Thu·Mar 17, 2016Thursday·March 17, 2016

1. 01*

   Gluino Coannihilation and Observability of Gluinos at LHC RUN II

   Pran Nath🇺🇸 · Andrew B. Spisak🇺🇸

   The observability of a gluino at LHC RUN II is analyzed for the case where the gluino lies in the gluino-neutralino coannihilation region and the mass gap between the gluino and the neutralino is small. The analysis is carried out under the Higgs boson mass constraint and the constraint of dark matter relic density consistent with the WMAP and Planck experiment. It is shown that in this case a gluino with mass much smaller than the current lower limit of $\sim 1500$ GeV as given by LHC RUN II at 3.2 fb${}^{-1}$ of integrated luminosity would have escaped detection. The analysis is done using the signal regions used by the ATLAS Collaboration where an optimization of signal regions was carried out to determine the best regions for gluino discovery in the gluino-neutralino coannihilation region. It is shown that under the Higgs boson mass constraint and the relic density constraint, a gluino mass of $\sim 700$ GeV would require 14 fb${}^{-1}$ of integrated luminosity for discovery and a gluino of mass $\sim 1250$ GeV would require 3400 fb${}^{-1}$ of integrated luminosity for discovery at LHC RUN II. An analysis of dark matter for this case is also given. It is found that for the range of gluino masses considered, the neutralino mass lies within less than 100 GeV of the gluino mass. Thus a measurement of the gluino mass in the gluino-neutralino coannihilation region will provide a determination of the neutralino mass. In this region the neutralino is dominantly a gaugino and the spin-independent proton-neutralino cross section is small but much larger than the neutrino floor lying in the range $\sim (1-10)\times 10^{-47}$ cm${}^2$. Thus a significant part of the parameter space of the model will lie within the reach of the next generation LUX-ZEPLIN dark matter experiment.

   hep-phhep-exPRD(2016)·18 citations
2. 02*

   Dark Matter Inelastic Up-Scattering with the Interstellar Plasma: An Exciting New Source of X-Ray Lines, including at 3.5 keV

   Francesco D'Eramo🇺🇸 · Kevin Hambleton🇺🇸 · Stefano Profumo🇺🇸 · Tim Stefaniak🇺🇸

   We explore the phenomenology of a class of models where the dark matter particle can inelastically up-scatter to a heavier excited state via off-diagonal dipolar interactions with the interstellar plasma (gas or free electrons). The heavier particle then rapidly decays back to the dark matter particle plus a quasi-monochromatic photon. For the process to occur at appreciable rates, the mass splitting between the heavier state and the dark matter must be comparable to, or smaller than, the kinetic energy of particles in the plasma. As a result, the predicted photon line falls in the soft X-ray range, or, potentially, at arbitrarily lower energies. We explore experimental constraints from cosmology and particle physics, and present accurate calculations of the dark matter thermal relic density and of the flux of monochromatic X-rays from thermal plasma excitation. We find that the model provides a natural explanation for the observed 3.5 keV line from clusters of galaxies and from the Galactic center, and is consistent with null detections of the line from dwarf galaxies. The unique line shape, which will be resolved by future observations with the Hitomi (formerly Astro-H) satellite, and the predicted unique morphology and target-temperature dependence will enable easy discrimination of this class of models versus other scenarios for the generation of the 3.5 keV line or of any other unidentified line across the electromagnetic spectrum.

   hep-phastro-ph.COastro-ph.HEPRD(2016)·22 citations
3. 03*

   Implication of CMS data on photon PDFs

   Pazilet Obul🇨🇳 · Mamut Ababekri🇨🇳 · Sayipjamal Dulat🇨🇳 · Joshua Isaacson🇺🇸 · Carl Schmidt🇺🇸 · C.-P. Yuan🇺🇸

   As part of a recent analysis of exclusive two-photon production of W+ W- pairs at the LHC, the CMS experiment used di-lepton data to obtain an "effective" photon-photon luminosity. We show how the CMS analysis on their 8 TeV data, along with some assumptions about the likelihood for events in which the proton breaks up to pass the selection criteria, can be used to significantly constrain the photon parton distribution functions, such as those from the CTEQ, MRST, and NNPDF collaborations. We compare the data with predictions using these photon distributions, as well as the new LUXqed photon distribution. We study the impact of including these data on the NNPDF2.3QED, NNPDF3.0QED and CT14QEDinc fits. We find that these data place a usefil and complementary cross-check on the photon distribution, which is consistent with LUXqed prediction while suggesting that the NNPDF photon error band should be significantly reduced. Additionally, we propose a simple model for describing the two-photon production of W+ W- at the LHC. Using this model, we constrain the amount of inelastic photon that remains after the experimental cuts are applied.

   hep-phhep-exCPC(2018)·17 citations
4. 04*

   Suppressing structure formation at dwarf galaxy scales and below: late kinetic decoupling as a compelling alternative to warm dark matter

   Torsten Bringmann🇳🇴 · Haavard Tveit Ihle🇳🇴 · Joern Kersten🇳🇴 · Parampreet Walia🇳🇴

   Warm dark matter cosmologies have been widely studied as an alternative to the cold dark matter paradigm, the characteristic feature being a suppression of structure formation on small cosmological scales. A very similar situation occurs if standard cold dark matter particles are kept in local thermal equilibrium with a, possibly dark, relativistic species until the universe has cooled down to keV temperatures. We perform a systematic phenomenological study of this possibility, and classify all minimal models containing dark matter and an arbitrary radiation component that allow such a late kinetic decoupling. We recover explicit cases recently discussed in the literature and identify new classes of examples that are very interesting from a model-building point of view. In some of these models dark matter is inevitably self-interacting, which is remarkable in view of recent observational support for this possibility. Hence, dark matter models featuring late kinetic decoupling have the potential not only to alleviate the missing satellites problem but also to address other problems of the cosmological concordance model on small scales, in particular the cusp-core and too-big-too-fail problems, in some cases without invoking any additional input.

   hep-phastro-ph.COPRD(2016)·81 citations
5. 05*

   Implications of imaginary chemical potential for model building of QCD

   Kouji Kashiwa🇯🇵

   Properties of QCD at finite imaginary chemical potential are revisited to utilize for the model building of QCD in low energy regimes. For example, the electric holonomy which is closely related to the Polyakov-loop drastically affects thermodynamic quantities beside the Roberge-Weiss transition line. To incorporate several properties at finite imaginary chemical potential, it is important to introduce the holonomy effects to the coupling constant of effective models. This extension is possible by considering the entanglement vertex. We show justifications of the entanglement vertex based on the derivation of the effective four-fermi interaction in the Nambu--Jona-Lasinio model and present its general form with the local approximation. To discuss how to remove model ambiguities in the entanglement vertex, we calculate the chiral condensate with different ${\mathbb{Z}}_3$ sectors and the dual quark condensate.

   hep-phhep-lathep-th2 citations
6. 06*

   Evolution of Temperature Fluctuation in a Thermal bath and, its implications in Hadronic and Heavy-Ion Collisions

   Trambak Bhattacharya🇺🇸 · Prakhar Garg🇮🇳 · Raghunath Sahoo🇮🇳 · Prasant Samantray🇮🇳

   The evolution equation for inhomogeneous and anisotropic temperature fluctuations inside a medium is derived within the ambit of Boltzmann Transport Equation. Also, taking some existing realistic inputs we have analyzed the Fourier space variation of temperature fluctuation for the medium created after heavy-ion collisions. The effect of viscosity on the variation of fluctuations is investigated. Further, possible implications in hadronic and heavy-ion collisions are explored.

   hep-phhep-exnucl-exActa Phys.Polon.Supp.(2016)·0 citations
7. 07*

   The q-Statistics and QCD Thermodynamics at LHC

   Trambak Bhattacharyya🇮🇳 · Arvind Khuntia🇮🇳 · Pragati Sahoo🇮🇳 · Prakhar Garg🇮🇳 · Pooja Pareek🇮🇳 · Raghunath Sahoo🇮🇳 · Jean Cleymans🇿🇦

   We perform a Taylor series expansion of Tsallis distribution by assuming the Tsallis parameter $q$ close to 1. The $q$ value shows the deviation of a system from a thermalised Boltzmann distribution. By taking up to first order in $(q-1)$, we derive an analytical result for Tsallis distribution including radial flow. Further, in the present work, we also study the speed of sound ($c_s$) as a function of temperature using the non-extensive Tsallis statistics for different $q$ values and for different mass cut-offs.

   hep-phhep-exnucl-exActa Phys.Polon.Supp.(2016)·2 citations
8. 08*

   Indication of Differential Kinetic Freeze-out at RHIC and LHC Energies

   D. Thakur🇮🇳 · S. Tripathy🇮🇳 · P. Garg🇮🇳 · R. Sahoo and🇮🇳 · J. Cleymans🇿🇦

   The transverse momentum spectra at RHIC and LHC for A+A and p+p collisions are studied with Tsallis distributions in different approaches i.e. with and without radial flow. The information on the freeze-out surface in terms of freeze-out volume, temperature, chemical potential and radial flow velocities for different particle species are obtained. These parameters are found to show a systematic behavior with mass dependence. It is observed that the heavier particles freeze-out early as compared to lighter particles and freeze-out surfaces are different for different particles, which is a direct signature of mass dependent differential freeze-out. Further, we observe that the radial flow velocity decreases with increasing mass. This confirms the mass ordering behavior in collectivity observed in heavy-ion collisions. It is also observed that the systems created in peripheral heavy-ion collisions and in proton-proton collisions are of similar thermodynamic nature.

   hep-phhep-exnucl-exActa Phys.Polon.Supp.(2016)·10 citations
9. 09*

   Physics of leptoquarks in precision experiments and at particle colliders

   I. Doršner🇭🇷 · S. Fajfer🇸🇮 · A. Greljo🇨🇭 · J. F. Kamenik🇸🇮 · N. Košnik🇸🇮

   We present a comprehensive review of physics effects generated by leptoquarks (LQs), i.e., hypothetical particles that can turn quarks into leptons and vice versa, of either scalar or vector nature. These considerations include discussion of possible completions of the Standard Model that contain LQ fields. The main focus of the review is on those LQ scenarios that are not problematic with regard to proton stability. We accordingly concentrate on the phenomenology of light leptoquarks that is relevant for precision experiments and particle colliders. Important constraints on LQ interactions with matter are derived from precision low-energy observables such as electric dipole moments, (g-2) of charged leptons, atomic parity violation, neutral meson mixing, Kaon, B, and D meson decays, etc. We provide a general analysis of indirect constraints on the strength of LQ interactions with the quarks and leptons to make statements that are as model independent as possible. We address complementary constraints that originate from electroweak precision measurements, top, and Higgs physics. The Higgs physics analysis we present covers not only the most recent but also expected results from the Large Hadron Collider (LHC). We finally discuss direct LQ searches. Current experimental situation is summarized and self-consistency of assumptions that go into existing accelerator-based searches is discussed. A progress in making next-to-leading order predictions for both pair and single LQ productions at colliders is also outlined.

   hep-phhep-exPhys.Rept.(2016)·778 citations
10. 10*

    Peccei-Quinn symmetry for Dirac seesaw and leptogenesis

    Pei-Hong Gu🇨🇳

    We extend the DFSZ invisible axion model to simultaneously explain small Dirac neutrino masses and cosmic matter-antimatter asymmetry. After the Peccei-Quinn and electroweak symmetry breaking, the effective Yukawa couplings of the Dirac neutrinos to the standard model Higgs scalar can be highly suppressed by the ratio of the vacuum expectation value of an iso-triplet Higgs scalar over the masses of some heavy gauge-singlet fermions, iso-doublet Higgs scalars or iso-triplet fermions. The iso-triplet fields can carry a zero or nonzero hypercharge. Through the decays of the heavy gauge-singlet fermions, iso-doublet scalars or iso-triplet fermions, we can obtain a lepton asymmetry in the left-handed leptons and an opposite lepton asymmetry in the right-handed neutrinos. Since the right-handed neutrinos do not participate in the sphaleron processes, the left-handed lepton asymmetry can be partially converted to a baryon asymmetry.

    hep-phJCAP(2016)·40 citations
11. 11*

    Leptogenesis, radiative neutrino masses and inert Higgs triplet dark matter

    Wen-Bin Lu🇨🇳 · Pei-Hong Gu🇨🇳

    We extend the standard model by three types of inert fields including Majorana fermion singlets/triplets, real Higgs singlets/triplets and leptonic Higgs doublets. In the presence of a softly broken lepton number and an exactly conserved Z_2 discrete symmetry, these inert fields together can mediate a one-loop diagram for a Majorana neutrino mass generation. The heavier inert fields can decay to realize a successful leptogenesis while the lightest inert field can provide a stable dark matter candidate. As an example, we demonstrate the leptogenesis by the inert Higgs doublet decays. We also perform a systematic study on the inert Higgs triplet dark matter scenario where the interference between the gauge and Higgs portal interactions can significantly affect the dark matter properties.

    hep-phJCAP(2016)·45 citations
12. 12*

    Left-right asymmetry and 750 GeV diphoton excess

    D. T. Huong🇻🇳 · P. V. Dong🇻🇳

    We propose the left-right models based on SU(3)_C\otimes SU(M)_L \otimes SU(N)_R \otimes U(1)_X gauge symmetry for (M,N)=(3,3), (2,3), and (3,2) that address the 750 GeV diphoton excess recently reported by the LHC. The fermion contents are minimally introduced, and the generation number must match the fundamental color number to cancel anomalies and ensure QCD asymptotic freedom. The diphoton excess arises from the field that breaks the left-right symmetry spontaneously in the first model, while for the last models it emerges as an explicit violation of the left-right symmetry. The neutrino masses, flavor-changing neutral currents, and new boson searches are also discussed.

    hep-phPRD(2016)·37 citations
13. 13*

    Short Wavelength Oscillations with Right-Handed Neutrinos

    Emmanuel A. Paschos🇩🇪

    The standard model is extended with three right-handed, singlet neutrinos with general couplings permitted by the $SU(2{)}_L\times U(1)$ symmetry. The traditional oscillations are accounted for, as usually, by three left-handed neutrinos. The article investigates new structures that develop when the masses of the right-handed states are in the eV range. The new states interfere and oscillate with the standard light neutrinos. New structures appear when the detectors average over short wavelengths. I use these results to present and classify properties of the observed anomalies in the MiniBooNe, reactor and Gallium-detector experiments.

    hep-ph2 citations
14. 14*

    Cosmological tests of an axiverse-inspired quintessence field

    Razieh Emami🇨🇳 · Daniel Grin🇺🇸 · Josef Pradler🇦🇹 · Alvise Raccanelli🇺🇸 · Marc Kamionkowski🇺🇸

    Inspired by the string axiverse idea, it has been suggested that the recent transition from decelerated to accelerated cosmic expansion is driven by an axion-like quintessence field with a sub-Planckian decay constant. The scenario requires that the axion field be rather near the maximum of its potential, but is less finely tuned than other explanations of cosmic acceleration. The model is parametrized by an axion decay constant $f$, the axion mass $m$, and an initial misalignment angle $|{\theta }_i|$ which is close to $\pi$. In order to determine the $m$ and ${\theta }_i$ values consistent with observations, these parameters are mapped onto observables: the Hubble parameter $H(z)$ at and angular diameter distance $d_A(z)$ to redshift $z=0.57$, as well as the angular sound horizon of the cosmic microwave background (CMB). Measurements of the baryon acoustic oscillation (BAO) scale at $z\simeq 0.57$ by the BOSS survey and Planck measurements of CMB temperature anisotropies are then used to probe the $\left\{m,f,{\theta }_i\right\}$ parameter space. With current data, CMB constraints are the most powerful, allowing a fraction of only $\sim 0.2$ of the parameter-space volume. Measurements of the BAO scale made using the SPHEREx or SKA experiments could go further, observationally distinguishing all but $\sim 10^{-2}$ or $\sim 10^{-5}$ of the parameter-space volume (allowed by simple priors) from the $\Lambda$CDM model.

    ↳ astro-ph.COhep-phPRD(2016)·37 citations
15. 15*

    Event shape analysis in ultrarelativistic nuclear collisions

    Renata Kopecna🇨🇿 · Boris Tomasik🇸🇰

    We present a novel method for sorting events. So far, single variables like flow vector magnitude were used for sorting events. Our approach takes into account the whole azimuthal angle distribution rather than a single variable. This method allows us to determine the good measure of the event shape, providing a multiplicity-independent insight. We discuss the advantages and disadvantages of this approach, the possible usage in femtoscopy, and other more exclusive experimental studies.

    ↳ nucl-thhep-phnucl-exActa Phys.Polon.Supp.(2016)·0 citations
16. 16*

    On SYM theory and all order Bulk Singularity Structures of BPS Strings in type II theory

    Ehsan Hatefi🇦🇹

    The complete forms of the S-matrix elements of a transverse scalar field, two world volume gauge fields, and a Potential $C_{n-1}$ Ramond-Ramond (RR) form field are investigated. In order to find an infinite number of $t,s,(t+s+u)$-channel bulk singularity structures of this particular mixed open-closed amplitude, we employ all the conformal field theory techniques to $<V_{C^{-2}}{V}_{{\varphi }^0}{V}_{A^0}{V}_{A^0}>$, exploring all the entire correlation functions and all order ${\alpha }^{\prime }$ contact interactions to these supersymmetric Yang-Mills (SYM) couplings. Singularity and contact term comparisons with the other symmetric analysis, $<V_{C^{-1}}{V}_{{\varphi }^0}{V}_{A^{-1}}{V}_{A^0}>$ and $<V_{C^{-1}}{V}_{{\varphi }^{-1}}{V}_{A^0}{V}_{A^0}>$ are also carried out in detail. Various couplings from pull-Back of branes, Myers terms and several generalized Bianchi identities should be taken into account to be able to reconstruct all order ${\alpha }^{\prime }$ bulk singularities of type IIB (IIA) superstring theory. Finally, we make a comment on how to derive without any ambiguity all order ${\alpha }^{\prime }$ contact terms of this S-matrix which carry momentum of RR in transverse directions.

    ↳ hep-thgr-qchep-phNPB(2018)·3 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.