Mon·Mar 15, 2021Monday·March 15, 2021

1. 01*

   The Benefits of Diligence: How Precise are Predicted Gravitational Wave Spectra in Models with Phase Transitions?

   Huai-Ke Guo🇺🇸 · Kuver Sinha🇺🇸 · Daniel Vagie🇺🇸 · Graham White🇯🇵

   Models of particle physics that feature phase transitions typically provide predictions for stochastic gravitational wave signals at future detectors and such predictions are used to delineate portions of the model parameter space that can be constrained. The question is: how precise are such predictions? Uncertainties enter in the calculation of the macroscopic thermal parameters and the dynamics of the phase transition itself. We calculate such uncertainties with increasing levels of sophistication in treating the phase transition dynamics. Currently, the highest level of diligence corresponds to careful treatments of the source lifetime; mean bubble separation; going beyond the bag model approximation in solving the hydrodynamics equations and explicitly calculating the fraction of energy in the fluid from these equations rather than using a fit; and including fits for the energy lost to vorticity modes and reheating effects. The lowest level of diligence incorporates none of these effects. We compute the percolation and nucleation temperatures, the mean bubble separation, the fluid velocity, and ultimately the gravitational wave spectrum corresponding to the level of highest diligence for three explicit examples: SMEFT, a dark sector Higgs model, and the real singlet-extended Standard Model (xSM). In each model, we contrast different levels of diligence in the calculation and find that the difference in the final predicted signal can be several orders of magnitude. Our results indicate that calculating the gravitational wave spectrum for particle physics models and deducing precise constraints on the parameter space of such models continues to remain very much a work in progress and warrants care.

   hep-phastro-ph.COJHEP(2021)·56 citations
2. 02*

   Resolving the Hubble tension in a U(1)${}_{L_{\mu }-L_{\tau }}$ model with Majoron

   Takeshi Araki🇯🇵 · Kento Asai🇯🇵 · Kei Honda🇯🇵 · Ryuta Kasuya🇯🇵 · Joe Sato🇯🇵 · Takashi Shimomura🇯🇵 · Masaki J.S. Yang🇯🇵

   In this paper, we explore possibilities of resolving the Hubble tension and $(g-2{)}_{\mu }$ anomaly simultaneously in a U(1)${}_{L_{\mu }-L_{\tau }}$ model with Majoron. We only focus on a case where the Majoron $\varphi$ does not exist at the beginning of the universe and is created by neutrino inverse decay $\nu \nu \to \varphi$ after electron-positron annihilation. In this case, contributions of the new gauge boson $Z^{\prime }$ and Majoron $\varphi$ to the effective number of neutrino species $N_{\mathrm{eff}}$ can be calculated in separate periods. These contribution are labelled $N_{\mathrm{eff}}^{\prime }$ for the U(1)${}_{L_{\mu }-L_{\tau }}$ gauge boson and $\Delta N_{\mathrm{eff}}^{\prime }$ for the Majoron. The effective number $N_{\mathrm{eff}}=N_{\mathrm{eff}}^{\prime }+\Delta N_{\mathrm{eff}}^{\prime }$ is evaluated by the evolution equations of the temperatures and the chemical potentials of light particles in each period. As a result, we found that the heavier $Z^{\prime }$ mass $m_{Z^{\prime }}$ results in the smaller $N_{\mathrm{eff}}^{\prime }$ and requires the larger $\Delta N_{\mathrm{eff}}^{\prime }$ to resolve the Hubble tension. Therefore, compared to previous studies, the parameter region where the Hubble tension can be resolved is slightly shifted toward the larger value of $m_{Z^{\prime }}$.

   hep-phPTEP(2021)·34 citations
3. 03*

   Broken Scaling Neutrino Mass Matrix and Leptogenesis based on A${}_4$ Modular invariance

   Monal Kashav🇮🇳 · Surender Verma🇮🇳

   In this work, we have proposed a modular $A_4$ symmetric model of neutrino mass which, simultaneously, explains observed baryon asymmetry of the Universe(BAU). In minimal extension of the standard model(SM) with two right-handed neutrinos we work in a supersymmetric framework. At Type-I seesaw level, the model predicts scaling in the neutrino mass matrix. In order to have correct low energy phenomenology, we propose two possible scenarios of scale-breaking in the neutrino mass matrix emanating from Type-I seesaw. Scenario-1 is based on the dimension-5 Weinberg operator whereas scenario-2 implements Type-II seesaw via scalar triplet Higgs superfields($\Delta ,\bar{\Delta }$). Interestingly, the breaking patterns in both, otherwise dynamically different scenarios, are similar which can be attributed to the same charge assignments of superfields($\Delta ,\bar{\Delta }$) and the Higgs superfield $H_u$ under modular $A_4$ symmetry. The breaking is found to be proportional to the Yukawa coupling of modular weight 10($Y_{1,1^{\prime }}^{10}$). We, further, investigates the predictions of the model under scenario-2 (Type-I+II) for neutrino mass, mixings and matter-antimatter asymmetry of the Universe. The model predicts normal hierarchical neutrino masses and provide a robust range ($0.05-0.08$)eV for sum of neutrino masses($\sum m_i$). Lepton number violating $0\nu \beta \beta$ decay amplitude($M_{ee}$) is obtained to lie in the range ($0.04-0.06$)eV. Future $0\nu \beta \beta$ decay experiments such as NEXT and nEXO shall pose crucial test for the model. Both $CP$ conserving and $CP$ violating solutions are allowed in the model. Interesting correlations are obtained, specially, between Yukawa couplings of modular weight 2 and complex modulus $\tau$. The model exhibit consistent explanation of BAU for right-handed Majorana neutrino mass scale in the range ($(1-5)\times 10^{13}$)GeV.

   hep-phJHEP(2021)·61 citations
4. 04*

   What is Leading Order for LFV in SMEFT?

   Marco Ardu🇫🇷 · Sacha Davidson🇫🇷

   Upcoming searches for lepton flavour change (LFV) aim to probe New Physics(NP) scales up to $\sim 10^4$ TeV, implying that they will be sensitive to NP at lower scales that is suppressed by loops or small couplings. We suppose that the NP responsable for LFV is beyond the reach of the LHC and can be parametrised in Effective Field Theory, introduce a small power-counting parameter à la Cabibbo-Wolfenstein, and assess whether the existing dimension six operator basis and one-loop RGEs provide a good approximation for LFV. We find that mu to e flavour-changing observables can be sensitive to a few dozen dimension eight operators, and to some effects of two-loop anomalous dimensions, for NP scales below 20-100 TeV. We also explore the effect of some simplifying assumptions in the one-loop RGEs, such as neglecting flavour-changing effects.

   hep-phJHEP(2021)·41 citations
5. 05*

   Performance of Monte Carlo event generators of pp collisions at NICA energies

   Maxim Azarkin🇷🇺 · Martin Kirakosyan🇷🇺

   This paper presents an overview of Monte Carlo(MC) event generators for simulation of proton-proton collisions along with the results on hadron production at Nuclotron-based Ion Collider fAcility (NICA) energies. Namely, mean multiplicities, mean transverse momenta, and rapidity distributions of p($\bar{\mathrm{p}}$), ${\pi }^{\pm }$, ${\mathrm{K}}^{\pm }$ at different collision energies are presented. We also study two-particle angular correlations for stable charged particles. Results of simulations with \pythia, \epos, and \urqmd event generators are compared to available data. Connections of studied quantities with physics mechanisms in MC generators are discussed. We suggest a tuned set of parameters to address observed discrepancies between data and \pythia.

   hep-phJ.Exp.Theor.Phys.(2023)·1 citation
6. 06*

   Magnetic moments of the spin-$\frac{3}{2}$ doubly charmed baryons in covariant baryon chiral perturbation theory

   Rui-Xiang Shi🇨🇳 · Li-Sheng Geng🇨🇳

   Inspired by the discovery of the spin-$\frac{1}{2}$ doubly charmed baryon ${\Xi }_{cc}^{++}$ and the subsequent theoretical studies of its magnetic moments, we study the magnetic moments of its spin-$\frac{3}{2}$ heavy quark spin symmetry counterparts, up to the next-to-leading order in covariant baryon chiral perturbation theory (BChPT) with the extended-on-mass-shell renormalization (EOMS) scheme. With the tree-level contributions fixed by the quark model while the two low energy constants (LECs) $C$ and $H$ controlling the loop contributions determined in two ways: the quark model (case 1) and lattice QCD simulations together with the quark model (case 2), we study the quark mass dependence of the magnetic moments and compare them with the predictions of the heavy baryon chiral perturbation theory (HB ChPT). It is shown that the difference is sizable in case 1, but not in case 2 due to the smaller LECs $C$ and $H$, similar to the case of spin-$\frac{1}{2}$ doubly charmed baryons. Second, we predict the magnetic moments of the spin-$\frac{3}{2}$ doubly charmed baryons and compare them with those of other approaches. The predicted magnetic moments in case 2 for the spin-$\frac{3}{2}$ doubly charmed baryons are closer to those of other approaches. In addition, the large differences in case 1 and case 2 for the predicted magnetic moments may indicate the inconsistency between the quark model and the lattice QCD simulations, which should be checked by future experimental or more lattice QCD data.

   hep-phhep-latPRD(2021)·17 citations
7. 07*

   Study on $Z_{cs}$ and excited $B_s^0$ states in the chiral quark model

   Xiaoyun Chen🇨🇳 · Yue Tan🇨🇳 · Yuan Chen🇨🇳

   Stimulated by the newly observed charged hidden-charm state $Z_{cs}(3985{)}^{-}$ by BESIII Collaboration, $Z_{cs}(4000{)}^{+}$, $Z_{cs}(4220{)}^{+}$ and the excited $B_s^0$ states by LHCb Collaboration, a full calculation including masses and decay widths is emerged in the chiral quark model. For $Z_{cs}$ states, we assign quantum numbers $I(J^P)=\frac{1}{2}(1^{+})$ and quark composition $c\bar{c}s\bar{u}$ according to the experiment. For $B_s^0$ states, systematically investigations are performed with $I(J^P)=0(0^{+}),0(1^{+}),0(2^{+})$ both in 2-body $b\bar{s}$ and 4-body $b\bar{s}q\bar{q}(q=u\mathrm{or}\mathrm{d})$ systems. Each tetraquark calculation takes all structures including meson-meson, diquark-antidiquark and all possible color configurations into account. Among the numerical techniques to solve the 2-body and 4-body Schrödinger equation, the spatial wave functions are expanded in series of Gaussian basis functions for high precision, which is the way Gaussian expansion method so called. Our results indicate that the low-lying states of 4-quark system are all higher than the corresponding thresholds either for $c\bar{c}s\bar{u}$ or for $b\bar{s}q\bar{q}$ systems. With the help of the real scaling method, we found two resonance states with masses of 4023 MeV and 4042 MeV for $c\bar{c}s\bar{u}$ system. The state $c\bar{c}s\bar{u}(4042)$ has a consistent mass and decay width with the recent observed state $Z_{cs}(3985{)}^{-}$. For $b\bar{s}q\bar{q}$ system with $J=0$, some resonance states are also found. The newly observed excited $B_s^0$ states can be accommodated in the chiral quark model as $2S$ or $1D$ states, and the mixing with four-quark states are also needed to be considered.

   hep-phPRD(2021)·14 citations
8. 08*

   Inclusive production of a heavy-light dijet system in hybrid high-energy and collinear factorization

   Andrèe Dafne Bolognino🇮🇹 · Francesco Giovanni Celiberto🇮🇹 · Michael Fucilla🇮🇹 · Dmitry Yu. Ivanov🇷🇺 · Alessandro Papa🇮🇹

   We propose the study of the inclusive hadroproduction of a heavy-flavored jet in association with a light jet, as a probe channel of strong interactions at high energies. We build up a hybrid factorization that encodes genuine high-energy effects, provided by a partial next-to-leading BFKL resummation, inside the standard collinear structure of the cross section. We present a detailed analysis of different distributions, shaped on kinematic ranges typical of experimental analyses at the Large Hadron Collider, and differential in rapidity, azimuthal angle and transverse momentum. The fair stability that these distributions exhibit under higher-order corrections motivates our interest toward future studies. Here, the hybrid factorization could help to deepen our understanding of heavy-flavor physics in wider kinematic ranges, like the ones accessible at the Electron-Ion Collider.

   hep-phPRD(2021)·83 citations
9. 09*

   Cold quark matter at N3LO: soft contributions

   Tyler Gorda🇩🇪 · Aleksi Kurkela🇳🇴 · Risto Paatelainen🇫🇮 · Saga Säppi🇮🇹 · Aleksi Vuorinen🇫🇮

   High-order perturbative calculations for thermodynamic quantities in QCD are complicated by the physics of dynamical screening that affects the soft, long-wavelength modes of the system. Here, we provide details for the evaluation of this soft contribution to the next-to-next-to-next-to-leading order (N3LO) pressure of high-density, zero-temperature quark matter (QM), complementing our accompanying paper in arXiv:2103.05658. Our calculation requires the determination of the pressure of the hard-thermal-loop (HTL) effective theory to full two-loop order at zero temperature, which we go through in considerable detail. In addition to this, we comprehensively discuss the structure of the weak-coupling expansion of the QM pressure, and lay out a roadmap towards the evaluation of the contributions missing from a full N3LO result for this quantity.

   hep-phnucl-thPRD(2021)·103 citations
10. 10*

    Singlet-assisted electroweak phase transition at two loops

    Lauri Niemi🇫🇮 · Philipp Schicho🇫🇮 · Tuomas V.I. Tenkanen🇸🇪

    We investigate the electroweak phase transition in the real-singlet extension of the Standard Model at two-loop level, building upon existing one-loop studies. We calculate the effective potential in the high-temperature approximation and detail the required resummations at two-loop order. In typical strong-transition scenarios, we find deviations of order $20\%-50\%$ from one-loop results in transition strength and critical temperature for both one- and two-step phase transitions. For extremely strong transitions, the discrepancy with one-loop predictions is even larger, presumably due to sizable scalar couplings in the tree-level potential. Along the way, we obtain a dimensionally-reduced effective theory applicable for non-perturbative lattice studies of the model.

    hep-phPRD(2021)·128 citations
11. 11*

    The forgotten channels: charged Higgs boson decays to a $W^{\pm }$ and a non-SM-like Higgs boson

    Henning Bahl🇩🇪 · Tim Stefaniak🇩🇪 · Jonas Wittbrodt🇸🇪

    The presence of charged Higgs bosons is a generic prediction of multiplet extensions of the Standard Model (SM) Higgs sector. Focusing on the Two-Higgs-Doublet-Model (2HDM), we discuss the charged Higgs boson collider phenomenology in the theoretically and experimentally viable parameter space. While almost all existing experimental searches at the LHC target the fermionic decays of charged Higgs bosons, we point out that the bosonic decay channels -- especially the decay into a non-SM-like Higgs boson and a $W$ boson -- often dominate over the fermionic channels. Moreover, we revisit two genuine BSM effects on the properties of the discovered Higgs boson -- the charged Higgs contribution to the diphoton rate and the Higgs decay to two light Higgs bosons -- and their implication for the charged Higgs boson phenomenology. As main result of the present paper, we propose five two-dimensional benchmark scenarios with distinct phenomenological features in order to facilitate the design of dedicated LHC searches for charged Higgs bosons decaying into a $W$ boson and a light, non-SM-like Higgs boson.

    hep-phhep-exJHEP(2021)·48 citations
12. 12*

    Mapping Gauged Q-Balls

    Julian Heeck🇺🇸 · Arvind Rajaraman🇺🇸 · Rebecca Riley🇺🇸 · Christopher B. Verhaaren🇺🇸

    Scalar field theories with particular U(1)-symmetric potentials contain non-topological soliton solutions called Q-balls. Promoting the U(1) to a gauge symmetry leads to the more complicated situation of gauged Q-balls. The soliton solutions to the resulting set of nonlinear differential equations have markedly different properties, such as a maximal possible size and charge. Despite these differences, we discover a relation that allows one to extract the properties of gauged Q-balls (such as the radius, charge, and energy) from the more easily obtained properties of global Q-balls. These results provide a new guide to understanding gauged Q-balls as well as providing simple and accurate analytical characterization of the Q-ball properties.

    ↳ hep-thhep-phPRD(2021)·38 citations
13. 13*

    Efficient sampling of constrained high-dimensional theoretical spaces with machine learning

    Jacob Hollingsworth🇺🇸 · Michael Ratz🇺🇸 · Philip Tanedo🇺🇸 · Daniel Whiteson🇺🇸

    Models of physics beyond the Standard Model often contain a large number of parameters. These form a high-dimensional space that is computationally intractable to fully explore. Experimental constraints project onto a subspace of viable parameters, but mapping these constraints to the underlying parameters is also typically intractable. Instead, physicists often resort to scanning small subsets of the full parameter space and testing for experimental consistency. We propose an alternative approach that uses generative models to significantly improve the computational efficiency of sampling high-dimensional parameter spaces. To demonstrate this, we sample the constrained and phenomenological Minimal Supersymmetric Standard Models subject to the requirement that the sampled points are consistent with the measured Higgs boson mass. Our method achieves orders of magnitude improvements in sampling efficiency compared to a brute force search.

    ↳ hep-thhep-phEPJC(2021)·26 citations
14. 14*

    First Lattice QCD determination of semileptonic decays of charmed-strange baryons ${\Xi }_c$

    Qi-An Zhang · Jun Hua · Fei Huang · Renbo Li · Yuanyuan Li · Cai-Dian Lu · Peng Sun · Wei Sun · Wei Wang · Yi-Bo Yang

    While the standard model is the most successfully theory to describe all interactions and constituents in elementary particle physics, it has been constantly examined for over four decades. Weak decays of charm quarks can measure the coupling strength of quarks in different families and serve as an ideal probe for CP violation. As the lowest charm-strange baryons with three different flavors, ${\Xi }_c$ baryons (made of $csu$ or $csd$) have been extensively studied in experiments at the large hadron collider and in electron-positron collision. However the lack of reliable knowledge in theory becomes the unavoidable obstacle in the way. In this work, we use the state-of-the-art Lattice QCD techniques, and generate 2+1 clover fermion ensembles with two lattice spacings, $a=(0.108\mathrm{fm},0.080\mathrm{fm})$. We then present the first {\it ab-initio} lattice QCD determination of form factors governing ${\Xi }_c\to \Xi {\ell }^{+}{\nu }_{\ell }$, analogous with the notable $\beta$-decay of nuclei. Our theoretical results for decay widths are consistent with and about two times more precise than the latest measurements by ALICE and Belle collaborations. Together with experimental measurements, we independently determine the quark-mixing matrix element $|V_{cs}|$, which is found in good agreement with other determinations.

    ↳ hep-lathep-exhep-phCPC(2022)·63 citations
15. 15*

    Majorana neutrino masses by D-brane instanton effects in magnetized orbifold models

    Kouki Hoshiya🇯🇵 · Shota Kikuchi🇯🇵 · Tatsuo Kobayashi🇯🇵 · Kaito Nasu🇯🇵 · Hikaru Uchida🇯🇵 · Shohei Uemura🇯🇵

    We study Majorana neutrino masses induced by D-brane instanton effects in magnetized orbifold models. We classify possible cases, where neutrino masses can be induced. Three and four generations are favored in order to generate neutrino masses by D-brane instantons. Explicit mass matrices have specific features. Their diagonalizing matrices correspond to the bimaximal mixing matrix in the case with even magnetic fluxes, independently of the modulus value $\tau$. On the other hand, for odd magnetic fluxes, diagonalizing matrices correspond nearly to the tri-bimaximal mixing matrix near $\tau =i$, while they become the bimaximal mixing matrix for larger $\mathrm{Im}\tau$. For even fluxes, neutrino masses are modular forms of the weight 1 on $T^2/{\mathbb{Z}}_2$, and they have symmetries such as $S_4^{\prime }$ and ${\Delta }^{\prime }(96)\times {\mathbb{Z}}_3$.

    ↳ hep-thhep-phPTEP(2022)·15 citations
16. 16*

    Rapid onset of the 21-cm signal suggests a preferred mass range for dark matter particle

    Venno Vipp🇪🇪 · Andi Hektor🇪🇪 · Gert Hütsi🇪🇪

    We are approaching a new era to probe the 21-cm neutral hydrogen signal from the period of cosmic dawn. This signal offers a unique window to the virgin Universe, e.g., to study dark matter models with different small-scale behaviours. The EDGES collaboration has recently published the first results of the global 21-cm spectrum. We demonstrate that such a signal can be used to set, unlike most observations concerning dark matter, both lower and upper limits for the mass of dark matter particles. We study the 21-cm signal resulting from a simple warm dark matter model with a sharp-$k$ window function calibrated for high redshifts. We tie the PopIII star formation to Lyman-alpha and radio background production. Using MCMC to sample the parameter space we find that to match the EDGES signal, a warm dark matter particle must have a mass of $7.3_{-3.3}^{+1.6}$ keV at 68\% confidence interval. This translates to $2.2_{-1.7}^{+1.4}\times 10^{-20}$ eV for fuzzy dark matter and $63_{-35}^{+19}$ keV for Dodelson-Widrow sterile neutrinos. Cold dark matter is unable to reproduce the signal due to its slow structure growth.

    ↳ astro-ph.COhep-phPRD(2021)·12 citations
17. 17*

    An Information Paradox and Its Resolution in de Sitter Holography

    Hao Geng🇺🇸 · Yasunori Nomura🇺🇸 · Hao-Yu Sun🇺🇸

    We formulate a version of the information paradox in de Sitter spacetime and show that it is solved by the emergence of entanglement islands in the context of the DS/dS correspondence; in particular, the entanglement entropy of a subregion obeys a time-dependent Page curve. Our construction works in general spacetime dimensions and keeps the graviton massless. We interpret the resulting behavior of the entanglement entropy using double holography. It suggests that the spatial distribution of microscopic degrees of freedom depends on descriptions, as in the case of a black hole. In the static (distant) description of de Sitter (black hole) spacetime, these degrees of freedom represent microstates associated with the Gibbons-Hawking (Bekenstein-Hawking) entropy and are localized toward the horizon. On the other hand, in a global (effective two-sided) description, which is obtained by the quantum analog of analytic continuation and is intrinsically semiclassical, they are distributed uniformly and in a unique semiclassical de Sitter (black hole) vacuum state.

    ↳ hep-thgr-qchep-phPRD(2021)·159 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.