the model.

   hep-phEPJC(2021)·22 citations
9. 09*

   High Energy Behaviour of Light Meson Photoproduction

   Moskov J. Amaryan (ODU)🇺🇸 · William J. Briscoe (GWU)🇺🇸 · Michael G. Ryskin (PNPI)🇷🇺 · Igor I. Strakovsky (GWU)🇺🇸

   We evaluated recent CLAS Collaboration measurements for the $90^{\circ }$ meson photoproduction off the nucleon using a tagged photon beam spanning the energy interval $s=3-11$ GeV${}^2$. The results are compared with the "Quark Counting Rules" predictions.

   hep-phhep-exnucl-exnucl-thPRC(2021)·6 citations
10. 10*

    The Bactrian Effect: Multiple Resonances and Light Dirac Dark Matter

    Thomas G. Rizzo🇺🇸

    The possibility of light dark matter (DM) annihilating through a dark photon (DP) which kinetically mixes (KM) with the Standard Model (SM) hypercharge field is a very attractive scenario. For DM in the interesting mass range below $\sim 1$ GeV, it is well known that bounds from the CMB provide a very strong model building constraint forcing the DM annihilation cross section to be roughly 3 orders of magnitude below that needed to reproduce the observed relic density. Under most circumstances this removes the possibility of an $s$-wave annihilation process for DM in this mass range as would be the case, e.g., if the DM were a Dirac fermion. In an extra-dimensional setup explored previously, it was found that the $s$-channel exchange of multiple gauge bosons could simultaneously encompass a suppressed annihilation cross section during the CMB era while also producing a sufficiently large annihilation rate during freeze-out to recover the DM relic density. In this paper, we analyze more globally the necessary requirements for this mechanism to work successfully and then realize them within the context of a simple model with two `dark' gauge bosons having masses of a similar magnitude and whose contributions to the annihilation amplitude destructively interfere. We show that if the DM mass threshold lies appropriately in the saddle region of this destructive interference between the two resonance humps it then becomes possible to satisfy these requirements simultaneously provided several ancillary conditions are met. The multiple constraints on the parameter space of this setup are then explored in detail to identify the phenomenologically successful regions.

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

    Towards establishing an abundant $B$ and $B_s$ spectrum up to the second orbital excitations

    Qi li🇨🇳 · Ru-Hui Ni🇨🇳 · Xian-Hui Zhong🇨🇳

    Stimulated by the exciting progress in experiments, we carry out a combined analysis of the masses, and strong and radiative decay properties of the $B$ and $B_s$-meson states up to the second orbital excitations. Based on our good descriptions of the mass and decay properties for the low-lying well-established states $B_1(5721)$, $B_2^{\ast }(5747)$, $B_{s1}(5830)$ and $B_{s2}^{\ast }(5840)$, we give a quark model classification for the high mass resonances observed in recent years. It is found that (i) the $B_J(5840)$ resonance may be explained as the low mass mixed state $B(|SD{⟩}_L)$ via $2^3{S}_1$-$1^3{D}_1$ mixing, or the pure $B(2^3{S}_1)$ state, or $B(2^1{S}_0)$. (ii) The $B_J(5970)$ resonance may be assigned as the $1^3{D}_3$ state in the $B$ meson family, although it as a pure $2^3{S}_1$ state cannot be excluded. (iii) The narrow structure around 6064 MeV observed in the $B^{+}{K}^{-}$ mass spectrum at LHCb may be mainly caused by the $B_{sJ}(6109)$ resonance decaying into $B^{\ast +}{K}^{-}$, and favors the assignment of the high mass $1D$-wave mixed state $B_s(1D_2^{\prime })$ with $J^P=2^{-}$, although it as the $1^3{D}_3$ state cannot be excluded. (iv) The relatively broader $B_{sJ}(6114)$ structure observed at LHCb may be explained with the mixed state $B_s(|SD{⟩}_H)$ via $2^3{S}_1$-$1^3{D}_1$ mixing, or a pure $1^3{D}_1$ state. Most of the missing $1P$-, $1D$-, and $2S$-wave $B$- and $B_s$-meson states have a relatively narrow width, they are most likely to be observed in their dominant decay channels with a larger data sample at LHCb.

    hep-phhep-exPRD(2021)·30 citations
12. 12*

    Search for a $D\bar{D}$ bound state in the ${\Lambda }_b\to \Lambda D\bar{D}$ process

    Le-Le Wei🇨🇳 · Hong-Shen Li🇨🇳 · En Wang🇨🇳 · Ju-Jun Xie🇨🇳 · De-Min Li🇨🇳 · Yu-Xiao Li🇨🇳

    We have investigated the process of ${\Lambda }_b\to \Lambda D\bar{D}$, by taking into account the contributions from the $s$-wave $D\bar{D}$ interaction within the coupled-channel unitary approach, and the intermediate $\psi (3770)$ resonance. In addition to the peak of the $\psi (3770)$, an enhancement near the $D\bar{D}$ mass threshold is found in the $D\bar{D}$ invariant mass distributions, which should be the reflection of the $D\bar{D}$ bound state. We would like to encourage our experimental colleagues to measure the $D\bar{D}$ invariant mass distribution of the ${\Lambda }_b\to \Lambda D\bar{D}$ process, which is crucial to search for the $D\bar{D}$ bound state and to understand the heavy-hadron heavy-hadron interactions.

    hep-phPRD(2021)·22 citations
13. 13*

    Electronic width of the $\psi (3770)$ resonance interfering with the background

    N.N. Achasov🇷🇺 · G.N. Shestakov🇷🇺

    Methods for extracting the $\psi (3770)\to e^{+}{e}^{-}$ decay width from the data on the reaction cross section $e^{+}{e}^{-}\to D\bar{D}$ are discussed. Attention is drawn to the absence of the generally accepted method for determining ${\Gamma }_{\psi (3770)e^{+}{e}^{-}}$ in the presence of interference between the contributions of the $\psi (3770)$ resonance and background. It is shown that the model for the experimentally measured $D$ meson form factor, which satisfies the requirement of the Watson theorem and takes into account the contribution of the complex of the mixed $\psi (3770)$ and $\psi (2S)$ resonances, allows uniquely determine the value of ${\Gamma }_{\psi (3770)e^{+}{e}^{-}}$ by fitting. The ${\Gamma }_{\psi (3770)e^{+}{e}^{-}}$ values found from the data processing are compared with the estimates in the potential models.

    hep-phhep-exnucl-thPRD(2021)·5 citations
14. 14*

    Relativistic corrections to decays of heavy baryons in the quark model

    Ahmad Jafar Arifi🇯🇵 · Daiki Suenaga🇯🇵 · Atsushi Hosaka🇯🇵

    We investigate relativistic corrections of order $1/m^2$, where $m$ is the constituent quark mass, to heavy baryon decays by emitting one pseudoscalar meson in the quark model. This work is motivated by shortcomings in the previous studies in the nonrelativistic quark model for decays of the Roper-like states such as ${\Lambda }_c(2765)$. We find that the relativistic corrections due to the internal motion of quarks are essential ingredients in improving their decay properties such that the decay widths are significantly increased. In addition, such corrections can explain a phenomenological suppression of the quark axial-vector coupling constant $g_A^q$ for the ${\Sigma }_c(2455)$ and ${\Sigma }_c(2520)$ decays.

    hep-phnucl-thPRD(2021)·36 citations
15. 15*

    Extended collinearly-improved Balitsky-Kovchegov evolution equation in target rapidity

    Wenchang Xiang🇨🇳 · Yanbing Cai🇨🇳 · Mengliang Wang🇨🇳 · Daicui Zhou🇨🇳

    An extended collinearly-improved Balitsky-Kovchegov evolution equation in the target rapidity representation is derived by including the running coupling corrections during the expansion of the "real" $S$-matrix. We find that the running coupling brings important corrections to the evolution equation, as one can see that there are extra contributions to the evolution kernel once the running coupling is included. To identify the significance of the corrections, we numerically solve the evolution equation with and without the running coupling contributions during the $S$-matrix expansion. The numerical results show that the scattering amplitude is largely suppressed by the running coupling corrections, which indicate that one needs to consider the running coupling contributions during the derivation of the non-linear evolution equation in the target rapidity representation.

    hep-phPRD(2021)·13 citations
16. 16*

    Strong Vertices of Doubly Heavy Spin-3/2 Baryons with Light Pseudoscalar Mesons

    A. R. Olamaei🇮🇷 · K. Azizi🇮🇷 · S. Rostami🇮🇷

    The strong coupling constants are basic quantities that carry information of the strong interactions among the baryon and meson multiplets as well as information on the natures and internal structures of the involved hadrons. These parameters enter to the transition matrix elements of various decays as main inputs and they play key roles in analyses of the experimental data including various hadrons. We determine the strong coupling constants among the doubly heavy spin-$3/2$ baryons, ${\Xi }_{Q{Q}^{\prime }}^{\ast }$ and ${\Omega }_{Q{Q}^{\prime }}^{\ast }$, and light pseudoscalar mesons, $\pi$, $K$ and $\eta$, using the light-cone QCD. The values obtained for the strong coupling constants under study may be used in construction of the strong potentials among the doubly heavy spin-3/2 baryons and light pseudoscalar mesons.

    hep-phhep-exhep-latCPC(2021)·8 citations
17. 17*

    An improved light-cone harmonic oscillator model for the pionic leading-twist distribution amplitude

    Tao Zhong🇨🇳 · Zhi-Hao Zhu🇨🇳 · Hai-Bing Fu🇨🇳 · Xing-Gang Wu🇨🇳 · Tao Huang🇨🇳

    In this paper, we study the pion leading-twist distribution amplitude ${\varphi }_{2;\pi }(x,\mu )$ by improving the traditional light-cone harmonic oscillator model within the reconstruction of the function ${\phi }_{2;\pi }(x)$. In order to constraining the model parameters, we calculate its moments $⟨{\xi }^n{⟩}_{2;\pi }{|}_{\mu }$ in the framework of QCD background field theory sum rule (BFTSR) up to $10^{\mathrm{th}}$ order. Considering the fact that the sum rule of the $0^{\mathrm{th}}$ moment $⟨{\xi }^0{⟩}_{2;\pi }{|}_{\mu }$ cannot be normalized, we suggest a more reasonable sum rule formula for $⟨{\xi }^n{⟩}_{2;\pi }{|}_{\mu }$. Then, we obtain the values of $⟨{\xi }^n{⟩}_{2;\pi }{|}_{{\mu }_0}$ with $n=(2,4,6,8,10)$ at the initial scale ${\mu }_0=1\mathrm{GeV}$. The first two moments are: $⟨{\xi }^2{⟩}_{2;\pi }{|}_{{\mu }_0}=0.271\pm 0.013$, $⟨{\xi }^4{⟩}_{2;\pi }{|}_{{\mu }_0}=0.138\pm 0.010$; and the corresponding Gegenbauer moments are $a_2^{2;\pi }({\mu }_0)=0.206\pm 0.038$, $a_4^{2;\pi }({\mu }_0)=0.047\pm 0.011$, respectively. After fitting the moments $⟨{\xi }^n{⟩}_{2;\pi }{|}_{\mu }$, we obtained the appropriate model parameters by using the least square method. The resultant behavior for twist-2 pion DA is more closely to the AdS/QCD and lattice result, but is narrower than that by Dyson-Schwinger equation. Furthermore, we calculate the pion-photon transition form factors (TFF) and $B\to \pi$ TFF within light-cone sum rule approach, which are conform with experimental and theoretical results.

    hep-phPRD(2021)·49 citations
18. 18*

    Leptonic CP and Flavor Violations in SUSY GUT with Right-handed Neutrinos

    Kaigo Hirao🇯🇵 · Takeo Moroi🇯🇵

    We study leptonic CP and flavor violations in supersymmetric (SUSY) grand unified theory (GUT) with right handed neutrinos, paying attention to the renormalization group effects on the slepton mass matrices due to the neutrino and GUT Yukawa interactions. In particular, we study in detail the impacts of the so-called Casas- Ibarra parameters on CP and flavor violating observables. The renormalization group effects induce CP and flavor violating elements of the SUSY breaking scalar mass squared matrices, which may result in sizable leptonic CP and flavor violating signals. Assuming seesaw formula for the active neutrino masses, the renormalization group effects have been often thought to be negligible as the right-handed neutrino masses become small. With the most general form of the neutrino Yukawa matrix, i.e., taking into account the Casas-Ibarra parameters, however, this is not the case. We found that the maximal possible sizes of signals of leptonic CP and flavor violating processes are found to be insensitive to the mass scale of the right-handed neutrinos and that they are as large as (or larger than) the present experimental bounds irrespective of the right-handed neutrino masses.

    hep-phPRD(2021)·7 citations
19. 19*

    Sensitivity of indirect detection of Neutralino dark matter by Sommerfeld enhancement mechanism

    Mikuru Nagayama🇯🇵 · Joe Sato🇯🇵 · Yasutaka Takanishi🇯🇵 · Kazuhiro Tsunemi🇯🇵

    We have investigated neutralino dark matter in the framework of minimal supersymmetric Standard Model focusing on the coannihilatioin region. In this region, where the particle whose mass is tightly degenerated with the neutralino dark matter exists, we can solve the Lithium problem in the case of lepton flavor being violated. It turns out that Sommerfeld enhancement is important in the coannihilation region so that the dark matter signal becomes large enough to be observed by the current sensitivity of indirect experiments.

    hep-phastro-ph.HEhep-ex0 citations
20. 20*

    On the interference of $ggH$ and $c\bar{c}H$ Higgs production mechanisms and the determination of charm Yukawa coupling at the LHC

    Wojciech Bizon🇩🇪 · Kirill Melnikov🇩🇪 · Jérémie Quarroz🇩🇪

    Higgs boson production in association with a charm-quark jet proceeds through two different mechanisms - one that involves the charm Yukawa coupling and the other that involves direct Higgs coupling to gluons. The interference of the two contributions requires a helicity flip and, therefore, cannot be computed with massless charm quarks. In this paper, we consider QCD corrections to the interference contribution starting from charm-gluon collisions with massive charm quarks and taking the massless limit, $m_c\to 0$. The behavior of QCD cross sections in that limit differs from expectations based on the canonical QCD factorization. This implies that QCD corrections to the interference term necessarily involve logarithms of the ratio $M_H/m_c$ whose resummation is currently unknown. Although the explicit next-to-leading order QCD computation does confirm the presence of up to two powers of $\ln (M_H/m_c)$ in the interference contribution, their overall impact on the magnitude of QCD corrections to the interference turns out to be moderate due to a cancellation between double and single logarithmic terms.

    hep-phJHEP(2021)·7 citations
21. 21*

    Solving the Hubble tension without spoiling Big Bang Nucleosynthesis

    Guo-yuan Huang🇩🇪 · Werner Rodejohann🇩🇪

    The Hubble parameter inferred from cosmic microwave background observations is consistently lower than that from local measurements, which could hint towards new physics. Solutions to the Hubble tension typically require a sizable amount of extra radiation $\Delta N_{\mathrm{eff}}^{}$ during recombination. However, the amount of $\Delta N_{\mathrm{eff}}^{}$ in the early Universe is unavoidably constrained by Big Bang Nucleosynthesis (BBN), which causes problems for such solutions. We present a possibility to evade this problem by introducing neutrino self-interactions via a simple Majoron-like coupling. The scalar is slightly heavier than $1\mathrm{MeV}$ and allowed to be fully thermalized throughout the BBN era. The rise of neutrino temperature due to the entropy transfer via $\varphi \to \nu \overline{\nu }$ reactions compensates the effect of a large $\Delta N_{\mathrm{eff}}^{}$ on BBN. Values of $\Delta N_{\mathrm{eff}}^{}$ as large as $0.7$ are in this case compatible with BBN. We perform a fit to the parameter space of the model.

    hep-phastro-ph.COPRD(2021)·46 citations
22. 22*

    Explicit Perturbations to the Stabilizer $\tau =\mathrm{i}$ of Modular $A_5^{\prime }$ Symmetry and Leptonic CP Violation

    Xin Wang🇨🇳 · Shun Zhou🇨🇳

    In a class of neutrino mass models with modular flavor symmetries, it has been observed that CP symmetry is preserved at the fixed point (or stabilizer) of the modulus parameter $\tau =\mathrm{i}$, whereas significant CP violation emerges within the neighbourhood of this stabilizer. In this paper, we first construct a viable model with the modular $A_5^{\prime }$ symmetry, and explore the phenomenological implications for lepton masses and flavor mixing. Then, we introduce explicit perturbations to the stabilizer at $\tau =\mathrm{i}$, and present both numerical and analytical results to understand why a small deviation from the stabilizer leads to large CP violation. As low-energy observables are very sensitive to the perturbations to model parameters, we further demonstrate that the renormalization-group running effects play an important role in confronting theoretical predictions at the high-energy scale with experimental measurements at the low-energy scale.

    hep-phJHEP(2021)·37 citations
23. 23*

    Testing new physics models with global comparisons to collider measurements: the Contur toolkit

    A. Buckley🇬🇧 · J. M. Butterworth🇬🇧 · L. Corpe🇬🇧 · M. Habedank🇩🇪 · D. Huang🇬🇧 · D. Yallup🇬🇧 · M. Altakach🇫🇷 · G. Bassman🇬🇧 · I. Lagwankar🇮🇳 · J. Rocamonde🇬🇧 · H. Saunders🇬🇧 · B. Waugh🇬🇧 · G. Zilgalvis🇬🇧

    Measurements at particle collider experiments, even if primarily aimed at understanding Standard Model processes, can have a high degree of model independence, and implicitly contain information about potential contributions from physics beyond the Standard Model. The Contur package allows users to benefit from the hundreds of measurements preserved in the Rivet library to test new models against the bank of LHC measurements to date. This method has proven to be very effective in several recent publications from the Contur team, but ultimately, for this approach to be successful, the authors believe that the Contur tool needs to be accessible to the wider high energy physics community. As such, this manual accompanies the first user-facing version: Contur v2. It describes the design choices that have been made, as well as detailing pitfalls and common issues to avoid. The authors hope that with the help of this documentation, external groups will be able to run their own Contur studies, for example when proposing a new model, or pitching a new search.

    hep-phSciPost Phys.Core(2021)·66 citations
24. 24*

    Heavy QCD Axion in $b\to s$ transition: Enhanced Limits and Projections

    Sabyasachi Chakraborty🇺🇸 · Manfred Kraus🇺🇸 · Vazha Loladze🇺🇸 · Takemichi Okui🇺🇸 · Kohsaku Tobioka🇺🇸

    We study a "heavy" QCD axion whose coupling to the standard model is dominated by $aG\tilde{G}$ but with $m_a\gg m_{\pi }{f}_{\pi }/f_a$. This is well motivated as it can solve the strong CP problem while evading the axion quality problem. It also poses interesting challenges for its experimental search due to its suppressed couplings to photons and leptons. Such axion with mass around a GeV is kinematically inaccessible or poorly constrained by most experimental probes except B-factories. We study $B\to Ka$ transitions as a powerful probe of the heavy QCD axion by performing necessary 2-loop calculations for the first time, together with some improvement on the existing analysis strategy. We find some of the existing limits are enhanced by at least an order of magnitude. We also demonstrate that the bounds are robust against unknown UV physics. For forthcoming data sets of the Belle II experiment, we provide a projection that $f_a$ of a few TeV is within its future reach, which is relevant to the quality problem.

    hep-phPRD(2021)·77 citations
25. 25*

    TeV cosmic ray nuclei acceleration in shell-type supernova remnants with hard $\gamma$-ray spectra

    Houdun Zeng🇨🇳 · Yuliang Xin🇨🇳 · Shuinai Zhang🇨🇳 · Siming Liu🇨🇳

    The emission mechanism for hard $\gamma$-ray spectra from supernova remnants (SNRs) is still a matter of debate. Recent multi-wavelength observations of TeV source HESS J1912+101 show that it is associated with an SNR with an age of $\sim 100$ kyrs, making it unlikely produce the TeV $\gamma$-ray emission via leptonic processes. We analyzed Fermi observations of it and found an extended source with a hard spectrum. HESS J1912+101 may represent a peculiar stage of SNR evolution that dominates the acceleration of TeV cosmic rays. By fitting the multi-wavelength spectra of 13 SNRs with hard GeV $\gamma$-ray spectra with simple emission models with a density ratio of GeV electrons to protons of $\sim 10^{-2}$, we obtain reasonable mean densities and magnetic fields with a total energy of $\sim 10^{50}$ ergs for relativistic ions in each SNR. Among these sources, only two of them, namely SN 1006 and RCW 86, favor a leptonic origin for the $\gamma$-ray emission. The magnetic field energy is found to be comparable to that of the accelerated relativistic ions and their ratio has a tendency of increase with the age of SNRs. These results suggest that TeV cosmic rays mainly originate from SNRs with hard $\gamma$-ray spectra.

    ↳ astro-ph.HEhep-phApJ(2021)·28 citations
26. 26*

    Critical behaviour of hydrodynamic series

    M. Asadi (1)🇮🇷 · H. Soltanpanahi (2 and 3)🇨🇳 · Farid Taghinavaz (1) ((1) IPM, Tehran, (2) South China Normal University, Guangzhou, (3) Jagiellonian University, Krakow)🇮🇷

    We investigate the time-dependent perturbations of strongly coupled $\mathcal{N}=4$ SYM theory at finite temperature and finite chemical potential with a second order phase transition. This theory is modelled by a top-down Einstein-Maxwell-dilaton description which is a consistent truncation of the dimensional reduction of type IIB string theory on AdS${}_5\times$S${}^5$. We focus on spin-1 and spin-2 sectors of perturbations and compute the linearized hydrodynamic transport coefficients up to the third order in gradient expansion. We also determine the radius of convergence of the hydrodynamic mode in spin-1 sector and the lowest non-hydrodynamic modes in spin-2 sector. Analytically, we find that all the hydrodynamic quantities have the same critical exponent near the critical point $\theta =1/2$. Moreover, we establish a relation between symmetry enhancement of the underlying theory and vanishing the only third order hydrodynamic transport coefficient ${\theta }_1$, which appears in the shear dispersion relation of a conformal theory on a flat background.

    ↳ hep-thcond-mat.str-elhep-phmath-ph+2JHEP(2021)·16 citations
27. 27*

    Non-gaussianities for primordial black hole formation

    Marco Taoso🇮🇹 · Alfredo Urbano🇮🇹

    We analyze primordial non-gaussianities in presence of an ultra-slow phase during the inflationary dynamics, focusing on scenarios relevant for the production of primordial black holes. We compute the three-point correlation function of comoving curvature perturbations finding that non-gaussianities are sizable, and predominantly local. In the context of threshold statistics, we analyze their impact for the abundance of primordial black holes, and their interplay with the non-gaussianities arising from the non-linear relation between density and curvature perturbations. We find that non-gaussianities significantly modify the estimate of the primordial black holes abundance obtained with the gaussian approximation. However, we show that this effect can be compensated by a small change, of a factor $2÷3$ at most, of the amplitude of the primordial power spectrum of curvature perturbations. This is obtained with a small tuning of the parameters of the inflationary model.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2021)·97 citations
28. 28*

    Condensation of Cooper Triples

    Sora Akagami🇯🇵 · Hiroyuki Tajima🇯🇵 · Kei Iida🇯🇵

    The condensation of Cooper pairs, originating from the Fermi-surface instability due to a weakly attractive interaction between two fermions, opened a new frontier for exploring many-body physics in interdisciplinary contexts. In this work, we discuss the possible condensation of Cooper triples, which are three-body counterparts of Cooper pairs for three-component fermions with a three-body attraction. Although each composite trimer-like state obeys the Fermi-Dirac statistics, its aggregate can form a condensate at zero center-of-mass momentum in the presence of the internal degrees of freedom associated with the relative momenta of constituent particles of momenta close to the Fermi surface. Such condensation can be regarded as bosonization in infinite-component fermions. We propose a variational wave function for the condensate of Cooper triples in analogy with the Bardeen-Cooper-Schrieffer ground state and obtain the ground-state energy.

    ↳ cond-mat.quant-gascond-mat.supr-conhep-phnucl-thPRA(2021)·16 citations
29. 29*

    Testing Fundamental Physics with Astrophysical Transients

    Jun-Jie Wei🇨🇳 · Xue-Feng Wu🇨🇳

    Explosive astrophysical transients at cosmological distances can be used to place precision tests of the basic assumptions of relativity theory, such as Lorentz invariance, the photon zero-mass hypothesis, and the weak equivalence principle (WEP). Signatures of Lorentz invariance violations (LIV) include vacuum dispersion and vacuum birefringence. Sensitive searches for LIV using astrophysical sources such as gamma-ray bursts, active galactic nuclei, and pulsars are discussed. The most direct consequence of a nonzero photon rest mass is a frequency dependence in the velocity of light propagating in vacuum. A detailed representation of how to obtain a combined severe limit on the photon mass using fast radio bursts at different redshifts through the dispersion method is presented. The accuracy of the WEP has been well tested based on the Shapiro time delay of astrophysical messengers traveling through a gravitational field. Some caveats of Shapiro delay tests are discussed. In this article, we review and update the status of astrophysical tests of fundamental physics.

    ↳ astro-ph.HEgr-qchep-phFront.Phys.(2021)·44 citations
30. 30*

    The axial charge of the triton from lattice QCD

    Assumpta Parreño🇪🇸 · Phiala E. Shanahan🇺🇸 · Michael L. Wagman🇺🇸 · Frank Winter🇺🇸 · Emmanuel Chang · William Detmold🇺🇸 · Marc Illa🇪🇸

    The axial charge of the triton is investigated using lattice quantum chromodynamics (QCD). Extending previous work at heavier quark masses, calculations are performed using three ensembles of gauge field configurations generated with quark masses corresponding to a pion mass of 450 MeV. Finite-volume energy levels for the triton, as well as for the deuteron and diproton systems, are extracted from analysis of correlation functions computed on these ensembles, and the corresponding energies are extrapolated to infinite volume using finite-volume pionless effective field theory (FVEFT). It is found with high likelihood that there is a compact bound state with the quantum numbers of the triton at these quark masses. The axial current matrix elements are computed using background field techniques on one of the ensembles and FVEFT is again used to determine the axial charge of the proton and triton. A simple quark mass extrapolation of these results and earlier calculations at heavier quark masses leads to a value of the ratio of the triton to proton axial charges at the physical quark masses of $g_A^{{}^3\mathrm{H}}/g_A^p=0.91\begin{array}{c}+0.07\\ -0.09\end{array}$. This result is consistent with the ratio determined from experiment and prefers values less than unity (in which case the triton axial charge would be unmodified from that of the proton), thereby demonstrating that QCD can explain the modification of the axial charge of the triton.

    ↳ hep-lathep-phnucl-thPRD(2021)·23 citations
31. 31*

    Bayesian Evidence for Both Astrophysical and Primordial Black Holes: Mapping the GWTC-2 Catalog to Third-Generation Detectors

    V. De Luca🇨🇭 · G. Franciolini🇨🇭 · P. Pani🇮🇹 · A. Riotto🇨🇭

    We perform a hierarchical Bayesian analysis of the GWTC-2 catalog to investigate the mixed scenario in which the merger events are explained by black holes of both astrophysical and primordial origin. For the astrophysical scenario we adopt the phenomenological model used by the LIGO/Virgo collaboration and we include the correlation between different parameters inferred from data, the role of the spins in both the primordial and astrophysical scenarios, and the impact of accretion in the primordial scenario. Our best-fit mixed model has a strong statistical evidence relative to the single-population astrophysical model, thus supporting the coexistence of populations of black-hole mergers of two different origins. In particular, our results indicate that the astrophysical mergers account for roughly four times the number of primordial black hole events and predict that third-generation detectors, such as the Einstein Telescope and Cosmic Explorer, should detect up to hundreds of mergers from primordial black hole binaries at redshift $z\gtrsim 30$.

    ↳ astro-ph.COgr-qchep-phJCAP(2021)·139 citations
32. 32*

    Prospects for Constraining Interacting Dark Energy Models with 21 cm Intensity Mapping Experiments

    Ming Zhang🇨🇳 · Bo Wang🇨🇳 · Peng-Ju Wu🇨🇳 · Jing-Zhao Qi🇨🇳 · Yidong Xu🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳

    We forecast constraints on cosmological parameters in the interacting dark energy models using the mock data generated for neutral hydrogen intensity mapping (IM) experiments. In this work, we only consider the interacting dark energy models with energy transfer rate $Q=\beta H{\rho }_{\mathrm{c}}$, and take BINGO, FAST, SKA1-MID, and Tianlai as typical examples of the 21 cm IM experiments. We find that the Tianlai cylinder array will play an important role in constraining the interacting dark energy model. Assuming perfect foreground removal and calibration, and using the Tianlai-alone data, we obtain $\sigma (H_0)=0.19$ km s${}^{-1}$ Mpc${}^{-1}$, $\sigma ({\Omega }_{\mathrm{m}})=0.0033$ and $\sigma ({\sigma }_8)=0.0033$ in the I$\Lambda$CDM model, which are much better than the results of Planck+optical BAO (i.e. optical galaxy surveys). However, the Tianlai-alone data cannot provide a very tight constraint on the coupling parameter $\beta$ compared with Planck+optical BAO, while the Planck+Tianlai data can give a rather tight constraint of $\sigma (\beta )=0.00023$ due to the parameter degeneracies being well broken by the data combination. In the I$w$CDM model, we obtain $\sigma (\beta )=0.00079$ and $\sigma (w)=0.013$ from Planck+Tianlai. In addition, we also make a detailed comparison among BINGO, FAST, SKA1-MID, and Tianlai in constraining the interacting dark energy models. We show that future 21 cm IM experiments will provide a useful tool for exploring the nature of dark energy and play a significant role in measuring the coupling between dark energy and dark matter.

    ↳ astro-ph.COgr-qchep-phApJ(2021)·51 citations
33. 33*

    Solving peak theory in the presence of local non-gaussianities

    Flavio Riccardi🇮🇹 · Marco Taoso🇮🇹 · Alfredo Urbano🇮🇹

    We compute the probability density distribution of maxima for a scalar random field in the presence of local non-gaussianities. The physics outcome of this analysis is the following. If we focus on maxima whose curvature is larger than a certain threshold for gravitational collapse, our calculations illustrate how the fraction of the Universe's mass in the form of primordial black holes (PBHs) changes in the presence of local non-gaussianities. We find that previous literature on the subject exponentially overestimate, by many orders of magnitude, the impact of local non-gaussianities on the PBH abundance. We explain the origin of this discrepancy, and conclude that, in realistic single-field inflationary models with ultra slow-roll, one can obtain the same abundance found with the gaussian approximation simply changing the peak amplitude of the curvature power spectrum by no more than a factor of two. We comment about the relevance of non-gaussianities for second-order gravitational waves.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2021)·50 citations
34. 34*

    Study of energy response and resolution of the ATLAS Tile Calorimeter to hadrons of energies from 16 to 30 GeV

    Jalal Abdallah🇺🇸 · Stylianos Angelidakis🇬🇷 · Giorgi Arabidze🇺🇸 · Nikolay Atanov🇷🇺 · Johannes Bernhard🇨🇭 · Romeo Bonnefoy🇫🇷 · Jonathan Bossio🇨🇦 · Ryan Bouabid🇺🇸 · Fernando Carrio🇪🇸 · Tomas Davidek🇨🇿 · Michal Dubovsky🇸🇰 · Luca Fiorini🇪🇸 and 59 other authors

    Three spare modules of the ATLAS Tile Calorimeter were exposed to test beams from the Super Proton Synchrotron accelerator at CERN in 2017. The measurements of the energy response and resolution of the detector to positive pions and kaons and protons with energy in the range 16 to 30 GeV are reported. The results have uncertainties of few percent. They were compared to the predictions of the Geant4-based simulation program used in ATLAS to estimate the response of the detector to proton-proton events at Large Hadron Collider. The determinations obtained using experimental and simulated data agree within the uncertainties.

    ↳ physics.ins-dethep-exhep-phEPJC(2021)·21 citations
35. 35*

    Perturbative unitarity in quasi-single field inflation

    Suro Kim🇯🇵 · Toshifumi Noumi🇯🇵 · Keito Takeuchi🇯🇵 · Siyi Zhou🇸🇪

    We study implications of perturbative unitarity for quasi-single field inflation with the inflaton and one massive scalar. Analyzing high energy scattering, we show that non-Gaussianities with $|f_{\mathrm{NL}}|\gtrsim 1$ cannot be realized without turning on interactions which violate unitarity at a high energy scale. Then, we provide a relation between $f_{\mathrm{NL}}$ and the scale of new physics that is required for UV completion. In particular we find that for the Hubble scale $H\gtrsim 6\times 10^9$ GeV, Planck suppressed operators can easily generate too large non-Gaussanities and so it is hard to realize successful quasi-single field inflation without introducing a mechanism to suppress quantum gravity corrections. Also we generalize the analysis to the regime where the isocurvature mode is heavy and the inflationary dynamics is captured by the inflaton effective theory. Requiring perturbative unitarity of the two-scalar UV models with the inflaton and one heavy scalar, we clarify the parameter space of the $P(X,\varphi )$ model which is UV completable by a single heavy scalar.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2021)·16 citations
36. 36*

    An Unbiased Estimator of the Full-sky CMB Angular Power Spectrum at Large Scales using Neural Networks

    Pallav Chanda🇮🇳 · Rajib Saha🇮🇳

    Accurate estimation of the Cosmic Microwave Background (CMB) angular power spectrum is enticing due to the prospect for precision cosmology it presents. Galactic foreground emissions, however, contaminate the CMB signal and need to be subtracted reliably in order to lessen systematic errors on the CMB temperature estimates. Typically bright foregrounds in a region lead to further uncertainty in temperature estimates in the area even after some foreground removal technique is performed and hence determining the underlying full-sky angular power spectrum poses a challenge. We explore the feasibility of utilizing artificial neural networks to predict the angular power spectrum of the full sky CMB temperature maps from the observed angular power spectrum of the partial sky in which CMB temperatures in some bright foreground regions are masked. We present our analysis at large angular scales with two different masks. We produce unbiased predictions of the full-sky angular power spectrum and recover the underlying theoretical power spectrum using neural networks. Our predictions are also uncorrelated to a large extent. We further show that the multipole-space covariances of the predictions of full-sky spectra made by the ANNs are much smaller than those of the estimates obtained using the pseudo-$C_{\ell }$ method.

    ↳ astro-ph.COcs.LGgr-qchep-ph+1MNRAS(2021)·8 citations
37. 37*

    Few-nucleon matrix elements in pionless effective field theory in a finite volume

    W. Detmold🇺🇸 · P. E. Shanahan🇺🇸

    Pionless effective field theory in a finite volume (FVEFT${}_{\pi /}$) is investigated as a framework for the analysis of multi-nucleon spectra and matrix elements calculated in lattice QCD (LQCD). By combining FVEFT${}_{\pi /}$ with the stochastic variational method, the spectra of nuclei with atomic number $A\in \{2,3\}$ are matched to existing finite-volume LQCD calculations at heavier-than-physical quark masses corresponding to a pion mass $m_{\pi }=806$ MeV, thereby enabling infinite-volume binding energies to be determined using infinite-volume variational calculations. Based on the variational wavefunctions that are constructed in this approach, the finite-volume matrix elements of various local operators are computed in FVEFT${}_{\pi /}$ and matched to LQCD calculations of the corresponding QCD operators in the same volume, thereby determining the relevant one and two-body EFT counterterms and enabling an extrapolation of the LQCD matrix elements to infinite volume. As examples, the scalar, tensor, and axial matrix elements are considered, as well as the magnetic moments and the isovector longitudinal momentum fraction.

    ↳ nucl-thhep-lathep-phPRD(2021)·35 citations
38. 38*

    Untangling scaling dimensions of fixed charge operators in Higgs Theories

    Oleg Antipin🇭🇷 · Jahmall Bersini🇭🇷 · Francesco Sannino🇩🇰 · Zhi-Wei Wang🇩🇰 · Chen Zhang🇹🇼

    We go beyond a systematic review of the semiclassical approaches for determining the scaling dimensions of fixed-charge operators in $U(1)$ and $O(N)$ models by introducing a general strategy apt at determining the relation between a given charge configuration and the associated operators for more involved symmetry groups such as the $U(N)\times U(M)$. We show how, varying the charge configuration, it is possible to access anomalous dimensions of different operators transforming according to a variety of irreducible representations of the non-abelian symmetry group without the aid of diagrammatical computations. We illustrate our computational strategy by determining the anomalous dimensions of several composite operators to the next-to-leading order in the semiclassical expansion for the $U(N)\times U(M)$ conformal field theory (CFT) in $4-ϵ$ dimensions. Thanks to the powerful interplay between semiclassical methods and group theory we can, for the first time, extract scaling dimensions for a wide range of operators.

    ↳ hep-thcond-mat.stat-mechhep-lathep-phPRD(2021)·25 citations
39. 39*

    High-Energy Neutrinos from Magnetized Coronae of Active Galactic Nuclei and Prospects for Identification of Seyfert Galaxies and Quasars in Neutrino Telescopes

    Ali Kheirandish🇺🇸 · Kohta Murase🇺🇸 · Shigeo S. Kimura🇯🇵

    Particles may be accelerated in magnetized coronae via magnetic reconnections and/or plasma turbulence, leading to high-energy neutrinos and soft gamma rays. We evaluate the detectability of neutrinos from nearby bright Seyfert galaxies identified by X-ray measurements. In the disk-corona model, we find that NGC 1068 is the most promising Seyfert galaxy in the Northern sky, where IceCube is the most sensitive, and show prospects for the identification of aggregated neutrino signals from Seyfert galaxies bright in X-rays. Moreover, we demonstrate that nearby Seyfert galaxies are promising targets for the next generation of neutrino telescopes such as KM3NeT and IceCube-Gen2. For KM3NeT, Cen A can be the most promising source in the Southern sky if a significant fraction of the observed X-rays come from the corona, and it could be identified in few years of KM3NeT operation. Our results reinforce the idea that hidden cores of supermassive black holes are the dominant sources of the high-energy neutrino emission and underlines the necessity of better sensitivity to medium-energy ranges in future neutrino detectors for identifying the origin of high-energy cosmic neutrinos.

    ↳ astro-ph.HEhep-phApJ(2021)·136 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.