Fri·Nov 1, 2019Friday·November 1, 2019

1. 01*

   Anomalous Magnetic Moments from Asymptotic Safety

   Gudrun Hiller🇩🇪 · Clara Hormigos-Feliu🇩🇪 · Daniel F. Litim🇬🇧 · Tom Steudtner🇬🇧

   The measurements of the muon and electron anomalous magnetic moments hint at physics beyond the standard model. We show why and how models inspired by asymptotic safety can explain deviations from standard model predictions naturally. Our setup features an enlarged scalar sector and Yukawa couplings between leptons and new vector-like fermions. Using the complete two-loop running of couplings, we observe a well-behaved high energy limit of models including a stabilization of the Higgs. We find that a manifest breaking of lepton universality beyond standard model Yukawas is not necessary to explain the muon and electron anomalies. We further predict the tau anomalous magnetic moment, and new particles in the TeV energy range whose signatures at colliders are indicated. With small CP phases, the electron EDM can be as large as the present bound.

   hep-phhep-thPRD(2020)·111 citations
2. 02*

   Twin Higgs with Exact $Z_2$

   Csaba Csáki🇺🇸 · Cong-Sen Guan🇺🇸 · Teng Ma🇮🇱 · Jing Shu🇨🇳

   We present a novel mechanism for realistic electroweak symmetry breaking in Twin Higgs/neutral naturalness models where the $Z_2$ exchange symmetry can remain exactly unbroken. The exchange symmetry in the Yukawa sector will be implemented as an "N-trigonometric parity" $\sin N\frac{h}{f}\leftrightarrow \cos N\frac{h}{f}$. The Yukawa couplings will be suppressed leading to an N-suppressed Higgs quadratic term, without significantly affecting the quartic. We present a concrete implementation of this idea for general (odd) values of N using maximal symmetry, and a realistic benchmark model for $N=3$. We find that the tuning in the resulting Higgs potential is negligible, and also show that two-loop N-suppression violating gauge contributions can be sufficiently small. The Higgs potential and its couplings in top sector are different from other neutral naturalness models, which are the main predictions of our model and can be tested in colliders.

   hep-phhep-thJHEP(2020)·20 citations
3. 03*

   A long-lived stop with freeze-in and freeze-out dark matter in the hidden sector

   Amin Aboubrahim🇺🇸 · Wan-Zhe Feng🇨🇳 · Pran Nath🇺🇸

   In extended supersymmetric models with a hidden sector the lightest $R$-parity odd particle can reside in the hidden sector and act as dark matter. We consider the case when the hidden sector has ultraweak interactions with the visible sector. An interesting phenomenon arises if the LSP of the visible sector is charged in which case it will decay to the hidden sector dark matter. Due to the ultraweak interactions, the LSP of the visible sector will be long-lived decaying outside the detector after leaving a track inside. We investigate this possibility in the framework of a $U(1{)}_X$-extended MSSM/SUGRA model with a small gauge kinetic mixing and mass mixing between the $U(1{)}_X$ and $U(1{)}_Y$ where $U(1{)}_Y$ is the gauge group of the hypercharge. Specifically we investigate the case when the LSP of MSSM is a stop which decays into the hidden sector dark matter and has a lifetime long enough to traverse the LHC detector without decay. It is shown that such a particle can be detected at the HL-LHC and HE-LHC as an $R$-hadron which will look like a slow moving muon with a large transverse momentum $p_T$ and so can be detected by the track it leaves in the inner tracker and in the muon spectrometer. Further, due to the ultraweak couplings between the hidden sector and the MSSM fields, the dark matter particle has a relic density arising from a combination of the freeze-out and freeze-in mechanisms. It is found that even for the ultraweak or feeble interactions the freeze-out contribution relative to freeze-in contribution to the relic density is substantial to dominant, varying between 30\% to 74\% for the model points considered. It is subdominant to freeze-in for relatively small stop masses with relatively larger stop annihilation cross-sections and the dominant contribution to the relic density for relatively large stop masses and relatively smaller stop annihilation cross-sections.

   hep-phhep-exJHEP(2020)·13 citations
4. 04*

   Axion Kinetic Misalignment Mechanism

   Raymond T. Co🇺🇸 · Lawrence J. Hall🇺🇸 · Keisuke Harigaya🇺🇸

   In the conventional misalignment mechanism, the axion field has a constant initial field value in the early universe and later begins to oscillate. We present an alternative scenario where the axion field has a nonzero initial velocity, allowing an axion decay constant much below the conventional prediction from axion dark matter. This axion velocity can be generated from explicit breaking of the axion shift symmetry in the early universe, which may occur as this symmetry is approximate.

   hep-phastro-ph.COPRL(2020)·300 citations
5. 05*

   Prediction of $N\Omega$-like dibaryons with heavy quarks

   Hongxia Huang🇨🇳 · Jialun Ping🇨🇳 · Fan Wang🇨🇳

   Possible $N\Omega$-like dibaryons $N{\Omega }_{ccc}$ and $N{\Omega }_{bbb}$ with quantum numbers $I{J}^P=\frac{1}{2}{2}^{+}$ are investigated within the framework of quark delocalization color screening model. We find both of these two states are bound, and the binding energy increases as the quarks of the system become heavier. The attraction between $N$ and ${\Omega }_{ccc}$ (or ${\Omega }_{bbb}$) mainly comes from the kinetic energy term due to quark delocalization and color screening. The effect of the channel-coupling provides more effective attraction to $N{\Omega }_{ccc}$ and $N{\Omega }_{bbb}$ systems. Besides, the scattering length, the effective range, and the binding energy, obtained from the calculation of the low-energy scattering phase shifts, also supports the existence of the $N{\Omega }_{ccc}$ and $N{\Omega }_{bbb}$ states. All these properties can provide necessary information for experimental search for the $N\Omega$-like dibaryons with heavy quarks. And the experimental progress can also check the mechanism of the intermediate-range attraction of the baryon-baryon interaction in quark models.

   hep-phnucl-thPRC(2020)·15 citations
6. 06*

   Probing QCD critical fluctuations from the yield ratio of strange hadrons in relativistic heavy-ion collisions

   Tianhao Shao🇨🇳 · Jinhui Chen🇨🇳 · Che Ming Ko🇺🇸 · Kai-Jia Sun🇺🇸

   By analyzing the available data on strange hadrons in central Pb+Pb collisions from the NA49 Collaboration at the Super Proton Synchrotron (SPS) and in central Au+Au collisions from the STAR Collaboration at the Relativistic Heavy-Ion Collider (RHIC) in a wide collision energy range from $\sqrt{s_{\mathrm{NN}}}$ = 6.3 GeV to 200 GeV, we find a possible non-monotonic behavior in the ratio \mathcal{O}_\text{K-\Xi$-$\phi$-$\Lambda}= $\frac{N(K^{+})N({\Xi }^{-})}{N(\varphi )N(\Lambda )}$ of $K^{+}$, ${\Xi }^{-}$, $\varphi$, and $\Lambda$ yields as a function of $\sqrt{s_{\mathrm{NN}}}$. Based on the quark coalescence model, which can take into account the effect of quark density fluctuations on hadron production, a possible non-monotonic behavior in the dependence of the strange quark density fluctuation on $\sqrt{s_{NN}}$ is obtained. This is in contrast to the coalescence model that does not include quark density fluctuations and also to the statistical hadronization model as both fail to describe even qualitatively the collision energy dependence of the ratio \mathcal{O}_\text{K-\Xi$-$\phi$-$\Lambda}. Our findings thus suggest that the signal and location of a possible critical endpoint in the QCD phase diagram, which is expected to result in large quark density fluctuations, can be found in the on-going Bean Energy Scan program at RHIC.

   hep-phnucl-exnucl-thPLB(2020)·15 citations
7. 07*

   Probing standard-model Higgs substructures using tops and weak gauge bosons

   Axel Maas🇦🇹 · Simon Fernbach🇦🇹 · Lukas Lechner🇦🇹 · Simon Plätzer🇦🇹 · Robert Schöfbeck🇦🇹 · Pascal Törek🇦🇹

   Manifest gauge-invariance requires that observable states in the standard-model are described by composite operators, which involve additional Higgs contributions beyond perturbation theory. This field-theoretical effect has been confirmed in lattice simulations. It should also be experimentally accessible at high enough precision. Here a few estimates for such signatures at current and future collider experiments will be discussed.

   hep-phPoS(2020)·1 citation
8. 08*

   Suppressing the Scattering of WIMP DM with Nucleons in Supersymmetric Theories

   Junjie Cao🇨🇳 · Lei Meng🇨🇳 · Yuanfang Yue🇨🇳 · Haijing Zhou🇨🇳 · Pengxuan Zhu🇨🇳

   The continuously improving sensitivity of dark matter direct detection experiments has limited the interaction between dark matter and nucleons being increasingly feeble, while the dark matter relic density favors it to take part in weak interactions. After taking into account the constraints from the Large Hadron Collider (LHC) search for Higgs bosons and sparticles, it is becoming difficult for the neutralino dark matter in the Minimal Supersymmetric Standard Model and the Next-to-Minimal Supersymmetric Standard Model to possess these two seemingly paradoxical features in their most natural parameter space for electroweak symmetry breaking due to the limited theoretical structure. In contrast, the seesaw extension of the Next-to-Minimal Supersymmetric Standard Model, which was initially proposed to solve the neutrino mass problem, enables the lightest sneutrino to act as a viable dark matter candidate, readily has these features, and thus, it easily satisfies the constraints from dark matter and LHC experiments. Compared with the Type-I seesaw extension, the dark matter physics in the inverse seesaw extension is more flexible, allowing it to be consistent with the experimental results in broader parameter space. We conclude that weakly interacting massive particles (such as the sneutrino in this study) work well in supersymmetric theories as dark matter candidates.

   hep-phPRD(2020)·39 citations
9. 09*

   Neutrino mass spectroscopy using Er${}^{3+}$ ions placed at inversion center of host crystals

   H. Hara🇯🇵 · N. Sasao🇯🇵 · A. Yoshimi🇯🇵 · M. Yoshimura🇯🇵

   We propose neutrino mass spectroscopy using Er${}^{3+}$:Cs${}_2$NaYF${}_6$ or :Y${}_2$O${}_3$ crystal placed in hollow of a Bragg fiber as a target system. Unknown neutrino parameters and properties such as the lightest neutrino mass, Majorana/Dirac distinction, and CP violating phases can be explored by measuring scattered photons ($\gamma$) along the excitation (and fiber) axis by varying Raman trigger (${\gamma }_0$) directions, in Er${}^{3+}$ de-excitation process from $|e⟩$ state to $|g⟩$ state; $|e⟩,|e⟩+{\gamma }_0\to |g⟩+\gamma +{\nu }_i{\bar{\nu }}_j$, ${\nu }_i,i=1,2,3$ being a mass-resolved neutrino state. Rates and required level of QED background rejection are calculated using measured data of the target system.

   hep-phcond-mat.mtrl-scihep-exphysics.atom-ph1 citation
10. 10*

    New Type of String Solutions with Long Range Forces

    Takashi Hiramatsu🇯🇵 · Masahiro Ibe🇯🇵 · Motoo Suzuki🇯🇵

    We explore the formation and the evolution of the string network in the Abelian Higgs model with two complex scalar fields. A special feature of the model is that it possesses a global $U(1)$ symmetry in addition to the $U(1)$ gauge symmetry. Both symmetries are spontaneously broken by the vacuum expectation values of the two complex scalar fields. As we will show the dynamics of the string network is quite rich compared with that in the ordinary Abelian Higgs model with a single complex scalar field. In particular, we find a new type of string solutions in addition to the conventional Abrikosov-Nielsen-Olesen (local) string solution. We call this the uncompensated string. An isolated uncompensated string has a logarithmic divergent string tension as in the case of the global strings, although it is accompanied by a non-trivial gauge field configuration. We also perform classical lattice simulations in the $2+1$ dimensional spacetime, which confirms the formation of the uncompensated strings at the phase transition. We also find that most of the uncompensated strings evolve into the local strings at later time when the gauge charge of the scalar field with a smaller vacuum expectation value is larger than that of the scalar field with a larger vacuum expectation value.

    hep-phastro-ph.COhep-thJHEP(2020)·13 citations
11. 11*

    Magnetic-dipole corrections to $R_K$ and $R_{K^{\ast }}$ in the Standard Model and Dark Photon scenarios

    Emidio Gabrielli🇮🇹 · Marco Palmiotto🇮🇹

    In this work we evaluate the long-distance QED contributions, induced by the magnetic-dipole corrections to the final charged leptons, on the $B$ meson decay widths $B\to (K,K^{\ast }){\ell }^{+}{\ell }^{-}$ and ratios $R_{K,K^{\ast }}=\Gamma (B\to (K,K^{\ast }){\mu }^{+}{\mu }^{-})/\Gamma (B\to (K,K^{\ast })e^{+}{e}^{-})$, as well as on $R_{K,K^{\ast }}^{\tau }$ (with $\mu$ replaced by the $\tau$ lepton). QED long-distance contributions induced by the Coulomb potential corrections (Fermi-Sommerfeld factors) were also included. Corresponding corrections to the inclusive decay widths of $B\to X_s{\ell }^{+}{\ell }^{-}$, with $\ell =e,\mu ,\tau$, are also analyzed for completeness. The magnetic-dipole corrections, which are manifestly Lepton Flavor Universality violating and gauge-invariant, are expected to be particularly enhanced in $R_{K^{\ast }}$ for the dilepton mass region close to the threshold. However, we find that the largest contribution of all these corrections to the $R_{K,K^{\ast }}$ observables do not exceed a few per mille effect, thus reinforcing the validity of previous estimates about the leading QED corrections to $R_{K,K^{\ast }}$. Finally, viable new physics contributions to $R_{K,K^{\ast }}$ induced by the exchange of a massless dark-photon via magnetic-dipole interactions, which provide the leading contribution to the corresponding $B\to (K,K^{\ast }){\ell }^{+}{\ell }^{-}$ amplitudes in this scenario, are analyzed in light of the present $R_{K,K^{\ast }}$ anomalies.

    hep-phJHEP(2020)·3 citations
12. 12*

    Neutron-antineutron oscillations in the deuteron studied with $NN$ and $\bar{N}N$ interactions based on chiral effective field theory

    Johann Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪

    Neutron-antineutron ($n-\bar{n}$) oscillations in the deuteron are considered. Specifically, the deuteron lifetime is calculated in terms of the free-space $n-\bar{n}$ oscillation time ${\tau }_{n-\bar{n}}$ based on $NN$ and $\bar{N}N$ interactions derived within chiral effective field theory (EFT). This results in $(2.6\pm 0.1)\times 10^{22}{\tau }_{n-\bar{n}}^2$ s, which is close to the value obtained by Dover and collaborators more than three decades ago, but disagrees with recent EFT calculations that were performed within the perturbative scheme proposed by Kaplan, Savage, and Wise. Possible reasons for the difference are discussed.

    hep-phnucl-thCPC(2020)·23 citations
13. 13*

    Prediction of an exotic state around 4240 MeV with $J^{PC}=1^{-+}$ as C-parity partner of Y(4260) in molecular picture

    Xiang-Kun Dong🇨🇳 · Yong-Hui Lin🇨🇳 · Bing-Song Zou🇨🇳

    The possibility of the Y(4260) being the molecular state of $D{\bar{D}}_1(2420)+c.c.$ is investigated in the one boson exchange model. It turns out that the potential of $J^{PC}=1^{--}$ state formed by $D{\bar{D}}_1(2420)+c.c.$ is attractive and strong enough to bind them together when the momentum cutoff $\Lambda \gtrsim 1.4$ GeV. To produce the Y(4260) with correct binding energy, we need $\Lambda \approx 2.1$ GeV. Besides, $D{\bar{D}}_1(2420)+c.c.$ can also form a state with exotic quantum numbers, $J^{PC}=1^{-+}$, and its potential similar with that of the $J^{PC}=1^{--}$ state. Therefore, an exotic state with mass around 4240 MeV (called ${\eta }_{c1}(4240)$) is predicted to exist. Our estimation of the mass of the $J^{PC}=1^{-+}$ state in charmonium region is in agreement with those predicted by the chiral quark model and the lattice QCD. The possible decay modes and their relative widths are estimated and the results suggest that this exotic state can be searched for in $\eta {\eta }_c$ and $\eta {\chi }_{c1}$ channels.

    hep-phPRD(2020)·36 citations
14. 14*

    Inspection of new physics in ${\mathrm{B}}_{\mathrm{s}}^0\to {\mathrm{K}}^{+}{\mathrm{K}}^{-}$ decay mode

    Manas K. Mohapatra🇮🇳

    We scrutinize the penguin dominated $B_s\to K^{+}{K}^{-}$ decay mode involving $b\to s$ quark level transition in family non-universal $Z^{\prime }$ and vector-like down quark model. There is discrepancy in the standard model branching ratio value of this mode with the experimental results reported by Belle, CDF and LHCb Collaborations. Additionally, the measured values of CP-violating asymmetries $C_{K^{+}{K}^{-}}$ and $S_{K^{+}{K}^{-}}$ deviate from the SM results. We constrain the new parameter space by using the existing experimental limits on leptonic $B_s\to \ell \ell$ ($\ell =e,\mu ,\tau$) processes. We then check the effects of new physics on the branching ratio and CP violating parameters of the $B_s\to K^{+}{K}^{-}$ process.

    hep-phPRD(2020)·3 citations
15. 15*

    Resolving the low mass puzzle of ${\Lambda }_c(2940{)}^{+}$

    Si-Qiang Luo🇨🇳 · Bing Chen🇨🇳 · Zhan-Wei Liu🇨🇳 · Xiang Liu🇨🇳

    For the long standing low mass puzzle of ${\Lambda }_c(2940{)}^{+}$, we propose an unquenched picture. Our calculation explicitly shows that the mass of the ${\Lambda }_c(2P,3/2^{-})$ state can be lowered down to be consistent with the experimental data of ${\Lambda }_c(2940{)}^{+}$ by introducing the $D^{\ast }N$ channel contribution. Additionally, we give a semi-quantitative analysis to illustrate why the ${\Lambda }_c(2940{)}^{+}$ state has a narrow width. It means that the low mass puzzle of ${\Lambda }_c(2940{)}^{+}$ can be solved. What is more important is that we predict a mass inversion relation for the $2P$ ${\Lambda }_c^{+}$ states, i.e., the ${\Lambda }_c(2P,1/2^{-})$ state is higher than the ${\Lambda }_c(2P,3/2^{-})$, which is totally different from the result of conventional quenched quark model. It provides a criterion to test such an unquenched scenario for ${\Lambda }_c(2940{)}^{+}$. We expect the future experimental progress from the LHCb and Belle II.

    hep-phhep-exEPJC(2020)·48 citations
16. 16*

    Inflection-Point Inflation with Axion Dark Matter in light of Trans-Planckian Censorship Conjecture

    Nobuchika Okada🇺🇸 · Digesh Raut🇺🇸 · Qaisar Shafi🇺🇸

    Motivated by the recently proposed Trans-Planckian Censorship Conjecture (TCC), we propose a gauged $B-L$ model of inflection-point inflation with axion dark matter. The Hubble scale during inflation ($H_{\inf }$) satisfies the TCC bound of $H_{\inf }\lesssim 1$ GeV, the axion dark matter scenario is free from the axion domain wall and isocurvature problems, and the axion decay constant can be larger than $10^{12}$ GeV. The seesaw mechanism is automatically incorporated in the model and the observed baryon asymmetry of the universe can be reproduced via resonant leptogenesis.

    hep-phastro-ph.COhep-thPLB(2021)·23 citations
17. 17*

    Blast-wave description of ${\rm Y}$ elliptic flow at energies available at the CERN Large Hadron Collider

    Klaus Reygers🇩🇪 · Alexander Schmah🇩🇪 · Anastasia Berdnikova🇷🇺 · Xu Sun🇺🇸

    A simultaneous blast-wave fit to particle yields and elliptic flow ($v_2$) measured as a function of transverse momentum in Pb-Pb collisions at LHC energies is presented. A compact formula for the calculation of $v_2(p_T)$ for an elliptic freeze-out surface is used which follows from the Cooper-Frye ansatz without further assumptions. Over the full available $p_T$ range, the ${\rm Y}$ elliptic flow data is described by the prediction based on the fit to lighter particles. This prediction shows that, due to the large ${\rm Y}$ mass, a sizable elliptic flow is only expected at transverse momenta above 10 GeV/$c$.

    hep-phnucl-exnucl-thPRC(2020)·23 citations
18. 18*

    Searching for Dark Photon Dark Matter with Cosmic Ray Antideuterons

    Lisa Randall🇺🇸 · Weishuang Linda Xu🇺🇸

    Low energy antideuteron detection presents a unique channel for indirect detection, targeting dark matter that annihilates into hadrons in a relatively background-free way. Since the idea was first proposed, many WIMP-type models have already been disfavored by direct detection experiments, and current constraints indicate that any thermal relic candidates likely annihilate through some hidden sector process. In this paper, we show that cosmic ray antideuteron detection experiments represent one of the best ways to search for hidden sector thermal relic dark matter, and in particular investigate a vector portal dark matter that annihilates via a massive dark photon. We find that the parameter space with thermal relic annihilation and $m_{\chi }>m_{A^{\prime }}\gtrsim 20\mathrm{GeV}$ is largely unconstrained, and near future antideuteron experiment \GAPS will be able to probe models in this space with $m_{\chi }\approx m_{A^{\prime }}$ up to masses of $O(100\mathrm{GeV})$. Specifically the dark matter models favored by the \textit{Fermi} Galactic center excess is expected to be detected or constrained at the $5(3)-\sigma$ level assuming a optimistic (conservative) propagation model.

    hep-phastro-ph.HEJHEP(2020)·7 citations
19. 19*

    Dark Matter meets Quantum Gravity

    Manuel Reichert🇩🇰 · Juri Smirnov🇺🇸

    We search for an extension of the Standard Model that contains a viable dark matter candidate and that can be embedded into a fundamental, asymptotically safe, quantum field theory with quantum gravity. Demanding asymptotic safety leads to boundary conditions for the non-gravitational couplings at the Planck scale. For a given dark matter model these translate into constraints on the mass of the dark matter candidate. We derive constraints on the dark matter mass and couplings in two minimal dark matter models: i) scalar dark matter coupled via the Higgs-portal in the $B$-$L$ model; ii) fermionic dark matter in a $U(1{)}_X$ extension of the Standard Model, coupled via the new gauge boson. For scalar dark matter we find 56 GeV $<M_{\text{DM}}<63$ GeV, and for fermionic dark matter $M_{\text{DM}}\le 50$ TeV. Within our framework, we identify three benchmark scenarios with distinct phenomenological consequences.

    hep-phgr-qchep-thPRD(2020)·86 citations
20. 20*

    Fat brane, dark matter and localized kinetic terms in six dimensions

    Ricardo G. Landim🇩🇪

    Extra dimensions (ED) have been used as attempts to explain several phenomena in particle physics over the years. In this paper we investigate the role of an abelian gauge field as mediator of the interaction between dark matter (DM) and Standard Model (SM) particles, in a model with two flat and transverse ED compactified on the chiral square. DM is confined in a thin brane, localized at the origin of the chiral square, while the SM is localized in a finite width brane, lying in the opposite corner of the square. A brane-localized kinetic term is present in the DM brane, while in the fat brane it is not allowed. In this model the kinetic mixing is not required because we assume that the SM particles couple to the mediator through their $B-L$ charges, while DM couples to it via a dark charge. Assuming a complex scalar field as DM candidate it is possible to obtain the observed DM relic abundance and avoid direct detection constraints for some parameter choices.

    hep-phastro-ph.COhep-thEPJC(2020)·4 citations
21. 21*

    Single inclusive jet photoproduction at very forward rapidities in $pp$ and $pPb$ collisions at the LHC

    V. P. Goncalves🇧🇷 · G. Sampaio dos Santos🇧🇷 · C. R. Sena🇧🇷

    The particle production at very forward rapidities is expected to be sensitive to the non-linear effects in the QCD dynamics at high energies. In this paper we present, for the first time, the predictions of the Color Dipole formalism for the single inclusive jet photoproduction in $pp$ and $pPb$ collisions considering the very forward rapidities probed by the CMS-CASTOR calorimeter, which will be characterized by a jet in the rapidity range of $5.2\le Y\le 6.6$, a rapidity gap in the rapidity range probed by the central CMS detector and one of the incident hadrons remaining intact in the final state. The transverse momentum distributions are estimated considering the more recent phenomenological models for the dipole-proton scattering amplitude, which are based on the Color Glass Condensate formalism and are able to describe the inclusive and exclusive $ep$ HERA data. Our results indicate that a future experimental analysis of this process is, in principle, feasible and useful to constrain the description of the QCD dynamics at high energies.

    hep-phhep-exEPJC(2020)·4 citations
22. 22*

    Loops in AdS: From the Spectral Representation to Position Space

    Dean Carmi🇨🇭

    We compute a family of scalar loop diagrams in $AdS$. We use the spectral representation to derive various bulk vertex/propagator identities, and these identities enable to reduce certain loop bubble diagrams to lower loop diagrams, and often to tree-level exchange or contact diagrams. An important example is the computation of the finite coupling 4-point function of the large-$N$ conformal $O(N)$ model on $Ad{S}_3$. Remarkably, the re-summation of bubble diagrams is equal to a tree-level contact diagram: the ${\bar{D}}_{1,1,\frac{3}{2},\frac{3}{2}}(z,\bar{z})$ function. Another example is a scalar with ${\varphi }^4$ or ${\varphi }^3$ coupling in $Ad{S}_3$: we compute various 4-point (and higher point) loop bubble diagrams with alternating integer and half-integer scaling dimensions in terms of a finite sum of contact diagrams and tree-level exchange diagrams. The 4-point function with external scaling dimensions differences obeying ${\Delta }_{12}=0$ and ${\Delta }_{34}=1$ enjoys significant simplicity which enables us to compute in quite generality. For integer or half-integer scaling dimensions, we show that the $M$-loop bubble diagram can be written in terms of Lerch transcendent functions of the cross-ratios $z$ and $\bar{z}$. Finally, we compute 2-point bulk bubble diagrams with endpoints in the bulk, and the result can be written in terms of Lerch transcendent functions of the AdS chordal distance. We show that the similarity of the latter two computations is not a coincidence, but arises from a vertex identity between the bulk 2-point function and the double-discontinuity of the boundary 4-point function.

    ↳ hep-thhep-phJHEP(2020)·61 citations
23. 23*

    Dark matter local density determination based on recent observations

    Pablo F. de Salas🇸🇪

    The local density of dark matter is an important quantity. On the one hand, its value is needed for dark matter direct detection searches. On the other hand, a precise and robust determination of the local dark matter density would help us learn about the shape of the dark matter halo of our Galaxy, which plays an important role in dark matter indirect detection searches, as well as in many studies in astrophysics and cosmology. There are different methods available to determine the local dark matter density. Among them, it is common to study either the vertical kinematics of a selected group of tracers or the rotation curve of the Milky Way. Recent estimates of the local dark matter density have used the precise observations conducted by the ESA/Gaia mission. However, in spite of the quality of the data released by Gaia's observations, different analyses of the local dark matter density produce dissimilar results. After a brief review of the most common methods to estimate the local density of dark matter, here we argue about different explanations for the discrepancies in the results of recent analyses. We finish by presenting new approaches that have been proposed in the literature and could help us improve our knowledge of this important quantity.

    ↳ astro-ph.GAhep-phJ.Phys.Conf.Ser.(2020)·20 citations
24. 24*

    Classifying and constraining local four photon and four graviton S-matrices

    Subham Dutta Chowdhury🇮🇳 · Abhijit Gadde🇮🇳 · Tushar Gopalka🇮🇳 · Indranil Halder🇮🇳 · Lavneet Janagal🇮🇳 · Shiraz Minwalla🇮🇳

    We study the space of all kinematically allowed four photon and four graviton S-matrices, polynomial in scattering momenta. We demonstrate that this space is the permutation invariant sector of a module over the ring of polynomials of the Mandelstam invariants $s$, $t$ and $u$. We construct these modules for every value of the spacetime dimension $D$, and so explicitly count and parameterize the most general four photon and four graviton S-matrix at any given derivative order. We also explicitly list the local Lagrangians that give rise to these S-matrices. We then conjecture that the Regge growth of S-matrices in all physically acceptable classical theories is bounded by $s^2$ at fixed $t$. A four parameter subset of the polynomial photon S-matrices constructed above satisfies this Regge criterion. For gravitons, on the other hand, no polynomial addition to the Einstein S-matrix obeys this bound for $D\le 6$. For $D\ge 7$ there is a single six derivative polynomial Lagrangian consistent with our conjectured Regge growth bound. Our conjecture thus implies that the Einstein four graviton S-matrix does not admit any physically acceptable polynomial modifications for $D\le 6$. A preliminary analysis also suggests that every finite sum of pole exchange contributions to four graviton scattering also such violates our conjectured Regge growth bound, at least when $D\le 6$, even when the exchanged particles have low spin.

    ↳ hep-thgr-qchep-phmath-ph+1JHEP(2020)·91 citations
25. 25*

    Resurgence of the Renormalization Group Equation

    Jahmall Bersini🇭🇷 · Alessio Maiezza🇭🇷 · Juan Carlos Vasquez🇺🇸

    We show how the renormalons emerge from the renormalization group equation with a priori no reference to any Feynman diagrams. The proof is rather given by recasting the renormalization group equation as a resurgent equation studied in the mathematical literature, which describes a function with an infinite number of singularities in the positive axis of the Borel plane. Consistency requires a one-to-one correspondence between the existence of such kind of equation and the actual (generalized) Borel resummation of the renormalons through a one-parameter transseries. Our finding suggests how non-perturbative contributions can affect the running couplings. We also discuss these concepts within the context of gauge theories, making use of the large number of flavor expansion.

    ↳ hep-thhep-phmath-phmath.MPAnnals Phys.(2020)·29 citations
26. 26*

    Identification of additional jets in the t-tbar b-bbar events using a deep neural network

    Jieun Choi🇰🇷 · Tae Jeong Kim🇰🇷 · Jongwon Lim🇰🇷 · Jiwon Park🇰🇷 · Yeonsu Ryou🇰🇷 · Juhee Song🇰🇷 · Soohyun Yun🇰🇷

    In the top quark pair production in association with the Higgs boson decaying to a b quark pair t-tbar H (b-bbar), the final state has an irreducible nonresonant background from the production of a top quark pair in association with a b quark pair t-tbar b-bbar. Therefore, understanding of the t-tbar b-bbar process precisely in particular differential cross-section as functions of the properties of the additional b jets not from the top quark decay is essential for improving the sensitivity of a search for the t-tbar H b-bbar process. The two additional b jets can be identified by using various approaches. In this paper, the performances are compared quantitatively in the lepton+jets decay channel in terms of the matching efficiency of assigning two additional b jets as a figure of merit. This study provides valuable information towards the precise measurement of differential cross-sections as a function of properties of the additional b jets in the t-tbar b-bbar events. We showed that a matching efficiency of around 40% could be achieved using a deep neural network method. In the events with at least 4 b jets, this performance is 8% better than that achieved using minimum Delta R(b,bbar) method. This is consistent with the boosted decision tree method within its statistical uncertainty.

    ↳ hep-exhep-phJ.Korean Phys.Soc.(2020)·3 citations
27. 27*

    Prospects for kaon physics at LHCb

    Francesco Dettori (for the LHCb Collaboration)🇮🇹

    Despite not being designed for it, the LHCb experiment has given world-leading contributions in kaon and hyperon physics. In this contribution I review the prospects for kaon physics at LHCb exploiting the already acquired data and the current and future Upgrade scenarios.

    ↳ hep-exhep-phJ.Phys.Conf.Ser.(2020)·1 citation
28. 28*

    Parity-Violating Inelastic Electron-Proton Scattering at Low $Q^2$ Above the Resonance Region

    QWeak Collaboration: D. Androic🇭🇷 · D.S. Armstrong🇺🇸 · A. Asaturyan🇦🇲 · K. Bartlett🇺🇸 · R.S. Beminiwattha🇺🇸 · J. Benesch🇺🇸 · F. Benmokhtar🇺🇸 · J. Birchall🇨🇦 · R.D. Carlini🇺🇸 · J.C. Cornejo🇺🇸 · M.M. Dalton🇺🇸 · C.A. Davis🇨🇦 and 64 other authors

    We report the measurement of the parity-violating asymmetry for the inelastic scattering of electrons from the proton, at $Q^2=0.082$ GeV${}^2$ and $W=2.23$ GeV, above the resonance region. The result $A_{\mathrm{Inel}}=-13.5\pm 2.0(\mathrm{stat})\pm 3.9(\mathrm{syst})$~ppm agrees with theoretical calculations, and helps to validate the modeling of the $\gamma Z$ interference structure functions $F_1^{\gamma Z}$ and $F_2^{\gamma Z}$ used in those calculations, which are also used for determination of the two-boson exchange box diagram (${\square }_{\gamma Z}$) contribution to parity-violating elastic scattering measurements. A positive parity-violating asymmetry for inclusive ${\pi }^{-}$ production was observed, as well as positive beam-normal single-spin asymmetry for scattered electrons and a negative beam-normal single-spin asymmetry for inclusive ${\pi }^{-}$ production.

    ↳ nucl-exhep-phPRC(2020)·8 citations
29. 29*

    Off-diagonal correlators of conserved charges from lattice QCD and how to relate them to experiment

    Rene Bellwied🇺🇸 · Szabolcs Borsanyi🇩🇪 · Zoltan Fodor🇩🇪 · Jana N. Guenther🇩🇪 · Jacquelyn Noronha-Hostler🇺🇸 · Paolo Parotto🇺🇸 · Attila Pasztor🇭🇺 · Claudia Ratti🇺🇸 · Jamie M. Stafford🇺🇸

    Like fluctuations, non-diagonal correlators of conserved charges provide a tool for the study of chemical freeze-out in heavy ion collisions. They can be calculated in thermal equilibrium using lattice simulations, and be connected to moments of event-by-event net-particle multiplicity distributions. We calculate them from continuum extrapolated lattice simulations at ${\mu }_B=0$, and present a finite-${\mu }_B$ extrapolation, comparing two different methods. In order to relate the grand canonical observables to the experimentally available net-particle fluctuations and correlations, we perform a Hadron Resonance Gas (HRG) model analysis, which allows us to completely break down the contributions from different hadrons. We then construct suitable hadronic proxies for fluctuations ratios, and study their behavior at finite chemical potentials. We also study the effect of introducing acceptance cuts, and argue that the small dependence of certain ratios on the latter allows for a direct comparison with lattice QCD results, provided that the same cuts are applied to all hadronic species. Finally, we perform a comparison for the constructed quantities for experimentally available measurements from the STAR Collaboration. Thus, we estimate the chemical freeze-out temperature to 165 MeV using a strangeness-related proxy. This is a rather high temperature for the use of the Hadron Resonance Gas, thus, further lattice studies are necessary to provide first principle results at intermediate ${\mu }_B$.

    ↳ hep-lathep-phPRD(2020)·82 citations
30. 30*

    Rapidity-dependent eccentricity scaling in relativistic heavy-ion collisions

    Rodrigo Franco🇧🇷 · Matthew Luzum🇧🇷

    There is a well-established relation between the spatial asymmetry in the initial stage of a heavy-ion collision and the final momentum anisotropy, which allows for a separation of effects from initial conditions vs. later evolution and has proved exceptionally powerful. However, until recently it has only been studied in two dimensions -- either through boost-invariant simulations or studying only quantities at mid-rapidity. We explore an extension to 3 dimensions, in order to determine whether a similar understanding can be obtained for the rapidity dependence of the collision system. In particular, we introduce rapidity-dependent eccentricities and investigate a trivial extension of the 2D eccentricity scaling of elliptic and triangular flow, as well as a way to systematically improve these initial-state estimators. We then explore the dependence of the resulting response coefficients on shear viscosity and initial total energy.

    ↳ nucl-thhep-phPLB(2020)·12 citations
31. 31*

    Searching for three-nucleon short-range correlations

    Misak M. Sargsian🇺🇸 · Donal B. Day🇺🇸 · Leonid L. Frankfurt🇮🇱 · Mark I. Strikman🇺🇸

    Three nucleon short range correlations~(SRCs) are one of the most elusive structures in nuclei. Their observation and the subsequent study of their internal makeup will have a significant impact on our understanding of the dynamics of super-dense nuclear matter which exists at the cores of neutron stars. We discuss the kinematic conditions and observables that are most favorable for probing 3N-SRCs in inclusive electro-nuclear processes and make a prediction for a quadratic dependence of the probabilities of finding a nucleon in 2N- and 3N- SRCs. We demonstrate that this prediction is consistent with the limited high energy experimental data available, suggesting that we have observed, for the first time, 3N-SRCs in electro-nuclear processes. Our analysis enables us to extract $a_3(A,Z)$, the probability of finding 3N-SRCs in nuclei relative to the A=3 system.

    ↳ nucl-thhep-phnucl-exPRC(2019)·16 citations
32. 32*

    Gauge Enhanced Quantum Criticality and Time Reversal Domain Wall: SU(2) Yang-Mills Dynamics with Topological Terms

    Juven Wang🇺🇸 · Yi-Zhuang You🇺🇸 · Yunqin Zheng🇺🇸

    We explore the low energy dynamics of the four siblings of Lorentz symmetry enriched SU(2) Yang-Mills theory with a theta term at $\theta =\pi$ in $(3+1)$d. Due to a mixed anomaly between time reversal symmetry and the center symmetry, the low energy dynamics must be nontrivial. We focus on two possible scenarios: 1) time reversal symmetry is spontaneously broken by the two confining vacua, and 2) the low energy theory is described by a U(1) Maxwell gauge theory (e.g. U(1) spin liquid in condensed matter) which is deconfined and gapless while preserving time reversal symmetry. In the first scenario, we first identify the global symmetry on the time reversal domain wall, where time reversal symmetry in the bulk induces a ${\mathbb{Z}}_2$ unitary symmetry on the domain wall. We discuss how the Lorentz symmetry and the unitary ${\mathbb{Z}}_2$ symmetry enrich the domain wall theory. In the second scenario, we relate the symmetry enrichments of the SU(2) Yang-Mills to that of the U(1) Maxwell gauge theory. This further opens up the possibility that SU(2) QCD with large and odd flavors of fermions could be a direct second order phase transition between two phases of U(1) gauge theories as well as between a U(1) gauge theory and a trivial vacuum (e.g. a trivial paramagnet), where the gauge group is enhanced to be non-Abelian at and only at the transition. We characterize these transitions, and name them as Gauge Enhanced Quantum Critical Points.

    ↳ cond-mat.str-elhep-phhep-thPRResearch(2020)·33 citations
33. 33*

    Beyond Standard Models and Grand Unifications: Anomalies, Topological Terms, and Dynamical Constraints via Cobordisms

    Zheyan Wan🇨🇳 · Juven Wang🇺🇸

    We classify and characterize all invertible anomalies and all allowed topological terms related to various Standard Models (SM), Grand Unified Theories (GUT), and Beyond Standard Model (BSM) physics. By all anomalies, we mean the inclusion of (1) perturbative/local anomalies captured by perturbative Feynman diagram loop calculations, classified by $\mathbb{Z}$ free classes, and (2) non-perturbative/global anomalies, classified by finite group ${\mathbb{Z}}_N$ torsion classes. Our work built from [arXiv:1812.11967] fuses the math tools of Adams spectral sequence, Thom-Madsen-Tillmann spectra, and Freed-Hopkins theorem. For example, we compute bordism groups ${\Omega }_d^G$ and their invertible topological field theory invariants, which characterize $d$d topological terms and $(d-1)$d anomalies, protected by the following symmetry group $G$: $Spin\times \frac{SU(3)\times SU(2)\times U(1)}{{\mathbb{Z}}_q}$ for SM with $q=1,2,3,6$; $\frac{Spin\times Spin(n)}{{\mathbb{Z}}_2^F}$ or $Spin\times Spin(n)$ for SO(10) or SO(18) GUT as $n=10,18$; $Spin\times SU(n)$ for Georgi-Glashow SU(5) GUT as $n=5$; $\frac{Spin\times \frac{SU(4)\times (SU(2)\times SU(2))}{{\mathbb{Z}}_{q^{\prime }}}}{{\mathbb{Z}}_2^F}$ for Pati-Salam GUT as $q^{\prime }=1,2$; and others. For SM with an extra discrete symmetry, we obtain new anomaly matching conditions of ${\mathbb{Z}}_{16}$, ${\mathbb{Z}}_4$, and ${\mathbb{Z}}_2$ classes in 4d beyond the familiar Witten anomaly. Our approach offers an alternative view of all anomaly matching conditions built from the lower-energy (B)SM or GUT, in contrast to high-energy Quantum Gravity or String Theory Landscape v.s. Swampland program, as bottom-up/top-down complements. Symmetries and anomalies provide constraints of kinematics, we further suggest constraints of quantum gauge dynamics, and new predictions of possible extended defects/excitations plus hidden BSM non-perturbative topological sectors.

    ↳ hep-thcond-mat.str-elhep-lathep-ph+1JHEP(2020)·86 citations
34. 34*

    $\lambda {\varphi }^4$ in dS

    Victor Gorbenko🇺🇸 · Leonardo Senatore🇺🇸

    We resolve the issue of infrared divergences present in theories of light scalar fields on de Sitter space.

    ↳ hep-thgr-qchep-ph183 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.