Fri·Aug 27, 2021Friday·August 27, 2021

1. 01*

   Scalar leptoquark pair production at the LHC: precision predictions in the era of flavour anomalies

   Christoph Borschensky🇩🇪 · Benjamin Fuks🇫🇷 · Anna Kulesza🇩🇪 · Daniel Schwartländer🇩🇪

   We comprehensively examine precision predictions for scalar leptoquark pair production at the LHC. In particular, we investigate the impact of lepton $t$-channel exchange diagrams that are potentially relevant in the context of leptoquark scenarios providing an explanation for the flavour anomalies. We also evaluate the corresponding total rates at the next-to-leading order in QCD. Moreover, we complement this calculation with the resummation of soft-gluon radiation at the next-to-next-to-leading logarithmic accuracy, hence providing the most precise predictions for leptoquark pair production at the LHC to date. Relying on a variety of benchmark scenarios favoured by the anomalies, our results exhibit an interesting interplay between the $t$-channel diagram contributions, the flavour texture satisfied by the leptoquark Yukawa couplings, the leptoquark masses and their representations under the Standard Model gauge group, as well as the chosen set of parton densities used for the numerical evaluations. The net effect on a cross section turns out to be very non-generic and ranges up to about 60% with respect to the usual next-to-leading-order predictions in QCD (i.e. without any $t$-channel contribution) for some scenarios considered. Dedicated calculations are thus required for any individual leptoquark model that could be considered in a collider analysis in order to assess the size of the studied corrections. In order to facilitate such calculations we provide dedicated public numerical packages.

   hep-phhep-exJHEP(2022)·23 citations
2. 02*

   From the lineshape of the $X(3872)$ to its structure

   Angelo Esposito🇨🇭 · Luciano Maiani🇮🇹 · Alessandro Pilloni🇮🇹 · Antonio D. Polosa🇮🇹 · Veronica Riquer🇮🇹

   From a study of the lineshape of the $X(3872)$, the LHCb collaboration measures a sizeable negative effective range. This cannot be reconciled with a shallow $D{\bar{D}}^{\ast }$ bound state hypothesis. Based on Weinberg's compositeness criterion, together with a theorem by Smorodinsky, it follows that the $X$ has to have a compact hidden charm structure, most likely a tetraquark, interacting with unbound $D{\bar{D}}^{\ast }$ pairs via short-distance color forces. This conclusion is strengthened by the general pattern recently emerging for exotic mesons.

   hep-phnucl-thPRD(2022)·72 citations
3. 03*

   Valence quark ratio in the proton

   Zhu-Fang Cui🇨🇳 · Fei Gao🇩🇪 · Daniele Binosi🇮🇹 · Lei Chang🇨🇳 · Craig D. Roberts🇨🇳 · Sebastian M. Schmidt🇩🇪

   Beginning with precise data on the ratio of structure functions in deep inelastic scattering (DIS) from ${}^3$He and ${}^3$H, collected on the domain $0.19\le x_B\le 0.83$, where $x_B$ is the Bjorken scaling variable, we employ a robust method for extrapolating such data to arrive at a model-independent result for the $x_B=1$ value of the ratio of neutron and proton structure functions. Combining this with information obtained in analyses of DIS from nuclei, corrected for target-structure dependence, we arrive at a prediction for the proton's valence-quark ratio: ${d_v/u_v|}_{x_B\to 1}=0.230(57)$. Requiring consistency with this result presents a challenge to many descriptions of proton structure.

   hep-phhep-exhep-latnucl-ex+1Chin.Phys.Lett.(2022)·24 citations
4. 04*

   Near-threshold Spectrum from Uniformized Mittag-Leffler Expansion -Pole Structure of $Z(3900)$-

   Wren A. Yamada🇯🇵 · Osamu Morimatsu🇯🇵 · Toru Sato🇯🇵 · Koichi Yazaki🇯🇵

   We demonstrate how S-matrix poles manifest themselves as the physical spectrum near the upper threshold in the context of the two-channel uniformized Mittag-Leffler expansion, an expression written as a sum of pole terms under an appropriate variable where the S-matrix is made single-valued (uniformization). We show that the transition of the spectrum is continuous as a S-matrix pole moves across the boundaries of the complex energy Riemann sheets and that the physical spectrum peaks at or near the upper threshold when the S-matrix pole is positioned sufficiently close to it on the uniformized plane. There is no essential difference on which sheet the pole is positioned. What is important is the existence of a pole near the upper threshold and the distance between the pole and the physical region, not on which complex energy sheet the pole is positioned. We also point out that when the pole is close to the upper threshold, the complex pole does not have the usual meaning of the resonance. Neither the real part represents the peak energy, nor the imaginary part represents the half width. Subsequently, we try to understand the current status of $Z(3900)$ from the viewpoint of the uniformized Mittag-Leffler expansion reflecting in particular, Phys.Rev.Lett.117, 242001 (2016) in which they concluded that $Z(3900)$ is not a conventional resonance but a threshold cusp. We point out that their results turn out to indicate the existence of S-matrix poles near the $\bar{D}{D}^{\ast }$ threshold, which is most likely the origin of the peak found in their calculation of the near-threshold spectrum. In order to support our argument, we set up a separable potential model which shares common behavior of poles near the $\bar{D}{D}^{\ast }$ threshold to the above-mentioned reference and show in our model that the structures near the $\bar{D}{D}^{\ast }$ threshold are indeed caused by these near-threshold poles.

   hep-phnucl-thPRD(2022)·14 citations
5. 05*

   Deeply Learning Deep Inelastic Scattering Kinematics

   Markus Diefenthaler🇺🇸 · Abdullah Farhat🇺🇸 · Andrii Verbytskyi🇩🇪 · Yuesheng Xu🇺🇸

   We study the use of deep learning techniques to reconstruct the kinematics of the neutral current deep inelastic scattering (DIS) process in electron-proton collisions. In particular, we use simulated data from the ZEUS experiment at the HERA accelerator facility, and train deep neural networks to reconstruct the kinematic variables $Q^2$ and $x$. Our approach is based on the information used in the classical construction methods, the measurements of the scattered lepton, and the hadronic final state in the detector, but is enhanced through correlations and patterns revealed with the simulated data sets. We show that, with the appropriate selection of a training set, the neural networks sufficiently surpass all classical reconstruction methods on most of the kinematic range considered. Rapid access to large samples of simulated data and the ability of neural networks to effectively extract information from large data sets, both suggest that deep learning techniques to reconstruct DIS kinematics can serve as a rigorous method to combine and outperform the classical reconstruction methods.

   hep-phhep-exnucl-exEPJC(2022)·21 citations
6. 06*

   Higher-twist corrections to $D\to \pi ,K$ form factors from light-cone sum rules

   Long-Sheng Lu🇨🇳 · Yong-Kang Huang🇨🇳 · Xuan-Heng Zhang🇨🇳

   We calculate the $D\to P$ transition form factors within the framework of the light-cone QCD sum rules (LCSR) with the $D$-meson light-cone distribution amplitudes (LCDAs). The next-to-leading power (NLP) corrections to the vacuum-to-$D$-meson correlation function are considered, and the NLP corrections from the high-twist $D$-meson LCDAs and the SU(3) breaking effect from strange quark mass are investigated. Adopting the exponential model of the $D$-meson LCDAs,the predicted SU(3) flavor symmetry breaking effects are $R_{SU(3)}^{+,0}=1.12$ and $R_{SU(3)}^T=1.39$, respectively, which confirms the results from LCSR with pion LCDA. The numerical predictions of the form factors show that the contribution from two-particle higher-twist contributions is of great importance and the uncertainties are dominated by the inverse moment of ${\varphi }_D^{+}(\omega ,\mu )$. With the obtained form factors, the predicted Cabibbo-Kobayashi-Maskawa (CKM) matrix elements are $|V_{cd}|=0.151{}_{-0.043}^{+0.091}{|}_{th.}{}_{-0.02}^{+0.017}{|}_{exp.}$ and $|V_{cs}|=0.89{}_{-0.234}^{+0.467}{|}_{th.}{}_{-0.008}^{+0.008}{|}_{exp.}$.

   hep-phCPC(2021)·1 citation
7. 07*

   Non-unitary neutrino mixing in the NO$\nu$A near detector data

   Ushak Rahaman🇿🇦 · Soebur Razzaque🇿🇦

   The ${\nu }_{\mu }\to {\nu }_e$ oscillation probability over short baseline ($\lesssim 1$~km) would be negligible in case the mixing matrix for three active neutrinos is unitary. However, in case of non-unitary mixing of three neutrinos, this probability would be non-negligible due to the so-called "zero distance" effect. Hence, the near detector of the accelerator experiments such as NO$\nu$A can provide strong constraints on the parameters of the non-unitary mixing with very large statistics. By analyzing the NO$\nu$A near detector data we find that the non-unitary mixing does not improve fits to the ${\nu }_e$ or ${\nu }_{\mu }$ events over the standard unitary mixing. This leads to constraints on the non-unitary parameters: ${\alpha }_{00}>0.911$, $|{\alpha }_{10}|<0.020$ and ${\alpha }_{11}>0.952$ at 90\% C.L. A combined analysis with the near and far detector data does not change these constraints significantly.

   hep-phhep-exUniverse(2022)·7 citations
8. 08*

   Radiative corrections to decays of charged Higgs bosons in two Higgs doublet models

   Masashi Aiko🇯🇵 · Shinya Kanemura🇯🇵 · Kodai Sakurai🇯🇵

   We calculate the next-to-leading order (NLO) electroweak (EW) corrections to decay rates of charged Higgs bosons for various decay modes in the four types of two Higgs doublet models (THDMs) with the softly broken discrete Z_2 symmetry. Decay branching ratios of charged Higgs bosons are evaluated including NLO EW corrections, as well as QCD corrections up to next-to-next-to-leading order (NNLO). We comprehensively study impacts of the NLO EW corrections to the branching ratios in nearly alignment scenarios where the couplings constants of the Higgs boson with the mass of 125 GeV are close to those predicted in the standard model. Furthermore, in the nearly alignment scenario, we discuss whether or not the four types of THDMs can be distinguished via the decays of charged Higgs bosons. We find that characteristic predictions of charged Higgs branching ratios can be obtained for all types of the THDMs, by which each type of the THDMs are separated, and information on the internal parameters of the THDMs can be extracted from the magnitudes of the various decay branching ratios.

   hep-phNPB(2021)·18 citations
9. 09*

   Quantized electrical conductivity in binary neutron star mergers

   Sreemoyee Sarkar🇮🇳 · Souvik Priyam Adhya🇵🇱

   We examine nature of longitudinal electrical conductivity in magnetized electron-ion plasma in the context of binary neutron star mergers. In presence of strong magnetic field, high density and temperature, quantum oscillatory behaviour for electrons emerge due to breakdown of the classical description. For pronounced thermodynamic effects, we consider zeroth Landau level population of electrons for electrical conductivity. We solve Boltzmann equation in presence of magnetic field to obtain the dissipative component of the conductivity. The conductivity is formulated considering dynamically scattering centres in the medium with magnetically modified screening. Numerical estimations show that the effect of magnetically modified screening mass on electrical conductivity is less. On the other hand, we observe that frequency dependent screening reduces electrical conductivity leading to a reduction in the Ohmic decay time scale to become of the order of the characteristic timescale of the merger process in the low density regime. This indicates the relevance of dissipative process for the merger simulation in the above mentioned domain.

   hep-phastro-ph.HEnucl-thphysics.plasm-ph1 citation
10. 10*

    Discovering Axion-Like Particles with Photon Fusion at the ILC

    Noah Steinberg🇺🇸

    Experimental searches for Axion-Like Particles (ALPs) which couple to the electroweak bosons span over a wide range of ALP masses, from MeV searches at beam-dump experiments, to TeV searches at the LHC. Here we examine an interesting range of parameter space in which the ALP couples only to hypercharge. In the GeV to hundreds of GeV mass range, the contribution of an ALP to light by light scattering can be significant. By making simple kinematic cuts, we show that the ILC running at $\sqrt{s}=250\mathrm{GeV}$ or $\sqrt{s}=500\mathrm{GeV}$ can discover ALPs in this range of masses with significantly smaller couplings to the SM than previous experiments, down to $g_{aBB}=10^{-3}{\mathrm{TeV}}^{-1}$.

    hep-phhep-ex11 citations
11. 11*

    LFU and CP violation with $S_3$

    Nejc Košnik🇸🇮 · Aleks Smolkovič🇸🇮

    We introduce the CP violating scalar leptoquark $S_3$ to explain the measured values of the lepton universality ratios $R_{K^{(\ast )}}$. We derive constraints on the CP-even and CP-odd components of the leptoquark Yukawa couplings stemming from effects in $b\to s\mu \mu$ and $B_s$ mixing. For the $b\to s\mu \mu$ processes we impose $R_{K^{(\ast )}}$, $\mathcal{B}(B_s\to {\mu }^{+}{\mu }^{-})$, as well as CP-sensitive angular asymmetries $A_{7,8,9}$, whereas in the $B_s$ mixing sector $\Delta M_s$ and $S_{\psi \varphi }$ are considered. Combining the constraints within the $S_3$ model reveals that a large CP phase with a definite sign is perfectly viable for a leptoquark of mass below a few TeV. For larger mass of the $S_3$ leptoquark the CP phase is suppressed due to the observables pertaining to the $B_s$ system. We provide predictions of direct and mixing-induced CP asymmetries in $B\to K\mu \mu$ that could reveal the presence of the novel CP phase.

    hep-phhep-exPRD(2021)·8 citations
12. 12*

    Dark Matter Effective Theory

    Joachim Brod🇺🇸

    Les Houches 2021 lectures on dark matter effective field theory (short course). The aim of these two lectures is to calculate the DM-nucleus cross section for a simple example, and then generalize to the treatment of general effective interactions of spin-1/2 DM. Relativistic local operators, the heavy-DM effective theory, the chiral effective Lagrangian, and nuclear effective operators are briefly discussed.

    hep-phSciPost Phys.Lect.Notes(2022)·4 citations
13. 13*

    Energy-Dependent Neutrino Mixing Parameters at Oscillation Experiments

    K. S. Babu🇺🇸 · Vedran Brdar🇺🇸 · André de Gouvêa🇺🇸 · Pedro A. N. Machado🇺🇸

    Neutrino mixing parameters are subject to quantum corrections and hence are scale dependent. This means that the mixing parameters associated to the production and detection of neutrinos need not coincide since these processes are characterized by different energy scales. We show that, in the presence of relatively light new physics, the scale dependence of the mixing parameters can lead to observable consequences in long-baseline neutrino oscillation experiments, such as T2K and NOvA, and in neutrino telescopes like IceCube. We discuss some of the experimental signatures of this scenario, including zero-baseline flavor transitions, new sources of CP-invariance violation, and apparent inconsistencies among measurements of mixing angles at different experiments or oscillation channels. Finally, we present simple, ultraviolet-complete models of neutrino masses which lead to observable running of the neutrino mixing matrix below the weak scale.

    hep-phPRD(2022)·16 citations
14. 14*

    Remark on the QCD-electroweak phase transition in a supercooled Universe

    Dietrich Bodeker🇩🇪

    In extensions of the Standard Model with no dimensionful parameters the electroweak phase transition can be delayed to temperatures of order 100 MeV. Then the chiral phase transition of QCD can proceed with 6 massless quarks. The top-quark condensate destabilizes the Higgs potential through the Yukawa interaction, triggering the electroweak transition. Based on the symmetries of massless QCD, it has been argued that the chiral phase transition is first order. We point out that the top-Higgs Yukawa interaction is nonperturbatively large at the QCD scale, and that its effect on the chiral phase transition may not be negligible, violating some of the symmetries of massless QCD. The remaining symmetries indicate that top quarks condense in a second-order phase transition, but top condensation might also be triggered by a first-order symmetry-breaking transition in the light-quark sector.

    hep-phastro-ph.COPRD(2021)·11 citations
15. 15*

    Phenomenological study on correlation between flow harmonics and mean transverse momentum in nuclear collisions

    Chunjian Zhang🇺🇸 · Jiangyong Jia🇺🇸 · Shengli Huang🇺🇸

    To assess the properties of the quark-gluon plasma formed in nuclear collisions, the Pearson correlation coefficient between flow harmonics and mean transverse momentum, $\rho \left(v_n^2,\left[p_{\mathrm{T}}\right]\right)$, reflecting the overlapped geometry of colliding atomic nuclei, is measured. $\rho \left(v_2^2,\left[p_{\mathrm{T}}\right]\right)$ was found to be particularly sensitive to the quadrupole deformation of the nuclei. We study the influence of the nuclear quadrupole deformation on $\rho \left(v_n^2,\left[p_{\mathrm{T}}\right]\right)$ in $\mathrm{Au}+\mathrm{Au}$ and $\mathrm{U}+\mathrm{U}$ collisions at RHIC energy using $\mathrm{AMPT}$ transport model, and show that the $\rho \left(v_2^2,\left[p_{\mathrm{T}}\right]\right)$ is reduced by the prolate deformation ${\beta }_2$ and turns to change sign in ultra-central collisions (UCC).

    ↳ nucl-thhep-exhep-phSciPost Phys.Proc.(2022)·0 citations
16. 16*

    Rovibrational structure of the Ytterbium monohydroxide molecule and the $\mathcal{P}$,$\mathcal{T}$-violation searches

    Anna Zakharova🇷🇺 · Igor Kurchavov🇷🇺 · Alexander Petrov🇷🇺

    The spectrum of triatomic molecules with close rovibrational opposite parity levels is sensitive to the $\mathcal{P}$,$\mathcal{T}$-odd effects. This makes them a convenient platform for the experimental search of a new physics. Among the promising candidates one may distinguish the YbOH as a non-radioactive compound with a heavy atom. The energy gap between levels of opposite parity, $l$-doubling, is of a great interest as it determines the electric field strength required for the full polarization of the molecule. Likewise, the influence of the bending and stretching modes on the sensitivities to the $\mathcal{P}$,$\mathcal{T}$-violation requires a thorough investigation since the measurement would be performed on the excited vibrational states. This motivates us to obtain the rovibrational nuclear wavefunctions, taking into account the anharmonicity of the potential. As a result, we get the values of the $E_{\mathrm{eff}}$ and $E_s$ for the lowest excited vibrational state and determine the $l$-doubling

    ↳ physics.atom-phhep-phphysics.chem-phquant-phJ.Chem.Phys.(2021)·18 citations
17. 17*

    Learning to discover: expressive Gaussian mixture models for multi-dimensional simulation and parameter inference in the physical sciences

    Stephen B. Menary🇬🇧 · Darren D. Price🇬🇧

    We show that density models describing multiple observables with (i) hard boundaries and (ii) dependence on external parameters may be created using an auto-regressive Gaussian mixture model. The model is designed to capture how observable spectra are deformed by hypothesis variations, and is made more expressive by projecting data onto a configurable latent space. It may be used as a statistical model for scientific discovery in interpreting experimental observations, for example when constraining the parameters of a physical model or tuning simulation parameters according to calibration data. The model may also be sampled for use within a Monte Carlo simulation chain, or used to estimate likelihood ratios for event classification. The method is demonstrated on simulated high-energy particle physics data considering the anomalous electroweak production of a $Z$ boson in association with a dijet system at the Large Hadron Collider, and the accuracy of inference is tested using a realistic toy example. The developed methods are domain agnostic; they may be used within any field to perform simulation or inference where a dataset consisting of many real-valued observables has conditional dependence on external parameters.

    ↳ physics.data-ancs.LGhep-exhep-phMach.Learn.Sci.Tech.(2022)·1 citation
18. 18*

    Comparing meson-meson and diquark-antidiquark creation operators for a $\bar{b}\bar{b}ud$ tetraquark

    Marc Wagner🇩🇪 · Pedro Bicudo🇵🇹 · Antje Peters🇩🇪 · Sebastian Velten🇩🇪

    We compare two frequently discussed competing structures for a stable $\bar{b}\bar{b}ud$ tetraquark with quantum numbers $I(J^P)=0(1^{+})$ by considering a meson-meson as well as a diquark-antidiquark creation operator. We treat the heavy antiquarks as static with fixed positions and find diquark-antidiquark dominance for $\bar{b}\bar{b}$ separations $r<0.2\text{fm}$, while for $r>0.5\text{fm}$ the system essentially corresponds to a pair of $B$ mesons. For the meson-meson to diquark-antidiquark ratio of the tetraquark we obtain around $58\%/42\%$.

    ↳ hep-lathep-phPoS(2022)·3 citations
19. 19*

    Confronting the primordial black hole scenario with the gravitational-wave events detected by LIGO-Virgo

    Zu-Cheng Chen🇨🇳 · Chen Yuan🇨🇳 · Qing-Guo Huang🇨🇳

    Adopting a binned method, we model-independently reconstruct the mass function of primordial black holes (PBHs) from GWTC-3 and find that such a PBH mass function can be explained by a broad red-tilted power spectrum of curvature perturbations. Even though GW190521 with component masses in upper mass gap $(m>65M_{\odot })$ can be naturally interpreted in the PBH scenario, the events (including GW190814, GW190425, GW200105, and GW200115) with component masses in the light mass range $(m<3M_{\odot })$ are quite unlikely to be explained by binary PBHs although there are no electromagnetic counterparts because the corresponding PBH merger rates are much smaller than those given by LIGO-Virgo. Furthermore, we predict that both the gravitational-wave (GW) background generated by the binary PBHs and the scalar-induced GWs accompanying the formation of PBHs should be detected by the ground-based and space-borne GW detectors and pulsar timing arrays in the future.

    ↳ astro-ph.COgr-qchep-phhep-thPLB(2022)·83 citations
20. 20*

    Effect of density fluctuations on gravitational wave production in first-order phase transitions

    Ryusuke Jinno🇩🇪 · Thomas Konstandin🇩🇪 · Henrique Rubira🇩🇪 · Jorinde van de Vis🇩🇪

    We study the effect of density perturbations on the process of first-order phase transitions and gravitational wave production in the early Universe. We are mainly interested in how the distribution of nucleated bubbles is affected by fluctuations in the local temperature. We find that large-scale density fluctuations ($H_{\ast }<k_{\ast }<\beta$) result in a larger effective bubble size at the time of collision, enhancing the produced amplitude of gravitational waves. The amplitude of the density fluctuations necessary for this enhancement is ${\mathcal{P}}_{\zeta }(k_{\ast })\gtrsim (\beta /H_{\ast }{)}^{-2}$, and therefore the gravitational wave signal from first-order phase transitions with relatively large $\beta /H_{\ast }$ can be significantly enhanced by this mechanism even for fluctuations with moderate amplitudes.

    ↳ astro-ph.COhep-phJCAP(2021)·35 citations
21. 21*

    Dynamical Instability of Collapsed Dark Matter Halos

    Wei-Xiang Feng🇺🇸 · Hai-Bo Yu🇺🇸 · Yi-Ming Zhong🇺🇸

    A self-interacting dark matter halo can experience gravothermal collapse, resulting in a central core with an ultrahigh density. It can further contract and collapse into a black hole, a mechanism proposed to explain the origin of supermassive black holes. We study dynamical instability of the core in general relativity. We use a truncated Maxwell-Boltzmann distribution to model the dark matter distribution and solve the Tolman-Oppenheimer-Volkoff equation. For given model parameters, we obtain a series of equilibrium configurations and examine their dynamical instability based on considerations of total energy, binding energy, fractional binding energy, and adiabatic index. Our numerical results indicate that the core can collapse into a black hole when the fractional binding energy reaches $0.035$ with a central gravitational redshift of $0.5$. We further show for the instability to occur in the classical regime, the boundary temperature of the core should be at least $10\%$ of the mass of dark matter particles; for a $10^9{\mathrm{M}}_{\odot }$ seed black hole, the particle mass needs to be larger than a few keV. These results can be used to constrain different collapse models, in particular, those with dissipative dark matter interactions.

    ↳ astro-ph.COastro-ph.GAastro-ph.HEgr-qc+1JCAP(2022)·39 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.