Mon·Jan 27, 2020Monday·January 27, 2020

1. 01*

   SO(10) unification with horizontal symmetry

   Avik Banerjee🇮🇳 · Gautam Bhattacharyya🇮🇳 · Palash B. Pal🇮🇳

   We extend the nonsupersymmetric SO(10) grand unification theories by adding a horizontal symmetry, which connects the three generations of fermions. Without committing to any specific symmetry group, we investigate the 1-loop renormalization group evolutions of the gauge couplings with one and two intermediate breaking scales. We find that depending on the SO(10) breaking chains, gauge coupling unification is compatible with only a handful of choices of representations of the Higgs bosons under the horizontal symmetry.

   hep-phPRD(2020)·3 citations
2. 02*

   Comparative analysis of $\omega p$, $\varphi p$, and $J/\psi p$ scattering lengths from A2, CLAS, and GlueX threshold measurements

   Igor Strakovsky (GWU)🇺🇸 · Lubomir Pentchev (JLab)🇺🇸 · Alexander Titov (JINR)🇷🇺

   The high accuracy $\varphi$-meson photoproduction data from the CLAS experiment in Hall~B of Jefferson Laboratory allow us to determine the near-threshold total cross section of the $\gamma p\to \varphi p$ reaction and use it for evaluating the $\varphi p$ scattering length ${\alpha }_{\varphi p}$. These data result in an absolute value of $|{\alpha }_{\varphi p}|=(0.063\pm 0.010)$~fm, which is smaller than the typical hadron size. A comparative analysis of ${\alpha }_{\varphi p}$ with the previously determined scattering lengths for $\omega p$ and $J/\psi p$ from the A2 and GlueX experiments is performed.

   hep-phhep-exnucl-exnucl-thPRC(2020)·56 citations
3. 03*

   Projected sensitivity to sub-GeV dark matter of next-generation semiconductor detectors

   Erik Andersson🇸🇪 · Alex Bökmark🇸🇪 · Riccardo Catena🇸🇪 · Timon Emken🇸🇪 · Henrik Klein Moberg🇸🇪 · Emil Åstrand🇸🇪

   We compute the projected sensitivity to dark matter (DM) particles in the sub-GeV mass range of future direct detection experiments using germanium and silicon semiconductor targets. We perform this calculation within the dark photon model for DM-electron interactions using the likelihood ratio as a test statistic, Monte Carlo simulations, and background models that we extract from recent experimental data. We present our results in terms of DM-electron scattering cross section values required to reject the background only hypothesis in favour of the background plus DM signal hypothesis with a statistical significance, $\mathcal{Z}$, corresponding to 3 or 5 standard deviations. We also test the stability of our conclusions under changes in the astrophysical parameters governing the local space and velocity distribution of DM in the Milky Way. In the best-case scenario, when a high-voltage germanium detector with an exposure of $50$ kg-year and a CCD silicon detector with an exposure of $1$ kg-year and a dark current rate of $1\times 10^{-7}$ counts/pixel/day have simultaneously reported a DM signal, we find that the smallest cross section value compatible with $\mathcal{Z}=3$ ($\mathcal{Z}=5$) is about $8\times 10^{-42}$ cm${}^2$ ($1\times 10^{-41}$ cm${}^2$) for contact interactions, and $4\times 10^{-41}$ cm${}^2$ ($7\times 10^{-41}$ cm${}^2$) for long-range interactions. Our sensitivity study extends and refine previous works in terms of background models, statistical methods, and treatment of the underlying astrophysical uncertainties.

   hep-phastro-ph.COJCAP(2020)·28 citations
4. 04*

   New Physics Signals of the Electroweak Chiral Lagrangian in Vector Boson Scattering at the LHC

   Claudia Garcia-Garcia🇪🇸

   The Standard Model of fundamental interactions, albeit an incredibly elegant and successful theory, lacks explanations for some experimental and theoretical open questions. Interestingly, many of these problems seem to be related to the electroweak symmetry breaking sector of the theory, whose dynamical generation is still unknown. Important questions such as what is the true nature of the Higgs boson, why is its mass so light and so close to that of the electroweak gauge bosons or whether the properties of this particle are the ones predicted in the Standard Model remain unanswered. The LHC is our tool to unveil these mysteries and vector boson scattering processes are the perfect window to access them, since they are considered as the most sensitive observables to new physics in the electroweak symmetry breaking sector. In this Thesis we employ the effective electroweak chiral Lagrangian with a light Higgs, which assumes a strongly interacting electroweak symmetry breaking sector, to perform a model independent analysis of the phenomenology of vector boson scattering processes at the LHC as well as to present quantitative predictions for the sensitivity to possible beyond the Standard Model physics scenarios.

   hep-ph2 citations
5. 05*

   Nuclear effects on jet substructure observables at the LHC

   Paul Caucal🇫🇷 · Edmond Iancu🇫🇷 · Gregory Soyez🇫🇷

   Using a pQCD picture for jet evolution in a dense QCD medium, in which medium-induced parton branchings are factorized from vacuum-like emissions, we study two jet substructure observables: the $z_g$ and the Soft Drop multiplicity distributions. We compute the respective nuclear modification factors using a Monte-Carlo implementation of the parton showers. Our results are in qualitative agreement with LHC data for Pb+Pb collisions. We identify the physical mechanisms explaining our results: incoherent jet energy loss, semi-hard medium-induced emissions and the bias introduced by the steeply falling jet spectrum.

   hep-phnucl-thNPA(2021)·1 citation
6. 06*

   Detecting a {\mu}{\tau}-philic Z' boson via photon initiated processes at the LHC

   Syuhei Iguro🇯🇵 · Kirtimaan A. Mohan🇺🇸 · C.-P. Yuan🇺🇸

   Discrepancy between the measured value and the Standard Model prediction of the muon anomalous magnetic moment is a possible hint for new physics. A $Z^{\prime }$ particle with $\mu \tau$ flavor violating couplings can give a large contribution to the muon anomalous magnetic moment due to the $\tau$ mass enhancement at the one-loop level, and is known to explain the above discrepancy. In this paper, we study the potential of the Large Hadron Collider (LHC) for detecting such a $Z^{\prime }$ boson via the $pp\to {\mu }^{-}{\mu }^{-}{\tau }^{+}{\tau }^{+}$ process. Earlier studies in the literature only considered the production channel with quark initial states ($pp\to q\bar{q}\to {\mu }^{-}{\mu }^{-}{\tau }^{+}{\tau }^{+}$). Here, we show that the photon initiated process, $pp\to \gamma \gamma \to {\mu }^{-}{\mu }^{-}{\tau }^{+}{\tau }^{+}$, is in fact the dominant production mode, for a heavy $Z^{\prime }$ boson of mass greater than a few hundred GeV. The potential of the high luminosity (HL) LHC is also considered.

   hep-phhep-exPRD(2020)·8 citations
7. 07*

   Heating neutron stars with GeV dark matter

   Wai-Yee Keung🇺🇸 · Danny Marfatia🇺🇸 · Po-Yan Tseng🇰🇷

   An old neutron star (NS) may capture halo dark matter (DM) and get heated up by the deposited kinetic energy, thus behaving like a thermal DM detector with sensitivity to a wide range of DM masses and a variety of DM-quark interactions. Near future infrared telescopes will measure NS temperatures down to a few thousand Kelvin and probe NS heating by DM capture. We focus on GeV-mass Dirac fermion DM (which is beyond the reach of current DM direct detection experiments) in scenarios in which the DM capture rate can saturate the geometric limit. For concreteness, we study (1) a model that invokes dark decays of the neutron to explain the neutron lifetime anomaly, and (2) a framework of DM coupled to quarks through a vector current portal. In the neutron dark decay model a NS can have a substantial DM population, so that the DM capture rate can reach the geometric limit through DM self-interactions even if the DM-neutron scattering cross section is tiny. We find NS heating to have greater sensitivity than multi-pion signatures in large underground detectors for the neutron dark decay model, and sub-GeV gamma-ray signatures for the quark vector portal model.

   hep-phastro-ph.HEastro-ph.SRhep-exJHEP(2020)·36 citations
8. 08*

   Impact of uncertainties in the halo velocity profile on direct detection of sub-GeV dark matter

   Andrzej Hryczuk🇵🇱 · Ekaterina Karukes🇵🇱 · Leszek Roszkowski🇵🇱 · Matthew Talia🇵🇱

   We use the state-of-the-art high-resolution cosmological simulations by IllustrisTNG to derive the velocity distribution and local density of dark matter in galaxies like our Milky Way and find a substantial spread in both quantities. Next we use our findings to examine the sensitivity to the dark matter velocity profile of underground searches using electron scattering in germanium and silicon targets. We find that sub-GeV dark matter search is strongly affected by these uncertainties, unlike nuclear recoil searches for heavier dark matter, especially in multiple electron-hole modes, for which the sensitivity to the scattering cross-section is also weaker. Therefore, by improving the sensitivity to lower ionization thresholds not only projected sensitivities will be boosted but also the dependence on the astrophysical uncertainties will become significantly reduced.

   hep-phJHEP(2020)·18 citations
9. 09*

   E_6 inspired composite Higgs model and baryon asymmetry generation

   R. Nevzorov🇷🇺 · A. W. Thomas🇦🇺

   The breakdown of SU(6) global symmetry down to its SU(5) subgroup near the scale f > 10 TeV in the strongly interacting sector within the E_6 inspired composite Higgs model (E6CHM) gives rise to a set of pseudo-Nambu-Goldstone bosons (pNGBs) that involves one Standard Model (SM) singlet scalar, a SM-like Higgs doublet and an SU(3)_C triplet of scalar fields, $T$. We argue that the baryon number violation in the E6CHM can induce the observed matter-antimatter asymmetry if CP is violated. The coloured triplet of scalar fields with mass in the few TeV range plays a key role in this process and may lead to a distinct new physics signal that can be detected at the LHC in the near future.

   hep-phhep-thPhys.Part.Nucl.(2020)·6 citations
10. 10*

    Dynamics of critical fluctuations: Theory -- phenomenology -- heavy-ion collisions

    M. Bluhm🇫🇷 · M. Nahrgang🇫🇷 · A. Kalweit🇨🇭 · M. Arslandok🇩🇪 · P. Braun-Munzinger🇩🇪 · S. Floerchinger🇩🇪 · E.S. Fraga🇧🇷 · M. Gazdzicki🇩🇪 · C. Hartnack🇫🇷 · C. Herold🇹🇭 · R. Holzmann🇩🇪 · Iu. Karpenko🇫🇷 and 18 other authors

    This report summarizes the presentations and discussions during the Rapid Reaction Task Force "Dynamics of critical fluctuations: Theory -- phenomenology -- heavy-ion collisions", which was organized by the ExtreMe Matter Institute EMMI and held at GSI, Darmstadt, Germany in April 2019. We address the current understanding of the dynamics of critical fluctuations in QCD and their measurement in heavy-ion collision experiments. In addition, we outline what might be learned from studying correlations in other physical systems, such as cold atomic gases.

    ↳ nucl-thhep-phnucl-exNPA(2020)·127 citations
11. 11*

    On the Injection of Relativistic Electrons in the Jet of 3C 279

    Wen Hu🇨🇳 · Dahai Yan🇨🇳 · Benzhong Dai🇨🇳 · Wei Zeng🇨🇳 · Qianglin Hu🇨🇳

    The acceleration of electrons in 3C 279 is investigated through analyzing the injected electron energy distribution (EED) in a time-dependent synchrotron self-Compton + external Compton emission model. In this model, it is assumed that relativistic electrons are continuously injected into the emission region, and the injected EED [$Q_e^{\prime }({\gamma }^{\prime })$] follows a single power-law form with low- and high-energy cutoffs ${\gamma }_{\min }^{\prime }$ and ${\gamma }_{\max }^{\prime }$, respectively, and the spectral index $n$, i.e, $Q_e^{\prime }({\gamma }^{\prime })\propto {\gamma }^{\prime -n}$. This model is applied to 14 quasi-simultaneous spectral energy distributions (SEDs) of 3C 279. The Markov Chain Monte Carlo fitting technique is performed to obtain the best-fitting parameters and the uncertainties on the parameters. The results show that the injected EED is well constrained in each state. The value of $n$ is in the range of 2.5 to 3.8, which is larger than that expected by the classic non-relativistic shock acceleration. However, the large value of $n$ can be explained by the relativistic oblique shock acceleration. The flaring activity seems to be related to an increased acceleration efficiency, reflected in an increased ${\gamma }_{\min }^{\prime }$ and electron injection power.

    ↳ astro-ph.HEhep-phMNRAS(2020)·6 citations
12. 12*

    Parity- and time-reversal-violating nuclear forces

    J. de Vries🇺🇸 · E. Epelbaum🇩🇪 · L. Girlanda🇮🇹 · A. Gnech🇮🇹 · E. Mereghetti🇺🇸 · M. Viviani🇮🇹

    Parity-violating and time-reversal conserving (PVTC) and parity-violating and time-reversal-violating (PVTV) forces in nuclei form only a tiny component of the total interaction between nucleons. The study of these tiny forces can nevertheless be of extreme interest because they allow to obtain information on fundamental symmetries using nuclear systems. The PVTC interaction derives from the weak interaction between the quarks inside nucleons and nuclei and the study of PVTC effects opens a window on the quark-quark weak interaction. The PVTV interaction is sensitive to more exotic interactions at the fundamental level, in particular to strong CP violation in the Standard Model Lagrangian, or even to exotic phenomena predicted in various beyond-the-Standard-Model scenarios. The presence of these interactions can be revealed either by studying various asymmetries in polarized scattering of nuclear systems, or by measuring the presence of non-vanishing permanent electric dipole moments of nucleons, nuclei and diamagnetic atoms and molecules. In this contribution, we review the derivation of the nuclear PVTC and PVTV interactions within various frameworks. We focus in particular on the application of chiral effective field theory, which allows for a more strict connection with the fundamental interactions at the quark level. We investigate PVTC and PVTV effects induced by these potential on several few-nucleon observables, such as the longitudinal asymmetry in proton-proton scattering and radiative neutron-proton capture, and the electric dipole momentsof the deuteron and the trinucleon system.

    ↳ nucl-thhep-phnucl-exFront.in Phys.(2020)·54 citations
13. 13*

    Standard Model Meets Gravity: Electroweak Symmetry Breaking and Inflation

    Mikhail Shaposhnikov🇨🇭 · Andrey Shkerin🇨🇭 · Sebastian Zell🇨🇭

    We propose a model for combining the Standard Model (SM) with gravity. It relies on a non-minimal coupling of the Higgs field to the Ricci scalar and on the Palatini formulation of gravity. Without introducing any new degrees of freedom in addition to those of the SM and the graviton, this scenario achieves two goals. First, it generates the electroweak symmetry breaking by a non-perturbative gravitational effect. In this way, it does not only address the hierarchy problem but opens up the possibility to calculate the Higgs mass. Second, the model incorporates inflation at energies below the onset of strong-coupling of the theory. Provided that corrections due to new physics above the scale of inflation are not unnaturally large, we can relate inflationary parameters to data from collider experiments.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2021)·51 citations
14. 14*

    Distinguishing freezing and thawing dark energy models through measurements of the fine-structure constant

    J. M. A. Vilas Boas🇵🇹 · D. M. N. Magano🇵🇹 · C. J. A. P. Martins🇵🇹 · A. Barbecho🇪🇸 · C. Serrano🇪🇸

    Mapping the behaviour of dark energy is a pressing task for observational cosmology. Phenomenological classification divides dynamical dark energy models into freezing and thawing, depending on whether the dark energy equation of state is approaching or moving away from $w=p/\rho =-1$. Moreover, in realistic dynamical dark energy models the dynamical degree of freedom is expected to couple to the electromagnetic sector, leading to variations of the fine-structure constant $\alpha$. We discuss the feasibility of distinguishing between the freezing and thawing classes of models with current and forthcoming observational facilities and using a parametrisation of the dark energy equation of state, which can have either behaviour, introduced by Mukhanov as fiducial paradigm. We illustrate how freezing and thawing models lead to different redshift dependencies of $\alpha$, and use a combination of current astrophysical observations and local experiments to constrain this class of models, improving the constraints on the key coupling parameter by more than a factor of two, despite considering a more extended parameter space than the one used in previous studies. We also briefly discuss the improvements expected from future facilities and comment on the practical limitations of this class of parametrisations. In particular, we show that sufficiently sensitive data can distinguish between freezing and thawing models, at least if one assumes that the relevant parameter space does not include phantom dark energy models.

    ↳ astro-ph.COgr-qchep-phAstron.Astrophys.(2020)·8 citations
15. 15*

    Signals of a Quantum Universe

    Daniel Green🇺🇸 · Rafael A. Porto🇩🇪

    Structure in the Universe is widely believed to have originated from quantum fluctuations during an early epoch of accelerated expansion. Yet, the patterns we observe today do not distinguish between quantum or classical primordial fluctuations; current cosmological data is consistent with either possibility. We argue here that a detection of primordial non-Gaussianity can resolve the present situation, and provide a litmus-test for the quantum origin of cosmic structure. Unlike in quantum mechanics, vacuum fluctuations cannot arise in classical theories and therefore long-range classical correlations must result from (real) particles in the initial state. Similarly to flat-space scattering processes, we show how basic principles require these particles to manifest themselves as poles in the $n$-point functions, in the so-called folded configurations. Following this observation, and assuming fluctuations are (i) correlated over large scales, and (ii) generated by local evolution during an inflationary phase, we demonstrate that: the absence of a pole in the folded limit of non-Gaussian correlators uniquely identifies the quantum vacuum as the initial state. In the same spirit as Bell's inequalities, we discuss how this can be circumvented if locality is abandoned. We also briefly discuss the implications for simulations of a non-Gaussian universe.

    ↳ hep-thastro-ph.COgr-qchep-phPRL(2020)·108 citations
16. 16*

    Curvature Perturbations From Stochastic Particle Production During Inflation

    Marcos A. G. Garcia🇪🇸 · Mustafa A. Amin🇺🇸 · Daniel Green🇺🇸

    We calculate the curvature power spectrum sourced by spectator fields that are excited repeatedly and non-adiabatically during inflation. In the absence of detailed information of the nature of spectator field interactions, we consider an ensemble of models with intervals between the repeated interactions and interaction strengths drawn from simple probabilistic distributions. We show that the curvature power spectra of each member of the ensemble shows rich structure with many features, and there is a large variability between different realizations of the same ensemble. Such features can be probed by the cosmic microwave background (CMB) and large scale structure observations. They can also have implications for primordial black hole formation and CMB spectral distortions. The geometric random walk behavior of the spectator field allows us to calculate the ensemble-averaged power spectrum of curvature perturbations semi-analytically. For sufficiently large stochastic sourcing, the ensemble-averaged power spectrum shows a scale dependence arising from the time spent by modes outside the horizon during the period of particle production, in spite of there being no preferred scale in the underlying model. We find that the magnitude of the ensemble-averaged power spectrum overestimates the typical power spectra in the ensemble because the ensemble distribution of the power spectra is highly non-Gaussian with fat tails.

    ↳ astro-ph.COhep-phhep-thJCAP(2020)·19 citations
17. 17*

    Exploring Primordial Black Holes from the Multiverse with Optical Telescopes

    Alexander Kusenko🇯🇵 · Misao Sasaki🇯🇵 · Sunao Sugiyama🇯🇵 · Masahiro Takada🇯🇵 · Volodymyr Takhistov🇺🇸 · Edoardo Vitagliano🇺🇸

    Primordial black holes (PBHs) are a viable candidate for dark matter if the PBH masses are in the currently unconstrained "sublunar" mass range. We revisit the possibility that PBHs were produced by nucleation of false vacuum bubbles during inflation. We show that this scenario can produce a population of PBHs that simultaneously accounts for all dark matter, explains the candidate event in Subaru Hyper Suprime-Cam (HSC) data, and contains both heavy black holes as observed by LIGO and very heavy seeds of supermassive black holes. We demonstrate with numerical studies that future observations of HSC, as well as other optical surveys, such as LSST, will be able to provide a definitive test for this generic PBH formation mechanism if it is the dominant source of dark matter.

    ↳ astro-ph.COgr-qchep-phhep-thPRL(2020)·146 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.