A
bstract
We discuss the upper limit,
k
max
, of the transverse-momentum integration performed in the
k
t
-factorization formula. Based on explicit calculations in the Yukawa theory and the study of ...seminal papers, we argue that
k
max
is equal to the factorization scale
μ
F
used to factorize the cross section into an off-shell hard coefficient and a universal factor. There is consequently a relation between
k
max
and the definition of unintegrated parton densities (UPDFs). The use of an inconsistent relation leads potentially to the overestimation of the cross section, which has been observed, e.g., in D-meson production
1
. One of our conclusions is that UPDFs related to collinear PDFs by an integration up to
μ
∼
Q
, where
Q
is the hard scale and
μ
the scale in the collinear PDFs, imply that
k
max
2
∼
Q
2
. Integrating the transverse-momentum significantly above may result in the overestimation of the cross section. On the opposite, for UPDFs related to the collinear ones by an integration of the transverse momentum up to infinity, any
k
max
2
> Q
2
is fine.
We show that a fluid dynamical scenario, already well tested against identified particle p(t) spectra, describes quantitatively the observed mass splitting of the elliptical flow coefficients v(2) ...for pions and protons. This provides a strong argument in favor of the existence of a fluid dynamical expansion in p-Pb collisions at 5.02 TeV.
Graviballs and dark matter Guiot, B.; Borquez, A.; Deur, A. ...
The journal of high energy physics,
11/2020, Letnik:
2020, Številka:
11
Journal Article
Recenzirano
Odprti dostop
A
bstract
We investigate the possible existence of graviballs, a system of bound gravitons, and show that two gravitons can be bound together by their gravitational interaction. This idea connects to ...black hole formation by a high-energy 2 →
N
scattering and to the gravitational geon studied by Brill and Hartle. Our calculations rely on the formalism and techniques of quantum field theory, specifically on low-energy quantum gravity. By solving numerically the relativistic equations of motion, we have access to the space-time dynamics of the (2-gravitons) graviball formation. We argue that the graviball is a viable dark matter candidate and we compute the associated gravitational lensing.
Vascular injury is an uncommon, but not rare complication of spine surgery. The consequence of vascular injury may be quite devastating, but its incidence can be reduced by understanding the ...mechanisms of injury. Properly managing vascular injury can reduce mortality and morbidity of patients. A review of the literature was conducted to provide an update on the etiology and management of vascular injury and complication in neurosurgical spine surgery. The vascular injuries were categorized according to each surgical procedure responsible for the injury, i.e., anterior screw fixation of the odontoid fracture, anterior cervical spine surgery, posterior C1-2 arthrodesis, posterior cervical spine surgery, anterolateral approach for thoracolumbar spine fracture, posterior thoracic spine surgery, scoliosis surgery, anterior lumbar interbody fusion (ALIF), lumbar disc arthroplasty, lumbar discectomy, and posterior lumbar spine surgery. The incidence, mechanisms of injury, and reparative measures were discussed for each surgical procedure. Detailed coverage was especially given to vascular injury associated with ALIF, which may have been underestimated. The accumulation of anatomical knowledge and advanced imaging studies has made complex spine surgery safer and more reliable. It is not clear, however, whether the incidence of vascular injury has been reduced significantly in all procedures of spine surgery. Emerging new techniques, such as microendoscopic discectomy and lumbar disc arthroplasty, seem to be promising, but we need to keep in mind their safety issues, including vascular injury and complication.
EPOS-LHC is the public EPOS version, heavily used by experimental groups in high energy and cosmic ray physics. It is based on an S-matrix approach, being the ideal framework for multiple scattering ...in small systems. However, factorization and binary scaling do not come for free, it is a very complex issue, and in the current model it is simply not properly done. Another topic concerns flow, which is only implemented as ‘‘parameterized,’’ with is quite a limited applications. There was substantial progress during the past few years, referred to as ‘‘EPOS4 project,’’ to develop a consistent formalism, which accommodates a multiple scattering S-matrix approach, factorization, and saturation, all of these topics being closely related to each other. In addition, secondary interactions are considered, most importantly a full hydrodynamic evolution. In this talk, we will report about the status of the EPOS4 project.
Iatrogenic vertebral artery injury Inamasu, J.; Guiot, B. H.
Acta neurologica Scandinavica,
December 2005, Letnik:
112, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Iatrogenic vertebral artery injury (VAI) results from various diagnostic and therapeutic procedures. The objective of this article is to provide an update on the mechanism of injury and management of ...this potentially devastating complication. A literature search was conducted using PubMed. The iatrogenic VAIs were categorized according to each diagnostic or therapeutic procedure responsible for the injury, i.e., central venous catheterization, cervical spine surgery, chiropractic manipulation, diagnostic cerebral angiography, percutaneous nerve block, and radiation therapy. The incidence, mechanisms of injury, and reparative procedures were discussed for each type of procedure. The type of VAI depends largely on the type of procedure. Laceration was the dominant type of acute injury in central venous catheterization and cervical spine surgery. Arteriovenous fistulae and pseudoaneurysms were the delayed complications. Arterial dissection was the dominant injury type in chiropractic manipulation and diagnostic cerebral angiography. Inadvertent arterial injection caused seizures or stroke in percutaneous nerve block. Radiation therapy was responsible for endothelial injury which in turn resulted in delayed stenosis and occlusion of the vertebral artery (VA). The proximal VA was the most vulnerable portion of the artery. Although iatrogenic VAIs are rare, they may actually be more prevalent than had previously been thought. Diagnosis of iatrogenic VAI may not always be easy because of its rarity and deep location, and a high level of suspicion is necessary for its early detection. A precise knowledge of the surgical anatomy of the VA is essential prior to each procedure to prevent its iatrogenic injury.
Hard probes and the event generator EPOS Guiot, B; Werner, K
Journal of physics. Conference series,
03/2015, Letnik:
589, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
After a short presentation of the event generator EPOS, we discuss the production of heavy quarks and prompt photons which has been recently implemented. Whereas we have satisfying results for the ...charm, work on photons is still in progress.
EPOS Werner, K.; Guiot, B.; Karpenko, Iu ...
EPJ Web of Conferences,
2019, Letnik:
208
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
We summarize the main features of the hadronic interaction model EPOS, which is used for cosmic ray air shower simulations but also for p-p, p-A, and A-A collisions to be compared with experimental ...data from LHC and RHIC.
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